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[Unwind][AArch64] Match sigreturn instructions in big endian #167139

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[Unwind][AArch64] Match sigreturn instructions in big endian #167139

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[Unwind][AArch64] Match sigreturn instructions in big endian
hstk30-hw Nov 8, 2025
b6fed5b
Add comment about instruction sequence
hstk30-hw Nov 10, 2025
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17 changes: 16 additions & 1 deletion libunwind/src/UnwindCursor.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2803,6 +2803,21 @@ void UnwindCursor<A, R>::setInfoBasedOnIPRegister(bool isReturnAddress) {

#if defined(_LIBUNWIND_CHECK_LINUX_SIGRETURN) && \
defined(_LIBUNWIND_TARGET_AARCH64)

/*
* The linux sigreturn restorer stub will always have the form:
*
* d2801168 movz x8, #0x8b
* d4000001 svc #0x0
*/
#if defined(__AARCH64EB__)
#define MOVZ_X8_8B 0x681180d2
#define SVC_0 0x010000d4
#else
#define MOVZ_X8_8B 0xd2801168
#define SVC_0 0xd4000001
#endif

template <typename A, typename R>
bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
// Look for the sigreturn trampoline. The trampoline's body is two
Expand All @@ -2827,7 +2842,7 @@ bool UnwindCursor<A, R>::setInfoForSigReturn(Registers_arm64 &) {
return false;
auto *instructions = reinterpret_cast<const uint32_t *>(pc);
// Look for instructions: mov x8, #0x8b; svc #0x0
if (instructions[0] != 0xd2801168 || instructions[1] != 0xd4000001)
if (instructions[0] != MOVZ_X8_8B || instructions[1] != SVC_0)
return false;

_info = {};
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