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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.

llvm-svn: 249753
This commit is contained in:
Evgeniy Stepanov 2015-10-08 21:35:26 +00:00
parent 4729064a1c
commit d12212bc8c
2 changed files with 21 additions and 11 deletions
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22
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
View File

@ -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;
}

10
llvm/test/Instrumentation/MemorySanitizer/origin-alignment.ll
View File

@ -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