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[libc++][libc++abi] Minor follow-up changes after ptrauth upstreaming #87481

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merged 5 commits into from
Jul 23, 2024
Merged

[libc++][libc++abi] Minor follow-up changes after ptrauth upstreaming #87481

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e3f9d75
[libc++][libc++abi] Minor follow-up changes after ptrauth upstreaming
ldionne Apr 3, 2024
de9fbd1
Formatting
ldionne Apr 3, 2024
3e0e1ea
Uglify and try to also handle ELF
ldionne Jun 7, 2024
9eb9186
Revert to previous feature check
ldionne Jul 18, 2024
e86c25d
Use ptrauth_type_info_vtable_pointer_discrimination instead
ldionne Jul 23, 2024
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9 changes: 5 additions & 4 deletions libcxx/include/typeinfo
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Original file line number Diff line number Diff line change
Expand Up @@ -275,13 +275,14 @@ struct __type_info_implementations {
__impl;
};

# if defined(__arm64__) && __has_cpp_attribute(clang::ptrauth_vtable_pointer)
# if __has_feature(ptrauth_type_info_discriminated_vtable_pointer)
# if __has_cpp_attribute(_Clang::__ptrauth_vtable_pointer__)
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# if __has_feature(ptrauth_type_info_vtable_pointer_discrimination)
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH \
[[clang::ptrauth_vtable_pointer(process_independent, address_discrimination, type_discrimination)]]
[[_Clang::__ptrauth_vtable_pointer__(process_independent, address_discrimination, type_discrimination)]]
# else
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH \
[[clang::ptrauth_vtable_pointer(process_independent, no_address_discrimination, no_extra_discrimination)]]
[[_Clang::__ptrauth_vtable_pointer__( \
process_independent, no_address_discrimination, no_extra_discrimination)]]
# endif
# else
# define _LIBCPP_TYPE_INFO_VTABLE_POINTER_AUTH
Expand Down
6 changes: 3 additions & 3 deletions libcxx/src/include/overridable_function.h
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Expand Up @@ -13,7 +13,7 @@
#include <__config>
#include <cstdint>

#if defined(__arm64e__) && __has_feature(ptrauth_calls)
#if __has_feature(ptrauth_calls)
# include <ptrauth.h>
#endif

Expand Down Expand Up @@ -83,13 +83,13 @@ _LIBCPP_HIDE_FROM_ABI bool __is_function_overridden(_Ret (*__fptr)(_Args...)) no
uintptr_t __end = reinterpret_cast<uintptr_t>(&__lcxx_override_end);
uintptr_t __ptr = reinterpret_cast<uintptr_t>(__fptr);

#if defined(__arm64e__) && __has_feature(ptrauth_calls)
# if __has_feature(ptrauth_calls)
// We must pass a void* to ptrauth_strip since it only accepts a pointer type. Also, in particular,
// we must NOT pass a function pointer, otherwise we will strip the function pointer, and then attempt
// to authenticate and re-sign it when casting it to a uintptr_t again, which will fail because we just
// stripped the function pointer. See rdar://122927845.
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__ptr = reinterpret_cast<uintptr_t>(ptrauth_strip(reinterpret_cast<void*>(__ptr), ptrauth_key_function_pointer));
#endif
# endif

// Finally, the function was overridden if it falls outside of the section's bounds.
return __ptr < __start || __ptr > __end;
Expand Down
33 changes: 13 additions & 20 deletions libcxxabi/src/private_typeinfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -55,15 +55,12 @@
#include <ptrauth.h>
#endif


template<typename T>
static inline
T *
get_vtable(T *vtable) {
template <typename T>
static inline T* strip_vtable(T* vtable) {
#if __has_feature(ptrauth_calls)
vtable = ptrauth_strip(vtable, ptrauth_key_cxx_vtable_pointer);
vtable = ptrauth_strip(vtable, ptrauth_key_cxx_vtable_pointer);
#endif
return vtable;
return vtable;
}

static inline
Expand Down Expand Up @@ -117,11 +114,10 @@ void dyn_cast_get_derived_info(derived_object_info* info, const void* static_ptr
reinterpret_cast<const uint8_t*>(vtable) + offset_to_ti_proxy;
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]);
void** vtable = strip_vtable(*static_cast<void** const*>(static_ptr));
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]);
#endif
}

Expand Down Expand Up @@ -576,8 +572,7 @@ __base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
find the layout. */
offset_to_base = __offset_flags >> __offset_shift;
if (is_virtual) {
const char* vtable = *static_cast<const char* const*>(adjustedPtr);
vtable = get_vtable(vtable);
const char* vtable = strip_vtable(*static_cast<const char* const*>(adjustedPtr));
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
} else if (!is_virtual) {
Expand Down Expand Up @@ -1517,9 +1512,8 @@ __base_class_type_info::search_above_dst(__dynamic_cast_info* info,
ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
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);
const char* vtable = strip_vtable(*static_cast<const char* const*>(current_ptr));
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
__base_type->search_above_dst(info, dst_ptr,
static_cast<const char*>(current_ptr) + offset_to_base,
Expand All @@ -1538,9 +1532,8 @@ __base_class_type_info::search_below_dst(__dynamic_cast_info* info,
ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
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);
const char* vtable = strip_vtable(*static_cast<const char* const*>(current_ptr));
offset_to_base = update_offset_to_base(vtable, offset_to_base);
}
__base_type->search_below_dst(info,
static_cast<const char*>(current_ptr) + offset_to_base,
Expand Down
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