[libc++] Upstream ptrauth support in libc++ and libc++abi (#84573)
This is an exact upstreaming of the downstream diff. Minor
simplifications can be made in the future but upstreaming as-is will
make it easier for us to deal with downstream merge conflicts.
Partially fixes #83805
GitOrigin-RevId: 98244c4e2acafb7568e8337088c6caaaffcb7831
diff --git a/src/private_typeinfo.cpp b/src/private_typeinfo.cpp
index 5c68f3e..9e58501 100644
--- a/src/private_typeinfo.cpp
+++ b/src/private_typeinfo.cpp
@@ -51,6 +51,21 @@
#include <atomic>
#endif
+#if __has_feature(ptrauth_calls)
+#include <ptrauth.h>
+#endif
+
+
+template<typename T>
+static inline
+T *
+get_vtable(T *vtable) {
+#if __has_feature(ptrauth_calls)
+ vtable = ptrauth_strip(vtable, ptrauth_key_cxx_vtable_pointer);
+#endif
+ return vtable;
+}
+
static inline
bool
is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
@@ -103,6 +118,7 @@
info->dynamic_type = *(reinterpret_cast<const __class_type_info* const*>(ptr_to_ti_proxy));
#else
void **vtable = *static_cast<void ** const *>(static_ptr);
+ vtable = get_vtable(vtable);
info->offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
info->dynamic_ptr = static_cast<const char*>(static_ptr) + info->offset_to_derived;
info->dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
@@ -561,6 +577,7 @@
offset_to_base = __offset_flags >> __offset_shift;
if (is_virtual) {
const char* vtable = *static_cast<const char* const*>(adjustedPtr);
+ vtable = get_vtable(vtable);
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
} else if (!is_virtual) {
@@ -1501,6 +1518,7 @@
if (__offset_flags & __virtual_mask)
{
const char* vtable = *static_cast<const char*const*>(current_ptr);
+ vtable = get_vtable(vtable);
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
__base_type->search_above_dst(info, dst_ptr,
@@ -1521,6 +1539,7 @@
if (__offset_flags & __virtual_mask)
{
const char* vtable = *static_cast<const char*const*>(current_ptr);
+ vtable = get_vtable(vtable);
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
__base_type->search_below_dst(info,