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From 2c87d24da09ecd2c14c38a0b4f7a0e3f332b08ee Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Thu, 8 Oct 2015 21:35:26 +0000
Subject: [PATCH] New MSan mapping layout (llvm part).
This is an implementation of
https://github.com/google/sanitizers/issues/579
It has a number of advantages over the current mapping:
* Works for non-PIE executables.
* Does not require ASLR; as a consequence, debugging MSan programs in
gdb no longer requires "set disable-randomization off".
* Supports linux kernels >=4.1.2.
* The code is marginally faster and smaller.
This is an ABI break. We never really promised ABI stability, but
this patch includes a courtesy escape hatch: a compile-time macro
that reverts back to the old mapping layout.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249753 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/Transforms/Instrumentation/MemorySanitizer.cpp | 22 +++++++++++++++-------
.../MemorySanitizer/origin-alignment.ll | 10 ++++++----
2 files changed, 21 insertions(+), 11 deletions(-)
diff --git a/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index 9d4c7de..bc6da5a 100644
--- a/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -232,10 +232,17 @@ static const MemoryMapParams Linux_I386_MemoryMapParams = {
// x86_64 Linux
static const MemoryMapParams Linux_X86_64_MemoryMapParams = {
+#ifdef MSAN_LINUX_X86_64_OLD_MAPPING
0x400000000000, // AndMask
0, // XorMask (not used)
0, // ShadowBase (not used)
0x200000000000, // OriginBase
+#else
+ 0, // AndMask (not used)
+ 0x500000000000, // XorMask
+ 0, // ShadowBase (not used)
+ 0x100000000000, // OriginBase
+#endif
};
// mips64 Linux
@@ -926,16 +933,17 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
///
/// Offset = (Addr & ~AndMask) ^ XorMask
Value *getShadowPtrOffset(Value *Addr, IRBuilder<> &IRB) {
+ Value *OffsetLong = IRB.CreatePointerCast(Addr, MS.IntptrTy);
+
uint64_t AndMask = MS.MapParams->AndMask;
- assert(AndMask != 0 && "AndMask shall be specified");
- Value *OffsetLong =
- IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy),
- ConstantInt::get(MS.IntptrTy, ~AndMask));
+ if (AndMask)
+ OffsetLong =
+ IRB.CreateAnd(OffsetLong, ConstantInt::get(MS.IntptrTy, ~AndMask));
uint64_t XorMask = MS.MapParams->XorMask;
- if (XorMask != 0)
- OffsetLong = IRB.CreateXor(OffsetLong,
- ConstantInt::get(MS.IntptrTy, XorMask));
+ if (XorMask)
+ OffsetLong =
+ IRB.CreateXor(OffsetLong, ConstantInt::get(MS.IntptrTy, XorMask));
return OffsetLong;
}
diff --git a/test/Instrumentation/MemorySanitizer/origin-alignment.ll b/test/Instrumentation/MemorySanitizer/origin-alignment.ll
index ce0dbfc..562d194 100644
--- a/test/Instrumentation/MemorySanitizer/origin-alignment.ll
+++ b/test/Instrumentation/MemorySanitizer/origin-alignment.ll
@@ -24,7 +24,7 @@ entry:
; CHECK-ORIGINS1: [[ORIGIN:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN0:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN:%[01-9a-z]+]] = call i32 @__msan_chain_origin(i32 [[ORIGIN0]])
-; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 add (i64 and (i64 ptrtoint {{.*}} to i32*), align 8
+; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 add (i64 xor (i64 ptrtoint (i8* @a8 to i64), i64 {{.*}}), i64 {{.*}}) to i32*), align 8
; CHECK: ret void
@@ -39,7 +39,7 @@ entry:
; CHECK-ORIGINS1: [[ORIGIN:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN0:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN:%[01-9a-z]+]] = call i32 @__msan_chain_origin(i32 [[ORIGIN0]])
-; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 add (i64 and (i64 ptrtoint {{.*}} to i32*), align 4
+; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 add (i64 xor (i64 ptrtoint (i8* @a4 to i64), i64 {{.*}}), i64 {{.*}}) to i32*), align 4
; CHECK: ret void
@@ -54,7 +54,8 @@ entry:
; CHECK-ORIGINS1: [[ORIGIN:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN0:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN:%[01-9a-z]+]] = call i32 @__msan_chain_origin(i32 [[ORIGIN0]])
-; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 and (i64 add (i64 and (i64 ptrtoint {{.*}} i64 -4) to i32*), align 4
+; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 and (i64 add (i64 xor (i64 ptrtoint (i8* @a2 to i64), i64 {{.*}}), i64 {{.*}}), i64 -4) to i32*), align 4
+
; CHECK: ret void
@@ -69,5 +70,6 @@ entry:
; CHECK-ORIGINS1: [[ORIGIN:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN0:%[01-9a-z]+]] = load {{.*}} @__msan_param_origin_tls
; CHECK-ORIGINS2: [[ORIGIN:%[01-9a-z]+]] = call i32 @__msan_chain_origin(i32 [[ORIGIN0]])
-; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 and (i64 add (i64 and (i64 ptrtoint {{.*}} i64 -4) to i32*), align 4
+; CHECK: store i32 [[ORIGIN]], i32* inttoptr (i64 and (i64 add (i64 xor (i64 ptrtoint (i8* @a1 to i64), i64 {{.*}}), i64 {{.*}}), i64 -4) to i32*), align 4
+
; CHECK: ret void
--
2.6.1
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