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- and FreeBSD-specific code.
13 //===----------------------------------------------------------------------===//
14 
15 
16 #include "sanitizer_common/sanitizer_platform.h"
17 #if SANITIZER_LINUX || SANITIZER_FREEBSD
18 
19 #include "sanitizer_common/sanitizer_common.h"
20 #include "sanitizer_common/sanitizer_libc.h"
21 #include "sanitizer_common/sanitizer_posix.h"
22 #include "sanitizer_common/sanitizer_procmaps.h"
23 #include "sanitizer_common/sanitizer_stoptheworld.h"
24 #include "sanitizer_common/sanitizer_stackdepot.h"
25 #include "tsan_platform.h"
26 #include "tsan_rtl.h"
27 #include "tsan_flags.h"
28 
29 #include <fcntl.h>
30 #include <pthread.h>
31 #include <signal.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <stdarg.h>
36 #include <sys/mman.h>
37 #include <sys/syscall.h>
38 #include <sys/socket.h>
39 #include <sys/time.h>
40 #include <sys/types.h>
41 #include <sys/resource.h>
42 #include <sys/stat.h>
43 #include <unistd.h>
44 #include <errno.h>
45 #include <sched.h>
46 #include <dlfcn.h>
47 #if SANITIZER_LINUX
48 #define __need_res_state
49 #include <resolv.h>
50 #endif
51 
52 #ifdef sa_handler
53 # undef sa_handler
54 #endif
55 
56 #ifdef sa_sigaction
57 # undef sa_sigaction
58 #endif
59 
60 #if SANITIZER_FREEBSD
61 extern "C" void *__libc_stack_end;
62 void *__libc_stack_end = 0;
63 #endif
64 
65 namespace __tsan {
66 
67 static uptr g_data_start;
68 static uptr g_data_end;
69 
70 enum {
71   MemTotal  = 0,
72   MemShadow = 1,
73   MemMeta   = 2,
74   MemFile   = 3,
75   MemMmap   = 4,
76   MemTrace  = 5,
77   MemHeap   = 6,
78   MemOther  = 7,
79   MemCount  = 8,
80 };
81 
FillProfileCallback(uptr p,uptr rss,bool file,uptr * mem,uptr stats_size)82 void FillProfileCallback(uptr p, uptr rss, bool file,
83                          uptr *mem, uptr stats_size) {
84   mem[MemTotal] += rss;
85   if (p >= kShadowBeg && p < kShadowEnd)
86     mem[MemShadow] += rss;
87   else if (p >= kMetaShadowBeg && p < kMetaShadowEnd)
88     mem[MemMeta] += rss;
89 #ifndef SANITIZER_GO
90   else if (p >= kHeapMemBeg && p < kHeapMemEnd)
91     mem[MemHeap] += rss;
92   else if (p >= kLoAppMemBeg && p < kLoAppMemEnd)
93     mem[file ? MemFile : MemMmap] += rss;
94   else if (p >= kHiAppMemBeg && p < kHiAppMemEnd)
95     mem[file ? MemFile : MemMmap] += rss;
96 #else
97   else if (p >= kAppMemBeg && p < kAppMemEnd)
98     mem[file ? MemFile : MemMmap] += rss;
99 #endif
100   else if (p >= kTraceMemBeg && p < kTraceMemEnd)
101     mem[MemTrace] += rss;
102   else
103     mem[MemOther] += rss;
104 }
105 
WriteMemoryProfile(char * buf,uptr buf_size,uptr nthread,uptr nlive)106 void WriteMemoryProfile(char *buf, uptr buf_size, uptr nthread, uptr nlive) {
107   uptr mem[MemCount] = {};
108   __sanitizer::GetMemoryProfile(FillProfileCallback, mem, 7);
109   StackDepotStats *stacks = StackDepotGetStats();
110   internal_snprintf(buf, buf_size,
111       "RSS %zd MB: shadow:%zd meta:%zd file:%zd mmap:%zd"
112       " trace:%zd heap:%zd other:%zd stacks=%zd[%zd] nthr=%zd/%zd\n",
113       mem[MemTotal] >> 20, mem[MemShadow] >> 20, mem[MemMeta] >> 20,
114       mem[MemFile] >> 20, mem[MemMmap] >> 20, mem[MemTrace] >> 20,
115       mem[MemHeap] >> 20, mem[MemOther] >> 20,
116       stacks->allocated >> 20, stacks->n_uniq_ids,
117       nlive, nthread);
118 }
119 
120 #if SANITIZER_LINUX
FlushShadowMemoryCallback(const SuspendedThreadsList & suspended_threads_list,void * argument)121 void FlushShadowMemoryCallback(
122     const SuspendedThreadsList &suspended_threads_list,
123     void *argument) {
124   FlushUnneededShadowMemory(kShadowBeg, kShadowEnd - kShadowBeg);
125 }
126 #endif
127 
FlushShadowMemory()128 void FlushShadowMemory() {
129 #if SANITIZER_LINUX
130   StopTheWorld(FlushShadowMemoryCallback, 0);
131 #endif
132 }
133 
134 #ifndef SANITIZER_GO
ProtectRange(uptr beg,uptr end)135 static void ProtectRange(uptr beg, uptr end) {
136   CHECK_LE(beg, end);
137   if (beg == end)
138     return;
139   if (beg != (uptr)MmapNoAccess(beg, end - beg)) {
140     Printf("FATAL: ThreadSanitizer can not protect [%zx,%zx]\n", beg, end);
141     Printf("FATAL: Make sure you are not using unlimited stack\n");
142     Die();
143   }
144 }
145 
146 // Mark shadow for .rodata sections with the special kShadowRodata marker.
147 // Accesses to .rodata can't race, so this saves time, memory and trace space.
MapRodata()148 static void MapRodata() {
149   // First create temp file.
150   const char *tmpdir = GetEnv("TMPDIR");
151   if (tmpdir == 0)
152     tmpdir = GetEnv("TEST_TMPDIR");
153 #ifdef P_tmpdir
154   if (tmpdir == 0)
155     tmpdir = P_tmpdir;
156 #endif
157   if (tmpdir == 0)
158     return;
159   char name[256];
160   internal_snprintf(name, sizeof(name), "%s/tsan.rodata.%d",
161                     tmpdir, (int)internal_getpid());
162   uptr openrv = internal_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
163   if (internal_iserror(openrv))
164     return;
165   internal_unlink(name);  // Unlink it now, so that we can reuse the buffer.
166   fd_t fd = openrv;
167   // Fill the file with kShadowRodata.
168   const uptr kMarkerSize = 512 * 1024 / sizeof(u64);
169   InternalScopedBuffer<u64> marker(kMarkerSize);
170   // volatile to prevent insertion of memset
171   for (volatile u64 *p = marker.data(); p < marker.data() + kMarkerSize; p++)
172     *p = kShadowRodata;
173   internal_write(fd, marker.data(), marker.size());
174   // Map the file into memory.
175   uptr page = internal_mmap(0, GetPageSizeCached(), PROT_READ | PROT_WRITE,
176                             MAP_PRIVATE | MAP_ANONYMOUS, fd, 0);
177   if (internal_iserror(page)) {
178     internal_close(fd);
179     return;
180   }
181   // Map the file into shadow of .rodata sections.
182   MemoryMappingLayout proc_maps(/*cache_enabled*/true);
183   uptr start, end, offset, prot;
184   // Reusing the buffer 'name'.
185   while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name), &prot)) {
186     if (name[0] != 0 && name[0] != '['
187         && (prot & MemoryMappingLayout::kProtectionRead)
188         && (prot & MemoryMappingLayout::kProtectionExecute)
189         && !(prot & MemoryMappingLayout::kProtectionWrite)
190         && IsAppMem(start)) {
191       // Assume it's .rodata
192       char *shadow_start = (char*)MemToShadow(start);
193       char *shadow_end = (char*)MemToShadow(end);
194       for (char *p = shadow_start; p < shadow_end; p += marker.size()) {
195         internal_mmap(p, Min<uptr>(marker.size(), shadow_end - p),
196                       PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, 0);
197       }
198     }
199   }
200   internal_close(fd);
201 }
202 
InitializeShadowMemory()203 void InitializeShadowMemory() {
204   // Map memory shadow.
205   uptr shadow = (uptr)MmapFixedNoReserve(kShadowBeg,
206     kShadowEnd - kShadowBeg);
207   if (shadow != kShadowBeg) {
208     Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
209     Printf("FATAL: Make sure to compile with -fPIE and "
210                "to link with -pie (%p, %p).\n", shadow, kShadowBeg);
211     Die();
212   }
213   // This memory range is used for thread stacks and large user mmaps.
214   // Frequently a thread uses only a small part of stack and similarly
215   // a program uses a small part of large mmap. On some programs
216   // we see 20% memory usage reduction without huge pages for this range.
217   // FIXME: don't use constants here.
218 #if defined(__x86_64__)
219   const uptr kMadviseRangeBeg  = 0x7f0000000000ull;
220   const uptr kMadviseRangeSize = 0x010000000000ull;
221 #elif defined(__mips64)
222   const uptr kMadviseRangeBeg  = 0xff00000000ull;
223   const uptr kMadviseRangeSize = 0x0100000000ull;
224 #endif
225   NoHugePagesInRegion(MemToShadow(kMadviseRangeBeg),
226                       kMadviseRangeSize * kShadowMultiplier);
227   if (common_flags()->use_madv_dontdump)
228     DontDumpShadowMemory(kShadowBeg, kShadowEnd - kShadowBeg);
229   DPrintf("memory shadow: %zx-%zx (%zuGB)\n",
230       kShadowBeg, kShadowEnd,
231       (kShadowEnd - kShadowBeg) >> 30);
232 
233   // Map meta shadow.
234   uptr meta_size = kMetaShadowEnd - kMetaShadowBeg;
235   uptr meta = (uptr)MmapFixedNoReserve(kMetaShadowBeg, meta_size);
236   if (meta != kMetaShadowBeg) {
237     Printf("FATAL: ThreadSanitizer can not mmap the shadow memory\n");
238     Printf("FATAL: Make sure to compile with -fPIE and "
239                "to link with -pie (%p, %p).\n", meta, kMetaShadowBeg);
240     Die();
241   }
242   if (common_flags()->use_madv_dontdump)
243     DontDumpShadowMemory(meta, meta_size);
244   DPrintf("meta shadow: %zx-%zx (%zuGB)\n",
245       meta, meta + meta_size, meta_size >> 30);
246 
247   MapRodata();
248 }
249 
InitDataSeg()250 static void InitDataSeg() {
251   MemoryMappingLayout proc_maps(true);
252   uptr start, end, offset;
253   char name[128];
254 #if SANITIZER_FREEBSD
255   // On FreeBSD BSS is usually the last block allocated within the
256   // low range and heap is the last block allocated within the range
257   // 0x800000000-0x8ffffffff.
258   while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name),
259                         /*protection*/ 0)) {
260     DPrintf("%p-%p %p %s\n", start, end, offset, name);
261     if ((start & 0xffff00000000ULL) == 0 && (end & 0xffff00000000ULL) == 0 &&
262         name[0] == '\0') {
263       g_data_start = start;
264       g_data_end = end;
265     }
266   }
267 #else
268   bool prev_is_data = false;
269   while (proc_maps.Next(&start, &end, &offset, name, ARRAY_SIZE(name),
270                         /*protection*/ 0)) {
271     DPrintf("%p-%p %p %s\n", start, end, offset, name);
272     bool is_data = offset != 0 && name[0] != 0;
273     // BSS may get merged with [heap] in /proc/self/maps. This is not very
274     // reliable.
275     bool is_bss = offset == 0 &&
276       (name[0] == 0 || internal_strcmp(name, "[heap]") == 0) && prev_is_data;
277     if (g_data_start == 0 && is_data)
278       g_data_start = start;
279     if (is_bss)
280       g_data_end = end;
281     prev_is_data = is_data;
282   }
283 #endif
284   DPrintf("guessed data_start=%p data_end=%p\n",  g_data_start, g_data_end);
285   CHECK_LT(g_data_start, g_data_end);
286   CHECK_GE((uptr)&g_data_start, g_data_start);
287   CHECK_LT((uptr)&g_data_start, g_data_end);
288 }
289 
CheckAndProtect()290 static void CheckAndProtect() {
291   // Ensure that the binary is indeed compiled with -pie.
292   MemoryMappingLayout proc_maps(true);
293   uptr p, end;
294   while (proc_maps.Next(&p, &end, 0, 0, 0, 0)) {
295     if (IsAppMem(p))
296       continue;
297     if (p >= kHeapMemEnd &&
298         p < HeapEnd())
299       continue;
300     if (p >= kVdsoBeg)  // vdso
301       break;
302     Printf("FATAL: ThreadSanitizer: unexpected memory mapping %p-%p\n", p, end);
303     Die();
304   }
305 
306   ProtectRange(kLoAppMemEnd, kShadowBeg);
307   ProtectRange(kShadowEnd, kMetaShadowBeg);
308   ProtectRange(kMetaShadowEnd, kTraceMemBeg);
309   // Memory for traces is mapped lazily in MapThreadTrace.
310   // Protect the whole range for now, so that user does not map something here.
311   ProtectRange(kTraceMemBeg, kTraceMemEnd);
312   ProtectRange(kTraceMemEnd, kHeapMemBeg);
313   ProtectRange(HeapEnd(), kHiAppMemBeg);
314 }
315 #endif  // #ifndef SANITIZER_GO
316 
InitializePlatform()317 void InitializePlatform() {
318   DisableCoreDumperIfNecessary();
319 
320   // Go maps shadow memory lazily and works fine with limited address space.
321   // Unlimited stack is not a problem as well, because the executable
322   // is not compiled with -pie.
323   if (kCppMode) {
324     bool reexec = false;
325     // TSan doesn't play well with unlimited stack size (as stack
326     // overlaps with shadow memory). If we detect unlimited stack size,
327     // we re-exec the program with limited stack size as a best effort.
328     if (StackSizeIsUnlimited()) {
329       const uptr kMaxStackSize = 32 * 1024 * 1024;
330       VReport(1, "Program is run with unlimited stack size, which wouldn't "
331                  "work with ThreadSanitizer.\n"
332                  "Re-execing with stack size limited to %zd bytes.\n",
333               kMaxStackSize);
334       SetStackSizeLimitInBytes(kMaxStackSize);
335       reexec = true;
336     }
337 
338     if (!AddressSpaceIsUnlimited()) {
339       Report("WARNING: Program is run with limited virtual address space,"
340              " which wouldn't work with ThreadSanitizer.\n");
341       Report("Re-execing with unlimited virtual address space.\n");
342       SetAddressSpaceUnlimited();
343       reexec = true;
344     }
345     if (reexec)
346       ReExec();
347   }
348 
349 #ifndef SANITIZER_GO
350   CheckAndProtect();
351   InitTlsSize();
352   InitDataSeg();
353 #endif
354 }
355 
IsGlobalVar(uptr addr)356 bool IsGlobalVar(uptr addr) {
357   return g_data_start && addr >= g_data_start && addr < g_data_end;
358 }
359 
360 #ifndef SANITIZER_GO
361 // Extract file descriptors passed to glibc internal __res_iclose function.
362 // This is required to properly "close" the fds, because we do not see internal
363 // closes within glibc. The code is a pure hack.
ExtractResolvFDs(void * state,int * fds,int nfd)364 int ExtractResolvFDs(void *state, int *fds, int nfd) {
365 #if SANITIZER_LINUX
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 #else
374   return 0;
375 #endif
376 }
377 
378 // Extract file descriptors passed via UNIX domain sockets.
379 // This is requried to properly handle "open" of these fds.
380 // see 'man recvmsg' and 'man 3 cmsg'.
ExtractRecvmsgFDs(void * msgp,int * fds,int nfd)381 int ExtractRecvmsgFDs(void *msgp, int *fds, int nfd) {
382   int res = 0;
383   msghdr *msg = (msghdr*)msgp;
384   struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
385   for (; cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
386     if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS)
387       continue;
388     int n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(fds[0]);
389     for (int i = 0; i < n; i++) {
390       fds[res++] = ((int*)CMSG_DATA(cmsg))[i];
391       if (res == nfd)
392         return res;
393     }
394   }
395   return res;
396 }
397 
398 // Note: this function runs with async signals enabled,
399 // so it must not touch any tsan state.
call_pthread_cancel_with_cleanup(int (* fn)(void * c,void * m,void * abstime),void * c,void * m,void * abstime,void (* cleanup)(void * arg),void * arg)400 int call_pthread_cancel_with_cleanup(int(*fn)(void *c, void *m,
401     void *abstime), void *c, void *m, void *abstime,
402     void(*cleanup)(void *arg), void *arg) {
403   // pthread_cleanup_push/pop are hardcore macros mess.
404   // We can't intercept nor call them w/o including pthread.h.
405   int res;
406   pthread_cleanup_push(cleanup, arg);
407   res = fn(c, m, abstime);
408   pthread_cleanup_pop(0);
409   return res;
410 }
411 #endif
412 
413 }  // namespace __tsan
414 
415 #endif  // SANITIZER_LINUX || SANITIZER_FREEBSD
416