1 //===-- sanitizer_stacktrace.cc -------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is shared between AddressSanitizer and ThreadSanitizer
11 // run-time libraries.
12 //===----------------------------------------------------------------------===//
14 #include "sanitizer_common.h"
15 #include "sanitizer_flags.h"
16 #include "sanitizer_stacktrace.h"
18 namespace __sanitizer {
20 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
25 #if defined(__powerpc__) || defined(__powerpc64__)
26 // PCs are always 4 byte aligned.
28 #elif defined(__sparc__) || defined(__mips__)
35 uptr StackTrace::GetNextInstructionPc(uptr pc) {
43 uptr StackTrace::GetCurrentPc() {
44 return GET_CALLER_PC();
47 void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {
48 size = cnt + !!extra_top_pc;
49 CHECK_LE(size, kStackTraceMax);
50 internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));
52 trace_buffer[cnt] = extra_top_pc;
56 // Check if given pointer points into allocated stack area.
57 static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
58 return frame > stack_bottom && frame < stack_top - 2 * sizeof (uhwptr);
61 // In GCC on ARM bp points to saved lr, not fp, so we should check the next
62 // cell in stack to be a saved frame pointer. GetCanonicFrame returns the
63 // pointer to saved frame pointer in any case.
64 static inline uhwptr *GetCanonicFrame(uptr bp,
68 if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;
69 uhwptr *bp_prev = (uhwptr *)bp;
70 if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;
71 // The next frame pointer does not look right. This could be a GCC frame, step
72 // back by 1 word and try again.
73 if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))
75 // Nope, this does not look right either. This means the frame after next does
76 // not have a valid frame pointer, but we can still extract the caller PC.
77 // Unfortunately, there is no way to decide between GCC and LLVM frame
78 // layouts. Assume LLVM.
85 void BufferedStackTrace::FastUnwindStack(uptr pc, uptr bp, uptr stack_top,
86 uptr stack_bottom, uptr max_depth) {
87 CHECK_GE(max_depth, 2);
90 if (stack_top < 4096) return; // Sanity check for stack top.
91 uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);
92 // Lowest possible address that makes sense as the next frame pointer.
93 // Goes up as we walk the stack.
94 uptr bottom = stack_bottom;
95 // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
96 while (IsValidFrame((uptr)frame, stack_top, bottom) &&
97 IsAligned((uptr)frame, sizeof(*frame)) &&
99 uhwptr pc1 = frame[1];
101 trace_buffer[size++] = (uptr) pc1;
103 bottom = (uptr)frame;
104 frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom);
108 static bool MatchPc(uptr cur_pc, uptr trace_pc, uptr threshold) {
109 return cur_pc - trace_pc <= threshold || trace_pc - cur_pc <= threshold;
112 void BufferedStackTrace::PopStackFrames(uptr count) {
113 CHECK_LT(count, size);
115 for (uptr i = 0; i < size; ++i) {
116 trace_buffer[i] = trace_buffer[i + count];
120 uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {
121 // Use threshold to find PC in stack trace, as PC we want to unwind from may
122 // slightly differ from return address in the actual unwinded stack trace.
123 const int kPcThreshold = 288;
124 for (uptr i = 0; i < size; ++i) {
125 if (MatchPc(pc, trace[i], kPcThreshold))
131 } // namespace __sanitizer