libsanitizer/tsan/tsan_platform_linux.cc - chromiumos/third_party/gcc - Git at Google

 //===-- tsan_platform_linux.cc --------------------------------------------===//
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file is a part of ThreadSanitizer (TSan), a race detector.
 //
 // Linux-specific code.
 //===----------------------------------------------------------------------===//


 #include "sanitizer_common/sanitizer_platform.h"
 #if SANITIZER_LINUX

 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_libc.h"
 #include "sanitizer_common/sanitizer_procmaps.h"
 #include "sanitizer_common/sanitizer_stoptheworld.h"
 #include "tsan_platform.h"
 #include "tsan_rtl.h"
 #include "tsan_flags.h"

 #include <fcntl.h>
 #include <pthread.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdarg.h>
 #include <sys/mman.h>
 #include <sys/prctl.h>
 #include <sys/syscall.h>
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <unistd.h>
 #include <errno.h>
 #include <sched.h>
 #include <dlfcn.h>
 #define __need_res_state
 #include <resolv.h>
 #include <malloc.h>

 #ifdef sa_handler
 # undef sa_handler
 #endif

 #ifdef sa_sigaction
 # undef sa_sigaction
 #endif

 extern "C" struct mallinfo __libc_mallinfo();

 namespace __tsan {

 const uptr kPageSize = 4096;

 #ifndef TSAN_GO
 ScopedInRtl::ScopedInRtl()
     : thr_(cur_thread()) {
   in_rtl_ = thr_->in_rtl;
   thr_->in_rtl++;
   errno_ = errno;
 }

 ScopedInRtl::~ScopedInRtl() {
   thr_->in_rtl--;
   errno = errno_;
   CHECK_EQ(in_rtl_, thr_->in_rtl);
 }
 #else
 ScopedInRtl::ScopedInRtl() {
 }

 ScopedInRtl::~ScopedInRtl() {
 }
 #endif

 void FillProfileCallback(uptr start, uptr rss, bool file,
                          uptr *mem, uptr stats_size) {
   CHECK_EQ(7, stats_size);
   mem[6] += rss;  // total
   start >>= 40;
   if (start < 0x10)  // shadow
     mem[0] += rss;
   else if (start >= 0x20 && start < 0x30)  // compat modules
     mem[file ? 1 : 2] += rss;
   else if (start >= 0x7e)  // modules
     mem[file ? 1 : 2] += rss;
   else if (start >= 0x60 && start < 0x62)  // traces
     mem[3] += rss;
   else if (start >= 0x7d && start < 0x7e)  // heap
     mem[4] += rss;
   else  // other
     mem[5] += rss;
 }

 void WriteMemoryProfile(char *buf, uptr buf_size) {
   uptr mem[7] = {};
   __sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
   char *buf_pos = buf;
   char *buf_end = buf + buf_size;
   buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
       "RSS %zd MB: shadow:%zd file:%zd mmap:%zd trace:%zd heap:%zd other:%zd\n",
       mem[6] >> 20, mem[0] >> 20, mem[1] >> 20, mem[2] >> 20,
       mem[3] >> 20, mem[4] >> 20, mem[5] >> 20);
   struct mallinfo mi = __libc_mallinfo();
   buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
       "mallinfo: arena=%d mmap=%d fordblks=%d keepcost=%d\n",
       mi.arena >> 20, mi.hblkhd >> 20, mi.fordblks >> 20, mi.keepcost >> 20);
 }

 uptr GetRSS() {
   uptr mem[7] = {};
   __sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
   return mem[6];
 }


 void FlushShadowMemoryCallback(
     const SuspendedThreadsList &suspended_threads_list,
     void *argument) {
   FlushUnneededShadowMemory(kLinuxShadowBeg, kLinuxShadowEnd - kLinuxShadowBeg);
 }

 void FlushShadowMemory() {
   StopTheWorld(FlushShadowMemoryCallback, 0);
 }

 #ifndef TSAN_GO
 static void ProtectRange(uptr beg, uptr end) {
   ScopedInRtl in_rtl;
   CHECK_LE(beg, end);
   if (beg == end)
     return;
   if (beg != (uptr)Mprotect(beg, end - beg)) {
     Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
     Printf("FATAL: Make sure you are not using unlimited stack\n");
     Die();
   }
 }
 #endif

 #ifndef TSAN_GO
 // Mark shadow for .rodata sections with the special kShadowRodata marker.
 // Accesses to .rodata can't race, so this saves time, memory and trace space.
 static void MapRodata() {
   // First create temp file.
   const char *tmpdir = GetEnv("TMPDIR");
   if (tmpdir == 0)
     tmpdir = GetEnv("TEST_TMPDIR");
 #ifdef P_tmpdir
   if (tmpdir == 0)
     tmpdir = P_tmpdir;
 #endif
   if (tmpdir == 0)
     return;
   char filename[256];
   internal_snprintf(filename, sizeof(filename), "%s/tsan.rodata.%d",
                     tmpdir, (int)internal_getpid());
   uptr openrv = internal_open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
   if (internal_iserror(openrv))
     return;
   fd_t fd = openrv;
   // Fill the file with kShadowRodata.
   const uptr kMarkerSize = 512 * 1024 / sizeof(u64);
   InternalScopedBuffer<u64> marker(kMarkerSize);
   for (u64 *p = marker.data(); p < marker.data() + kMarkerSize; p++)
     *p = kShadowRodata;
   internal_write(fd, marker.data(), marker.size());
   // Map the file into memory.
   uptr page = internal_mmap(0, kPageSize, PROT_READ | PROT_WRITE,
                             MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
   if (internal_iserror(page)) {
     internal_close(fd);
     internal_unlink(filename);
     return;
   }
   // Map the file into shadow of .rodata sections.
   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
   uptr start, end, offset, prot;
   char name[128];
   while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name), &prot)) {
     if (name[0] != 0 && name[0] != '['
         && (prot & MemoryMappingLayout::kProtectionRead)
         && (prot & MemoryMappingLayout::kProtectionExecute)
         && !(prot & MemoryMappingLayout::kProtectionWrite)
         && IsAppMem(start)) {
       // Assume it's .rodata
       char *shadow_start = (char*)MemToShadow(start);
       char *shadow_end = (char*)MemToShadow(end);
       for (char *p = shadow_start; p < shadow_end; p += marker.size()) {
         internal_mmap(p, Min<uptr>(marker.size(), shadow_end - p),
                       PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, 0);
       }
     }
   }
   internal_close(fd);
   internal_unlink(filename);
 }

 void InitializeShadowMemory() {
   uptr shadow = (uptr)MmapFixedNoReserve(kLinuxShadowBeg,
     kLinuxShadowEnd - kLinuxShadowBeg);
   if (shadow != kLinuxShadowBeg) {
     Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
     Printf("FATAL: Make sure to compile with -fPIE and "
                "to link with -pie (%p, %p).\n", shadow, kLinuxShadowBeg);
     Die();
   }
   const uptr kClosedLowBeg  = 0x200000;
   const uptr kClosedLowEnd  = kLinuxShadowBeg - 1;
   const uptr kClosedMidBeg = kLinuxShadowEnd + 1;
   const uptr kClosedMidEnd = min(kLinuxAppMemBeg, kTraceMemBegin);
   ProtectRange(kClosedLowBeg, kClosedLowEnd);
   ProtectRange(kClosedMidBeg, kClosedMidEnd);
   DPrintf("kClosedLow   %zx-%zx (%zuGB)\n",
       kClosedLowBeg, kClosedLowEnd, (kClosedLowEnd - kClosedLowBeg) >> 30);
   DPrintf("kLinuxShadow %zx-%zx (%zuGB)\n",
       kLinuxShadowBeg, kLinuxShadowEnd,
       (kLinuxShadowEnd - kLinuxShadowBeg) >> 30);
   DPrintf("kClosedMid   %zx-%zx (%zuGB)\n",
       kClosedMidBeg, kClosedMidEnd, (kClosedMidEnd - kClosedMidBeg) >> 30);
   DPrintf("kLinuxAppMem %zx-%zx (%zuGB)\n",
       kLinuxAppMemBeg, kLinuxAppMemEnd,
       (kLinuxAppMemEnd - kLinuxAppMemBeg) >> 30);
   DPrintf("stack        %zx\n", (uptr)&shadow);

   MapRodata();
 }
 #endif

 static uptr g_data_start;
 static uptr g_data_end;

 #ifndef TSAN_GO
 static void CheckPIE() {
   // Ensure that the binary is indeed compiled with -pie.
   MemoryMappingLayout proc_maps(true);
   uptr start, end;
   if (proc_maps.Next(&start, &end,
                      /*offset*/0, /*filename*/0, /*filename_size*/0,
                      /*protection*/0)) {
     if ((u64)start < kLinuxAppMemBeg) {
       Printf("FATAL: ThreadSanitizer can not mmap the shadow memory ("
              "something is mapped at 0x%zx < 0x%zx)\n",
              start, kLinuxAppMemBeg);
       Printf("FATAL: Make sure to compile with -fPIE"
              " and to link with -pie.\n");
       Die();
     }
   }
 }

 static void InitDataSeg() {
   MemoryMappingLayout proc_maps(true);
   uptr start, end, offset;
   char name[128];
   bool prev_is_data = false;
   while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name),
                         /*protection*/ 0)) {
     DPrintf("%p-%p %p %s\n", start, end, offset, name);
     bool is_data = offset != 0 && name[0] != 0;
     // BSS may get merged with [heap] in /proc/self/maps. This is not very
     // reliable.
     bool is_bss = offset == 0 &&
       (name[0] == 0 || internal_strcmp(name, "[heap]") == 0) && prev_is_data;
     if (g_data_start == 0 && is_data)
       g_data_start = start;
     if (is_bss)
       g_data_end = end;
     prev_is_data = is_data;
   }
   DPrintf("guessed data_start=%p data_end=%p\n",  g_data_start, g_data_end);
   CHECK_LT(g_data_start, g_data_end);
   CHECK_GE((uptr)&g_data_start, g_data_start);
   CHECK_LT((uptr)&g_data_start, g_data_end);
 }

 #endif  // #ifndef TSAN_GO

 static rlim_t getlim(int res) {
   rlimit rlim;
   CHECK_EQ(0, getrlimit(res, &rlim));
   return rlim.rlim_cur;
 }

 static void setlim(int res, rlim_t lim) {
   // The following magic is to prevent clang from replacing it with memset.
   volatile rlimit rlim;
   rlim.rlim_cur = lim;
   rlim.rlim_max = lim;
   setrlimit(res, (rlimit*)&rlim);
 }

 const char *InitializePlatform() {
   void *p = 0;
   if (sizeof(p) == 8) {
     // Disable core dumps, dumping of 16TB usually takes a bit long.
     setlim(RLIMIT_CORE, 0);
   }

   // Go maps shadow memory lazily and works fine with limited address space.
   // Unlimited stack is not a problem as well, because the executable
   // is not compiled with -pie.
   if (kCppMode) {
     bool reexec = false;
     // TSan doesn't play well with unlimited stack size (as stack
     // overlaps with shadow memory). If we detect unlimited stack size,
     // we re-exec the program with limited stack size as a best effort.
     if (getlim(RLIMIT_STACK) == (rlim_t)-1) {
       const uptr kMaxStackSize = 32 * 1024 * 1024;
       Report("WARNING: Program is run with unlimited stack size, which "
              "wouldn't work with ThreadSanitizer.\n");
       Report("Re-execing with stack size limited to %zd bytes.\n",
              kMaxStackSize);
       SetStackSizeLimitInBytes(kMaxStackSize);
       reexec = true;
     }

     if (getlim(RLIMIT_AS) != (rlim_t)-1) {
       Report("WARNING: Program is run with limited virtual address space,"
              " which wouldn't work with ThreadSanitizer.\n");
       Report("Re-execing with unlimited virtual address space.\n");
       setlim(RLIMIT_AS, -1);
       reexec = true;
     }
     if (reexec)
       ReExec();
   }

 #ifndef TSAN_GO
   CheckPIE();
   InitTlsSize();
   InitDataSeg();
 #endif
   return GetEnv(kTsanOptionsEnv);
 }

 bool IsGlobalVar(uptr addr) {
   return g_data_start && addr >= g_data_start && addr < g_data_end;
 }

 #ifndef TSAN_GO
 // Extract file descriptors passed to glibc internal __res_iclose function.
 // This is required to properly "close" the fds, because we do not see internal
 // closes within glibc. The code is a pure hack.
 int ExtractResolvFDs(void *state, int *fds, int nfd) {
   int cnt = 0;
   __res_state *statp = (__res_state*)state;
   for (int i = 0; i < MAXNS && cnt < nfd; i++) {
     if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
       fds[cnt++] = statp->_u._ext.nssocks[i];
   }
   return cnt;
 }

 // Extract file descriptors passed via UNIX domain sockets.
 // This is requried to properly handle "open" of these fds.
 // see 'man recvmsg' and 'man 3 cmsg'.
 int ExtractRecvmsgFDs(void *msgp, int *fds, int nfd) {
   int res = 0;
   msghdr *msg = (msghdr*)msgp;
   struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
   for (; cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
     if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
       continue;
     int n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(fds[0]);
     for (int i = 0; i < n; i++) {
       fds[res++] = ((int*)CMSG_DATA(cmsg))[i];
       if (res == nfd)
         return res;
     }
   }
   return res;
 }
 #endif


 }  // namespace __tsan

 #endif  // SANITIZER_LINUX
	//===-- tsan_platform_linux.cc --------------------------------------------===//
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file is a part of ThreadSanitizer (TSan), a race detector.
	//
	// Linux-specific code.
	//===----------------------------------------------------------------------===//


	#include "sanitizer_common/sanitizer_platform.h"
	#if SANITIZER_LINUX

	#include "sanitizer_common/sanitizer_common.h"
	#include "sanitizer_common/sanitizer_libc.h"
	#include "sanitizer_common/sanitizer_procmaps.h"
	#include "sanitizer_common/sanitizer_stoptheworld.h"
	#include "tsan_platform.h"
	#include "tsan_rtl.h"
	#include "tsan_flags.h"

	#include <fcntl.h>
	#include <pthread.h>
	#include <signal.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <stdarg.h>
	#include <sys/mman.h>
	#include <sys/prctl.h>
	#include <sys/syscall.h>
	#include <sys/socket.h>
	#include <sys/time.h>
	#include <sys/types.h>
	#include <sys/resource.h>
	#include <sys/stat.h>
	#include <unistd.h>
	#include <errno.h>
	#include <sched.h>
	#include <dlfcn.h>
	#define __need_res_state
	#include <resolv.h>
	#include <malloc.h>

	#ifdef sa_handler
	# undef sa_handler
	#endif

	#ifdef sa_sigaction
	# undef sa_sigaction
	#endif

	extern "C" struct mallinfo __libc_mallinfo();

	namespace __tsan {

	const uptr kPageSize = 4096;

	#ifndef TSAN_GO
	ScopedInRtl::ScopedInRtl()
	: thr_(cur_thread()) {
	in_rtl_ = thr_->in_rtl;
	thr_->in_rtl++;
	errno_ = errno;
	}

	ScopedInRtl::~ScopedInRtl() {
	thr_->in_rtl--;
	errno = errno_;
	CHECK_EQ(in_rtl_, thr_->in_rtl);
	}
	#else
	ScopedInRtl::ScopedInRtl() {
	}

	ScopedInRtl::~ScopedInRtl() {
	}
	#endif

	void FillProfileCallback(uptr start, uptr rss, bool file,
	uptr *mem, uptr stats_size) {
	CHECK_EQ(7, stats_size);
	mem[6] += rss; // total
	start >>= 40;
	if (start < 0x10) // shadow
	mem[0] += rss;
	else if (start >= 0x20 && start < 0x30) // compat modules
	mem[file ? 1 : 2] += rss;
	else if (start >= 0x7e) // modules
	mem[file ? 1 : 2] += rss;
	else if (start >= 0x60 && start < 0x62) // traces
	mem[3] += rss;
	else if (start >= 0x7d && start < 0x7e) // heap
	mem[4] += rss;
	else // other
	mem[5] += rss;
	}

	void WriteMemoryProfile(char *buf, uptr buf_size) {
	uptr mem[7] = {};
	__sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
	char *buf_pos = buf;
	char *buf_end = buf + buf_size;
	buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
	"RSS %zd MB: shadow:%zd file:%zd mmap:%zd trace:%zd heap:%zd other:%zd\n",
	mem[6] >> 20, mem[0] >> 20, mem[1] >> 20, mem[2] >> 20,
	mem[3] >> 20, mem[4] >> 20, mem[5] >> 20);
	struct mallinfo mi = __libc_mallinfo();
	buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
	"mallinfo: arena=%d mmap=%d fordblks=%d keepcost=%d\n",
	mi.arena >> 20, mi.hblkhd >> 20, mi.fordblks >> 20, mi.keepcost >> 20);
	}

	uptr GetRSS() {
	uptr mem[7] = {};
	__sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
	return mem[6];
	}


	void FlushShadowMemoryCallback(
	const SuspendedThreadsList &suspended_threads_list,
	void *argument) {
	FlushUnneededShadowMemory(kLinuxShadowBeg, kLinuxShadowEnd - kLinuxShadowBeg);
	}

	void FlushShadowMemory() {
	StopTheWorld(FlushShadowMemoryCallback, 0);
	}

	#ifndef TSAN_GO
	static void ProtectRange(uptr beg, uptr end) {
	ScopedInRtl in_rtl;
	CHECK_LE(beg, end);
	if (beg == end)
	return;
	if (beg != (uptr)Mprotect(beg, end - beg)) {
	Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
	Printf("FATAL: Make sure you are not using unlimited stack\n");
	Die();
	}
	}
	#endif

	#ifndef TSAN_GO
	// Mark shadow for .rodata sections with the special kShadowRodata marker.
	// Accesses to .rodata can't race, so this saves time, memory and trace space.
	static void MapRodata() {
	// First create temp file.
	const char *tmpdir = GetEnv("TMPDIR");
	if (tmpdir == 0)
	tmpdir = GetEnv("TEST_TMPDIR");
	#ifdef P_tmpdir
	if (tmpdir == 0)
	tmpdir = P_tmpdir;
	#endif
	if (tmpdir == 0)
	return;
	char filename[256];
	internal_snprintf(filename, sizeof(filename), "%s/tsan.rodata.%d",
	tmpdir, (int)internal_getpid());
	uptr openrv = internal_open(filename, O_RDWR \| O_CREAT \| O_EXCL, 0600);
	if (internal_iserror(openrv))
	return;
	fd_t fd = openrv;
	// Fill the file with kShadowRodata.
	const uptr kMarkerSize = 512 * 1024 / sizeof(u64);
	InternalScopedBuffer<u64> marker(kMarkerSize);
	for (u64 *p = marker.data(); p < marker.data() + kMarkerSize; p++)
	*p = kShadowRodata;
	internal_write(fd, marker.data(), marker.size());
	// Map the file into memory.
	uptr page = internal_mmap(0, kPageSize, PROT_READ \| PROT_WRITE,
	MAP_PRIVATE \| MAP_ANONYMOUS, fd, 0);
	if (internal_iserror(page)) {
	internal_close(fd);
	internal_unlink(filename);
	return;
	}
	// Map the file into shadow of .rodata sections.
	MemoryMappingLayout proc_maps(/cache_enabled/true);
	uptr start, end, offset, prot;
	char name[128];
	while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name), &prot)) {
	if (name[0] != 0 && name[0] != '['
	&& (prot & MemoryMappingLayout::kProtectionRead)
	&& (prot & MemoryMappingLayout::kProtectionExecute)
	&& !(prot & MemoryMappingLayout::kProtectionWrite)
	&& IsAppMem(start)) {
	// Assume it's .rodata
	char shadow_start = (char)MemToShadow(start);
	char shadow_end = (char)MemToShadow(end);
	for (char *p = shadow_start; p < shadow_end; p += marker.size()) {
	internal_mmap(p, Min<uptr>(marker.size(), shadow_end - p),
	PROT_READ, MAP_PRIVATE \| MAP_FIXED, fd, 0);
	}
	}
	}
	internal_close(fd);
	internal_unlink(filename);
	}

	void InitializeShadowMemory() {
	uptr shadow = (uptr)MmapFixedNoReserve(kLinuxShadowBeg,
	kLinuxShadowEnd - kLinuxShadowBeg);
	if (shadow != kLinuxShadowBeg) {
	Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
	Printf("FATAL: Make sure to compile with -fPIE and "
	"to link with -pie (%p, %p).\n", shadow, kLinuxShadowBeg);
	Die();
	}
	const uptr kClosedLowBeg = 0x200000;
	const uptr kClosedLowEnd = kLinuxShadowBeg - 1;
	const uptr kClosedMidBeg = kLinuxShadowEnd + 1;
	const uptr kClosedMidEnd = min(kLinuxAppMemBeg, kTraceMemBegin);
	ProtectRange(kClosedLowBeg, kClosedLowEnd);
	ProtectRange(kClosedMidBeg, kClosedMidEnd);
	DPrintf("kClosedLow %zx-%zx (%zuGB)\n",
	kClosedLowBeg, kClosedLowEnd, (kClosedLowEnd - kClosedLowBeg) >> 30);
	DPrintf("kLinuxShadow %zx-%zx (%zuGB)\n",
	kLinuxShadowBeg, kLinuxShadowEnd,
	(kLinuxShadowEnd - kLinuxShadowBeg) >> 30);
	DPrintf("kClosedMid %zx-%zx (%zuGB)\n",
	kClosedMidBeg, kClosedMidEnd, (kClosedMidEnd - kClosedMidBeg) >> 30);
	DPrintf("kLinuxAppMem %zx-%zx (%zuGB)\n",
	kLinuxAppMemBeg, kLinuxAppMemEnd,
	(kLinuxAppMemEnd - kLinuxAppMemBeg) >> 30);
	DPrintf("stack %zx\n", (uptr)&shadow);

	MapRodata();
	}
	#endif

	static uptr g_data_start;
	static uptr g_data_end;

	#ifndef TSAN_GO
	static void CheckPIE() {
	// Ensure that the binary is indeed compiled with -pie.
	MemoryMappingLayout proc_maps(true);
	uptr start, end;
	if (proc_maps.Next(&start, &end,
	/offset/0, /filename/0, /filename_size/0,
	/protection/0)) {
	if ((u64)start < kLinuxAppMemBeg) {
	Printf("FATAL: ThreadSanitizer can not mmap the shadow memory ("
	"something is mapped at 0x%zx < 0x%zx)\n",
	start, kLinuxAppMemBeg);
	Printf("FATAL: Make sure to compile with -fPIE"
	" and to link with -pie.\n");
	Die();
	}
	}
	}

	static void InitDataSeg() {
	MemoryMappingLayout proc_maps(true);
	uptr start, end, offset;
	char name[128];
	bool prev_is_data = false;
	while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name),
	/protection/ 0)) {
	DPrintf("%p-%p %p %s\n", start, end, offset, name);
	bool is_data = offset != 0 && name[0] != 0;
	// BSS may get merged with [heap] in /proc/self/maps. This is not very
	// reliable.
	bool is_bss = offset == 0 &&
	(name[0] == 0 \|\| internal_strcmp(name, "[heap]") == 0) && prev_is_data;
	if (g_data_start == 0 && is_data)
	g_data_start = start;
	if (is_bss)
	g_data_end = end;
	prev_is_data = is_data;
	}
	DPrintf("guessed data_start=%p data_end=%p\n", g_data_start, g_data_end);
	CHECK_LT(g_data_start, g_data_end);
	CHECK_GE((uptr)&g_data_start, g_data_start);
	CHECK_LT((uptr)&g_data_start, g_data_end);
	}

	#endif // #ifndef TSAN_GO

	static rlim_t getlim(int res) {
	rlimit rlim;
	CHECK_EQ(0, getrlimit(res, &rlim));
	return rlim.rlim_cur;
	}

	static void setlim(int res, rlim_t lim) {
	// The following magic is to prevent clang from replacing it with memset.
	volatile rlimit rlim;
	rlim.rlim_cur = lim;
	rlim.rlim_max = lim;
	setrlimit(res, (rlimit*)&rlim);
	}

	const char *InitializePlatform() {
	void *p = 0;
	if (sizeof(p) == 8) {
	// Disable core dumps, dumping of 16TB usually takes a bit long.
	setlim(RLIMIT_CORE, 0);
	}

	// Go maps shadow memory lazily and works fine with limited address space.
	// Unlimited stack is not a problem as well, because the executable
	// is not compiled with -pie.
	if (kCppMode) {
	bool reexec = false;
	// TSan doesn't play well with unlimited stack size (as stack
	// overlaps with shadow memory). If we detect unlimited stack size,
	// we re-exec the program with limited stack size as a best effort.
	if (getlim(RLIMIT_STACK) == (rlim_t)-1) {
	const uptr kMaxStackSize = 32 * 1024 * 1024;
	Report("WARNING: Program is run with unlimited stack size, which "
	"wouldn't work with ThreadSanitizer.\n");
	Report("Re-execing with stack size limited to %zd bytes.\n",
	kMaxStackSize);
	SetStackSizeLimitInBytes(kMaxStackSize);
	reexec = true;
	}

	if (getlim(RLIMIT_AS) != (rlim_t)-1) {
	Report("WARNING: Program is run with limited virtual address space,"
	" which wouldn't work with ThreadSanitizer.\n");
	Report("Re-execing with unlimited virtual address space.\n");
	setlim(RLIMIT_AS, -1);
	reexec = true;
	}
	if (reexec)
	ReExec();
	}

	#ifndef TSAN_GO
	CheckPIE();
	InitTlsSize();
	InitDataSeg();
	#endif
	return GetEnv(kTsanOptionsEnv);
	}

	bool IsGlobalVar(uptr addr) {
	return g_data_start && addr >= g_data_start && addr < g_data_end;
	}

	#ifndef TSAN_GO
	// Extract file descriptors passed to glibc internal __res_iclose function.
	// This is required to properly "close" the fds, because we do not see internal
	// closes within glibc. The code is a pure hack.
	int ExtractResolvFDs(void state, int fds, int nfd) {
	int cnt = 0;
	__res_state statp = (__res_state)state;
	for (int i = 0; i < MAXNS && cnt < nfd; i++) {
	if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
	fds[cnt++] = statp->_u._ext.nssocks[i];
	}
	return cnt;
	}

	// Extract file descriptors passed via UNIX domain sockets.
	// This is requried to properly handle "open" of these fds.
	// see 'man recvmsg' and 'man 3 cmsg'.
	int ExtractRecvmsgFDs(void msgp, int fds, int nfd) {
	int res = 0;
	msghdr msg = (msghdr)msgp;
	struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
	for (; cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
	if (cmsg->cmsg_level != SOL_SOCKET \|\| cmsg->cmsg_type != SCM_RIGHTS)
	continue;
	int n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(fds[0]);
	for (int i = 0; i < n; i++) {
	fds[res++] = ((int*)CMSG_DATA(cmsg))[i];
	if (res == nfd)
	return res;
	}
	}
	return res;
	}
	#endif


	} // namespace __tsan

	#endif // SANITIZER_LINUX