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Fix tdep_trace() returning bad count on aarch64.

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`tdep_trace()` did not return the right count value when it did not
complete successfully.

Also rewrote tests/Gtest-trace to (a) add more tests of
`unw_backtrace2()`, (2) give more meaningful verbose output for the poor
humans trying to figure out why it's failing, and (iii) iterate the
signal callback several times to detect cache-related edge cases.
This commit is contained in:
Stephen Webb
2024-07-17 12:22:19 -04:00
committed by Stephen M. Webb
parent 3c47821d68
commit 7aadfa552f
4 changed files with 212 additions and 143 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
.github/workflows/CI-unix.yml vendored
View File

@@ -50,7 +50,7 @@ jobs:
autoreconf -i
mkdir build
cd build
../configure --build=x86_64-pc-linux-gnu --host=${{ matrix.target.triple }}
../configure --build=x86_64-pc-linux-gnu --host=${{ matrix.target.triple }} --enable-debug
env:
CC: ${{ matrix.toolchain.CC }}
CXX: ${{ matrix.toolchain.CXX }}
@@ -74,6 +74,8 @@ jobs:
sudo bash -c 'echo core.%p.%p > /proc/sys/kernel/core_pattern'
ulimit -c unlimited
make -C build check -j8
env:
UNW_DEBUG_LEVEL: 4
- name: Show Logs
if: ${{ failure() }}

6
src/aarch64/Gtrace.c
View File

@@ -505,6 +505,8 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
else
{
/* Cached frame has no LR and neither do we. */
Debug (1, "returning -UNW_ESTOPUNWIND, depth %d\n", depth);
*size = depth;
return -UNW_ESTOPUNWIND;
}
if (likely(ret >= 0) && likely(f->fp_cfa_offset != -1))
@@ -542,6 +544,8 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
/* We cannot trace through this frame, give up and tell the
caller we had to stop. Data collected so far may still be
useful to the caller, so let it know how far we got. */
Debug (1, "returning -UNW_ESTOPUNWIND, depth %d\n", depth);
*size = depth;
ret = -UNW_ESTOPUNWIND;
break;
}
@@ -557,9 +561,7 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
buffer[depth++] = (void *) (pc - d->use_prev_instr);
}
#if UNW_DEBUG
Debug (1, "returning %d, depth %d\n", ret, depth);
#endif
*size = depth;
return ret;
}

5
src/x86_64/Gtrace.c
View File

@@ -538,7 +538,10 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
/* We cannot trace through this frame, give up and tell the
caller we had to stop. Data collected so far may still be
useful to the caller, so let it know how far we got. */
Debug (1, "returning UNW_ESTOPUNWIND, depth %d\n", depth);
*size = depth;
ret = -UNW_ESTOPUNWIND;
return ret;
break;
}
@@ -553,9 +556,7 @@ tdep_trace (unw_cursor_t *cursor, void **buffer, int *size)
buffer[depth++] = (void *) rip;
}
#if UNW_DEBUG
Debug (1, "returning %d, depth %d\n", ret, depth);
#endif
*size = depth;
return ret;
}

340
tests/Gtest-trace.c
View File

@@ -1,24 +1,33 @@
/* libunwind - a platform-independent unwind library
Copyright (C) 2010, 2011 by FERMI NATIONAL ACCELERATOR LABORATORY
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**
* @file tests/Gtest-trace.c
*
* Exercise the unw_backtrace*() functions and ensire they produce expected
* results.
*/
/*
* Copyright (C) 2010, 2011 by FERMI NATIONAL ACCELERATOR LABORATORY
* Copyright 2024 Stephen M. Webb <stephen.webb@bregmasoft.ca>
*
* This file is part of libunwind.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
@@ -47,156 +56,204 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#define SIG_STACK_SIZE 0x100000
int verbose;
int num_errors;
int verbose; /**< enable verbose mode? */
int repeat_count = 9; /**< number of times to exercise the signal handler */
int num_errors = 0; /**< cumulatiove error count */
/* These variables are global because they
* cause the signal stack to overflow */
char buf[512], name[256];
void *addresses[3][128];
* can cause the signal stack to overflow */
enum test_id {
TEST_UNW_STEP,
TEST_BACKTRACE,
TEST_UNW_BACKTRACE,
TEST_UNW_BACKTRACE2
};
enum { MAX_BACKTRACE_SIZE = 128 };
struct {
char const *name;
void *addresses[MAX_BACKTRACE_SIZE];
} trace[] = {
{ "unw_step" },
{ "backtrace" },
{ "unw_backtrace" },
{ "unw_backtrace2" }
};
unw_cursor_t cursor;
unw_context_t uc;
/**
* Dump a backtrace (in verbose mode).
*/
static void
dump_backtrace(int bt_count, enum test_id id)
{
if (verbose)
{
printf ("\t%s() [depth is %d]:\n", trace[id].name, bt_count);
for (int i = 0; i < bt_count; ++i)
printf ("\t #%-3d ip=%p\n", i, trace[id].addresses[i]);
}
}
/**
* Compare a backtrace from a backtrace call with a backtrace from unw_step().
*/
static void
compare_backtraces(int step_count, int backtrace_count, enum test_id id)
{
if (step_count != backtrace_count)
{
printf ("FAILURE: unw_step() loop and %s() depths differ: %d vs. %d\n",
trace[id].name,
step_count,
backtrace_count);
++num_errors;
}
else
{
for (int i = 1; i < step_count; ++i)
{
if (labs (trace[TEST_UNW_STEP].addresses[i] - trace[id].addresses[i]) > 1)
{
printf ("FAILURE: unw_step() loop and %s() addresses differ at %d: %p vs. %p\n",
trace[id].name, i,
trace[TEST_UNW_STEP].addresses[i],
trace[id].addresses[i]);
++num_errors;
}
}
}
}
/**
* Exercises `unw_backtrace()`. Compares the result of a raw `unw_step()` loop
* with the result of calling the system-supplied `backtrace()` (if any) with the
* result of the `unw_backtrace()` call, which may have taken the "fast path"
* (using cached data).
*
* If there is no system-supplied `backtrace()` call its just an alias for
* `unw_backtrace()` so the result better match.
*
* Also exercises `unw_backtrace2()` using the same context, since the code
* differs from `unw_backtrace()`.
*/
static void
do_backtrace (void)
{
unw_word_t ip;
int ret = -UNW_ENOINFO;
int depth = 0;
int i, n, m;
int unw_step_depth = 0;
int backtrace_depth = 0;
int unw_backtrace_depth = 0;
if (verbose)
printf ("\tnormal trace:\n");
{
printf ("\nBacktrace with implicit context:\n");
}
unw_getcontext (&uc);
/**
* Perform a naked `unw_step()` loop on the current context and save the IPs.
*/
ret = unw_getcontext (&uc);
if (ret != 0)
panic ("unw_getcontext failed\n");
if (unw_init_local (&cursor, &uc) < 0)
panic ("unw_init_local failed!\n");
do
{
unw_get_reg (&cursor, UNW_REG_IP, &ip);
addresses[0][depth] = (void *) ip;
trace[TEST_UNW_STEP].addresses[unw_step_depth++] = (void *) ip;
}
while ((ret = unw_step (&cursor)) > 0 && ++depth < 128);
while ((ret = unw_step (&cursor)) > 0 && unw_step_depth < MAX_BACKTRACE_SIZE);
if (ret < 0)
{
unw_get_reg (&cursor, UNW_REG_IP, &ip);
printf ("FAILURE: unw_step() returned %d for ip=%#010lx\n", ret, (long) ip);
++num_errors;
}
dump_backtrace(unw_step_depth, TEST_UNW_STEP);
if (verbose)
for (i = 0; i < depth; ++i)
printf ("\t #%-3d ip=%p\n", i, addresses[0][i]);
/*
* Call the system-supplied `backtrace()` (maybe) and compare with the
* `unw_step()`results. They should be identical.
*/
backtrace_depth = backtrace (trace[TEST_BACKTRACE].addresses, MAX_BACKTRACE_SIZE);
dump_backtrace(backtrace_depth, TEST_BACKTRACE);
compare_backtraces(unw_step_depth, backtrace_depth, TEST_BACKTRACE);
if (verbose)
printf ("\n\tvia backtrace():\n");
/*
* Call `unw_backtrace()` and compare with the `unw_step()`results. They
* should be identical.
*/
unw_backtrace_depth = unw_backtrace (trace[TEST_UNW_BACKTRACE].addresses,
MAX_BACKTRACE_SIZE);
dump_backtrace(unw_backtrace_depth, TEST_UNW_BACKTRACE);
compare_backtraces(unw_step_depth, unw_backtrace_depth, TEST_UNW_BACKTRACE);
n = backtrace (addresses[1], 128);
if (verbose)
for (i = 0; i < n; ++i)
printf ("\t #%-3d ip=%p\n", i, addresses[1][i]);
if (verbose)
printf ("\n\tvia unw_backtrace():\n");
m = unw_backtrace (addresses[2], 128);
if (verbose)
for (i = 0; i < m; ++i)
printf ("\t #%-3d ip=%p\n", i, addresses[2][i]);
if (m != depth+1)
{
printf ("FAILURE: unw_step() loop and unw_backtrace() depths differ: %d vs. %d\n", depth, m);
++num_errors;
}
if (n != depth+1)
{
printf ("FAILURE: unw_step() loop and backtrace() depths differ: %d vs. %d\n", depth, n);
++num_errors;
}
if (n == m)
for (i = 1; i < n; ++i)
/* Allow one in difference in comparison, trace returns adjusted addresses. */
if (labs (addresses[1][i] - addresses[2][i]) > 1)
{
printf ("FAILURE: backtrace() and unw_backtrace() addresses differ at %d: %p vs. %p\n",
i, addresses[1][i], addresses[2][i]);
++num_errors;
}
if (n == depth+1)
for (i = 1; i < depth; ++i)
/* Allow one in difference in comparison, trace returns adjusted addresses. */
if (labs (addresses[0][i] - addresses[1][i]) > 1)
{
printf ("FAILURE: unw_step() loop and backtrace() addresses differ at %d: %p vs. %p\n",
i, addresses[0][i], addresses[1][i]);
++num_errors;
}
/*
* Call `unw_backtrace2()` on the current context and compare with the
* `unw_step()`results. They should be identical.
*/
int unw_backtrace2_depth = unw_backtrace2 (trace[TEST_UNW_BACKTRACE2].addresses,
MAX_BACKTRACE_SIZE,
&uc,
0);
dump_backtrace(unw_backtrace2_depth, TEST_UNW_BACKTRACE2);
compare_backtraces(unw_step_depth, unw_backtrace2_depth, TEST_UNW_BACKTRACE2);
}
/**
* Exercises `unw_backtrace2()` using the context passed in to a signal
* handler. Compares the result of a raw `unw_step()` loop with the result of
* the `unw_backtrace2()` call, which may have taken the "fast path" (using
* cached data).
*/
void
do_backtrace_with_context(void *context)
{
unw_word_t ip;
int ret = -UNW_ENOINFO;
int depth = 0;
int i, m;
int unw_step_depth = 0;
int unw_backtrace2_depth;
if (verbose)
printf ("\tnormal trace:\n");
{
printf ("\nbacktrace with explicit context:\n");
}
/**
* Perform a naked `unw_step()` loop on the passed context and save the IPs.
*/
if (unw_init_local2 (&cursor, (unw_context_t*)context, UNW_INIT_SIGNAL_FRAME) < 0)
panic ("unw_init_local2 failed!\n");
do
{
unw_get_reg (&cursor, UNW_REG_IP, &ip);
addresses[0][depth] = (void *) ip;
trace[TEST_UNW_STEP].addresses[unw_step_depth++] = (void *) ip;
}
while ((ret = unw_step (&cursor)) > 0 && ++depth < 128);
while ((ret = unw_step (&cursor)) > 0 && unw_step_depth < MAX_BACKTRACE_SIZE);
if (ret < 0)
{
unw_get_reg (&cursor, UNW_REG_IP, &ip);
printf ("FAILURE: unw_step() returned %d for ip=%#010lx\n", ret, (long) ip);
++num_errors;
}
dump_backtrace(unw_step_depth, TEST_UNW_STEP);
if (verbose)
for (i = 0; i < depth; ++i)
printf ("\t #%-3d ip=%p\n", i, addresses[0][i]);
if (verbose)
printf ("\n\tvia unw_backtrace2():\n");
m = unw_backtrace2 (addresses[1], 128, (unw_context_t*)context, UNW_INIT_SIGNAL_FRAME);
if (verbose)
for (i = 0; i < m; ++i)
printf ("\t #%-3d ip=%p\n", i, addresses[1][i]);
if (m != depth+1)
{
printf ("FAILURE: unw_step() loop and unw_backtrace2() depths differ: %d vs. %d\n", depth, m);
++num_errors;
}
if (m == depth + 1)
for (i = 0; i < depth; ++i)
/* Allow one in difference in comparison, trace returns adjusted addresses. */
if ( labs(addresses[0][i] - addresses[1][i]) > 1)
{
printf ("FAILURE: unw_step() loop and unw_backtrace2() addresses differ at %d: %p vs. %p\n",
i, addresses[0][i], addresses[1][i]);
++num_errors;
}
/*
* Call `unw_backtrace2()` on the passed context and compare with the
* `unw_step()`results. They should be identical.
*/
unw_backtrace2_depth = unw_backtrace2 (trace[TEST_UNW_BACKTRACE2].addresses,
MAX_BACKTRACE_SIZE,
(unw_context_t*)context,
UNW_INIT_SIGNAL_FRAME);
dump_backtrace(unw_backtrace2_depth, TEST_UNW_BACKTRACE2);
compare_backtraces(unw_step_depth, unw_backtrace2_depth, TEST_UNW_BACKTRACE2);
}
void
@@ -239,48 +296,47 @@ bar (long v)
void
sighandler (int signal, siginfo_t *siginfo UNUSED, void *context)
{
ucontext_t *uc UNUSED;
int sp;
uc = context;
if (verbose)
{
int sp;
ucontext_t *ctxt UNUSED = context;
printf ("sighandler: got signal %d, sp=%p", signal, (void *)&sp);
#if UNW_TARGET_IA64
# if defined(__linux__)
printf (" @ %#010lx", uc->uc_mcontext.sc_ip);
printf (" @ %#010lx", ctxt->uc_mcontext.sc_ip);
# else
{
uint16_t reason;
uint64_t ip;
uint16_t reason;
uint64_t ip;
__uc_get_reason (uc, &reason);
__uc_get_ip (uc, &ip);
printf (" @ %#010lx (reason=%d)", ip, reason);
__uc_get_reason (ctxt, &reason);
__uc_get_ip (ctxt, &ip);
printf (" @ %#010lx (reason=%d)", ip, reason);
}
# endif
#elif UNW_TARGET_X86
#if defined __linux__
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.gregs[REG_EIP]);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.gregs[REG_EIP]);
#elif defined __FreeBSD__
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.mc_eip);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.mc_eip);
#endif
#elif UNW_TARGET_X86_64
#if defined __linux__ || defined __sun
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.gregs[REG_RIP]);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.gregs[REG_RIP]);
#elif defined __FreeBSD__
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.mc_rip);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.mc_rip);
#endif
#elif defined UNW_TARGET_ARM
#if defined __linux__
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.arm_pc);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.arm_pc);
#elif defined __FreeBSD__
printf (" @ %#010lx", (unsigned long) uc->uc_mcontext.__gregs[_REG_PC]);
printf (" @ %#010lx", (unsigned long) ctxt->uc_mcontext.__gregs[_REG_PC]);
#endif
#endif
printf ("\n");
}
do_backtrace();
do_backtrace_with_context(context);
}
@@ -306,9 +362,16 @@ main (int argc, char **argv UNUSED)
if (sigaction (SIGTERM, &act, NULL) < 0)
panic ("sigaction: %s\n", strerror (errno));
if (verbose)
printf ("\nBacktrace across signal handler:\n");
kill (getpid (), SIGTERM);
/*
* Repeatedly invoke the signal hander to make sure any global cache does not
* get corrupted.
*/
for (int i = 0; i < repeat_count; ++i)
{
if (verbose)
printf ("\nBacktrace across signal handler (iteration %d):\n", i+1);
kill (getpid (), SIGTERM);
}
#ifdef HAVE_SIGALTSTACK
if (verbose)
@@ -326,6 +389,7 @@ main (int argc, char **argv UNUSED)
act.sa_flags = SA_ONSTACK | SA_SIGINFO;
if (sigaction (SIGTERM, &act, NULL) < 0)
panic ("sigaction: %s\n", strerror (errno));
kill (getpid (), SIGTERM);
#endif /* HAVE_SIGALTSTACK */