Remove redundant calls of MaybeMountProcFS and refactor it.

It seems that we have lots of redundant MaybeMountProcFS, in particular
each mapped sanitized shared library calls it from AsanInitializer constructor.
Remove redudant MaybeMountProcFS calls from AsanInitializer and __asan_init.

Also, it seems that under qemu-aarch64 opening /proc/self/maps for reading
might be very expensive, so replace OpenFile("/proc/self/maps", RdOnly) with
FileExists("/proc/self/maps") in MaybeMountProcFS to avoid expensive calls.

Change-Id: I8ba28dbbc102be519fa2b284520509f601ec5cf7
Signed-off-by: Maxim Ostapenko <m.ostapenko@samsung.com>

diff --git a/libsanitizer/asan/asan_rtl.cc b/libsanitizer/asan/asan_rtl.cc
index 2b6287c..7f51016 100644 (file)
--- a/libsanitizer/asan/asan_rtl.cc
+++ b/libsanitizer/asan/asan_rtl.cc
@@ -410,11 +410,8 @@ static void MaybeDisableUlimit() {
 }
 
 bool MaybeMountProcFS() {
-  uptr tmp = OpenFile("/proc/self/maps", RdOnly);
-  if(!internal_iserror(tmp)) {
-    internal_close(tmp);
-    return true;
-  }
+  if (FileExists("/proc/self/maps")) return true;
+
   if(0 != mount("proc", "/proc", "proc", 0, 0)) {
     Report("Failed to mount /proc, Asan is likely to fail\n");
     return false;
@@ -591,7 +588,6 @@ void AsanInitFromRtl() {
 class AsanInitializer {
 public:  // NOLINT
   AsanInitializer() {
-    MaybeMountProcFS();
     AsanInitFromRtl();
   }
 };
@@ -645,7 +641,6 @@ void NOINLINE __asan_set_death_callback(void (*callback)(void)) {
 // Initialize as requested from instrumented application code.
 // We use this call as a trigger to wake up ASan from deactivated state.
 void __asan_init() {
-  MaybeMountProcFS();
   AsanActivate();
   AsanInitInternal();
 }