[scudo] Mitigate the overhead in cache storing when MTE enabled

mapSecondary() requires two mmap calls and may impact the performance in
some cases that use secondary allocator heavily. Only use
setMemoryPermission to reduce the time in contention of memory system calls.

Author: ChiaHungDuan

compiler-rt/lib/scudo/standalone/secondary.h

@@ -210,18 +210,10 @@ template <typename Config> class MapAllocatorCache {
     Entry.MemMap = H->MemMap;
     Entry.Time = Time;
     if (useMemoryTagging<Config>(Options)) {
-      if (Interval == 0 && !SCUDO_FUCHSIA) {
-        // Release the memory and make it inaccessible at the same time by
-        // creating a new MAP_NOACCESS mapping on top of the existing mapping.
-        // Fuchsia does not support replacing mappings by creating a new mapping
-        // on top so we just do the two syscalls there.
+      if (Interval == 0)
         Entry.Time = 0;
-        mapSecondary<Config>(Options, Entry.CommitBase, Entry.CommitSize,
-                             Entry.CommitBase, MAP_NOACCESS, Entry.MemMap);
-      } else {
-        Entry.MemMap.setMemoryPermission(Entry.CommitBase, Entry.CommitSize,
-                                         MAP_NOACCESS);
-      }
+      Entry.MemMap.setMemoryPermission(Entry.CommitBase, Entry.CommitSize,
+                                       MAP_NOACCESS);
     } else if (Interval == 0) {
       Entry.MemMap.releasePagesToOS(Entry.CommitBase, Entry.CommitSize);
       Entry.Time = 0;