asan_linux.cc revision 996651d09e56caa91ffcc33bf1a13a283cfcd5e2 
1//===-- asan_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 AddressSanitizer, an address sanity checker.
11//
12// Linux-specific details.
13//===----------------------------------------------------------------------===//
14#ifdef __linux__
15
16#include "asan_interceptors.h"
17#include "asan_internal.h"
18#include "asan_lock.h"
19#include "asan_thread.h"
20#include "sanitizer_common/sanitizer_libc.h"
21#include "sanitizer_common/sanitizer_procmaps.h"
22
23#include <sys/time.h>
24#include <sys/resource.h>
25#include <sys/mman.h>
26#include <sys/syscall.h>
27#include <sys/types.h>
28#include <fcntl.h>
29#include <pthread.h>
30#include <stdio.h>
31#include <unistd.h>
32#include <unwind.h>
33
34#ifndef ANDROID
35// FIXME: where to get ucontext on Android?
36#include <sys/ucontext.h>
37#endif
38
39extern "C" void* _DYNAMIC;
40
41namespace __asan {
42
43void *AsanDoesNotSupportStaticLinkage() {
44  // This will fail to link with -static.
45  return &_DYNAMIC;  // defined in link.h
46}
47
48void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
49#ifdef ANDROID
50  *pc = *sp = *bp = 0;
51#elif defined(__arm__)
52  ucontext_t *ucontext = (ucontext_t*)context;
53  *pc = ucontext->uc_mcontext.arm_pc;
54  *bp = ucontext->uc_mcontext.arm_fp;
55  *sp = ucontext->uc_mcontext.arm_sp;
56# elif defined(__x86_64__)
57  ucontext_t *ucontext = (ucontext_t*)context;
58  *pc = ucontext->uc_mcontext.gregs[REG_RIP];
59  *bp = ucontext->uc_mcontext.gregs[REG_RBP];
60  *sp = ucontext->uc_mcontext.gregs[REG_RSP];
61# elif defined(__i386__)
62  ucontext_t *ucontext = (ucontext_t*)context;
63  *pc = ucontext->uc_mcontext.gregs[REG_EIP];
64  *bp = ucontext->uc_mcontext.gregs[REG_EBP];
65  *sp = ucontext->uc_mcontext.gregs[REG_ESP];
66#else
67# error "Unsupported arch"
68#endif
69}
70
71bool AsanInterceptsSignal(int signum) {
72  return signum == SIGSEGV && FLAG_handle_segv;
73}
74
75void *AsanMmapFixedNoReserve(uptr fixed_addr, uptr size) {
76  return internal_mmap((void*)fixed_addr, size,
77                      PROT_READ | PROT_WRITE,
78                      MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE,
79                      0, 0);
80}
81
82void *AsanMprotect(uptr fixed_addr, uptr size) {
83  return internal_mmap((void*)fixed_addr, size,
84                       PROT_NONE,
85                       MAP_PRIVATE | MAP_ANON | MAP_FIXED | MAP_NORESERVE,
86                       0, 0);
87}
88
89// Like getenv, but reads env directly from /proc and does not use libc.
90// This function should be called first inside __asan_init.
91const char* AsanGetEnv(const char* name) {
92  static char *environ;
93  static uptr len;
94  static bool inited;
95  if (!inited) {
96    inited = true;
97    uptr environ_size;
98    len = ReadFileToBuffer("/proc/self/environ",
99                           &environ, &environ_size, 1 << 26);
100  }
101  if (!environ || len == 0) return 0;
102  uptr namelen = internal_strlen(name);
103  const char *p = environ;
104  while (*p != '\0') {  // will happen at the \0\0 that terminates the buffer
105    // proc file has the format NAME=value\0NAME=value\0NAME=value\0...
106    const char* endp =
107        (char*)internal_memchr(p, '\0', len - (p - environ));
108    if (endp == 0)  // this entry isn't NUL terminated
109      return 0;
110    else if (!internal_memcmp(p, name, namelen) && p[namelen] == '=')  // Match.
111      return p + namelen + 1;  // point after =
112    p = endp + 1;
113  }
114  return 0;  // Not found.
115}
116
117AsanLock::AsanLock(LinkerInitialized) {
118  // We assume that pthread_mutex_t initialized to all zeroes is a valid
119  // unlocked mutex. We can not use PTHREAD_MUTEX_INITIALIZER as it triggers
120  // a gcc warning:
121  // extended initializer lists only available with -std=c++0x or -std=gnu++0x
122}
123
124void AsanLock::Lock() {
125  CHECK(sizeof(pthread_mutex_t) <= sizeof(opaque_storage_));
126  pthread_mutex_lock((pthread_mutex_t*)&opaque_storage_);
127  CHECK(!owner_);
128  owner_ = (uptr)pthread_self();
129}
130
131void AsanLock::Unlock() {
132  CHECK(owner_ == (uptr)pthread_self());
133  owner_ = 0;
134  pthread_mutex_unlock((pthread_mutex_t*)&opaque_storage_);
135}
136
137#ifdef __arm__
138#define UNWIND_STOP _URC_END_OF_STACK
139#define UNWIND_CONTINUE _URC_NO_REASON
140#else
141#define UNWIND_STOP _URC_NORMAL_STOP
142#define UNWIND_CONTINUE _URC_NO_REASON
143#endif
144
145uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
146#ifdef __arm__
147  uptr val;
148  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
149      15 /* r15 = PC */, _UVRSD_UINT32, &val);
150  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
151  // Clear the Thumb bit.
152  return val & ~(uptr)1;
153#else
154  return _Unwind_GetIP(ctx);
155#endif
156}
157
158_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx,
159    void *param) {
160  AsanStackTrace *b = (AsanStackTrace*)param;
161  CHECK(b->size < b->max_size);
162  uptr pc = Unwind_GetIP(ctx);
163  b->trace[b->size++] = pc;
164  if (b->size == b->max_size) return UNWIND_STOP;
165  return UNWIND_CONTINUE;
166}
167
168void AsanStackTrace::GetStackTrace(uptr max_s, uptr pc, uptr bp) {
169  size = 0;
170  trace[0] = pc;
171  if ((max_s) > 1) {
172    max_size = max_s;
173#ifdef __arm__
174    _Unwind_Backtrace(Unwind_Trace, this);
175#else
176     FastUnwindStack(pc, bp);
177#endif
178  }
179}
180
181}  // namespace __asan
182
183#endif  // __linux__
184