1 //===-- sanitizer_linux_libcdep.cpp ---------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries and implements linux-specific functions from
11 // sanitizer_libc.h.
12 //===----------------------------------------------------------------------===//
13 
14 #include "sanitizer_platform.h"
15 
16 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||                \
17     SANITIZER_OPENBSD || SANITIZER_SOLARIS
18 
19 #include "sanitizer_allocator_internal.h"
20 #include "sanitizer_atomic.h"
21 #include "sanitizer_common.h"
22 #include "sanitizer_file.h"
23 #include "sanitizer_flags.h"
24 #include "sanitizer_freebsd.h"
25 #include "sanitizer_getauxval.h"
26 #include "sanitizer_glibc_version.h"
27 #include "sanitizer_linux.h"
28 #include "sanitizer_placement_new.h"
29 #include "sanitizer_procmaps.h"
30 
31 #include <dlfcn.h>  // for dlsym()
32 #include <link.h>
33 #include <pthread.h>
34 #include <signal.h>
35 #include <sys/resource.h>
36 #include <syslog.h>
37 
38 #if !defined(ElfW)
39 #define ElfW(type) Elf_##type
40 #endif
41 
42 #if SANITIZER_FREEBSD
43 #include <pthread_np.h>
44 #include <osreldate.h>
45 #include <sys/sysctl.h>
46 #define pthread_getattr_np pthread_attr_get_np
47 #endif
48 
49 #if SANITIZER_OPENBSD
50 #include <pthread_np.h>
51 #include <sys/sysctl.h>
52 #endif
53 
54 #if SANITIZER_NETBSD
55 #include <sys/sysctl.h>
56 #include <sys/tls.h>
57 #include <lwp.h>
58 #endif
59 
60 #if SANITIZER_SOLARIS
61 #include <stdlib.h>
62 #include <thread.h>
63 #endif
64 
65 #if SANITIZER_ANDROID
66 #include <android/api-level.h>
67 #if !defined(CPU_COUNT) && !defined(__aarch64__)
68 #include <dirent.h>
69 #include <fcntl.h>
70 struct __sanitizer::linux_dirent {
71   long           d_ino;
72   off_t          d_off;
73   unsigned short d_reclen;
74   char           d_name[];
75 };
76 #endif
77 #endif
78 
79 #if !SANITIZER_ANDROID
80 #include <elf.h>
81 #include <unistd.h>
82 #endif
83 
84 namespace __sanitizer {
85 
86 SANITIZER_WEAK_ATTRIBUTE int
87 real_sigaction(int signum, const void *act, void *oldact);
88 
89 int internal_sigaction(int signum, const void *act, void *oldact) {
90 #if !SANITIZER_GO
91   if (&real_sigaction)
92     return real_sigaction(signum, act, oldact);
93 #endif
94   return sigaction(signum, (const struct sigaction *)act,
95                    (struct sigaction *)oldact);
96 }
97 
98 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
99                                 uptr *stack_bottom) {
100   CHECK(stack_top);
101   CHECK(stack_bottom);
102   if (at_initialization) {
103     // This is the main thread. Libpthread may not be initialized yet.
104     struct rlimit rl;
105     CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
106 
107     // Find the mapping that contains a stack variable.
108     MemoryMappingLayout proc_maps(/*cache_enabled*/true);
109     if (proc_maps.Error()) {
110       *stack_top = *stack_bottom = 0;
111       return;
112     }
113     MemoryMappedSegment segment;
114     uptr prev_end = 0;
115     while (proc_maps.Next(&segment)) {
116       if ((uptr)&rl < segment.end) break;
117       prev_end = segment.end;
118     }
119     CHECK((uptr)&rl >= segment.start && (uptr)&rl < segment.end);
120 
121     // Get stacksize from rlimit, but clip it so that it does not overlap
122     // with other mappings.
123     uptr stacksize = rl.rlim_cur;
124     if (stacksize > segment.end - prev_end) stacksize = segment.end - prev_end;
125     // When running with unlimited stack size, we still want to set some limit.
126     // The unlimited stack size is caused by 'ulimit -s unlimited'.
127     // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
128     if (stacksize > kMaxThreadStackSize)
129       stacksize = kMaxThreadStackSize;
130     *stack_top = segment.end;
131     *stack_bottom = segment.end - stacksize;
132     return;
133   }
134   uptr stacksize = 0;
135   void *stackaddr = nullptr;
136 #if SANITIZER_SOLARIS
137   stack_t ss;
138   CHECK_EQ(thr_stksegment(&ss), 0);
139   stacksize = ss.ss_size;
140   stackaddr = (char *)ss.ss_sp - stacksize;
141 #elif SANITIZER_OPENBSD
142   stack_t sattr;
143   CHECK_EQ(pthread_stackseg_np(pthread_self(), &sattr), 0);
144   stackaddr = sattr.ss_sp;
145   stacksize = sattr.ss_size;
146 #else  // !SANITIZER_SOLARIS
147   pthread_attr_t attr;
148   pthread_attr_init(&attr);
149   CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
150   my_pthread_attr_getstack(&attr, &stackaddr, &stacksize);
151   pthread_attr_destroy(&attr);
152 #endif // SANITIZER_SOLARIS
153 
154   *stack_top = (uptr)stackaddr + stacksize;
155   *stack_bottom = (uptr)stackaddr;
156 }
157 
158 #if !SANITIZER_GO
159 bool SetEnv(const char *name, const char *value) {
160   void *f = dlsym(RTLD_NEXT, "setenv");
161   if (!f)
162     return false;
163   typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
164   setenv_ft setenv_f;
165   CHECK_EQ(sizeof(setenv_f), sizeof(f));
166   internal_memcpy(&setenv_f, &f, sizeof(f));
167   return setenv_f(name, value, 1) == 0;
168 }
169 #endif
170 
171 __attribute__((unused)) static bool GetLibcVersion(int *major, int *minor,
172                                                    int *patch) {
173 #ifdef _CS_GNU_LIBC_VERSION
174   char buf[64];
175   uptr len = confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
176   if (len >= sizeof(buf))
177     return false;
178   buf[len] = 0;
179   static const char kGLibC[] = "glibc ";
180   if (internal_strncmp(buf, kGLibC, sizeof(kGLibC) - 1) != 0)
181     return false;
182   const char *p = buf + sizeof(kGLibC) - 1;
183   *major = internal_simple_strtoll(p, &p, 10);
184   *minor = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
185   *patch = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
186   return true;
187 #else
188   return false;
189 #endif
190 }
191 
192 #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&               \
193     !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_SOLARIS
194 static uptr g_tls_size;
195 
196 #ifdef __i386__
197 # define CHECK_GET_TLS_STATIC_INFO_VERSION (!__GLIBC_PREREQ(2, 27))
198 #else
199 # define CHECK_GET_TLS_STATIC_INFO_VERSION 0
200 #endif
201 
202 #if CHECK_GET_TLS_STATIC_INFO_VERSION
203 # define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
204 #else
205 # define DL_INTERNAL_FUNCTION
206 #endif
207 
208 namespace {
209 struct GetTlsStaticInfoCall {
210   typedef void (*get_tls_func)(size_t*, size_t*);
211 };
212 struct GetTlsStaticInfoRegparmCall {
213   typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
214 };
215 
216 template <typename T>
217 void CallGetTls(void* ptr, size_t* size, size_t* align) {
218   typename T::get_tls_func get_tls;
219   CHECK_EQ(sizeof(get_tls), sizeof(ptr));
220   internal_memcpy(&get_tls, &ptr, sizeof(ptr));
221   CHECK_NE(get_tls, 0);
222   get_tls(size, align);
223 }
224 
225 bool CmpLibcVersion(int major, int minor, int patch) {
226   int ma;
227   int mi;
228   int pa;
229   if (!GetLibcVersion(&ma, &mi, &pa))
230     return false;
231   if (ma > major)
232     return true;
233   if (ma < major)
234     return false;
235   if (mi > minor)
236     return true;
237   if (mi < minor)
238     return false;
239   return pa >= patch;
240 }
241 
242 }  // namespace
243 
244 void InitTlsSize() {
245   // all current supported platforms have 16 bytes stack alignment
246   const size_t kStackAlign = 16;
247   void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
248   size_t tls_size = 0;
249   size_t tls_align = 0;
250   // On i?86, _dl_get_tls_static_info used to be internal_function, i.e.
251   // __attribute__((regparm(3), stdcall)) before glibc 2.27 and is normal
252   // function in 2.27 and later.
253   if (CHECK_GET_TLS_STATIC_INFO_VERSION && !CmpLibcVersion(2, 27, 0))
254     CallGetTls<GetTlsStaticInfoRegparmCall>(get_tls_static_info_ptr,
255                                             &tls_size, &tls_align);
256   else
257     CallGetTls<GetTlsStaticInfoCall>(get_tls_static_info_ptr,
258                                      &tls_size, &tls_align);
259   if (tls_align < kStackAlign)
260     tls_align = kStackAlign;
261   g_tls_size = RoundUpTo(tls_size, tls_align);
262 }
263 #else
264 void InitTlsSize() { }
265 #endif  // !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO &&
266         // !SANITIZER_NETBSD && !SANITIZER_SOLARIS
267 
268 #if (defined(__x86_64__) || defined(__i386__) || defined(__mips__) ||          \
269      defined(__aarch64__) || defined(__powerpc64__) || defined(__s390__) ||    \
270      defined(__arm__)) &&                                                      \
271     SANITIZER_LINUX && !SANITIZER_ANDROID
272 // sizeof(struct pthread) from glibc.
273 static atomic_uintptr_t thread_descriptor_size;
274 
275 uptr ThreadDescriptorSize() {
276   uptr val = atomic_load_relaxed(&thread_descriptor_size);
277   if (val)
278     return val;
279 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
280   int major;
281   int minor;
282   int patch;
283   if (GetLibcVersion(&major, &minor, &patch) && major == 2) {
284     /* sizeof(struct pthread) values from various glibc versions.  */
285     if (SANITIZER_X32)
286       val = 1728; // Assume only one particular version for x32.
287     // For ARM sizeof(struct pthread) changed in Glibc 2.23.
288     else if (SANITIZER_ARM)
289       val = minor <= 22 ? 1120 : 1216;
290     else if (minor <= 3)
291       val = FIRST_32_SECOND_64(1104, 1696);
292     else if (minor == 4)
293       val = FIRST_32_SECOND_64(1120, 1728);
294     else if (minor == 5)
295       val = FIRST_32_SECOND_64(1136, 1728);
296     else if (minor <= 9)
297       val = FIRST_32_SECOND_64(1136, 1712);
298     else if (minor == 10)
299       val = FIRST_32_SECOND_64(1168, 1776);
300     else if (minor == 11 || (minor == 12 && patch == 1))
301       val = FIRST_32_SECOND_64(1168, 2288);
302     else if (minor <= 14)
303       val = FIRST_32_SECOND_64(1168, 2304);
304     else
305       val = FIRST_32_SECOND_64(1216, 2304);
306   }
307 #elif defined(__mips__)
308   // TODO(sagarthakur): add more values as per different glibc versions.
309   val = FIRST_32_SECOND_64(1152, 1776);
310 #elif defined(__aarch64__)
311   // The sizeof (struct pthread) is the same from GLIBC 2.17 to 2.22.
312   val = 1776;
313 #elif defined(__powerpc64__)
314   val = 1776; // from glibc.ppc64le 2.20-8.fc21
315 #elif defined(__s390__)
316   val = FIRST_32_SECOND_64(1152, 1776); // valid for glibc 2.22
317 #endif
318   if (val)
319     atomic_store_relaxed(&thread_descriptor_size, val);
320   return val;
321 }
322 
323 // The offset at which pointer to self is located in the thread descriptor.
324 const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);
325 
326 uptr ThreadSelfOffset() {
327   return kThreadSelfOffset;
328 }
329 
330 #if defined(__mips__) || defined(__powerpc64__)
331 // TlsPreTcbSize includes size of struct pthread_descr and size of tcb
332 // head structure. It lies before the static tls blocks.
333 static uptr TlsPreTcbSize() {
334 # if defined(__mips__)
335   const uptr kTcbHead = 16; // sizeof (tcbhead_t)
336 # elif defined(__powerpc64__)
337   const uptr kTcbHead = 88; // sizeof (tcbhead_t)
338 # endif
339   const uptr kTlsAlign = 16;
340   const uptr kTlsPreTcbSize =
341       RoundUpTo(ThreadDescriptorSize() + kTcbHead, kTlsAlign);
342   return kTlsPreTcbSize;
343 }
344 #endif
345 
346 uptr ThreadSelf() {
347   uptr descr_addr;
348 # if defined(__i386__)
349   asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
350 # elif defined(__x86_64__)
351   asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
352 # elif defined(__mips__)
353   // MIPS uses TLS variant I. The thread pointer (in hardware register $29)
354   // points to the end of the TCB + 0x7000. The pthread_descr structure is
355   // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
356   // TCB and the size of pthread_descr.
357   const uptr kTlsTcbOffset = 0x7000;
358   uptr thread_pointer;
359   asm volatile(".set push;\
360                 .set mips64r2;\
361                 rdhwr %0,$29;\
362                 .set pop" : "=r" (thread_pointer));
363   descr_addr = thread_pointer - kTlsTcbOffset - TlsPreTcbSize();
364 # elif defined(__aarch64__) || defined(__arm__)
365   descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer()) -
366                                       ThreadDescriptorSize();
367 # elif defined(__s390__)
368   descr_addr = reinterpret_cast<uptr>(__builtin_thread_pointer());
369 # elif defined(__powerpc64__)
370   // PPC64LE uses TLS variant I. The thread pointer (in GPR 13)
371   // points to the end of the TCB + 0x7000. The pthread_descr structure is
372   // immediately in front of the TCB. TlsPreTcbSize() includes the size of the
373   // TCB and the size of pthread_descr.
374   const uptr kTlsTcbOffset = 0x7000;
375   uptr thread_pointer;
376   asm("addi %0,13,%1" : "=r"(thread_pointer) : "I"(-kTlsTcbOffset));
377   descr_addr = thread_pointer - TlsPreTcbSize();
378 # else
379 #  error "unsupported CPU arch"
380 # endif
381   return descr_addr;
382 }
383 #endif  // (x86_64 || i386 || MIPS) && SANITIZER_LINUX
384 
385 #if SANITIZER_FREEBSD
386 static void **ThreadSelfSegbase() {
387   void **segbase = 0;
388 # if defined(__i386__)
389   // sysarch(I386_GET_GSBASE, segbase);
390   __asm __volatile("mov %%gs:0, %0" : "=r" (segbase));
391 # elif defined(__x86_64__)
392   // sysarch(AMD64_GET_FSBASE, segbase);
393   __asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
394 # else
395 #  error "unsupported CPU arch"
396 # endif
397   return segbase;
398 }
399 
400 uptr ThreadSelf() {
401   return (uptr)ThreadSelfSegbase()[2];
402 }
403 #endif  // SANITIZER_FREEBSD
404 
405 #if SANITIZER_NETBSD
406 static struct tls_tcb * ThreadSelfTlsTcb() {
407   return (struct tls_tcb *)_lwp_getprivate();
408 }
409 
410 uptr ThreadSelf() {
411   return (uptr)ThreadSelfTlsTcb()->tcb_pthread;
412 }
413 
414 int GetSizeFromHdr(struct dl_phdr_info *info, size_t size, void *data) {
415   const Elf_Phdr *hdr = info->dlpi_phdr;
416   const Elf_Phdr *last_hdr = hdr + info->dlpi_phnum;
417 
418   for (; hdr != last_hdr; ++hdr) {
419     if (hdr->p_type == PT_TLS && info->dlpi_tls_modid == 1) {
420       *(uptr*)data = hdr->p_memsz;
421       break;
422     }
423   }
424   return 0;
425 }
426 #endif  // SANITIZER_NETBSD
427 
428 #if !SANITIZER_GO
429 static void GetTls(uptr *addr, uptr *size) {
430 #if SANITIZER_LINUX && !SANITIZER_ANDROID
431 # if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
432   *addr = ThreadSelf();
433   *size = GetTlsSize();
434   *addr -= *size;
435   *addr += ThreadDescriptorSize();
436 # elif defined(__mips__) || defined(__aarch64__) || defined(__powerpc64__) \
437     || defined(__arm__)
438   *addr = ThreadSelf();
439   *size = GetTlsSize();
440 # else
441   *addr = 0;
442   *size = 0;
443 # endif
444 #elif SANITIZER_FREEBSD
445   void** segbase = ThreadSelfSegbase();
446   *addr = 0;
447   *size = 0;
448   if (segbase != 0) {
449     // tcbalign = 16
450     // tls_size = round(tls_static_space, tcbalign);
451     // dtv = segbase[1];
452     // dtv[2] = segbase - tls_static_space;
453     void **dtv = (void**) segbase[1];
454     *addr = (uptr) dtv[2];
455     *size = (*addr == 0) ? 0 : ((uptr) segbase[0] - (uptr) dtv[2]);
456   }
457 #elif SANITIZER_NETBSD
458   struct tls_tcb * const tcb = ThreadSelfTlsTcb();
459   *addr = 0;
460   *size = 0;
461   if (tcb != 0) {
462     // Find size (p_memsz) of dlpi_tls_modid 1 (TLS block of the main program).
463     // ld.elf_so hardcodes the index 1.
464     dl_iterate_phdr(GetSizeFromHdr, size);
465 
466     if (*size != 0) {
467       // The block has been found and tcb_dtv[1] contains the base address
468       *addr = (uptr)tcb->tcb_dtv[1];
469     }
470   }
471 #elif SANITIZER_OPENBSD
472   *addr = 0;
473   *size = 0;
474 #elif SANITIZER_ANDROID
475   *addr = 0;
476   *size = 0;
477 #elif SANITIZER_SOLARIS
478   // FIXME
479   *addr = 0;
480   *size = 0;
481 #else
482 # error "Unknown OS"
483 #endif
484 }
485 #endif
486 
487 #if !SANITIZER_GO
488 uptr GetTlsSize() {
489 #if SANITIZER_FREEBSD || SANITIZER_ANDROID || SANITIZER_NETBSD ||              \
490     SANITIZER_OPENBSD || SANITIZER_SOLARIS
491   uptr addr, size;
492   GetTls(&addr, &size);
493   return size;
494 #elif defined(__mips__) || defined(__powerpc64__)
495   return RoundUpTo(g_tls_size + TlsPreTcbSize(), 16);
496 #else
497   return g_tls_size;
498 #endif
499 }
500 #endif
501 
502 void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
503                           uptr *tls_addr, uptr *tls_size) {
504 #if SANITIZER_GO
505   // Stub implementation for Go.
506   *stk_addr = *stk_size = *tls_addr = *tls_size = 0;
507 #else
508   GetTls(tls_addr, tls_size);
509 
510   uptr stack_top, stack_bottom;
511   GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
512   *stk_addr = stack_bottom;
513   *stk_size = stack_top - stack_bottom;
514 
515   if (!main) {
516     // If stack and tls intersect, make them non-intersecting.
517     if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
518       CHECK_GT(*tls_addr + *tls_size, *stk_addr);
519       CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
520       *stk_size -= *tls_size;
521       *tls_addr = *stk_addr + *stk_size;
522     }
523   }
524 #endif
525 }
526 
527 #if !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
528 typedef ElfW(Phdr) Elf_Phdr;
529 #elif SANITIZER_WORDSIZE == 32 && __FreeBSD_version <= 902001 // v9.2
530 #define Elf_Phdr XElf32_Phdr
531 #define dl_phdr_info xdl_phdr_info
532 #define dl_iterate_phdr(c, b) xdl_iterate_phdr((c), (b))
533 #endif // !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
534 
535 struct DlIteratePhdrData {
536   InternalMmapVectorNoCtor<LoadedModule> *modules;
537   bool first;
538 };
539 
540 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
541   DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
542   InternalScopedString module_name(kMaxPathLength);
543   if (data->first) {
544     data->first = false;
545     // First module is the binary itself.
546     ReadBinaryNameCached(module_name.data(), module_name.size());
547   } else if (info->dlpi_name) {
548     module_name.append("%s", info->dlpi_name);
549   }
550   if (module_name[0] == '\0')
551     return 0;
552   LoadedModule cur_module;
553   cur_module.set(module_name.data(), info->dlpi_addr);
554   for (int i = 0; i < (int)info->dlpi_phnum; i++) {
555     const Elf_Phdr *phdr = &info->dlpi_phdr[i];
556     if (phdr->p_type == PT_LOAD) {
557       uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
558       uptr cur_end = cur_beg + phdr->p_memsz;
559       bool executable = phdr->p_flags & PF_X;
560       bool writable = phdr->p_flags & PF_W;
561       cur_module.addAddressRange(cur_beg, cur_end, executable,
562                                  writable);
563     }
564   }
565   data->modules->push_back(cur_module);
566   return 0;
567 }
568 
569 #if SANITIZER_ANDROID && __ANDROID_API__ < 21
570 extern "C" __attribute__((weak)) int dl_iterate_phdr(
571     int (*)(struct dl_phdr_info *, size_t, void *), void *);
572 #endif
573 
574 static bool requiresProcmaps() {
575 #if SANITIZER_ANDROID && __ANDROID_API__ <= 22
576   // Fall back to /proc/maps if dl_iterate_phdr is unavailable or broken.
577   // The runtime check allows the same library to work with
578   // both K and L (and future) Android releases.
579   return AndroidGetApiLevel() <= ANDROID_LOLLIPOP_MR1;
580 #else
581   return false;
582 #endif
583 }
584 
585 static void procmapsInit(InternalMmapVectorNoCtor<LoadedModule> *modules) {
586   MemoryMappingLayout memory_mapping(/*cache_enabled*/true);
587   memory_mapping.DumpListOfModules(modules);
588 }
589 
590 void ListOfModules::init() {
591   clearOrInit();
592   if (requiresProcmaps()) {
593     procmapsInit(&modules_);
594   } else {
595     DlIteratePhdrData data = {&modules_, true};
596     dl_iterate_phdr(dl_iterate_phdr_cb, &data);
597   }
598 }
599 
600 // When a custom loader is used, dl_iterate_phdr may not contain the full
601 // list of modules. Allow callers to fall back to using procmaps.
602 void ListOfModules::fallbackInit() {
603   if (!requiresProcmaps()) {
604     clearOrInit();
605     procmapsInit(&modules_);
606   } else {
607     clear();
608   }
609 }
610 
611 // getrusage does not give us the current RSS, only the max RSS.
612 // Still, this is better than nothing if /proc/self/statm is not available
613 // for some reason, e.g. due to a sandbox.
614 static uptr GetRSSFromGetrusage() {
615   struct rusage usage;
616   if (getrusage(RUSAGE_SELF, &usage))  // Failed, probably due to a sandbox.
617     return 0;
618   return usage.ru_maxrss << 10;  // ru_maxrss is in Kb.
619 }
620 
621 uptr GetRSS() {
622   if (!common_flags()->can_use_proc_maps_statm)
623     return GetRSSFromGetrusage();
624   fd_t fd = OpenFile("/proc/self/statm", RdOnly);
625   if (fd == kInvalidFd)
626     return GetRSSFromGetrusage();
627   char buf[64];
628   uptr len = internal_read(fd, buf, sizeof(buf) - 1);
629   internal_close(fd);
630   if ((sptr)len <= 0)
631     return 0;
632   buf[len] = 0;
633   // The format of the file is:
634   // 1084 89 69 11 0 79 0
635   // We need the second number which is RSS in pages.
636   char *pos = buf;
637   // Skip the first number.
638   while (*pos >= '0' && *pos <= '9')
639     pos++;
640   // Skip whitespaces.
641   while (!(*pos >= '0' && *pos <= '9') && *pos != 0)
642     pos++;
643   // Read the number.
644   uptr rss = 0;
645   while (*pos >= '0' && *pos <= '9')
646     rss = rss * 10 + *pos++ - '0';
647   return rss * GetPageSizeCached();
648 }
649 
650 // sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used on most platforms as
651 // they allocate memory.
652 u32 GetNumberOfCPUs() {
653 #if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD
654   u32 ncpu;
655   int req[2];
656   uptr len = sizeof(ncpu);
657   req[0] = CTL_HW;
658   req[1] = HW_NCPU;
659   CHECK_EQ(internal_sysctl(req, 2, &ncpu, &len, NULL, 0), 0);
660   return ncpu;
661 #elif SANITIZER_ANDROID && !defined(CPU_COUNT) && !defined(__aarch64__)
662   // Fall back to /sys/devices/system/cpu on Android when cpu_set_t doesn't
663   // exist in sched.h. That is the case for toolchains generated with older
664   // NDKs.
665   // This code doesn't work on AArch64 because internal_getdents makes use of
666   // the 64bit getdents syscall, but cpu_set_t seems to always exist on AArch64.
667   uptr fd = internal_open("/sys/devices/system/cpu", O_RDONLY | O_DIRECTORY);
668   if (internal_iserror(fd))
669     return 0;
670   InternalMmapVector<u8> buffer(4096);
671   uptr bytes_read = buffer.size();
672   uptr n_cpus = 0;
673   u8 *d_type;
674   struct linux_dirent *entry = (struct linux_dirent *)&buffer[bytes_read];
675   while (true) {
676     if ((u8 *)entry >= &buffer[bytes_read]) {
677       bytes_read = internal_getdents(fd, (struct linux_dirent *)buffer.data(),
678                                      buffer.size());
679       if (internal_iserror(bytes_read) || !bytes_read)
680         break;
681       entry = (struct linux_dirent *)buffer.data();
682     }
683     d_type = (u8 *)entry + entry->d_reclen - 1;
684     if (d_type >= &buffer[bytes_read] ||
685         (u8 *)&entry->d_name[3] >= &buffer[bytes_read])
686       break;
687     if (entry->d_ino != 0 && *d_type == DT_DIR) {
688       if (entry->d_name[0] == 'c' && entry->d_name[1] == 'p' &&
689           entry->d_name[2] == 'u' &&
690           entry->d_name[3] >= '0' && entry->d_name[3] <= '9')
691         n_cpus++;
692     }
693     entry = (struct linux_dirent *)(((u8 *)entry) + entry->d_reclen);
694   }
695   internal_close(fd);
696   return n_cpus;
697 #elif SANITIZER_SOLARIS
698   return sysconf(_SC_NPROCESSORS_ONLN);
699 #else
700   cpu_set_t CPUs;
701   CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
702   return CPU_COUNT(&CPUs);
703 #endif
704 }
705 
706 #if SANITIZER_LINUX
707 
708 # if SANITIZER_ANDROID
709 static atomic_uint8_t android_log_initialized;
710 
711 void AndroidLogInit() {
712   openlog(GetProcessName(), 0, LOG_USER);
713   atomic_store(&android_log_initialized, 1, memory_order_release);
714 }
715 
716 static bool ShouldLogAfterPrintf() {
717   return atomic_load(&android_log_initialized, memory_order_acquire);
718 }
719 
720 extern "C" SANITIZER_WEAK_ATTRIBUTE
721 int async_safe_write_log(int pri, const char* tag, const char* msg);
722 extern "C" SANITIZER_WEAK_ATTRIBUTE
723 int __android_log_write(int prio, const char* tag, const char* msg);
724 
725 // ANDROID_LOG_INFO is 4, but can't be resolved at runtime.
726 #define SANITIZER_ANDROID_LOG_INFO 4
727 
728 // async_safe_write_log is a new public version of __libc_write_log that is
729 // used behind syslog. It is preferable to syslog as it will not do any dynamic
730 // memory allocation or formatting.
731 // If the function is not available, syslog is preferred for L+ (it was broken
732 // pre-L) as __android_log_write triggers a racey behavior with the strncpy
733 // interceptor. Fallback to __android_log_write pre-L.
734 void WriteOneLineToSyslog(const char *s) {
735   if (&async_safe_write_log) {
736     async_safe_write_log(SANITIZER_ANDROID_LOG_INFO, GetProcessName(), s);
737   } else if (AndroidGetApiLevel() > ANDROID_KITKAT) {
738     syslog(LOG_INFO, "%s", s);
739   } else {
740     CHECK(&__android_log_write);
741     __android_log_write(SANITIZER_ANDROID_LOG_INFO, nullptr, s);
742   }
743 }
744 
745 extern "C" SANITIZER_WEAK_ATTRIBUTE
746 void android_set_abort_message(const char *);
747 
748 void SetAbortMessage(const char *str) {
749   if (&android_set_abort_message)
750     android_set_abort_message(str);
751 }
752 # else
753 void AndroidLogInit() {}
754 
755 static bool ShouldLogAfterPrintf() { return true; }
756 
757 void WriteOneLineToSyslog(const char *s) { syslog(LOG_INFO, "%s", s); }
758 
759 void SetAbortMessage(const char *str) {}
760 # endif  // SANITIZER_ANDROID
761 
762 void LogMessageOnPrintf(const char *str) {
763   if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
764     WriteToSyslog(str);
765 }
766 
767 #endif  // SANITIZER_LINUX
768 
769 #if SANITIZER_LINUX && !SANITIZER_GO
770 // glibc crashes when using clock_gettime from a preinit_array function as the
771 // vDSO function pointers haven't been initialized yet. __progname is
772 // initialized after the vDSO function pointers, so if it exists, is not null
773 // and is not empty, we can use clock_gettime.
774 extern "C" SANITIZER_WEAK_ATTRIBUTE char *__progname;
775 INLINE bool CanUseVDSO() {
776   // Bionic is safe, it checks for the vDSO function pointers to be initialized.
777   if (SANITIZER_ANDROID)
778     return true;
779   if (&__progname && __progname && *__progname)
780     return true;
781   return false;
782 }
783 
784 // MonotonicNanoTime is a timing function that can leverage the vDSO by calling
785 // clock_gettime. real_clock_gettime only exists if clock_gettime is
786 // intercepted, so define it weakly and use it if available.
787 extern "C" SANITIZER_WEAK_ATTRIBUTE
788 int real_clock_gettime(u32 clk_id, void *tp);
789 u64 MonotonicNanoTime() {
790   timespec ts;
791   if (CanUseVDSO()) {
792     if (&real_clock_gettime)
793       real_clock_gettime(CLOCK_MONOTONIC, &ts);
794     else
795       clock_gettime(CLOCK_MONOTONIC, &ts);
796   } else {
797     internal_clock_gettime(CLOCK_MONOTONIC, &ts);
798   }
799   return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
800 }
801 #else
802 // Non-Linux & Go always use the syscall.
803 u64 MonotonicNanoTime() {
804   timespec ts;
805   internal_clock_gettime(CLOCK_MONOTONIC, &ts);
806   return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
807 }
808 #endif  // SANITIZER_LINUX && !SANITIZER_GO
809 
810 #if !SANITIZER_OPENBSD
811 void ReExec() {
812   const char *pathname = "/proc/self/exe";
813 
814 #if SANITIZER_NETBSD
815   static const int name[] = {
816       CTL_KERN,
817       KERN_PROC_ARGS,
818       -1,
819       KERN_PROC_PATHNAME,
820   };
821   char path[400];
822   uptr len;
823 
824   len = sizeof(path);
825   if (internal_sysctl(name, ARRAY_SIZE(name), path, &len, NULL, 0) != -1)
826     pathname = path;
827 #elif SANITIZER_SOLARIS
828   pathname = getexecname();
829   CHECK_NE(pathname, NULL);
830 #elif SANITIZER_USE_GETAUXVAL
831   // Calling execve with /proc/self/exe sets that as $EXEC_ORIGIN. Binaries that
832   // rely on that will fail to load shared libraries. Query AT_EXECFN instead.
833   pathname = reinterpret_cast<const char *>(getauxval(AT_EXECFN));
834 #endif
835 
836   uptr rv = internal_execve(pathname, GetArgv(), GetEnviron());
837   int rverrno;
838   CHECK_EQ(internal_iserror(rv, &rverrno), true);
839   Printf("execve failed, errno %d\n", rverrno);
840   Die();
841 }
842 #endif  // !SANITIZER_OPENBSD
843 
844 } // namespace __sanitizer
845 
846 #endif
847