122 lines
4.0 KiB
C++
122 lines
4.0 KiB
C++
//===-- sanitizer_stacktrace.cc -------------------------------------------===//
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is shared between AddressSanitizer and ThreadSanitizer
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// run-time libraries.
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//===----------------------------------------------------------------------===//
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#include "sanitizer_common.h"
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#include "sanitizer_flags.h"
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#include "sanitizer_stacktrace.h"
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namespace __sanitizer {
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uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
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#if defined(__arm__)
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// Cancel Thumb bit.
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pc = pc & (~1);
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#endif
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#if defined(__powerpc__) || defined(__powerpc64__)
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// PCs are always 4 byte aligned.
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return pc - 4;
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#elif defined(__sparc__) || defined(__mips__)
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return pc - 8;
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#else
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return pc - 1;
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#endif
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}
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uptr StackTrace::GetCurrentPc() {
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return GET_CALLER_PC();
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}
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void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {
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size = cnt + !!extra_top_pc;
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CHECK_LE(size, kStackTraceMax);
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internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));
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if (extra_top_pc)
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trace_buffer[cnt] = extra_top_pc;
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top_frame_bp = 0;
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}
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// Check if given pointer points into allocated stack area.
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static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
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return frame > stack_bottom && frame < stack_top - 2 * sizeof (uhwptr);
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}
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// In GCC on ARM bp points to saved lr, not fp, so we should check the next
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// cell in stack to be a saved frame pointer. GetCanonicFrame returns the
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// pointer to saved frame pointer in any case.
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static inline uhwptr *GetCanonicFrame(uptr bp,
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uptr stack_top,
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uptr stack_bottom) {
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#ifdef __arm__
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if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;
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uhwptr *bp_prev = (uhwptr *)bp;
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if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;
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// The next frame pointer does not look right. This could be a GCC frame, step
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// back by 1 word and try again.
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if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))
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return bp_prev - 1;
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// Nope, this does not look right either. This means the frame after next does
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// not have a valid frame pointer, but we can still extract the caller PC.
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// Unfortunately, there is no way to decide between GCC and LLVM frame
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// layouts. Assume LLVM.
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return bp_prev;
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#else
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return (uhwptr*)bp;
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#endif
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}
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void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
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uptr stack_bottom, uptr max_depth) {
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CHECK_GE(max_depth, 2);
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trace_buffer[0] = pc;
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size = 1;
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if (stack_top < 4096) return; // Sanity check for stack top.
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uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);
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// Lowest possible address that makes sense as the next frame pointer.
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// Goes up as we walk the stack.
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uptr bottom = stack_bottom;
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// Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
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while (IsValidFrame((uptr)frame, stack_top, bottom) &&
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IsAligned((uptr)frame, sizeof(*frame)) &&
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size < max_depth) {
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uhwptr pc1 = frame[1];
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if (pc1 != pc) {
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trace_buffer[size++] = (uptr) pc1;
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}
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bottom = (uptr)frame;
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frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom);
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}
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}
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static bool MatchPc(uptr cur_pc, uptr trace_pc, uptr threshold) {
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return cur_pc - trace_pc <= threshold || trace_pc - cur_pc <= threshold;
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}
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void BufferedStackTrace::PopStackFrames(uptr count) {
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CHECK_LT(count, size);
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size -= count;
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for (uptr i = 0; i < size; ++i) {
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trace_buffer[i] = trace_buffer[i + count];
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}
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}
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uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {
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// Use threshold to find PC in stack trace, as PC we want to unwind from may
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// slightly differ from return address in the actual unwinded stack trace.
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const int kPcThreshold = 288;
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for (uptr i = 0; i < size; ++i) {
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if (MatchPc(pc, trace[i], kPcThreshold))
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return i;
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}
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return 0;
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}
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} // namespace __sanitizer
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