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[PATCH 9/X] [libsanitizer] Remove lazy thread initialisation

From: Matthew Malcomson <Matthew dot Malcomson at arm dot com>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Cc: nd <nd at arm dot com>, "kcc at google dot com" <kcc at google dot com>, "dvyukov at google dot com" <dvyukov at google dot com>, Martin Liska <mliska at suse dot cz>, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Kyrylo Tkachov <Kyrylo dot Tkachov at arm dot com>, "dodji at redhat dot com" <dodji at redhat dot com>, "jakub at redhat dot com" <jakub at redhat dot com>
Date: Tue, 5 Nov 2019 11:34:17 +0000
Subject: [PATCH 9/X] [libsanitizer] Remove lazy thread initialisation
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References: <157295142743.27946.1142544630216676787.scripted-patch-series@arm.com>

Backport from llvm upstream (monorepo revision 91167e2).
This was an experiment made possible by a non-standard feature of the
Android dynamic loader.

libsanitizer/ChangeLog:

2019-11-05  Matthew Malcomson  <matthew.malcomson@arm.com>

	* hwasan/hwasan_interceptors.cpp (HwasanThreadStartFunc):
	Re-introduce.
	(pthread_create): Use HwasanThreadStartFunc to initialise the
	sanitizer for each thread as it starts.
	* hwasan/hwasan_linux.cpp (GetCurrentThread): Assume thread is
	initialised.



###############     Attachment also inlined for ease of reply    ###############


diff --git a/libsanitizer/hwasan/hwasan_interceptors.cpp b/libsanitizer/hwasan/hwasan_interceptors.cpp
index 4f9bd3469eb10ca2cf3108326308e45e7a9d38b6..44e569ee6d721a99a3333a21ebf1a51fb33b6e7a 100644
--- a/libsanitizer/hwasan/hwasan_interceptors.cpp
+++ b/libsanitizer/hwasan/hwasan_interceptors.cpp
@@ -202,23 +202,33 @@ INTERCEPTOR_ALIAS(__sanitizer_struct_mallinfo, mallinfo);
 INTERCEPTOR_ALIAS(int, mallopt, int cmd, int value);
 INTERCEPTOR_ALIAS(void, malloc_stats, void);
 #endif
-#endif // HWASAN_WITH_INTERCEPTORS
 
+struct ThreadStartArg {
+  thread_callback_t callback;
+  void *param;
+};
+
+static void *HwasanThreadStartFunc(void *arg) {
+  __hwasan_thread_enter();
+  ThreadStartArg A = *reinterpret_cast<ThreadStartArg*>(arg);
+  UnmapOrDie(arg, GetPageSizeCached());
+  return A.callback(A.param);
+}
 
-#if HWASAN_WITH_INTERCEPTORS && !defined(__aarch64__)
-INTERCEPTOR(int, pthread_create, void *th, void *attr,
-            void *(*callback)(void *), void *param) {
+INTERCEPTOR(int, pthread_create, void *th, void *attr, void *(*callback)(void*),
+            void * param) {
   ScopedTaggingDisabler disabler;
+  ThreadStartArg *A = reinterpret_cast<ThreadStartArg *> (MmapOrDie(
+      GetPageSizeCached(), "pthread_create"));
+  *A = {callback, param};
   int res = REAL(pthread_create)(UntagPtr(th), UntagPtr(attr),
-                                 callback, param);
+                                 &HwasanThreadStartFunc, A);
   return res;
 }
-#endif
 
-#if HWASAN_WITH_INTERCEPTORS
 DEFINE_REAL(int, vfork)
 DECLARE_EXTERN_INTERCEPTOR_AND_WRAPPER(int, vfork)
-#endif
+#endif // HWASAN_WITH_INTERCEPTORS
 
 #if HWASAN_WITH_INTERCEPTORS && defined(__aarch64__)
 // Get and/or change the set of blocked signals.
@@ -331,9 +341,7 @@ void InitializeInterceptors() {
 #if defined(__linux__)
   INTERCEPT_FUNCTION(vfork);
 #endif  // __linux__
-#if !defined(__aarch64__)
   INTERCEPT_FUNCTION(pthread_create);
-#endif  // __aarch64__
 #endif
 
   inited = 1;
diff --git a/libsanitizer/hwasan/hwasan_linux.cpp b/libsanitizer/hwasan/hwasan_linux.cpp
index dfef11883a284dae0c96cfcc6a8fd1cc06c24d71..ed0f30161b023bf5927aa4a471f6a7c3edc8edf6 100644
--- a/libsanitizer/hwasan/hwasan_linux.cpp
+++ b/libsanitizer/hwasan/hwasan_linux.cpp
@@ -354,12 +354,7 @@ void AndroidTestTlsSlot() {}
 #endif
 
 Thread *GetCurrentThread() {
-  uptr *ThreadLong = GetCurrentThreadLongPtr();
-#if HWASAN_WITH_INTERCEPTORS
-  if (!*ThreadLong)
-    __hwasan_thread_enter();
-#endif
-  auto *R = (StackAllocationsRingBuffer *)ThreadLong;
+  auto *R = (StackAllocationsRingBuffer *)GetCurrentThreadLongPtr();
   return hwasanThreadList().GetThreadByBufferAddress((uptr)(R->Next()));
 }

Attachment: hwasan-patch09.patch
Description: hwasan-patch09.patch

References:
- [PATCH 0/X] Introduce HWASAN sanitizer to GCC
  - From: Matthew Malcomson

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