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//===-- hwasan_poisoning.cpp ------------------------------------*- C++ -*-===//
//
// 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 HWAddressSanitizer.
//
//===----------------------------------------------------------------------===//
#include "hwasan_poisoning.h"
#include "hwasan_mapping.h"
#include "interception/interception.h"
#include "sanitizer_common/sanitizer_common.h"
#include "sanitizer_common/sanitizer_linux.h"
namespace __hwasan {
uptr TagMemoryAligned(uptr p, uptr size, tag_t tag) {
CHECK(IsAligned(p, kShadowAlignment));
CHECK(IsAligned(size, kShadowAlignment));
uptr shadow_start = MemToShadow(p);
uptr shadow_size = MemToShadowSize(size);
uptr page_size = GetPageSizeCached();
uptr page_start = RoundUpTo(shadow_start, page_size);
uptr page_end = RoundDownTo(shadow_start + shadow_size, page_size);
uptr threshold = common_flags()->clear_shadow_mmap_threshold;
if (SANITIZER_LINUX &&
UNLIKELY(page_end >= page_start + threshold && tag == 0)) {
internal_memset((void *)shadow_start, tag, page_start - shadow_start);
internal_memset((void *)page_end, tag,
shadow_start + shadow_size - page_end);
// For an anonymous private mapping MADV_DONTNEED will return a zero page on
// Linux.
ReleaseMemoryPagesToOSAndZeroFill(page_start, page_end);
} else {
internal_memset((void *)shadow_start, tag, shadow_size);
}
return AddTagToPointer(p, tag);
}
uptr TagMemory(uptr p, uptr size, tag_t tag) {
uptr start = RoundDownTo(p, kShadowAlignment);
uptr end = RoundUpTo(p + size, kShadowAlignment);
return TagMemoryAligned(start, end - start, tag);
}
} // namespace __hwasan
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