| // -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- |
| // Copyright (c) 2005, Google Inc. |
| // All rights reserved. |
| // |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following disclaimer |
| // in the documentation and/or other materials provided with the |
| // distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived from |
| // this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
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| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| // --- |
| // Author: Sanjay Ghemawat |
| // |
| // Produce stack trace |
| |
| #ifndef BASE_STACKTRACE_X86_INL_H_ |
| #define BASE_STACKTRACE_X86_INL_H_ |
| // Note: this file is included into stacktrace.cc more than once. |
| // Anything that should only be defined once should be here: |
| |
| #include "config.h" |
| #include <stdlib.h> // for NULL |
| #include <assert.h> |
| #if defined(HAVE_SYS_UCONTEXT_H) |
| #include <sys/ucontext.h> |
| #elif defined(HAVE_UCONTEXT_H) |
| #include <ucontext.h> // for ucontext_t |
| #elif defined(HAVE_CYGWIN_SIGNAL_H) |
| // cygwin/signal.h has a buglet where it uses pthread_attr_t without |
| // #including <pthread.h> itself. So we have to do it. |
| # ifdef HAVE_PTHREAD |
| # include <pthread.h> |
| # endif |
| #include <cygwin/signal.h> |
| typedef ucontext ucontext_t; |
| #endif |
| #ifdef HAVE_STDINT_H |
| #include <stdint.h> // for uintptr_t |
| #endif |
| #ifdef HAVE_UNISTD_H |
| #include <unistd.h> |
| #endif |
| #ifdef HAVE_MMAP |
| #include <sys/mman.h> // for msync |
| #include "base/vdso_support.h" |
| #endif |
| |
| #include "gperftools/stacktrace.h" |
| |
| #if defined(__linux__) && defined(__i386__) && defined(__ELF__) && defined(HAVE_MMAP) |
| // Count "push %reg" instructions in VDSO __kernel_vsyscall(), |
| // preceding "syscall" or "sysenter". |
| // If __kernel_vsyscall uses frame pointer, answer 0. |
| // |
| // kMaxBytes tells how many instruction bytes of __kernel_vsyscall |
| // to analyze before giving up. Up to kMaxBytes+1 bytes of |
| // instructions could be accessed. |
| // |
| // Here are known __kernel_vsyscall instruction sequences: |
| // |
| // SYSENTER (linux-2.6.26/arch/x86/vdso/vdso32/sysenter.S). |
| // Used on Intel. |
| // 0xffffe400 <__kernel_vsyscall+0>: push %ecx |
| // 0xffffe401 <__kernel_vsyscall+1>: push %edx |
| // 0xffffe402 <__kernel_vsyscall+2>: push %ebp |
| // 0xffffe403 <__kernel_vsyscall+3>: mov %esp,%ebp |
| // 0xffffe405 <__kernel_vsyscall+5>: sysenter |
| // |
| // SYSCALL (see linux-2.6.26/arch/x86/vdso/vdso32/syscall.S). |
| // Used on AMD. |
| // 0xffffe400 <__kernel_vsyscall+0>: push %ebp |
| // 0xffffe401 <__kernel_vsyscall+1>: mov %ecx,%ebp |
| // 0xffffe403 <__kernel_vsyscall+3>: syscall |
| // |
| // i386 (see linux-2.6.26/arch/x86/vdso/vdso32/int80.S) |
| // 0xffffe400 <__kernel_vsyscall+0>: int $0x80 |
| // 0xffffe401 <__kernel_vsyscall+1>: ret |
| // |
| static const int kMaxBytes = 10; |
| |
| // We use assert()s instead of DCHECK()s -- this is too low level |
| // for DCHECK(). |
| |
| static int CountPushInstructions(const unsigned char *const addr) { |
| int result = 0; |
| for (int i = 0; i < kMaxBytes; ++i) { |
| if (addr[i] == 0x89) { |
| // "mov reg,reg" |
| if (addr[i + 1] == 0xE5) { |
| // Found "mov %esp,%ebp". |
| return 0; |
| } |
| ++i; // Skip register encoding byte. |
| } else if (addr[i] == 0x0F && |
| (addr[i + 1] == 0x34 || addr[i + 1] == 0x05)) { |
| // Found "sysenter" or "syscall". |
| return result; |
| } else if ((addr[i] & 0xF0) == 0x50) { |
| // Found "push %reg". |
| ++result; |
| } else if (addr[i] == 0xCD && addr[i + 1] == 0x80) { |
| // Found "int $0x80" |
| assert(result == 0); |
| return 0; |
| } else { |
| // Unexpected instruction. |
| assert(0 == "unexpected instruction in __kernel_vsyscall"); |
| return 0; |
| } |
| } |
| // Unexpected: didn't find SYSENTER or SYSCALL in |
| // [__kernel_vsyscall, __kernel_vsyscall + kMaxBytes) interval. |
| assert(0 == "did not find SYSENTER or SYSCALL in __kernel_vsyscall"); |
| return 0; |
| } |
| #endif |
| |
| // Given a pointer to a stack frame, locate and return the calling |
| // stackframe, or return NULL if no stackframe can be found. Perform sanity |
| // checks (the strictness of which is controlled by the boolean parameter |
| // "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned. |
| template<bool STRICT_UNWINDING, bool WITH_CONTEXT> |
| static void **NextStackFrame(void **old_sp, const void *uc) { |
| void **new_sp = (void **) *old_sp; |
| |
| #if defined(__linux__) && defined(__i386__) && defined(HAVE_VDSO_SUPPORT) |
| if (WITH_CONTEXT && uc != NULL) { |
| // How many "push %reg" instructions are there at __kernel_vsyscall? |
| // This is constant for a given kernel and processor, so compute |
| // it only once. |
| static int num_push_instructions = -1; // Sentinel: not computed yet. |
| // Initialize with sentinel value: __kernel_rt_sigreturn can not possibly |
| // be there. |
| static const unsigned char *kernel_rt_sigreturn_address = NULL; |
| static const unsigned char *kernel_vsyscall_address = NULL; |
| if (num_push_instructions == -1) { |
| base::VDSOSupport vdso; |
| if (vdso.IsPresent()) { |
| base::VDSOSupport::SymbolInfo rt_sigreturn_symbol_info; |
| base::VDSOSupport::SymbolInfo vsyscall_symbol_info; |
| if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.5", |
| STT_FUNC, &rt_sigreturn_symbol_info) || |
| !vdso.LookupSymbol("__kernel_vsyscall", "LINUX_2.5", |
| STT_FUNC, &vsyscall_symbol_info) || |
| rt_sigreturn_symbol_info.address == NULL || |
| vsyscall_symbol_info.address == NULL) { |
| // Unexpected: 32-bit VDSO is present, yet one of the expected |
| // symbols is missing or NULL. |
| assert(0 == "VDSO is present, but doesn't have expected symbols"); |
| num_push_instructions = 0; |
| } else { |
| kernel_rt_sigreturn_address = |
| reinterpret_cast<const unsigned char *>( |
| rt_sigreturn_symbol_info.address); |
| kernel_vsyscall_address = |
| reinterpret_cast<const unsigned char *>( |
| vsyscall_symbol_info.address); |
| num_push_instructions = |
| CountPushInstructions(kernel_vsyscall_address); |
| } |
| } else { |
| num_push_instructions = 0; |
| } |
| } |
| if (num_push_instructions != 0 && kernel_rt_sigreturn_address != NULL && |
| old_sp[1] == kernel_rt_sigreturn_address) { |
| const ucontext_t *ucv = static_cast<const ucontext_t *>(uc); |
| // This kernel does not use frame pointer in its VDSO code, |
| // and so %ebp is not suitable for unwinding. |
| void **const reg_ebp = |
| reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_EBP]); |
| const unsigned char *const reg_eip = |
| reinterpret_cast<unsigned char *>(ucv->uc_mcontext.gregs[REG_EIP]); |
| if (new_sp == reg_ebp && |
| kernel_vsyscall_address <= reg_eip && |
| reg_eip - kernel_vsyscall_address < kMaxBytes) { |
| // We "stepped up" to __kernel_vsyscall, but %ebp is not usable. |
| // Restore from 'ucv' instead. |
| void **const reg_esp = |
| reinterpret_cast<void **>(ucv->uc_mcontext.gregs[REG_ESP]); |
| // Check that alleged %esp is not NULL and is reasonably aligned. |
| if (reg_esp && |
| ((uintptr_t)reg_esp & (sizeof(reg_esp) - 1)) == 0) { |
| // Check that alleged %esp is actually readable. This is to prevent |
| // "double fault" in case we hit the first fault due to e.g. stack |
| // corruption. |
| // |
| // page_size is linker-initalized to avoid async-unsafe locking |
| // that GCC would otherwise insert (__cxa_guard_acquire etc). |
| static int page_size; |
| if (page_size == 0) { |
| // First time through. |
| page_size = getpagesize(); |
| } |
| void *const reg_esp_aligned = |
| reinterpret_cast<void *>( |
| (uintptr_t)(reg_esp + num_push_instructions - 1) & |
| ~(page_size - 1)); |
| if (msync(reg_esp_aligned, page_size, MS_ASYNC) == 0) { |
| // Alleged %esp is readable, use it for further unwinding. |
| new_sp = reinterpret_cast<void **>( |
| reg_esp[num_push_instructions - 1]); |
| } |
| } |
| } |
| } |
| } |
| #endif |
| |
| // Check that the transition from frame pointer old_sp to frame |
| // pointer new_sp isn't clearly bogus |
| if (STRICT_UNWINDING) { |
| // With the stack growing downwards, older stack frame must be |
| // at a greater address that the current one. |
| if (new_sp <= old_sp) return NULL; |
| // Assume stack frames larger than 100,000 bytes are bogus. |
| if ((uintptr_t)new_sp - (uintptr_t)old_sp > 100000) return NULL; |
| } else { |
| // In the non-strict mode, allow discontiguous stack frames. |
| // (alternate-signal-stacks for example). |
| if (new_sp == old_sp) return NULL; |
| if (new_sp > old_sp) { |
| // And allow frames upto about 1MB. |
| const uintptr_t delta = (uintptr_t)new_sp - (uintptr_t)old_sp; |
| const uintptr_t acceptable_delta = 1000000; |
| if (delta > acceptable_delta) { |
| return NULL; |
| } |
| } |
| } |
| if ((uintptr_t)new_sp & (sizeof(void *) - 1)) return NULL; |
| #ifdef __i386__ |
| // On 64-bit machines, the stack pointer can be very close to |
| // 0xffffffff, so we explicitly check for a pointer into the |
| // last two pages in the address space |
| if ((uintptr_t)new_sp >= 0xffffe000) return NULL; |
| #endif |
| #ifdef HAVE_MMAP |
| if (!STRICT_UNWINDING) { |
| // Lax sanity checks cause a crash on AMD-based machines with |
| // VDSO-enabled kernels. |
| // Make an extra sanity check to insure new_sp is readable. |
| // Note: NextStackFrame<false>() is only called while the program |
| // is already on its last leg, so it's ok to be slow here. |
| static int page_size = getpagesize(); |
| void *new_sp_aligned = (void *)((uintptr_t)new_sp & ~(page_size - 1)); |
| if (msync(new_sp_aligned, page_size, MS_ASYNC) == -1) |
| return NULL; |
| } |
| #endif |
| return new_sp; |
| } |
| |
| #endif // BASE_STACKTRACE_X86_INL_H_ |
| |
| // Note: this part of the file is included several times. |
| // Do not put globals below. |
| |
| // The following 4 functions are generated from the code below: |
| // GetStack{Trace,Frames}() |
| // GetStack{Trace,Frames}WithContext() |
| // |
| // These functions take the following args: |
| // void** result: the stack-trace, as an array |
| // int* sizes: the size of each stack frame, as an array |
| // (GetStackFrames* only) |
| // int max_depth: the size of the result (and sizes) array(s) |
| // int skip_count: how many stack pointers to skip before storing in result |
| // void* ucp: a ucontext_t* (GetStack{Trace,Frames}WithContext only) |
| |
| static int GET_STACK_TRACE_OR_FRAMES { |
| void **sp; |
| #if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2) || __llvm__ |
| // __builtin_frame_address(0) can return the wrong address on gcc-4.1.0-k8. |
| // It's always correct on llvm, and the techniques below aren't (in |
| // particular, llvm-gcc will make a copy of pcs, so it's not in sp[2]), |
| // so we also prefer __builtin_frame_address when running under llvm. |
| sp = reinterpret_cast<void**>(__builtin_frame_address(0)); |
| #elif defined(__i386__) |
| // Stack frame format: |
| // sp[0] pointer to previous frame |
| // sp[1] caller address |
| // sp[2] first argument |
| // ... |
| // NOTE: This will break under llvm, since result is a copy and not in sp[2] |
| sp = (void **)&result - 2; |
| #elif defined(__x86_64__) |
| unsigned long rbp; |
| // Move the value of the register %rbp into the local variable rbp. |
| // We need 'volatile' to prevent this instruction from getting moved |
| // around during optimization to before function prologue is done. |
| // An alternative way to achieve this |
| // would be (before this __asm__ instruction) to call Noop() defined as |
| // static void Noop() __attribute__ ((noinline)); // prevent inlining |
| // static void Noop() { asm(""); } // prevent optimizing-away |
| __asm__ volatile ("mov %%rbp, %0" : "=r" (rbp)); |
| // Arguments are passed in registers on x86-64, so we can't just |
| // offset from &result |
| sp = (void **) rbp; |
| #else |
| # error Using stacktrace_x86-inl.h on a non x86 architecture! |
| #endif |
| |
| skip_count++; // skip parent's frame due to indirection in stacktrace.cc |
| |
| int n = 0; |
| while (sp && n < max_depth) { |
| if (*(sp+1) == reinterpret_cast<void *>(0)) { |
| // In 64-bit code, we often see a frame that |
| // points to itself and has a return address of 0. |
| break; |
| } |
| #if !IS_WITH_CONTEXT |
| const void *const ucp = NULL; |
| #endif |
| void **next_sp = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(sp, ucp); |
| if (skip_count > 0) { |
| skip_count--; |
| } else { |
| result[n] = *(sp+1); |
| #if IS_STACK_FRAMES |
| if (next_sp > sp) { |
| sizes[n] = (uintptr_t)next_sp - (uintptr_t)sp; |
| } else { |
| // A frame-size of 0 is used to indicate unknown frame size. |
| sizes[n] = 0; |
| } |
| #endif |
| n++; |
| } |
| sp = next_sp; |
| } |
| return n; |
| } |
