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_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 #if SANITIZER_NETBSD
32 #define _RTLD_SOURCE  // for __lwp_gettcb_fast() / __lwp_getprivate_fast()
33 #endif
34 
35 #include <dlfcn.h>  // for dlsym()
36 #include <link.h>
37 #include <pthread.h>
38 #include <signal.h>
39 #include <sys/mman.h>
40 #include <sys/resource.h>
41 #include <syslog.h>
42 
43 #if !defined(ElfW)
44 #define ElfW(type) Elf_##type
45 #endif
46 
47 #if SANITIZER_FREEBSD
48 #include <pthread_np.h>
49 #include <osreldate.h>
50 #include <sys/sysctl.h>
51 #define pthread_getattr_np pthread_attr_get_np
52 // The MAP_NORESERVE define has been removed in FreeBSD 11.x, and even before
53 // that, it was never implemented. So just define it to zero.
54 #undef MAP_NORESERVE
55 #define MAP_NORESERVE 0
56 #endif
57 
58 #if SANITIZER_NETBSD
59 #include <sys/sysctl.h>
60 #include <sys/tls.h>
61 #include <lwp.h>
62 #endif
63 
64 #if SANITIZER_SOLARIS
65 #include <stdlib.h>
66 #include <thread.h>
67 #endif
68 
69 #if SANITIZER_ANDROID
70 #include <android/api-level.h>
71 #if !defined(CPU_COUNT) && !defined(__aarch64__)
72 #include <dirent.h>
73 #include <fcntl.h>
74 struct __sanitizer::linux_dirent {
75   long           d_ino;
76   off_t          d_off;
77   unsigned short d_reclen;
78   char           d_name[];
79 };
80 #endif
81 #endif
82 
83 #if !SANITIZER_ANDROID
84 #include <elf.h>
85 #include <unistd.h>
86 #endif
87 
88 namespace __sanitizer {
89 
90 SANITIZER_WEAK_ATTRIBUTE int
91 real_sigaction(int signum, const void *act, void *oldact);
92 
93 int internal_sigaction(int signum, const void *act, void *oldact) {
94 #if !SANITIZER_GO
95   if (&real_sigaction)
96     return real_sigaction(signum, act, oldact);
97 #endif
98   return sigaction(signum, (const struct sigaction *)act,
99                    (struct sigaction *)oldact);
100 }
101 
102 void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
103                                 uptr *stack_bottom) {
104   CHECK(stack_top);
105   CHECK(stack_bottom);
106   if (at_initialization) {
107     // This is the main thread. Libpthread may not be initialized yet.
108     struct rlimit rl;
109     CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);
110 
111     // Find the mapping that contains a stack variable.
112     MemoryMappingLayout proc_maps(/*cache_enabled*/true);
113     if (proc_maps.Error()) {
114       *stack_top = *stack_bottom = 0;
115       return;
116     }
117     MemoryMappedSegment segment;
118     uptr prev_end = 0;
119     while (proc_maps.Next(&segment)) {
120       if ((uptr)&rl < segment.end) break;
121       prev_end = segment.end;
122     }
123     CHECK((uptr)&rl >= segment.start && (uptr)&rl < segment.end);
124 
125     // Get stacksize from rlimit, but clip it so that it does not overlap
126     // with other mappings.
127     uptr stacksize = rl.rlim_cur;
128     if (stacksize > segment.end - prev_end) stacksize = segment.end - prev_end;
129     // When running with unlimited stack size, we still want to set some limit.
130     // The unlimited stack size is caused by 'ulimit -s unlimited'.
131     // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
132     if (stacksize > kMaxThreadStackSize)
133       stacksize = kMaxThreadStackSize;
134     *stack_top = segment.end;
135     *stack_bottom = segment.end - stacksize;
136     return;
137   }
138   uptr stacksize = 0;
139   void *stackaddr = nullptr;
140 #if SANITIZER_SOLARIS
141   stack_t ss;
142   CHECK_EQ(thr_stksegment(&ss), 0);
143   stacksize = ss.ss_size;
144   stackaddr = (char *)ss.ss_sp - stacksize;
145 #else  // !SANITIZER_SOLARIS
146   pthread_attr_t attr;
147   pthread_attr_init(&attr);
148   CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
149   my_pthread_attr_getstack(&attr, &stackaddr, &stacksize);
150   pthread_attr_destroy(&attr);
151 #endif  // SANITIZER_SOLARIS
152 
153   *stack_top = (uptr)stackaddr + stacksize;
154   *stack_bottom = (uptr)stackaddr;
155 }
156 
157 #if !SANITIZER_GO
158 bool SetEnv(const char *name, const char *value) {
159   void *f = dlsym(RTLD_NEXT, "setenv");
160   if (!f)
161     return false;
162   typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
163   setenv_ft setenv_f;
164   CHECK_EQ(sizeof(setenv_f), sizeof(f));
165   internal_memcpy(&setenv_f, &f, sizeof(f));
166   return setenv_f(name, value, 1) == 0;
167 }
168 #endif
169 
170 __attribute__((unused)) static bool GetLibcVersion(int *major, int *minor,
171                                                    int *patch) {
172 #ifdef _CS_GNU_LIBC_VERSION
173   char buf[64];
174   uptr len = confstr(_CS_GNU_LIBC_VERSION, buf, sizeof(buf));
175   if (len >= sizeof(buf))
176     return false;
177   buf[len] = 0;
178   static const char kGLibC[] = "glibc ";
179   if (internal_strncmp(buf, kGLibC, sizeof(kGLibC) - 1) != 0)
180     return false;
181   const char *p = buf + sizeof(kGLibC) - 1;
182   *major = internal_simple_strtoll(p, &p, 10);
183   *minor = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
184   *patch = (*p == '.') ? internal_simple_strtoll(p + 1, &p, 10) : 0;
185   return true;
186 #else
187   return false;
188 #endif
189 }
190 
191 // True if we can use dlpi_tls_data. glibc before 2.25 may leave NULL (BZ
192 // #19826) so dlpi_tls_data cannot be used.
193 //
194 // musl before 1.2.3 and FreeBSD as of 12.2 incorrectly set dlpi_tls_data to
195 // the TLS initialization image
196 // https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=254774
197 __attribute__((unused)) static int g_use_dlpi_tls_data;
198 
199 #if SANITIZER_GLIBC && !SANITIZER_GO
200 __attribute__((unused)) static uptr g_tls_size;
201 void InitTlsSize() {
202   int major, minor, patch;
203   g_use_dlpi_tls_data =
204       GetLibcVersion(&major, &minor, &patch) && major == 2 && minor >= 25;
205 
206 #if defined(__x86_64__) || defined(__powerpc64__)
207   void *get_tls_static_info = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
208   size_t tls_align;
209   ((void (*)(size_t *, size_t *))get_tls_static_info)(&g_tls_size, &tls_align);
210 #endif
211 }
212 #else
213 void InitTlsSize() { }
214 #endif  // SANITIZER_GLIBC && !SANITIZER_GO
215 
216 // On glibc x86_64, ThreadDescriptorSize() needs to be precise due to the usage
217 // of g_tls_size. On other targets, ThreadDescriptorSize() is only used by lsan
218 // to get the pointer to thread-specific data keys in the thread control block.
219 #if (defined(__x86_64__) || defined(__i386__) || defined(__mips__) ||       \
220      defined(__aarch64__) || defined(__powerpc64__) || defined(__s390__) || \
221      defined(__arm__) || SANITIZER_RISCV64) &&                              \
222     (SANITIZER_FREEBSD || SANITIZER_LINUX) && !SANITIZER_ANDROID
223 // sizeof(struct pthread) from glibc.
224 static atomic_uintptr_t thread_descriptor_size;
225 
226 uptr ThreadDescriptorSize() {
227   uptr val = atomic_load_relaxed(&thread_descriptor_size);
228   if (val)
229     return val;
230 #if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
231   int major;
232   int minor;
233   int patch;
234   if (GetLibcVersion(&major, &minor, &patch) && major == 2) {
235     /* sizeof(struct pthread) values from various glibc versions.  */
236     if (SANITIZER_X32)
237       val = 1728; // Assume only one particular version for x32.
238     // For ARM sizeof(struct pthread) changed in Glibc 2.23.
239     else if (SANITIZER_ARM)
240       val = minor <= 22 ? 1120 : 1216;
241     else if (minor <= 3)
242       val = FIRST_32_SECOND_64(1104, 1696);
243     else if (minor == 4)
244       val = FIRST_32_SECOND_64(1120, 1728);
245     else if (minor == 5)
246       val = FIRST_32_SECOND_64(1136, 1728);
247     else if (minor <= 9)
248       val = FIRST_32_SECOND_64(1136, 1712);
249     else if (minor == 10)
250       val = FIRST_32_SECOND_64(1168, 1776);
251     else if (minor == 11 || (minor == 12 && patch == 1))
252       val = FIRST_32_SECOND_64(1168, 2288);
253     else if (minor <= 14)
254       val = FIRST_32_SECOND_64(1168, 2304);
255     else if (minor < 32)  // Unknown version
256       val = FIRST_32_SECOND_64(1216, 2304);
257     else  // minor == 32
258       val = FIRST_32_SECOND_64(1344, 2496);
259   }
260 #elif defined(__mips__)
261   // TODO(sagarthakur): add more values as per different glibc versions.
262   val = FIRST_32_SECOND_64(1152, 1776);
263 #elif SANITIZER_RISCV64
264   int major;
265   int minor;
266   int patch;
267   if (GetLibcVersion(&major, &minor, &patch) && major == 2) {
268     // TODO: consider adding an optional runtime check for an unknown (untested)
269     // glibc version
270     if (minor <= 28)  // WARNING: the highest tested version is 2.29
271       val = 1772;     // no guarantees for this one
272     else if (minor <= 31)
273       val = 1772;  // tested against glibc 2.29, 2.31
274     else
275       val = 1936;  // tested against glibc 2.32
276   }
277 
278 #elif defined(__aarch64__)
279   // The sizeof (struct pthread) is the same from GLIBC 2.17 to 2.22.
280   val = 1776;
281 #elif defined(__powerpc64__)
282   val = 1776; // from glibc.ppc64le 2.20-8.fc21
283 #elif defined(__s390__)
284   val = FIRST_32_SECOND_64(1152, 1776); // valid for glibc 2.22
285 #endif
286   if (val)
287     atomic_store_relaxed(&thread_descriptor_size, val);
288   return val;
289 }
290 
291 #if defined(__mips__) || defined(__powerpc64__) || SANITIZER_RISCV64
292 // TlsPreTcbSize includes size of struct pthread_descr and size of tcb
293 // head structure. It lies before the static tls blocks.
294 static uptr TlsPreTcbSize() {
295 #if defined(__mips__)
296   const uptr kTcbHead = 16; // sizeof (tcbhead_t)
297 #elif defined(__powerpc64__)
298   const uptr kTcbHead = 88; // sizeof (tcbhead_t)
299 #elif SANITIZER_RISCV64
300   const uptr kTcbHead = 16;  // sizeof (tcbhead_t)
301 #endif
302   const uptr kTlsAlign = 16;
303   const uptr kTlsPreTcbSize =
304       RoundUpTo(ThreadDescriptorSize() + kTcbHead, kTlsAlign);
305   return kTlsPreTcbSize;
306 }
307 #endif
308 
309 #if !SANITIZER_GO
310 namespace {
311 struct TlsBlock {
312   uptr begin, end, align;
313   size_t tls_modid;
314   bool operator<(const TlsBlock &rhs) const { return begin < rhs.begin; }
315 };
316 }  // namespace
317 
318 extern "C" void *__tls_get_addr(size_t *);
319 
320 static int CollectStaticTlsBlocks(struct dl_phdr_info *info, size_t size,
321                                   void *data) {
322   if (!info->dlpi_tls_modid)
323     return 0;
324   uptr begin = (uptr)info->dlpi_tls_data;
325 #ifndef __s390__
326   if (!g_use_dlpi_tls_data) {
327     // Call __tls_get_addr as a fallback. This forces TLS allocation on glibc
328     // and FreeBSD.
329     size_t mod_and_off[2] = {info->dlpi_tls_modid, 0};
330     begin = (uptr)__tls_get_addr(mod_and_off);
331   }
332 #endif
333   for (unsigned i = 0; i != info->dlpi_phnum; ++i)
334     if (info->dlpi_phdr[i].p_type == PT_TLS) {
335       static_cast<InternalMmapVector<TlsBlock> *>(data)->push_back(
336           TlsBlock{begin, begin + info->dlpi_phdr[i].p_memsz,
337                    info->dlpi_phdr[i].p_align, info->dlpi_tls_modid});
338       break;
339     }
340   return 0;
341 }
342 
343 __attribute__((unused)) static void GetStaticTlsBoundary(uptr *addr, uptr *size,
344                                                          uptr *align) {
345   InternalMmapVector<TlsBlock> ranges;
346   dl_iterate_phdr(CollectStaticTlsBlocks, &ranges);
347   uptr len = ranges.size();
348   Sort(ranges.begin(), len);
349   // Find the range with tls_modid=1. For glibc, because libc.so uses PT_TLS,
350   // this module is guaranteed to exist and is one of the initially loaded
351   // modules.
352   uptr one = 0;
353   while (one != len && ranges[one].tls_modid != 1) ++one;
354   if (one == len) {
355     // This may happen with musl if no module uses PT_TLS.
356     *addr = 0;
357     *size = 0;
358     *align = 1;
359     return;
360   }
361   // Find the maximum consecutive ranges. We consider two modules consecutive if
362   // the gap is smaller than the alignment. The dynamic loader places static TLS
363   // blocks this way not to waste space.
364   uptr l = one;
365   *align = ranges[l].align;
366   while (l != 0 && ranges[l].begin < ranges[l - 1].end + ranges[l - 1].align)
367     *align = Max(*align, ranges[--l].align);
368   uptr r = one + 1;
369   while (r != len && ranges[r].begin < ranges[r - 1].end + ranges[r - 1].align)
370     *align = Max(*align, ranges[r++].align);
371   *addr = ranges[l].begin;
372   *size = ranges[r - 1].end - ranges[l].begin;
373 }
374 #endif  // !SANITIZER_GO
375 #endif  // (x86_64 || i386 || mips || ...) && (SANITIZER_FREEBSD ||
376         // SANITIZER_LINUX) && !SANITIZER_ANDROID
377 
378 #if SANITIZER_NETBSD
379 static struct tls_tcb * ThreadSelfTlsTcb() {
380   struct tls_tcb *tcb = nullptr;
381 #ifdef __HAVE___LWP_GETTCB_FAST
382   tcb = (struct tls_tcb *)__lwp_gettcb_fast();
383 #elif defined(__HAVE___LWP_GETPRIVATE_FAST)
384   tcb = (struct tls_tcb *)__lwp_getprivate_fast();
385 #endif
386   return tcb;
387 }
388 
389 uptr ThreadSelf() {
390   return (uptr)ThreadSelfTlsTcb()->tcb_pthread;
391 }
392 
393 int GetSizeFromHdr(struct dl_phdr_info *info, size_t size, void *data) {
394   const Elf_Phdr *hdr = info->dlpi_phdr;
395   const Elf_Phdr *last_hdr = hdr + info->dlpi_phnum;
396 
397   for (; hdr != last_hdr; ++hdr) {
398     if (hdr->p_type == PT_TLS && info->dlpi_tls_modid == 1) {
399       *(uptr*)data = hdr->p_memsz;
400       break;
401     }
402   }
403   return 0;
404 }
405 #endif  // SANITIZER_NETBSD
406 
407 #if SANITIZER_ANDROID
408 // Bionic provides this API since S.
409 extern "C" SANITIZER_WEAK_ATTRIBUTE void __libc_get_static_tls_bounds(void **,
410                                                                       void **);
411 #endif
412 
413 #if !SANITIZER_GO
414 static void GetTls(uptr *addr, uptr *size) {
415 #if SANITIZER_ANDROID
416   if (&__libc_get_static_tls_bounds) {
417     void *start_addr;
418     void *end_addr;
419     __libc_get_static_tls_bounds(&start_addr, &end_addr);
420     *addr = reinterpret_cast<uptr>(start_addr);
421     *size =
422         reinterpret_cast<uptr>(end_addr) - reinterpret_cast<uptr>(start_addr);
423   } else {
424     *addr = 0;
425     *size = 0;
426   }
427 #elif SANITIZER_GLIBC && defined(__x86_64__)
428   // For x86-64, use an O(1) approach which requires precise
429   // ThreadDescriptorSize. g_tls_size was initialized in InitTlsSize.
430   asm("mov %%fs:16,%0" : "=r"(*addr));
431   *size = g_tls_size;
432   *addr -= *size;
433   *addr += ThreadDescriptorSize();
434 #elif SANITIZER_GLIBC && defined(__powerpc64__)
435   // Workaround for glibc<2.25(?). 2.27 is known to not need this.
436   uptr tp;
437   asm("addi %0,13,-0x7000" : "=r"(tp));
438   const uptr pre_tcb_size = TlsPreTcbSize();
439   *addr = tp - pre_tcb_size;
440   *size = g_tls_size + pre_tcb_size;
441 #elif SANITIZER_FREEBSD || SANITIZER_LINUX
442   uptr align;
443   GetStaticTlsBoundary(addr, size, &align);
444 #if defined(__x86_64__) || defined(__i386__) || defined(__s390__)
445   if (SANITIZER_GLIBC) {
446 #if defined(__s390__)
447     align = Max<uptr>(align, 16);
448 #else
449     align = Max<uptr>(align, 64);
450 #endif
451   }
452   const uptr tp = RoundUpTo(*addr + *size, align);
453 
454   // lsan requires the range to additionally cover the static TLS surplus
455   // (elf/dl-tls.c defines 1664). Otherwise there may be false positives for
456   // allocations only referenced by tls in dynamically loaded modules.
457   if (SANITIZER_GLIBC)
458     *size += 1644;
459   else if (SANITIZER_FREEBSD)
460     *size += 128;  // RTLD_STATIC_TLS_EXTRA
461 
462   // Extend the range to include the thread control block. On glibc, lsan needs
463   // the range to include pthread::{specific_1stblock,specific} so that
464   // allocations only referenced by pthread_setspecific can be scanned. This may
465   // underestimate by at most TLS_TCB_ALIGN-1 bytes but it should be fine
466   // because the number of bytes after pthread::specific is larger.
467   *addr = tp - RoundUpTo(*size, align);
468   *size = tp - *addr + ThreadDescriptorSize();
469 #else
470   if (SANITIZER_GLIBC)
471     *size += 1664;
472   else if (SANITIZER_FREEBSD)
473     *size += 128;  // RTLD_STATIC_TLS_EXTRA
474 #if defined(__mips__) || defined(__powerpc64__) || SANITIZER_RISCV64
475   const uptr pre_tcb_size = TlsPreTcbSize();
476   *addr -= pre_tcb_size;
477   *size += pre_tcb_size;
478 #else
479   // arm and aarch64 reserve two words at TP, so this underestimates the range.
480   // However, this is sufficient for the purpose of finding the pointers to
481   // thread-specific data keys.
482   const uptr tcb_size = ThreadDescriptorSize();
483   *addr -= tcb_size;
484   *size += tcb_size;
485 #endif
486 #endif
487 #elif SANITIZER_NETBSD
488   struct tls_tcb * const tcb = ThreadSelfTlsTcb();
489   *addr = 0;
490   *size = 0;
491   if (tcb != 0) {
492     // Find size (p_memsz) of dlpi_tls_modid 1 (TLS block of the main program).
493     // ld.elf_so hardcodes the index 1.
494     dl_iterate_phdr(GetSizeFromHdr, size);
495 
496     if (*size != 0) {
497       // The block has been found and tcb_dtv[1] contains the base address
498       *addr = (uptr)tcb->tcb_dtv[1];
499     }
500   }
501 #elif SANITIZER_SOLARIS
502   // FIXME
503   *addr = 0;
504   *size = 0;
505 #else
506 #error "Unknown OS"
507 #endif
508 }
509 #endif
510 
511 #if !SANITIZER_GO
512 uptr GetTlsSize() {
513 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
514     SANITIZER_SOLARIS
515   uptr addr, size;
516   GetTls(&addr, &size);
517   return size;
518 #else
519   return 0;
520 #endif
521 }
522 #endif
523 
524 void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
525                           uptr *tls_addr, uptr *tls_size) {
526 #if SANITIZER_GO
527   // Stub implementation for Go.
528   *stk_addr = *stk_size = *tls_addr = *tls_size = 0;
529 #else
530   GetTls(tls_addr, tls_size);
531 
532   uptr stack_top, stack_bottom;
533   GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
534   *stk_addr = stack_bottom;
535   *stk_size = stack_top - stack_bottom;
536 
537   if (!main) {
538     // If stack and tls intersect, make them non-intersecting.
539     if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
540       if (*stk_addr + *stk_size < *tls_addr + *tls_size)
541         *tls_size = *stk_addr + *stk_size - *tls_addr;
542       *stk_size = *tls_addr - *stk_addr;
543     }
544   }
545 #endif
546 }
547 
548 #if !SANITIZER_FREEBSD
549 typedef ElfW(Phdr) Elf_Phdr;
550 #elif SANITIZER_WORDSIZE == 32 && __FreeBSD_version <= 902001  // v9.2
551 #define Elf_Phdr XElf32_Phdr
552 #define dl_phdr_info xdl_phdr_info
553 #define dl_iterate_phdr(c, b) xdl_iterate_phdr((c), (b))
554 #endif  // !SANITIZER_FREEBSD
555 
556 struct DlIteratePhdrData {
557   InternalMmapVectorNoCtor<LoadedModule> *modules;
558   bool first;
559 };
560 
561 static int AddModuleSegments(const char *module_name, dl_phdr_info *info,
562                              InternalMmapVectorNoCtor<LoadedModule> *modules) {
563   if (module_name[0] == '\0')
564     return 0;
565   LoadedModule cur_module;
566   cur_module.set(module_name, info->dlpi_addr);
567   for (int i = 0; i < (int)info->dlpi_phnum; i++) {
568     const Elf_Phdr *phdr = &info->dlpi_phdr[i];
569     if (phdr->p_type == PT_LOAD) {
570       uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
571       uptr cur_end = cur_beg + phdr->p_memsz;
572       bool executable = phdr->p_flags & PF_X;
573       bool writable = phdr->p_flags & PF_W;
574       cur_module.addAddressRange(cur_beg, cur_end, executable,
575                                  writable);
576     }
577   }
578   modules->push_back(cur_module);
579   return 0;
580 }
581 
582 static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
583   DlIteratePhdrData *data = (DlIteratePhdrData *)arg;
584   if (data->first) {
585     InternalMmapVector<char> module_name(kMaxPathLength);
586     data->first = false;
587     // First module is the binary itself.
588     ReadBinaryNameCached(module_name.data(), module_name.size());
589     return AddModuleSegments(module_name.data(), info, data->modules);
590   }
591 
592   if (info->dlpi_name) {
593     InternalScopedString module_name;
594     module_name.append("%s", info->dlpi_name);
595     return AddModuleSegments(module_name.data(), info, data->modules);
596   }
597 
598   return 0;
599 }
600 
601 #if SANITIZER_ANDROID && __ANDROID_API__ < 21
602 extern "C" __attribute__((weak)) int dl_iterate_phdr(
603     int (*)(struct dl_phdr_info *, size_t, void *), void *);
604 #endif
605 
606 static bool requiresProcmaps() {
607 #if SANITIZER_ANDROID && __ANDROID_API__ <= 22
608   // Fall back to /proc/maps if dl_iterate_phdr is unavailable or broken.
609   // The runtime check allows the same library to work with
610   // both K and L (and future) Android releases.
611   return AndroidGetApiLevel() <= ANDROID_LOLLIPOP_MR1;
612 #else
613   return false;
614 #endif
615 }
616 
617 static void procmapsInit(InternalMmapVectorNoCtor<LoadedModule> *modules) {
618   MemoryMappingLayout memory_mapping(/*cache_enabled*/true);
619   memory_mapping.DumpListOfModules(modules);
620 }
621 
622 void ListOfModules::init() {
623   clearOrInit();
624   if (requiresProcmaps()) {
625     procmapsInit(&modules_);
626   } else {
627     DlIteratePhdrData data = {&modules_, true};
628     dl_iterate_phdr(dl_iterate_phdr_cb, &data);
629   }
630 }
631 
632 // When a custom loader is used, dl_iterate_phdr may not contain the full
633 // list of modules. Allow callers to fall back to using procmaps.
634 void ListOfModules::fallbackInit() {
635   if (!requiresProcmaps()) {
636     clearOrInit();
637     procmapsInit(&modules_);
638   } else {
639     clear();
640   }
641 }
642 
643 // getrusage does not give us the current RSS, only the max RSS.
644 // Still, this is better than nothing if /proc/self/statm is not available
645 // for some reason, e.g. due to a sandbox.
646 static uptr GetRSSFromGetrusage() {
647   struct rusage usage;
648   if (getrusage(RUSAGE_SELF, &usage))  // Failed, probably due to a sandbox.
649     return 0;
650   return usage.ru_maxrss << 10;  // ru_maxrss is in Kb.
651 }
652 
653 uptr GetRSS() {
654   if (!common_flags()->can_use_proc_maps_statm)
655     return GetRSSFromGetrusage();
656   fd_t fd = OpenFile("/proc/self/statm", RdOnly);
657   if (fd == kInvalidFd)
658     return GetRSSFromGetrusage();
659   char buf[64];
660   uptr len = internal_read(fd, buf, sizeof(buf) - 1);
661   internal_close(fd);
662   if ((sptr)len <= 0)
663     return 0;
664   buf[len] = 0;
665   // The format of the file is:
666   // 1084 89 69 11 0 79 0
667   // We need the second number which is RSS in pages.
668   char *pos = buf;
669   // Skip the first number.
670   while (*pos >= '0' && *pos <= '9')
671     pos++;
672   // Skip whitespaces.
673   while (!(*pos >= '0' && *pos <= '9') && *pos != 0)
674     pos++;
675   // Read the number.
676   uptr rss = 0;
677   while (*pos >= '0' && *pos <= '9')
678     rss = rss * 10 + *pos++ - '0';
679   return rss * GetPageSizeCached();
680 }
681 
682 // sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used on most platforms as
683 // they allocate memory.
684 u32 GetNumberOfCPUs() {
685 #if SANITIZER_FREEBSD || SANITIZER_NETBSD
686   u32 ncpu;
687   int req[2];
688   uptr len = sizeof(ncpu);
689   req[0] = CTL_HW;
690   req[1] = HW_NCPU;
691   CHECK_EQ(internal_sysctl(req, 2, &ncpu, &len, NULL, 0), 0);
692   return ncpu;
693 #elif SANITIZER_ANDROID && !defined(CPU_COUNT) && !defined(__aarch64__)
694   // Fall back to /sys/devices/system/cpu on Android when cpu_set_t doesn't
695   // exist in sched.h. That is the case for toolchains generated with older
696   // NDKs.
697   // This code doesn't work on AArch64 because internal_getdents makes use of
698   // the 64bit getdents syscall, but cpu_set_t seems to always exist on AArch64.
699   uptr fd = internal_open("/sys/devices/system/cpu", O_RDONLY | O_DIRECTORY);
700   if (internal_iserror(fd))
701     return 0;
702   InternalMmapVector<u8> buffer(4096);
703   uptr bytes_read = buffer.size();
704   uptr n_cpus = 0;
705   u8 *d_type;
706   struct linux_dirent *entry = (struct linux_dirent *)&buffer[bytes_read];
707   while (true) {
708     if ((u8 *)entry >= &buffer[bytes_read]) {
709       bytes_read = internal_getdents(fd, (struct linux_dirent *)buffer.data(),
710                                      buffer.size());
711       if (internal_iserror(bytes_read) || !bytes_read)
712         break;
713       entry = (struct linux_dirent *)buffer.data();
714     }
715     d_type = (u8 *)entry + entry->d_reclen - 1;
716     if (d_type >= &buffer[bytes_read] ||
717         (u8 *)&entry->d_name[3] >= &buffer[bytes_read])
718       break;
719     if (entry->d_ino != 0 && *d_type == DT_DIR) {
720       if (entry->d_name[0] == 'c' && entry->d_name[1] == 'p' &&
721           entry->d_name[2] == 'u' &&
722           entry->d_name[3] >= '0' && entry->d_name[3] <= '9')
723         n_cpus++;
724     }
725     entry = (struct linux_dirent *)(((u8 *)entry) + entry->d_reclen);
726   }
727   internal_close(fd);
728   return n_cpus;
729 #elif SANITIZER_SOLARIS
730   return sysconf(_SC_NPROCESSORS_ONLN);
731 #else
732   cpu_set_t CPUs;
733   CHECK_EQ(sched_getaffinity(0, sizeof(cpu_set_t), &CPUs), 0);
734   return CPU_COUNT(&CPUs);
735 #endif
736 }
737 
738 #if SANITIZER_LINUX
739 
740 #if SANITIZER_ANDROID
741 static atomic_uint8_t android_log_initialized;
742 
743 void AndroidLogInit() {
744   openlog(GetProcessName(), 0, LOG_USER);
745   atomic_store(&android_log_initialized, 1, memory_order_release);
746 }
747 
748 static bool ShouldLogAfterPrintf() {
749   return atomic_load(&android_log_initialized, memory_order_acquire);
750 }
751 
752 extern "C" SANITIZER_WEAK_ATTRIBUTE
753 int async_safe_write_log(int pri, const char* tag, const char* msg);
754 extern "C" SANITIZER_WEAK_ATTRIBUTE
755 int __android_log_write(int prio, const char* tag, const char* msg);
756 
757 // ANDROID_LOG_INFO is 4, but can't be resolved at runtime.
758 #define SANITIZER_ANDROID_LOG_INFO 4
759 
760 // async_safe_write_log is a new public version of __libc_write_log that is
761 // used behind syslog. It is preferable to syslog as it will not do any dynamic
762 // memory allocation or formatting.
763 // If the function is not available, syslog is preferred for L+ (it was broken
764 // pre-L) as __android_log_write triggers a racey behavior with the strncpy
765 // interceptor. Fallback to __android_log_write pre-L.
766 void WriteOneLineToSyslog(const char *s) {
767   if (&async_safe_write_log) {
768     async_safe_write_log(SANITIZER_ANDROID_LOG_INFO, GetProcessName(), s);
769   } else if (AndroidGetApiLevel() > ANDROID_KITKAT) {
770     syslog(LOG_INFO, "%s", s);
771   } else {
772     CHECK(&__android_log_write);
773     __android_log_write(SANITIZER_ANDROID_LOG_INFO, nullptr, s);
774   }
775 }
776 
777 extern "C" SANITIZER_WEAK_ATTRIBUTE
778 void android_set_abort_message(const char *);
779 
780 void SetAbortMessage(const char *str) {
781   if (&android_set_abort_message)
782     android_set_abort_message(str);
783 }
784 #else
785 void AndroidLogInit() {}
786 
787 static bool ShouldLogAfterPrintf() { return true; }
788 
789 void WriteOneLineToSyslog(const char *s) { syslog(LOG_INFO, "%s", s); }
790 
791 void SetAbortMessage(const char *str) {}
792 #endif  // SANITIZER_ANDROID
793 
794 void LogMessageOnPrintf(const char *str) {
795   if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
796     WriteToSyslog(str);
797 }
798 
799 #endif  // SANITIZER_LINUX
800 
801 #if SANITIZER_GLIBC && !SANITIZER_GO
802 // glibc crashes when using clock_gettime from a preinit_array function as the
803 // vDSO function pointers haven't been initialized yet. __progname is
804 // initialized after the vDSO function pointers, so if it exists, is not null
805 // and is not empty, we can use clock_gettime.
806 extern "C" SANITIZER_WEAK_ATTRIBUTE char *__progname;
807 inline bool CanUseVDSO() { return &__progname && __progname && *__progname; }
808 
809 // MonotonicNanoTime is a timing function that can leverage the vDSO by calling
810 // clock_gettime. real_clock_gettime only exists if clock_gettime is
811 // intercepted, so define it weakly and use it if available.
812 extern "C" SANITIZER_WEAK_ATTRIBUTE
813 int real_clock_gettime(u32 clk_id, void *tp);
814 u64 MonotonicNanoTime() {
815   timespec ts;
816   if (CanUseVDSO()) {
817     if (&real_clock_gettime)
818       real_clock_gettime(CLOCK_MONOTONIC, &ts);
819     else
820       clock_gettime(CLOCK_MONOTONIC, &ts);
821   } else {
822     internal_clock_gettime(CLOCK_MONOTONIC, &ts);
823   }
824   return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
825 }
826 #else
827 // Non-glibc & Go always use the regular function.
828 u64 MonotonicNanoTime() {
829   timespec ts;
830   clock_gettime(CLOCK_MONOTONIC, &ts);
831   return (u64)ts.tv_sec * (1000ULL * 1000 * 1000) + ts.tv_nsec;
832 }
833 #endif  // SANITIZER_GLIBC && !SANITIZER_GO
834 
835 void ReExec() {
836   const char *pathname = "/proc/self/exe";
837 
838 #if SANITIZER_NETBSD
839   static const int name[] = {
840       CTL_KERN,
841       KERN_PROC_ARGS,
842       -1,
843       KERN_PROC_PATHNAME,
844   };
845   char path[400];
846   uptr len;
847 
848   len = sizeof(path);
849   if (internal_sysctl(name, ARRAY_SIZE(name), path, &len, NULL, 0) != -1)
850     pathname = path;
851 #elif SANITIZER_SOLARIS
852   pathname = getexecname();
853   CHECK_NE(pathname, NULL);
854 #elif SANITIZER_USE_GETAUXVAL
855   // Calling execve with /proc/self/exe sets that as $EXEC_ORIGIN. Binaries that
856   // rely on that will fail to load shared libraries. Query AT_EXECFN instead.
857   pathname = reinterpret_cast<const char *>(getauxval(AT_EXECFN));
858 #endif
859 
860   uptr rv = internal_execve(pathname, GetArgv(), GetEnviron());
861   int rverrno;
862   CHECK_EQ(internal_iserror(rv, &rverrno), true);
863   Printf("execve failed, errno %d\n", rverrno);
864   Die();
865 }
866 
867 void UnmapFromTo(uptr from, uptr to) {
868   if (to == from)
869     return;
870   CHECK(to >= from);
871   uptr res = internal_munmap(reinterpret_cast<void *>(from), to - from);
872   if (UNLIKELY(internal_iserror(res))) {
873     Report("ERROR: %s failed to unmap 0x%zx (%zd) bytes at address %p\n",
874            SanitizerToolName, to - from, to - from, (void *)from);
875     CHECK("unable to unmap" && 0);
876   }
877 }
878 
879 uptr MapDynamicShadow(uptr shadow_size_bytes, uptr shadow_scale,
880                       uptr min_shadow_base_alignment,
881                       UNUSED uptr &high_mem_end) {
882   const uptr granularity = GetMmapGranularity();
883   const uptr alignment =
884       Max<uptr>(granularity << shadow_scale, 1ULL << min_shadow_base_alignment);
885   const uptr left_padding =
886       Max<uptr>(granularity, 1ULL << min_shadow_base_alignment);
887 
888   const uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity);
889   const uptr map_size = shadow_size + left_padding + alignment;
890 
891   const uptr map_start = (uptr)MmapNoAccess(map_size);
892   CHECK_NE(map_start, ~(uptr)0);
893 
894   const uptr shadow_start = RoundUpTo(map_start + left_padding, alignment);
895 
896   UnmapFromTo(map_start, shadow_start - left_padding);
897   UnmapFromTo(shadow_start + shadow_size, map_start + map_size);
898 
899   return shadow_start;
900 }
901 
902 static uptr MmapSharedNoReserve(uptr addr, uptr size) {
903   return internal_mmap(
904       reinterpret_cast<void *>(addr), size, PROT_READ | PROT_WRITE,
905       MAP_FIXED | MAP_SHARED | MAP_ANONYMOUS | MAP_NORESERVE, -1, 0);
906 }
907 
908 static uptr MremapCreateAlias(uptr base_addr, uptr alias_addr,
909                               uptr alias_size) {
910 #if SANITIZER_LINUX
911   return internal_mremap(reinterpret_cast<void *>(base_addr), 0, alias_size,
912                          MREMAP_MAYMOVE | MREMAP_FIXED,
913                          reinterpret_cast<void *>(alias_addr));
914 #else
915   CHECK(false && "mremap is not supported outside of Linux");
916   return 0;
917 #endif
918 }
919 
920 static void CreateAliases(uptr start_addr, uptr alias_size, uptr num_aliases) {
921   uptr total_size = alias_size * num_aliases;
922   uptr mapped = MmapSharedNoReserve(start_addr, total_size);
923   CHECK_EQ(mapped, start_addr);
924 
925   for (uptr i = 1; i < num_aliases; ++i) {
926     uptr alias_addr = start_addr + i * alias_size;
927     CHECK_EQ(MremapCreateAlias(start_addr, alias_addr, alias_size), alias_addr);
928   }
929 }
930 
931 uptr MapDynamicShadowAndAliases(uptr shadow_size, uptr alias_size,
932                                 uptr num_aliases, uptr ring_buffer_size) {
933   CHECK_EQ(alias_size & (alias_size - 1), 0);
934   CHECK_EQ(num_aliases & (num_aliases - 1), 0);
935   CHECK_EQ(ring_buffer_size & (ring_buffer_size - 1), 0);
936 
937   const uptr granularity = GetMmapGranularity();
938   shadow_size = RoundUpTo(shadow_size, granularity);
939   CHECK_EQ(shadow_size & (shadow_size - 1), 0);
940 
941   const uptr alias_region_size = alias_size * num_aliases;
942   const uptr alignment =
943       2 * Max(Max(shadow_size, alias_region_size), ring_buffer_size);
944   const uptr left_padding = ring_buffer_size;
945 
946   const uptr right_size = alignment;
947   const uptr map_size = left_padding + 2 * alignment;
948 
949   const uptr map_start = reinterpret_cast<uptr>(MmapNoAccess(map_size));
950   CHECK_NE(map_start, static_cast<uptr>(-1));
951   const uptr right_start = RoundUpTo(map_start + left_padding, alignment);
952 
953   UnmapFromTo(map_start, right_start - left_padding);
954   UnmapFromTo(right_start + right_size, map_start + map_size);
955 
956   CreateAliases(right_start + right_size / 2, alias_size, num_aliases);
957 
958   return right_start;
959 }
960 
961 void InitializePlatformCommonFlags(CommonFlags *cf) {
962 #if SANITIZER_ANDROID
963   if (&__libc_get_static_tls_bounds == nullptr)
964     cf->detect_leaks = false;
965 #endif
966 }
967 
968 } // namespace __sanitizer
969 
970 #endif
971