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
28 namespace __sanitizer {
29
GetThreadStackTopAndBottom(bool at_initialization,uptr * stack_top,uptr * stack_bottom)30 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
31 uptr *stack_bottom) {
32 static const uptr kMaxThreadStackSize = 1 << 30; // 1Gb
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 CHECK_LE(stacksize, kMaxThreadStackSize); // Sanity check.
74 *stack_top = (uptr)stackaddr + stacksize;
75 *stack_bottom = (uptr)stackaddr;
76 }
77
78 // Does not compile for Go because dlsym() requires -ldl
79 #ifndef SANITIZER_GO
SetEnv(const char * name,const char * value)80 bool 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
SanitizerSetThreadName(const char * name)92 bool 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
SanitizerGetThreadName(char * name,int max_len)100 bool 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
Unwind_GetIP(struct _Unwind_Context * ctx)123 uptr 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
Unwind_Trace(struct _Unwind_Context * ctx,void * param)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
MatchPc(uptr cur_pc,uptr trace_pc)145 static bool MatchPc(uptr cur_pc, uptr trace_pc) {
146 return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
147 }
148
SlowUnwindStack(uptr pc,uptr max_depth)149 void 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
169 static 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
InitTlsSize()177 void 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
GetTlsSize()193 uptr 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)
202 const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1216, 2304);
203 #else
204 const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1168, 2304);
205 #endif
206
ThreadDescriptorSize()207 uptr ThreadDescriptorSize() {
208 return kThreadDescriptorSize;
209 }
210
211 // The offset at which pointer to self is located in the thread descriptor.
212 const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
213
ThreadSelfOffset()214 uptr ThreadSelfOffset() {
215 return kThreadSelfOffset;
216 }
217
ThreadSelf()218 uptr 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
GetThreadStackAndTls(bool main,uptr * stk_addr,uptr * stk_size,uptr * tls_addr,uptr * tls_size)229 void 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
AdjustStackSizeLinux(void * attr_,int verbosity)264 void 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