[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.
diff --git a/compiler-rt/include/sanitizer/hwasan_interface.h b/compiler-rt/include/sanitizer/hwasan_interface.h
index abe310c..407f488 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_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 2f6cb10..52780be 100644
--- a/compiler-rt/lib/hwasan/hwasan.cpp
+++ b/compiler-rt/lib/hwasan/hwasan.cpp
@@ -678,6 +678,8 @@
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 37ef482..df21375 100644
--- a/compiler-rt/lib/hwasan/hwasan.h
+++ b/compiler-rt/lib/hwasan/hwasan.h
@@ -104,9 +104,9 @@
}
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 e7804cc..8f2f77d 100644
--- a/compiler-rt/lib/hwasan/hwasan_interface_internal.h
+++ b/compiler-rt/lib/hwasan/hwasan_interface_internal.h
@@ -161,6 +161,9 @@
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);
SANITIZER_INTERFACE_ATTRIBUTE
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 0000000..2f00e79
--- /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
+}
