//===-- sanitizer_unwind_linux_libcdep.cc ---------------------------------===// // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This file contains the unwind.h-based (aka "slow") stack unwinding routines // available to the tools on Linux, Android, NetBSD and FreeBSD. //===----------------------------------------------------------------------===// #include "sanitizer_platform.h" #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD #include "sanitizer_common.h" #include "sanitizer_stacktrace.h" #if SANITIZER_ANDROID #include // for dlopen() #endif #if SANITIZER_FREEBSD #define _GNU_SOURCE // to declare _Unwind_Backtrace() from #endif #include namespace __sanitizer { //------------------------- SlowUnwindStack ----------------------------------- typedef struct { uptr absolute_pc; uptr stack_top; uptr stack_size; } backtrace_frame_t; extern "C" { typedef void *(*acquire_my_map_info_list_func)(); typedef void (*release_my_map_info_list_func)(void *map); typedef sptr (*unwind_backtrace_signal_arch_func)( void *siginfo, void *sigcontext, void *map_info_list, backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth); acquire_my_map_info_list_func acquire_my_map_info_list; release_my_map_info_list_func release_my_map_info_list; unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch; } // extern "C" #if SANITIZER_ANDROID void SanitizerInitializeUnwinder() { if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return; // Pre-lollipop Android can not unwind through signal handler frames with // libgcc unwinder, but it has a libcorkscrew.so library with the necessary // workarounds. void *p = dlopen("libcorkscrew.so", RTLD_LAZY); if (!p) { VReport(1, "Failed to open libcorkscrew.so. You may see broken stack traces " "in SEGV reports."); return; } acquire_my_map_info_list = (acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list"); release_my_map_info_list = (release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list"); unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym( p, "unwind_backtrace_signal_arch"); if (!acquire_my_map_info_list || !release_my_map_info_list || !unwind_backtrace_signal_arch) { VReport(1, "Failed to find one of the required symbols in libcorkscrew.so. " "You may see broken stack traces in SEGV reports."); acquire_my_map_info_list = 0; unwind_backtrace_signal_arch = 0; release_my_map_info_list = 0; } } #endif #if defined(__arm__) && !SANITIZER_NETBSD // NetBSD uses dwarf EH #define UNWIND_STOP _URC_END_OF_STACK #define UNWIND_CONTINUE _URC_NO_REASON #else #define UNWIND_STOP _URC_NORMAL_STOP #define UNWIND_CONTINUE _URC_NO_REASON #endif uptr Unwind_GetIP(struct _Unwind_Context *ctx) { #if defined(__arm__) && !SANITIZER_MAC uptr val; _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE, 15 /* r15 = PC */, _UVRSD_UINT32, &val); CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed"); // Clear the Thumb bit. return val & ~(uptr)1; #else return _Unwind_GetIP(ctx); #endif } struct UnwindTraceArg { BufferedStackTrace *stack; u32 max_depth; }; _Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) { UnwindTraceArg *arg = (UnwindTraceArg*)param; CHECK_LT(arg->stack->size, arg->max_depth); uptr pc = Unwind_GetIP(ctx); const uptr kPageSize = GetPageSizeCached(); // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and // x86_64) is invalid and stop unwinding here. If we're adding support for // a platform where this isn't true, we need to reconsider this check. if (pc < kPageSize) return UNWIND_STOP; arg->stack->trace_buffer[arg->stack->size++] = pc; if (arg->stack->size == arg->max_depth) return UNWIND_STOP; return UNWIND_CONTINUE; } void BufferedStackTrace::SlowUnwindStack(uptr pc, u32 max_depth) { CHECK_GE(max_depth, 2); size = 0; UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)}; _Unwind_Backtrace(Unwind_Trace, &arg); // We need to pop a few frames so that pc is on top. uptr to_pop = LocatePcInTrace(pc); // trace_buffer[0] belongs to the current function so we always pop it, // unless there is only 1 frame in the stack trace (1 frame is always better // than 0!). // 1-frame stacks don't normally happen, but this depends on the actual // unwinder implementation (libgcc, libunwind, etc) which is outside of our // control. if (to_pop == 0 && size > 1) to_pop = 1; PopStackFrames(to_pop); trace_buffer[0] = pc; } void BufferedStackTrace::SlowUnwindStackWithContext(uptr pc, void *context, u32 max_depth) { CHECK_GE(max_depth, 2); if (!unwind_backtrace_signal_arch) { SlowUnwindStack(pc, max_depth); return; } void *map = acquire_my_map_info_list(); CHECK(map); InternalScopedBuffer frames(kStackTraceMax); // siginfo argument appears to be unused. sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map, frames.data(), /* ignore_depth */ 0, max_depth); release_my_map_info_list(map); if (res < 0) return; CHECK_LE((uptr)res, kStackTraceMax); size = 0; // +2 compensate for libcorkscrew unwinder returning addresses of call // instructions instead of raw return addresses. for (sptr i = 0; i < res; ++i) trace_buffer[size++] = frames[i].absolute_pc + 2; } } // namespace __sanitizer #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD