[llvm] r329228 - hwasan: add -hwasan-match-all-tag flag

[Evgeniy Stepanov via llvm-commits]

Author: eugenis
Date: Wed Apr  4 13:44:59 2018
New Revision: 329228

URL: http://llvm.org/viewvc/llvm-project?rev=329228&view=rev
Log:
hwasan: add -hwasan-match-all-tag flag

Sometimes instead of storing addresses as is, the kernel stores the address of
a page and an offset within that page, and then computes the actual address
when it needs to make an access. Because of this the pointer tag gets lost
(gets set to 0xff). The solution is to ignore all accesses tagged with 0xff.

This patch adds a -hwasan-match-all-tag flag to hwasan, which allows to ignore
accesses through pointers with a particular pointer tag value for validity.

Patch by Andrey Konovalov.

Differential Revision: https://reviews.llvm.org/D44827

Modified:
    llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
    llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel.ll

Modified: llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp?rev=329228&r1=329227&r2=329228&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp Wed Apr  4 13:44:59 2018
@@ -101,6 +101,11 @@ static cl::opt<unsigned long long> ClMap
     cl::desc("offset of hwasan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
     cl::init(0));
 
+static cl::opt<int> ClMatchAllTag(
+    "hwasan-match-all-tag",
+    cl::desc("don't report bad accesses via pointers with this tag"), cl::Hidden,
+    cl::init(-1));
+
 static cl::opt<bool> ClEnableKhwasan(
     "hwasan-kernel", cl::desc("Enable KernelHWAddressSanitizer instrumentation"),
     cl::Hidden, cl::init(false));
@@ -330,6 +335,12 @@ void HWAddressSanitizer::instrumentMemAc
       IRB.CreateLoad(IRB.CreateIntToPtr(ShadowLong, IRB.getInt8PtrTy()));
   Value *TagMismatch = IRB.CreateICmpNE(PtrTag, MemTag);
 
+  if (ClMatchAllTag != -1) {
+    Value *TagNotIgnored = IRB.CreateICmpNE(PtrTag,
+        ConstantInt::get(PtrTag->getType(), ClMatchAllTag));
+    TagMismatch = IRB.CreateAnd(TagMismatch, TagNotIgnored);
+  }
+
   TerminatorInst *CheckTerm =
       SplitBlockAndInsertIfThen(TagMismatch, InsertBefore, !Recover,
                                 MDBuilder(*C).createBranchWeights(1, 100000));

Modified: llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel.ll?rev=329228&r1=329227&r2=329228&view=diff
==============================================================================
--- llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel.ll (original)
+++ llvm/trunk/test/Instrumentation/HWAddressSanitizer/kernel.ll Wed Apr  4 13:44:59 2018
@@ -1,10 +1,11 @@
 ; Test kernel hwasan instrumentation.
 ;
 ; RUN: opt < %s -hwasan -hwasan-kernel=1 -S | FileCheck %s --allow-empty --check-prefixes=INIT
-; RUN: opt < %s -hwasan -hwasan-kernel=1 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET
-; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-mapping-offset=12345678 -S | FileCheck %s  --check-prefixes=CHECK,OFFSET
-; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-recover=0 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,ABORT
-; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-recover=1 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,RECOVER
+; RUN: opt < %s -hwasan -hwasan-kernel=1 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,NO-MATCH-ALL
+; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-mapping-offset=12345678 -S | FileCheck %s  --check-prefixes=CHECK,OFFSET,NO-MATCH-ALL
+; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-recover=0 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,ABORT,NO-MATCH-ALL
+; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-recover=1 -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,RECOVER,NO-MATCH-ALL
+; RUN: opt < %s -hwasan -hwasan-kernel=1 -hwasan-recover=1 -hwasan-match-all-tag=0xff -S | FileCheck %s  --check-prefixes=CHECK,NOOFFSET,RECOVER,MATCH-ALL
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64--linux-android"
@@ -24,7 +25,12 @@ define i8 @test_load(i8* %a) sanitize_hw
 
 ; CHECK: %[[MEMTAG:[^ ]*]] = load i8, i8* %[[E]]
 ; CHECK: %[[F:[^ ]*]] = icmp ne i8 %[[PTRTAG]], %[[MEMTAG]]
-; CHECK: br i1 %[[F]], label {{.*}}, label {{.*}}, !prof {{.*}}
+
+; MATCH-ALL: %[[G:[^ ]*]] = icmp ne i8 %[[PTRTAG]], -1
+; MATCH-ALL: %[[H:[^ ]*]] = and i1 %[[F]], %[[G]]
+; MATCH-ALL: br i1 %[[H]], label {{.*}}, label {{.*}}, !prof {{.*}}
+
+; NO-MATCH-ALL: br i1 %[[F]], label {{.*}}, label {{.*}}, !prof {{.*}}
 
 ; ABORT: call void asm sideeffect "brk #2304", "{x0}"(i64 %[[A]])
 ; ABORT: unreachable