[llvm-branch-commits] [compiler-rt] release/19.x: [sanitizer_common] Don't use syscall(SYS_clone) on Linux/sparc64 (#100534) (PR #101137)

[Tobias Hieta via llvm-branch-commits]

https://github.com/tru updated https://github.com/llvm/llvm-project/pull/101137

>From 708cb9cd3a4b7ca182e35a5b3c17f10f18215084 Mon Sep 17 00:00:00 2001
From: Rainer Orth <ro at gcc.gnu.org>
Date: Tue, 30 Jul 2024 08:57:25 +0200
Subject: [PATCH] [sanitizer_common] Don't use syscall(SYS_clone) on
 Linux/sparc64 (#100534)

```
  SanitizerCommon-Unit :: ./Sanitizer-sparc-Test/SanitizerCommon/StartSubprocessTest
```
and every single test using the `llvm-symbolizer` `FAIL` on
Linux/sparc64 in a very weird way: when using `StartSubprocess`, there's
a call to `internal_fork`, but we never reach `internal_execve`.
`internal_fork` is implemented using `syscall(SYS_clone)`. The calling
convention of that syscall already varies considerably between targets,
but as documented in `clone(2)`, SPARC again is widely different.
Instead of trying to match `glibc` here, this patch just calls `__fork`.

Tested on `sparc64-unknown-linux-gnu` and `x86_64-pc-linux-gnu`.

(cherry picked from commit 1c53b907bd6348138a59da270836fc9b4c161a07)
---
 compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
index 1d6a55bdb7f385..50e41da68d959a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -826,10 +826,16 @@ uptr internal_sigaltstack(const void *ss, void *oss) {
   return internal_syscall(SYSCALL(sigaltstack), (uptr)ss, (uptr)oss);
 }
 
+extern "C" pid_t __fork(void);
+
 int internal_fork() {
 #    if SANITIZER_LINUX
 #      if SANITIZER_S390
   return internal_syscall(SYSCALL(clone), 0, SIGCHLD);
+#      elif SANITIZER_SPARC
+  // The clone syscall interface on SPARC differs massively from the rest,
+  // so fall back to __fork.
+  return __fork();
 #      else
   return internal_syscall(SYSCALL(clone), SIGCHLD, 0);
 #      endif