[llvm] 9337594 - [Support] Don't re-raise signals sent from kernel (#145759)

[via llvm-commits]

Author: Alex Langford
Date: 2025-07-09T14:53:15-07:00
New Revision: 9337594e3346e15b5bc90b5372b8b482aa5af37f

URL: https://github.com/llvm/llvm-project/commit/9337594e3346e15b5bc90b5372b8b482aa5af37f
DIFF: https://github.com/llvm/llvm-project/commit/9337594e3346e15b5bc90b5372b8b482aa5af37f.diff

LOG: [Support] Don't re-raise signals sent from kernel (#145759)

When an llvm tool crashes (e.g. from a segmentation fault),
SignalHandler will re-raise the signal. The effect is that crash reports
now contain SignalHandler in the stack trace. The crash reports are
still useful, but the presence of SignalHandler can confuse tooling and
automation that deduplicate or analyze crash reports.

rdar://150464802

Added: 
    

Modified: 
    llvm/lib/Support/Unix/Signals.inc

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/Unix/Signals.inc b/llvm/lib/Support/Unix/Signals.inc
index a4525a5903649..6cd38aabc734e 100644
--- a/llvm/lib/Support/Unix/Signals.inc
+++ b/llvm/lib/Support/Unix/Signals.inc
@@ -78,6 +78,10 @@
 #include <__le_cwi.h>
 #endif
 
+#if defined(__linux__)
+#include <sys/syscall.h>
+#endif
+
 using namespace llvm;
 
 static void SignalHandler(int Sig, siginfo_t *Info, void *);
@@ -413,10 +417,21 @@ static void SignalHandler(int Sig, siginfo_t *Info, void *) {
     raise(Sig);
 #endif
 
-  // Signal sent from another process, do not assume that continuing the
-  // execution would re-raise it.
-  if (Info->si_pid != getpid())
+#if defined(__linux__)
+  // Re-raising a signal via `raise` loses the original siginfo. Recent
+  // versions of linux (>= 3.9) support processes sending a signal to itself
+  // with arbitrary signal information using a syscall. If this syscall is
+  // unsupported, errno will be set to EPERM and `raise` will be used instead.
+  int retval =
+      syscall(SYS_rt_tgsigqueueinfo, getpid(), syscall(SYS_gettid), Sig, Info);
+  if (retval != 0 && errno == EPERM)
     raise(Sig);
+#else
+  // Signal sent from another userspace process, do not assume that continuing
+  // the execution would re-raise it.
+  if (Info->si_pid != getpid() && Info->si_pid != 0)
+    raise(Sig);
+#endif
 }
 
 static void InfoSignalHandler(int Sig) {