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: linux && (target={{aarch64-.+}} || target={{x86_64-.+}})
12 
13 #include <assert.h>
14 #include <dlfcn.h>
15 #include <signal.h>
16 #include <stdio.h>
17 #include <stdlib.h>
18 #include <string.h>
19 #include <sys/types.h>
20 #include <unistd.h>
21 #include <unwind.h>
22 
23 _Unwind_Reason_Code frame_handler(struct _Unwind_Context* ctx, void* arg) {
24   (void)arg;
25   Dl_info info = { 0, 0, 0, 0 };
26 
27   // Unwind util the main is reached, above frames deeped on the platfrom and architecture.
28   if (dladdr(reinterpret_cast<void *>(_Unwind_GetIP(ctx)), &info) &&
29       info.dli_sname && !strcmp("main", info.dli_sname)) {
30     _Exit(0);
31   }
32   return _URC_NO_REASON;
33 }
34 
35 void signal_handler(int signum) {
36   (void)signum;
37   _Unwind_Backtrace(frame_handler, NULL);
38   _Exit(-1);
39 }
40 
41 __attribute__((noinline)) void crashing_leaf_func(void) {
42   // libunwind searches for the address before the return address which points
43   // to the trap instruction. NOP guarantees the trap instruction is not the
44   // first instruction of the function.
45   // We should keep this here for other unwinders that also decrement pc.
46   __asm__ __volatile__("nop");
47   __builtin_trap();
48 }
49 
50 int main(int, char**) {
51   signal(SIGTRAP, signal_handler);
52   signal(SIGILL, signal_handler);
53   crashing_leaf_func();
54   return -2;
55 }
56