[AArch64] [DFSan] Adding support of AArch64 for DFSan

[sdkie]

Summary

This patch require enabling DFSan in Clang,
and also adding ShadowPtrMask in LLVM.
I will also submit those patches for review.

[sdkie]

AAarch64 has only 39 addressable bits not like MIPS64 which has 40 addressable bits.

[rengolin]

In D9649#170955, @sdkie wrote:

AAarch64 has only 39 addressable bits not like MIPS64 which has 40 addressable bits.

Not all AArch64 is 39bits, some are 42bits.

We had this discussion in the ASAN side, and allowing 42bits made it work on those machines while it didn't increase memory footprint that much for 39bits, so assuming 42 was preferred. If here we have the same case, I'd guess taking the same assumption would be the way to go.

Please check with Kostya fist, though.

cheers,
--renato

[sdkie]

@rengolin

AAarch64 has only 39 addressable bits not like MIPS64 which has 40 addressable bits.

Not all AArch64 is 39bits, some are 42bits.

We had this discussion in the ASAN side, and allowing 42bits made it work on those machines while it didn't increase memory footprint that much for 39bits, so assuming 42 was preferred. If here we have the same case, I'd guess taking the same assumption would be the way to go.

In ASAN code I see

kAArch64_ShadowOffset64 = 1ULL << 36;

which will limit the upper memory to 0x7fffffffff.

[rengolin]

In D9649#170980, @sdkie wrote:

In ASAN code I see
kAArch64_ShadowOffset64 = 1ULL << 36;
which will limit the upper memory to 0x7fffffffff.

Yes, this has been discussed, but not applied. :)

I think it should be safe to assume 39bits for now, and let the discussion flow on all three ASAN/TSAN/DFSAN later to increase that value. Just giving you the heads up.

cheers,
--renato

[sdkie]

@kcc @pcc Did you got time to review my patches?

[pcc]

LGTM

[Eugene.Zelenko]

Committed in rL243688, probably independent development.

cmake/config-ix.cmake

 # LSan and UBSan common files should be available on all architectures supported
 # by other sanitizers (even if they build into dummy object files).
 filter_available_targets(LSAN_COMMON_SUPPORTED_ARCH
   ${SANITIZER_COMMON_SUPPORTED_ARCH})
 filter_available_targets(UBSAN_COMMON_SUPPORTED_ARCH
   ${SANITIZER_COMMON_SUPPORTED_ARCH})
 filter_available_targets(ASAN_SUPPORTED_ARCH
   x86_64 i386 i686 powerpc64 powerpc64le arm mips mipsel mips64 mips64el)
-filter_available_targets(DFSAN_SUPPORTED_ARCH x86_64 mips64 mips64el)
+filter_available_targets(DFSAN_SUPPORTED_ARCH x86_64 mips64 mips64el aarch64)
 filter_available_targets(LSAN_SUPPORTED_ARCH x86_64 mips64 mips64el)
 filter_available_targets(MSAN_SUPPORTED_ARCH x86_64 mips64 mips64el)
 filter_available_targets(PROFILE_SUPPORTED_ARCH x86_64 i386 i686 arm mips mips64
   mipsel mips64el aarch64 powerpc64 powerpc64le)
 filter_available_targets(TSAN_SUPPORTED_ARCH x86_64 mips64 mips64el)
 filter_available_targets(UBSAN_SUPPORTED_ARCH x86_64 i386 i686 arm aarch64 mips
   mipsel mips64 mips64el powerpc64 powerpc64le)
 

lib/dfsan/dfsan.h

 
 void InitializeInterceptors();
 
 inline dfsan_label *shadow_for(void *ptr) {
 #if defined(__x86_64__)
   return (dfsan_label *) ((((uptr) ptr) & ~0x700000000000) << 1);
 #elif defined(__mips64)
   return (dfsan_label *) ((((uptr) ptr) & ~0xF000000000) << 1);
+#elif defined(__aarch64__)
+  return (dfsan_label *) ((((uptr) ptr) & ~0x7000000000) << 1);
 #endif
 }
 
 inline const dfsan_label *shadow_for(const void *ptr) {
   return shadow_for(const_cast<void *>(ptr));
 }
 
 struct Flags {

lib/dfsan/dfsan.cc

 // +--------------------+ 0x2200000000 (kUnusedAddr)
 // |    union table     |
 // +--------------------+ 0x2000000000 (kUnionTableAddr)
 // |   shadow memory    |
 // +--------------------+ 0x0000010000 (kShadowAddr)
 // | reserved by kernel |
 // +--------------------+ 0x0000000000
 
+// On Linux/AArch64, memory is laid out as follows:
+//
+// +--------------------+ 0x8000000000 (top of memory)
+// | application memory |
+// +--------------------+ 0x7000008000 (kAppAddr)
+// |                    |
+// |       unused       |
+// |                    |
+// +--------------------+ 0x2200000000 (kUnusedAddr)
+// |    union table     |
+// +--------------------+ 0x2000000000 (kUnionTableAddr)
+// |   shadow memory    |
+// +--------------------+ 0x0000010000 (kShadowAddr)
+// | reserved by kernel |
+// +--------------------+ 0x0000000000
+
 typedef atomic_dfsan_label dfsan_union_table_t[kNumLabels][kNumLabels];
 
 #if defined(__x86_64__)
 static const uptr kShadowAddr = 0x10000;
 static const uptr kUnionTableAddr = 0x200000000000;
 static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
 static const uptr kAppAddr = 0x700000008000;
 #elif defined(__mips64)
 static const uptr kShadowAddr = 0x10000;
 static const uptr kUnionTableAddr = 0x2000000000;
 static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
 static const uptr kAppAddr = 0xF000008000;
+#elif defined(__aarch64__)
+static const uptr kShadowAddr = 0x10000;
+static const uptr kUnionTableAddr = 0x2000000000;
+static const uptr kUnusedAddr = kUnionTableAddr + sizeof(dfsan_union_table_t);
+static const uptr kAppAddr = 0x7000008000;
 #else
 # error "DFSan not supported for this platform!"
 #endif
 
 static atomic_dfsan_label *union_table(dfsan_label l1, dfsan_label l2) {
   return &(*(dfsan_union_table_t *) kUnionTableAddr)[l1][l2];
 }