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Author SHA1 Message Date
Arun Sharma
781d5d5263 One time whitespace fixup.
for f in $(find src include -name '*.[ch]'); do
  expand -t 8 $f > $tmp; mv $tmp $f;
done
2014-09-27 09:47:23 -07:00
Tim Deegan
4eb880e1b5 Implement DWARF DW_CFA_val_expression for x86_64
Ubuntu's libc-bin (2.15-0ubuntu20.2) on x86_64 uses DW_CFA_val_expression
in describing the pthread spinlock operations __lll_unlock_wake() and
__lll_lock_wait().  libunwind 1.1 doesn't understand that opcode and
so backtraces from those operations are truncated.

This changeset adds basic support for it, by adding a new type to
dwarf_loc_t that describes the register's actual contents rather than
its location.  I've only implemented the new type for x86_64, and
stubbed it out for all other architectures -- it looks like a lot
of that code is duplicated so oughtn't to be that hard, but I don't
have test cases for them.

Tested that DW_CFA_val_expression works on x86_64 (by using
https://code.google.com/p/gperftools/ on a lock-heavy program).
Build-tested on x86, x86_64 and arm.  The unit tests don't pass for me
on any of those archs, but this cset doesn't break anything that was
passing before.

Signed-off-by: Tim Deegan <tjd@phlegethon.org>
2014-02-08 20:19:20 -08:00
Ulrich Weigand
5710c98fbf Fix undefined behavior in dwarf_eval_expr
The dwarf_eval_expr routine uses macros push, pop, and pick to
manipulate the DWARF expression stack.  When these macros are
nested, e.g. in the implementation of DW_OP_dup:
          push (pick (0));
the combination can lead to unfortunate results.

In particular, when substituting into:
do {
  if (tos >= MAX_EXPR_STACK_SIZE)
    {
      Debug (1, "Stack overflow\n");
      return -UNW_EINVAL;
    }
  stack[tos++] = (x);
} while (0)
a value of "x" that makes use of "tos" (as instances of the
pick or pop macros do), the resulting expression will both
use and modify tos without an intervening sequence point,
which is undefined behavior according to the C standard.

And in fact with current GCC on PowerPC, this leads to a
miscompilation of the DW_OP_dup implementation.

This patch fixes the problem by assigning "x" to a
temporary variable before modifying tos.

Signed-off-by: Ulrich Weigand <uweigand@de.ibm.com>
2013-12-27 07:07:48 -08:00
Matt Fischer
3b8254d3b9 Fix unwind info freeing code in DWARF parser
The DWARF code allocates its unwind_info objects out of a
memory pool.  The code which frees the object therefore calls
the mempool freeing code.  However, there are cases where the
free code will be run with an unwind_info that was allocated
through a different mechanism (e.g. an ARM exidx table entry).
In these cases, the object should not be freed through the
mempool code.

To correct this, a check was added to ensure that the unwind_info
is of the appropriate type before passing the object along to the
mempool to be freed.
2013-05-19 00:10:18 -07:00
Matt Fischer
eac65dc9b8 Add basic support for the QNX operating system
This change adds some special cases to allow libunwind to compile
for QNX.

* QNX's copy of <elf.h> and <link.h> reside in sys/ instead.  To deal
  with this, an AC_CHECK_HEADERS() was added to check for the files
  in both locations.
* Similarly, QNX does not have <endian.h>.  In cases where the file is
  not found, logic was added to refer to QNX-specific macros to determine
  endianness.
* The QCC compiler, which is a wrapper around GCC, cannot handle some
  standard GCC options.  Therefore, logic was added to check for QCC,
  and when it is found, to suppress the use of -lgcc, and to express the
  option -nostartfiles as -Wc,-nostartfiles instead, which is correctly
  passed on to the underlying GCC.
* Finally, the support file os-qnx.c was added, patterned after the existing
  os-*.c files.  Only local image lookup is currently supported (see the
  comments for more information), but this is sufficient for QNX, since
  ptrace is not supported there anyway, and that is the only case where the
  function is required to do remote image lookup.

Change-Id: Ie7934f94a7317bdde59335f2acd4c3a97c0384c1
2013-05-13 10:50:17 -05:00
Arun Sharma
f92ecb6127 dwarf: Fix memory leak
Need to clean up by calling put_unwind_info() on code paths where fetch_proc_info() fails.

Signed-off-by: Arun Sharma <asharma@fb.com>
2013-04-02 21:19:56 -07:00
Chris January
679b65cd22 dwarf: Fix the order of the operands to the relational operators
dwarf_eval_expr are reversed compared with the DWARF spec.
2013-02-04 19:36:33 -08:00
Tommi Rantala
890e23eb9d Prefer NULL over zero 2012-09-28 14:51:21 +03:00
Tommi Rantala
22aff2cc1f Fix second operand read in dwarf_eval_expr()
Due to bad bracketing, the second operand was never read for dwarf
expressions that take two operands.

Caught with sparse.
2012-09-28 14:51:21 +03:00
Tommi Rantala
7d471b1440 Define and use `CONST_ATTR' 2012-09-28 14:51:21 +03:00
Tommi Rantala
088ac53775 Constify `operands' in src/dwarf/Gexpr.c 2012-09-28 14:50:03 +03:00
Tommi Rantala
a6f2a7a2a8 Fix incorrect .debug_frame lookup with non-zero text segment vaddr
Unwinding over ptrace and unwinding coredump fail to lookup the
.debug_frame dwarf data when the ELF file text segment virtual address
is non-zero. Looking at some binaries, the virtual address is non-zero
for non-pie binaries, and zero for PIC shared libraries and PIE
executables.

The core dump unwinder can be used for demonstrating the bug. Without
this patch, the unwinding fails badly (testing with a ARM qemu image):

 $ UNW_ARM_UNWIND_METHOD=1 ./test-coredump-unwind core `cat backing_files`
 test-coredump-unwind: unw_get_proc_info(ip=0x86d8) failed: ret=-10

After applying this patch, we can unwind all the way until running out
of dwarf data:

 $ UNW_ARM_UNWIND_METHOD=1 ./test-coredump-unwind core `cat backing_files`
     ip=0x000086d8 proc=000086d4-000086dc handler=0x00000000 lsda=0x00000000
 test-coredump-unwind: step
 test-coredump-unwind: step done:1
     ip=0x000086ef proc=000086dc-000086f2 handler=0x00000000 lsda=0x00000000
 test-coredump-unwind: step
 test-coredump-unwind: step done:1
     ip=0x000086e7 proc=000086dc-000086f2 handler=0x00000000 lsda=0x00000000
 test-coredump-unwind: step
 test-coredump-unwind: step done:1
     ip=0x00008597 proc=00008584-0000859a handler=0x00000000 lsda=0x00000000
 test-coredump-unwind: step
 test-coredump-unwind: step done:1
     ip=0x76eacc3b proc=76eacba0-76eaccec handler=0x00000000 lsda=0x00000000
 test-coredump-unwind: step
 test-coredump-unwind: step done:1
 test-coredump-unwind: unw_get_proc_info(ip=0x85c3) failed: ret=-10

Note how the binary itself is mapped to address 0x8000, the virtual
address for the text segment is 0x8000, and the .debug_frame program
counter values are relative to 0:

$ tr ' ' '\n' < backing_files
0x8000:/home/user/tests/crasher
0x76e96000:/lib/arm-linux-gnueabi/libc-2.13.so
0x76f77000:/lib/arm-linux-gnueabi/libgcc_s.so.1
0x76f88000:/lib/arm-linux-gnueabi/ld-2.13.so

$ readelf -l crasher
Elf file type is EXEC (Executable file)
Entry point 0x859d
There are 9 program headers, starting at offset 52

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  EXIDX          0x0007b0 0x000087b0 0x000087b0 0x00030 0x00030 R   0x4
  PHDR           0x000034 0x00008034 0x00008034 0x00120 0x00120 R E 0x4
  INTERP         0x000154 0x00008154 0x00008154 0x00013 0x00013 R   0x1
      [Requesting program interpreter: /lib/ld-linux.so.3]
  LOAD           0x000000 0x00008000 0x00008000 0x007e4 0x007e4 R E 0x8000
  LOAD           0x000efc 0x00010efc 0x00010efc 0x00148 0x00154 RW 0x8000
  DYNAMIC        0x000f08 0x00010f08 0x00010f08 0x000f8 0x000f8 RW  0x4
  NOTE           0x000168 0x00008168 0x00008168 0x00044 0x00044 R   0x4
  GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RW  0x4
  GNU_RELRO      0x000efc 0x00010efc 0x00010efc 0x00104 0x00104 R   0x1

$ readelf --debug-dump=frames crasher | grep FDE
00000010 00000024 00000000 FDE cie=00000000 pc=00008614..000086d4
00000038 0000000c 00000000 FDE cie=00000000 pc=000086d4..000086dc
00000048 00000014 00000000 FDE cie=00000000 pc=000086dc..000086f2
00000060 00000014 00000000 FDE cie=00000000 pc=00008584..0000859a
2012-09-04 14:58:38 +03:00
Tommi Rantala
f93e1e93be Avoid LLVM -Wunused-value warning in src/dwarf/Gexpr.c
src/dwarf/Gexpr.c:434:4: warning: expression result unused [-Wunused-value]
          pop ();
          ^~~~~~
src/dwarf/Gexpr.c:211:14: note: expanded from:
  stack[--tos];                                 \
  ~~~~~ ~~~~~^
2012-09-04 14:58:38 +03:00
Tommi Rantala
fce25d74c9 Eliminate one heap allocation in dwarf_find_debug_frame()
Allocate `tab' from stack in dwarf_find_debug_frame(), as it's only a
few members and we only need it locally in the function.
2012-09-04 14:58:37 +03:00
Tommi Rantala
90d7baea35 Remove free() NULL pointer checks in load_debug_frame() error path
Just pass potentially NULL pointers to free() in the error path in
load_debug_frame(). Saved 40 bytes of code in libunwind.so on ARM -O2
thumb build at the expense of slightly slower execution.
2012-09-04 14:58:24 +03:00
Tommi Rantala
e61c6f69c3 Fix function name duplication in Debug() output
Fix function name duplication in Debug() output that was caused by
manually prepending the debug message with the function name.
2012-08-21 23:04:07 +03:00
Tommi Rantala
0fecf13d10 Fix --enable-debug-frame build
dwarf/Gfind_unwind_table.c: In function '_Ux86_dwarf_find_unwind_table':
dwarf/Gfind_unwind_table.c:223:46: error: 'struct elf_dyn_info' has no member named 'edi'
2012-07-31 16:21:15 +03:00
Arun Sharma
fa5409387c Merge branch 'coredump2' of https://github.com/adsharma/libunwind
Conflicts:
	src/ptrace/_UPT_find_proc_info.c
2012-05-23 20:51:50 -07:00
Jiri Olsa
69e300e8f6 dwarf: Get correct return from expression evaluation
Currently the expression evaluation always succeeds,
and possible error is not propagated to the caller.

The ',' operator makes the condition always return 0.

Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: Paul Pluzhnikov <ppluzhnikov@google.com>
2012-04-16 07:13:54 -07:00
Arun Sharma
9507a9b501 ia64: move ia64 specific code out of dwarf
We still need to fixup the callers to pick dwarf_find_unwind_table
vs ia64_find_unwind_table in a target dependent way.
2012-03-29 11:35:26 -07:00
Arun Sharma
5e59e93d04 dwarf: introduce a valid bit for dwarf_reg_state_t
Without this, cache_match() returns true when (ip == 0).
2012-03-25 18:33:40 -07:00
Arun Sharma
d04dc94cc2 dwarf: ip == 0 should't terminate unwind 2012-03-25 18:10:10 -07:00
Arun Sharma
43e5ee28c0 Demote the debug level to reduce verbosity 2012-03-25 17:44:53 -07:00
Arun Sharma
6525714c27 Move some dwarf functionality from ptrace to dwarf
Move ptrace-independent code from src/ptrace/_UPT_find_proc_info.c
to src/dwarf/{G,L}find_unwind_table.c. Name this moved function
dwarf_find_unwind_table().

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
2012-03-12 20:06:37 -07:00
Arun Sharma
786882ff8c Remove unused variable segbase 2011-11-12 10:02:09 -08:00
Ken Werner
1e644990c9 Only declare the start/end variables in case CONFIG_DEBUG_FRAME is defined.
Prevents compiler warnings about unused variables.

Signed-off-by: Ken Werner <ken.werner@linaro.org>
2011-11-12 09:47:12 -08:00
Arun Sharma
d20df8b318 Fix up the breakage when host != target 2011-10-31 22:33:47 -07:00
Ken Werner
059676cb00 Prevent the use of struct dl_phdr_info outside of dl_iterate_phdr
Since the dl_iterate_phdr is required for local unwinding only the use of
struct dl_phdr_info can be eliminated in case libunwind gets compiled for
remote unwinding. This enhances libunwinds portability to targets that
don't provide any dl_iterate_phdr functionality.

Signed-off-by: Ken Werner <ken.werner@linaro.org>
2011-10-29 17:12:43 -07:00
Ken Werner
0fed502a81 UNW_REMOTE_ONLY fixes
Exclude <link.h> because it is only required for local unwinding when
iterating over the program headers.

Have the following DWARF related functions available in case of
UNW_REMOTE_ONLY because they are used by libunwind-ptrace:
  dwarf_find_debug_frame
  locate_debug_info
  find_binary_for_address
  load_debug_frame
  debug_frame_tab_new
  debug_frame_tab_append
  debug_frame_tab_shrink
  debug_frame_tab_compare

Signed-off-by: Ken Werner <ken.werner@linaro.org>
2011-10-29 17:12:43 -07:00
Ken Werner
545023c207 Rework the lookup of the ARM specific unwind info
Implement routines for finding the proc_info and searching the unwind table
for the ARM backend.

Signed-off-by: Ken Werner <ken.werner@linaro.org>
2011-08-15 20:12:54 +02:00
Ken Werner
0b9f591823 Make the dwarf dl_iterate_phdr callback available within libunwind.
Rename the dwarf dl_iterate_phdr callback routine and the callback_data
structure to dwarf_callback and dwarf_callback_data. Make it available
within libunwind by declaring the two at the dwarf.h header file.

Signed-off-by: Ken Werner <ken.werner@linaro.org>
2011-08-15 20:12:54 +02:00
Lassi Tuura
9e98f15e9a Fast back-trace for x86_64 for only collecting the call stack.
Adds new function to perform a pure stack walk without unwinding,
functionally similar to backtrace() but accelerated by an address
attribute cache the caller maintains across calls.
2011-03-24 22:33:17 -07:00
Arun Sharma
46e10c5abe Support .debug_frame based unwinding in _UPTi_find_unwind_table()
Signed-off-by: Andris Zeila <andris.zeila@accenture.com>
2010-05-26 19:25:41 -07:00
Arun Sharma
546463d1e7 Factor out and export dwarf_find_debug_frame() function
Signed-off-by: Andris Zeila <andris.zeila@accenture.com>
2010-05-26 19:21:30 -07:00
Arun Sharma
b115ab645a Ignore separate debug files which contain a .gnu_debuglink section.
Current implementation fails to find separate debug symbols when
.gnu_debuglink is set to the same name of the target ELF basename
(e.g. "libc.so.6" for /lib/libc.so.6). This patch fixes this by ignoring
separate debug files that contain a .gnu_debuglink section.

It also fixes a small typo in a related Debug() line.

Signed-off-by: Andris Zeila <andris.zeila@accenture.com>
2010-05-15 11:57:35 -07:00
Lassi Tuura
a9dce3c06e During the stack unwinding process, the return address points to
the instruction after the call for a normal frame. libunwind uses
IP-1 to lookup unwind information. However, this is not necessary for
interrupted frames such as signal frames (or interrupt frames) in
the kernel context.

This patch handles both cases correctly.

Based on work by Mark Wielaard <mwielaard@redhat.com>
2010-04-24 19:16:09 -07:00
Lassi Tuura
4c553ceb2c Identify end-of-stack by undefined return address location. 2010-04-24 17:18:31 -07:00
Lassi Tuura
dac2d001af Identify signal frames by augmentation attribute. 2010-04-24 17:18:26 -07:00
Lassi Tuura
250382c56d Use wider format when printing addresses in debug format. 2010-04-24 17:18:19 -07:00
Arun Sharma
7bd264e292 Fix up what looks like an unintentional semi colon.
Thanks to Lassi Tuura for noticing it.
2010-03-23 10:37:21 -07:00
Paul Pluzhnikov
9626d66019 Fix a race condition in dwarf unwinding.
Original code was accessing rs_cache memory without holding a lock
in some cases. If there was sufficient cache pressure, entry being
accessed may be overwritten by another thread, resulting in a data
race.

We now make a thread local copy of the data, before releasing the
lock. If we end up supporting UNW_CACHE_PER_THREAD properly
in the future, this memcpy should be unnecessary.
2009-11-24 15:18:48 -08:00
Paul Pluzhnikov
2648a77f04 Simplify control flow
Greetings,

Attached patch gets rid of additional unnecessary branch (rs_get_cache
can not return NULL unless caching_policy is UNW_CACHE_NONE), gets rid of
goto's, and makes apply_reg_state (major CPU consumer) execute with cache
lock not held (before the patch, apply_reg_state was called with lock held
for newly-inserted entries, but not for found-in-cache entries).

Tested on Linux/x86_64 with no regressions.

Thanks,
--
Paul Pluzhnikov
2009-11-20 12:04:13 -08:00
Paul Pluzhnikov
f958b9dc4f Get rid of some bogus checks.
Greetings,

Attached patch is rather on the obvious side:
- rs1 can't be NULL since it's assigned on previous line
- rs_new never returns NULL, and if it ever did, we'd crash on memcpy that
  preceeds the NULL check.

Tested on Linux/x86_64 with no regressions.

Thanks,
--
Paul Pluzhnikov
2009-11-20 11:40:05 -08:00
Arun Sharma
d7089547e2 Fix a warning message on i386
Without this, we may be accessing data beyond the array bounds.
2009-10-23 22:38:11 -07:00
Arun Sharma
491d576529 Fix compiler warnings on x86_64 2009-10-16 14:01:50 -07:00
Paul Pluzhnikov
b56375e76a Reduce stack use and apply CONFIG_DEBUG_FRAME to more code.
Currently, libunwind allocates several PATH_MAX entries on stack, while
trying to find a binary via /proc/.../maps.

However stack space may be at premium (especially when sigaltstack is used),
and PATH_MAX on Linux is 4096, while SIGSTKSZ is only 8192 on x86.

Attached patch eliminates multiple PATH_MAX stack allocations, and simplifies
code in maps_next, at the cost of being unable to do anything if we can't
mmap one page. It appears to me that under such low-memory conditions,
libunwind will fail shortly elsewhere anyway.

This patch also disables more of debug_frame-handling code when
CONFIG_DEBUG_FRAME is undefined.

Tested on Linux/x86_64 with and without CONFIG_DEBUG_FRAME, no regressions.
2009-10-07 12:51:03 -07:00
Paul Pluzhnikov
fc2934aade Make the remaining sigprocmask calls conditional on --enable-block-signals 2009-09-29 23:14:50 -07:00
Paul Pluzhnikov
839db77b7b Wait if there is contention on the cache
The behavior on wait vs abort unwind depends on the locking primitive
chosen by the user. This makes the API consistent and independent of
the locking primitive.
2009-09-25 09:38:55 -07:00
Paul Pluzhnikov
84d4150668 Allow caller to block signals.
Greetings,

We use libunwind just for stack traces (I suspect many others do as well).

The use pattern is:

GetStackTrace(void** result, int max_depth)
{
...
  unw_getcontext(&uc);
  unw_init_local(&cursor, &uc);

  while (n < max_depth) {
    if (unw_get_reg(&cursor, UNW_REG_IP, (unw_word_t *) &ip) < 0) {
      break;
    }
    result[n++] = ip;
    if (unw_step(&cursor) <= 0) {
      break;
    }
  }

Given this usage, it is quite convenient for us to block signals (or
prevent signal handlers from re-entering libunwind by other means) at the
"top level", which makes most of the sigprocmask calls performed by
libunwind itself unneccessary.

The second patch in this series adds a configure option which removes most
of the sigprocmask calls.

Attached patch is a preliminary for it -- consolidating all of the
"sigprocmask; mutex_lock;" sequences into lock_acquire and "mutex_unlock;
sigprocmask;" sequences into lock_release.

Thanks,
--
Paul Pluzhnikov

commit 402d15b123d54a7669db7cf17a76dd315094e472
Author: Paul Pluzhnikov <ppluzhnikov@google.com>
Date:   Mon Sep 21 10:18:28 2009 -0700

    Replace "sigprocmask + mutext_lock" with a single lock_acquire.
    Likewise, replace "mutext_unlock + sigprocmask" with lock_release.
2009-09-25 09:35:31 -07:00
Arun Sharma
9607c6407c Fixup CONFIG_DEBUG_FRAME support. 2009-03-17 19:08:58 -07:00