[compiler-rt] [msan][aarch64] mallinfo interceptor (PR #73728)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Vitaly Buka (vitalybuka)

<details>
<summary>Changes</summary>

Not sure how the previous implementation supposed to work, but the test
was disabled.

This implementation works for x86_64 and aarch64.


---
Full diff: https://github.com/llvm/llvm-project/pull/73728.diff


2 Files Affected:

- (modified) compiler-rt/lib/msan/msan_interceptors.cpp (+15-12) 
- (modified) compiler-rt/test/msan/Linux/mallinfo.cpp (-1) 


``````````diff
diff --git a/compiler-rt/lib/msan/msan_interceptors.cpp b/compiler-rt/lib/msan/msan_interceptors.cpp
index bac756424e28ca7..dfecf6f7c470a6c 100644
--- a/compiler-rt/lib/msan/msan_interceptors.cpp
+++ b/compiler-rt/lib/msan/msan_interceptors.cpp
@@ -244,20 +244,23 @@ INTERCEPTOR(uptr, malloc_usable_size, void *ptr) {
 #endif
 
 #if !SANITIZER_FREEBSD && !SANITIZER_NETBSD
-// This function actually returns a struct by value, but we can't unpoison a
-// temporary! The following is equivalent on all supported platforms but
-// aarch64 (which uses a different register for sret value).  We have a test
-// to confirm that.
-INTERCEPTOR(void, mallinfo, __sanitizer_struct_mallinfo *sret) {
-#ifdef __aarch64__
-  uptr r8;
-  asm volatile("mov %0,x8" : "=r" (r8));
-  sret = reinterpret_cast<__sanitizer_struct_mallinfo*>(r8);
-#endif
-  REAL(memset)(sret, 0, sizeof(*sret));
+
+template <class T>
+static NOINLINE void clear_mallinfo(T *sret) {
+  ENSURE_MSAN_INITED();
+  internal_memset(sret, 0, sizeof(*sret));
   __msan_unpoison(sret, sizeof(*sret));
 }
-#define MSAN_MAYBE_INTERCEPT_MALLINFO INTERCEPT_FUNCTION(mallinfo)
+
+// Interceptor relies on NRVO and assumes that sret will be pre-allocated in
+// caller frame.
+INTERCEPTOR(__sanitizer_struct_mallinfo, mallinfo) {
+  __sanitizer_struct_mallinfo sret;
+  clear_mallinfo(&sret);
+  return sret;
+}
+
+#  define MSAN_MAYBE_INTERCEPT_MALLINFO INTERCEPT_FUNCTION(mallinfo)
 #else
 #define MSAN_MAYBE_INTERCEPT_MALLINFO
 #endif
diff --git a/compiler-rt/test/msan/Linux/mallinfo.cpp b/compiler-rt/test/msan/Linux/mallinfo.cpp
index b2021c5df3cec84..3c3692969852f9b 100644
--- a/compiler-rt/test/msan/Linux/mallinfo.cpp
+++ b/compiler-rt/test/msan/Linux/mallinfo.cpp
@@ -1,5 +1,4 @@
 // RUN: %clangxx_msan -O0 -g %s -o %t && %run %t
-// UNSUPPORTED: aarch64-target-arch
 
 #include <assert.h>
 #include <malloc.h>

``````````

</details>


https://github.com/llvm/llvm-project/pull/73728