sanitizer_linux_libcdep.cc revision 1adf52b7a65a9556fdf649869a63ad4379a91fa7 
1//===-- sanitizer_linux_libcdep.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_procmaps.h"
20#include "sanitizer_stacktrace.h"
21
22#include <dlfcn.h>
23#include <pthread.h>
24#include <sys/prctl.h>
25#include <sys/resource.h>
26#include <unwind.h>
27
28namespace __sanitizer {
29
30void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
31                                uptr *stack_bottom) {
32  static const uptr kMaxThreadStackSize = 256 * (1 << 20);  // 256M
33  CHECK(stack_top);
34  CHECK(stack_bottom);
35  if (at_initialization) {
36    // This is the main thread. Libpthread may not be initialized yet.
37    struct rlimit rl;
38    CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
39
40    // Find the mapping that contains a stack variable.
41    MemoryMappingLayout proc_maps(/*cache_enabled*/true);
42    uptr start, end, offset;
43    uptr prev_end = 0;
44    while (proc_maps.Next(&start, &end, &offset, 0, 0, /* protection */0)) {
45      if ((uptr)&rl < end)
46        break;
47      prev_end = end;
48    }
49    CHECK((uptr)&rl >= start && (uptr)&rl < end);
50
51    // Get stacksize from rlimit, but clip it so that it does not overlap
52    // with other mappings.
53    uptr stacksize = rl.rlim_cur;
54    if (stacksize > end - prev_end)
55      stacksize = end - prev_end;
56    // When running with unlimited stack size, we still want to set some limit.
57    // The unlimited stack size is caused by 'ulimit -s unlimited'.
58    // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
59    if (stacksize > kMaxThreadStackSize)
60      stacksize = kMaxThreadStackSize;
61    *stack_top = end;
62    *stack_bottom = end - stacksize;
63    return;
64  }
65  pthread_attr_t attr;
66  pthread_attr_init(&attr);
67  CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
68  uptr stacksize = 0;
69  void *stackaddr = 0;
70  pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
71  pthread_attr_destroy(&attr);
72
73  *stack_top = (uptr)stackaddr + stacksize;
74  *stack_bottom = (uptr)stackaddr;
75  CHECK(stacksize < kMaxThreadStackSize);  // Sanity check.
76}
77
78// Does not compile for Go because dlsym() requires -ldl
79#ifndef SANITIZER_GO
80bool SetEnv(const char *name, const char *value) {
81  void *f = dlsym(RTLD_NEXT, "setenv");
82  if (f == 0)
83    return false;
84  typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
85  setenv_ft setenv_f;
86  CHECK_EQ(sizeof(setenv_f), sizeof(f));
87  internal_memcpy(&setenv_f, &f, sizeof(f));
88  return setenv_f(name, value, 1) == 0;
89}
90#endif
91
92bool SanitizerSetThreadName(const char *name) {
93#ifdef PR_SET_NAME
94  return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0);  // NOLINT
95#else
96  return false;
97#endif
98}
99
100bool SanitizerGetThreadName(char *name, int max_len) {
101#ifdef PR_GET_NAME
102  char buff[17];
103  if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
104    return false;
105  internal_strncpy(name, buff, max_len);
106  name[max_len] = 0;
107  return true;
108#else
109  return false;
110#endif
111}
112
113#ifndef SANITIZER_GO
114//------------------------- SlowUnwindStack -----------------------------------
115#ifdef __arm__
116#define UNWIND_STOP _URC_END_OF_STACK
117#define UNWIND_CONTINUE _URC_NO_REASON
118#else
119#define UNWIND_STOP _URC_NORMAL_STOP
120#define UNWIND_CONTINUE _URC_NO_REASON
121#endif
122
123uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
124#ifdef __arm__
125  uptr val;
126  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
127      15 /* r15 = PC */, _UVRSD_UINT32, &val);
128  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
129  // Clear the Thumb bit.
130  return val & ~(uptr)1;
131#else
132  return _Unwind_GetIP(ctx);
133#endif
134}
135
136_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
137  StackTrace *b = (StackTrace*)param;
138  CHECK(b->size < b->max_size);
139  uptr pc = Unwind_GetIP(ctx);
140  b->trace[b->size++] = pc;
141  if (b->size == b->max_size) return UNWIND_STOP;
142  return UNWIND_CONTINUE;
143}
144
145static bool MatchPc(uptr cur_pc, uptr trace_pc) {
146  return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
147}
148
149void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
150  this->size = 0;
151  this->max_size = max_depth;
152  if (max_depth > 1) {
153    _Unwind_Backtrace(Unwind_Trace, this);
154    // We need to pop a few frames so that pc is on top.
155    // trace[0] belongs to the current function so we always pop it.
156    int to_pop = 1;
157    /**/ if (size > 1 && MatchPc(pc, trace[1])) to_pop = 1;
158    else if (size > 2 && MatchPc(pc, trace[2])) to_pop = 2;
159    else if (size > 3 && MatchPc(pc, trace[3])) to_pop = 3;
160    else if (size > 4 && MatchPc(pc, trace[4])) to_pop = 4;
161    else if (size > 5 && MatchPc(pc, trace[5])) to_pop = 5;
162    this->PopStackFrames(to_pop);
163  }
164  this->trace[0] = pc;
165}
166
167#endif  // !SANITIZER_GO
168
169static uptr g_tls_size;
170
171#ifdef __i386__
172# define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
173#else
174# define DL_INTERNAL_FUNCTION
175#endif
176
177void InitTlsSize() {
178#if !defined(SANITIZER_GO) && !SANITIZER_ANDROID
179  typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
180  get_tls_func get_tls;
181  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
182  CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
183  internal_memcpy(&get_tls, &get_tls_static_info_ptr,
184                  sizeof(get_tls_static_info_ptr));
185  CHECK_NE(get_tls, 0);
186  size_t tls_size = 0;
187  size_t tls_align = 0;
188  get_tls(&tls_size, &tls_align);
189  g_tls_size = tls_size;
190#endif
191}
192
193uptr GetTlsSize() {
194  return g_tls_size;
195}
196
197#if defined(__x86_64__) || defined(__i386__)
198// sizeof(struct thread) from glibc.
199// There has been a report of this being different on glibc 2.11. We don't know
200// when this change happened, so 2.12 is a conservative estimate.
201#if __GLIBC_PREREQ(2, 12)
202const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1216, 2304);
203#else
204const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1168, 2304);
205#endif
206
207uptr ThreadDescriptorSize() {
208  return kThreadDescriptorSize;
209}
210
211// The offset at which pointer to self is located in the thread descriptor.
212const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
213
214uptr ThreadSelfOffset() {
215  return kThreadSelfOffset;
216}
217
218uptr ThreadSelf() {
219  uptr descr_addr;
220#ifdef __i386__
221  asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
222#else
223  asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
224#endif
225  return descr_addr;
226}
227#endif  // defined(__x86_64__) || defined(__i386__)
228
229void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
230                          uptr *tls_addr, uptr *tls_size) {
231#ifndef SANITIZER_GO
232#if defined(__x86_64__) || defined(__i386__)
233  *tls_addr = ThreadSelf();
234  *tls_size = GetTlsSize();
235  *tls_addr -= *tls_size;
236  *tls_addr += kThreadDescriptorSize;
237#else
238  *tls_addr = 0;
239  *tls_size = 0;
240#endif
241
242  uptr stack_top, stack_bottom;
243  GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
244  *stk_addr = stack_bottom;
245  *stk_size = stack_top - stack_bottom;
246
247  if (!main) {
248    // If stack and tls intersect, make them non-intersecting.
249    if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
250      CHECK_GT(*tls_addr + *tls_size, *stk_addr);
251      CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
252      *stk_size -= *tls_size;
253      *tls_addr = *stk_addr + *stk_size;
254    }
255  }
256#else  // SANITIZER_GO
257  *stk_addr = 0;
258  *stk_size = 0;
259  *tls_addr = 0;
260  *tls_size = 0;
261#endif  // SANITIZER_GO
262}
263
264void AdjustStackSizeLinux(void *attr_, int verbosity) {
265  pthread_attr_t *attr = (pthread_attr_t *)attr_;
266  uptr stackaddr = 0;
267  size_t stacksize = 0;
268  pthread_attr_getstack(attr, (void**)&stackaddr, &stacksize);
269  // GLibC will return (0 - stacksize) as the stack address in the case when
270  // stacksize is set, but stackaddr is not.
271  bool stack_set = (stackaddr != 0) && (stackaddr + stacksize != 0);
272  // We place a lot of tool data into TLS, account for that.
273  const uptr minstacksize = GetTlsSize() + 128*1024;
274  if (stacksize < minstacksize) {
275    if (!stack_set) {
276      if (verbosity && stacksize != 0)
277        Printf("Sanitizer: increasing stacksize %zu->%zu\n", stacksize,
278               minstacksize);
279      pthread_attr_setstacksize(attr, minstacksize);
280    } else {
281      Printf("Sanitizer: pre-allocated stack size is insufficient: "
282             "%zu < %zu\n", stacksize, minstacksize);
283      Printf("Sanitizer: pthread_create is likely to fail.\n");
284    }
285  }
286}
287
288}  // namespace __sanitizer
289
290#endif  // SANITIZER_LINUX
291