[llvm-commits] [compiler-rt] r172727 - in /compiler-rt/trunk/lib/asan: asan_interceptors.cc asan_internal.h asan_linux.cc asan_mac.cc asan_win.cc

[Alexey Samsonov]

Author: samsonov
Date: Thu Jan 17 09:45:28 2013
New Revision: 172727

URL: http://llvm.org/viewvc/llvm-project?rev=172727&view=rev
Log:
[ASan] minor changes to swapcontext handling: don't clear shadow memory if context stack is too large

Modified:
    compiler-rt/trunk/lib/asan/asan_interceptors.cc
    compiler-rt/trunk/lib/asan/asan_internal.h
    compiler-rt/trunk/lib/asan/asan_linux.cc
    compiler-rt/trunk/lib/asan/asan_mac.cc
    compiler-rt/trunk/lib/asan/asan_win.cc

Modified: compiler-rt/trunk/lib/asan/asan_interceptors.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_interceptors.cc?rev=172727&r1=172726&r2=172727&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_interceptors.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_interceptors.cc Thu Jan 17 09:45:28 2013
@@ -133,6 +133,18 @@
 #endif  // ASAN_INTERCEPT_SIGNAL_AND_SIGACTION
 
 #if ASAN_INTERCEPT_SWAPCONTEXT
+static void ClearShadowMemoryForContextStack(uptr stack, uptr ssize) {
+  // Align to page size.
+  uptr PageSize = GetPageSizeCached();
+  uptr bottom = stack & ~(PageSize - 1);
+  ssize += stack - bottom;
+  ssize = RoundUpTo(ssize, PageSize);
+  static const uptr kMaxSaneContextStackSize = 1 << 22;  // 4 Mb
+  if (ssize <= kMaxSaneContextStackSize) {
+    PoisonShadow(bottom, ssize, 0);
+  }
+}
+
 INTERCEPTOR(int, swapcontext, struct ucontext_t *oucp,
             struct ucontext_t *ucp) {
   static bool reported_warning = false;
@@ -143,16 +155,18 @@
   }
   // Clear shadow memory for new context (it may share stack
   // with current context).
-  ClearShadowMemoryForContext(ucp);
+  uptr stack, ssize;
+  ReadContextStack(ucp, &stack, &ssize);
+  ClearShadowMemoryForContextStack(stack, ssize);
   int res = REAL(swapcontext)(oucp, ucp);
   // swapcontext technically does not return, but program may swap context to
   // "oucp" later, that would look as if swapcontext() returned 0.
   // We need to clear shadow for ucp once again, as it may be in arbitrary
   // state.
-  ClearShadowMemoryForContext(ucp);
+  ClearShadowMemoryForContextStack(stack, ssize);
   return res;
 }
-#endif
+#endif  // ASAN_INTERCEPT_SWAPCONTEXT
 
 INTERCEPTOR(void, longjmp, void *env, int val) {
   __asan_handle_no_return();

Modified: compiler-rt/trunk/lib/asan/asan_internal.h
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_internal.h?rev=172727&r1=172726&r2=172727&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_internal.h (original)
+++ compiler-rt/trunk/lib/asan/asan_internal.h Thu Jan 17 09:45:28 2013
@@ -116,7 +116,7 @@
 void SetAlternateSignalStack();
 void UnsetAlternateSignalStack();
 void InstallSignalHandlers();
-void ClearShadowMemoryForContext(void *context);
+void ReadContextStack(void *context, uptr *stack, uptr *ssize);
 void AsanPlatformThreadInit();
 
 // Wrapper for TLS/TSD.

Modified: compiler-rt/trunk/lib/asan/asan_linux.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_linux.cc?rev=172727&r1=172726&r2=172727&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_linux.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_linux.cc Thu Jan 17 09:45:28 2013
@@ -120,20 +120,14 @@
 }
 
 #if !ASAN_ANDROID
-void ClearShadowMemoryForContext(void *context) {
+void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
   ucontext_t *ucp = (ucontext_t*)context;
-  uptr sp = (uptr)ucp->uc_stack.ss_sp;
-  uptr size = ucp->uc_stack.ss_size;
-  // Align to page size.
-  uptr PageSize = GetPageSizeCached();
-  uptr bottom = sp & ~(PageSize - 1);
-  size += sp - bottom;
-  size = RoundUpTo(size, PageSize);
-  PoisonShadow(bottom, size, 0);
+  *stack = (uptr)ucp->uc_stack.ss_sp;
+  *ssize = ucp->uc_stack.ss_size;
 }
 #else
-void ClearShadowMemoryForContext(void *context) {
-  UNIMPLEMENTED();
+void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
+  return UNIMPLEMENTED();
 }
 #endif
 

Modified: compiler-rt/trunk/lib/asan/asan_mac.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_mac.cc?rev=172727&r1=172726&r2=172727&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_mac.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_mac.cc Thu Jan 17 09:45:28 2013
@@ -153,7 +153,7 @@
   }
 }
 
-void ClearShadowMemoryForContext(void *context) {
+void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
   UNIMPLEMENTED();
 }
 

Modified: compiler-rt/trunk/lib/asan/asan_win.cc
URL: http://llvm.org/viewvc/llvm-project/compiler-rt/trunk/lib/asan/asan_win.cc?rev=172727&r1=172726&r2=172727&view=diff
==============================================================================
--- compiler-rt/trunk/lib/asan/asan_win.cc (original)
+++ compiler-rt/trunk/lib/asan/asan_win.cc Thu Jan 17 09:45:28 2013
@@ -102,7 +102,7 @@
   // Nothing here for now.
 }
 
-void ClearShadowMemoryForContext(void *context) {
+void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
   UNIMPLEMENTED();
 }