1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
//===-- 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;
}
// Check if given pointer points into allocated stack area.
static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
return frame > stack_bottom && frame < stack_top - 2 * sizeof (uhwptr);
}
// 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) {
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
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 = 320;
for (uptr i = 0; i < size; ++i) {
if (MatchPc(pc, trace[i], kPcThreshold))
return i;
}
return 0;
}
} // namespace __sanitizer
|
