1 //===-- sanitizer_stacktrace.cpp ------------------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file is shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries.
11 //===----------------------------------------------------------------------===//
13 #include "sanitizer_common.h"
14 #include "sanitizer_flags.h"
15 #include "sanitizer_stacktrace.h"
17 namespace __sanitizer {
19 uptr StackTrace::GetNextInstructionPc(uptr pc) {
20 #if defined(__sparc__) || defined(__mips__)
22 #elif defined(__powerpc__) || defined(__arm__) || defined(__aarch64__)
29 uptr StackTrace::GetCurrentPc() {
30 return GET_CALLER_PC();
33 void BufferedStackTrace::Init(const uptr *pcs, uptr cnt, uptr extra_top_pc) {
34 size = cnt + !!extra_top_pc;
35 CHECK_LE(size, kStackTraceMax);
36 internal_memcpy(trace_buffer, pcs, cnt * sizeof(trace_buffer[0]));
38 trace_buffer[cnt] = extra_top_pc;
42 // Sparc implemention is in its own file.
43 #if !defined(__sparc__)
45 // In GCC on ARM bp points to saved lr, not fp, so we should check the next
46 // cell in stack to be a saved frame pointer. GetCanonicFrame returns the
47 // pointer to saved frame pointer in any case.
48 static inline uhwptr *GetCanonicFrame(uptr bp,
51 CHECK_GT(stack_top, stack_bottom);
53 if (!IsValidFrame(bp, stack_top, stack_bottom)) return 0;
54 uhwptr *bp_prev = (uhwptr *)bp;
55 if (IsValidFrame((uptr)bp_prev[0], stack_top, stack_bottom)) return bp_prev;
56 // The next frame pointer does not look right. This could be a GCC frame, step
57 // back by 1 word and try again.
58 if (IsValidFrame((uptr)bp_prev[-1], stack_top, stack_bottom))
60 // Nope, this does not look right either. This means the frame after next does
61 // not have a valid frame pointer, but we can still extract the caller PC.
62 // Unfortunately, there is no way to decide between GCC and LLVM frame
63 // layouts. Assume LLVM.
70 void BufferedStackTrace::UnwindFast(uptr pc, uptr bp, uptr stack_top,
71 uptr stack_bottom, u32 max_depth) {
72 // TODO(yln): add arg sanity check for stack_top/stack_bottom
73 CHECK_GE(max_depth, 2);
74 const uptr kPageSize = GetPageSizeCached();
77 if (stack_top < 4096) return; // Sanity check for stack top.
78 uhwptr *frame = GetCanonicFrame(bp, stack_top, stack_bottom);
79 // Lowest possible address that makes sense as the next frame pointer.
80 // Goes up as we walk the stack.
81 uptr bottom = stack_bottom;
82 // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
83 while (IsValidFrame((uptr)frame, stack_top, bottom) &&
84 IsAligned((uptr)frame, sizeof(*frame)) &&
87 // PowerPC ABIs specify that the return address is saved at offset
88 // 16 of the *caller's* stack frame. Thus we must dereference the
89 // back chain to find the caller frame before extracting it.
90 uhwptr *caller_frame = (uhwptr*)frame[0];
91 if (!IsValidFrame((uptr)caller_frame, stack_top, bottom) ||
92 !IsAligned((uptr)caller_frame, sizeof(uhwptr)))
94 uhwptr pc1 = caller_frame[2];
95 #elif defined(__s390__)
96 uhwptr pc1 = frame[14];
98 uhwptr pc1 = frame[1];
100 // Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
101 // x86_64) is invalid and stop unwinding here. If we're adding support for
102 // a platform where this isn't true, we need to reconsider this check.
106 trace_buffer[size++] = (uptr) pc1;
108 bottom = (uptr)frame;
109 frame = GetCanonicFrame((uptr)frame[0], stack_top, bottom);
113 #endif // !defined(__sparc__)
115 void BufferedStackTrace::PopStackFrames(uptr count) {
116 CHECK_LT(count, size);
118 for (uptr i = 0; i < size; ++i) {
119 trace_buffer[i] = trace_buffer[i + count];
123 static uptr Distance(uptr a, uptr b) { return a < b ? b - a : a - b; }
125 uptr BufferedStackTrace::LocatePcInTrace(uptr pc) {
127 for (uptr i = 1; i < size; ++i) {
128 if (Distance(trace[i], pc) < Distance(trace[best], pc)) best = i;
133 } // namespace __sanitizer