[sanitizers] Add init function to set alignment of low level allocator

ASan requires that the min alignment be at least the shadow
granularity, so add an init function to do that.

Differential Revision: https://reviews.llvm.org/D39473

llvm-svn: 318717

diff --git a/compiler-rt/lib/asan/asan_rtl.cc b/compiler-rt/lib/asan/asan_rtl.cc
index 27e4bd8..21fd0e2 100644 (file)
--- a/compiler-rt/lib/asan/asan_rtl.cc
+++ b/compiler-rt/lib/asan/asan_rtl.cc
@@ -407,6 +407,7 @@ static void AsanInitInternal() {
   MaybeReexec();
 
   // Setup internal allocator callback.
+  SetLowLevelAllocateMinAlignment(SHADOW_GRANULARITY);
   SetLowLevelAllocateCallback(OnLowLevelAllocate);
 
   InitializeAsanInterceptors();

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc b/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc
index 84f523c..fc4f7a7 100644 (file)
--- a/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_allocator.cc
@@ -178,11 +178,13 @@ void InternalFree(void *addr, InternalAllocatorCache *cache) {
 }
 
 // LowLevelAllocator
+constexpr uptr kLowLevelAllocatorDefaultAlignment = 8;
+static uptr low_level_alloc_min_alignment = kLowLevelAllocatorDefaultAlignment;
 static LowLevelAllocateCallback low_level_alloc_callback;
 
 void *LowLevelAllocator::Allocate(uptr size) {
   // Align allocation size.
-  size = RoundUpTo(size, 8);
+  size = RoundUpTo(size, low_level_alloc_min_alignment);
   if (allocated_end_ - allocated_current_ < (sptr)size) {
     uptr size_to_allocate = Max(size, GetPageSizeCached());
     allocated_current_ =
@@ -199,6 +201,11 @@ void *LowLevelAllocator::Allocate(uptr size) {
   return res;
 }
 
+void SetLowLevelAllocateMinAlignment(uptr alignment) {
+  CHECK(IsPowerOfTwo(alignment));
+  low_level_alloc_min_alignment = Max(alignment, low_level_alloc_min_alignment);
+}
+
 void SetLowLevelAllocateCallback(LowLevelAllocateCallback callback) {
   low_level_alloc_callback = callback;
 }

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
index 746ba22..92ea487 100644 (file)
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
@@ -206,6 +206,8 @@ class LowLevelAllocator {
   char *allocated_end_;
   char *allocated_current_;
 };
+// Set the min alignment of LowLevelAllocator to at least alignment.
+void SetLowLevelAllocateMinAlignment(uptr alignment);
 typedef void (*LowLevelAllocateCallback)(uptr ptr, uptr size);
 // Allows to register tool-specific callbacks for LowLevelAllocator.
 // Passing NULL removes the callback.