mirror of
git://gcc.gnu.org/git/gcc.git
synced 2024-11-28 12:30:50 +08:00
66 lines
2.2 KiB
C++
66 lines
2.2 KiB
C++
//===-- asan_premap_shadow.cpp --------------------------------------------===//
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file is a part of AddressSanitizer, an address sanity checker.
|
|
//
|
|
// Reserve shadow memory with an ifunc resolver.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "asan_mapping.h"
|
|
|
|
#if ASAN_PREMAP_SHADOW
|
|
|
|
#include "asan_premap_shadow.h"
|
|
#include "sanitizer_common/sanitizer_posix.h"
|
|
|
|
namespace __asan {
|
|
|
|
// The code in this file needs to run in an unrelocated binary. It may not
|
|
// access any external symbol, including its own non-hidden globals.
|
|
|
|
// Conservative upper limit.
|
|
uptr PremapShadowSize() {
|
|
uptr granularity = GetMmapGranularity();
|
|
return RoundUpTo(GetMaxVirtualAddress() >> ASAN_SHADOW_SCALE, granularity);
|
|
}
|
|
|
|
// Returns an address aligned to 8 pages, such that one page on the left and
|
|
// PremapShadowSize() bytes on the right of it are mapped r/o.
|
|
uptr PremapShadow() {
|
|
return MapDynamicShadow(PremapShadowSize(), /*mmap_alignment_scale*/ 3,
|
|
/*min_shadow_base_alignment*/ 0, kHighMemEnd,
|
|
GetMmapGranularity());
|
|
}
|
|
|
|
bool PremapShadowFailed() {
|
|
uptr shadow = reinterpret_cast<uptr>(&__asan_shadow);
|
|
uptr resolver = reinterpret_cast<uptr>(&__asan_premap_shadow);
|
|
// shadow == resolver is how Android KitKat and older handles ifunc.
|
|
// shadow == 0 just in case.
|
|
if (shadow == 0 || shadow == resolver)
|
|
return true;
|
|
return false;
|
|
}
|
|
} // namespace __asan
|
|
|
|
extern "C" {
|
|
decltype(__asan_shadow)* __asan_premap_shadow() {
|
|
// The resolver may be called multiple times. Map the shadow just once.
|
|
static uptr premapped_shadow = 0;
|
|
if (!premapped_shadow) premapped_shadow = __asan::PremapShadow();
|
|
return reinterpret_cast<decltype(__asan_shadow)*>(premapped_shadow);
|
|
}
|
|
|
|
// __asan_shadow is a "function" that has the same address as the first byte of
|
|
// the shadow mapping.
|
|
INTERFACE_ATTRIBUTE __attribute__((ifunc("__asan_premap_shadow"))) void
|
|
__asan_shadow();
|
|
}
|
|
|
|
#endif // ASAN_PREMAP_SHADOW
|