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stackwalk: fix heuristic termination #57801

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Merged
merged 1 commit into from
Mar 17, 2025
Merged

stackwalk: fix heuristic termination #57801

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10 changes: 7 additions & 3 deletions src/stackwalk.c
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Original file line number Diff line number Diff line change
Expand Up @@ -98,9 +98,13 @@ static int jl_unw_stepn(bt_cursor_t *cursor, jl_bt_element_t *bt_data, size_t *b
}
uintptr_t oldsp = thesp;
have_more_frames = jl_unw_step(cursor, from_signal_handler, &return_ip, &thesp);
if (oldsp >= thesp && !jl_running_under_rr(0)) {
// The stack pointer is clearly bad, as it must grow downwards.
if ((n < 2 ? oldsp > thesp : oldsp >= thesp) && !jl_running_under_rr(0)) {
// The stack pointer is clearly bad, as it must grow downwards,
// But sometimes the external unwinder doesn't check that.
// Except for n==0 when there is no oldsp and n==1 on all platforms but i686/x86_64.
// (on x86, the platform first pushes the new stack frame, then does the
// call, on almost all other platforms, the platform first does the call,
// then the user pushes the link register to the frame).
have_more_frames = 0;
}
if (return_ip == 0) {
Expand Down Expand Up @@ -132,11 +136,11 @@ static int jl_unw_stepn(bt_cursor_t *cursor, jl_bt_element_t *bt_data, size_t *b
// * The way that libunwind handles it in `unw_get_proc_name`:
// https://lists.nongnu.org/archive/html/libunwind-devel/2014-06/msg00025.html
uintptr_t call_ip = return_ip;
#if defined(_CPU_ARM_)
// ARM instruction pointer encoding uses the low bit as a flag for
// thumb mode, which must be cleared before further use. (Note not
// needed for ARM AArch64.) See
// https://github.com/libunwind/libunwind/pull/131
#ifdef _CPU_ARM_
call_ip &= ~(uintptr_t)0x1;
#endif
// Now there's two main cases to adjust for:
Expand Down