1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10// Ensure that leaf function can be unwund.
11// REQUIRES: target={{(aarch64|riscv64|s390x|x86_64)-.+linux.*}}
12
13// TODO: Figure out why this fails with Memory Sanitizer.
14// XFAIL: msan
15
16#undef NDEBUG
17#include <assert.h>
18#include <dlfcn.h>
19#include <signal.h>
20#include <stdio.h>
21#include <stdlib.h>
22#include <string.h>
23#include <sys/types.h>
24#include <unistd.h>
25#include <unwind.h>
26
27_Unwind_Reason_Code frame_handler(struct _Unwind_Context* ctx, void* arg) {
28 (void)arg;
29 Dl_info info = { .dli_fname: 0, .dli_fbase: 0, .dli_sname: 0, .dli_saddr: 0 };
30
31 // Unwind until the main is reached, above frames depend on the platform and
32 // architecture.
33 if (dladdr(address: reinterpret_cast<void *>(_Unwind_GetIP(ctx)), info: &info) &&
34 info.dli_sname && !strcmp(s1: "main", s2: info.dli_sname)) {
35 _Exit(status: 0);
36 }
37 return _URC_NO_REASON;
38}
39
40void signal_handler(int signum) {
41 (void)signum;
42 _Unwind_Backtrace(frame_handler, NULL);
43 _Exit(status: -1);
44}
45
46__attribute__((noinline)) void crashing_leaf_func(int do_trap) {
47 // libunwind searches for the address before the return address which points
48 // to the trap instruction. We make the trap conditional and prevent inlining
49 // of the function to ensure that the compiler doesn't remove the `ret`
50 // instruction altogether.
51 //
52 // It's also important that the trap instruction isn't the first instruction
53 // in the function (which it isn't because of the branch) for other unwinders
54 // that also decrement pc.
55 if (do_trap)
56 __builtin_trap();
57}
58
59int main(int, char**) {
60 signal(SIGTRAP, handler: signal_handler);
61 signal(SIGILL, handler: signal_handler);
62 crashing_leaf_func(do_trap: 1);
63 return -2;
64}
65

source code of libunwind/test/unwind_leaffunction.pass.cpp