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 
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, bp, context, 0, 0, request_fast);
27   }
28   Unwind(max_depth, pc, 0, context, 0, 0, false);
29 }
30 
31 namespace {
32 size_t Backtrace(uintptr_t *TraceBuffer, size_t Size) {
33   __sanitizer::BufferedStackTrace Trace;
34   Trace.Reset();
35   if (Size > __sanitizer::kStackTraceMax)
36     Size = __sanitizer::kStackTraceMax;
37 
38   Trace.Unwind((__sanitizer::uptr)__builtin_return_address(0),
39                (__sanitizer::uptr)__builtin_frame_address(0),
40                /* ucontext */ nullptr,
41                /* fast unwind */ true, Size - 1);
42 
43   memcpy(TraceBuffer, Trace.trace, Trace.size * sizeof(uintptr_t));
44   return Trace.size;
45 }
46 
47 static void PrintBacktrace(uintptr_t *Trace, size_t TraceLength,
48                            gwp_asan::options::Printf_t Printf) {
49   __sanitizer::StackTrace StackTrace;
50   StackTrace.trace = reinterpret_cast<__sanitizer::uptr *>(Trace);
51   StackTrace.size = TraceLength;
52 
53   if (StackTrace.size == 0) {
54     Printf("  <unknown (does your allocator support backtracing?)>\n\n");
55     return;
56   }
57 
58   StackTrace.Print();
59 }
60 } // anonymous namespace
61 
62 namespace gwp_asan {
63 namespace options {
64 // This function is thread-compatible. It must be synchronised in respect to any
65 // other calls to getBacktraceFunction(), calls to getPrintBacktraceFunction(),
66 // and calls to either of the functions that they return. Furthermore, this may
67 // require synchronisation with any calls to sanitizer_common that use flags.
68 // Generally, this function will be called during the initialisation of the
69 // allocator, which is done in a thread-compatible manner.
70 Backtrace_t getBacktraceFunction() {
71   // The unwinder requires the default flags to be set.
72   __sanitizer::SetCommonFlagsDefaults();
73   __sanitizer::InitializeCommonFlags();
74   return Backtrace;
75 }
76 PrintBacktrace_t getPrintBacktraceFunction() { return PrintBacktrace; }
77 } // namespace options
78 } // namespace gwp_asan
79