DwAsm: check global bounds

Before, the space between FDEs was abstracted away, thought as dead
space that produced an error when queried. This is not the case, though:
empty FDEs indicate undefined DWARF

.gitignore

@@ -33,3 +33,4 @@
 
 dwarf-assembly
 __pycache__
+platform.info

README.md

@@ -1,10 +1,9 @@
 # Dwarf Assembly
 
-Some experiments around compiling the most used Dwarf informations (ELF debug
-data) directly into assembly.
+A compiler from DWARF unwinding data to native x86\_64 binaries.
 
-This project is a big work in progress, don't expect anything to be stable for
-now.
+This repository also contains various experiments, tools, benchmarking scripts,
+stats scripts, etc. to work on this compiler.
 
 ## Dependencies
 
@@ -17,7 +16,8 @@ As of now, this project relies on the following libraries:
     - [libsrk31cxx](https://github.com/stephenrkell/libsrk31cxx)
 
 These libraries are expected to be installed somewhere your compiler can find
-them.
+them. If you are using Archlinux, you can check
+[these `PKGBUILD`s](https://git.tobast.fr/m2-internship/pkgbuilds).
 
 ## Scripts and directories
 
@@ -26,4 +26,40 @@ them.
 * `./compare_sizes.py`: compare the sizes of the `.eh_frame` of a binary (and
   its dependencies) with the sizes of the `.text` of the generated ELFs.
 * `./extract_pc.py`: extracts a list of valid program counters of an ELF and
-  produce a file as read by `dwarf-assembly`
+  produce a file as read by `dwarf-assembly`, **deprecated**.
+
+* `benching`: all about benchmarking
+* `env`: environment variables manager to ease the use of various `eh_elf`s in
+  parallel, for experiments.
+* `shared`: code shared between various subprojects
+* `src`: the compiler code itself
+* `stack_walker`: a primitive stack walker using `eh_elf`s
+* `stack_walker_libunwind`: a primitive stack walker using vanilla `libunwind`
+* `stats`: a statistics gathering module
+* `tests`: some tests regarding `eh_elf`s, **deprecated**.
+
+## How to use
+
+To compile `eh_elf`s for a given ELF file, say `foo.bin`, it is recommended to
+use `generate_eh_elf.py`. Help can be obtained with `--help`. A standard
+command is
+
+```bash
+./generate_eh_elf.py --deps --enable-deref-arg --global-switch -o eh_elfs foo.bin
+```
+
+This will compile `foo.bin` and all the shared objects it relies on into
+`eh_elf`s, in the directory `./eh_elfs`, using a dereferencing argument (which
+is necessary for `perf-eh_elfs`).
+
+## Generate the intermediary C file
+
+If you're curious about the intermediary C file generated for a given ELF file
+`foo.bin`, you must call `dwarf-assembly` directly. A parameter `--help` can be
+passed; a standard command is
+
+```bash
+./dwarf-assembly --global-switch --enable-deref-arg foo.bin
+```
+
+**Beware**! This will generate the C code on the standard output.

benching/README.md

@@ -0,0 +1,92 @@
+# Benching `eh_elfs`
+
+## Benchmark setup
+
+Pick some name for your `eh_elfs` directory. We will call it `$EH_ELF_DIR`.
+
+### Generate the `eh_elfs`
+
+```bash
+../../generate_eh_elf.py --deps -o "$EH_ELF_DIR" \
+  --keep-holes -O2 --global-switch --enable-deref-arg "$BENCHED_BINARY"
+```
+
+### Record a `perf` session
+
+```bash
+perf record --call-graph dwarf,4096 "$BENCHED_BINARY" [args]
+```
+
+### Set up the environment
+
+```bash
+source ../../env/apply [vanilla | vanilla-nocache | *eh_elf] [dbg | *release]
+```
+
+The first value selects the version of libunwind you will be running, the
+second selects whether you want to run in debug or release mode (use release to
+get readings, debug to check for errors).
+
+You can reset your environment to its previous state by running `deactivate`.
+
+If you pick the `eh_elf` flavour, you will also have to
+
+```bash
+export LD_LIBRARY_PATH="$EH_ELF_DIR:$LD_LIBRARY_PATH"
+```
+
+## Extract results
+
+### Base readings
+
+**In release mode** (faster), run
+
+```bash
+perf report 2>&1 >/dev/null
+```
+
+with both `eh_elf` and `vanilla` shells. Compare average time.
+
+### Getting debug output
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null
+```
+
+### Total number of calls to `unw_step`
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null | grep -c "step:.* returning"
+```
+
+### Total number of vanilla errors
+
+With the `vanilla` context,
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null | grep -c "step:.* returning -"
+```
+
+### Total number of fallbacks to original DWARF
+
+With the `eh_elf` context,
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null | grep -c "step:.* falling back"
+```
+
+### Total number of fallbacks to original DWARF that actually used DWARF
+
+With the `eh_elf` context,
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null | grep -c "step:.* fallback with"
+```
+
+### Get succeeded fallback locations
+
+```bash
+UNW_DEBUG_LEVEL=5 perf report 2>&1 >/dev/null \
+  | grep "step: .* fallback with" -B 15 \
+  | grep "In memory map" | sort | uniq -c
+```

benching/csmith/.gitignore

@@ -0,0 +1 @@
+/tests

benching/csmith/csmith-bench.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+
+csmith "$@" | \
+    sed 's/#include "csmith.h"/#include <bench.h>\n#include <csmith.h>/g' |\
+    sed 's/return /bench_unwinding(); return /g'

benching/csmith/gen_call_graph.py

@@ -0,0 +1,124 @@
+#!/usr/bin/env python3
+
+""" Generates the call graph (in dot format) of a C code generated by CSmith.
+
+This does not parse C code, but performs only string lookups. In particular, it
+assumes functions are named `func_[0-9]+` or `main`, and that a function
+implementation is of the form (whitespaces meaningful)
+
+(static)? RETURN_TYPE func_[0-9]+(.*)
+{
+    ...
+}
+"""
+
+import sys
+import re
+
+
+def build_graph(prog):
+    func_declare_re = re.compile(r'(?:static )?\S.* (func_\d+|main) ?\(.*\)$')
+    func_call_re = re.compile(r'func_\d+')
+
+    graph = {}
+    cur_function = None
+
+    for line in prog:
+        func_declare_groups = func_declare_re.match(line)
+        if func_declare_groups:
+            func_name = func_declare_groups.group(1)
+            cur_function = func_name
+            graph[func_name] = []
+
+        elif line == '}':
+            cur_function = None
+
+        else:
+            if cur_function is None:
+                continue  # Not interresting outside of functions
+
+            last_find_pos = 0
+            call_match = func_call_re.search(line, pos=last_find_pos)
+
+            while call_match is not None:
+                graph[cur_function].append(call_match.group(0))
+                last_find_pos = call_match.end()
+                call_match = func_call_re.search(line, pos=last_find_pos)
+
+    reachable = set()
+    def mark_reachable(node):
+        nonlocal reachable, graph
+        if node in reachable:
+            return
+        reachable.add(node)
+
+        for child in graph[node]:
+            mark_reachable(child)
+    mark_reachable('main')
+
+    delete = []
+    for node in graph:
+        if node not in reachable:
+            delete.append(node)
+    for node in delete:
+        print('> Deleted: {}'.format(node), file=sys.stderr)
+        graph.pop(node)
+
+    return graph
+
+
+def dump_graph(graph):
+    print('digraph prog {')
+
+    for node in graph:
+        for call in graph[node]:
+            if call in graph:
+                print('\t{} -> {}'.format(node, call))
+            else:
+                print('Wtf is {} (called from {})?'.format(node, call),
+                      file=sys.stderr)
+    print('}')
+
+
+def dump_stats(graph, out_file):
+    entry_point = 'main'
+
+    depth_of = {}
+    def find_depth(node):
+        nonlocal depth_of
+
+        if node in depth_of:
+            return depth_of[node]
+
+        callees = graph[node]
+        if callees:
+            depth = max(map(find_depth, callees)) + 1
+        else:
+            depth = 1
+        depth_of[node] = depth
+        return depth
+
+    print("Call chain max depth: {}".format(find_depth(entry_point)),
+          file=out_file)
+
+
+def get_prog_lines():
+    def do_read(handle):
+        return handle.readlines()
+
+    if len(sys.argv) > 1:
+        with open(sys.argv[1], 'r') as handle:
+            return do_read(handle)
+    else:
+        return do_read(sys.stdin)
+
+
+def main():
+    prog = get_prog_lines()
+    graph = build_graph(prog)
+    dump_graph(graph)
+    dump_stats(graph, out_file=sys.stderr)
+
+
+if __name__ == '__main__':
+    main()

benching/gzip/.gitignore

@@ -0,0 +1,3 @@
+gzip
+gzip-1.10
+perf.data

benching/gzip/EVALUATION.md

@@ -0,0 +1,49 @@
+# gzip - evaluation
+
+Artifacts saved in `evaluation_artifacts`.
+
+## Performance
+
+Using the command line
+
+```bash
+for i in $(seq 1 100); do
+  perf report 2>&1 >/dev/null | tail -n 1 \
+    | python ../hackbench/to_report_fmt.py \
+    | sed 's/^.* & .* & \([0-9]*\) & .*$/\1/g'
+done
+```
+
+we save a sequence of 100 performance readings to some file.
+
+Samples:
+* `eh_elf`:  331134 unw/exec
+* `vanilla`: 331144 unw/exec
+
+Average time/unw:
+* `eh_elf`:    83 ns
+* `vanilla`: 1304 ns
+
+Standard deviation:
+* `eh_elf`:   2 ns
+* `vanilla`: 24 ns
+
+Average ratio: 15.7
+Ratio uncertainty: 0.8
+
+## Distibution of `unw_step` issues
+
+### `eh_elf` case
+
+* success:                              331134 (99.9%)
+* fallback to DWARF:                         2  (0.0%)
+* fallback to libunwind heuristics:          8  (0.0%)
+* fail to unwind:                          379  (0.1%)
+* total:                                331523
+
+### `vanilla` case
+
+* success:                              331136 (99.9%)
+* fallback to libunwind heuristics:          8  (0.0%)
+* fail to unwind:                          379  (0.1%)
+* total:                                331523

benching/hackbench/.gitignore

@@ -0,0 +1,5 @@
+/eh_elfs*
+/bench*
+/perf.data*
+/perfperf.data*
+/hackbench

benching/hackbench/EVALUATION.md

@@ -0,0 +1,48 @@
+# Hackbench - evaluation
+
+Artifacts saved in `evaluation_artifacts`.
+
+## Performance
+
+Using the command line
+
+```bash
+for i in $(seq 1 100); do
+  perf report 2>&1 >/dev/null | tail -n 1 \
+    | python to_report_fmt.py | sed 's/^.* & .* & \([0-9]*\) & .*$/\1/g'
+done
+```
+
+we save a sequence of 100 performance readings to some file.
+
+Samples:
+* `eh_elf`:  135251 unw/exec
+* `vanilla`: 138233 unw/exec
+
+Average time/unw:
+* `eh_elf`:   102 ns
+* `vanilla`: 2443 ns
+
+Standard deviation:
+* `eh_elf`:  2 ns
+* `vanilla`: 47 ns
+
+Average ratio: 24
+Ratio uncertainty: 1.0
+
+## Distibution of `unw_step` issues
+
+### `eh_elf` case
+
+* success:                              135251 (97.7%)
+* fallback to DWARF:                      1467  (1.0%)
+* fallback to libunwind heuristics:        329  (0.2%)
+* fail to unwind:                         1410  (1.0%)
+* total:                                138457
+
+### `vanilla` case
+
+* success:                              138201 (98.9%)
+* fallback to libunwind heuristics:         32  (0.0%)
+* fail to unwind:                         1411  (1.0%)
+* total:                                139644

benching/hackbench/Makefile

@@ -0,0 +1,4 @@
+all: hackbench
+
+hackbench: hackbench.c
+	gcc -Wall -Wextra -O2 -std=c11 -lpthread -o $@ $<

benching/hackbench/README.md

@@ -0,0 +1,44 @@
+# Running the benchmarks
+
+Pick some name for your `eh_elfs` directory. We will call it `$EH_ELF_DIR`.
+
+## Generate the `eh_elfs`
+
+```bash
+../../generate_eh_elf.py --deps -o "$EH_ELF_DIR" \
+  --keep-holes -O2 --global-switch --enable-deref-arg hackbench
+```
+
+## Record a `perf` session
+
+```bash
+perf record --call-graph dwarf,4096 ./hackbench 10 process 100
+```
+
+You can arbitrarily increase the first number up to ~100 and the second to get
+a longer session. This will most probably take all your computer's resources
+while it is running.
+
+## Set up the environment
+
+```bash
+source ../../env/apply [vanilla | vanilla-nocache | *eh_elf] [dbg | *release]
+```
+
+The first value selects the version of libunwind you will be running, the
+second selects whether you want to run in debug or release mode (use release to
+get readings, debug to check for errors).
+
+You can reset your environment to its previous state by running `deactivate`.
+
+If you pick the `eh_elf` flavour, you will also have to
+
+```bash
+export LD_LIBRARY_PATH="$EH_ELF_DIR:$LD_LIBRARY_PATH"
+```
+
+### Actually get readings
+
+```bash
+perf report 2>&1 >/dev/null
+```

benching/hackbench/hackbench.c

@@ -0,0 +1,399 @@
+
+/*
+ * This is the latest version of hackbench.c, that tests scheduler and
+ * unix-socket (or pipe) performance.
+ *
+ * Usage: hackbench [-pipe] <num groups> [process|thread] [loops]
+ *
+ * Build it with:
+ *   gcc -g -Wall -O2 -o hackbench hackbench.c -lpthread
+ */
+#if 0
+
+Date: Fri, 04 Jan 2008 14:06:26 +0800
+From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
+To: LKML <linux-kernel@vger.kernel.org>
+Subject: Improve hackbench
+Cc: Ingo Molnar <mingo@elte.hu>, Arjan van de Ven <arjan@infradead.org>
+
+hackbench tests the Linux scheduler. The original program is at 
+http://devresources.linux-foundation.org/craiger/hackbench/src/hackbench.c
+Based on this multi-process version, a nice person created a multi-thread
+version. Pls. see
+http://www.bullopensource.org/posix/pi-futex/hackbench_pth.c
+
+When I integrated them into my automation testing system, I found
+a couple of issues and did some improvements.
+
+1) Merge hackbench: I integrated hackbench_pth.c into hackbench and added a
+new parameter which can be used to choose process mode or thread mode. The
+default mode is process.
+
+2) It runs too fast and ends in a couple of seconds. Sometimes it's too hard to debug
+the issues. On my ia64 Montecito machines, the result looks weird when comparing
+process mode and thread mode.
+I want a stable result and hope the testing could run for a stable longer time, so I
+might use performance tools to debug issues.
+I added another new parameter,`loops`, which can be used to change variable loops,
+so more messages will be passed from writers to receivers. Parameter 'loops' is equal to
+100 by default.
+
+For example on my 8-core x86_64:
+[ymzhang@lkp-st01-x8664 hackbench]$ uname -a
+Linux lkp-st01-x8664 2.6.24-rc6 #1 SMP Fri Dec 21 08:32:31 CST 2007 x86_64 x86_64 x86_64 GNU/Linux
+[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench 
+Usage: hackbench [-pipe] <num groups> [process|thread] [loops]
+[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench 150 process 1000
+Time: 151.533
+[ymzhang@lkp-st01-x8664 hackbench]$ ./hackbench 150 thread 1000
+Time: 153.666
+
+
+With the same new parameters, I did captured the SLUB issue discussed on LKML recently.
+
+3) hackbench_pth.c will fail on ia64 machine because pthread_attr_setstacksize always
+fails if the stack size is less than 196*1024. I moved this statement within a __ia64__ check.
+
+
+This new program could be compiled with command line:
+#gcc -g -Wall  -o hackbench hackbench.c -lpthread
+
+
+Thank Ingo for his great comments!
+
+-yanmin
+
+---
+
+* Nathan Lynch <ntl@pobox.com> wrote:
+
+> Here's a fixlet for the hackbench program found at
+>
+> http://people.redhat.com/mingo/cfs-scheduler/tools/hackbench.c
+>
+> When redirecting hackbench output I am seeing multiple copies of the
+> "Running with %d*40 (== %d) tasks" line.  Need to flush the buffered
+> output before forking.
+
+#endif
+
+/* Test groups of 20 processes spraying to 20 receivers */
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sys/time.h>
+#include <sys/poll.h>
+#include <limits.h>
+
+#define DATASIZE 100
+static unsigned int loops = 100;
+/*
+ * 0 means thread mode and others mean process (default)
+ */
+static unsigned int process_mode = 1;
+
+static int use_pipes = 0;
+
+struct sender_context {
+	unsigned int num_fds;
+	int ready_out;
+	int wakefd;
+	int out_fds[0];
+};
+
+struct receiver_context {
+	unsigned int num_packets;
+	int in_fds[2];
+	int ready_out;
+	int wakefd;
+};
+
+
+static void barf(const char *msg)
+{
+	fprintf(stderr, "%s (error: %s)\n", msg, strerror(errno));
+	exit(1);
+}
+
+static void print_usage_exit()
+{
+	printf("Usage: hackbench [-pipe] <num groups> [process|thread] [loops]\n");
+	exit(1);
+}
+
+static void fdpair(int fds[2])
+{
+	if (use_pipes) {
+		if (pipe(fds) == 0)
+			return;
+	} else {
+		if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) == 0)
+			return;
+	}
+	barf("Creating fdpair");
+}
+
+/* Block until we're ready to go */
+static void ready(int ready_out, int wakefd)
+{
+	char dummy;
+	struct pollfd pollfd = { .fd = wakefd, .events = POLLIN };
+
+	/* Tell them we're ready. */
+	if (write(ready_out, &dummy, 1) != 1)
+		barf("CLIENT: ready write");
+
+	/* Wait for "GO" signal */
+	if (poll(&pollfd, 1, -1) != 1)
+		barf("poll");
+}
+
+/* Sender sprays loops messages down each file descriptor */
+static void *sender(struct sender_context *ctx)
+{
+	char data[DATASIZE];
+	unsigned int i, j;
+
+	ready(ctx->ready_out, ctx->wakefd);
+
+	/* Now pump to every receiver. */
+	for (i = 0; i < loops; i++) {
+		for (j = 0; j < ctx->num_fds; j++) {
+			int ret, done = 0;
+
+again:
+			ret = write(ctx->out_fds[j], data + done, sizeof(data)-done);
+			if (ret < 0)
+				barf("SENDER: write");
+			done += ret;
+			if (done < sizeof(data))
+				goto again;
+		}
+	}
+
+	return NULL;
+}
+
+
+/* One receiver per fd */
+static void *receiver(struct receiver_context* ctx)
+{
+	unsigned int i;
+
+	if (process_mode)
+		close(ctx->in_fds[1]);
+
+	/* Wait for start... */
+	ready(ctx->ready_out, ctx->wakefd);
+
+	/* Receive them all */
+	for (i = 0; i < ctx->num_packets; i++) {
+		char data[DATASIZE];
+		int ret, done = 0;
+
+again:
+		ret = read(ctx->in_fds[0], data + done, DATASIZE - done);
+		if (ret < 0)
+			barf("SERVER: read");
+		done += ret;
+		if (done < DATASIZE)
+			goto again;
+	}
+
+	return NULL;
+}
+
+pthread_t create_worker(void *ctx, void *(*func)(void *))
+{
+	pthread_attr_t attr;
+	pthread_t childid;
+	int err;
+
+	if (process_mode) {
+		/* process mode */
+		/* Fork the receiver. */
+		switch (fork()) {
+			case -1: barf("fork()");
+			case 0:
+				(*func) (ctx);
+				exit(0);
+		}
+
+		return (pthread_t) 0;
+	}
+
+	if (pthread_attr_init(&attr) != 0)
+		barf("pthread_attr_init:");
+
+#ifndef __ia64__
+	if (pthread_attr_setstacksize(&attr, PTHREAD_STACK_MIN) != 0)
+		barf("pthread_attr_setstacksize");
+#endif
+
+	if ((err=pthread_create(&childid, &attr, func, ctx)) != 0) {
+		fprintf(stderr, "pthread_create failed: %s (%d)\n", strerror(err), err);
+		exit(-1);
+	}
+	return (childid);
+}
+
+void reap_worker(pthread_t id)
+{
+	int status;
+
+	if (process_mode) {
+		/* process mode */
+		wait(&status);
+		if (!WIFEXITED(status))
+			exit(1);
+	} else {
+		void *status;
+
+		pthread_join(id, &status);
+	}
+}
+
+/* One group of senders and receivers */
+static unsigned int group(pthread_t *pth,
+		unsigned int num_fds,
+		int ready_out,
+		int wakefd)
+{
+	unsigned int i;
+	struct sender_context* snd_ctx = malloc (sizeof(struct sender_context)
+			+num_fds*sizeof(int));
+
+	for (i = 0; i < num_fds; i++) {
+		int fds[2];
+		struct receiver_context* ctx = malloc (sizeof(*ctx));
+
+		if (!ctx)
+			barf("malloc()");
+
+
+		/* Create the pipe between client and server */
+		fdpair(fds);
+
+		ctx->num_packets = num_fds*loops;
+		ctx->in_fds[0] = fds[0];
+		ctx->in_fds[1] = fds[1];
+		ctx->ready_out = ready_out;
+		ctx->wakefd = wakefd;
+
+		pth[i] = create_worker(ctx, (void *)(void *)receiver);
+
+		snd_ctx->out_fds[i] = fds[1];
+		if (process_mode)
+			close(fds[0]);
+	}
+
+	/* Now we have all the fds, fork the senders */
+	for (i = 0; i < num_fds; i++) {
+		snd_ctx->ready_out = ready_out;
+		snd_ctx->wakefd = wakefd;
+		snd_ctx->num_fds = num_fds;
+
+		pth[num_fds+i] = create_worker(snd_ctx, (void *)(void *)sender);
+	}
+
+	/* Close the fds we have left */
+	if (process_mode)
+		for (i = 0; i < num_fds; i++)
+			close(snd_ctx->out_fds[i]);
+
+	/* Return number of children to reap */
+	return num_fds * 2;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i, num_groups = 10, total_children;
+	struct timeval start, stop, diff;
+	unsigned int num_fds = 20;
+	int readyfds[2], wakefds[2];
+	char dummy;
+	pthread_t *pth_tab;
+
+	if (argv[1] && strcmp(argv[1], "-pipe") == 0) {
+		use_pipes = 1;
+		argc--;
+		argv++;
+	}
+
+	if (argc >= 2 && (num_groups = atoi(argv[1])) == 0)
+		print_usage_exit();
+
+	printf("Running with %d*40 (== %d) tasks.\n",
+		num_groups, num_groups*40);
+
+#ifdef MMAP
+    {
+        printf("Memory map:\n");
+        FILE* mmap = fopen("/proc/self/maps", "r");
+        char* line = (char*) malloc(512);
+        size_t line_size = 512;
+        while(getline(&line, &line_size, mmap) >= 0) {
+            printf(">> %s", line);
+        }
+        free(line);
+        puts("");
+        fclose(mmap);
+    }
+#endif // MMAP
+
+	fflush(NULL);
+
+	if (argc > 2) {
+		if ( !strcmp(argv[2], "process") )
+			process_mode = 1;
+		else if ( !strcmp(argv[2], "thread") )
+			process_mode = 0;
+		else
+			print_usage_exit();
+	}
+
+	if (argc > 3)
+		loops = atoi(argv[3]);
+
+	pth_tab = malloc(num_fds * 2 * num_groups * sizeof(pthread_t));
+
+	if (!pth_tab)
+		barf("main:malloc()");
+
+	fdpair(readyfds);
+	fdpair(wakefds);
+
+	total_children = 0;
+	for (i = 0; i < num_groups; i++)
+		total_children += group(pth_tab+total_children, num_fds, readyfds[1], wakefds[0]);
+
+	/* Wait for everyone to be ready */
+	for (i = 0; i < total_children; i++)
+		if (read(readyfds[0], &dummy, 1) != 1)
+			barf("Reading for readyfds");
+
+	gettimeofday(&start, NULL);
+
+	/* Kick them off */
+	if (write(wakefds[1], &dummy, 1) != 1)
+		barf("Writing to start them");
+
+	/* Reap them all */
+	for (i = 0; i < total_children; i++)
+		reap_worker(pth_tab[i]);
+
+	gettimeofday(&stop, NULL);
+
+	/* Print time... */
+	timersub(&stop, &start, &diff);
+	printf("Time: %lu.%03lu\n", diff.tv_sec, diff.tv_usec/1000);
+	exit(0);
+}
+
+

benching/hackbench/to_report_fmt.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+import re
+import sys
+
+line = input()
+regex = \
+    re.compile(r'Total unwind time: ([0-9]*) s ([0-9]*) ns, ([0-9]*) calls')
+
+match = regex.match(line.strip())
+if not match:
+    print('Badly formatted line', file=sys.stderr)
+    sys.exit(1)
+
+sec = int(match.group(1))
+ns = int(match.group(2))
+calls = int(match.group(3))
+
+time = sec * 10**9 + ns
+
+print("{} & {} & {} & ??".format(calls, time, time // calls))

benching/python3.7/test.py

@@ -0,0 +1,8 @@
+def slow_fibo(n):
+    if n <= 1:
+        return 1
+    return slow_fibo(n - 1) + slow_fibo(n - 2)
+
+
+if __name__ == "__main__":
+    slow_fibo(35)

benching/tools/common.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+if [ "$#" -lt 1 ] ; then
+    >&2 echo "Missing argument: directory"
+    exit 1
+fi
+
+BENCH_DIR="$(echo $1 | sed 's@/$@@g')"
+ENV_APPLY="$(readlink -f "$(dirname $0)/../../env/apply")"
+
+if ! [ -f "$ENV_APPLY" ] ; then
+    >&2 echo "Cannot find helper scripts. Abort."
+    exit 1
+fi
+
+function status_report {
+    echo -e "\e[33;1m[$BENCH_DIR]\e[0m $1"
+}

benching/tools/errors.sh

@@ -0,0 +1,101 @@
+#!/bin/bash
+
+source "$(dirname $0)/common.sh"
+
+TMP_FILE=$(mktemp)
+if [ -z "$EH_ELFS_NAME" ]; then
+    EH_ELFS_NAME="eh_elfs"
+fi
+
+function get_perf_output {
+    envtype=$1
+    source $ENV_APPLY "$envtype" "dbg"
+    LD_LIBRARY_PATH="$BENCH_DIR/$EH_ELFS_NAME:$LD_LIBRARY_PATH" \
+        UNW_DEBUG_LEVEL=15 \
+        perf report -i "$BENCH_DIR/perf.data" 2>$TMP_FILE >/dev/null
+    deactivate
+}
+
+function count_successes {
+    cat $TMP_FILE | tail -n 1 | sed 's/^.*, \([0-9]*\) calls.*$/\1/g'
+}
+
+function count_total_calls {
+    cat $TMP_FILE | grep -c "^  >.*step:.* returning"
+}
+
+function count_errors {
+    cat $TMP_FILE | grep -c "^  >.*step:.* returning -"
+}
+
+function count_eh_fallbacks {
+    cat $TMP_FILE | grep -c "step:.* falling back"
+}
+
+function count_vanilla_fallbacks {
+    cat $TMP_FILE | grep -c "step:.* frame-chain"
+}
+
+function count_fallbacks_to_dwarf {
+    cat $TMP_FILE | grep -c "step:.* fallback with"
+}
+
+function count_fallbacks_failed {
+    cat $TMP_FILE | grep -c "step:.* dwarf_step also failed"
+}
+
+function count_fail_after_fallback_to_dwarf {
+    cat $TMP_FILE \
+        | "$(dirname $0)/line_patterns.py" \
+            "fallback with" \
+            "step:.* unw_step called" \
+            ~"step:.* unw_step called" \
+            "step:.* returning -" \
+        | grep Complete -c
+}
+
+function report {
+    flavour="$1"
+
+    status_report "$flavour issues distribution"
+
+    successes=$(count_successes)
+    failures=$(count_errors)
+    total=$(count_total_calls)
+
+    if [ "$flavour" = "eh_elf" ]; then
+        fallbacks=$(count_eh_fallbacks)
+        fallbacks_to_dwarf=$(count_fallbacks_to_dwarf)
+        fallbacks_to_dwarf_failed_after=$(count_fail_after_fallback_to_dwarf)
+        fallbacks_failed=$(count_fallbacks_failed)
+        fallbacks_to_heuristics="$(( $fallbacks \
+            - $fallbacks_to_dwarf \
+            - $fallbacks_failed))"
+        echo -e "* success:\t\t\t\t$successes"
+        echo -e "* fallback to DWARF:\t\t\t$fallbacks_to_dwarf"
+        echo -e "* …of which failed at next step:\t$fallbacks_to_dwarf_failed_after"
+        echo -e "* fallback to libunwind heuristics:\t$fallbacks_to_heuristics"
+        computed_sum=$(( $successes + $fallbacks - $fallbacks_failed + $failures ))
+    else
+        fallbacks=$(count_vanilla_fallbacks)
+        successes=$(( $successes - $fallbacks ))
+        echo -e "* success:\t\t\t\t$successes"
+        echo -e "* fallback to libunwind heuristics:\t$fallbacks"
+        computed_sum=$(( $successes + $fallbacks + $failures ))
+    fi
+    echo -e "* fail to unwind:\t\t\t$failures"
+    echo -e "* total:\t\t\t\t$total"
+    if [ "$computed_sum" -ne "$total" ] ; then
+        echo "-- WARNING: missing cases (computed sum $computed_sum != $total) --"
+    fi
+}
+
+# eh_elf stats
+get_perf_output "eh_elf"
+report "eh_elf"
+
+# Vanilla stats
+get_perf_output "vanilla"
+report "vanilla"
+
+rm "$TMP_FILE"

benching/tools/errors_new.sh

@@ -0,0 +1,86 @@
+#!/bin/bash
+
+source "$(dirname $0)/common.sh"
+
+TMP_FILE=$(mktemp)
+
+function get_perf_output {
+    envtype=$1
+    source $ENV_APPLY "$envtype" "dbg"
+    LD_LIBRARY_PATH="$BENCH_DIR/eh_elfs:$LD_LIBRARY_PATH" \
+        UNW_DEBUG_LEVEL=15 \
+        perf report -i "$BENCH_DIR/perf.data" 2>$TMP_FILE >/dev/null
+    deactivate
+}
+
+function count_successes {
+    cat $TMP_FILE | tail -n 1 | sed 's/^.*, \([0-9]*\) calls.*$/\1/g'
+}
+
+function count_total_calls {
+    cat $TMP_FILE | grep -c "^  >.*step:.* returning"
+}
+
+function count_errors {
+    cat $TMP_FILE | grep -c "^  >.*step:.* returning -"
+}
+
+function count_eh_fallbacks {
+    cat $TMP_FILE | grep -c "step:.* falling back"
+}
+
+function count_vanilla_fallbacks {
+    cat $TMP_FILE | grep -c "step:.* frame-chain"
+}
+
+function count_fallbacks_to_dwarf {
+    cat $TMP_FILE | grep -c "step:.* fallback with"
+}
+
+function count_fallbacks_failed {
+    cat $TMP_FILE | grep -c "step:.* dwarf_step also failed"
+}
+
+function report {
+    flavour="$1"
+
+    status_report "$flavour issues distribution"
+
+    successes=$(count_successes)
+    failures=$(count_errors)
+    total=$(count_total_calls)
+
+    if [ "$flavour" = "eh_elf" ]; then
+        fallbacks=$(count_eh_fallbacks)
+        fallbacks_to_dwarf=$(count_fallbacks_to_dwarf)
+        fallbacks_failed=$(count_fallbacks_failed)
+        fallbacks_to_heuristics="$(( $fallbacks \
+            - $fallbacks_to_dwarf \
+            - $fallbacks_failed))"
+        echo -e "* success:\t\t\t\t$successes"
+        echo -e "* fallback to DWARF:\t\t\t$fallbacks_to_dwarf"
+        echo -e "* fallback to libunwind heuristics:\t$fallbacks_to_heuristics"
+        computed_sum=$(( $successes + $fallbacks - $fallbacks_failed + $failures ))
+    else
+        fallbacks=$(count_vanilla_fallbacks)
+        successes=$(( $successes - $fallbacks ))
+        echo -e "* success:\t\t\t\t$successes"
+        echo -e "* fallback to libunwind heuristics:\t$fallbacks"
+        computed_sum=$(( $successes + $fallbacks + $failures ))
+    fi
+    echo -e "* fail to unwind:\t\t\t$failures"
+    echo -e "* total:\t\t\t\t$total"
+    if [ "$computed_sum" -ne "$total" ] ; then
+        echo "-- WARNING: missing cases (computed sum $computed_sum != $total) --"
+    fi
+}
+
+# eh_elf stats
+get_perf_output "eh_elf"
+report "eh_elf"
+
+# Vanilla stats
+get_perf_output "vanilla"
+report "vanilla"
+
+rm "$TMP_FILE"

benching/tools/gen_evals.sh

@@ -0,0 +1,27 @@
+OUTPUT="$1"
+NB_ITER=10
+
+if [ "$#" -lt 1 ] ; then
+    >&2 echo "Missing argument: output directory."
+    exit 1
+fi
+
+if [ -z "$EH_ELFS" ]; then
+    >&2 echo "Missing environment: EH_ELFS. Aborting."
+    exit 1
+fi
+
+mkdir -p "$OUTPUT"
+
+for flavour in 'eh_elf' 'vanilla' 'vanilla-nocache'; do
+    >&2 echo "$flavour..."
+    source "$(dirname "$0")/../../env/apply" "$flavour" release
+    for iter in $(seq 1 $NB_ITER); do
+        >&2 echo -e "\t$iter..."
+        LD_LIBRARY_PATH="$EH_ELFS:$LD_LIBRARY_PATH" \
+            perf report 2>&1 >/dev/null | tail -n 1 \
+            | python "$(dirname $0)/to_report_fmt.py" \
+            | sed 's/^.* & .* & \([0-9]*\) & .*$/\1/g'
+    done > "$OUTPUT/${flavour}_times"
+    deactivate
+done

benching/tools/gen_perf_stats.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python3
+
+""" Generates performance statistics for the eh_elf vs vanilla libunwind unwinding,
+based on time series generated beforehand
+
+Intended to be run from `statistics.sh`
+"""
+
+from collections import namedtuple
+import numpy as np
+import sys
+import os
+
+
+Datapoint = namedtuple("Datapoint", ["nb_frames", "total_time", "avg_time"])
+
+
+def read_series(path):
+    with open(path, "r") as handle:
+        for line in handle:
+            nb_frames, total_time, avg_time = map(int, line.strip().split())
+            yield Datapoint(nb_frames, total_time, avg_time)
+
+
+FLAVOURS = ["eh_elf", "vanilla"]
+WITH_NOCACHE = False
+
+if "WITH_NOCACHE" in os.environ:
+    WITH_NOCACHE = True
+    FLAVOURS.append("vanilla-nocache")
+
+path_format = os.path.join(sys.argv[1], "{}_times")
+datapoints = {}
+avg_times = {}
+total_times = {}
+avgs_total = {}
+avgs = {}
+std_deviations = {}
+unwound_frames = {}
+
+for flv in FLAVOURS:
+    datapoints[flv] = list(read_series(path_format.format(flv)))
+    avg_times[flv] = list(map(lambda x: x.avg_time, datapoints[flv]))
+    total_times[flv] = list(map(lambda x: x.total_time, datapoints[flv]))
+    avgs[flv] = sum(avg_times[flv]) / len(avg_times[flv])
+    avgs_total[flv] = sum(total_times[flv]) / len(total_times[flv])
+    std_deviations[flv] = np.sqrt(np.var(avg_times[flv]))
+
+    cur_unwound_frames = list(map(lambda x: x.nb_frames, datapoints[flv]))
+    unwound_frames[flv] = cur_unwound_frames[0]
+    for run_id, unw_frames in enumerate(cur_unwound_frames[1:]):
+        if unw_frames != unwound_frames[flv]:
+            print(
+                "{}, run {}: unwound {} frames, reference unwound {}".format(
+                    flv, run_id + 1, unw_frames, unwound_frames[flv]
+                ),
+                file=sys.stderr,
+            )
+
+avg_ratio = avgs["vanilla"] / avgs["eh_elf"]
+ratio_uncertainty = (
+    1
+    / avgs["eh_elf"]
+    * (
+        std_deviations["vanilla"]
+        + avgs["vanilla"] / avgs["eh_elf"] * std_deviations["eh_elf"]
+    )
+)
+
+
+def format_flv(flv_dict, formatter, alterator=None):
+    out = ""
+    for flv in FLAVOURS:
+        val = flv_dict[flv]
+        altered = alterator(val) if alterator else val
+        out += "* {}: {}\n".format(flv, formatter.format(altered))
+    return out
+
+
+def get_ratios(avgs):
+    def avg_of(flavour):
+        return avgs[flavour] / avgs["eh_elf"]
+
+    if WITH_NOCACHE:
+        return "\n\tcached: {}\n\tuncached: {}".format(
+            avg_of("vanilla"), avg_of("vanilla-nocache")
+        )
+    else:
+        return avg_of("vanilla")
+
+
+print(
+    "Unwound frames:\n{}\n"
+    "Average whole unwinding time (one run):\n{}\n"
+    "Average time to unwind one frame:\n{}\n"
+    "Standard deviation:\n{}\n"
+    "Average ratio: {}\n"
+    "Ratio uncertainty: {}".format(
+        format_flv(unwound_frames, "{}"),
+        format_flv(avgs_total, "{} μs", alterator=lambda x: x // 1000),
+        format_flv(avgs, "{} ns"),
+        format_flv(std_deviations, "{}"),
+        get_ratios(avgs),
+        ratio_uncertainty,
+    )
+)

benching/tools/line_patterns.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+
+import sys
+import re
+
+
+class Match:
+    def __init__(self, re_str, negate=False):
+        self.re = re.compile(re_str)
+        self.negate = negate
+
+    def matches(self, line):
+        return self.re.search(line) is not None
+
+
+class Matcher:
+    def __init__(self, match_objs):
+        self.match_objs = match_objs
+        self.match_pos = 0
+        self.matches = 0
+
+        if not self.match_objs:
+            raise Exception("No match expressions provided")
+        if self.match_objs[-1].negate:
+            raise Exception("The last match object must be a positive expression")
+
+    def feed(self, line):
+        for cur_pos, exp in enumerate(self.match_objs[self.match_pos :]):
+            cur_pos = cur_pos + self.match_pos
+            if not exp.negate:  # Stops the for here, whether matching or not
+                if exp.matches(line):
+                    self.match_pos = cur_pos + 1
+                    print(
+                        "Passing positive {}, advance to {}".format(
+                            cur_pos, self.match_pos
+                        )
+                    )
+                    if self.match_pos >= len(self.match_objs):
+                        print("> Complete match, reset.")
+                        self.matches += 1
+                        self.match_pos = 0
+                return
+            else:
+                if exp.matches(line):
+                    print("Failing negative [{}] {}, reset".format(exp.negate, cur_pos))
+                    old_match_pos = self.match_pos
+                    self.match_pos = 0
+                    if old_match_pos != 0:
+                        print("> Refeed: ", end="")
+                        self.feed(line)
+                    return
+
+
+def get_args(args):
+    out_args = []
+    for arg in args:
+        negate = False
+        if arg[0] == "~":
+            negate = True
+            arg = arg[1:]
+        out_args.append(Match(arg, negate))
+    return out_args
+
+
+if __name__ == "__main__":
+    matcher = Matcher(get_args(sys.argv[1:]))
+    for line in sys.stdin:
+        matcher.feed(line)
+    print(matcher.matches)

benching/tools/statistics.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+
+source "$(dirname $0)/common.sh"
+
+TEMP_DIR="$(mktemp -d)"
+NB_RUNS=10
+
+function collect_perf_time_data {
+    envtype=$1
+    source $ENV_APPLY "$envtype" "release"
+    LD_LIBRARY_PATH="$BENCH_DIR/eh_elfs:$LD_LIBRARY_PATH" \
+        perf report -i "$BENCH_DIR/perf.data" 2>&1 >/dev/null \
+        | tail -n 1 \
+        | python "$(dirname $0)/to_report_fmt.py" \
+        | sed 's/^\([0-9]*\) & \([0-9]*\) & \([0-9]*\) & .*$/\1 \2 \3/g'
+    deactivate
+}
+
+function collect_perf_time_data_runs {
+    envtype=$1
+    outfile=$2
+    status_report "Collecting $envtype data over $NB_RUNS runs"
+    rm -f "$outfile"
+    for run in $(seq 1 $NB_RUNS); do
+        collect_perf_time_data "$envtype" >> "$outfile"
+    done
+}
+
+eh_elf_data="$TEMP_DIR/eh_elf_times"
+vanilla_data="$TEMP_DIR/vanilla_times"
+
+collect_perf_time_data_runs "eh_elf" "$eh_elf_data"
+collect_perf_time_data_runs "vanilla" "$vanilla_data"
+
+if [ -n "$WITH_NOCACHE" ]; then
+    vanilla_nocache_data="$TEMP_DIR/vanilla-nocache_times"
+    collect_perf_time_data_runs "vanilla-nocache" "$vanilla_nocache_data"
+fi
+
+status_report "benchmark statistics"
+python "$(dirname "$0")/gen_perf_stats.py" "$TEMP_DIR"
+
+rm -rf "$TEMP_DIR"

benching/tools/to_report_fmt.py

@@ -0,0 +1,21 @@
+#!/usr/bin/env python3
+
+import re
+import sys
+
+line = input()
+regex = \
+    re.compile(r'Total unwind time: ([0-9]*) s ([0-9]*) ns, ([0-9]*) calls')
+
+match = regex.match(line.strip())
+if not match:
+    print('Badly formatted line', file=sys.stderr)
+    sys.exit(1)
+
+sec = int(match.group(1))
+ns = int(match.group(2))
+calls = int(match.group(3))
+
+time = sec * 10**9 + ns
+
+print("{} & {} & {} & ??".format(calls, time, time // calls))

compare_sizes.py

@@ -9,7 +9,7 @@ import os
 import subprocess
 from collections import namedtuple
 
-from shared_python import elf_so_deps
+from shared_python import elf_so_deps, readlink_rec, DEFAULT_AUX_DIRS
 
 
 ''' An ELF object, including the path to the ELF itself, and the path to its
@@ -83,6 +83,11 @@ def objects_list(args):
 
     out = []
 
+    eh_elfs_dirs = (
+        args.eh_elfs
+        + ([] if args.no_dft_aux else DEFAULT_AUX_DIRS)
+    )
+
     if args.deps:
         objects = set(args.object)
         for obj in args.object:
@@ -92,8 +97,10 @@ def objects_list(args):
     else:
         objects = args.object
 
+    objects = list(map(readlink_rec, objects))
+
     for obj in objects:
-        out.append(ElfObject(obj, matching_eh_elf(args.eh_elfs, obj)))
+        out.append(ElfObject(obj, matching_eh_elf(eh_elfs_dirs, obj)))
 
     return out
 
@@ -113,20 +120,33 @@ def process_args():
     parser.add_argument('--eh-elfs', required=True, action='append',
                         help=("Indicate the directory in which eh_elfs are "
                               "located"))
+    parser.add_argument('-A', '--no-dft-aux', action='store_true',
+                        help=("Do not use the default eh_elf locations"))
     parser.add_argument('object', nargs='+',
                         help="The ELF object(s) to process")
     return parser.parse_args()
 
 
+def get_or_default(obj, field, default=None):
+    ''' Access a field of a subscriptable, returning a default if there is no
+    such field '''
+
+    if field not in obj:
+        return default
+    return obj[field]
+
+
 def main():
     args = process_args()
     objs = objects_list(args)
 
     col_names = [
         'Shared object',
+        'Orig prog size',
         'Orig eh_frame',
         'Gen eh_elf .text',
         '+ .rodata',
+        '% of prog size',
         'Growth',
     ]
 
@@ -143,20 +163,27 @@ def main():
                      '{:<' + col_len[1] + '}   '
                      '{:<' + col_len[2] + '}   '
                      '{:<' + col_len[3] + '}   '
-                     '{:<' + col_len[4] + '}')
+                     '{:<' + col_len[4] + '}   '
+                     '{:<' + col_len[5] + '}   '
+                     '{:<' + col_len[6] + '}')
     row_format = ('{:>' + col_len[0] + '}   '
                   '{:>' + col_len[1] + '}   '
                   '{:>' + col_len[2] + '}   '
                   '{:>' + col_len[3] + '}   '
-                  '{:>' + col_len[4] + '}')
+                  '{:>' + col_len[4] + '}   '
+                  '{:>' + col_len[5] + '}   '
+                  '{:>' + col_len[6] + '}')
     print(header_format.format(
         col_names[0],
         col_names[1],
         col_names[2],
         col_names[3],
         col_names[4],
+        col_names[5],
+        col_names[6],
     ))
 
+    total_program_size = 0
     total_eh_frame_size = 0
     total_eh_elf_text_size = 0
     total_eh_elf_size = 0
@@ -165,19 +192,32 @@ def main():
         elf_sections = get_elf_sections(obj.elf)
         eh_elf_sections = get_elf_sections(obj.eh_elf)
 
-        eh_frame_size = elf_sections['.eh_frame']['size']
-        eh_elf_text_size = eh_elf_sections['.text']['size']
-        eh_elf_size = eh_elf_text_size + eh_elf_sections['.rodata']['size']
+        text_size = get_or_default(
+            elf_sections, '.text', {'size': 0})['size']
+        rodata_size = get_or_default(
+            elf_sections, '.rodata', {'size': 0})['size']
+        eh_frame_size = get_or_default(
+            elf_sections, '.eh_frame', {'size': 0})['size']
+        eh_elf_text_size = get_or_default(
+            eh_elf_sections, '.text', {'size': 0})['size']
+        eh_elf_size = eh_elf_text_size + \
+            get_or_default(
+                eh_elf_sections, '.rodata', {'size': 0})['size']
 
+        program_size = text_size + rodata_size
+
+        total_program_size += program_size
         total_eh_frame_size += eh_frame_size
         total_eh_elf_text_size += eh_elf_text_size
         total_eh_elf_size += eh_elf_size
 
         print(row_format.format(
             displayed_name_filter(obj),
+            format_size(program_size),
             format_size(eh_frame_size),
             format_size(eh_elf_text_size),
             format_size(eh_elf_size),
+            '{:.2f}'.format(eh_elf_size / program_size * 100),
             '{:.2f}'.format(eh_elf_size / eh_frame_size)))
 
         # Checking for missed big sections
@@ -190,9 +230,11 @@ def main():
 
     print(row_format.format(
         'Total',
+        format_size(total_program_size),
         format_size(total_eh_frame_size),
         format_size(total_eh_elf_size),
         format_size(total_eh_elf_text_size),
+        '{:.2f}'.format(total_eh_elf_size / total_program_size * 100),
         '{:.2f}'.format(total_eh_elf_size / total_eh_frame_size)))
 
 

env/apply

@@ -0,0 +1,118 @@
+#!/bin/bash
+## Source this file.
+## Usage: apply [vanilla | vanilla-nocache | *eh_elf] [dbg | *release]
+
+# ==== INPUT ACQUISITION ====
+flavour="eh_elf"
+dbg="release"
+while [ "$#" -gt 0 ] ; do
+    case "$1" in
+        "vanilla" | "vanilla-nocache" | "eh_elf")
+            flavour="$1"
+            ;;
+        "dbg" | "release")
+            dbg="$1"
+            ;;
+        *)
+            >&2 echo "Unknown argument: $1"
+            exit 1
+            ;;
+    esac
+    shift
+done
+
+# ==== UNSET PREVIOUS ENVIRONMENT ====
+
+type -t deactivate
+[ -n "$(type -t deactivate)" ] && deactivate
+
+# ==== DEFINE DEACTIVATE ====
+
+function deactivate {
+    export CPATH="$CPATH_EHELFSAVE"
+    export LIBRARY_PATH="$LIBRARY_PATH_EHELFSAVE"
+    export LD_LIBRARY_PATH="$LD_LIBRARY_PATH_EHELFSAVE"
+    export PS1="$PS1_EHELFSAVE"
+    export PATH="$PATH_EHELFSAVE"
+
+    unset CPATH_EHELFSAVE
+    unset LIBRARY_PATH_EHELFSAVE
+    unset LD_LIBRARY_PATH_EHELFSAVE
+    unset PS1_EHELFSAVE
+    unset PATH_EHELFSAVE
+
+    unset deactivate
+}
+
+# ==== PREFIX ====
+export PERF_PREFIX="$HOME/local/perf-$flavour"
+
+LIBUNWIND_PREFIX="$HOME/local/libunwind"
+case "$flavour" in
+    "vanilla" | "vanilla-nocache" )
+        LIBUNWIND_PREFIX="${LIBUNWIND_PREFIX}-vanilla"
+        ;;
+    "eh_elf" )
+        LIBUNWIND_PREFIX="${LIBUNWIND_PREFIX}-eh_elf"
+        ;;
+    * )
+        >&2 echo "$flavour: unknown flavour"
+        exit 1
+        ;;
+esac
+case "$dbg" in
+    "dbg" )
+        LIBUNWIND_PREFIX="${LIBUNWIND_PREFIX}-dbg"
+        ;;
+    "release" )
+        LIBUNWIND_PREFIX="${LIBUNWIND_PREFIX}-release"
+        ;;
+    * )
+        >&2 echo "$dbg: unknown debug mode (release | dbg)"
+        exit 1
+        ;;
+esac
+
+export LIBUNWIND_PREFIX
+
+
+# ==== EXPORTING ENV VARS ====
+
+function colon_prepend {
+    if [ -z "$2" ]; then
+        echo "$1"
+    elif [ -z "$1" ] ; then
+        echo "$2"
+    else
+        echo "$1:$2"
+    fi
+}
+
+function ifpath {
+    if [ -e "$1" ] ; then
+        echo "$1"
+    fi
+}
+
+export CPATH_EHELFSAVE="$CPATH"
+export LIBRARY_PATH_EHELFSAVE="$LIBRARY_PATH"
+export LD_LIBRARY_PATH_EHELFSAVE="$LD_LIBRARY_PATH"
+export PATH_EHELFSAVE="$PATH"
+export PS1_EHELFSAVE="$PS1"
+
+export CPATH="$(colon_prepend \
+    "$LIBUNWIND_PREFIX/include/:$PERF_PREFIX/include" "$CPATH")"
+export LIBRARY_PATH="$(colon_prepend \
+    "$LIBUNWIND_PREFIX/lib/:$PERF_PREFIX/lib" "$LIBRARY_PATH")"
+export LD_LIBRARY_PATH="$(colon_prepend \
+    "$LIBUNWIND_PREFIX/lib/:$PERF_PREFIX/lib" "$LD_LIBRARY_PATH")"
+export PATH="$(colon_prepend \
+    "$(colon_prepend \
+        "$(ifpath "$LIBUNWIND_PREFIX/bin")" \
+        "$(ifpath "$PERF_PREFIX/bin")")" \
+    "$PATH")"
+
+export PS1="($flavour $dbg) $PS1"
+
+unset ifpath
+unset colon_prepend

generate_eh_elf.py

@@ -11,195 +11,427 @@ import sys
 import subprocess
 import tempfile
 import argparse
+from enum import Enum
 
-from shared_python import elf_so_deps, do_remote, is_newer
+from shared_python import (
+    elf_so_deps,
+    do_remote,
+    is_newer,
+    to_eh_elf_path,
+    find_eh_elf_dir,
+    DEFAULT_AUX_DIRS,
+)
 from extract_pc import generate_pc_list
 
 
 DWARF_ASSEMBLY_BIN = os.path.join(
-    os.path.dirname(os.path.abspath(sys.argv[0])),
-    'dwarf-assembly')
-C_BIN = (
-    'gcc' if 'C' not in os.environ
-    else os.environ['C'])
+    os.path.dirname(os.path.abspath(sys.argv[0])), "dwarf-assembly"
+)
+C_BIN = "gcc" if "C" not in os.environ else os.environ["C"]
 
 
-def gen_dw_asm_c(obj_path, out_path, dwarf_assembly_args):
-    ''' Generate the C code produced by dwarf-assembly from `obj_path`, saving
-    it as `out_path` '''
+class SwitchGenPolicy(Enum):
+    """ The various switch generation policies possible """
+
+    SWITCH_PER_FUNC = "--switch-per-func"
+    GLOBAL_SWITCH = "--global-switch"
+
+
+class Config:
+    """ Holds the run's settings """
+
+    default_aux = DEFAULT_AUX_DIRS
+
+    def __init__(
+        self,
+        output,
+        aux,
+        no_dft_aux,
+        objects,
+        sw_gen_policy=SwitchGenPolicy.GLOBAL_SWITCH,
+        force=False,
+        use_pc_list=False,
+        c_opt_level="3",
+        enable_deref_arg=False,
+        keep_holes=False,
+        cc_debug=False,
+        remote=None,
+    ):
+        self.output = "." if output is None else output
+        self.aux = aux + ([] if no_dft_aux else self.default_aux)
+        self.objects = objects
+        self.sw_gen_policy = sw_gen_policy
+        self.force = force
+        self.use_pc_list = use_pc_list
+        self.c_opt_level = c_opt_level
+        self.enable_deref_arg = enable_deref_arg
+        self.keep_holes = keep_holes
+        self.cc_debug = cc_debug
+        self.remote = remote
+
+    @staticmethod
+    def default_aux_str():
+        return ", ".join(Config.default_aux)
+
+    def dwarf_assembly_args(self):
+        """ Arguments to `dwarf_assembly` """
+        out = []
+        out.append(self.sw_gen_policy.value)
+        if self.enable_deref_arg:
+            out.append("--enable-deref-arg")
+        if self.keep_holes:
+            out.append("--keep-holes")
+        return out
+
+    def cc_opts(self):
+        """ Options to pass to the C compiler """
+        out = ["-fPIC"]
+        if self.cc_debug:
+            out.append("-g")
+        out.append(self.opt_level())
+        return out
+
+    def opt_level(self):
+        """ The optimization level to pass to gcc """
+        return "-O{}".format(self.c_opt_level)
+
+    def aux_dirs(self):
+        """ Get the list of auxiliary directories """
+        return self.aux
+
+
+def gen_dw_asm_c(obj_path, out_path, config, pc_list_path=None):
+    """ Generate the C code produced by dwarf-assembly from `obj_path`, saving
+    it as `out_path` """
+
+    dw_assembly_args = config.dwarf_assembly_args()
+    if pc_list_path is not None:
+        dw_assembly_args += ["--pc-list", pc_list_path]
 
     try:
-        with open(out_path, 'w') as out_handle:
+        with open(out_path, "w") as out_handle:
             # TODO enhance error handling
-            dw_asm_output = subprocess.check_output(
-                [DWARF_ASSEMBLY_BIN, obj_path] + dwarf_assembly_args) \
-                .decode('utf-8')
+            command_args = [DWARF_ASSEMBLY_BIN, obj_path] + dw_assembly_args
+            dw_asm_output = subprocess.check_output(command_args).decode("utf-8")
             out_handle.write(dw_asm_output)
     except subprocess.CalledProcessError as exn:
         raise Exception(
-            ("Cannot generate C code from object file {} using {}: process "
-             "terminated with exit code {}.").format(
-                 obj_path,
-                 DWARF_ASSEMBLY_BIN,
-                 exn.returncode))
+            (
+                "Cannot generate C code from object file {} using {}: process "
+                "terminated with exit code {}."
+            ).format(obj_path, DWARF_ASSEMBLY_BIN, exn.returncode)
+        )
 
 
-def gen_eh_elf(obj_path, args, dwarf_assembly_args=None):
-    ''' Generate the eh_elf corresponding to `obj_path`, saving it as
+def resolve_symlink_chain(objpath):
+    """ Resolves a symlink chain. This returns a pair `(new_obj, chain)`,
+    `new_obj` being the canonical path for `objpath`, and `chain` being a list
+    representing the path followed, eg. `[(objpath, a), (a, b), (b, new_obj)]`.
+    The goal of this function is to allow reproducing symlink architectures at
+    the eh_elf level. """
+
+    chain = []
+    out_path = objpath
+
+    while os.path.islink(out_path):
+        new_path = os.readlink(out_path)
+        if not os.path.isabs(new_path):
+            new_path = os.path.join(os.path.dirname(out_path), new_path)
+        chain.append((out_path, new_path))
+        out_path = new_path
+
+    return (out_path, chain)
+
+
+def find_out_dir(obj_path, config):
+    """ Find the directory in which the eh_elf corresponding to `obj_path` will
+    be outputted, among the output directory and the aux directories """
+
+    return find_eh_elf_dir(obj_path, config.aux_dirs(), config.output)
+
+
+def gen_eh_elf(obj_path, config):
+    """ Generate the eh_elf corresponding to `obj_path`, saving it as
     `out_dir/$(basename obj_path).eh_elf.so` (or in the current working
-    directory if out_dir is None) '''
+    directory if out_dir is None) """
 
-    if args.output is None:
-        out_dir = '.'
-    else:
-        out_dir = args.output
-
-    if dwarf_assembly_args is None:
-        dwarf_assembly_args = []
+    out_dir = find_out_dir(obj_path, config)
+    obj_path, link_chain = resolve_symlink_chain(obj_path)
 
     print("> {}...".format(os.path.basename(obj_path)))
 
-    out_base_name = os.path.basename(obj_path) + '.eh_elf'
-    out_so_path = os.path.join(out_dir, (out_base_name + '.so'))
-    pc_list_dir = os.path.join(out_dir, 'pc_list')
+    link_chain = map(
+        lambda elt: (
+            to_eh_elf_path(elt[0], out_dir),
+            os.path.basename(to_eh_elf_path(elt[1], out_dir)),
+        ),
+        link_chain,
+    )
 
-    if is_newer(out_so_path, obj_path) and not args.force:
+    out_base_name = to_eh_elf_path(obj_path, out_dir, base=True)
+    out_so_path = to_eh_elf_path(obj_path, out_dir, base=False)
+    pc_list_dir = os.path.join(out_dir, "pc_list")
+
+    if is_newer(out_so_path, obj_path) and not config.force:
         return  # The object is recent enough, no need to recreate it
 
+    if os.path.exists(out_dir) and not os.path.isdir(out_dir):
+        raise Exception("The output path {} is not a directory.".format(out_dir))
+    if not os.path.exists(out_dir):
+        os.makedirs(out_dir, exist_ok=True)
+
     with tempfile.TemporaryDirectory() as compile_dir:
         # Generate PC list
-        if args.use_pc_list:
-            pc_list_path = \
-                os.path.join(pc_list_dir, out_base_name + '.pc_list')
+        pc_list_path = None
+        if config.use_pc_list:
+            pc_list_path = os.path.join(pc_list_dir, out_base_name + ".pc_list")
             os.makedirs(pc_list_dir, exist_ok=True)
-            print('\tGenerating PC list…')
+            print("\tGenerating PC list…")
             generate_pc_list(obj_path, pc_list_path)
-            dwarf_assembly_args += ['--pc-list', pc_list_path]
 
         # Generate the C source file
         print("\tGenerating C…")
-        c_path = os.path.join(compile_dir, (out_base_name + '.c'))
-        gen_dw_asm_c(obj_path, c_path, dwarf_assembly_args)
+        c_path = os.path.join(compile_dir, (out_base_name + ".c"))
+        gen_dw_asm_c(obj_path, c_path, config, pc_list_path)
 
         # Compile it into a .o
         print("\tCompiling into .o…")
-        o_path = os.path.join(compile_dir, (out_base_name + '.o'))
-        opt_level = args.c_opt_level
-        if opt_level is None:
-            opt_level = '-O3'
-        if args.remote:
+        o_path = os.path.join(compile_dir, (out_base_name + ".o"))
+        if config.remote:
             remote_out = do_remote(
-                args.remote,
-                [C_BIN,
-                 '-o', out_base_name + '.o',
-                 '-c', out_base_name + '.c',
-                 opt_level, '-fPIC'],
+                config.remote,
+                [C_BIN, "-o", out_base_name + ".o", "-c", out_base_name + ".c"]
+                + config.cc_opts(),
                 send_files=[c_path],
-                retr_files=[(out_base_name + '.o', o_path)])
+                retr_files=[(out_base_name + ".o", o_path)],
+            )
             call_rc = 1 if remote_out is None else 0
         else:
             call_rc = subprocess.call(
-                [C_BIN, '-o', o_path, '-c', c_path, opt_level, '-fPIC'])
+                [C_BIN, "-o", o_path, "-c", c_path, config.opt_level(), "-fPIC"]
+            )
         if call_rc != 0:
             raise Exception("Failed to compile to a .o file")
 
         # Compile it into a .so
         print("\tCompiling into .so…")
-        call_rc = subprocess.call(
-            [C_BIN, '-o', out_so_path, '-shared', o_path])
+        call_rc = subprocess.call([C_BIN, "-o", out_so_path, "-shared", o_path])
         if call_rc != 0:
             raise Exception("Failed to compile to a .so file")
 
+    # Re-create symlinks
+    for elt in link_chain:
+        if os.path.exists(elt[0]):
+            if not os.path.islink(elt[0]):
+                raise Exception(
+                    "{}: file already exists and is not a symlink.".format(elt[0])
+                )
+            os.remove(elt[0])
+        os.symlink(elt[1], elt[0])
 
-def gen_all_eh_elf(obj_path, args, dwarf_assembly_args=None):
-    ''' Call `gen_eh_elf` on obj_path and all its dependencies '''
-    if dwarf_assembly_args is None:
-        dwarf_assembly_args = []
 
+def gen_all_eh_elf(obj_path, config):
+    """ Call `gen_eh_elf` on obj_path and all its dependencies """
     deps = elf_so_deps(obj_path)
     deps.append(obj_path)
     for dep in deps:
-        gen_eh_elf(dep, args, dwarf_assembly_args)
+        gen_eh_elf(dep, config)
+
+
+def gen_eh_elfs(obj_path, out_dir, global_switch=True, deps=True, remote=None):
+    """ Call gen{_all,}_eh_elf with args setup accordingly with the given
+    options """
+
+    switch_gen_policy = (
+        SwitchGenPolicy.GLOBAL_SWITCH
+        if global_switch
+        else SwitchGenPolicy.SWITCH_PER_FUNC
+    )
+
+    config = Config(
+        out_dir, [], False, [obj_path], sw_gen_policy=switch_gen_policy, remote=remote
+    )
+
+    if deps:
+        return gen_all_eh_elf([obj_path], config)
+    return gen_eh_elf([obj_path], config)
 
 
 def process_args():
-    ''' Process `sys.argv` arguments '''
+    """ Process `sys.argv` arguments """
 
     parser = argparse.ArgumentParser(
-        description="Compile ELFs into their related eh_elfs",
+        description="Compile ELFs into their related eh_elfs"
     )
 
-    parser.add_argument('--deps', action='store_const',
-                        const=gen_all_eh_elf, default=gen_eh_elf,
-                        dest='gen_func',
-                        help=("Also generate eh_elfs for the shared objects "
-                              "this object depends on"))
-    parser.add_argument('-o', '--output', metavar="path",
-                        help=("Save the generated objects at the given path "
-                              "instead of the current working directory"))
-    parser.add_argument('--remote', metavar='ssh_args',
-                        help=("Execute the heavyweight commands on the remote "
-                              "machine, using `ssh ssh_args`."))
-    parser.add_argument('--use-pc-list', action='store_true',
-                        help=("Generate a PC list using `extract_pc.py` for "
+    parser.add_argument(
+        "--deps",
+        action="store_const",
+        const=gen_all_eh_elf,
+        default=gen_eh_elf,
+        dest="gen_func",
+        help=("Also generate eh_elfs for the shared objects " "this object depends on"),
+    )
+    parser.add_argument(
+        "-o",
+        "--output",
+        metavar="path",
+        help=(
+            "Save the generated objects at the given path "
+            "instead of the current working directory"
+        ),
+    )
+    parser.add_argument(
+        "-a",
+        "--aux",
+        action="append",
+        default=[],
+        help=(
+            "Alternative output directories. These "
+            "directories are searched for existing matching "
+            "eh_elfs, and if found, these files are updated "
+            "instead of creating new files in the --output "
+            "directory. By default, some aux directories "
+            "are always considered, unless -A is passed: "
+            "{}."
+        ).format(Config.default_aux_str()),
+    )
+    parser.add_argument(
+        "-A",
+        "--no-dft-aux",
+        action="store_true",
+        help=("Do not use the default auxiliary output " "directories: {}.").format(
+            Config.default_aux_str()
+        ),
+    )
+    parser.add_argument(
+        "--remote",
+        metavar="ssh_args",
+        help=(
+            "Execute the heavyweight commands on the remote "
+            "machine, using `ssh ssh_args`."
+        ),
+    )
+    parser.add_argument(
+        "--use-pc-list",
+        action="store_true",
+        help=(
+            "Generate a PC list using `extract_pc.py` for "
             "each processed ELF file, and call "
-                              "dwarf-assembly accordingly."))
-    parser.add_argument('--force', '-f', action='store_true',
-                        help=("Force re-generation of the output files, even "
+            "dwarf-assembly accordingly."
+        ),
+    )
+    parser.add_argument(
+        "--force",
+        "-f",
+        action="store_true",
+        help=(
+            "Force re-generation of the output files, even "
             "when those files are newer than the target "
-                              "ELF."))
+            "ELF."
+        ),
+    )
+    parser.add_argument(
+        "--enable-deref-arg",
+        action="store_true",
+        help=(
+            "Pass the `--enable-deref-arg` to "
+            "dwarf-assembly, enabling an extra `deref` "
+            "argument for each lookup function, allowing "
+            "to work on remote address spaces."
+        ),
+    )
+    parser.add_argument(
+        "--keep-holes",
+        action="store_true",
+        help=(
+            "Keep holes between FDEs instead of filling "
+            "them with junk. More accurate, less compact."
+        ),
+    )
+    parser.add_argument(
+        "-g",
+        "--cc-debug",
+        action="store_true",
+        help=("Compile the source file with -g for easy " "debugging"),
+    )
     # c_opt_level
     opt_level_grp = parser.add_mutually_exclusive_group()
-    opt_level_grp.add_argument('-O0', action='store_const', const='-O0',
-                               dest='c_opt_level',
-                               help=("Compile C file with this optimization "
-                                     "level."))
-    opt_level_grp.add_argument('-O1', action='store_const', const='-O1',
-                               dest='c_opt_level',
-                               help=("Compile C file with this optimization "
-                                     "level."))
-    opt_level_grp.add_argument('-O2', action='store_const', const='-O2',
-                               dest='c_opt_level',
-                               help=("Compile C file with this optimization "
-                                     "level."))
-    opt_level_grp.add_argument('-O3', action='store_const', const='-O3',
-                               dest='c_opt_level',
-                               help=("Compile C file with this optimization "
-                                     "level."))
-    opt_level_grp.add_argument('-Os', action='store_const', const='-Os',
-                               dest='c_opt_level',
-                               help=("Compile C file with this optimization "
-                                     "level."))
+    opt_level_grp.add_argument(
+        "-O0",
+        action="store_const",
+        const="0",
+        dest="c_opt_level",
+        help=("Compile C file with this optimization " "level."),
+    )
+    opt_level_grp.add_argument(
+        "-O1",
+        action="store_const",
+        const="1",
+        dest="c_opt_level",
+        help=("Compile C file with this optimization " "level."),
+    )
+    opt_level_grp.add_argument(
+        "-O2",
+        action="store_const",
+        const="2",
+        dest="c_opt_level",
+        help=("Compile C file with this optimization " "level."),
+    )
+    opt_level_grp.add_argument(
+        "-O3",
+        action="store_const",
+        const="3",
+        dest="c_opt_level",
+        help=("Compile C file with this optimization " "level."),
+    )
+    opt_level_grp.add_argument(
+        "-Os",
+        action="store_const",
+        const="s",
+        dest="c_opt_level",
+        help=("Compile C file with this optimization " "level."),
+    )
+    opt_level_grp.set_defaults(c_opt_level="3")
 
-    switch_generation_policy = \
-        parser.add_mutually_exclusive_group(required=True)
-    switch_generation_policy.add_argument('--switch-per-func',
-                                          action='store_const', const='',
-                                          help=("Passed to dwarf-assembly."))
-    switch_generation_policy.add_argument('--global-switch',
-                                          action='store_const', const='',
-                                          help=("Passed to dwarf-assembly."))
-    parser.add_argument('object', nargs='+',
-                        help="The ELF object(s) to process")
+    switch_gen_policy = parser.add_mutually_exclusive_group(required=True)
+    switch_gen_policy.add_argument(
+        "--switch-per-func",
+        dest="sw_gen_policy",
+        action="store_const",
+        const=SwitchGenPolicy.SWITCH_PER_FUNC,
+        help=("Passed to dwarf-assembly."),
+    )
+    switch_gen_policy.add_argument(
+        "--global-switch",
+        dest="sw_gen_policy",
+        action="store_const",
+        const=SwitchGenPolicy.GLOBAL_SWITCH,
+        help=("Passed to dwarf-assembly."),
+    )
+    parser.add_argument("object", nargs="+", help="The ELF object(s) to process")
     return parser.parse_args()
 
 
 def main():
     args = process_args()
-
-    DW_ASSEMBLY_OPTS = {
-        'switch_per_func': '--switch-per-func',
-        'global_switch': '--global-switch',
-    }
-
-    dwarf_assembly_opts = []
-    args_dict = vars(args)
-    for opt in DW_ASSEMBLY_OPTS:
-        if opt in args and args_dict[opt] is not None:
-            dwarf_assembly_opts.append(DW_ASSEMBLY_OPTS[opt])
+    config = Config(
+        output=args.output,
+        aux=args.aux,
+        no_dft_aux=args.no_dft_aux,
+        objects=args.object,
+        sw_gen_policy=args.sw_gen_policy,
+        force=args.force,
+        use_pc_list=args.use_pc_list,
+        c_opt_level=args.c_opt_level,
+        enable_deref_arg=args.enable_deref_arg,
+        keep_holes=args.keep_holes,
+        cc_debug=args.cc_debug,
+        remote=args.remote,
+    )
 
     for obj in args.object:
-        args.gen_func(obj, args, dwarf_assembly_opts)
+        args.gen_func(obj, config)
 
 
 if __name__ == "__main__":

shared/context_struct.h

@@ -1,7 +1,23 @@
 #include <stdint.h>
 
+typedef enum {
+    UNWF_RIP=0,
+    UNWF_RSP=1,
+    UNWF_RBP=2,
+    UNWF_RBX=3,
+
+    UNWF_ERROR=7
+} unwind_flags_t;
+
 typedef struct {
-    uintptr_t rip, rsp, rbp;
+    uint8_t flags;
+    uintptr_t rip, rsp, rbp, rbx;
 } unwind_context_t;
 
+typedef uintptr_t (*deref_func_t)(uintptr_t);
+
 typedef unwind_context_t (*_fde_func_t)(unwind_context_t, uintptr_t);
+typedef unwind_context_t (*_fde_func_with_deref_t)(
+        unwind_context_t,
+        uintptr_t,
+        deref_func_t);

shared_python.py

@@ -6,6 +6,42 @@ import os
 from collections import namedtuple
 
 
+DEFAULT_AUX_DIRS = [
+    '~/.cache/eh_elfs',
+]
+
+
+def to_eh_elf_path(so_path, out_dir, base=False):
+    ''' Transform a library path into its eh_elf counterpart '''
+    base_path = os.path.basename(so_path) + '.eh_elf'
+    if base:
+        return base_path
+    return os.path.join(out_dir, base_path + '.so')
+
+
+def find_eh_elf_dir(obj_path, aux_dirs, out_dir):
+    ''' Find the directory in which the eh_elf corresponding to `obj_path` will
+    be outputted, among the output directory and the aux directories '''
+
+    for candidate in aux_dirs:
+        eh_elf_path = to_eh_elf_path(obj_path, candidate)
+        if os.path.exists(eh_elf_path):
+            return candidate
+
+    # No match among the aux dirs
+    return out_dir
+
+
+def readlink_rec(path):
+    ''' Returns the canonical path of `path`, resolving multiple layers of
+    symlinks '''
+    while os.path.islink(path):
+        path = os.path.join(
+            os.path.dirname(path),
+            os.readlink(path))
+    return path
+
+
 def is_newer(file1, file2):
     ''' Returns True iff file1 is newer than file2 '''
     try:
@@ -52,6 +88,9 @@ def do_remote(remote, command, send_files=None, retr_files=None):
 
     The command is executed on the machine described by `remote` (see ssh(1)).
 
+    If `preload` is set, then the remote file at this path will be sourced
+    before running any command, allowing to set PATH and other variables.
+
     send_files is a list of file paths that must be first copied at the root of
     a temporary directory on `remote` before running the command. Consider
     yourself jailed in that directory.
@@ -64,6 +103,11 @@ def do_remote(remote, command, send_files=None, retr_files=None):
     otherwise, on the local machine.
     '''
 
+    if send_files is None:
+        send_files = []
+    if retr_files is None:
+        retr_files = []
+
     def ssh_do(cmd_args, working_directory=None):
         try:
             cmd = ['ssh', remote]

src/CodeGenerator.cpp

@@ -1,22 +1,54 @@
 #include "CodeGenerator.hpp"
 #include "gen_context_struct.hpp"
 #include "settings.hpp"
+#include "../shared/context_struct.h"
 
 #include <algorithm>
 #include <limits>
+#include <exception>
+#include <sstream>
 
 using namespace std;
 
+class UnhandledRegister: public std::exception {};
+
 static const char* PRELUDE =
 "#include <assert.h>\n"
 "\n"
 ;
 
+struct UnwFlags {
+    UnwFlags():
+        error(false), rip(false), rsp(false), rbp(false), rbx(false) {}
+
+
+    bool error, rip, rsp, rbp, rbx;
+
+    uint8_t to_uint8() const {
+        uint8_t out = 0;
+        if(rip)
+            out |= (1 << UNWF_RIP);
+        if(rsp)
+            out |= (1 << UNWF_RSP);
+        if(rbp)
+            out |= (1 << UNWF_RBP);
+        if(rbx)
+            out |= (1 << UNWF_RBX);
+        if(error)
+            out |= (1 << UNWF_ERROR);
+
+        return out;
+    }
+};
+
+
 CodeGenerator::CodeGenerator(
         const SimpleDwarf& dwarf,
         std::ostream& os,
-        NamingScheme naming_scheme):
-    dwarf(dwarf), os(os), pc_list(nullptr), naming_scheme(naming_scheme)
+        NamingScheme naming_scheme,
+        AbstractSwitchCompiler* sw_compiler) :
+    dwarf(dwarf), os(os), pc_list(nullptr),
+    naming_scheme(naming_scheme), switch_compiler(sw_compiler)
 {
     if(!settings::pc_list.empty()) {
         pc_list = make_unique<PcListReader>(settings::pc_list);
@@ -28,6 +60,41 @@ void CodeGenerator::generate() {
     gen_of_dwarf();
 }
 
+SwitchStatement CodeGenerator::gen_fresh_switch() const {
+    SwitchStatement out;
+    out.switch_var = "pc";
+    ostringstream default_oss;
+    UnwFlags flags;
+    flags.error = true;
+    default_oss
+        << "out_ctx.flags = " << (int) flags.to_uint8() << "u;\n"
+        << "return out_ctx;\n";
+    out.default_case = default_oss.str();
+    return out;
+}
+
+void CodeGenerator::switch_append_fde(
+        SwitchStatement& sw,
+        const SimpleDwarf::Fde& fde) const
+{
+    for(size_t fde_row_id=0; fde_row_id < fde.rows.size(); ++fde_row_id)
+    {
+        SwitchStatement::SwitchCase sw_case;
+
+        uintptr_t up_bound = fde.end_ip - 1;
+        if(fde_row_id != fde.rows.size() - 1)
+            up_bound = fde.rows[fde_row_id + 1].ip - 1;
+        sw_case.low_bound = fde.rows[fde_row_id].ip;
+        sw_case.high_bound = up_bound;
+
+        ostringstream case_oss;
+        gen_of_row_content(fde.rows[fde_row_id], case_oss);
+        sw_case.content.code = case_oss.str();
+
+        sw.cases.push_back(sw_case);
+    }
+}
+
 void CodeGenerator::gen_of_dwarf() {
     os << CONTEXT_STRUCT_STR << '\n'
        << PRELUDE << '\n' << endl;
@@ -55,9 +122,10 @@ void CodeGenerator::gen_of_dwarf() {
         case settings::SGP_GlobalSwitch:
         {
             gen_unwind_func_header("_eh_elf");
-            for(const auto& fde: dwarf.fde_list) {
-                gen_switchpart_of_fde(fde);
-            }
+            SwitchStatement sw_stmt = gen_fresh_switch();
+            for(const auto& fde: dwarf.fde_list)
+                switch_append_fde(sw_stmt, fde);
+            (*switch_compiler)(os, sw_stmt);
             gen_unwind_func_footer();
             break;
         }
@@ -65,84 +133,85 @@ void CodeGenerator::gen_of_dwarf() {
 }
 
 void CodeGenerator::gen_unwind_func_header(const std::string& name) {
+    string deref_arg;
+    if(settings::enable_deref_arg)
+        deref_arg = ", deref_func_t deref";
+
     os << "unwind_context_t "
        << name
-       << "(unwind_context_t ctx, uintptr_t pc) {\n"
-       << "\tunwind_context_t out_ctx;\n"
-       << "\tswitch(pc) {" << endl;
+       << "(unwind_context_t ctx, uintptr_t pc" << deref_arg << ") {\n"
+       << "\tunwind_context_t out_ctx;" << endl;
 }
 
 void CodeGenerator::gen_unwind_func_footer() {
-    os << "\t\tdefault: assert(0);\n"
-       << "\t}\n"
-       << "}" << endl;
+    os << "}" << endl;
 }
 
 void CodeGenerator::gen_function_of_fde(const SimpleDwarf::Fde& fde) {
     gen_unwind_func_header(naming_scheme(fde));
 
-    gen_switchpart_of_fde(fde);
+    SwitchStatement sw_stmt = gen_fresh_switch();
+    switch_append_fde(sw_stmt, fde);
+    (*switch_compiler)(os, sw_stmt);
 
     gen_unwind_func_footer();
 }
 
-void CodeGenerator::gen_switchpart_of_fde(const SimpleDwarf::Fde& fde) {
-    os << "\t\t/********** FDE: 0x" << std::hex << fde.fde_offset
-       << ", PC = 0x" << fde.beg_ip << std::dec << " */" << std::endl;
-    for(size_t fde_row_id=0; fde_row_id < fde.rows.size(); ++fde_row_id)
-    {
-        uintptr_t up_bound = fde.end_ip - 1;
-        if(fde_row_id != fde.rows.size() - 1)
-            up_bound = fde.rows[fde_row_id + 1].ip - 1;
-
-        gen_of_row(fde.rows[fde_row_id], up_bound);
-    }
-}
-
-void CodeGenerator::gen_of_row(
+void CodeGenerator::gen_of_row_content(
         const SimpleDwarf::DwRow& row,
-        uintptr_t row_end)
+        std::ostream& stream) const
 {
-    gen_case(row.ip, row_end);
+    UnwFlags flags;
 
-    os << "\t\t\t" << "out_ctx.rsp = ";
-    gen_of_reg(row.cfa);
-    os << ';' << endl;
-
-    os << "\t\t\t" << "out_ctx.rbp = ";
-    gen_of_reg(row.rbp);
-    os << ';' << endl;
-
-    os << "\t\t\t" << "out_ctx.rip = ";
-    gen_of_reg(row.ra);
-    os << ';' << endl;
-
-    os << "\t\t\treturn " << "out_ctx" << ";" << endl;
+    try {
+        if(!check_reg_valid(row.ra)) {
+            // RA might be undefined (last frame), but if it is defined and we
+            // don't implement it (eg. EXPR), it is an error
+            flags.error = true;
+            goto write_flags;
         }
 
-void CodeGenerator::gen_case(uintptr_t low_bound, uintptr_t high_bound) {
-    if(pc_list == nullptr) {
-        os << "\t\tcase " << std::hex << "0x" << low_bound
-           << " ... 0x" << high_bound << ":" << std::dec << endl;
+        if(check_reg_valid(row.cfa)) {
+            flags.rsp = true;
+            stream << "out_ctx.rsp = ";
+            gen_of_reg(row.cfa, stream);
+            stream << ';' << endl;
         }
-    else {
-        const auto& first_it = lower_bound(
-                pc_list->get_list().begin(),
-                pc_list->get_list().end(),
-                low_bound);
-        const auto& last_it = upper_bound(
-                pc_list->get_list().begin(),
-                pc_list->get_list().end(),
-                high_bound);
-
-        if(first_it == pc_list->get_list().end())
-            throw CodeGenerator::InvalidPcList();
-
-        os << std::hex;
-        for(auto it = first_it; it != last_it; ++it)
-            os << "\t\tcase 0x" << *it << ":\n";
-        os << std::dec;
+        else { // rsp is required (CFA)
+            flags.error = true;
+            goto write_flags;
         }
+
+        if(check_reg_defined(row.rbp)) {
+            flags.rbp = true;
+            stream << "out_ctx.rbp = ";
+            gen_of_reg(row.rbp, stream);
+            stream << ';' << endl;
+        }
+
+        if(check_reg_defined(row.ra)) {
+            flags.rip = true;
+            stream << "out_ctx.rip = ";
+            gen_of_reg(row.ra, stream);
+            stream << ';' << endl;
+        }
+
+        if(check_reg_defined(row.rbx)) {
+            flags.rbx = true;
+            stream << "out_ctx.rbx = ";
+            gen_of_reg(row.rbx, stream);
+            stream << ';' << endl;
+        }
+    } catch(const UnhandledRegister& exn) {
+        // This should not happen, since we check_reg_*, but heh.
+        flags.error = true;
+        stream << ";\n";
+    }
+
+write_flags:
+    stream << "out_ctx.flags = " << (int)flags.to_uint8() << "u;" << endl;
+
+    stream << "return " << "out_ctx" << ";" << endl;
 }
 
 static const char* ctx_of_dw_name(SimpleDwarf::MachineRegister reg) {
@@ -153,28 +222,68 @@ static const char* ctx_of_dw_name(SimpleDwarf::MachineRegister reg) {
             return "ctx.rsp";
         case SimpleDwarf::REG_RBP:
             return "ctx.rbp";
+        case SimpleDwarf::REG_RBX:
+            return "ctx.rbx";
         case SimpleDwarf::REG_RA:
             throw CodeGenerator::NotImplementedCase();
     }
     return "";
 }
 
-void CodeGenerator::gen_of_reg(const SimpleDwarf::DwRegister& reg) {
+bool CodeGenerator::check_reg_defined(
+        const SimpleDwarf::DwRegister& reg) const
+{
     switch(reg.type) {
         case SimpleDwarf::DwRegister::REG_UNDEFINED:
-            os << std::numeric_limits<uintptr_t>::max() << "ull";
+        case SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED:
+            return false;
+        default:
+            return true;
+    }
+}
+bool CodeGenerator::check_reg_valid(const SimpleDwarf::DwRegister& reg) const {
+    return reg.type != SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED;
+}
+
+void CodeGenerator::gen_of_reg(const SimpleDwarf::DwRegister& reg,
+        ostream& stream) const
+{
+    switch(reg.type) {
+        case SimpleDwarf::DwRegister::REG_UNDEFINED:
+            // This function is not supposed to be called on an undefined
+            // register
+            throw UnhandledRegister();
             break;
         case SimpleDwarf::DwRegister::REG_REGISTER:
-            os << ctx_of_dw_name(reg.reg)
+            stream << ctx_of_dw_name(reg.reg)
                 << " + (" << reg.offset << ")";
             break;
-        case SimpleDwarf::DwRegister::REG_CFA_OFFSET:
-            os << "*((uintptr_t*)(out_ctx.rsp + ("
+        case SimpleDwarf::DwRegister::REG_CFA_OFFSET: {
+            if(settings::enable_deref_arg) {
+                stream << "deref(out_ctx.rsp + ("
+                   << reg.offset
+                   << "))";
+            }
+            else {
+                stream << "*((uintptr_t*)(out_ctx.rsp + ("
                    << reg.offset
                    << ")))";
+            }
             break;
+        }
+        case SimpleDwarf::DwRegister::REG_PLT_EXPR: {
+            /*
+            if(settings::enable_deref_arg)
+                stream << "(deref(";
+            else
+                stream << "*((uintptr_t*)(";
+            */
+            stream << "(((ctx.rip & 15) >= 11) ? 8 : 0) + ctx.rsp";
+            break;
+        }
         case SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED:
-            os << "0; assert(0)";
+            stream << "0";
+            throw UnhandledRegister();
             break;
     }
 }

src/CodeGenerator.hpp

@@ -8,6 +8,7 @@
 
 #include "SimpleDwarf.hpp"
 #include "PcListReader.hpp"
+#include "SwitchStatement.hpp"
 
 class CodeGenerator {
     public:
@@ -23,7 +24,8 @@ class CodeGenerator {
         /** Create a CodeGenerator to generate code for the given dwarf, on the
          * given std::ostream object (eg. cout). */
         CodeGenerator(const SimpleDwarf& dwarf, std::ostream& os,
-                NamingScheme naming_scheme);
+                NamingScheme naming_scheme,
+                AbstractSwitchCompiler* sw_compiler);
 
         /// Actually generate the code on the given stream
         void generate();
@@ -34,24 +36,33 @@ class CodeGenerator {
             uintptr_t beg, end;
         };
 
+
+        SwitchStatement gen_fresh_switch() const;
+        void switch_append_fde(
+                SwitchStatement& sw,
+                const SimpleDwarf::Fde& fde) const;
         void gen_of_dwarf();
         void gen_unwind_func_header(const std::string& name);
         void gen_unwind_func_footer();
         void gen_function_of_fde(const SimpleDwarf::Fde& fde);
-        void gen_switchpart_of_fde(const SimpleDwarf::Fde& fde);
-        void gen_of_row(
+        void gen_of_row_content(
                 const SimpleDwarf::DwRow& row,
-                uintptr_t row_end);
-        void gen_case(uintptr_t low_bound, uintptr_t high_bound);
+                std::ostream& stream) const;
         void gen_of_reg(
-                const SimpleDwarf::DwRegister& reg);
+                const SimpleDwarf::DwRegister& reg,
+                std::ostream& stream) const;
 
         void gen_lookup(const std::vector<LookupEntry>& entries);
 
+        bool check_reg_defined(const SimpleDwarf::DwRegister& reg) const;
+        bool check_reg_valid(const SimpleDwarf::DwRegister& reg) const;
+
     private:
         SimpleDwarf dwarf;
         std::ostream& os;
         std::unique_ptr<PcListReader> pc_list;
 
         NamingScheme naming_scheme;
+
+        std::unique_ptr<AbstractSwitchCompiler> switch_compiler;
 };

src/ConseqEquivFilter.cpp

@@ -0,0 +1,50 @@
+#include "ConseqEquivFilter.hpp"
+
+using namespace std;
+
+ConseqEquivFilter::ConseqEquivFilter(bool enable): SimpleDwarfFilter(enable) {}
+
+static bool equiv_reg(
+        const SimpleDwarf::DwRegister& r1,
+        const SimpleDwarf::DwRegister& r2)
+{
+    return r1.type == r2.type
+        && r1.offset == r2.offset
+        && r1.reg == r2.reg;
+}
+
+static bool equiv_row(
+        const SimpleDwarf::DwRow& r1,
+        const SimpleDwarf::DwRow& r2)
+{
+    return r1.ip == r2.ip
+        && equiv_reg(r1.cfa, r2.cfa)
+        && equiv_reg(r1.rbp, r2.rbp)
+        && equiv_reg(r1.rbx, r2.rbx)
+        && equiv_reg(r1.ra, r2.ra);
+}
+
+SimpleDwarf ConseqEquivFilter::do_apply(const SimpleDwarf& dw) const {
+    SimpleDwarf out;
+
+    for(const auto& fde: dw.fde_list) {
+        out.fde_list.push_back(SimpleDwarf::Fde());
+        SimpleDwarf::Fde& cur_fde = out.fde_list.back();
+        cur_fde.fde_offset = fde.fde_offset;
+        cur_fde.beg_ip = fde.beg_ip;
+        cur_fde.end_ip = fde.end_ip;
+
+        if(fde.rows.empty())
+            continue;
+
+        cur_fde.rows.push_back(fde.rows.front());
+        for(size_t pos=1; pos < fde.rows.size(); ++pos) {
+            const auto& row = fde.rows[pos];
+            if(!equiv_row(row, cur_fde.rows.back())) {
+                cur_fde.rows.push_back(row);
+            }
+        }
+    }
+
+    return out;
+}

src/ConseqEquivFilter.hpp

@@ -0,0 +1,16 @@
+/** SimpleDwarfFilter to keep a unique Dwarf row for each group of consecutive
+ * lines that are equivalent, that is, that share the same considered
+ * registers' values. */
+
+#pragma once
+
+#include "SimpleDwarf.hpp"
+#include "SimpleDwarfFilter.hpp"
+
+class ConseqEquivFilter: public SimpleDwarfFilter {
+    public:
+        ConseqEquivFilter(bool enable=true);
+
+    private:
+        SimpleDwarf do_apply(const SimpleDwarf& dw) const;
+};

src/DwarfReader.cpp

@@ -1,5 +1,7 @@
 #include "DwarfReader.hpp"
 
+#include "plt_std_expr.hpp"
+
 #include <fstream>
 #include <fileno.hpp>
 #include <set>
@@ -7,14 +9,25 @@
 using namespace std;
 using namespace dwarf;
 
-typedef std::set<std::pair<int, core::FrameSection::register_def> >
-    dwarfpp_row_t;
-
 DwarfReader::DwarfReader(const string& path):
     root(fileno(ifstream(path)))
 {}
 
-SimpleDwarf DwarfReader::read() const {
+// Debug function -- dumps an expression
+static void dump_expr(const core::FrameSection::register_def& reg) {
+    assert(reg.k == core::FrameSection::register_def::SAVED_AT_EXPR
+           || reg.k == core::FrameSection::register_def::VAL_OF_EXPR);
+
+    const encap::loc_expr& expr = reg.saved_at_expr_r();
+
+    for(const auto& elt: expr) {
+        fprintf(stderr, "(%02x, %02llx, %02llx, %02llx) :: ",
+                elt.lr_atom, elt.lr_number, elt.lr_number2, elt.lr_offset);
+    }
+    fprintf(stderr, "\n");
+}
+
+SimpleDwarf DwarfReader::read() {
     const core::FrameSection& fs = root.get_frame_section();
     SimpleDwarf output;
 
@@ -26,46 +39,51 @@ SimpleDwarf DwarfReader::read() const {
     return output;
 }
 
-SimpleDwarf::Fde DwarfReader::read_fde(const core::Fde& fde) const {
-    SimpleDwarf::Fde output;
-    output.fde_offset = fde.get_fde_offset();
-    output.beg_ip = fde.get_low_pc();
-    output.end_ip = fde.get_low_pc() + fde.get_func_length();
-
-    auto rows = fde.decode().rows;
-    const core::Cie& cie = *fde.find_cie();
-    int ra_reg = cie.get_return_address_register_rule();
-
-    for(const auto row_pair: rows) {
-        SimpleDwarf::DwRow cur_row;
-
-        cur_row.ip = row_pair.first.lower();
-
-        const dwarfpp_row_t& row = row_pair.second;
-
-        for(const auto& cell: row) {
-            if(cell.first == DW_FRAME_CFA_COL3) {
-                cur_row.cfa = read_register(cell.second);
+void DwarfReader::add_cell_to_row(
+        const dwarf::core::FrameSection::register_def& reg,
+        int reg_id,
+        int ra_reg,
+        SimpleDwarf::DwRow& cur_row)
+{
+    if(reg_id == DW_FRAME_CFA_COL3) {
+        cur_row.cfa = read_register(reg);
     }
     else {
         try {
             SimpleDwarf::MachineRegister reg_type =
-                        from_dwarfpp_reg(cell.first, ra_reg);
+                from_dwarfpp_reg(reg_id, ra_reg);
             switch(reg_type) {
                 case SimpleDwarf::REG_RBP:
-                            cur_row.rbp = read_register(cell.second);
+                    cur_row.rbp = read_register(reg);
+                    break;
+                case SimpleDwarf::REG_RBX:
+                    cur_row.rbx = read_register(reg);
                     break;
                 case SimpleDwarf::REG_RA:
-                            cur_row.ra = read_register(cell.second);
+                    cur_row.ra = read_register(reg);
                     break;
                 default:
                     break;
             }
         }
-                catch(UnsupportedRegister) {} // Just ignore it.
+        catch(const UnsupportedRegister&) {} // Just ignore it.
     }
 }
 
+void DwarfReader::append_row_to_fde(
+        const dwarfpp_row_t& row,
+        uintptr_t row_addr,
+        int ra_reg,
+        SimpleDwarf::Fde& output)
+{
+    SimpleDwarf::DwRow cur_row;
+
+    cur_row.ip = row_addr;
+
+    for(const auto& cell: row) {
+        add_cell_to_row(cell.second, cell.first, ra_reg, cur_row);
+    }
+
     if(cur_row.cfa.type == SimpleDwarf::DwRegister::REG_UNDEFINED)
     {
         // Not set
@@ -75,6 +93,66 @@ SimpleDwarf::Fde DwarfReader::read_fde(const core::Fde& fde) const {
     output.rows.push_back(cur_row);
 }
 
+template<typename Key, typename Value>
+static std::set<std::pair<Key, Value> > map_to_setpair(
+        const std::map<Key, Value>& src_map)
+{
+    std::set<std::pair<Key, Value> > out;
+    for(const auto map_it: src_map) {
+        out.insert(map_it);
+    }
+    return out;
+}
+
+void DwarfReader::append_results_to_fde(
+        const dwarf::core::FrameSection::instrs_results& results,
+        int ra_reg,
+        SimpleDwarf::Fde& output)
+{
+    for(const auto row_pair: results.rows) {
+        append_row_to_fde(
+                row_pair.second,
+                row_pair.first.lower(),
+                ra_reg,
+                output);
+    }
+    if(results.unfinished_row.size() > 0) {
+        try {
+            append_row_to_fde(
+                    map_to_setpair(results.unfinished_row),
+                    results.unfinished_row_addr,
+                    ra_reg,
+                    output);
+        } catch(const InvalidDwarf&) {
+            // Ignore: the unfinished_row can be undefined
+        }
+    }
+}
+
+SimpleDwarf::Fde DwarfReader::read_fde(const core::Fde& fde) {
+    SimpleDwarf::Fde output;
+    output.fde_offset = fde.get_fde_offset();
+    output.beg_ip = fde.get_low_pc();
+    output.end_ip = fde.get_low_pc() + fde.get_func_length();
+
+    const core::Cie& cie = *fde.find_cie();
+    int ra_reg = cie.get_return_address_register_rule();
+
+    // CIE rows
+    core::FrameSection cie_fs(root.get_dbg(), true);
+    auto cie_rows = cie_fs.interpret_instructions(
+            cie,
+            fde.get_low_pc(),
+            cie.get_initial_instructions(),
+            cie.get_initial_instructions_length());
+
+    // FDE rows
+    auto fde_rows = fde.decode();
+
+    // instrs
+    append_results_to_fde(cie_rows, ra_reg, output);
+    append_results_to_fde(fde_rows, ra_reg, output);
+
     return output;
 }
 
@@ -104,6 +182,13 @@ SimpleDwarf::DwRegister DwarfReader::read_register(
                 output.type = SimpleDwarf::DwRegister::REG_UNDEFINED;
                 break;
 
+            case core::FrameSection::register_def::SAVED_AT_EXPR:
+                if(is_plt_expr(reg))
+                    output.type = SimpleDwarf::DwRegister::REG_PLT_EXPR;
+                else if(!interpret_simple_expr(reg, output))
+                    output.type = SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED;
+                break;
+
             default:
                 output.type = SimpleDwarf::DwRegister::REG_NOT_IMPLEMENTED;
                 break;
@@ -130,7 +215,76 @@ SimpleDwarf::MachineRegister DwarfReader::from_dwarfpp_reg(
             return SimpleDwarf::REG_RSP;
         case lib::DWARF_X86_64_RBP:
             return SimpleDwarf::REG_RBP;
+        case lib::DWARF_X86_64_RBX:
+            return SimpleDwarf::REG_RBX;
         default:
             throw UnsupportedRegister();
     }
 }
+
+static bool compare_dw_expr(
+        const encap::loc_expr& e1,
+        const encap::loc_expr& e2)
+{
+    const std::vector<encap::expr_instr>& e1_vec =
+        static_cast<const vector<encap::expr_instr>&>(e1);
+    const std::vector<encap::expr_instr>& e2_vec =
+        static_cast<const vector<encap::expr_instr>&>(e2);
+
+    return e1_vec == e2_vec;
+}
+
+bool DwarfReader::is_plt_expr(
+        const core::FrameSection::register_def& reg) const
+{
+    if(reg.k != core::FrameSection::register_def::SAVED_AT_EXPR)
+        return false;
+    const encap::loc_expr& expr = reg.saved_at_expr_r();
+
+    bool res = compare_dw_expr(expr, REFERENCE_PLT_EXPR);
+    return res;
+}
+
+bool DwarfReader::interpret_simple_expr(
+        const dwarf::core::FrameSection::register_def& reg,
+        SimpleDwarf::DwRegister& output
+        ) const
+{
+    bool deref = false;
+    if(reg.k == core::FrameSection::register_def::SAVED_AT_EXPR)
+        deref = true;
+    else if(reg.k == core::FrameSection::register_def::VAL_OF_EXPR)
+        deref = false;
+    else
+        return false;
+
+    const encap::loc_expr& expr = reg.saved_at_expr_r();
+    if(expr.size() > 2 || expr.empty())
+        return false;
+
+    const auto& exp_reg = expr[0];
+    if(0x70 <= exp_reg.lr_atom && exp_reg.lr_atom <= 0x8f) { // DW_OP_breg<n>
+        int reg_id = exp_reg.lr_atom - 0x70;
+        try {
+            output.reg = from_dwarfpp_reg(reg_id, -1); // Cannot be CFA anyway
+            output.offset = exp_reg.lr_number;
+        } catch(const UnsupportedRegister& /* exn */) {
+            return false; // Unsupported register
+        }
+    }
+
+    if(expr.size() == 2) { // OK if deref
+        if(expr[1].lr_atom == 0x06) { // deref
+            if(deref)
+                return false;
+            deref = true;
+        }
+        else
+            return false;
+    }
+
+    if(deref)
+        return false; // TODO try stats? Mabye it's worth implementing
+    output.type = SimpleDwarf::DwRegister::REG_REGISTER;
+    return true;
+}

src/DwarfReader.hpp

@@ -13,6 +13,9 @@
 
 #include "SimpleDwarf.hpp"
 
+typedef std::set<std::pair<int, dwarf::core::FrameSection::register_def> >
+    dwarfpp_row_t;
+
 class DwarfReader {
     public:
         class InvalidDwarf: public std::exception {};
@@ -21,19 +24,44 @@ class DwarfReader {
         DwarfReader(const std::string& path);
 
         /** Actually read the ELF file, generating a `SimpleDwarf` output. */
-        SimpleDwarf read() const;
+        SimpleDwarf read();
 
     private: //meth
-        SimpleDwarf::Fde read_fde(const dwarf::core::Fde& fde) const;
+        SimpleDwarf::Fde read_fde(const dwarf::core::Fde& fde);
+
+        void append_results_to_fde(
+                const dwarf::core::FrameSection::instrs_results& results,
+                int ra_reg,
+                SimpleDwarf::Fde& output);
 
         SimpleDwarf::DwRegister read_register(
                 const dwarf::core::FrameSection::register_def& reg) const;
 
+        void add_cell_to_row(
+                const dwarf::core::FrameSection::register_def& reg,
+                int reg_id,
+                int ra_reg,
+                SimpleDwarf::DwRow& cur_row);
+
+        void append_row_to_fde(
+                const dwarfpp_row_t& row,
+                uintptr_t row_addr,
+                int ra_reg,
+                SimpleDwarf::Fde& output);
+
         SimpleDwarf::MachineRegister from_dwarfpp_reg(
                 int reg_id,
                 int ra_reg=-1
                 ) const;
 
+        bool is_plt_expr(
+                const dwarf::core::FrameSection::register_def& reg) const;
+
+        bool interpret_simple_expr(
+                const dwarf::core::FrameSection::register_def& reg,
+                SimpleDwarf::DwRegister& output
+                ) const;
+
         class UnsupportedRegister: public std::exception {};
 
     private:

src/EmptyFdeDeleter.cpp

@@ -0,0 +1,21 @@
+#include "EmptyFdeDeleter.hpp"
+
+#include <algorithm>
+#include <cstdio>
+
+using namespace std;
+
+EmptyFdeDeleter::EmptyFdeDeleter(bool enable): SimpleDwarfFilter(enable) {}
+
+SimpleDwarf EmptyFdeDeleter::do_apply(const SimpleDwarf& dw) const {
+    SimpleDwarf out(dw);
+
+    auto fde = out.fde_list.begin();
+    while(fde != out.fde_list.end()) {
+        if(fde->rows.empty())
+            fde = out.fde_list.erase(fde);
+        else
+            ++fde;
+    }
+    return out;
+}

src/EmptyFdeDeleter.hpp

@@ -0,0 +1,15 @@
+/** Deletes empty FDEs (that is, FDEs with no rows) from the FDEs collection.
+ * This is used to ensure they do not interfere with PcHoleFiller and such. */
+
+#pragma once
+
+#include "SimpleDwarf.hpp"
+#include "SimpleDwarfFilter.hpp"
+
+class EmptyFdeDeleter: public SimpleDwarfFilter {
+    public:
+        EmptyFdeDeleter(bool enable=true);
+
+    private:
+        SimpleDwarf do_apply(const SimpleDwarf& dw) const;
+};

src/FactoredSwitchCompiler.cpp

@@ -0,0 +1,133 @@
+#include "FactoredSwitchCompiler.hpp"
+
+#include <sstream>
+#include <string>
+#include <iostream>
+using namespace std;
+
+FactoredSwitchCompiler::FactoredSwitchCompiler(int indent):
+    AbstractSwitchCompiler(indent), cur_label_id(0)
+{
+}
+
+void FactoredSwitchCompiler::to_stream(
+        std::ostream& os, const SwitchStatement& sw)
+{
+    if(sw.cases.empty()) {
+        std::cerr << "WARNING: empty unwinding data!\n";
+        os
+            << indent_str("/* WARNING: empty unwinding data! */\n")
+            << indent_str(sw.default_case) << "\n";
+        return;
+    }
+    JumpPointMap jump_points;
+
+    uintptr_t low_bound = sw.cases.front().low_bound,
+              high_bound = sw.cases.back().high_bound;
+
+    os << indent() << "if("
+       << "0x" << hex << low_bound << " <= " << sw.switch_var
+       << " && " << sw.switch_var << " <= 0x" << high_bound << dec << ") {\n";
+    indent_count++;
+
+    gen_binsearch_tree(os, jump_points, sw.switch_var,
+            sw.cases.begin(), sw.cases.end(),
+            make_pair(low_bound, high_bound));
+
+    indent_count--;
+    os << indent() << "}\n";
+
+    os << indent() << "_factor_default:\n"
+       << indent_str(sw.default_case) << "\n"
+       << indent() << "/* ===== LABELS  ============================== */\n\n";
+
+    gen_jump_points_code(os, jump_points);
+}
+
+FactoredSwitchCompiler::FactorJumpPoint
+FactoredSwitchCompiler::get_jump_point(
+        FactoredSwitchCompiler::JumpPointMap& jump_map,
+        const SwitchStatement::SwitchCaseContent& sw_case)
+{
+#ifdef STATS
+    stats.refer_count++;
+#endif//STATS
+
+    auto pregen = jump_map.find(sw_case);
+    if(pregen != jump_map.end()) // Was previously generated
+        return pregen->second;
+
+#ifdef STATS
+    stats.generated_count++;
+#endif//STATS
+
+    // Wasn't generated previously -- we'll generate it here
+    size_t label_id = cur_label_id++;
+    ostringstream label_ss;
+    label_ss << "_factor_" << label_id;
+    FactorJumpPoint label_name = label_ss.str();
+
+    jump_map.insert(make_pair(sw_case, label_name));
+    return label_name;
+}
+
+void FactoredSwitchCompiler::gen_jump_points_code(std::ostream& os,
+        const FactoredSwitchCompiler::JumpPointMap& jump_map)
+{
+    for(const auto& block: jump_map) {
+        os << indent() << block.second << ":\n"
+           << indent_str(block.first.code) << "\n\n";
+    }
+    os << indent() << "assert(0);\n";
+}
+
+void FactoredSwitchCompiler::gen_binsearch_tree(
+        std::ostream& os,
+        FactoredSwitchCompiler::JumpPointMap& jump_map,
+        const std::string& sw_var,
+        const FactoredSwitchCompiler::case_iterator_t& begin,
+        const FactoredSwitchCompiler::case_iterator_t& end,
+        const loc_range_t& loc_range)
+{
+    size_t iter_delta = end - begin;
+    if(iter_delta == 0)
+        os << indent() << "assert(0);\n";
+    else if(iter_delta == 1) {
+        FactorJumpPoint jump_point = get_jump_point(
+                jump_map, begin->content);
+        if(loc_range.first < begin->low_bound) {
+            os << indent() << "if(" << sw_var << " < 0x"
+               << hex << begin->low_bound << dec
+               << ") goto _factor_default; "
+               << "// IP=0x" << hex << loc_range.first << " ... 0x"
+               << begin->low_bound - 1 << "\n";
+        }
+        if(begin->high_bound + 1 < loc_range.second) {
+            os << indent() << "if(0x" << hex << begin->high_bound << dec
+               << " < " << sw_var << ") goto _factor_default; "
+               << "// IP=0x" << hex << begin->high_bound + 1 << " ... 0x"
+               << loc_range.second - 1 << "\n";
+        }
+        os << indent() << "// IP=0x" << hex << begin->low_bound
+                       << " ... 0x" << begin->high_bound << dec << "\n"
+           << indent() << "goto " << jump_point << ";\n";
+    }
+    else {
+        const case_iterator_t mid = begin + iter_delta / 2;
+
+        os << indent() << "if(" << sw_var << " < 0x"
+           << hex << mid->low_bound << dec << ") {\n";
+        indent_count++;
+        gen_binsearch_tree(
+                os, jump_map, sw_var, begin, mid,
+                make_pair(loc_range.first, mid->low_bound));
+        indent_count--;
+        os << indent() << "} else {\n";
+        indent_count++;
+        gen_binsearch_tree(
+                os, jump_map, sw_var, mid, end,
+                make_pair(mid->low_bound, loc_range.second));
+        indent_count--;
+        os << indent() << "}\n";
+    }
+}

src/FactoredSwitchCompiler.hpp

@@ -0,0 +1,52 @@
+/** A switch generator that tries to factor out most of the redundancy between
+ * switch blocks, generating manually a switch-like template */
+
+#pragma once
+
+#include "SwitchStatement.hpp"
+#include <map>
+
+class FactoredSwitchCompiler: public AbstractSwitchCompiler {
+    public:
+#ifdef STATS
+        struct Stats {
+            Stats(): generated_count(0), refer_count(0) {}
+            int generated_count, refer_count;
+        };
+
+        const Stats& get_stats() const { return stats; }
+#endif
+        FactoredSwitchCompiler(int indent=0);
+
+    private:
+        typedef std::string FactorJumpPoint;
+        typedef std::map<SwitchStatement::SwitchCaseContent, FactorJumpPoint>
+            JumpPointMap;
+        typedef std::vector<SwitchStatement::SwitchCase>::const_iterator
+            case_iterator_t;
+        typedef std::pair<uintptr_t, uintptr_t> loc_range_t;
+
+    private:
+        virtual void to_stream(std::ostream& os, const SwitchStatement& sw);
+
+        FactorJumpPoint get_jump_point(JumpPointMap& jump_map,
+                const SwitchStatement::SwitchCaseContent& sw_case);
+
+        void gen_jump_points_code(std::ostream& os,
+                const JumpPointMap& jump_map);
+
+        void gen_binsearch_tree(
+                std::ostream& os,
+                JumpPointMap& jump_map,
+                const std::string& sw_var,
+                const case_iterator_t& begin,
+                const case_iterator_t& end,
+                const loc_range_t& loc_range // [beg, end[
+                );
+
+        size_t cur_label_id;
+
+#ifdef STATS
+        Stats stats;
+#endif//STATS
+};

src/Makefile

@@ -1,7 +1,8 @@
 CXX=g++
 CXXLOCS?=-L. -I.
-CXXFLAGS=$(CXXLOCS) -Wall -Wextra -std=c++14 -O2 -g
-CXXLIBS=-lelf -ldwarf -ldwarfpp -lsrk31c++ -lc++fileno
+CXXFL?=
+CXXFLAGS=$(CXXLOCS) -Wall -Wextra -std=c++14 -O2 -g $(CXXFL)
+CXXLIBS=-ldwarf -ldwarfpp -lsrk31c++ -lc++fileno -lelf
 
 TARGET=dwarf-assembly
 OBJS=\
@@ -9,6 +10,14 @@ OBJS=\
 	SimpleDwarf.o \
 	CodeGenerator.o \
 	PcListReader.o \
+	SimpleDwarfFilter.o \
+	PcHoleFiller.o \
+	EmptyFdeDeleter.o \
+	ConseqEquivFilter.o \
+	OverriddenRowFilter.o \
+	SwitchStatement.o \
+	NativeSwitchCompiler.o \
+	FactoredSwitchCompiler.o \
 	settings.o \
 	main.o
 

src/NativeSwitchCompiler.cpp

@@ -0,0 +1,29 @@
+#include "NativeSwitchCompiler.hpp"
+
+using namespace std;
+
+NativeSwitchCompiler::NativeSwitchCompiler(
+        int indent):
+    AbstractSwitchCompiler(indent)
+{}
+
+void NativeSwitchCompiler::to_stream(ostream& os, const SwitchStatement& sw) {
+    os << indent() << "switch(" << sw.switch_var << ") {\n";
+    indent_count++;
+
+    for(const auto& cur_case: sw.cases) {
+        os << indent() << "case 0x"
+           << hex << cur_case.low_bound << " ... 0x" << cur_case.high_bound
+           << dec << ":\n";
+        indent_count++;
+        os << indent_str(cur_case.content.code);
+        indent_count--;
+    }
+
+    os << indent() << "default:\n";
+    indent_count++;
+    os << indent_str(sw.default_case);
+    indent_count--;
+    os << indent() << "}\n";
+    indent_count--;
+}

src/NativeSwitchCompiler.hpp

@@ -0,0 +1,12 @@
+/** Compiles a SwitchStatement to a native C switch */
+
+#pragma once
+
+#include "SwitchStatement.hpp"
+
+class NativeSwitchCompiler: public AbstractSwitchCompiler {
+    public:
+        NativeSwitchCompiler(int indent=0);
+    private:
+        virtual void to_stream(std::ostream& os, const SwitchStatement& sw);
+};

src/OverriddenRowFilter.cpp

@@ -0,0 +1,31 @@
+#include "OverriddenRowFilter.hpp"
+
+OverriddenRowFilter::OverriddenRowFilter(bool enable)
+    : SimpleDwarfFilter(enable)
+{}
+
+SimpleDwarf OverriddenRowFilter::do_apply(const SimpleDwarf& dw) const {
+    SimpleDwarf out;
+
+    for(const auto& fde: dw.fde_list) {
+        out.fde_list.push_back(SimpleDwarf::Fde());
+        SimpleDwarf::Fde& cur_fde = out.fde_list.back();
+        cur_fde.fde_offset = fde.fde_offset;
+        cur_fde.beg_ip = fde.beg_ip;
+        cur_fde.end_ip = fde.end_ip;
+
+        if(fde.rows.empty())
+            continue;
+
+        for(size_t pos=0; pos < fde.rows.size(); ++pos) {
+            const auto& row = fde.rows[pos];
+            if(pos == fde.rows.size() - 1
+                    || row.ip != fde.rows[pos+1].ip)
+            {
+                cur_fde.rows.push_back(row);
+            }
+        }
+    }
+
+    return out;
+}

src/OverriddenRowFilter.hpp

@@ -0,0 +1,15 @@
+/** SimpleDwarfFilter to remove the first `n-1` rows of a block of `n`
+ * contiguous rows that have the exact same address. */
+
+#pragma once
+
+#include "SimpleDwarf.hpp"
+#include "SimpleDwarfFilter.hpp"
+
+class OverriddenRowFilter: public SimpleDwarfFilter {
+    public:
+        OverriddenRowFilter(bool enable=true);
+
+    private:
+        SimpleDwarf do_apply(const SimpleDwarf& dw) const;
+};

src/PcHoleFiller.cpp

@@ -0,0 +1,26 @@
+#include "PcHoleFiller.hpp"
+
+#include <algorithm>
+#include <cstdio>
+
+using namespace std;
+
+PcHoleFiller::PcHoleFiller(bool enable): SimpleDwarfFilter(enable) {}
+
+SimpleDwarf PcHoleFiller::do_apply(const SimpleDwarf& dw) const {
+    SimpleDwarf out(dw);
+    sort(out.fde_list.begin(), out.fde_list.end(),
+            [](const SimpleDwarf::Fde& a, const SimpleDwarf::Fde& b) {
+                return a.beg_ip < b.beg_ip;
+            });
+
+    for(size_t pos=0; pos < out.fde_list.size() - 1; ++pos) {
+        if(out.fde_list[pos].end_ip > out.fde_list[pos + 1].beg_ip) {
+            fprintf(stderr, "WARNING: FDE %016lx-%016lx and %016lx-%016lx\n",
+                    out.fde_list[pos].beg_ip, out.fde_list[pos].end_ip,
+                    out.fde_list[pos + 1].beg_ip, out.fde_list[pos + 1].end_ip);
+        }
+        out.fde_list[pos].end_ip = out.fde_list[pos + 1].beg_ip;
+    }
+    return out;
+}

src/PcHoleFiller.hpp

@@ -0,0 +1,15 @@
+/** Ensures there is no "hole" between two consecutive PC ranges, to optimize
+ * generated code size. */
+
+#pragma once
+
+#include "SimpleDwarf.hpp"
+#include "SimpleDwarfFilter.hpp"
+
+class PcHoleFiller: public SimpleDwarfFilter {
+    public:
+        PcHoleFiller(bool enable=true);
+
+    private:
+        SimpleDwarf do_apply(const SimpleDwarf& dw) const;
+};

src/README.md

@@ -23,3 +23,20 @@ a list of all PCs in the ELF. The file contains one 8-bytes chunk per PC,
 which is the PC in little endian.
 
 `--pc-list PC_LIST_FILE_PATH`
+
+### Dereferencing function
+
+The lookup functions can also take an additional argument, a pointer to a
+function of prototype
+
+```C
+  uintptr_t deref(uintptr_t address)
+```
+
+that will, in spirit, contain a `return *((uintptr_t*)address);`.
+
+This argument can be used to work on remote address spaces instead of local
+address spaces, eg. to work with `libunwind`.
+
+To enable the presence of this argument, you must pass the option
+`--enable-deref-arg`

src/SimpleDwarf.cpp

@@ -1,4 +1,15 @@
 #include "SimpleDwarf.hpp"
+#include "../shared/context_struct.h"
+
+uint8_t SimpleDwarf::to_shared_flag(SimpleDwarf::MachineRegister mreg) {
+    switch(mreg) {
+        case REG_RIP: return (1 << UNWF_RIP);
+        case REG_RSP: return (1 << UNWF_RSP);
+        case REG_RBP: return (1 << UNWF_RBP);
+        case REG_RBX: return (1 << UNWF_RBX);
+        default:      return 0;
+    }
+}
 
 static std::ostream& operator<<(
         std::ostream& out,
@@ -14,6 +25,9 @@ static std::ostream& operator<<(
         case SimpleDwarf::REG_RBP:
             out << "rbp";
             break;
+        case SimpleDwarf::REG_RBX:
+            out << "rbx";
+            break;
         case SimpleDwarf::REG_RA:
             out << "RA";
             break;
@@ -49,6 +63,7 @@ std::ostream& operator<<(std::ostream& out, const SimpleDwarf::DwRow& row) {
     out << std::hex << row.ip << std::dec
         << '\t' << row.cfa
         << '\t' << row.rbp
+        << '\t' << row.rbx
         << '\t' << row.ra;
     out << std::endl;
     return out;

src/SimpleDwarf.hpp

@@ -13,12 +13,14 @@
 struct SimpleDwarf {
     /** A machine register (eg. %rip) among the supported ones (x86_64 only
      * for now) */
-    static const std::size_t HANDLED_REGISTERS_COUNT = 4;
+    static const std::size_t HANDLED_REGISTERS_COUNT = 5;
     enum MachineRegister {
-        REG_RIP, REG_RSP, REG_RBP,
+        REG_RIP, REG_RSP, REG_RBP, REG_RBX,
         REG_RA ///< A bit of cheating: not a machine register
     };
 
+    static uint8_t to_shared_flag(MachineRegister mreg);
+
     struct DwRegister {
         /** Holds a single Dwarf register value */
 
@@ -30,6 +32,10 @@ struct SimpleDwarf {
                              defined at some later IP in the same DIE) */
             REG_REGISTER, ///< Value of a machine register plus offset
             REG_CFA_OFFSET, ///< Value stored at some offset from CFA
+            REG_PLT_EXPR, /**< Value is the evaluation of the standard PLT
+                            expression, ie `((rip & 15) >= 11) >> 3 + rsp`
+                            This is hardcoded because it's the only expression
+                            found so far, thus worth implementing. */
             REG_NOT_IMPLEMENTED ///< This type of register is not supported
         };
 
@@ -44,6 +50,7 @@ struct SimpleDwarf {
         uintptr_t ip; ///< Instruction pointer
         DwRegister cfa; ///< Canonical Frame Address
         DwRegister rbp; ///< Base pointer register
+        DwRegister rbx; ///< RBX, sometimes used for unwinding
         DwRegister ra; ///< Return address
 
         friend std::ostream& operator<<(std::ostream &, const DwRow&);
@@ -51,8 +58,8 @@ struct SimpleDwarf {
 
     struct Fde {
         uintptr_t fde_offset; ///< This FDE's offset in the original DWARF
-        uintptr_t beg_ip, ///< This FDE's start instruction pointer
-                  end_ip; ///< This FDE's end instruction pointer
+        uintptr_t beg_ip, ///< This FDE's start instruction pointer incl.
+                  end_ip; ///< This FDE's end instruction pointer excl.
         std::vector<DwRow> rows; ///< Dwarf rows for this FDE
 
         friend std::ostream& operator<<(std::ostream &, const Fde&);

src/SimpleDwarfFilter.cpp

@@ -0,0 +1,14 @@
+#include "SimpleDwarfFilter.hpp"
+
+SimpleDwarfFilter::SimpleDwarfFilter(bool enable): enable(enable)
+{}
+
+SimpleDwarf SimpleDwarfFilter::apply(const SimpleDwarf& dw) const {
+    if(!enable)
+        return dw;
+    return do_apply(dw);
+}
+
+SimpleDwarf SimpleDwarfFilter::operator()(const SimpleDwarf& dw) {
+    return apply(dw);
+}

src/SimpleDwarfFilter.hpp

@@ -0,0 +1,28 @@
+/** An abstract parent class for any SimpleDwarf filter, that is. a class that
+ * transforms some SimpleDwarf into some other SimpleDwarf. */
+
+#pragma once
+
+#include <vector>
+
+#include "SimpleDwarf.hpp"
+
+class SimpleDwarfFilter {
+    public:
+        /** Constructor
+         *
+         * @param apply set to false to disable this filter. This setting is
+         * convenient for compact filter-chaining code. */
+        SimpleDwarfFilter(bool enable=true);
+
+        /// Applies the filter
+        SimpleDwarf apply(const SimpleDwarf& dw) const;
+
+        /// Same as apply()
+        SimpleDwarf operator()(const SimpleDwarf& dw);
+
+    private:
+        virtual SimpleDwarf do_apply(const SimpleDwarf& dw) const = 0;
+
+        bool enable;
+};

src/SwitchStatement.cpp

@@ -0,0 +1,48 @@
+#include "SwitchStatement.hpp"
+
+#include <sstream>
+
+using namespace std;
+
+AbstractSwitchCompiler::AbstractSwitchCompiler(
+        int indent)
+    : indent_count(indent)
+{
+}
+
+void AbstractSwitchCompiler::operator()(
+        ostream& os, const SwitchStatement& sw)
+{
+    to_stream(os, sw);
+}
+
+string AbstractSwitchCompiler::operator()(const SwitchStatement& sw) {
+    ostringstream os;
+    (*this)(os, sw);
+    return os.str();
+}
+
+std::string AbstractSwitchCompiler::indent_str(const std::string& str) {
+    ostringstream out;
+
+    int last_find = -1;
+    size_t find_pos;
+    while((find_pos = str.find('\n', last_find + 1)) != string::npos) {
+        out << indent()
+            << str.substr(last_find + 1, find_pos - last_find); // includes \n
+        last_find = find_pos;
+    }
+    if(last_find + 1 < (ssize_t)str.size()) {
+        out << indent()
+            << str.substr(last_find + 1)
+            << '\n';
+    }
+    return out.str();
+}
+
+std::string AbstractSwitchCompiler::indent() const {
+    return string(indent_count, '\t');
+}
+std::string AbstractSwitchCompiler::endcl() const {
+    return string("\n") + indent();
+}

src/SwitchStatement.hpp

@@ -0,0 +1,46 @@
+/** Contains an abstract switch statement, which can be turned to C code later
+ * on. */
+
+#pragma once
+
+#include <string>
+#include <vector>
+#include <ostream>
+#include <memory>
+
+struct SwitchStatement {
+    struct SwitchCaseContent {
+        std::string code;
+
+        bool operator==(const SwitchCaseContent& oth) const {
+            return code == oth.code;
+        }
+        bool operator<(const SwitchCaseContent& oth) const {
+            return code < oth.code;
+        }
+    };
+    struct SwitchCase {
+        uintptr_t low_bound, high_bound;
+        SwitchCaseContent content;
+    };
+
+    std::string switch_var;
+    std::string default_case;
+    std::vector<SwitchCase> cases;
+};
+
+class AbstractSwitchCompiler {
+    public:
+        AbstractSwitchCompiler(int indent=0);
+        void operator()(std::ostream& os, const SwitchStatement& sw);
+        std::string operator()(const SwitchStatement& sw);
+
+    protected:
+        virtual void to_stream(
+                std::ostream& os, const SwitchStatement& sw) = 0;
+        std::string indent_str(const std::string& str) ;
+        std::string indent() const;
+        std::string endcl() const;
+
+        int indent_count;
+};

src/main.cpp

@@ -7,6 +7,13 @@
 #include "SimpleDwarf.hpp"
 #include "DwarfReader.hpp"
 #include "CodeGenerator.hpp"
+#include "SwitchStatement.hpp"
+#include "NativeSwitchCompiler.hpp"
+#include "FactoredSwitchCompiler.hpp"
+#include "PcHoleFiller.hpp"
+#include "EmptyFdeDeleter.hpp"
+#include "ConseqEquivFilter.hpp"
+#include "OverriddenRowFilter.hpp"
 
 #include "settings.hpp"
 
@@ -56,6 +63,14 @@ MainOptions options_parse(int argc, char** argv) {
                 settings::pc_list = argv[option_pos];
             }
         }
+
+        else if(option == "--enable-deref-arg") {
+            settings::enable_deref_arg = true;
+        }
+
+        else if(option == "--keep-holes") {
+            settings::keep_holes = true;
+        }
     }
 
     if(!seen_switch_gen_policy) {
@@ -74,6 +89,8 @@ MainOptions options_parse(int argc, char** argv) {
         cerr << "Usage: "
              << argv[0]
              << " [--switch-per-func | --global-switch]"
+             << " [--enable-deref-arg]"
+             << " [--keep-holes]"
              << " [--pc-list PC_LIST_FILE] elf_path"
              << endl;
     }
@@ -87,15 +104,38 @@ int main(int argc, char** argv) {
     MainOptions opts = options_parse(argc, argv);
     SimpleDwarf parsed_dwarf = DwarfReader(opts.elf_path).read();
 
+    SimpleDwarf filtered_dwarf =
+        PcHoleFiller(!settings::keep_holes)(
+        EmptyFdeDeleter()(
+        OverriddenRowFilter()(
+        ConseqEquivFilter()(
+            parsed_dwarf))));
+
+    FactoredSwitchCompiler* sw_compiler = new FactoredSwitchCompiler(1);
     CodeGenerator code_gen(
-            parsed_dwarf,
+            filtered_dwarf,
             cout,
             [](const SimpleDwarf::Fde& fde) {
                 std::ostringstream ss;
                 ss << "_fde_" << fde.beg_ip;
                 return ss.str();
-            });
+            },
+            //new NativeSwitchCompiler()
+            sw_compiler
+            );
+
     code_gen.generate();
 
+#ifdef STATS
+    cerr << "Factoring stats:\nRefers: "
+         << sw_compiler->get_stats().refer_count
+         << "\nGenerated: "
+         << sw_compiler->get_stats().generated_count
+         << "\nAvoided: "
+         << sw_compiler->get_stats().refer_count
+            - sw_compiler->get_stats().generated_count
+         << "\n";
+#endif
+
     return 0;
 }

src/plt_std_expr.hpp

@@ -0,0 +1,63 @@
+#pragma once
+
+#include <dwarfpp/expr.hpp>
+
+static const dwarf::encap::loc_expr REFERENCE_PLT_EXPR(
+        std::vector<dwarf::encap::expr_instr> {
+            {
+               {
+                   .lr_atom  = 0x77,
+                   .lr_number = 8,
+                   .lr_number2 = 0,
+                   .lr_offset = 0
+               },
+               {
+                   .lr_atom  = 0x80,
+                   .lr_number = 0,
+                   .lr_number2 = 0,
+                   .lr_offset = 2
+               },
+               {
+                   .lr_atom  = 0x3f,
+                   .lr_number = 15,
+                   .lr_number2 = 0,
+                   .lr_offset = 4
+               },
+               {
+                   .lr_atom  = 0x1a,
+                   .lr_number = 0,
+                   .lr_number2 = 0,
+                   .lr_offset = 5
+               },
+               {
+                   .lr_atom  = 0x3b,
+                   .lr_number = 11,
+                   .lr_number2 = 0,
+                   .lr_offset = 6
+               },
+               {
+                   .lr_atom  = 0x2a,
+                   .lr_number = 0,
+                   .lr_number2 = 0,
+                   .lr_offset = 7
+               },
+               {
+                   .lr_atom  = 0x33,
+                   .lr_number = 3,
+                   .lr_number2 = 0,
+                   .lr_offset = 8
+               },
+               {
+                   .lr_atom  = 0x24,
+                   .lr_number = 0,
+                   .lr_number2 = 0,
+                   .lr_offset = 9
+               },
+               {
+                   .lr_atom  = 0x22,
+                   .lr_number = 0,
+                   .lr_number2 = 0,
+                   .lr_offset = 10
+               }
+            }
+            });

src/settings.cpp

@@ -3,4 +3,6 @@
 namespace settings {
     SwitchGenerationPolicy switch_generation_policy = SGP_SwitchPerFunc;
     std::string pc_list = "";
+    bool enable_deref_arg = false;
+    bool keep_holes = false;
 }

src/settings.hpp

@@ -15,4 +15,7 @@ namespace settings {
 
     extern SwitchGenerationPolicy switch_generation_policy;
     extern std::string pc_list;
+    extern bool enable_deref_arg;
+    extern bool keep_holes; /**< Keep holes between FDEs. Larger eh_elf files,
+                              but more accurate unwinding. */
 }

stack_walker/stack_walker.cpp

@@ -228,6 +228,9 @@ bool unwind_context(unwind_context_t& ctx) {
     uintptr_t tr_pc = ctx.rip - mmap_entry->beg;
     ctx = fde_func(ctx, tr_pc);
 
+    if(ctx.rip + 1 == 0 && ctx.rsp + 1 == 0 && ctx.rbp + 1 == 0) // no entry
+        return false;
+
     return true;
 }
 

stats/.gitignore

@@ -0,0 +1,3 @@
+venv
+elf_data*
+gathered

stats/README.md

@@ -0,0 +1,11 @@
+# Statistical scripts
+
+Computes stats about a whole lot of stuff.
+
+## Setup
+
+```sh
+  virtualenv -p python3 venv  # Do this only once
+  source venv/bin/activate  # Do this for every new shell working running the script
+  pip install -r requirements.txt  # Do this only once
+```

stats/fde_stats.py

@@ -0,0 +1,106 @@
+#!/usr/bin/env python3
+
+from stats_accu import StatsAccumulator
+import gather_stats
+
+import argparse
+import sys
+
+
+class Config:
+    def __init__(self):
+        args = self.parse_args()
+        self._cores = args.cores
+        self.feature = args.feature
+
+        if args.feature == 'gather':
+            self.output = args.output
+
+        elif args.feature == 'sample':
+            self.size = int(args.size)
+            self.output = args.output
+
+        elif args.feature == 'analyze':
+            self.data_file = args.data_file
+
+    @property
+    def cores(self):
+        if self._cores <= 0:
+            return None
+        return self._cores
+
+    def parse_args(self):
+        parser = argparse.ArgumentParser(
+            description="Gather statistics about system-related ELFs")
+
+        parser.add_argument('--cores', '-j', default=1, type=int,
+                            help=("Use N cores for processing. Defaults to "
+                                  "1. 0 to use up all cores."))
+
+        subparsers = parser.add_subparsers(help='Subcommands')
+
+        # Sample stats
+        parser_sample = subparsers.add_parser(
+            'sample',
+            help='Same as gather, but for a random subset of files')
+        parser_sample.set_defaults(feature='sample')
+        parser_sample.add_argument('--size', '-n',
+                                   default=1000,
+                                   help=('Pick this number of files'))
+        parser_sample.add_argument('--output', '-o',
+                                   default='elf_data',
+                                   help=('Output data to this file. Defaults '
+                                         'to "elf_data"'))
+
+        # Gather stats
+        parser_gather = subparsers.add_parser(
+            'gather',
+            help=('Gather system data into a file, to allow multiple '
+                  'analyses without re-scanning the whole system.'))
+        parser_gather.set_defaults(feature='gather')
+        parser_gather.add_argument('--output', '-o',
+                                   default='elf_data',
+                                   help=('Output data to this file. Defaults '
+                                         'to "elf_data"'))
+
+        # Analyze stats
+        parser_analyze = subparsers.add_parser(
+            'analyze',
+            help='Analyze data gathered by a previous run.')
+        parser_analyze.set_defaults(feature='analyze')
+        parser_analyze.add_argument('data_file',
+                                    default='elf_data',
+                                    help=('Analyze this data file. Defaults '
+                                          'to "elf_data".'))
+        # TODO histogram?
+
+        out = parser.parse_args()
+        if 'feature' not in out:
+            print("No subcommand specified.", file=sys.stderr)
+            parser.print_usage(file=sys.stderr)
+            sys.exit(1)
+
+        return out
+
+
+def main():
+    config = Config()
+
+    if config.feature == 'gather':
+        stats_accu = gather_stats.gather_system_files(config)
+        stats_accu.dump(config.output)
+
+    elif config.feature == 'sample':
+        stats_accu = gather_stats.gather_system_files(
+            config,
+            sample_size=config.size)
+        stats_accu.dump(config.output)
+
+    elif config.feature == 'analyze':
+        print("Not implemented", file=sys.stderr)
+        stats_accu = StatsAccumulator.load(config.data_file)
+        sys.exit(1)
+
+
+if __name__ == '__main__':
+    main()

stats/gather_stats.py

@@ -0,0 +1,147 @@
+from elftools.common.exceptions import DWARFError
+from pyelftools_overlay import system_elfs, get_cfi
+from elftools.dwarf import callframe
+import concurrent.futures
+import random
+
+
+from stats_accu import \
+    StatsAccumulator, SingleFdeData, FdeData, DwarfInstr
+
+
+class ProcessWrapper:
+    def __init__(self, fct):
+        self._fct = fct
+
+    def __call__(self, elf_descr):
+        try:
+            path, elftype = elf_descr
+
+            print("Processing {}…".format(path))
+
+            cfi = get_cfi(path)
+            if not cfi:
+                return None
+
+            return self._fct(path, elftype, cfi)
+        except DWARFError:
+            return None
+
+
+def process_wrapper(fct):
+    return ProcessWrapper(fct)
+
+
+@process_wrapper
+def process_elf(path, elftype, cfi):
+    ''' Process a single file '''
+
+    data = FdeData()
+
+    for entry in cfi:
+        if isinstance(entry, callframe.CIE):  # Is a CIE
+            process_cie(entry, data)
+        elif isinstance(entry, callframe.FDE):  # Is a FDE
+            process_fde(entry, data)
+
+    return SingleFdeData(path, elftype, data)
+
+
+def incr_cell(table, key):
+    ''' Increments table[key], or sets it to 1 if unset '''
+    if key in table:
+        table[key] += 1
+    else:
+        table[key] = 1
+
+
+def process_cie(cie, data):
+    ''' Process a CIE '''
+    pass  # Nothing needed from a CIE
+
+
+def process_fde(fde, data):
+    ''' Process a FDE '''
+    data.fde_count += 1
+
+    decoded = fde.get_decoded()
+    row_count = len(decoded.table)
+    incr_cell(data.fde_with_lines, row_count)
+
+    for row in decoded.table:
+        process_reg(data.regs.cfa, row['cfa'])
+        for entry in row:
+            if isinstance(entry, int):
+                process_reg(data.regs.regs[entry], row[entry])
+
+
+def process_reg(out_reg, reg_def):
+    ''' Process a register '''
+    if isinstance(reg_def, callframe.CFARule):
+        if reg_def.reg is not None:
+            out_reg.regs[reg_def.reg] += 1
+        else:
+            pass  # TODO exprs
+    else:
+        incr_cell(out_reg.instrs, DwarfInstr.of_pyelf(reg_def.type))
+        if reg_def.type == callframe.RegisterRule.REGISTER:
+            out_reg.regs[reg_def.arg] += 1
+        elif (reg_def.type == callframe.RegisterRule.EXPRESSION) \
+                or (reg_def.type == callframe.RegisterRule.VAL_EXPRESSION):
+            pass  # TODO exprs
+
+
+def gather_system_files(config, sample_size=None):
+    stats_accu = StatsAccumulator()
+
+    elf_list = []
+    for elf_path in system_elfs():
+        elf_list.append(elf_path)
+
+    if sample_size is not None:
+        elf_list_sampled = random.sample(elf_list, sample_size)
+        elf_list = elf_list_sampled
+
+    if config.cores > 1:
+        with concurrent.futures.ProcessPoolExecutor(max_workers=config.cores)\
+                as executor:
+            for fde in executor.map(process_elf, elf_list):
+                stats_accu.add_fde(fde)
+    else:
+        for elf in elf_list:
+            stats_accu.add_fde(process_elf(elf))
+
+    return stats_accu
+
+
+def map_system_files(mapper, sample_size=None, cores=None, include=None,
+                     elflist=None):
+    ''' `mapper` must take (path, elf_type, cfi) '''
+    if cores is None:
+        cores = 1
+    if include is None:
+        include = []
+
+    mapper = process_wrapper(mapper)
+
+    if elflist is None:
+        elf_list = []
+        for elf_path in system_elfs():
+            elf_list.append(elf_path)
+
+        if sample_size is not None:
+            elf_list_sampled = random.sample(elf_list, sample_size)
+            elf_list = elf_list_sampled
+
+        elf_list += list(map(lambda x: (x, None), include))
+    else:
+        elf_list = elflist
+
+    if cores > 1:
+        with concurrent.futures.ProcessPoolExecutor(max_workers=cores)\
+                as executor:
+            out = executor.map(mapper, elf_list)
+    else:
+        out = map(mapper, elf_list)
+
+    return out, elf_list

stats/helpers.py

@@ -0,0 +1,228 @@
+from elftools.dwarf import callframe
+import gather_stats
+import itertools
+import functools
+
+REGS_IDS = {
+    'RAX': 0,
+    'RDX': 1,
+    'RCX': 2,
+    'RBX': 3,
+    'RSI': 4,
+    'RDI': 5,
+    'RBP': 6,
+    'RSP': 7,
+    'R8':  8,
+    'R9':  9,
+    'R10': 10,
+    'R11': 11,
+    'R12': 12,
+    'R13': 13,
+    'R14': 14,
+    'R15': 15,
+    'RIP': 16
+}
+
+ID_TO_REG = [
+    'RAX',
+    'RDX',
+    'RCX',
+    'RBX',
+    'RSI',
+    'RDI',
+    'RBP',
+    'RSP',
+    'R8',
+    'R9',
+    'R10',
+    'R11',
+    'R12',
+    'R13',
+    'R14',
+    'R15',
+    'RIP',
+]
+
+HANDLED_REGS = list(map(lambda x: REGS_IDS[x], [
+    'RIP',
+    'RSP',
+    'RBP',
+    'RBX',
+]))
+
+ONLY_HANDLED_REGS = True  # only analyzed handled regs columns
+
+PLT_EXPR = [119, 8, 128, 0, 63, 26, 59, 42, 51, 36, 34]  # Handled exp
+
+
+def accumulate_regs(reg_list):
+    out = [0] * 17
+    for lst in reg_list:
+        for pos in range(len(lst)):
+            out[pos] += lst[pos]
+
+    return out
+
+
+def filter_none(lst):
+    for x in lst:
+        if x:
+            yield x
+
+
+def deco_filter_none(fct):
+    def wrap(lst):
+        return fct(filter_none(lst))
+    return wrap
+
+
+class FdeProcessor:
+    def __init__(self, fct, reducer=None):
+        self._fct = fct
+        self._reducer = reducer
+
+    def __call__(self, path, elftype, cfi):
+        out = []
+        for entry in cfi:
+            if isinstance(entry, callframe.FDE):
+                decoded = entry.get_decoded()
+                out.append(self._fct(path, entry, decoded))
+        if self._reducer is not None and len(out) >= 2:
+            out = [self._reducer(out)]
+        return out
+
+
+class FdeProcessorReduced:
+    def __init__(self, reducer):
+        self._reducer = reducer
+
+    def __call__(self, fct):
+        return FdeProcessor(fct, self._reducer)
+
+
+def fde_processor(fct):
+    return FdeProcessor(fct)
+
+
+def fde_processor_reduced(reducer):
+    return FdeProcessorReduced(reducer)
+
+
+def is_handled_expr(expr):
+    if expr == PLT_EXPR:
+        return True
+
+    if len(expr) == 2 and 0x70 <= expr[0] <= 0x89:
+        if expr[0] - 0x70 in HANDLED_REGS:
+            return True
+    return False
+
+
+# @fde_processor
+def find_non_cfa(path, fde, decoded):
+    regs_seen = 0
+    non_handled_regs = 0
+    non_handled_exp = 0
+    cfa_dat = [0, 0]  # Seen, expr
+    rule_type = {
+        callframe.RegisterRule.UNDEFINED: 0,
+        callframe.RegisterRule.SAME_VALUE: 0,
+        callframe.RegisterRule.OFFSET: 0,
+        callframe.RegisterRule.VAL_OFFSET: 0,
+        callframe.RegisterRule.REGISTER: 0,
+        callframe.RegisterRule.EXPRESSION: 0,
+        callframe.RegisterRule.VAL_EXPRESSION: 0,
+        callframe.RegisterRule.ARCHITECTURAL: 0,
+    }
+    problematic_paths = set()
+
+    for row in decoded.table:
+        for entry in row:
+            reg_def = row[entry]
+
+            if entry == 'cfa':
+                cfa_dat[0] += 1
+                if reg_def.expr:
+                    cfa_dat[1] += 1
+                    if not is_handled_expr(reg_def.expr):
+                        non_handled_exp += 1
+                        problematic_paths.add(path)
+                elif reg_def:
+                    if reg_def.reg not in HANDLED_REGS:
+                        non_handled_regs += 1
+                        problematic_paths.add(path)
+            if not isinstance(entry, int):  # CFA or PC
+                continue
+
+            if ONLY_HANDLED_REGS and entry not in HANDLED_REGS:
+                continue
+
+            rule_type[reg_def.type] += 1
+            reg_rule = reg_def.type
+
+            if reg_rule in [callframe.RegisterRule.OFFSET,
+                            callframe.RegisterRule.VAL_OFFSET]:
+                regs_seen += 1  # CFA
+            elif reg_rule == callframe.RegisterRule.REGISTER:
+                regs_seen += 1
+                if reg_def.arg not in HANDLED_REGS:
+                    problematic_paths.add(path)
+                    non_handled_regs += 1
+            elif reg_rule in [callframe.RegisterRule.EXPRESSION,
+                              callframe.RegisterRule.VAL_EXPRESSION]:
+                expr = reg_def.arg
+                if not is_handled_expr(reg_def.arg):
+                    problematic_paths.add(path)
+                    with open('/tmp/exprs', 'a') as handle:
+                        handle.write('[{} - {}] {}\n'.format(
+                            path, fde.offset,
+                            ', '.join(map(lambda x: hex(x), expr))))
+                    non_handled_exp += 1
+
+    return (regs_seen, non_handled_regs, non_handled_exp, rule_type, cfa_dat,
+            problematic_paths)
+
+
+def reduce_non_cfa(lst):
+    def merge_dict(d1, d2):
+        for x in d1:
+            d1[x] += d2[x]
+        return d1
+
+    def merge_list(l1, l2):
+        out = []
+        for pos in range(len(l1)):  # Implicit assumption len(l1) == len(l2)
+            out.append(l1[pos] + l2[pos])
+        return out
+
+    def merge_elts(accu, elt):
+        accu_regs, accu_nh, accu_exp, accu_rt, accu_cfa, accu_paths = accu
+        elt_regs, elt_nh, elt_exp, elt_rt, elt_cfa, elf_paths = elt
+        return (
+            accu_regs + elt_regs,
+            accu_nh + elt_nh,
+            accu_exp + elt_exp,
+            merge_dict(accu_rt, elt_rt),
+            merge_list(accu_cfa, elt_cfa),
+            accu_paths.union(elf_paths),
+        )
+
+    return functools.reduce(merge_elts, lst)
+
+
+@deco_filter_none
+def flatten_non_cfa(result):
+    flat = itertools.chain.from_iterable(result)
+    out = reduce_non_cfa(flat)
+    out_cfa = {
+        'seen': out[4][0],
+        'expr': out[4][1],
+        'offset': out[4][0] - out[4][1],
+    }
+    out = (out[0],
+           (out[1], out[0] + out_cfa['offset']),
+           (out[2], out[3]['EXPRESSION'] + out_cfa['expr']),
+           out[3],
+           out_cfa,
+           out[5])
+    return out

stats/pyelftools_overlay.py

@@ -0,0 +1,110 @@
+""" Overlay of PyElfTools for quick access to what we want here """
+
+from elftools.elf.elffile import ELFFile
+from elftools.common.exceptions import ELFError, DWARFError
+from stats_accu import ElfType
+import os
+
+
+ELF_BLACKLIST = [
+    '/usr/lib/libavcodec.so',
+]
+
+
+def get_cfi(path):
+    ''' Get the CFI entries from the ELF at the provided path '''
+
+    try:
+        with open(path, 'rb') as file_handle:
+            elf_file = ELFFile(file_handle)
+
+            if not elf_file.has_dwarf_info():
+                print("No DWARF")
+                return None
+
+            dw_info = elf_file.get_dwarf_info()
+            if dw_info.has_CFI():
+                cfis = dw_info.CFI_entries()
+            elif dw_info.has_EH_CFI():
+                cfis = dw_info.EH_CFI_entries()
+            else:
+                print("No CFI")
+                return None
+    except ELFError:
+        print("ELF Error")
+        return None
+    except DWARFError:
+        print("DWARF Error")
+        return None
+    except PermissionError:
+        print("Permission Error")
+        return None
+    except KeyError:
+        print("Key Error")
+        return None
+
+    return cfis
+
+
+def system_elfs():
+    ''' Iterator over system libraries '''
+
+    def readlink_rec(path):
+        if not os.path.islink(path):
+            return path
+
+        return readlink_rec(
+            os.path.join(os.path.dirname(path),
+                         os.readlink(path)))
+
+    sysbin_dirs = [
+        ('/lib', ElfType.ELF_LIB),
+        ('/usr/lib', ElfType.ELF_LIB),
+        ('/usr/local/lib', ElfType.ELF_LIB),
+        ('/bin', ElfType.ELF_BINARY),
+        ('/usr/bin', ElfType.ELF_BINARY),
+        ('/usr/local/bin', ElfType.ELF_BINARY),
+        ('/sbin', ElfType.ELF_BINARY),
+    ]
+    to_explore = sysbin_dirs
+
+    seen_elfs = set()
+
+    while to_explore:
+        bindir, elftype = to_explore.pop()
+
+        if not os.path.isdir(bindir):
+            continue
+
+        for direntry in os.scandir(bindir):
+            if not direntry.is_file():
+                if direntry.is_dir():
+                    to_explore.append((direntry.path, elftype))
+                continue
+
+            canonical_name = readlink_rec(direntry.path)
+            for blacked in ELF_BLACKLIST:
+                if canonical_name.startswith(blacked):
+                    continue
+            if canonical_name in seen_elfs:
+                continue
+
+            valid_elf = True
+            try:
+                with open(canonical_name, 'rb') as handle:
+                    magic_bytes = handle.read(4)
+                    if magic_bytes != b'\x7fELF':
+                        valid_elf = False
+                    elf_class = handle.read(1)
+                    if elf_class != b'\x02':  # ELF64
+                        valid_elf = False
+            except Exception:
+                continue
+            if not valid_elf:
+                continue
+
+            if not os.path.isfile(canonical_name):
+                continue
+
+            seen_elfs.add(canonical_name)
+            yield (canonical_name, elftype)

stats/requirements.txt

@@ -0,0 +1 @@
+git+https://github.com/eliben/pyelftools

stats/stats_accu.py

@@ -0,0 +1,263 @@
+from elftools.dwarf import callframe
+import enum
+import subprocess
+import re
+import json
+import collections
+
+from math import ceil
+
+
+class ProportionFinder:
+    ''' Finds figures such as median, etc. on the original structure of a
+    dictionnary mapping a value to its occurrence count '''
+
+    def __init__(self, count_per_value):
+        self.cumulative = []
+        prev_count = 0
+        for key in sorted(count_per_value.keys()):
+            n_count = prev_count + count_per_value[key]
+            self.cumulative.append(
+                (key, n_count))
+            prev_count = n_count
+
+        self.elem_count = prev_count
+
+    def find_at_proportion(self, proportion):
+        if not self.cumulative:  # Empty list
+            return None
+
+        low_bound = ceil(self.elem_count * proportion)
+
+        def binsearch(beg, end):
+            med = ceil((beg + end) / 2)
+
+            if beg + 1 == end:
+                return self.cumulative[beg][0]
+
+            if self.cumulative[med - 1][1] < low_bound:
+                return binsearch(med, end)
+            return binsearch(beg, med)
+
+        return binsearch(0, len(self.cumulative))
+
+
+def elf_so_deps(path):
+    ''' Get the list of shared objects dependencies of the given ELF object.
+    This is obtained by running `ldd`. '''
+
+    deps_list = []
+
+    try:
+        ldd_output = subprocess.check_output(['/usr/bin/ldd', path]) \
+            .decode('utf-8')
+        ldd_re = re.compile(r'^.* => (.*) \(0x[0-9a-fA-F]*\)$')
+
+        ldd_lines = ldd_output.strip().split('\n')
+        for line in ldd_lines:
+            line = line.strip()
+            match = ldd_re.match(line)
+            if match is None:
+                continue  # Just ignore that line — it might be eg. linux-vdso
+            deps_list.append(match.group(1))
+
+        return deps_list
+
+    except subprocess.CalledProcessError as exn:
+        raise Exception(
+            ("Cannot get dependencies for {}: ldd terminated with exit code "
+             "{}.").format(path, exn.returncode))
+
+
+class ElfType(enum.Enum):
+    ELF_LIB = enum.auto()
+    ELF_BINARY = enum.auto()
+
+
+class DwarfInstr(enum.Enum):
+    @staticmethod
+    def of_pyelf(val):
+        _table = {
+            callframe.RegisterRule.UNDEFINED: DwarfInstr.INSTR_UNDEF,
+            callframe.RegisterRule.SAME_VALUE: DwarfInstr.INSTR_SAME_VALUE,
+            callframe.RegisterRule.OFFSET: DwarfInstr.INSTR_OFFSET,
+            callframe.RegisterRule.VAL_OFFSET: DwarfInstr.INSTR_VAL_OFFSET,
+            callframe.RegisterRule.REGISTER: DwarfInstr.INSTR_REGISTER,
+            callframe.RegisterRule.EXPRESSION: DwarfInstr.INSTR_EXPRESSION,
+            callframe.RegisterRule.VAL_EXPRESSION:
+                DwarfInstr.INSTR_VAL_EXPRESSION,
+            callframe.RegisterRule.ARCHITECTURAL:
+                DwarfInstr.INSTR_ARCHITECTURAL,
+        }
+        return _table[val]
+
+    INSTR_UNDEF = enum.auto()
+    INSTR_SAME_VALUE = enum.auto()
+    INSTR_OFFSET = enum.auto()
+    INSTR_VAL_OFFSET = enum.auto()
+    INSTR_REGISTER = enum.auto()
+    INSTR_EXPRESSION = enum.auto()
+    INSTR_VAL_EXPRESSION = enum.auto()
+    INSTR_ARCHITECTURAL = enum.auto()
+
+
+def intify_dict(d):
+    out = {}
+    for key in d:
+        try:
+            nKey = int(key)
+        except Exception:
+            nKey = key
+
+        try:
+            out[nKey] = int(d[key])
+        except ValueError:
+            out[nKey] = d[key]
+    return out
+
+
+class RegData:
+    def __init__(self, instrs=None, regs=None, exprs=None):
+        if instrs is None:
+            instrs = {}
+        if regs is None:
+            regs = [0]*17
+        if exprs is None:
+            exprs = {}
+        self.instrs = intify_dict(instrs)
+        self.regs = regs
+        self.exprs = intify_dict(exprs)
+
+    @staticmethod
+    def map_dict_keys(fnc, dic):
+        out = {}
+        for key in dic:
+            out[fnc(key)] = dic[key]
+        return out
+
+    def dump(self):
+        return {
+            'instrs': RegData.map_dict_keys(lambda x: x.value, self.instrs),
+            'regs': self.regs,
+            'exprs': self.exprs,
+        }
+
+    @staticmethod
+    def load(data):
+        return RegData(
+            instrs=RegData.map_dict_keys(
+                lambda x: DwarfInstr(int(x)),
+                data['instrs']),
+            regs=data['regs'],
+            exprs=data['exprs'],
+        )
+
+
+class RegsList:
+    def __init__(self, cfa=None, regs=None):
+        if cfa is None:
+            cfa = RegsList.fresh_reg()
+        if regs is None:
+            regs = [RegsList.fresh_reg() for _ in range(17)]
+        self.cfa = cfa
+        self.regs = regs
+
+    @staticmethod
+    def fresh_reg():
+        return RegData()
+
+    def dump(self):
+        return {
+            'cfa': RegData.dump(self.cfa),
+            'regs': [RegData.dump(r) for r in self.regs],
+        }
+
+    @staticmethod
+    def load(data):
+        return RegsList(
+            cfa=RegData.load(data['cfa']),
+            regs=[RegData.load(r) for r in data['regs']],
+        )
+
+
+class FdeData:
+    def __init__(self, fde_count=0, fde_with_lines=None, regs=None):
+        if fde_with_lines is None:
+            fde_with_lines = {}
+        if regs is None:
+            regs = RegsList()
+
+        self.fde_count = fde_count
+        self.fde_with_lines = intify_dict(fde_with_lines)
+        self.regs = regs
+
+    def dump(self):
+        return {
+            'fde_count': self.fde_count,
+            'fde_with_lines': self.fde_with_lines,
+            'regs': self.regs.dump(),
+        }
+
+    @staticmethod
+    def load(data):
+        return FdeData(
+            fde_count=int(data['fde_count']),
+            fde_with_lines=data['fde_with_lines'],
+            regs=RegsList.load(data['regs']))
+
+
+class SingleFdeData:
+    def __init__(self, path, elf_type, data):
+        self.path = path
+        self.elf_type = elf_type
+        self.data = data  # < of type FdeData
+
+        self.gather_deps()
+
+    def gather_deps(self):
+        """ Collect ldd data on the binary """
+        # self.deps = elf_so_deps(self.path)
+        self.deps = []
+
+    def dump(self):
+        return {
+            'path': self.path,
+            'elf_type': self.elf_type.value,
+            'data': self.data.dump()
+        }
+
+    @staticmethod
+    def load(data):
+        return SingleFdeData(
+            data['path'],
+            ElfType(int(data['elf_type'])),
+            FdeData.load(data['data']))
+
+
+class StatsAccumulator:
+    def __init__(self):
+        self.fdes = []
+
+    def add_fde(self, fde_data):
+        if fde_data:
+            self.fdes.append(fde_data)
+
+    def get_fdes(self):
+        return self.fdes
+
+    def add_stats_accu(self, stats_accu):
+        for fde in stats_accu.get_fdes():
+            self.add_fde(fde)
+
+    def dump(self, path):
+        dict_form = [fde.dump() for fde in self.fdes]
+        with open(path, 'w') as handle:
+            handle.write(json.dumps(dict_form))
+
+    @staticmethod
+    def load(path):
+        with open(path, 'r') as handle:
+            text = handle.read()
+        out = StatsAccumulator()
+        out.fdes = [SingleFdeData.load(data) for data in json.loads(text)]
+        return out