1//===-- tsan_platform_linux.cc --------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of ThreadSanitizer (TSan), a race detector.
11//
12// Linux-specific code.
13//===----------------------------------------------------------------------===//
14
15
16#include "sanitizer_common/sanitizer_platform.h"
17#if SANITIZER_LINUX
18
19#include "sanitizer_common/sanitizer_common.h"
20#include "sanitizer_common/sanitizer_libc.h"
21#include "sanitizer_common/sanitizer_procmaps.h"
22#include "tsan_platform.h"
23#include "tsan_rtl.h"
24#include "tsan_flags.h"
25
26#include <fcntl.h>
27#include <pthread.h>
28#include <signal.h>
29#include <stdio.h>
30#include <stdlib.h>
31#include <string.h>
32#include <stdarg.h>
33#include <sys/mman.h>
34#include <sys/prctl.h>
35#include <sys/syscall.h>
36#include <sys/time.h>
37#include <sys/types.h>
38#include <sys/resource.h>
39#include <sys/stat.h>
40#include <unistd.h>
41#include <errno.h>
42#include <sched.h>
43#include <dlfcn.h>
44#define __need_res_state
45#include <resolv.h>
46#include <malloc.h>
47
48extern "C" struct mallinfo __libc_mallinfo();
49
50namespace __tsan {
51
52const uptr kPageSize = 4096;
53
54#ifndef TSAN_GO
55ScopedInRtl::ScopedInRtl()
56    : thr_(cur_thread()) {
57  in_rtl_ = thr_->in_rtl;
58  thr_->in_rtl++;
59  errno_ = errno;
60}
61
62ScopedInRtl::~ScopedInRtl() {
63  thr_->in_rtl--;
64  errno = errno_;
65  CHECK_EQ(in_rtl_, thr_->in_rtl);
66}
67#else
68ScopedInRtl::ScopedInRtl() {
69}
70
71ScopedInRtl::~ScopedInRtl() {
72}
73#endif
74
75static bool ishex(char c) {
76  return (c >= '0' && c <= '9')
77      || (c >= 'a' && c <= 'f');
78}
79
80static uptr readhex(const char *p) {
81  uptr v = 0;
82  for (; ishex(p[0]); p++) {
83    if (p[0] >= '0' && p[0] <= '9')
84      v = v * 16 + p[0] - '0';
85    else
86      v = v * 16 + p[0] - 'a' + 10;
87  }
88  return v;
89}
90
91static uptr readdec(const char *p) {
92  uptr v = 0;
93  for (; p[0] >= '0' && p[0] <= '9' ; p++)
94    v = v * 10 + p[0] - '0';
95  return v;
96}
97
98void WriteMemoryProfile(char *buf, uptr buf_size) {
99  char *smaps = 0;
100  uptr smaps_cap = 0;
101  uptr smaps_len = ReadFileToBuffer("/proc/self/smaps",
102      &smaps, &smaps_cap, 64<<20);
103  uptr mem[6] = {};
104  uptr total = 0;
105  uptr start = 0;
106  bool file = false;
107  const char *pos = smaps;
108  while (pos < smaps + smaps_len) {
109    if (ishex(pos[0])) {
110      start = readhex(pos);
111      for (; *pos != '/' && *pos > '\n'; pos++) {}
112      file = *pos == '/';
113    } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
114      for (; *pos < '0' || *pos > '9'; pos++) {}
115      uptr rss = readdec(pos) * 1024;
116      total += rss;
117      start >>= 40;
118      if (start < 0x10)  // shadow
119        mem[0] += rss;
120      else if (start >= 0x20 && start < 0x30)  // compat modules
121        mem[file ? 1 : 2] += rss;
122      else if (start >= 0x7e)  // modules
123        mem[file ? 1 : 2] += rss;
124      else if (start >= 0x60 && start < 0x62)  // traces
125        mem[3] += rss;
126      else if (start >= 0x7d && start < 0x7e)  // heap
127        mem[4] += rss;
128      else  // other
129        mem[5] += rss;
130    }
131    while (*pos++ != '\n') {}
132  }
133  UnmapOrDie(smaps, smaps_cap);
134  char *buf_pos = buf;
135  char *buf_end = buf + buf_size;
136  buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
137      "RSS %zd MB: shadow:%zd file:%zd mmap:%zd trace:%zd heap:%zd other:%zd\n",
138      total >> 20, mem[0] >> 20, mem[1] >> 20, mem[2] >> 20,
139      mem[3] >> 20, mem[4] >> 20, mem[5] >> 20);
140  struct mallinfo mi = __libc_mallinfo();
141  buf_pos += internal_snprintf(buf_pos, buf_end - buf_pos,
142      "mallinfo: arena=%d mmap=%d fordblks=%d keepcost=%d\n",
143      mi.arena >> 20, mi.hblkhd >> 20, mi.fordblks >> 20, mi.keepcost >> 20);
144}
145
146void FlushShadowMemory() {
147  FlushUnneededShadowMemory(kLinuxShadowBeg, kLinuxShadowEnd - kLinuxShadowBeg);
148}
149
150#ifndef TSAN_GO
151static void ProtectRange(uptr beg, uptr end) {
152  ScopedInRtl in_rtl;
153  CHECK_LE(beg, end);
154  if (beg == end)
155    return;
156  if (beg != (uptr)Mprotect(beg, end - beg)) {
157    Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
158    Printf("FATAL: Make sure you are not using unlimited stack\n");
159    Die();
160  }
161}
162#endif
163
164#ifndef TSAN_GO
165// Mark shadow for .rodata sections with the special kShadowRodata marker.
166// Accesses to .rodata can't race, so this saves time, memory and trace space.
167static void MapRodata() {
168  // First create temp file.
169  const char *tmpdir = GetEnv("TMPDIR");
170  if (tmpdir == 0)
171    tmpdir = GetEnv("TEST_TMPDIR");
172#ifdef P_tmpdir
173  if (tmpdir == 0)
174    tmpdir = P_tmpdir;
175#endif
176  if (tmpdir == 0)
177    return;
178  char filename[256];
179  internal_snprintf(filename, sizeof(filename), "%s/tsan.rodata.%d",
180                    tmpdir, (int)internal_getpid());
181  uptr openrv = internal_open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
182  if (internal_iserror(openrv))
183    return;
184  fd_t fd = openrv;
185  // Fill the file with kShadowRodata.
186  const uptr kMarkerSize = 512 * 1024 / sizeof(u64);
187  InternalScopedBuffer<u64> marker(kMarkerSize);
188  for (u64 *p = marker.data(); p < marker.data() + kMarkerSize; p++)
189    *p = kShadowRodata;
190  internal_write(fd, marker.data(), marker.size());
191  // Map the file into memory.
192  uptr page = internal_mmap(0, kPageSize, PROT_READ | PROT_WRITE,
193                            MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
194  if (internal_iserror(page)) {
195    internal_close(fd);
196    internal_unlink(filename);
197    return;
198  }
199  // Map the file into shadow of .rodata sections.
200  MemoryMappingLayout proc_maps(/*cache_enabled*/true);
201  uptr start, end, offset, prot;
202  char name[128];
203  while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name), &prot)) {
204    if (name[0] != 0 && name[0] != '['
205        && (prot & MemoryMappingLayout::kProtectionRead)
206        && (prot & MemoryMappingLayout::kProtectionExecute)
207        && !(prot & MemoryMappingLayout::kProtectionWrite)
208        && IsAppMem(start)) {
209      // Assume it's .rodata
210      char *shadow_start = (char*)MemToShadow(start);
211      char *shadow_end = (char*)MemToShadow(end);
212      for (char *p = shadow_start; p < shadow_end; p += marker.size()) {
213        internal_mmap(p, Min<uptr>(marker.size(), shadow_end - p),
214                      PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, 0);
215      }
216    }
217  }
218  internal_close(fd);
219  internal_unlink(filename);
220}
221
222void InitializeShadowMemory() {
223  uptr shadow = (uptr)MmapFixedNoReserve(kLinuxShadowBeg,
224    kLinuxShadowEnd - kLinuxShadowBeg);
225  if (shadow != kLinuxShadowBeg) {
226    Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
227    Printf("FATAL: Make sure to compile with -fPIE and "
228               "to link with -pie (%p, %p).\n", shadow, kLinuxShadowBeg);
229    Die();
230  }
231  const uptr kClosedLowBeg  = 0x200000;
232  const uptr kClosedLowEnd  = kLinuxShadowBeg - 1;
233  const uptr kClosedMidBeg = kLinuxShadowEnd + 1;
234  const uptr kClosedMidEnd = min(kLinuxAppMemBeg, kTraceMemBegin);
235  ProtectRange(kClosedLowBeg, kClosedLowEnd);
236  ProtectRange(kClosedMidBeg, kClosedMidEnd);
237  DPrintf("kClosedLow   %zx-%zx (%zuGB)\n",
238      kClosedLowBeg, kClosedLowEnd, (kClosedLowEnd - kClosedLowBeg) >> 30);
239  DPrintf("kLinuxShadow %zx-%zx (%zuGB)\n",
240      kLinuxShadowBeg, kLinuxShadowEnd,
241      (kLinuxShadowEnd - kLinuxShadowBeg) >> 30);
242  DPrintf("kClosedMid   %zx-%zx (%zuGB)\n",
243      kClosedMidBeg, kClosedMidEnd, (kClosedMidEnd - kClosedMidBeg) >> 30);
244  DPrintf("kLinuxAppMem %zx-%zx (%zuGB)\n",
245      kLinuxAppMemBeg, kLinuxAppMemEnd,
246      (kLinuxAppMemEnd - kLinuxAppMemBeg) >> 30);
247  DPrintf("stack        %zx\n", (uptr)&shadow);
248
249  MapRodata();
250}
251#endif
252
253static uptr g_data_start;
254static uptr g_data_end;
255
256#ifndef TSAN_GO
257static void CheckPIE() {
258  // Ensure that the binary is indeed compiled with -pie.
259  MemoryMappingLayout proc_maps(true);
260  uptr start, end;
261  if (proc_maps.Next(&start, &end,
262                     /*offset*/0, /*filename*/0, /*filename_size*/0,
263                     /*protection*/0)) {
264    if ((u64)start < kLinuxAppMemBeg) {
265      Printf("FATAL: ThreadSanitizer can not mmap the shadow memory ("
266             "something is mapped at 0x%zx < 0x%zx)\n",
267             start, kLinuxAppMemBeg);
268      Printf("FATAL: Make sure to compile with -fPIE"
269             " and to link with -pie.\n");
270      Die();
271    }
272  }
273}
274
275static void InitDataSeg() {
276  MemoryMappingLayout proc_maps(true);
277  uptr start, end, offset;
278  char name[128];
279  bool prev_is_data = false;
280  while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name),
281                        /*protection*/ 0)) {
282    DPrintf("%p-%p %p %s\n", start, end, offset, name);
283    bool is_data = offset != 0 && name[0] != 0;
284    // BSS may get merged with [heap] in /proc/self/maps. This is not very
285    // reliable.
286    bool is_bss = offset == 0 &&
287      (name[0] == 0 || internal_strcmp(name, "[heap]") == 0) && prev_is_data;
288    if (g_data_start == 0 && is_data)
289      g_data_start = start;
290    if (is_bss)
291      g_data_end = end;
292    prev_is_data = is_data;
293  }
294  DPrintf("guessed data_start=%p data_end=%p\n",  g_data_start, g_data_end);
295  CHECK_LT(g_data_start, g_data_end);
296  CHECK_GE((uptr)&g_data_start, g_data_start);
297  CHECK_LT((uptr)&g_data_start, g_data_end);
298}
299
300#endif  // #ifndef TSAN_GO
301
302static rlim_t getlim(int res) {
303  rlimit rlim;
304  CHECK_EQ(0, getrlimit(res, &rlim));
305  return rlim.rlim_cur;
306}
307
308static void setlim(int res, rlim_t lim) {
309  // The following magic is to prevent clang from replacing it with memset.
310  volatile rlimit rlim;
311  rlim.rlim_cur = lim;
312  rlim.rlim_max = lim;
313  setrlimit(res, (rlimit*)&rlim);
314}
315
316const char *InitializePlatform() {
317  void *p = 0;
318  if (sizeof(p) == 8) {
319    // Disable core dumps, dumping of 16TB usually takes a bit long.
320    setlim(RLIMIT_CORE, 0);
321  }
322
323  // Go maps shadow memory lazily and works fine with limited address space.
324  // Unlimited stack is not a problem as well, because the executable
325  // is not compiled with -pie.
326  if (kCppMode) {
327    bool reexec = false;
328    // TSan doesn't play well with unlimited stack size (as stack
329    // overlaps with shadow memory). If we detect unlimited stack size,
330    // we re-exec the program with limited stack size as a best effort.
331    if (getlim(RLIMIT_STACK) == (rlim_t)-1) {
332      const uptr kMaxStackSize = 32 * 1024 * 1024;
333      Report("WARNING: Program is run with unlimited stack size, which "
334             "wouldn't work with ThreadSanitizer.\n");
335      Report("Re-execing with stack size limited to %zd bytes.\n",
336             kMaxStackSize);
337      SetStackSizeLimitInBytes(kMaxStackSize);
338      reexec = true;
339    }
340
341    if (getlim(RLIMIT_AS) != (rlim_t)-1) {
342      Report("WARNING: Program is run with limited virtual address space,"
343             " which wouldn't work with ThreadSanitizer.\n");
344      Report("Re-execing with unlimited virtual address space.\n");
345      setlim(RLIMIT_AS, -1);
346      reexec = true;
347    }
348    if (reexec)
349      ReExec();
350  }
351
352#ifndef TSAN_GO
353  CheckPIE();
354  InitTlsSize();
355  InitDataSeg();
356#endif
357  return GetEnv(kTsanOptionsEnv);
358}
359
360bool IsGlobalVar(uptr addr) {
361  return g_data_start && addr >= g_data_start && addr < g_data_end;
362}
363
364#ifndef TSAN_GO
365int ExtractResolvFDs(void *state, int *fds, int nfd) {
366  int cnt = 0;
367  __res_state *statp = (__res_state*)state;
368  for (int i = 0; i < MAXNS && cnt < nfd; i++) {
369    if (statp->_u._ext.nsaddrs[i] && statp->_u._ext.nssocks[i] != -1)
370      fds[cnt++] = statp->_u._ext.nssocks[i];
371  }
372  return cnt;
373}
374#endif
375
376
377}  // namespace __tsan
378
379#endif  // SANITIZER_LINUX
380