sanitizer_linux.cc revision 7847d77b246635211c3bf465421d49d7af5226c1 
1//===-- sanitizer_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 shared between AddressSanitizer and ThreadSanitizer
11// run-time libraries and implements linux-specific functions from
12// sanitizer_libc.h.
13//===----------------------------------------------------------------------===//
14
15#include "sanitizer_platform.h"
16#if SANITIZER_LINUX
17
18#include "sanitizer_common.h"
19#include "sanitizer_internal_defs.h"
20#include "sanitizer_libc.h"
21#include "sanitizer_linux.h"
22#include "sanitizer_mutex.h"
23#include "sanitizer_placement_new.h"
24#include "sanitizer_procmaps.h"
25#include "sanitizer_stacktrace.h"
26#include "sanitizer_symbolizer.h"
27
28#include <asm/param.h>
29#include <dlfcn.h>
30#include <errno.h>
31#include <fcntl.h>
32#if !SANITIZER_ANDROID
33#include <link.h>
34#endif
35#include <pthread.h>
36#include <sched.h>
37#include <sys/mman.h>
38#include <sys/ptrace.h>
39#include <sys/resource.h>
40#include <sys/stat.h>
41#include <sys/syscall.h>
42#include <sys/time.h>
43#include <sys/types.h>
44#include <unistd.h>
45#include <unwind.h>
46
47#if !SANITIZER_ANDROID
48#include <sys/signal.h>
49#endif
50
51// <linux/time.h>
52struct kernel_timeval {
53  long tv_sec;
54  long tv_usec;
55};
56
57// <linux/futex.h> is broken on some linux distributions.
58const int FUTEX_WAIT = 0;
59const int FUTEX_WAKE = 1;
60
61// Are we using 32-bit or 64-bit syscalls?
62// x32 (which defines __x86_64__) has SANITIZER_WORDSIZE == 32
63// but it still needs to use 64-bit syscalls.
64#if defined(__x86_64__) || SANITIZER_WORDSIZE == 64
65# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 1
66#else
67# define SANITIZER_LINUX_USES_64BIT_SYSCALLS 0
68#endif
69
70namespace __sanitizer {
71
72#ifdef __x86_64__
73#include "sanitizer_syscall_linux_x86_64.inc"
74#else
75#include "sanitizer_syscall_generic.inc"
76#endif
77
78// --------------- sanitizer_libc.h
79uptr internal_mmap(void *addr, uptr length, int prot, int flags,
80                    int fd, u64 offset) {
81#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
82  return internal_syscall(__NR_mmap, addr, length, prot, flags, fd, offset);
83#else
84  return internal_syscall(__NR_mmap2, addr, length, prot, flags, fd, offset);
85#endif
86}
87
88uptr internal_munmap(void *addr, uptr length) {
89  return internal_syscall(__NR_munmap, addr, length);
90}
91
92uptr internal_close(fd_t fd) {
93  return internal_syscall(__NR_close, fd);
94}
95
96uptr internal_open(const char *filename, int flags) {
97  return internal_syscall(__NR_open, filename, flags);
98}
99
100uptr internal_open(const char *filename, int flags, u32 mode) {
101  return internal_syscall(__NR_open, filename, flags, mode);
102}
103
104uptr OpenFile(const char *filename, bool write) {
105  return internal_open(filename,
106      write ? O_WRONLY | O_CREAT /*| O_CLOEXEC*/ : O_RDONLY, 0660);
107}
108
109uptr internal_read(fd_t fd, void *buf, uptr count) {
110  sptr res;
111  HANDLE_EINTR(res, (sptr)internal_syscall(__NR_read, fd, buf, count));
112  return res;
113}
114
115uptr internal_write(fd_t fd, const void *buf, uptr count) {
116  sptr res;
117  HANDLE_EINTR(res, (sptr)internal_syscall(__NR_write, fd, buf, count));
118  return res;
119}
120
121#if !SANITIZER_LINUX_USES_64BIT_SYSCALLS
122static void stat64_to_stat(struct stat64 *in, struct stat *out) {
123  internal_memset(out, 0, sizeof(*out));
124  out->st_dev = in->st_dev;
125  out->st_ino = in->st_ino;
126  out->st_mode = in->st_mode;
127  out->st_nlink = in->st_nlink;
128  out->st_uid = in->st_uid;
129  out->st_gid = in->st_gid;
130  out->st_rdev = in->st_rdev;
131  out->st_size = in->st_size;
132  out->st_blksize = in->st_blksize;
133  out->st_blocks = in->st_blocks;
134  out->st_atime = in->st_atime;
135  out->st_mtime = in->st_mtime;
136  out->st_ctime = in->st_ctime;
137  out->st_ino = in->st_ino;
138}
139#endif
140
141uptr internal_stat(const char *path, void *buf) {
142#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
143  return internal_syscall(__NR_stat, path, buf);
144#else
145  struct stat64 buf64;
146  int res = internal_syscall(__NR_stat64, path, &buf64);
147  stat64_to_stat(&buf64, (struct stat *)buf);
148  return res;
149#endif
150}
151
152uptr internal_lstat(const char *path, void *buf) {
153#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
154  return internal_syscall(__NR_lstat, path, buf);
155#else
156  struct stat64 buf64;
157  int res = internal_syscall(__NR_lstat64, path, &buf64);
158  stat64_to_stat(&buf64, (struct stat *)buf);
159  return res;
160#endif
161}
162
163uptr internal_fstat(fd_t fd, void *buf) {
164#if SANITIZER_LINUX_USES_64BIT_SYSCALLS
165  return internal_syscall(__NR_fstat, fd, buf);
166#else
167  struct stat64 buf64;
168  int res = internal_syscall(__NR_fstat64, fd, &buf64);
169  stat64_to_stat(&buf64, (struct stat *)buf);
170  return res;
171#endif
172}
173
174uptr internal_filesize(fd_t fd) {
175  struct stat st;
176  if (internal_fstat(fd, &st))
177    return -1;
178  return (uptr)st.st_size;
179}
180
181uptr internal_dup2(int oldfd, int newfd) {
182  return internal_syscall(__NR_dup2, oldfd, newfd);
183}
184
185uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
186  return internal_syscall(__NR_readlink, path, buf, bufsize);
187}
188
189uptr internal_unlink(const char *path) {
190  return internal_syscall(__NR_unlink, path);
191}
192
193uptr internal_sched_yield() {
194  return internal_syscall(__NR_sched_yield);
195}
196
197void internal__exit(int exitcode) {
198  internal_syscall(__NR_exit_group, exitcode);
199  Die();  // Unreachable.
200}
201
202uptr internal_execve(const char *filename, char *const argv[],
203                     char *const envp[]) {
204  return internal_syscall(__NR_execve, filename, argv, envp);
205}
206
207// ----------------- sanitizer_common.h
208bool FileExists(const char *filename) {
209  struct stat st;
210  if (internal_stat(filename, &st))
211    return false;
212  // Sanity check: filename is a regular file.
213  return S_ISREG(st.st_mode);
214}
215
216uptr GetTid() {
217  return internal_syscall(__NR_gettid);
218}
219
220u64 NanoTime() {
221  kernel_timeval tv = {};
222  internal_syscall(__NR_gettimeofday, &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.
228const 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
254extern "C" {
255  SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
256}
257
258#if !SANITIZER_GO
259static 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
279static 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
296void 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
306void 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  getSymbolizer()->PrepareForSandboxing();
314}
315
316// ----------------- sanitizer_procmaps.h
317// Linker initialized.
318ProcSelfMapsBuff MemoryMappingLayout::cached_proc_self_maps_;
319StaticSpinMutex MemoryMappingLayout::cache_lock_;  // Linker initialized.
320
321MemoryMappingLayout::MemoryMappingLayout(bool cache_enabled) {
322  proc_self_maps_.len =
323      ReadFileToBuffer("/proc/self/maps", &proc_self_maps_.data,
324                       &proc_self_maps_.mmaped_size, 1 << 26);
325  if (cache_enabled) {
326    if (proc_self_maps_.mmaped_size == 0) {
327      LoadFromCache();
328      CHECK_GT(proc_self_maps_.len, 0);
329    }
330  } else {
331    CHECK_GT(proc_self_maps_.mmaped_size, 0);
332  }
333  Reset();
334  // FIXME: in the future we may want to cache the mappings on demand only.
335  if (cache_enabled)
336    CacheMemoryMappings();
337}
338
339MemoryMappingLayout::~MemoryMappingLayout() {
340  // Only unmap the buffer if it is different from the cached one. Otherwise
341  // it will be unmapped when the cache is refreshed.
342  if (proc_self_maps_.data != cached_proc_self_maps_.data) {
343    UnmapOrDie(proc_self_maps_.data, proc_self_maps_.mmaped_size);
344  }
345}
346
347void MemoryMappingLayout::Reset() {
348  current_ = proc_self_maps_.data;
349}
350
351// static
352void MemoryMappingLayout::CacheMemoryMappings() {
353  SpinMutexLock l(&cache_lock_);
354  // Don't invalidate the cache if the mappings are unavailable.
355  ProcSelfMapsBuff old_proc_self_maps;
356  old_proc_self_maps = cached_proc_self_maps_;
357  cached_proc_self_maps_.len =
358      ReadFileToBuffer("/proc/self/maps", &cached_proc_self_maps_.data,
359                       &cached_proc_self_maps_.mmaped_size, 1 << 26);
360  if (cached_proc_self_maps_.mmaped_size == 0) {
361    cached_proc_self_maps_ = old_proc_self_maps;
362  } else {
363    if (old_proc_self_maps.mmaped_size) {
364      UnmapOrDie(old_proc_self_maps.data,
365                 old_proc_self_maps.mmaped_size);
366    }
367  }
368}
369
370void MemoryMappingLayout::LoadFromCache() {
371  SpinMutexLock l(&cache_lock_);
372  if (cached_proc_self_maps_.data) {
373    proc_self_maps_ = cached_proc_self_maps_;
374  }
375}
376
377// Parse a hex value in str and update str.
378static uptr ParseHex(char **str) {
379  uptr x = 0;
380  char *s;
381  for (s = *str; ; s++) {
382    char c = *s;
383    uptr v = 0;
384    if (c >= '0' && c <= '9')
385      v = c - '0';
386    else if (c >= 'a' && c <= 'f')
387      v = c - 'a' + 10;
388    else if (c >= 'A' && c <= 'F')
389      v = c - 'A' + 10;
390    else
391      break;
392    x = x * 16 + v;
393  }
394  *str = s;
395  return x;
396}
397
398static bool IsOneOf(char c, char c1, char c2) {
399  return c == c1 || c == c2;
400}
401
402static bool IsDecimal(char c) {
403  return c >= '0' && c <= '9';
404}
405
406static bool IsHex(char c) {
407  return (c >= '0' && c <= '9')
408      || (c >= 'a' && c <= 'f');
409}
410
411static uptr ReadHex(const char *p) {
412  uptr v = 0;
413  for (; IsHex(p[0]); p++) {
414    if (p[0] >= '0' && p[0] <= '9')
415      v = v * 16 + p[0] - '0';
416    else
417      v = v * 16 + p[0] - 'a' + 10;
418  }
419  return v;
420}
421
422static uptr ReadDecimal(const char *p) {
423  uptr v = 0;
424  for (; IsDecimal(p[0]); p++)
425    v = v * 10 + p[0] - '0';
426  return v;
427}
428
429
430bool MemoryMappingLayout::Next(uptr *start, uptr *end, uptr *offset,
431                               char filename[], uptr filename_size,
432                               uptr *protection) {
433  char *last = proc_self_maps_.data + proc_self_maps_.len;
434  if (current_ >= last) return false;
435  uptr dummy;
436  if (!start) start = &dummy;
437  if (!end) end = &dummy;
438  if (!offset) offset = &dummy;
439  char *next_line = (char*)internal_memchr(current_, '\n', last - current_);
440  if (next_line == 0)
441    next_line = last;
442  // Example: 08048000-08056000 r-xp 00000000 03:0c 64593   /foo/bar
443  *start = ParseHex(&current_);
444  CHECK_EQ(*current_++, '-');
445  *end = ParseHex(&current_);
446  CHECK_EQ(*current_++, ' ');
447  uptr local_protection = 0;
448  CHECK(IsOneOf(*current_, '-', 'r'));
449  if (*current_++ == 'r')
450    local_protection |= kProtectionRead;
451  CHECK(IsOneOf(*current_, '-', 'w'));
452  if (*current_++ == 'w')
453    local_protection |= kProtectionWrite;
454  CHECK(IsOneOf(*current_, '-', 'x'));
455  if (*current_++ == 'x')
456    local_protection |= kProtectionExecute;
457  CHECK(IsOneOf(*current_, 's', 'p'));
458  if (*current_++ == 's')
459    local_protection |= kProtectionShared;
460  if (protection) {
461    *protection = local_protection;
462  }
463  CHECK_EQ(*current_++, ' ');
464  *offset = ParseHex(&current_);
465  CHECK_EQ(*current_++, ' ');
466  ParseHex(&current_);
467  CHECK_EQ(*current_++, ':');
468  ParseHex(&current_);
469  CHECK_EQ(*current_++, ' ');
470  while (IsDecimal(*current_))
471    current_++;
472  // Qemu may lack the trailing space.
473  // http://code.google.com/p/address-sanitizer/issues/detail?id=160
474  // CHECK_EQ(*current_++, ' ');
475  // Skip spaces.
476  while (current_ < next_line && *current_ == ' ')
477    current_++;
478  // Fill in the filename.
479  uptr i = 0;
480  while (current_ < next_line) {
481    if (filename && i < filename_size - 1)
482      filename[i++] = *current_;
483    current_++;
484  }
485  if (filename && i < filename_size)
486    filename[i] = 0;
487  current_ = next_line + 1;
488  return true;
489}
490
491// Gets the object name and the offset by walking MemoryMappingLayout.
492bool MemoryMappingLayout::GetObjectNameAndOffset(uptr addr, uptr *offset,
493                                                 char filename[],
494                                                 uptr filename_size,
495                                                 uptr *protection) {
496  return IterateForObjectNameAndOffset(addr, offset, filename, filename_size,
497                                       protection);
498}
499
500void GetMemoryProfile(fill_profile_f cb, uptr *stats, uptr stats_size) {
501  char *smaps = 0;
502  uptr smaps_cap = 0;
503  uptr smaps_len = ReadFileToBuffer("/proc/self/smaps",
504      &smaps, &smaps_cap, 64<<20);
505  uptr start = 0;
506  bool file = false;
507  const char *pos = smaps;
508  while (pos < smaps + smaps_len) {
509    if (IsHex(pos[0])) {
510      start = ReadHex(pos);
511      for (; *pos != '/' && *pos > '\n'; pos++) {}
512      file = *pos == '/';
513    } else if (internal_strncmp(pos, "Rss:", 4) == 0) {
514      for (; *pos < '0' || *pos > '9'; pos++) {}
515      uptr rss = ReadDecimal(pos) * 1024;
516      cb(start, rss, file, stats, stats_size);
517    }
518    while (*pos++ != '\n') {}
519  }
520  UnmapOrDie(smaps, smaps_cap);
521}
522
523enum MutexState {
524  MtxUnlocked = 0,
525  MtxLocked = 1,
526  MtxSleeping = 2
527};
528
529BlockingMutex::BlockingMutex(LinkerInitialized) {
530  CHECK_EQ(owner_, 0);
531}
532
533BlockingMutex::BlockingMutex() {
534  internal_memset(this, 0, sizeof(*this));
535}
536
537void BlockingMutex::Lock() {
538  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
539  if (atomic_exchange(m, MtxLocked, memory_order_acquire) == MtxUnlocked)
540    return;
541  while (atomic_exchange(m, MtxSleeping, memory_order_acquire) != MtxUnlocked)
542    internal_syscall(__NR_futex, m, FUTEX_WAIT, MtxSleeping, 0, 0, 0);
543}
544
545void BlockingMutex::Unlock() {
546  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
547  u32 v = atomic_exchange(m, MtxUnlocked, memory_order_relaxed);
548  CHECK_NE(v, MtxUnlocked);
549  if (v == MtxSleeping)
550    internal_syscall(__NR_futex, m, FUTEX_WAKE, 1, 0, 0, 0);
551}
552
553void BlockingMutex::CheckLocked() {
554  atomic_uint32_t *m = reinterpret_cast<atomic_uint32_t *>(&opaque_storage_);
555  CHECK_NE(MtxUnlocked, atomic_load(m, memory_order_relaxed));
556}
557
558// ----------------- sanitizer_linux.h
559// The actual size of this structure is specified by d_reclen.
560// Note that getdents64 uses a different structure format. We only provide the
561// 32-bit syscall here.
562struct linux_dirent {
563  unsigned long      d_ino;
564  unsigned long      d_off;
565  unsigned short     d_reclen;
566  char               d_name[256];
567};
568
569// Syscall wrappers.
570uptr internal_ptrace(int request, int pid, void *addr, void *data) {
571  return internal_syscall(__NR_ptrace, request, pid, addr, data);
572}
573
574uptr internal_waitpid(int pid, int *status, int options) {
575  return internal_syscall(__NR_wait4, pid, status, options, 0 /* rusage */);
576}
577
578uptr internal_getpid() {
579  return internal_syscall(__NR_getpid);
580}
581
582uptr internal_getppid() {
583  return internal_syscall(__NR_getppid);
584}
585
586uptr internal_getdents(fd_t fd, struct linux_dirent *dirp, unsigned int count) {
587  return internal_syscall(__NR_getdents, fd, dirp, count);
588}
589
590uptr internal_lseek(fd_t fd, OFF_T offset, int whence) {
591  return internal_syscall(__NR_lseek, fd, offset, whence);
592}
593
594uptr internal_prctl(int option, uptr arg2, uptr arg3, uptr arg4, uptr arg5) {
595  return internal_syscall(__NR_prctl, option, arg2, arg3, arg4, arg5);
596}
597
598uptr internal_sigaltstack(const struct sigaltstack *ss,
599                         struct sigaltstack *oss) {
600  return internal_syscall(__NR_sigaltstack, ss, oss);
601}
602
603// ThreadLister implementation.
604ThreadLister::ThreadLister(int pid)
605  : pid_(pid),
606    descriptor_(-1),
607    buffer_(4096),
608    error_(true),
609    entry_((struct linux_dirent *)buffer_.data()),
610    bytes_read_(0) {
611  char task_directory_path[80];
612  internal_snprintf(task_directory_path, sizeof(task_directory_path),
613                    "/proc/%d/task/", pid);
614  uptr openrv = internal_open(task_directory_path, O_RDONLY | O_DIRECTORY);
615  if (internal_iserror(openrv)) {
616    error_ = true;
617    Report("Can't open /proc/%d/task for reading.\n", pid);
618  } else {
619    error_ = false;
620    descriptor_ = openrv;
621  }
622}
623
624int ThreadLister::GetNextTID() {
625  int tid = -1;
626  do {
627    if (error_)
628      return -1;
629    if ((char *)entry_ >= &buffer_[bytes_read_] && !GetDirectoryEntries())
630      return -1;
631    if (entry_->d_ino != 0 && entry_->d_name[0] >= '0' &&
632        entry_->d_name[0] <= '9') {
633      // Found a valid tid.
634      tid = (int)internal_atoll(entry_->d_name);
635    }
636    entry_ = (struct linux_dirent *)(((char *)entry_) + entry_->d_reclen);
637  } while (tid < 0);
638  return tid;
639}
640
641void ThreadLister::Reset() {
642  if (error_ || descriptor_ < 0)
643    return;
644  internal_lseek(descriptor_, 0, SEEK_SET);
645}
646
647ThreadLister::~ThreadLister() {
648  if (descriptor_ >= 0)
649    internal_close(descriptor_);
650}
651
652bool ThreadLister::error() { return error_; }
653
654bool ThreadLister::GetDirectoryEntries() {
655  CHECK_GE(descriptor_, 0);
656  CHECK_NE(error_, true);
657  bytes_read_ = internal_getdents(descriptor_,
658                                  (struct linux_dirent *)buffer_.data(),
659                                  buffer_.size());
660  if (internal_iserror(bytes_read_)) {
661    Report("Can't read directory entries from /proc/%d/task.\n", pid_);
662    error_ = true;
663    return false;
664  } else if (bytes_read_ == 0) {
665    return false;
666  }
667  entry_ = (struct linux_dirent *)buffer_.data();
668  return true;
669}
670
671uptr GetPageSize() {
672#if defined(__x86_64__) || defined(__i386__)
673  return EXEC_PAGESIZE;
674#else
675  return sysconf(_SC_PAGESIZE);  // EXEC_PAGESIZE may not be trustworthy.
676#endif
677}
678
679static char proc_self_exe_cache_str[kMaxPathLength];
680static uptr proc_self_exe_cache_len = 0;
681
682uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
683  uptr module_name_len = internal_readlink(
684      "/proc/self/exe", buf, buf_len);
685  int readlink_error;
686  if (internal_iserror(buf_len, &readlink_error)) {
687    if (proc_self_exe_cache_len) {
688      // If available, use the cached module name.
689      CHECK_LE(proc_self_exe_cache_len, buf_len);
690      internal_strncpy(buf, proc_self_exe_cache_str, buf_len);
691      module_name_len = internal_strlen(proc_self_exe_cache_str);
692    } else {
693      // We can't read /proc/self/exe for some reason, assume the name of the
694      // binary is unknown.
695      Report("WARNING: readlink(\"/proc/self/exe\") failed with errno %d, "
696             "some stack frames may not be symbolized\n", readlink_error);
697      module_name_len = internal_snprintf(buf, buf_len, "/proc/self/exe");
698    }
699    CHECK_LT(module_name_len, buf_len);
700    buf[module_name_len] = '\0';
701  }
702  return module_name_len;
703}
704
705void CacheBinaryName() {
706  if (!proc_self_exe_cache_len) {
707    proc_self_exe_cache_len =
708        ReadBinaryName(proc_self_exe_cache_str, kMaxPathLength);
709  }
710}
711
712// Match full names of the form /path/to/base_name{-,.}*
713bool LibraryNameIs(const char *full_name, const char *base_name) {
714  const char *name = full_name;
715  // Strip path.
716  while (*name != '\0') name++;
717  while (name > full_name && *name != '/') name--;
718  if (*name == '/') name++;
719  uptr base_name_length = internal_strlen(base_name);
720  if (internal_strncmp(name, base_name, base_name_length)) return false;
721  return (name[base_name_length] == '-' || name[base_name_length] == '.');
722}
723
724#if !SANITIZER_ANDROID
725// Call cb for each region mapped by map.
726void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
727  typedef ElfW(Phdr) Elf_Phdr;
728  typedef ElfW(Ehdr) Elf_Ehdr;
729  char *base = (char *)map->l_addr;
730  Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
731  char *phdrs = base + ehdr->e_phoff;
732  char *phdrs_end = phdrs + ehdr->e_phnum * ehdr->e_phentsize;
733
734  // Find the segment with the minimum base so we can "relocate" the p_vaddr
735  // fields.  Typically ET_DYN objects (DSOs) have base of zero and ET_EXEC
736  // objects have a non-zero base.
737  uptr preferred_base = (uptr)-1;
738  for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
739    Elf_Phdr *phdr = (Elf_Phdr *)iter;
740    if (phdr->p_type == PT_LOAD && preferred_base > (uptr)phdr->p_vaddr)
741      preferred_base = (uptr)phdr->p_vaddr;
742  }
743
744  // Compute the delta from the real base to get a relocation delta.
745  sptr delta = (uptr)base - preferred_base;
746  // Now we can figure out what the loader really mapped.
747  for (char *iter = phdrs; iter != phdrs_end; iter += ehdr->e_phentsize) {
748    Elf_Phdr *phdr = (Elf_Phdr *)iter;
749    if (phdr->p_type == PT_LOAD) {
750      uptr seg_start = phdr->p_vaddr + delta;
751      uptr seg_end = seg_start + phdr->p_memsz;
752      // None of these values are aligned.  We consider the ragged edges of the
753      // load command as defined, since they are mapped from the file.
754      seg_start = RoundDownTo(seg_start, GetPageSizeCached());
755      seg_end = RoundUpTo(seg_end, GetPageSizeCached());
756      cb((void *)seg_start, seg_end - seg_start);
757    }
758  }
759}
760#endif
761
762#if defined(__x86_64__)
763// We cannot use glibc's clone wrapper, because it messes with the child
764// task's TLS. It writes the PID and TID of the child task to its thread
765// descriptor, but in our case the child task shares the thread descriptor with
766// the parent (because we don't know how to allocate a new thread
767// descriptor to keep glibc happy). So the stock version of clone(), when
768// used with CLONE_VM, would end up corrupting the parent's thread descriptor.
769uptr internal_clone(int (*fn)(void *), void *child_stack, int flags, void *arg,
770                    int *parent_tidptr, void *newtls, int *child_tidptr) {
771  long long res;
772  if (!fn || !child_stack)
773    return -EINVAL;
774  CHECK_EQ(0, (uptr)child_stack % 16);
775  child_stack = (char *)child_stack - 2 * sizeof(void *);
776  ((void **)child_stack)[0] = (void *)(uptr)fn;
777  ((void **)child_stack)[1] = arg;
778  __asm__ __volatile__(
779                       /* %rax = syscall(%rax = __NR_clone,
780                        *                %rdi = flags,
781                        *                %rsi = child_stack,
782                        *                %rdx = parent_tidptr,
783                        *                %r8  = new_tls,
784                        *                %r10 = child_tidptr)
785                        */
786                       "movq   %6,%%r8\n"
787                       "movq   %7,%%r10\n"
788                       ".cfi_endproc\n"
789                       "syscall\n"
790
791                       /* if (%rax != 0)
792                        *   return;
793                        */
794                       "testq  %%rax,%%rax\n"
795                       "jnz    1f\n"
796
797                       /* In the child. Terminate unwind chain. */
798                       ".cfi_startproc\n"
799                       ".cfi_undefined %%rip;\n"
800                       "xorq   %%rbp,%%rbp\n"
801
802                       /* Call "fn(arg)". */
803                       "popq   %%rax\n"
804                       "popq   %%rdi\n"
805                       "call   *%%rax\n"
806
807                       /* Call _exit(%rax). */
808                       "movq   %%rax,%%rdi\n"
809                       "movq   %2,%%rax\n"
810                       "syscall\n"
811
812                       /* Return to parent. */
813                     "1:\n"
814                       : "=a" (res)
815                       : "a"(__NR_clone), "i"(__NR_exit),
816                         "S"(child_stack),
817                         "D"(flags),
818                         "d"(parent_tidptr),
819                         "r"(newtls),
820                         "r"(child_tidptr)
821                       : "rsp", "memory", "r8", "r10", "r11", "rcx");
822  return res;
823}
824#endif  // defined(__x86_64__)
825}  // namespace __sanitizer
826
827#endif  // SANITIZER_LINUX
828