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include %rip, %rsp, %rbp, and TSC_AUX in the fatal signal output #6

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Merged
ngbronson-openai merged 1 commit into from
Oct 29, 2025
Merged

include %rip, %rsp, %rbp, and TSC_AUX in the fatal signal output #6

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24 changes: 23 additions & 1 deletion folly/debugging/symbolizer/SignalHandler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -412,6 +412,27 @@ void dumpSignalInfo(int signum, siginfo_t* siginfo) {
print("), stack trace: ***\n");
}

void dumpContext(void* uctx) {
#if FOLLY_X64
print("*** Uctx (TSC_AUX ");
{
unsigned a, d, aux;
__asm__ volatile ("rdtscp" : "=a"(a), "=d"(d), "=c"(aux) :: "memory");
printHex(aux);
}

auto& gregs = static_cast<ucontext_t*>(uctx)->uc_mcontext.gregs;
print(") (RIP ");
printHex(gregs[REG_RIP]);
print(", RSP ");
printHex(gregs[REG_RSP]);
print(", RBP ");
printHex(gregs[REG_RBP]);
print(")\n");
flush();
#endif
}

// On Linux, pthread_t is a pointer, so 0 is an invalid value, which we
// take to indicate "no thread in the signal handler".
//
Expand All @@ -422,7 +443,7 @@ std::atomic<pthread_t> gSignalThread(kInvalidThreadId);
std::atomic<bool> gInRecursiveSignalHandler(false);

// Here be dragons.
void innerSignalHandler(int signum, siginfo_t* info, void* /* uctx */) {
void innerSignalHandler(int signum, siginfo_t* info, void* uctx) {
// First, let's only let one thread in here at a time.
pthread_t myId = pthread_self();

Expand Down Expand Up @@ -451,6 +472,7 @@ void innerSignalHandler(int signum, siginfo_t* info, void* /* uctx */) {
dumpTimeInfo();
dumpSignalInfo(signum, info);
gStackTracePrinter->printStackTrace(true); // with symbolization
dumpContext(uctx);

// Run user callbacks
auto callbacks = gFatalSignalCallbackRegistry.load(std::memory_order_acquire);
Expand Down
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