[sanitizer] Decorate /proc/self/maps better.

Summary:
Refactor the way /proc/self/maps entries are annotated to support most
(all?) posix platforms, with a special implementation for Android.
Extend the set of decorated Mmap* calls.

Replace shm_open with internal_open("/dev/shm/%s"). Shm_open is
problematic because it calls libc open() which may be intercepted.

Generic implementation has limits (max number of files under /dev/shm is
64K on my machine), which can be conceivably reached when sanitizing
multiple programs at once. Android implemenation is essentially free, and
enabled by default.

The test in sanitizer_common is copied to hwasan and not reused directly
because hwasan fails way too many common tests at the moment.

Reviewers: pcc, vitalybuka

Subscribers: srhines, kubamracek, jfb, llvm-commits, kcc

Differential Revision: https://reviews.llvm.org/D57720

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@353255 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 6 deletions

diff --git a/lib/hwasan/hwasan.cc b/lib/hwasan/hwasan.cc
index d28b1cc2a..9c83f73bd 100644
--- a/lib/hwasan/hwasan.cc
+++ b/lib/hwasan/hwasan.cc
@@ -190,17 +190,13 @@ static void HwasanFormatMemoryUsage(InternalScopedString &s) {
 #if SANITIZER_ANDROID
 static char *memory_usage_buffer = nullptr;
 
-#define PR_SET_VMA 0x53564d41
-#define PR_SET_VMA_ANON_NAME 0
-
 static void InitMemoryUsage() {
   memory_usage_buffer =
       (char *)MmapOrDie(kMemoryUsageBufferSize, "memory usage string");
   CHECK(memory_usage_buffer);
   memory_usage_buffer[0] = '\0';
-  CHECK(internal_prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME,
-                       (uptr)memory_usage_buffer, kMemoryUsageBufferSize,
-                       (uptr)memory_usage_buffer) == 0);
+  DecorateMapping((uptr)memory_usage_buffer, kMemoryUsageBufferSize,
+                  memory_usage_buffer);
 }
 
 void UpdateMemoryUsage() {