diff options
Diffstat (limited to 'abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc')
| -rw-r--r-- | abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc | 118 |
1 files changed, 82 insertions, 36 deletions
diff --git a/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc b/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc index 14a76f1..3f08716 100644 --- a/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc +++ b/abseil-cpp/absl/debugging/internal/stacktrace_aarch64-inl.inc @@ -13,13 +13,18 @@ #include <cassert> #include <cstdint> #include <iostream> +#include <limits> #include "absl/base/attributes.h" #include "absl/debugging/internal/address_is_readable.h" #include "absl/debugging/internal/vdso_support.h" // a no-op on non-elf or non-glibc systems #include "absl/debugging/stacktrace.h" -static const uintptr_t kUnknownFrameSize = 0; +static const size_t kUnknownFrameSize = 0; +// Stack end to use when we don't know the actual stack end +// (effectively just the end of address space). +constexpr uintptr_t kUnknownStackEnd = + std::numeric_limits<size_t>::max() - sizeof(void *); #if defined(__linux__) // Returns the address of the VDSO __kernel_rt_sigreturn function, if present. @@ -37,8 +42,11 @@ static const unsigned char* GetKernelRtSigreturnAddress() { absl::debugging_internal::VDSOSupport vdso; if (vdso.IsPresent()) { absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info; - if (!vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.6.39", STT_FUNC, - &symbol_info) || + auto lookup = [&](int type) { + return vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_2.6.39", type, + &symbol_info); + }; + if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) || symbol_info.address == nullptr) { // Unexpected: VDSO is present, yet the expected symbol is missing // or null. @@ -62,11 +70,12 @@ static const unsigned char* GetKernelRtSigreturnAddress() { // Compute the size of a stack frame in [low..high). We assume that // low < high. Return size of kUnknownFrameSize. template<typename T> -static inline uintptr_t ComputeStackFrameSize(const T* low, - const T* high) { +static inline size_t ComputeStackFrameSize(const T* low, + const T* high) { const char* low_char_ptr = reinterpret_cast<const char *>(low); const char* high_char_ptr = reinterpret_cast<const char *>(high); - return low < high ? high_char_ptr - low_char_ptr : kUnknownFrameSize; + return low < high ? static_cast<size_t>(high_char_ptr - low_char_ptr) + : kUnknownFrameSize; } // Given a pointer to a stack frame, locate and return the calling @@ -75,8 +84,9 @@ static inline uintptr_t ComputeStackFrameSize(const T* low, // "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned. template<bool STRICT_UNWINDING, bool WITH_CONTEXT> ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack. -ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack. -static void **NextStackFrame(void **old_frame_pointer, const void *uc) { +ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack. +static void **NextStackFrame(void **old_frame_pointer, const void *uc, + size_t stack_low, size_t stack_high) { void **new_frame_pointer = reinterpret_cast<void**>(*old_frame_pointer); bool check_frame_size = true; @@ -90,16 +100,21 @@ static void **NextStackFrame(void **old_frame_pointer, const void *uc) { void **const pre_signal_frame_pointer = reinterpret_cast<void **>(ucv->uc_mcontext.regs[29]); + // The most recent signal always needs special handling to find the frame + // pointer, but a nested signal does not. If pre_signal_frame_pointer is + // earlier in the stack than the old_frame_pointer, then use it. If it is + // later, then we have already unwound through it and it needs no special + // handling. + if (pre_signal_frame_pointer >= old_frame_pointer) { + new_frame_pointer = pre_signal_frame_pointer; + } // Check that alleged frame pointer is actually readable. This is to // prevent "double fault" in case we hit the first fault due to e.g. // stack corruption. if (!absl::debugging_internal::AddressIsReadable( - pre_signal_frame_pointer)) + new_frame_pointer)) return nullptr; - // Alleged frame pointer is readable, use it for further unwinding. - new_frame_pointer = pre_signal_frame_pointer; - // Skip frame size check if we return from a signal. We may be using a // an alternate stack for signals. check_frame_size = false; @@ -107,18 +122,36 @@ static void **NextStackFrame(void **old_frame_pointer, const void *uc) { } #endif - // aarch64 ABI requires stack pointer to be 16-byte-aligned. - if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 15) != 0) + // The frame pointer should be 8-byte aligned. + if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 7) != 0) return nullptr; // Check frame size. In strict mode, we assume frames to be under // 100,000 bytes. In non-strict mode, we relax the limit to 1MB. if (check_frame_size) { - const uintptr_t max_size = STRICT_UNWINDING ? 100000 : 1000000; - const uintptr_t frame_size = + const size_t max_size = STRICT_UNWINDING ? 100000 : 1000000; + const size_t frame_size = ComputeStackFrameSize(old_frame_pointer, new_frame_pointer); - if (frame_size == kUnknownFrameSize || frame_size > max_size) - return nullptr; + if (frame_size == kUnknownFrameSize) + return nullptr; + // A very large frame may mean corrupt memory or an erroneous frame + // pointer. But also maybe just a plain-old large frame. Assume that if the + // frame is within the known stack, then it is valid. + if (frame_size > max_size) { + if (stack_high < kUnknownStackEnd && + static_cast<size_t>(getpagesize()) < stack_low) { + const uintptr_t new_fp_u = + reinterpret_cast<uintptr_t>(new_frame_pointer); + // Stack bounds are known. + if (!(stack_low < new_fp_u && new_fp_u <= stack_high)) { + // new_frame_pointer is not within the known stack. + return nullptr; + } + } else { + // Stack bounds are unknown, prefer truncated stack to possible crash. + return nullptr; + } + } } return new_frame_pointer; @@ -134,51 +167,64 @@ static int UnwindImpl(void** result, int* sizes, int max_depth, int skip_count, #else # error reading stack point not yet supported on this platform. #endif - skip_count++; // Skip the frame for this function. int n = 0; + // Assume that the first page is not stack. + size_t stack_low = static_cast<size_t>(getpagesize()); + size_t stack_high = kUnknownStackEnd; + // The frame pointer points to low address of a frame. The first 64-bit // word of a frame points to the next frame up the call chain, which normally // is just after the high address of the current frame. The second word of - // a frame contains return adress of to the caller. To find a pc value + // a frame contains return address of to the caller. To find a pc value // associated with the current frame, we need to go down a level in the call // chain. So we remember return the address of the last frame seen. This // does not work for the first stack frame, which belongs to UnwindImp() but // we skip the frame for UnwindImp() anyway. void* prev_return_address = nullptr; + // The nth frame size is the difference between the nth frame pointer and the + // the frame pointer below it in the call chain. There is no frame below the + // leaf frame, but this function is the leaf anyway, and we skip it. + void** prev_frame_pointer = nullptr; - while (frame_pointer && n < max_depth) { - // The absl::GetStackFrames routine is called when we are in some - // informational context (the failure signal handler for example). - // Use the non-strict unwinding rules to produce a stack trace - // that is as complete as possible (even if it contains a few bogus - // entries in some rare cases). - void **next_frame_pointer = - NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp); - + while (frame_pointer && n < max_depth) { if (skip_count > 0) { skip_count--; } else { result[n] = prev_return_address; if (IS_STACK_FRAMES) { - sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer); + sizes[n] = static_cast<int>( + ComputeStackFrameSize(prev_frame_pointer, frame_pointer)); } n++; } prev_return_address = frame_pointer[1]; - frame_pointer = next_frame_pointer; + prev_frame_pointer = frame_pointer; + // The absl::GetStackFrames routine is called when we are in some + // informational context (the failure signal handler for example). + // Use the non-strict unwinding rules to produce a stack trace + // that is as complete as possible (even if it contains a few bogus + // entries in some rare cases). + frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>( + frame_pointer, ucp, stack_low, stack_high); } + if (min_dropped_frames != nullptr) { // Implementation detail: we clamp the max of frames we are willing to // count, so as not to spend too much time in the loop below. const int kMaxUnwind = 200; - int j = 0; - for (; frame_pointer != nullptr && j < kMaxUnwind; j++) { - frame_pointer = - NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp); + int num_dropped_frames = 0; + for (int j = 0; frame_pointer != nullptr && j < kMaxUnwind; j++) { + if (skip_count > 0) { + skip_count--; + } else { + num_dropped_frames++; + } + frame_pointer = NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>( + frame_pointer, ucp, stack_low, stack_high); } - *min_dropped_frames = j; + *min_dropped_frames = num_dropped_frames; } return n; } |