libsanitizer/sanitizer_common/sanitizer_linux.cc

   1 //===-- sanitizer_linux.cc ------------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer
   9 // run-time libraries and implements linux-specific functions from
  10 // sanitizer_libc.h.
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "sanitizer_platform.h"
  14 #if SANITIZER_LINUX
  15
  16 #include "sanitizer_common.h"
  17 #include "sanitizer_internal_defs.h"
  18 #include "sanitizer_libc.h"
  19 #include "sanitizer_linux.h"
  20 #include "sanitizer_mutex.h"
  21 #include "sanitizer_placement_new.h"
  22 #include "sanitizer_procmaps.h"
  23 #include "sanitizer_stacktrace.h"
  24 #include "sanitizer_symbolizer.h"
  25
  26 #include <asm/param.h>
  27 #include <dlfcn.h>
  28 #include <errno.h>
  29 #include <fcntl.h>
  30 #if !SANITIZER_ANDROID
  31 #include <link.h>
  32 #endif
  33 #include <pthread.h>
  34 #include <sched.h>
  35 #include <sys/mman.h>
  36 #include <sys/ptrace.h>
  37 #include <sys/resource.h>
  38 #include <sys/stat.h>
  39 #include <sys/syscall.h>
  40 #include <sys/time.h>
  41 #include <sys/types.h>
  42 #include <unistd.h>
  43 #include <unwind.h>
  44
  45 #if !SANITIZER_ANDROID
  46 #include <sys/signal.h>
  47 #endif
  48
  49 // <linux/time.h>
  50 struct kernel_timeval {
  51   long tv_sec;
  52   long tv_usec;
  53 };
  54
  55 // <linux/futex.h> is broken on some linux distributions.
  56 const int FUTEX_WAIT = 0;
  57 const int FUTEX_WAKE = 1;
  58
  59 // Are we using 32-bit or 64-bit syscalls?
  60 // x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
  61 // but it still needs to use 64-bit syscalls.
  62 #if defined(__x86_64__) || SANITIZER_WORDSIZE == 64
  63 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
  64 #else
  65 # define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
  66 #endif
  67
  68 namespace __sanitizer {
  69
  70 #ifdef __x86_64__
  71 #include "sanitizer_syscall_linux_x86_64.inc"
  72 #else
  73 #include "sanitizer_syscall_generic.inc"
  74 #endif
  75
  76 // --------------- sanitizer_libc.h
  77 uptr internal_mmap(void *addr, uptr length, int prot, int flags,
  78                     int fd, u64 offset) {
  79 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
  80   return internal_syscall(__NR_mmap, (uptr)addr, length, prot, flags, fd,
  81                           offset);
  82 #else
  83   return internal_syscall(__NR_mmap2, addr, length, prot, flags, fd, offset);
  84 #endif
  85 }
  86
  87 uptr internal_munmap(void *addr, uptr length) {
  88   return internal_syscall(__NR_munmap, (uptr)addr, length);
  89 }
  90
  91 uptr internal_close(fd_t fd) {
  92   return internal_syscall(__NR_close, fd);
  93 }
  94
  95 uptr internal_open(const char *filename, int flags) {
  96   return internal_syscall(__NR_open, (uptr)filename, flags);
  97 }
  98
  99 uptr internal_open(const char *filename, int flags, u32 mode) {
 100   return internal_syscall(__NR_open, (uptr)filename, flags, mode);
 101 }
 102
 103 uptr OpenFile(const char *filename, bool write) {
 104   return internal_open(filename,
 105       write ? O_WRONLY | O_CREAT /*| O_CLOEXEC*/ : O_RDONLY, 0660);
 106 }
 107
 108 uptr internal_read(fd_t fd, void *buf, uptr count) {
 109   sptr res;
 110   HANDLE_EINTR(res, (sptr)internal_syscall(__NR_read, fd, (uptr)buf, count));
 111   return res;
 112 }
 113
 114 uptr internal_write(fd_t fd, const void *buf, uptr count) {
 115   sptr res;
 116   HANDLE_EINTR(res, (sptr)internal_syscall(__NR_write, fd, (uptr)buf, count));
 117   return res;
 118 }
 119
 120 #if !SANITIZER_LINUX_USES_64BIT_SYSCALLS
 121 static void stat64_to_stat(struct stat64 *in, struct stat *out) {
 122   internal_memset(out, 0, sizeof(*out));
 123   out->st_dev = in->st_dev;
 124   out->st_ino = in->st_ino;
 125   out->st_mode = in->st_mode;
 126   out->st_nlink = in->st_nlink;
 127   out->st_uid = in->st_uid;
 128   out->st_gid = in->st_gid;
 129   out->st_rdev = in->st_rdev;
 130   out->st_size = in->st_size;
 131   out->st_blksize = in->st_blksize;
 132   out->st_blocks = in->st_blocks;
 133   out->st_atime = in->st_atime;
 134   out->st_mtime = in->st_mtime;
 135   out->st_ctime = in->st_ctime;
 136   out->st_ino = in->st_ino;
 137 }
 138 #endif
 139
 140 uptr internal_stat(const char *path, void *buf) {
 141 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 142   return internal_syscall(__NR_stat, (uptr)path, (uptr)buf);
 143 #else
 144   struct stat64 buf64;
 145   int res = internal_syscall(__NR_stat64, path, &buf64);
 146   stat64_to_stat(&buf64, (struct stat *)buf);
 147   return res;
 148 #endif
 149 }
 150
 151 uptr internal_lstat(const char *path, void *buf) {
 152 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 153   return internal_syscall(__NR_lstat, (uptr)path, (uptr)buf);
 154 #else
 155   struct stat64 buf64;
 156   int res = internal_syscall(__NR_lstat64, path, &buf64);
 157   stat64_to_stat(&buf64, (struct stat *)buf);
 158   return res;
 159 #endif
 160 }
 161
 162 uptr internal_fstat(fd_t fd, void *buf) {
 163 #if SANITIZER_LINUX_USES_64BIT_SYSCALLS
 164   return internal_syscall(__NR_fstat, fd, (uptr)buf);
 165 #else
 166   struct stat64 buf64;
 167   int res = internal_syscall(__NR_fstat64, fd, &buf64);
 168   stat64_to_stat(&buf64, (struct stat *)buf);
 169   return res;
 170 #endif
 171 }
 172
 173 uptr internal_filesize(fd_t fd) {
 174   struct stat st;
 175   if (internal_fstat(fd, &st))
 176     return -1;
 177   return (uptr)st.st_size;
 178 }
 179
 180 uptr internal_dup2(int oldfd, int newfd) {
 181   return internal_syscall(__NR_dup2, oldfd, newfd);
 182 }
 183
 184 uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
 185   return internal_syscall(__NR_readlink, (uptr)path, (uptr)buf, bufsize);
 186 }
 187
 188 uptr internal_unlink(const char *path) {
 189   return internal_syscall(__NR_unlink, (uptr)path);
 190 }
 191
 192 uptr internal_sched_yield() {
 193   return internal_syscall(__NR_sched_yield);
 194 }
 195
 196 void internal__exit(int exitcode) {
 197   internal_syscall(__NR_exit_group, exitcode);
 198   Die();  // Unreachable.
 199 }
 200
 201 uptr internal_execve(const char *filename, char *const argv[],
 202                      char *const envp[]) {
 203   return internal_syscall(__NR_execve, (uptr)filename, (uptr)argv, (uptr)envp);
 204 }
 205
 206 // ----------------- sanitizer_common.h
 207 bool FileExists(const char *filename) {
 208   struct stat st;
 209   if (internal_stat(filename, &st))
 210     return false;
 211   // Sanity check: filename is a regular file.
 212   return S_ISREG(st.st_mode);
 213 }
 214
 215 uptr GetTid() {
 216   return internal_syscall(__NR_gettid);
 217 }
 218
 219 u64 NanoTime() {
 220   kernel_timeval tv;
 221   internal_memset(&tv, 0, sizeof(tv));
 222   internal_syscall(__NR_gettimeofday, (uptr)&tv, 0);
 223   return (u64)tv.tv_sec * 1000*1000*1000 + tv.tv_usec * 1000;
 224 }
 225
 226 // Like getenv, but reads env directly from /proc and does not use libc.
 227 // This function should be called first inside __asan_init.
 228 const char *GetEnv(const char *name) {
 229   static char *environ;
 230   static uptr len;
 231   static bool inited;
 232   if (!inited) {
 233     inited = true;
 234     uptr environ_size;
 235     len = ReadFileToBuffer("/proc/self/environ",
 236                            &environ, &environ_size, 1 << 26);
 237   }
 238   if (!environ || len == 0) return 0;
 239   uptr namelen = internal_strlen(name);
 240   const char *p = environ;
 241   while (*p != '\0') {  // will happen at the \0\0 that terminates the buffer
 242     // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
 243     const char* endp =
 244         (char*)internal_memchr(p, '\0', len - (p - environ));
 245     if (endp == 0)  // this entry isn't NUL terminated
 246       return 0;
 247     else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
 248       return p + namelen + 1;  // point after =
 249     p = endp + 1;
 250   }
 251   return 0;  // Not found.
 252 }
 253
 254 extern "C" {
 255   SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
 256 }
 257
 258 #if !SANITIZER_GO
 259 static void ReadNullSepFileToArray(const char *path, char ***arr,
 260                                    int arr_size) {
 261   char *buff;
 262   uptr buff_size = 0;
 263   *arr = (char **)MmapOrDie(arr_size * sizeof(char *), "NullSepFileArray");
 264   ReadFileToBuffer(path, &buff, &buff_size, 1024 * 1024);
 265   (*arr)[0] = buff;
 266   int count, i;
 267   for (count = 1, i = 1; ; i++) {
 268     if (buff[i] == 0) {
 269       if (buff[i+1] == 0) break;
 270       (*arr)[count] = &buff[i+1];
 271       CHECK_LE(count, arr_size - 1);  // FIXME: make this more flexible.
 272       count++;
 273     }
 274   }
 275   (*arr)[count] = 0;
 276 }
 277 #endif
 278
 279 static void GetArgsAndEnv(char*** argv, char*** envp) {
 280 #if !SANITIZER_GO
 281   if (&__libc_stack_end) {
 282 #endif
 283     uptr* stack_end = (uptr*)__libc_stack_end;
 284     int argc = *stack_end;
 285     *argv = (char**)(stack_end + 1);
 286     *envp = (char**)(stack_end + argc + 2);
 287 #if !SANITIZER_GO
 288   } else {
 289     static const int kMaxArgv = 2000, kMaxEnvp = 2000;
 290     ReadNullSepFileToArray("/proc/self/cmdline", argv, kMaxArgv);
 291     ReadNullSepFileToArray("/proc/self/environ", envp, kMaxEnvp);
 292   }
 293 #endif
 294 }
 295
 296 void ReExec() {
 297   char **argv, **envp;
 298   GetArgsAndEnv(&argv, &envp);
 299   uptr rv = internal_execve("/proc/self/exe", argv, envp);
 300   int rverrno;
 301   CHECK_EQ(internal_iserror(rv, &rverrno), true);
 302   Printf("execve failed, errno %d\n", rverrno);
 303   Die();
 304 }
 305
 306 void PrepareForSandboxing() {
 307   // Some kinds of sandboxes may forbid filesystem access, so we won't be able
 308   // to read the file mappings from /proc/self/maps. Luckily, neither the
 309   // process will be able to load additional libraries, so it's fine to use the
 310   // cached mappings.
 311   MemoryMappingLayout::CacheMemoryMappings();
 312   // Same for /proc/self/exe in the symbolizer.
 313 #if !SANITIZER_GO
 314   if (Symbolizer *sym = Symbolizer::GetOrNull())
 315     sym->PrepareForSandboxing();
 316 #endif
 317 }
 318
 319 // ----------------- sanitizer_procmaps.h
 320 // Linker initialized.
 321 ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
 322 StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
 323
 324 MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
 325   proc_self_maps_.len =
 326       ReadFileToBuffer("/proc/self/maps", &proc_self_maps_.data,
 327                        &proc_self_maps_.mmaped_size, 1 << 26);
 328   if (cache_enabled) {
 329     if (proc_self_maps_.mmaped_size == 0) {
 330       LoadFromCache();
 331       CHECK_GT(proc_self_maps_.len, 0);
 332     }
 333   } else {
 334     CHECK_GT(proc_self_maps_.mmaped_size, 0);
 335   }
 336   Reset();
 337   // FIXME: in the future we may want to cache the mappings on demand only.
 338   if (cache_enabled)
 339     CacheMemoryMappings();
 340 }
 341
 342 MemoryMappingLayout::~MemoryMappingLayout() {
 343   // Only unmap the buffer if it is different from the cached one. Otherwise
 344   // it will be unmapped when the cache is refreshed.
 345   if (proc_self_maps_.data != cached_proc_self_maps_.data) {
 346     UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
 347   }
 348 }
 349
 350 void MemoryMappingLayout::Reset() {
 351   current_ = proc_self_maps_.data;
 352 }
 353
 354 // static
 355 void MemoryMappingLayout::CacheMemoryMappings() {
 356   SpinMutexLock l(&cache_lock_);
 357   // Don't invalidate the cache if the mappings are unavailable.
 358   ProcSelfMapsBuff old_proc_self_maps;
 359   old_proc_self_maps = cached_proc_self_maps_;
 360   cached_proc_self_maps_.len =
 361       ReadFileToBuffer("/proc/self/maps", &cached_proc_self_maps_.data,
 362                        &cached_proc_self_maps_.mmaped_size, 1 << 26);
 363   if (cached_proc_self_maps_.mmaped_size == 0) {
 364     cached_proc_self_maps_ = old_proc_self_maps;
 365   } else {
 366     if (old_proc_self_maps.mmaped_size) {
 367       UnmapOrDie(old_proc_self_maps.data,
 368                  old_proc_self_maps.mmaped_size);
 369     }
 370   }
 371 }
 372
 373 void MemoryMappingLayout::LoadFromCache() {
 374   SpinMutexLock l(&cache_lock_);
 375   if (cached_proc_self_maps_.data) {
 376     proc_self_maps_ = cached_proc_self_maps_;
 377   }
 378 }
 379
 380 // Parse a hex value in str and update str.
 381 static uptr ParseHex(char **str) {
 382   uptr x = 0;
 383   char *s;
 384   for (s = *str; ; s++) {
 385     char c = *s;
 386     uptr v = 0;
 387     if (c >= '0' && c <= '9')
 388       v = c - '0';
 389     else if (c >= 'a' && c <= 'f')
 390       v = c - 'a' + 10;
 391     else if (c >= 'A' && c <= 'F')
 392       v = c - 'A' + 10;
 393     else
 394       break;
 395     x = x * 16 + v;
 396   }
 397   *str = s;
 398   return x;
 399 }
 400
 401 static bool IsOneOf(char c, char c1, char c2) {
 402   return c == c1 || c == c2;
 403 }
 404
 405 static bool IsDecimal(char c) {
 406   return c >= '0' && c <= '9';
 407 }
 408
 409 static bool IsHex(char c) {
 410   return (c >= '0' && c <= '9')
 411       || (c >= 'a' && c <= 'f');
 412 }
 413
 414 static uptr ReadHex(const char *p) {
 415   uptr v = 0;
 416   for (; IsHex(p[0]); p++) {
 417     if (p[0] >= '0' && p[0] <= '9')
 418       v = v * 16 + p[0] - '0';
 419     else
 420       v = v * 16 + p[0] - 'a' + 10;
 421   }
 422   return v;
 423 }
 424
 425 static uptr ReadDecimal(const char *p) {
 426   uptr v = 0;
 427   for (; IsDecimal(p[0]); p++)
 428     v = v * 10 + p[0] - '0';
 429   return v;
 430 }
 431
 432
 433 bool MemoryMappingLayout::Next(uptr *start, uptr *end, uptr *offset,
 434                                char filename[], uptr filename_size,
 435                                uptr *protection) {
 436   char *last = proc_self_maps_.data + proc_self_maps_.len;
 437   if (current_ >= last) return false;
 438   uptr dummy;
 439   if (!start) start = &dummy;
 440   if (!end) end = &dummy;
 441   if (!offset) offset = &dummy;
 442   char *next_line = (char*)internal_memchr(current_, '\n', last - current_);
 443   if (next_line == 0)
 444     next_line = last;
 445   // Example: 08048000-08056000 r-xp 00000000 03:0c 64593   /foo/bar
 446   *start = ParseHex(&current_);
 447   CHECK_EQ(*current_++, '-');
 448   *end = ParseHex(&current_);
 449   CHECK_EQ(*current_++, ' ');
 450   uptr local_protection = 0;
 451   CHECK(IsOneOf(*current_, '-', 'r'));
 452   if (*current_++ == 'r')
 453     local_protection |= kProtectionRead;
 454   CHECK(IsOneOf(*current_, '-', 'w'));
 455   if (*current_++ == 'w')
 456     local_protection |= kProtectionWrite;
 457   CHECK(IsOneOf(*current_, '-', 'x'));
 458   if (*current_++ == 'x')
 459     local_protection |= kProtectionExecute;
 460   CHECK(IsOneOf(*current_, 's', 'p'));
 461   if (*current_++ == 's')
 462     local_protection |= kProtectionShared;
 463   if (protection) {
 464     *protection = local_protection;
 465   }
 466   CHECK_EQ(*current_++, ' ');
 467   *offset = ParseHex(&current_);
 468   CHECK_EQ(*current_++, ' ');
 469   ParseHex(&current_);
 470   CHECK_EQ(*current_++, ':');
 471   ParseHex(&current_);
 472   CHECK_EQ(*current_++, ' ');
 473   while (IsDecimal(*current_))
 474     current_++;
 475   // Qemu may lack the trailing space.
 476   // http://code.google.com/p/address-sanitizer/issues/detail?id=160
 477   // CHECK_EQ(*current_++, ' ');
 478   // Skip spaces.
 479   while (current_ < next_line && *current_ == ' ')
 480     current_++;
 481   // Fill in the filename.
 482   uptr i = 0;
 483   while (current_ < next_line) {
 484     if (filename && i < filename_size - 1)
 485       filename[i++] = *current_;
 486     current_++;
 487   }
 488   if (filename && i < filename_size)
 489     filename[i] = 0;
 490   current_ = next_line + 1;
 491   return true;
 492 }
 493
 494 // Gets the object name and the offset by walking MemoryMappingLayout.
 495 bool MemoryMappingLayout::GetObjectNameAndOffset(uptr addr, uptr *offset,
 496                                                  char filename[],
 497                                                  uptr filename_size,
 498                                                  uptr *protection) {
 499   return IterateForObjectNameAndOffset(addr, offset, filename, filename_size,
 500                                        protection);
 501 }
 502
 503 void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) {
 504   char *smaps = 0;
 505   uptr smaps_cap = 0;
 506   uptr smaps_len = ReadFileToBuffer("/proc/self/smaps",
 507       &smaps, &smaps_cap, 64<<20);
 508   uptr start = 0;
 509   bool file = false;
 510   const char *pos = smaps;
 511   while (pos < smaps + smaps_len) {
 512     if (IsHex(pos[0])) {
 513       start = ReadHex(pos);
 514       for (; *pos != '/' && *pos > '\n'; pos++) {}
 515       file = *pos == '/';
 516     } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
 517       for (; *pos < '0' || *pos > '9'; pos++) {}
 518       uptr rss = ReadDecimal(pos) * 1024;
 519       cb(start, rss, file, stats, stats_size);
 520     }
 521     while (*pos++ != '\n') {}
 522   }
 523   UnmapOrDie(smaps, smaps_cap);
 524 }
 525
 526 enum MutexState {
 527   MtxUnlocked = 0,
 528   MtxLocked = 1,
 529   MtxSleeping = 2
 530 };
 531
 532 BlockingMutex::BlockingMutex(LinkerInitialized) {
 533   CHECK_EQ(owner_, 0);
 534 }
 535
 536 BlockingMutex::BlockingMutex() {
 537   internal_memset(this, 0, sizeof(*this));
 538 }
 539
 540 void BlockingMutex::Lock() {
 541   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 542   if (atomic_exchange(m, MtxLocked, memory_order_acquire) == MtxUnlocked)
 543     return;
 544   while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked)
 545     internal_syscall(__NR_futex, (uptr)m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
 546 }
 547
 548 void BlockingMutex::Unlock() {
 549   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 550   u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
 551   CHECK_NE(v, MtxUnlocked);
 552   if (v == MtxSleeping)
 553     internal_syscall(__NR_futex, (uptr)m, FUTEX_WAKE, 1, 0, 0, 0);
 554 }
 555
 556 void BlockingMutex::CheckLocked() {
 557   atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
 558   CHECK_NE(MtxUnlocked, atomic_load(m, memory_order_relaxed));
 559 }
 560
 561 // ----------------- sanitizer_linux.h
 562 // The actual size of this structure is specified by d_reclen.
 563 // Note that getdents64 uses a different structure format. We only provide the
 564 // 32-bit syscall here.
 565 struct linux_dirent {
 566   unsigned long      d_ino;
 567   unsigned long      d_off;
 568   unsigned short     d_reclen;
 569   char               d_name[256];
 570 };
 571
 572 // Syscall wrappers.
 573 uptr internal_ptrace(int request, int pid, void *addr, void *data) {
 574   return internal_syscall(__NR_ptrace, request, pid, (uptr)addr, (uptr)data);
 575 }
 576
 577 uptr internal_waitpid(int pid, int *status, int options) {
 578   return internal_syscall(__NR_wait4, pid, (uptr)status, options,
 579                           0 /* rusage */);
 580 }
 581
 582 uptr internal_getpid() {
 583   return internal_syscall(__NR_getpid);
 584 }
 585
 586 uptr internal_getppid() {
 587   return internal_syscall(__NR_getppid);
 588 }
 589
 590 uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count) {
 591   return internal_syscall(__NR_getdents, fd, (uptr)dirp, count);
 592 }
 593
 594 uptr internal_lseek(fd_t fd, OFF_T offset, int whence) {
 595   return internal_syscall(__NR_lseek, fd, offset, whence);
 596 }
 597
 598 uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
 599   return internal_syscall(__NR_prctl, option, arg2, arg3, arg4, arg5);
 600 }
 601
 602 uptr internal_sigaltstack(const struct sigaltstack *ss,
 603                          struct sigaltstack *oss) {
 604   return internal_syscall(__NR_sigaltstack, (uptr)ss, (uptr)oss);
 605 }
 606
 607 uptr internal_sigaction(int signum, const __sanitizer_kernel_sigaction_t *act,
 608     __sanitizer_kernel_sigaction_t *oldact) {
 609   return internal_syscall(__NR_rt_sigaction, signum, act, oldact,
 610       sizeof(__sanitizer_kernel_sigset_t));
 611 }
 612
 613 uptr internal_sigprocmask(int how, __sanitizer_kernel_sigset_t *set,
 614     __sanitizer_kernel_sigset_t *oldset) {
 615   return internal_syscall(__NR_rt_sigprocmask, (uptr)how, &set->sig[0],
 616       &oldset->sig[0], sizeof(__sanitizer_kernel_sigset_t));
 617 }
 618
 619 void internal_sigfillset(__sanitizer_kernel_sigset_t *set) {
 620   internal_memset(set, 0xff, sizeof(*set));
 621 }
 622
 623 void internal_sigdelset(__sanitizer_kernel_sigset_t *set, int signum) {
 624   signum -= 1;
 625   CHECK_GE(signum, 0);
 626   CHECK_LT(signum, sizeof(*set) * 8);
 627   const uptr idx = signum / (sizeof(set->sig[0]) * 8);
 628   const uptr bit = signum % (sizeof(set->sig[0]) * 8);
 629   set->sig[idx] &= ~(1 << bit);
 630 }
 631
 632 // ThreadLister implementation.
 633 ThreadLister::ThreadLister(int pid)
 634   : pid_(pid),
 635     descriptor_(-1),
 636     buffer_(4096),
 637     error_(true),
 638     entry_((struct linux_dirent *)buffer_.data()),
 639     bytes_read_(0) {
 640   char task_directory_path[80];
 641   internal_snprintf(task_directory_path, sizeof(task_directory_path),
 642                     "/proc/%d/task/", pid);
 643   uptr openrv = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
 644   if (internal_iserror(openrv)) {
 645     error_ = true;
 646     Report("Can't open /proc/%d/task for reading.\n", pid);
 647   } else {
 648     error_ = false;
 649     descriptor_ = openrv;
 650   }
 651 }
 652
 653 int ThreadLister::GetNextTID() {
 654   int tid = -1;
 655   do {
 656     if (error_)
 657       return -1;
 658     if ((char *)entry_ >= &buffer_[bytes_read_] && !GetDirectoryEntries())
 659       return -1;
 660     if (entry_->d_ino != 0 && entry_->d_name[0] >= '0' &&
 661         entry_->d_name[0] <= '9') {
 662       // Found a valid tid.
 663       tid = (int)internal_atoll(entry_->d_name);
 664     }
 665     entry_ = (struct linux_dirent *)(((char *)entry_) + entry_->d_reclen);
 666   } while (tid < 0);
 667   return tid;
 668 }
 669
 670 void ThreadLister::Reset() {
 671   if (error_ || descriptor_ < 0)
 672     return;
 673   internal_lseek(descriptor_, 0, SEEK_SET);
 674 }
 675
 676 ThreadLister::~ThreadLister() {
 677   if (descriptor_ >= 0)
 678     internal_close(descriptor_);
 679 }
 680
 681 bool ThreadLister::error() { return error_; }
 682
 683 bool ThreadLister::GetDirectoryEntries() {
 684   CHECK_GE(descriptor_, 0);
 685   CHECK_NE(error_, true);
 686   bytes_read_ = internal_getdents(descriptor_,
 687                                   (struct linux_dirent *)buffer_.data(),
 688                                   buffer_.size());
 689   if (internal_iserror(bytes_read_)) {
 690     Report("Can't read directory entries from /proc/%d/task.\n", pid_);
 691     error_ = true;
 692     return false;
 693   } else if (bytes_read_ == 0) {
 694     return false;
 695   }
 696   entry_ = (struct linux_dirent *)buffer_.data();
 697   return true;
 698 }
 699
 700 uptr GetPageSize() {
 701 #if defined(__x86_64__) || defined(__i386__)
 702   return EXEC_PAGESIZE;
 703 #else
 704   return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
 705 #endif
 706 }
 707
 708 static char proc_self_exe_cache_str[kMaxPathLength];
 709 static uptr proc_self_exe_cache_len = 0;
 710
 711 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
 712   uptr module_name_len = internal_readlink(
 713       "/proc/self/exe", buf, buf_len);
 714   int readlink_error;
 715   if (internal_iserror(module_name_len, &readlink_error)) {
 716     if (proc_self_exe_cache_len) {
 717       // If available, use the cached module name.
 718       CHECK_LE(proc_self_exe_cache_len, buf_len);
 719       internal_strncpy(buf, proc_self_exe_cache_str, buf_len);
 720       module_name_len = internal_strlen(proc_self_exe_cache_str);
 721     } else {
 722       // We can't read /proc/self/exe for some reason, assume the name of the
 723       // binary is unknown.
 724       Report("WARNING: readlink(\"/proc/self/exe\") failed with errno %d, "
 725              "some stack frames may not be symbolized\n", readlink_error);
 726       module_name_len = internal_snprintf(buf, buf_len, "/proc/self/exe");
 727     }
 728     CHECK_LT(module_name_len, buf_len);
 729     buf[module_name_len] = '\0';
 730   }
 731   return module_name_len;
 732 }
 733
 734 void CacheBinaryName() {
 735   if (!proc_self_exe_cache_len) {
 736     proc_self_exe_cache_len =
 737         ReadBinaryName(proc_self_exe_cache_str, kMaxPathLength);
 738   }
 739 }
 740
 741 // Match full names of the form /path/to/base_name{-,.}*
 742 bool LibraryNameIs(const char *full_name, const char *base_name) {
 743   const char *name = full_name;
 744   // Strip path.
 745   while (*name != '\0') name++;
 746   while (name > full_name && *name != '/') name--;
 747   if (*name == '/') name++;
 748   uptr base_name_length = internal_strlen(base_name);
 749   if (internal_strncmp(name, base_name, base_name_length)) return false;
 750   return (name[base_name_length] == '-' || name[base_name_length] == '.');
 751 }
 752
 753 #if !SANITIZER_ANDROID
 754 // Call cb for each region mapped by map.
 755 void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
 756   typedef ElfW(Phdr) Elf_Phdr;
 757   typedef ElfW(Ehdr) Elf_Ehdr;
 758   char *base = (char *)map->l_addr;
 759   Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
 760   char *phdrs = base + ehdr->e_phoff;
 761   char *phdrs_end = phdrs + ehdr->e_phnum * ehdr->e_phentsize;
 762
 763   // Find the segment with the minimum base so we can "relocate" the p_vaddr
 764   // fields.  Typically ET_DYN objects (DSOs) have base of zero and ET_EXEC
 765   // objects have a non-zero base.
 766   uptr preferred_base = (uptr)-1;
 767   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
 768     Elf_Phdr *phdr = (Elf_Phdr *)iter;
 769     if (phdr->p_type == PT_LOAD && preferred_base > (uptr)phdr->p_vaddr)
 770       preferred_base = (uptr)phdr->p_vaddr;
 771   }
 772
 773   // Compute the delta from the real base to get a relocation delta.
 774   sptr delta = (uptr)base - preferred_base;
 775   // Now we can figure out what the loader really mapped.
 776   for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
 777     Elf_Phdr *phdr = (Elf_Phdr *)iter;
 778     if (phdr->p_type == PT_LOAD) {
 779       uptr seg_start = phdr->p_vaddr + delta;
 780       uptr seg_end = seg_start + phdr->p_memsz;
 781       // None of these values are aligned.  We consider the ragged edges of the
 782       // load command as defined, since they are mapped from the file.
 783       seg_start = RoundDownTo(seg_start, GetPageSizeCached());
 784       seg_end = RoundUpTo(seg_end, GetPageSizeCached());
 785       cb((void *)seg_start, seg_end - seg_start);
 786     }
 787   }
 788 }
 789 #endif
 790
 791 #if defined(__x86_64__)
 792 // We cannot use glibc's clone wrapper, because it messes with the child
 793 // task's TLS. It writes the PID and TID of the child task to its thread
 794 // descriptor, but in our case the child task shares the thread descriptor with
 795 // the parent (because we don't know how to allocate a new thread
 796 // descriptor to keep glibc happy). So the stock version of clone(), when
 797 // used with CLONE_VM, would end up corrupting the parent's thread descriptor.
 798 uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
 799                     int *parent_tidptr, void *newtls, int *child_tidptr) {
 800   long long res;
 801   if (!fn || !child_stack)
 802     return -EINVAL;
 803   CHECK_EQ(0, (uptr)child_stack % 16);
 804   child_stack = (char *)child_stack - 2 * sizeof(unsigned long long);
 805   ((unsigned long long *)child_stack)[0] = (uptr)fn;
 806   ((unsigned long long *)child_stack)[1] = (uptr)arg;
 807   register void *r8 __asm__("r8") = newtls;
 808   register int *r10 __asm__("r10") = child_tidptr;
 809   __asm__ __volatile__(
 810                        /* %rax = syscall(%rax = __NR_clone,
 811                         *                %rdi = flags,
 812                         *                %rsi = child_stack,
 813                         *                %rdx = parent_tidptr,
 814                         *                %r8  = new_tls,
 815                         *                %r10 = child_tidptr)
 816                         */
 817                        "syscall\n"
 818
 819                        /* if (%rax != 0)
 820                         *   return;
 821                         */
 822                        "testq  %%rax,%%rax\n"
 823                        "jnz    1f\n"
 824
 825                        /* In the child. Terminate unwind chain. */
 826                        // XXX: We should also terminate the CFI unwind chain
 827                        // here. Unfortunately clang 3.2 doesn't support the
 828                        // necessary CFI directives, so we skip that part.
 829                        "xorq   %%rbp,%%rbp\n"
 830
 831                        /* Call "fn(arg)". */
 832                        "popq   %%rax\n"
 833                        "popq   %%rdi\n"
 834                        "call   *%%rax\n"
 835
 836                        /* Call _exit(%rax). */
 837                        "movq   %%rax,%%rdi\n"
 838                        "movq   %2,%%rax\n"
 839                        "syscall\n"
 840
 841                        /* Return to parent. */
 842                      "1:\n"
 843                        : "=a" (res)
 844                        : "a"(__NR_clone), "i"(__NR_exit),
 845                          "S"(child_stack),
 846                          "D"(flags),
 847                          "d"(parent_tidptr),
 848                          "r"(r8),
 849                          "r"(r10)
 850                        : "rsp", "memory", "r11", "rcx");
 851   return res;
 852 }
 853 #endif  // defined(__x86_64__)
 854 }  // namespace __sanitizer
 855
 856 #endif  // SANITIZER_LINUX