[tsan] Reduce MapRodata frame size

arch64 triggers -Wframe-larger-than=530.

Author: vitalybuka

compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp

@@ -152,7 +152,7 @@ void WriteMemoryProfile(char *buf, uptr buf_size, u64 uptime_ns) {
 #if !SANITIZER_GO
 // Mark shadow for .rodata sections with the special Shadow::kRodata marker.
 // Accesses to .rodata can't race, so this saves time, memory and trace space.
-static void MapRodata() {
+static NOINLINE void MapRodata(char* buffer, uptr size) {
   // First create temp file.
   const char *tmpdir = GetEnv("TMPDIR");
   if (tmpdir == 0)
@@ -163,13 +163,12 @@ static void MapRodata() {
 #endif
   if (tmpdir == 0)
     return;
-  char name[256];
-  internal_snprintf(name, sizeof(name), "%s/tsan.rodata.%d",
+  internal_snprintf(buffer, size, "%s/tsan.rodata.%d",
                     tmpdir, (int)internal_getpid());
-  uptr openrv = internal_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
+  uptr openrv = internal_open(buffer, O_RDWR | O_CREAT | O_EXCL, 0600);
   if (internal_iserror(openrv))
     return;
-  internal_unlink(name);  // Unlink it now, so that we can reuse the buffer.
+  internal_unlink(buffer);  // Unlink it now, so that we can reuse the buffer.
   fd_t fd = openrv;
   // Fill the file with Shadow::kRodata.
   const uptr kMarkerSize = 512 * 1024 / sizeof(RawShadow);
@@ -188,8 +187,8 @@ static void MapRodata() {
   }
   // Map the file into shadow of .rodata sections.
   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
-  // Reusing the buffer 'name'.
-  MemoryMappedSegment segment(name, ARRAY_SIZE(name));
+  // Reusing the buffer 'buffer'.
+  MemoryMappedSegment segment(buffer, size);
   while (proc_maps.Next(&segment)) {
     if (segment.filename[0] != 0 && segment.filename[0] != '[' &&
         segment.IsReadable() && segment.IsExecutable() &&
@@ -209,7 +208,8 @@ static void MapRodata() {
 }
 
 void InitializeShadowMemoryPlatform() {
-  MapRodata();
+  char buffer[256];  // Keep in a different frame.
+  MapRodata(buffer, ARRAY_SIZE(buffer));
 }
 
 #endif  // #if !SANITIZER_GO