[llvm] 36eaeaf - [llvm][hwasan] Add Fuchsia shadow mapping configuration

[Leonard Chan via llvm-commits]

Author: Leonard Chan
Date: 2021-03-25T15:28:59-07:00
New Revision: 36eaeaf728d303c5b42c4d22724406b14b9f0f56

URL: https://github.com/llvm/llvm-project/commit/36eaeaf728d303c5b42c4d22724406b14b9f0f56
DIFF: https://github.com/llvm/llvm-project/commit/36eaeaf728d303c5b42c4d22724406b14b9f0f56.diff

LOG: [llvm][hwasan] Add Fuchsia shadow mapping configuration

Ensure that Fuchsia shadow memory starts at zero.

Differential Revision: https://reviews.llvm.org/D99380

Added: 
    llvm/test/Instrumentation/HWAddressSanitizer/fuchsia.ll

Modified: 
    llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index 07892bdc854b..04761f0d89f0 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -1531,7 +1531,13 @@ void HWAddressSanitizer::instrumentPersonalityFunctions() {
 void HWAddressSanitizer::ShadowMapping::init(Triple &TargetTriple,
                                              bool InstrumentWithCalls) {
   Scale = kDefaultShadowScale;
-  if (ClMappingOffset.getNumOccurrences() > 0) {
+  if (TargetTriple.isOSFuchsia()) {
+    // Fuchsia is always PIE, which means that the beginning of the address
+    // space is always available.
+    InGlobal = false;
+    InTls = false;
+    Offset = 0;
+  } else if (ClMappingOffset.getNumOccurrences() > 0) {
     InGlobal = false;
     InTls = false;
     Offset = ClMappingOffset;

diff  --git a/llvm/test/Instrumentation/HWAddressSanitizer/fuchsia.ll b/llvm/test/Instrumentation/HWAddressSanitizer/fuchsia.ll
new file mode 100644
index 000000000000..900583000835
--- /dev/null
+++ b/llvm/test/Instrumentation/HWAddressSanitizer/fuchsia.ll
@@ -0,0 +1,9 @@
+; Check HWASan shadow mapping on Fuchsia.
+; RUN: opt -hwasan -S -mtriple=aarch64-unknown-fuchsia < %s | FileCheck %s
+
+define i32 @test_load(i32* %a) sanitize_hwaddress {
+; CHECK: %.hwasan.shadow = call i8* asm "", "=r,0"(i8* null)
+entry:
+  %x = load i32, i32* %a, align 4
+  ret i32 %x
+}