[asan] adaptive redzones for globals (the larger the global the larger is the redzone)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173335 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index f4715f541a3417eacf4ba6401aea689cb1fc1d01..477cb1a6533f64d7610acd844e2d3c4388a79878 100644 (file)
--- a/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -875,12 +875,22 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
   Value *FirstDynamic = 0, *LastDynamic = 0;
 
   for (size_t i = 0; i < n; i++) {
+    static const size_t kMaxGlobalRedzone = 1 << 18;
     GlobalVariable *G = GlobalsToChange[i];
     PointerType *PtrTy = cast<PointerType>(G->getType());
     Type *Ty = PtrTy->getElementType();
     uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
-    size_t RZ = RedzoneSize();
-    uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
+    size_t MinRZ = RedzoneSize();
+    // MinRZ <= RZ <= kMaxGlobalRedzone
+    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
+    size_t RZ = std::max(MinRZ,
+                         std::min(kMaxGlobalRedzone,
+                                  (SizeInBytes / MinRZ / 4) * MinRZ));
+    uint64_t RightRedzoneSize = RZ;
+    // Round up to MinRZ
+    if (SizeInBytes % MinRZ)
+      RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
+    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
     Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
     // Determine whether this global should be poisoned in initialization.
     bool GlobalHasDynamicInitializer =
@@ -904,7 +914,7 @@ bool AddressSanitizerModule::runOnModule(Module &M) {
         M, NewTy, G->isConstant(), G->getLinkage(),
         NewInitializer, "", G, G->getThreadLocalMode());
     NewGlobal->copyAttributesFrom(G);
-    NewGlobal->setAlignment(RZ);
+    NewGlobal->setAlignment(MinRZ);
 
     Value *Indices2[2];
     Indices2[0] = IRB.getInt32(0);

diff --git a/test/Instrumentation/AddressSanitizer/adaptive_global_redzones.ll b/test/Instrumentation/AddressSanitizer/adaptive_global_redzones.ll
new file mode 100644 (file)
index 0000000..6a60d1c
--- /dev/null
+++ b/test/Instrumentation/AddressSanitizer/adaptive_global_redzones.ll
@@ -0,0 +1,57 @@
+; RUN: opt < %s -asan -asan-module -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Here we check that the global redzone sizes grow with the object size.
+
+@G10 = global [10 x i8] zeroinitializer, align 1
+; CHECK: @G10 = global { [10 x i8], [54 x i8] }
+
+@G31 = global [31 x i8] zeroinitializer, align 1
+@G32 = global [32 x i8] zeroinitializer, align 1
+@G33 = global [33 x i8] zeroinitializer, align 1
+; CHECK: @G31 = global { [31 x i8], [33 x i8] }
+; CHECK: @G32 = global { [32 x i8], [32 x i8] }
+; CHECK: @G33 = global { [33 x i8], [63 x i8] }
+
+@G63 = global [63 x i8] zeroinitializer, align 1
+@G64 = global [64 x i8] zeroinitializer, align 1
+@G65 = global [65 x i8] zeroinitializer, align 1
+; CHECK: @G63 = global { [63 x i8], [33 x i8] }
+; CHECK: @G64 = global { [64 x i8], [32 x i8] }
+; CHECK: @G65 = global { [65 x i8], [63 x i8] }
+
+@G127 = global [127 x i8] zeroinitializer, align 1
+@G128 = global [128 x i8] zeroinitializer, align 1
+@G129 = global [129 x i8] zeroinitializer, align 1
+; CHECK: @G127 = global { [127 x i8], [33 x i8] }
+; CHECK: @G128 = global { [128 x i8], [32 x i8] }
+; CHECK: @G129 = global { [129 x i8], [63 x i8] }
+
+@G255 = global [255 x i8] zeroinitializer, align 1
+@G256 = global [256 x i8] zeroinitializer, align 1
+@G257 = global [257 x i8] zeroinitializer, align 1
+; CHECK: @G255 = global { [255 x i8], [33 x i8] }
+; CHECK: @G256 = global { [256 x i8], [64 x i8] }
+; CHECK: @G257 = global { [257 x i8], [95 x i8] }
+
+@G511 = global [511 x i8] zeroinitializer, align 1
+@G512 = global [512 x i8] zeroinitializer, align 1
+@G513 = global [513 x i8] zeroinitializer, align 1
+; CHECK: @G511 = global { [511 x i8], [97 x i8] }
+; CHECK: @G512 = global { [512 x i8], [128 x i8] }
+; CHECK: @G513 = global { [513 x i8], [159 x i8] }
+
+@G1023 = global [1023 x i8] zeroinitializer, align 1
+@G1024 = global [1024 x i8] zeroinitializer, align 1
+@G1025 = global [1025 x i8] zeroinitializer, align 1
+; CHECK: @G1023 = global { [1023 x i8], [225 x i8] }
+; CHECK: @G1024 = global { [1024 x i8], [256 x i8] }
+; CHECK: @G1025 = global { [1025 x i8], [287 x i8] }
+
+@G1000000 = global [1000000 x i8] zeroinitializer, align 1
+@G10000000 = global [10000000 x i8] zeroinitializer, align 1
+@G100000000 = global [100000000 x i8] zeroinitializer, align 1
+; CHECK: @G1000000 = global { [1000000 x i8], [249984 x i8] }
+; CHECK: @G10000000 = global { [10000000 x i8], [262144 x i8] }
+; CHECK: @G100000000 = global { [100000000 x i8], [262144 x i8] }