[compiler-rt] 64fa90b - [hwasan] Add `__hwasan_get_tag_from_pointer` (#75267)

[via llvm-commits]

Author: Vitaly Buka
Date: 2023-12-13T11:22:10-08:00
New Revision: 64fa90bf8966cb886463840e5c85b9602cbbdc52

URL: https://github.com/llvm/llvm-project/commit/64fa90bf8966cb886463840e5c85b9602cbbdc52
DIFF: https://github.com/llvm/llvm-project/commit/64fa90bf8966cb886463840e5c85b9602cbbdc52.diff

LOG: [hwasan] Add `__hwasan_get_tag_from_pointer` (#75267)

This simplifies handling tags by user code. Now code does not need
to know bit size of tag and its position.

Added: 
    compiler-rt/test/hwasan/TestCases/tag-ptr.cpp

Modified: 
    compiler-rt/include/sanitizer/hwasan_interface.h
    compiler-rt/lib/hwasan/hwasan.cpp
    compiler-rt/lib/hwasan/hwasan.h
    compiler-rt/lib/hwasan/hwasan_interface_internal.h

Removed: 
    


################################################################################
diff  --git a/compiler-rt/include/sanitizer/hwasan_interface.h b/compiler-rt/include/sanitizer/hwasan_interface.h
index abe310c0666948..407f488a24a617 100644
--- a/compiler-rt/include/sanitizer/hwasan_interface.h
+++ b/compiler-rt/include/sanitizer/hwasan_interface.h
@@ -44,6 +44,10 @@ void SANITIZER_CDECL __hwasan_tag_memory(const volatile void *p,
 void *SANITIZER_CDECL __hwasan_tag_pointer(const volatile void *p,
                                            unsigned char tag);
 
+/// Get tag from the pointer.
+unsigned char SANITIZER_CDECL
+__hwasan_get_tag_from_pointer(const volatile void *p);
+
 // Set memory tag from the current SP address to the given address to zero.
 // This is meant to annotate longjmp and other non-local jumps.
 // This function needs to know the (almost) exact destination frame address;

diff  --git a/compiler-rt/lib/hwasan/hwasan.cpp b/compiler-rt/lib/hwasan/hwasan.cpp
index 2f6cb10caf1be6..52780becbdb264 100644
--- a/compiler-rt/lib/hwasan/hwasan.cpp
+++ b/compiler-rt/lib/hwasan/hwasan.cpp
@@ -678,6 +678,8 @@ uptr __hwasan_tag_pointer(uptr p, u8 tag) {
   return AddTagToPointer(p, tag);
 }
 
+u8 __hwasan_get_tag_from_pointer(uptr p) { return GetTagFromPointer(p); }
+
 void __hwasan_handle_longjmp(const void *sp_dst) {
   uptr dst = (uptr)sp_dst;
   // HWASan does not support tagged SP.

diff  --git a/compiler-rt/lib/hwasan/hwasan.h b/compiler-rt/lib/hwasan/hwasan.h
index 37ef4822285110..df21375e81671f 100644
--- a/compiler-rt/lib/hwasan/hwasan.h
+++ b/compiler-rt/lib/hwasan/hwasan.h
@@ -104,9 +104,9 @@ static inline void *UntagPtr(const void *tagged_ptr) {
 }
 
 static inline uptr AddTagToPointer(uptr p, tag_t tag) {
-  return InTaggableRegion(p)
-             ? ((p & ~kAddressTagMask) | ((uptr)tag << kAddressTagShift))
-             : p;
+  return InTaggableRegion(p) ? ((p & ~kAddressTagMask) |
+                                ((uptr)(tag & kTagMask) << kAddressTagShift))
+                             : p;
 }
 
 namespace __hwasan {

diff  --git a/compiler-rt/lib/hwasan/hwasan_interface_internal.h b/compiler-rt/lib/hwasan/hwasan_interface_internal.h
index e7804cc4903343..8f2f77dad917d2 100644
--- a/compiler-rt/lib/hwasan/hwasan_interface_internal.h
+++ b/compiler-rt/lib/hwasan/hwasan_interface_internal.h
@@ -160,6 +160,9 @@ void __hwasan_tag_memory(uptr p, u8 tag, uptr sz);
 SANITIZER_INTERFACE_ATTRIBUTE
 uptr __hwasan_tag_pointer(uptr p, u8 tag);
 
+SANITIZER_INTERFACE_ATTRIBUTE
+u8 __hwasan_get_tag_from_pointer(uptr p);
+
 SANITIZER_INTERFACE_ATTRIBUTE
 void __hwasan_tag_mismatch(uptr addr, u8 ts);
 

diff  --git a/compiler-rt/test/hwasan/TestCases/tag-ptr.cpp b/compiler-rt/test/hwasan/TestCases/tag-ptr.cpp
new file mode 100644
index 00000000000000..2f00e7913bb155
--- /dev/null
+++ b/compiler-rt/test/hwasan/TestCases/tag-ptr.cpp
@@ -0,0 +1,24 @@
+// RUN: %clangxx_hwasan -O0 %s -o %t && %run %t
+
+#include <assert.h>
+#include <memory>
+#include <sanitizer/hwasan_interface.h>
+#include <set>
+#include <stdio.h>
+
+int main() {
+  auto p = std::make_unique<char>();
+  std::set<void *> ptrs;
+  for (unsigned i = 0;; ++i) {
+    void *ptr = __hwasan_tag_pointer(p.get(), i);
+    if (!ptrs.insert(ptr).second)
+      break;
+    fprintf(stderr, "%p, %u, %u\n", ptr, i, __hwasan_get_tag_from_pointer(ptr));
+    assert(__hwasan_get_tag_from_pointer(ptr) == i);
+  }
+#ifdef __x86_64__
+  assert(ptrs.size() == 8);
+#else
+  assert(ptrs.size() == 256);
+#endif
+}