| //===-- sanitizer_stacktrace.cc -------------------------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file is shared between AddressSanitizer and ThreadSanitizer |
| // run-time libraries. |
| //===----------------------------------------------------------------------===// |
| |
| #include "sanitizer_common.h" |
| #include "sanitizer_flags.h" |
| #include "sanitizer_stacktrace.h" |
| |
| namespace __sanitizer { |
| |
| uptr StackTrace::GetNextInstructionPc(uptr pc) { |
| #if defined(__mips__) |
| return pc + 8; |
| #elif defined(__powerpc__) |
| return pc + 4; |
| #else |
| return pc + 1; |
| #endif |
| } |
| |
| uptr StackTrace::GetCurrentPc() { |
| return GET_CALLER_PC(); |
| } |
| |
| void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) { |
| size = cnt + !!extra_top_pc; |
| CHECK_LE(size, kStackTraceMax); |
| internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0])); |
| if (extra_top_pc) |
| trace_buffer[cnt] = extra_top_pc; |
| top_frame_bp = 0; |
| } |
| |
| // In GCC on ARM bp points to saved lr, not fp, so we should check the next |
| // cell in stack to be a saved frame pointer. GetCanonicFrame returns the |
| // pointer to saved frame pointer in any case. |
| static inline uhwptr *GetCanonicFrame(uptr bp, |
| uptr stack_top, |
| uptr stack_bottom) { |
| #ifdef __arm__ |
| if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0; |
| uhwptr *bp_prev = (uhwptr *)bp; |
| if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev; |
| // The next frame pointer does not look right. This could be a GCC frame, step |
| // back by 1 word and try again. |
| if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom)) |
| return bp_prev - 1; |
| // Nope, this does not look right either. This means the frame after next does |
| // not have a valid frame pointer, but we can still extract the caller PC. |
| // Unfortunately, there is no way to decide between GCC and LLVM frame |
| // layouts. Assume LLVM. |
| return bp_prev; |
| #else |
| return (uhwptr*)bp; |
| #endif |
| } |
| |
| void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top, |
| uptr stack_bottom, u32 max_depth) { |
| const uptr kPageSize = GetPageSizeCached(); |
| CHECK_GE(max_depth, 2); |
| trace_buffer[0] = pc; |
| size = 1; |
| if (stack_top < 4096) return; // Sanity check for stack top. |
| uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom); |
| // Lowest possible address that makes sense as the next frame pointer. |
| // Goes up as we walk the stack. |
| uptr bottom = stack_bottom; |
| // Avoid infinite loop when frame == frame[0] by using frame > prev_frame. |
| while (IsValidFrame((uptr)frame, stack_top, bottom) && |
| IsAligned((uptr)frame, sizeof(*frame)) && |
| size < max_depth) { |
| #ifdef __powerpc__ |
| // PowerPC ABIs specify that the return address is saved at offset |
| // 16 of the *caller's* stack frame. Thus we must dereference the |
| // back chain to find the caller frame before extracting it. |
| uhwptr *caller_frame = (uhwptr*)frame[0]; |
| if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) || |
| !IsAligned((uptr)caller_frame, sizeof(uhwptr))) |
| break; |
| uhwptr pc1 = caller_frame[2]; |
| #elif defined(__s390__) |
| uhwptr pc1 = frame[14]; |
| #else |
| uhwptr pc1 = frame[1]; |
| #endif |
| // 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 (pc1 < kPageSize) |
| break; |
| if (pc1 != pc) { |
| trace_buffer[size++] = (uptr) pc1; |
| } |
| bottom = (uptr)frame; |
| frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom); |
| } |
| } |
| |
| static bool MatchPc(uptr cur_pc, uptr trace_pc, uptr threshold) { |
| return cur_pc - trace_pc <= threshold || trace_pc - cur_pc <= threshold; |
| } |
| |
| void BufferedStackTrace::PopStackFrames(uptr count) { |
| CHECK_LT(count, size); |
| size -= count; |
| for (uptr i = 0; i < size; ++i) { |
| trace_buffer[i] = trace_buffer[i + count]; |
| } |
| } |
| |
| uptr BufferedStackTrace::LocatePcInTrace(uptr pc) { |
| // Use threshold to find PC in stack trace, as PC we want to unwind from may |
| // slightly differ from return address in the actual unwinded stack trace. |
| const int kPcThreshold = 350; |
| for (uptr i = 0; i < size; ++i) { |
| if (MatchPc(pc, trace[i], kPcThreshold)) |
| return i; |
| } |
| return 0; |
| } |
| |
| } // namespace __sanitizer |