1 //===-- backtrace_sanitizer_common.cpp --------------------------*- C++ -*-===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include <assert.h>
10 #include <stddef.h>
11 #include <stdint.h>
12 #include <string.h>
13
14 #include "gwp_asan/optional/backtrace.h"
15 #include "gwp_asan/options.h"
16 #include "sanitizer_common/sanitizer_common.h"
17 #include "sanitizer_common/sanitizer_flag_parser.h"
18 #include "sanitizer_common/sanitizer_flags.h"
19 #include "sanitizer_common/sanitizer_stacktrace.h"
20
UnwindImpl(uptr pc,uptr bp,void * context,bool request_fast,u32 max_depth)21 void __sanitizer::BufferedStackTrace::UnwindImpl(uptr pc, uptr bp,
22 void *context,
23 bool request_fast,
24 u32 max_depth) {
25 if (!StackTrace::WillUseFastUnwind(request_fast))
26 return Unwind(max_depth, pc, 0, context, 0, 0, false);
27
28 uptr top = 0;
29 uptr bottom = 0;
30 GetThreadStackTopAndBottom(/*at_initialization*/ false, &top, &bottom);
31
32 return Unwind(max_depth, pc, bp, context, top, bottom, request_fast);
33 }
34
35 namespace {
BacktraceCommon(uintptr_t * TraceBuffer,size_t Size,void * Context)36 size_t BacktraceCommon(uintptr_t *TraceBuffer, size_t Size, void *Context) {
37 // Use the slow sanitizer unwinder in the segv handler. Fast frame pointer
38 // unwinders can end up dropping frames because the kernel sigreturn() frame's
39 // return address is the return address at time of fault. This has the result
40 // of never actually capturing the PC where the signal was raised.
41 bool UseFastUnwind = (Context == nullptr);
42
43 __sanitizer::BufferedStackTrace Trace;
44 Trace.Reset();
45 if (Size > __sanitizer::kStackTraceMax)
46 Size = __sanitizer::kStackTraceMax;
47
48 Trace.Unwind((__sanitizer::uptr)__builtin_return_address(0),
49 (__sanitizer::uptr)__builtin_frame_address(0), Context,
50 UseFastUnwind, Size - 1);
51
52 memcpy(TraceBuffer, Trace.trace, Trace.size * sizeof(uintptr_t));
53 return Trace.size;
54 }
55
Backtrace(uintptr_t * TraceBuffer,size_t Size)56 size_t Backtrace(uintptr_t *TraceBuffer, size_t Size) {
57 return BacktraceCommon(TraceBuffer, Size, nullptr);
58 }
59
SegvBacktrace(uintptr_t * TraceBuffer,size_t Size,void * Context)60 size_t SegvBacktrace(uintptr_t *TraceBuffer, size_t Size, void *Context) {
61 return BacktraceCommon(TraceBuffer, Size, Context);
62 }
63
PrintBacktrace(uintptr_t * Trace,size_t TraceLength,gwp_asan::Printf_t Printf)64 static void PrintBacktrace(uintptr_t *Trace, size_t TraceLength,
65 gwp_asan::Printf_t Printf) {
66 __sanitizer::StackTrace StackTrace;
67 StackTrace.trace = reinterpret_cast<__sanitizer::uptr *>(Trace);
68 StackTrace.size = TraceLength;
69
70 if (StackTrace.size == 0) {
71 Printf(" <unknown (does your allocator support backtracing?)>\n\n");
72 return;
73 }
74
75 __sanitizer::InternalScopedString buffer;
76 StackTrace.PrintTo(&buffer);
77 Printf("%s\n", buffer.data());
78 }
79 } // anonymous namespace
80
81 namespace gwp_asan {
82 namespace backtrace {
83
84 // This function is thread-compatible. It must be synchronised in respect to any
85 // other calls to getBacktraceFunction(), calls to getPrintBacktraceFunction(),
86 // and calls to either of the functions that they return. Furthermore, this may
87 // require synchronisation with any calls to sanitizer_common that use flags.
88 // Generally, this function will be called during the initialisation of the
89 // allocator, which is done in a thread-compatible manner.
getBacktraceFunction()90 options::Backtrace_t getBacktraceFunction() {
91 // The unwinder requires the default flags to be set.
92 __sanitizer::SetCommonFlagsDefaults();
93 __sanitizer::InitializeCommonFlags();
94 return Backtrace;
95 }
96
getPrintBacktraceFunction()97 PrintBacktrace_t getPrintBacktraceFunction() { return PrintBacktrace; }
getSegvBacktraceFunction()98 SegvBacktrace_t getSegvBacktraceFunction() { return SegvBacktrace; }
99
100 } // namespace backtrace
101 } // namespace gwp_asan
102