third_party/tcmalloc/vendor/src/stacktrace_x86-inl.h

   1 // Copyright (c) 2005, Google Inc.
   2 // All rights reserved.
   3 //
   4 // Redistribution and use in source and binary forms, with or without
   5 // modification, are permitted provided that the following conditions are
   6 // met:
   7 //
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   9 // notice, this list of conditions and the following disclaimer.
  10 //     * Redistributions in binary form must reproduce the above
  11 // copyright notice, this list of conditions and the following disclaimer
  12 // in the documentation and/or other materials provided with the
  13 // distribution.
  14 //     * Neither the name of Google Inc. nor the names of its
  15 // contributors may be used to endorse or promote products derived from
  16 // this software without specific prior written permission.
  17 //
  18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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  27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30 // ---
  31 // Author: Sanjay Ghemawat
  32 //
  33 // Produce stack trace
  34
  35 #ifndef BASE_STACKTRACE_X86_INL_H_
  36 #define BASE_STACKTRACE_X86_INL_H_
  37 // Note: this file is included into stacktrace.cc more than once.
  38 // Anything that should only be defined once should be here:
  39
  40 #include "config.h"
  41 #include <stdlib.h>   // for NULL
  42 #include <assert.h>
  43 #if defined(HAVE_SYS_UCONTEXT_H)
  44 #include <sys/ucontext.h>
  45 #elif defined(HAVE_UCONTEXT_H)
  46 #include <ucontext.h>  // for ucontext_t
  47 #elif defined(HAVE_CYGWIN_SIGNAL_H)
  48 // cygwin/signal.h has a buglet where it uses pthread_attr_t without
  49 // #including <pthread.h> itself.  So we have to do it.
  50 # ifdef HAVE_PTHREAD
  51 # include <pthread.h>
  52 # endif
  53 #include <cygwin/signal.h>
  54 typedef ucontext ucontext_t;
  55 #endif
  56 #ifdef HAVE_STDINT_H
  57 #include <stdint.h>   // for uintptr_t
  58 #endif
  59 #ifdef HAVE_UNISTD_H
  60 #include <unistd.h>
  61 #endif
  62 #ifdef HAVE_MMAP
  63 #include <sys/mman.h> // for msync
  64 #include "base/vdso_support.h"
  65 #endif
  66
  67 #include "gperftools/stacktrace.h"
  68
  69 #if defined(__linux__) && defined(__i386__) && defined(__ELF__) && defined(HAVE_MMAP)
  70 // Count "push %reg" instructions in VDSO __kernel_vsyscall(),
  71 // preceeding "syscall" or "sysenter".
  72 // If __kernel_vsyscall uses frame pointer, answer 0.
  73 //
  74 // kMaxBytes tells how many instruction bytes of __kernel_vsyscall
  75 // to analyze before giving up. Up to kMaxBytes+1 bytes of
  76 // instructions could be accessed.
  77 //
  78 // Here are known __kernel_vsyscall instruction sequences:
  79 //
  80 // SYSENTER (linux-2.6.26/arch/x86/vdso/vdso32/sysenter.S).
  81 // Used on Intel.
  82 //  0xffffe400 <__kernel_vsyscall+0>:       push   %ecx
  83 //  0xffffe401 <__kernel_vsyscall+1>:       push   %edx
  84 //  0xffffe402 <__kernel_vsyscall+2>:       push   %ebp
  85 //  0xffffe403 <__kernel_vsyscall+3>:       mov    %esp,%ebp
  86 //  0xffffe405 <__kernel_vsyscall+5>:       sysenter
  87 //
  88 // SYSCALL (see linux-2.6.26/arch/x86/vdso/vdso32/syscall.S).
  89 // Used on AMD.
  90 //  0xffffe400 <__kernel_vsyscall+0>:       push   %ebp
  91 //  0xffffe401 <__kernel_vsyscall+1>:       mov    %ecx,%ebp
  92 //  0xffffe403 <__kernel_vsyscall+3>:       syscall
  93 //
  94 // i386 (see linux-2.6.26/arch/x86/vdso/vdso32/int80.S)
  95 //  0xffffe400 <__kernel_vsyscall+0>:       int $0x80
  96 //  0xffffe401 <__kernel_vsyscall+1>:       ret
  97 //
  98 static const int kMaxBytes = 10;
  99
 100 // We use assert()s instead of DCHECK()s -- this is too low level
 101 // for DCHECK().
 102
 103 static int CountPushInstructions(const unsigned char *const addr) {
 104   int result = 0;
 105   for (int i = 0; i < kMaxBytes; ++i) {
 106     if (addr[i] == 0x89) {
 107       // "mov reg,reg"
 108       if (addr[i + 1] == 0xE5) {
 109         // Found "mov %esp,%ebp".
 110         return 0;
 111       }
 112       ++i;  // Skip register encoding byte.
 113     } else if (addr[i] == 0x0F &&
 114                (addr[i + 1] == 0x34 || addr[i + 1] == 0x05)) {
 115       // Found "sysenter" or "syscall".
 116       return result;
 117     } else if ((addr[i] & 0xF0) == 0x50) {
 118       // Found "push %reg".
 119       ++result;
 120     } else if (addr[i] == 0xCD && addr[i + 1] == 0x80) {
 121       // Found "int $0x80"
 122       assert(result == 0);
 123       return 0;
 124     } else {
 125       // Unexpected instruction.
 126       assert(0 == "unexpected instruction in __kernel_vsyscall");
 127       return 0;
 128     }
 129   }
 130   // Unexpected: didn't find SYSENTER or SYSCALL in
 131   // [__kernel_vsyscall, __kernel_vsyscall + kMaxBytes) interval.
 132   assert(0 == "did not find SYSENTER or SYSCALL in __kernel_vsyscall");
 133   return 0;
 134 }
 135 #endif
 136
 137 // Given a pointer to a stack frame, locate and return the calling
 138 // stackframe, or return NULL if no stackframe can be found. Perform sanity
 139 // checks (the strictness of which is controlled by the boolean parameter
 140 // "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
 141 template<bool STRICT_UNWINDING, bool WITH_CONTEXT>
 142 static void **NextStackFrame(void **old_sp, const void *uc) {
 143   void **new_sp = (void **) *old_sp;
 144
 145 #if defined(__linux__) && defined(__i386__) && defined(HAVE_VDSO_SUPPORT)
 146   if (WITH_CONTEXT && uc != NULL) {
 147     // How many "push %reg" instructions are there at __kernel_vsyscall?
 148     // This is constant for a given kernel and processor, so compute
 149     // it only once.
 150     static int num_push_instructions = -1;  // Sentinel: not computed yet.
 151     // Initialize with sentinel value: __kernel_rt_sigreturn can not possibly
 152     // be there.
 153     static const unsigned char *kernel_rt_sigreturn_address = NULL;
 154     static const unsigned char *kernel_vsyscall_address = NULL;
 155     if (num_push_instructions == -1) {
 156       base::VDSOSupport vdso;
 157       if (vdso.IsPresent()) {
 158         base::VDSOSupport::SymbolInfo rt_sigreturn_symbol_info;
 159         base::VDSOSupport::SymbolInfo vsyscall_symbol_info;
 160         if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.5",
 161                                STT_FUNC, &rt_sigreturn_symbol_info) ||
 162             !vdso.LookupSymbol("__kernel_vsyscall", "LINUX_2.5",
 163                                STT_FUNC, &vsyscall_symbol_info) ||
 164             rt_sigreturn_symbol_info.address == NULL ||
 165             vsyscall_symbol_info.address == NULL) {
 166           // Unexpected: 32-bit VDSO is present, yet one of the expected
 167           // symbols is missing or NULL.
 168           assert(0 == "VDSO is present, but doesn't have expected symbols");
 169           num_push_instructions = 0;
 170         } else {
 171           kernel_rt_sigreturn_address =
 172               reinterpret_cast<const unsigned char *>(
 173                   rt_sigreturn_symbol_info.address);
 174           kernel_vsyscall_address =
 175               reinterpret_cast<const unsigned char *>(
 176                   vsyscall_symbol_info.address);
 177           num_push_instructions =
 178               CountPushInstructions(kernel_vsyscall_address);
 179         }
 180       } else {
 181         num_push_instructions = 0;
 182       }
 183     }
 184     if (num_push_instructions != 0 && kernel_rt_sigreturn_address != NULL &&
 185         old_sp[1] == kernel_rt_sigreturn_address) {
 186       const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
 187       // This kernel does not use frame pointer in its VDSO code,
 188       // and so %ebp is not suitable for unwinding.
 189       void **const reg_ebp =
 190           reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_EBP]);
 191       const unsigned char *const reg_eip =
 192           reinterpret_cast<unsigned char *>(ucv->uc_mcontext.gregs[REG_EIP]);
 193       if (new_sp == reg_ebp &&
 194           kernel_vsyscall_address <= reg_eip &&
 195           reg_eip - kernel_vsyscall_address < kMaxBytes) {
 196         // We "stepped up" to __kernel_vsyscall, but %ebp is not usable.
 197         // Restore from 'ucv' instead.
 198         void **const reg_esp =
 199             reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_ESP]);
 200         // Check that alleged %esp is not NULL and is reasonably aligned.
 201         if (reg_esp &&
 202             ((uintptr_t)reg_esp & (sizeof(reg_esp) - 1)) == 0) {
 203           // Check that alleged %esp is actually readable. This is to prevent
 204           // "double fault" in case we hit the first fault due to e.g. stack
 205           // corruption.
 206           //
 207           // page_size is linker-initalized to avoid async-unsafe locking
 208           // that GCC would otherwise insert (__cxa_guard_acquire etc).
 209           static int page_size;
 210           if (page_size == 0) {
 211             // First time through.
 212             page_size = getpagesize();
 213           }
 214           void *const reg_esp_aligned =
 215               reinterpret_cast<void *>(
 216                   (uintptr_t)(reg_esp + num_push_instructions - 1) &
 217                   ~(page_size - 1));
 218           if (msync(reg_esp_aligned, page_size, MS_ASYNC) == 0) {
 219             // Alleged %esp is readable, use it for further unwinding.
 220             new_sp = reinterpret_cast<void **>(
 221                 reg_esp[num_push_instructions - 1]);
 222           }
 223         }
 224       }
 225     }
 226   }
 227 #endif
 228
 229   // Check that the transition from frame pointer old_sp to frame
 230   // pointer new_sp isn't clearly bogus
 231   if (STRICT_UNWINDING) {
 232     // With the stack growing downwards, older stack frame must be
 233     // at a greater address that the current one.
 234     if (new_sp <= old_sp) return NULL;
 235     // Assume stack frames larger than 100,000 bytes are bogus.
 236     if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return NULL;
 237   } else {
 238     // In the non-strict mode, allow discontiguous stack frames.
 239     // (alternate-signal-stacks for example).
 240     if (new_sp == old_sp) return NULL;
 241     if (new_sp > old_sp) {
 242       // And allow frames upto about 1MB.
 243       const uintptr_t delta = (uintptr_t)new_sp - (uintptr_t)old_sp;
 244       const uintptr_t acceptable_delta = 1000000;
 245       if (delta > acceptable_delta) {
 246         return NULL;
 247       }
 248     }
 249   }
 250   if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return NULL;
 251 #ifdef __i386__
 252   // On 64-bit machines, the stack pointer can be very close to
 253   // 0xffffffff, so we explicitly check for a pointer into the
 254   // last two pages in the address space
 255   if ((uintptr_t)new_sp >= 0xffffe000) return NULL;
 256 #endif
 257 #ifdef HAVE_MMAP
 258   if (!STRICT_UNWINDING) {
 259     // Lax sanity checks cause a crash on AMD-based machines with
 260     // VDSO-enabled kernels.
 261     // Make an extra sanity check to insure new_sp is readable.
 262     // Note: NextStackFrame<false>() is only called while the program
 263     //       is already on its last leg, so it's ok to be slow here.
 264     static int page_size = getpagesize();
 265     void *new_sp_aligned = (void *)((uintptr_t)new_sp & ~(page_size - 1));
 266     if (msync(new_sp_aligned, page_size, MS_ASYNC) == -1)
 267       return NULL;
 268   }
 269 #endif
 270   return new_sp;
 271 }
 272
 273 #endif  // BASE_STACKTRACE_X86_INL_H_
 274
 275 // Note: this part of the file is included several times.
 276 // Do not put globals below.
 277
 278 // The following 4 functions are generated from the code below:
 279 //   GetStack{Trace,Frames}()
 280 //   GetStack{Trace,Frames}WithContext()
 281 //
 282 // These functions take the following args:
 283 //   void** result: the stack-trace, as an array
 284 //   int* sizes: the size of each stack frame, as an array
 285 //               (GetStackFrames* only)
 286 //   int max_depth: the size of the result (and sizes) array(s)
 287 //   int skip_count: how many stack pointers to skip before storing in result
 288 //   void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only)
 289
 290 int GET_STACK_TRACE_OR_FRAMES {
 291   void **sp;
 292 #if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2) || __llvm__
 293   // __builtin_frame_address(0) can return the wrong address on gcc-4.1.0-k8.
 294   // It's always correct on llvm, and the techniques below aren't (in
 295   // particular, llvm-gcc will make a copy of pcs, so it's not in sp[2]),
 296   // so we also prefer __builtin_frame_address when running under llvm.
 297   sp = reinterpret_cast<void**>(__builtin_frame_address(0));
 298 #elif defined(__i386__)
 299   // Stack frame format:
 300   //    sp[0]   pointer to previous frame
 301   //    sp[1]   caller address
 302   //    sp[2]   first argument
 303   //    ...
 304   // NOTE: This will break under llvm, since result is a copy and not in sp[2]
 305   sp = (void **)&result - 2;
 306 #elif defined(__x86_64__)
 307   unsigned long rbp;
 308   // Move the value of the register %rbp into the local variable rbp.
 309   // We need 'volatile' to prevent this instruction from getting moved
 310   // around during optimization to before function prologue is done.
 311   // An alternative way to achieve this
 312   // would be (before this __asm__ instruction) to call Noop() defined as
 313   //   static void Noop() __attribute__ ((noinline));  // prevent inlining
 314   //   static void Noop() { asm(""); }  // prevent optimizing-away
 315   __asm__ volatile ("mov %%rbp, %0" : "=r" (rbp));
 316   // Arguments are passed in registers on x86-64, so we can't just
 317   // offset from &result
 318   sp = (void **) rbp;
 319 #else
 320 # error Using stacktrace_x86-inl.h on a non x86 architecture!
 321 #endif
 322
 323   int n = 0;
 324   while (sp && n < max_depth) {
 325     if (*(sp+1) == reinterpret_cast<void *>(0)) {
 326       // In 64-bit code, we often see a frame that
 327       // points to itself and has a return address of 0.
 328       break;
 329     }
 330 #if !IS_WITH_CONTEXT
 331     const void *const ucp = NULL;
 332 #endif
 333     void **next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp);
 334     if (skip_count > 0) {
 335       skip_count--;
 336     } else {
 337       result[n] = *(sp+1);
 338 #if IS_STACK_FRAMES
 339       if (next_sp > sp) {
 340         sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp;
 341       } else {
 342         // A frame-size of 0 is used to indicate unknown frame size.
 343         sizes[n] = 0;
 344       }
 345 #endif
 346       n++;
 347     }
 348     sp = next_sp;
 349   }
 350   return n;
 351 }