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//===-- hwasan_globals.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 HWAddressSanitizer.
//
// HWAddressSanitizer globals-specific runtime.
//===----------------------------------------------------------------------===//
#include "hwasan_globals.h"
#include "sanitizer_common/sanitizer_array_ref.h"
namespace __hwasan {
enum { NT_LLVM_HWASAN_GLOBALS = 3 };
struct hwasan_global_note {
s32 begin_relptr;
s32 end_relptr;
};
// Check that the given library meets the code model requirements for tagged
// globals. These properties are not checked at link time so they need to be
// checked at runtime.
static void CheckCodeModel(ElfW(Addr) base, const ElfW(Phdr) * phdr,
ElfW(Half) phnum) {
ElfW(Addr) min_addr = -1ull, max_addr = 0;
for (unsigned i = 0; i != phnum; ++i) {
if (phdr[i].p_type != PT_LOAD)
continue;
ElfW(Addr) lo = base + phdr[i].p_vaddr, hi = lo + phdr[i].p_memsz;
if (min_addr > lo)
min_addr = lo;
if (max_addr < hi)
max_addr = hi;
}
if (max_addr - min_addr > 1ull << 32) {
Report("FATAL: HWAddressSanitizer: library size exceeds 2^32\n");
Die();
}
if (max_addr > 1ull << 48) {
Report("FATAL: HWAddressSanitizer: library loaded above address 2^48\n");
Die();
}
}
ArrayRef<const hwasan_global> HwasanGlobalsFor(ElfW(Addr) base,
const ElfW(Phdr) * phdr,
ElfW(Half) phnum) {
// Read the phdrs from this DSO.
for (unsigned i = 0; i != phnum; ++i) {
if (phdr[i].p_type != PT_NOTE)
continue;
const char *note = reinterpret_cast<const char *>(base + phdr[i].p_vaddr);
const char *nend = note + phdr[i].p_memsz;
// Traverse all the notes until we find a HWASan note.
while (note < nend) {
auto *nhdr = reinterpret_cast<const ElfW(Nhdr) *>(note);
const char *name = note + sizeof(ElfW(Nhdr));
const char *desc = name + RoundUpTo(nhdr->n_namesz, 4);
// Discard non-HWASan-Globals notes.
if (nhdr->n_type != NT_LLVM_HWASAN_GLOBALS ||
internal_strcmp(name, "LLVM") != 0) {
note = desc + RoundUpTo(nhdr->n_descsz, 4);
continue;
}
// Only libraries with instrumented globals need to be checked against the
// code model since they use relocations that aren't checked at link time.
CheckCodeModel(base, phdr, phnum);
auto *global_note = reinterpret_cast<const hwasan_global_note *>(desc);
auto *globals_begin = reinterpret_cast<const hwasan_global *>(
note + global_note->begin_relptr);
auto *globals_end = reinterpret_cast<const hwasan_global *>(
note + global_note->end_relptr);
return {globals_begin, globals_end};
}
}
return {};
}
} // namespace __hwasan
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