1 //===-- backtrace.h ---------------------------------------------*- 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 #ifndef GWP_ASAN_OPTIONAL_BACKTRACE_H_
10 #define GWP_ASAN_OPTIONAL_BACKTRACE_H_
11 
12 #include "gwp_asan/optional/printf.h"
13 #include "gwp_asan/options.h"
14 
15 namespace gwp_asan {
16 namespace backtrace {
17 // ================================ Description ================================
18 // This function shall take the backtrace provided in `TraceBuffer`, and print
19 // it in a human-readable format using `Print`. Generally, this function shall
20 // resolve raw pointers to section offsets and print them with the following
21 // sanitizer-common format:
22 //      "  #{frame_number} {pointer} in {function name} ({binary name}+{offset}"
23 // e.g. "  #5 0x420459 in _start (/tmp/uaf+0x420459)"
24 // This format allows the backtrace to be symbolized offline successfully using
25 // llvm-symbolizer.
26 // =================================== Notes ===================================
27 // This function may directly or indirectly call malloc(), as the
28 // GuardedPoolAllocator contains a reentrancy barrier to prevent infinite
29 // recursion. Any allocation made inside this function will be served by the
30 // supporting allocator, and will not have GWP-ASan protections.
31 typedef void (*PrintBacktrace_t)(uintptr_t *TraceBuffer, size_t TraceLength,
32                                  Printf_t Print);
33 
34 // Returns a function pointer to a backtrace function that's suitable for
35 // unwinding through a signal handler. This is important primarily for frame-
36 // pointer based unwinders, DWARF or other unwinders can simply provide the
37 // normal backtrace function as the implementation here. On POSIX, SignalContext
38 // should be the `ucontext_t` from the signal handler.
39 typedef size_t (*SegvBacktrace_t)(uintptr_t *TraceBuffer, size_t Size,
40                                   void *SignalContext);
41 
42 // Returns platform-specific provided implementations of Backtrace_t for use
43 // inside the GWP-ASan core allocator.
44 options::Backtrace_t getBacktraceFunction();
45 
46 // Returns platform-specific provided implementations of PrintBacktrace_t and
47 // SegvBacktrace_t for use in the optional SEGV handler.
48 PrintBacktrace_t getPrintBacktraceFunction();
49 SegvBacktrace_t getSegvBacktraceFunction();
50 } // namespace backtrace
51 } // namespace gwp_asan
52 
53 #endif // GWP_ASAN_OPTIONAL_BACKTRACE_H_
54