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//===-- tsan_platform_posix.cpp -------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file is a part of ThreadSanitizer (TSan), a race detector.
// POSIX-specific code.
#include "sanitizer_common/sanitizer_platform.h"
# include <dlfcn.h>
# include "sanitizer_common/sanitizer_common.h"
# include "sanitizer_common/sanitizer_errno.h"
# include "sanitizer_common/sanitizer_libc.h"
# include "sanitizer_common/sanitizer_procmaps.h"
# include "tsan_platform.h"
# include "tsan_rtl.h"
namespace __tsan {
static const char kShadowMemoryMappingWarning[] =
"FATAL: %s can not madvise shadow region [%zx, %zx] with %s (errno: %d)\n";
static const char kShadowMemoryMappingHint[] =
"HINT: if %s is not supported in your environment, you may set "
static void DontDumpShadow(uptr addr, uptr size) {
if (common_flags()->use_madv_dontdump)
if (!DontDumpShadowMemory(addr, size)) {
Printf(kShadowMemoryMappingWarning, SanitizerToolName, addr, addr + size,
"MADV_DONTDUMP", errno);
Printf(kShadowMemoryMappingHint, "MADV_DONTDUMP", "use_madv_dontdump");
void InitializeShadowMemory() {
// Map memory shadow.
if (!MmapFixedSuperNoReserve(ShadowBeg(), ShadowEnd() - ShadowBeg(),
"shadow")) {
Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
// This memory range is used for thread stacks and large user mmaps.
// Frequently a thread uses only a small part of stack and similarly
// a program uses a small part of large mmap. On some programs
// we see 20% memory usage reduction without huge pages for this range.
DontDumpShadow(ShadowBeg(), ShadowEnd() - ShadowBeg());
DPrintf("memory shadow: %zx-%zx (%zuGB)\n",
ShadowBeg(), ShadowEnd(),
(ShadowEnd() - ShadowBeg()) >> 30);
// Map meta shadow.
const uptr meta = MetaShadowBeg();
const uptr meta_size = MetaShadowEnd() - meta;
if (!MmapFixedSuperNoReserve(meta, meta_size, "meta shadow")) {
Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
DontDumpShadow(meta, meta_size);
DPrintf("meta shadow: %zx-%zx (%zuGB)\n",
meta, meta + meta_size, meta_size >> 30);
on_initialize = reinterpret_cast<void (*)(void)>(
dlsym(RTLD_DEFAULT, "__tsan_on_initialize"));
on_finalize =
reinterpret_cast<int (*)(int)>(dlsym(RTLD_DEFAULT, "__tsan_on_finalize"));
static bool TryProtectRange(uptr beg, uptr end) {
CHECK_LE(beg, end);
if (beg == end)
return true;
return beg == (uptr)MmapFixedNoAccess(beg, end - beg);
static void ProtectRange(uptr beg, uptr end) {
if (!TryProtectRange(beg, end)) {
Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
Printf("FATAL: Make sure you are not using unlimited stack\n");
void CheckAndProtect() {
// Ensure that the binary is indeed compiled with -pie.
MemoryMappingLayout proc_maps(true);
MemoryMappedSegment segment;
while (proc_maps.Next(&segment)) {
if (IsAppMem(segment.start)) continue;
if (segment.start >= HeapMemEnd() && segment.start < HeapEnd()) continue;
if ( == 0) // Zero page or mprotected.
if (segment.start >= VdsoBeg()) // vdso
Printf("FATAL: ThreadSanitizer: unexpected memory mapping 0x%zx-0x%zx\n",
segment.start, segment.end);
# if defined(__aarch64__) && defined(__APPLE__) && SANITIZER_IOS
ProtectRange(HeapMemEnd(), ShadowBeg());
ProtectRange(ShadowEnd(), MetaShadowBeg());
ProtectRange(MetaShadowEnd(), TraceMemBeg());
ProtectRange(LoAppMemEnd(), ShadowBeg());
ProtectRange(ShadowEnd(), MetaShadowBeg());
if (MidAppMemBeg()) {
ProtectRange(MetaShadowEnd(), MidAppMemBeg());
ProtectRange(MidAppMemEnd(), TraceMemBeg());
} else {
ProtectRange(MetaShadowEnd(), TraceMemBeg());
// Memory for traces is mapped lazily in MapThreadTrace.
// Protect the whole range for now, so that user does not map something here.
ProtectRange(TraceMemBeg(), TraceMemEnd());
ProtectRange(TraceMemEnd(), HeapMemBeg());
ProtectRange(HeapEnd(), HiAppMemBeg());
#if defined(__s390x__)
// Protect the rest of the address space.
const uptr user_addr_max_l4 = 0x0020000000000000ull;
const uptr user_addr_max_l5 = 0xfffffffffffff000ull;
// All the maintained s390x kernels support at least 4-level page tables.
ProtectRange(HiAppMemEnd(), user_addr_max_l4);
// Older s390x kernels may not support 5-level page tables.
TryProtectRange(user_addr_max_l4, user_addr_max_l5);
} // namespace __tsan