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Using libunwind for mac, since backtrace do not expect thread context… #1088

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Using libunwind for mac, since backtrace do not expect thread context… #1088

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c5f6535
Using libunwind for mac, since backtrace do not expect thread context…
saf-e Mar 28, 2024
03eec55
Merge branch 'getsentry:master' into pr/geting_context_for_mac
saf-e Nov 21, 2024
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110 changes: 110 additions & 0 deletions src/unwinder/sentry_unwinder_libbacktrace.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,115 @@
# define HAS_EXECINFO_H
#endif

#if defined(SENTRY_PLATFORM_MACOS) && defined(MAC_OS_X_VERSION_10_6)
# define HAS_LIBUNWIND
#endif

#ifdef HAS_EXECINFO_H
# include <execinfo.h>
#endif

#ifdef HAS_LIBUNWIND
# include <libunwind.h>

# define ARRAY_SIZE(a) sizeof(a) / sizeof(a[0])

static size_t
sentry__unwind_stack_libbacktrace_libnuwind(
const sentry_ucontext_t *uctx, void **ptrs, size_t max_frames)
{
unw_context_t ctx;
if (unw_getcontext(&ctx))
return 0;

unw_cursor_t cursor;
if (unw_init_local(&cursor, &ctx))
return 0;

# if defined(__x86_64__)
if (unw_set_reg(&cursor, UNW_X86_64_RAX,
uctx->user_context->uc_mcontext->__ss.__rax)
|| unw_set_reg(&cursor, UNW_X86_64_RDX,
uctx->user_context->uc_mcontext->__ss.__rdx)
|| unw_set_reg(&cursor, UNW_X86_64_RCX,
uctx->user_context->uc_mcontext->__ss.__rcx)
|| unw_set_reg(&cursor, UNW_X86_64_RBX,
uctx->user_context->uc_mcontext->__ss.__rbx)
|| unw_set_reg(&cursor, UNW_X86_64_RSI,
uctx->user_context->uc_mcontext->__ss.__rsi)
|| unw_set_reg(&cursor, UNW_X86_64_RDI,
uctx->user_context->uc_mcontext->__ss.__rdi)
|| unw_set_reg(&cursor, UNW_X86_64_RBP,
uctx->user_context->uc_mcontext->__ss.__rbp)
|| unw_set_reg(&cursor, UNW_X86_64_RSP,
uctx->user_context->uc_mcontext->__ss.__rsp)
|| unw_set_reg(
&cursor, UNW_X86_64_R8, uctx->user_context->uc_mcontext->__ss.__r8)
|| unw_set_reg(
&cursor, UNW_X86_64_R9, uctx->user_context->uc_mcontext->__ss.__r9)
|| unw_set_reg(&cursor, UNW_X86_64_R10,
uctx->user_context->uc_mcontext->__ss.__r10)
|| unw_set_reg(&cursor, UNW_X86_64_R11,
uctx->user_context->uc_mcontext->__ss.__r11)
|| unw_set_reg(&cursor, UNW_X86_64_R12,
uctx->user_context->uc_mcontext->__ss.__r12)
|| unw_set_reg(&cursor, UNW_X86_64_R13,
uctx->user_context->uc_mcontext->__ss.__r13)
|| unw_set_reg(&cursor, UNW_X86_64_R14,
uctx->user_context->uc_mcontext->__ss.__r14)
|| unw_set_reg(&cursor, UNW_X86_64_R15,
uctx->user_context->uc_mcontext->__ss.__r15)
|| unw_set_reg(
&cursor, UNW_REG_IP, uctx->user_context->uc_mcontext->__ss.__rip))
return 0;

# elif defined(__arm64__)
for (size_t i = 0;
i < ARRAY_SIZE(uctx->user_context->uc_mcontext->__ss.__x); ++i) {
if (unw_set_reg(&cursor, UNW_AARCH64_X0 + i,
uctx->user_context->uc_mcontext->__ss.__x[i])) {
return 0;
}
}

if (unw_set_reg(
&cursor, UNW_AARCH64_FP, uctx->user_context->uc_mcontext->__ss.__fp)
|| unw_set_reg(
&cursor, UNW_AARCH64_LR, uctx->user_context->uc_mcontext->__ss.__lr)
|| unw_set_reg(
&cursor, UNW_AARCH64_SP, uctx->user_context->uc_mcontext->__ss.__sp)
|| unw_set_reg(
&cursor, UNW_REG_IP, uctx->user_context->uc_mcontext->__ss.__pc))
return 0;

# endif

size_t n = 0;
for (int err = 1; err >= 0 && n < max_frames; err = unw_step(&cursor)) {
unw_word_t ip;
if (unw_get_reg(&cursor, UNW_REG_IP, &ip)) {
break;
}

# if defined(__arm64__)
// Strip pointer authentication, for some reason ptrauth_strip() not
// working
// https://developer.apple.com/documentation/security/preparing_your_app_to_work_with_pointer_authentication
ip &= 0x7fffffffffffull;
# endif

ptrs[n++] = (void *)ip;

// last frame
if (err == 0) {
break;
}
}

return n;
}
#endif

size_t
sentry__unwind_stack_libbacktrace(
void *addr, const sentry_ucontext_t *uctx, void **ptrs, size_t max_frames)
Expand All @@ -23,7 +128,12 @@ sentry__unwind_stack_libbacktrace(
#endif
return 0;
} else if (uctx) {
#ifdef HAS_LIBUNWIND
return sentry__unwind_stack_libbacktrace_libnuwind(
uctx, ptrs, max_frames);
#else
return 0;
#endif
}
#ifdef HAS_EXECINFO_H
return (size_t)backtrace(ptrs, (int)max_frames);
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