ARM MTE stack sanitizer.

Add "memtag" sanitizer that detects and mitigates stack memory issues
using armv8.5 Memory Tagging Extension.

It is similar in principle to HWASan, which is a software implementation
of the same idea, but there are enough differencies to warrant a new
sanitizer type IMHO. It is also expected to have very different
performance properties.

The new sanitizer does not have a runtime library (it may grow one
later, along with a "debugging" mode). Similar to SafeStack and
StackProtector, the instrumentation pass (in a follow up change) will be
inserted in all cases, but will only affect functions marked with the
new sanitize_memtag attribute.

Reviewers: pcc, hctim, vitalybuka, ostannard

Subscribers: srhines, mehdi_amini, javed.absar, kristof.beyls, hiraditya, cryptoad, steven_wu, dexonsmith, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D64169

llvm-svn: 366123

2 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 6cad3b94e5e..29dc7f61639 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1296,6 +1296,9 @@ static uint64_t getRawAttributeMask(Attribute::AttrKind Val) {
   case Attribute::AllocSize:
     llvm_unreachable("allocsize not supported in raw format");
     break;
+  case Attribute::SanitizeMemTag:
+    llvm_unreachable("sanitize_memtag attribute not supported in raw format");
+    break;
   }
   llvm_unreachable("Unsupported attribute type");
 }
@@ -1305,7 +1308,8 @@ static void addRawAttributeValue(AttrBuilder &B, uint64_t Val) {
 
   for (Attribute::AttrKind I = Attribute::None; I != Attribute::EndAttrKinds;
        I = Attribute::AttrKind(I + 1)) {
-    if (I == Attribute::Dereferenceable ||
+    if (I == Attribute::SanitizeMemTag ||
+        I == Attribute::Dereferenceable ||
         I == Attribute::DereferenceableOrNull ||
         I == Attribute::ArgMemOnly ||
         I == Attribute::AllocSize ||
@@ -1534,6 +1538,8 @@ static Attribute::AttrKind getAttrFromCode(uint64_t Code) {
     return Attribute::ZExt;
   case bitc::ATTR_KIND_IMMARG:
     return Attribute::ImmArg;
+  case bitc::ATTR_KIND_SANITIZE_MEMTAG:
+    return Attribute::SanitizeMemTag;
   }
 }
 
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index a23b44f4751..5c7b970a3a7 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -723,6 +723,8 @@ static uint64_t getAttrKindEncoding(Attribute::AttrKind Kind) {
     return bitc::ATTR_KIND_Z_EXT;
   case Attribute::ImmArg:
     return bitc::ATTR_KIND_IMMARG;
+  case Attribute::SanitizeMemTag:
+    return bitc::ATTR_KIND_SANITIZE_MEMTAG;
   case Attribute::EndAttrKinds:
     llvm_unreachable("Can not encode end-attribute kinds marker.");
   case Attribute::None: