I tried to build libunwind for arm target and got a build error. Type
for "uc" argument is inconsistent between unw_init_local2 and
unw_init_local_common.
From 54fb6483e47916836c314a38715e8e0ce8c3da44 Mon Sep 17 00:00:00 2001
From: Guillaume Blanc <guillaume.blanc@parrot.com>
Date: Tue, 22 Aug 2017 16:46:20 +0200
Subject: [PATCH] arm: Fix unw_init_local2 argument type
If Thumb is used, the least bit of the retrived IP value is set,
which makes the retrived opcode based on the IP invalid.
This patch fixes such behavior and adds a missed condition
found with glibc built for recent ARMv7l with Thumb2.
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
CC: Yvan Roux
CC: Arun Sharma
CC: David Mosberger
Let's not drop error code or zero-return unconditionally.
This has been incurring occasional indefinite loop in
dotnet core when it already had hit the bottom by
continously returning 1 from unw_step();
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Rather than using a copy of dwarf_find_proc_info that differs from it slightly.
By using dwarf_find_proc_info, a potential search of the di table is
allowed, where it is omitted now. Also, for ARM, avoid runtime
checks about which kind of unwind table search to use after dl_iterate_phdr.
A couple of Debug() warnings about ip lookup failure are lost here.
The dwarf callback struct defintion is moved to Gfind_proc_info-lsb.c,
which becomes the only source file that needs it.
unw_is_signal_frame() returns <= 0 if not a signal frame. Several places in
code were only checking for a "if (unw_is_signal_frame())", or
"if (!unw_is_signal_frame())".
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
After successfully stepping the cursor on ARM, the proc info is
invalidated only in dwarf_step(). Invalidate the proc info also when
stepping with the non-dwarf based methods. This fixes
unw_get_proc_info() returning stale data.
The core dump unwinder can be used for demonstrating the bug. When
unwinding based only on DWARF data, the proc info is correct:
$ UNW_ARM_UNWIND_METHOD=1 ./test-coredump-unwind core `cat backing_files` 2>/dev/null
ip=0x000086d8 proc=000086d4-000086dc handler=0x00000000 lsda=0x00000000
ip=0x000086ef proc=000086dc-000086f2 handler=0x00000000 lsda=0x00000000
ip=0x000086e7 proc=000086dc-000086f2 handler=0x00000000 lsda=0x00000000
ip=0x00008597 proc=00008584-0000859a handler=0x00000000 lsda=0x00000000
ip=0x76e3ac3b proc=76e3aba0-76e3acec handler=0x00000000 lsda=0x00000000
When unwinding based only on the exidx method, we see the proc info
lagging behind:
$ UNW_ARM_UNWIND_METHOD=4 ./test-coredump-unwind core `cat backing_files` 2>/dev/null
ip=0x000086d8 proc=000086d4-000086db handler=0x00000000 lsda=0x00000000
ip=0x000086ef proc=000086d4-000086db handler=0x00000000 lsda=0x00000000
ip=0x000086e7 proc=000086dc-000086f3 handler=0x00000000 lsda=0x00000000
ip=0x00008597 proc=000086dc-000086f3 handler=0x00000000 lsda=0x00000000
ip=0x76e3ac3b proc=00008584-0000859b handler=0x00000000 lsda=0x00000000
ip=0x000085c3 proc=76e3aba0-76e3ae4b handler=0x00000000 lsda=0x00000000
Finally, with this patch applied, we get the desired proc info also with
the exidx unwinder:
$ UNW_ARM_UNWIND_METHOD=4 ./test-coredump-unwind core `cat backing_files` 2>/dev/null
ip=0x000086d8 proc=000086d4-000086db handler=0x00000000 lsda=0x00000000
ip=0x000086ef proc=000086dc-000086f3 handler=0x00000000 lsda=0x00000000
ip=0x000086e7 proc=000086dc-000086f3 handler=0x00000000 lsda=0x00000000
ip=0x00008597 proc=00008584-0000859b handler=0x00000000 lsda=0x00000000
ip=0x76e3ac3b proc=76e3aba0-76e3ae4b handler=0x00000000 lsda=0x00000000
ip=0x000085c3 proc=0000859c-00008613 handler=0x00000000 lsda=0x00000000
When cross-compiling libunwind with optimizations (-O1 or higher),
gcc-4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) optimizes away the memory
writes prior to the inline asm() statement in arm_local_resume() in the
non-signal-frame path, causing the `regs' array to be only allocated on
the stack, but not populated. This means that we are restoring garbage
to the registers.
As suggested in the GCC docs, add a fixed size input memory constraint
for the array content. This is enough to get the desired code to be
generated.
Adding __builtin_unreachable() to the point that we should never reach
was also in itself enough to inhibit the optimization. It also reduces
the function size by a few instructions.
Check the endianness earlier in unw_create_addr_space() on all
architectures to avoid leaking the dynamically allocated address space
struct.
This was already fixed for ARM in commit cf6a998796 ("Fix memory leak
in ARM unw_create_addr_space()"). Move the endianness check also on ARM
to avoid malloc() & free() in the error case.
The ARM EABI does not use the .eh_frame and .eh_frame_hdr sections for unwinding. Therefore it doesn't make sense to call dwarf_step if CONFIG_DEBUG_FRAME is not defined.
Define unw_tdep_context rather than using ucontext_t in order to support
systems that lack ucontext.h. Note that POSIX.1-2008 removed getcontext,
makecontext and swapcontext from its specification.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
In case the user doesn't specify whether to unwind using the ARM specific
unwind tabler or DWARF info libunwind should prefer the latter. Since DWARF
expressions are more powerful than the ARM specific unwind tables
arm_find_proc_info is changed to check for DWARF first.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Prevents unw_step from trying to unwind the stack using the ARM specific
unwind tables in case the DWARF based unwinding was successful.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Initialize the return value with -1 in order prevent arm_find_proc_info from
returning zero. This could happen in case the environemtn variable
UNW_ARM_UNWIND_METHOD doesn't allow exidx and/or dwarf unwinding.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
Change _UPTi_find_unwind_table to also look for the ARM specific unwind
information. Adjust the ARM unwind code to read memory using the accessor
routines.
Signed-off-by: Ken Werner <ken.werner@linaro.org>
