libunwind/test/unwind_leaffunction.pass.cpp

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// Ensure that leaf function can be unwund.
// REQUIRES: target={{(aarch64|loongarch64|riscv64|s390x|x86_64)-.+}}
// UNSUPPORTED: target={{.*-windows.*}}

// TODO: Figure out why this fails with Memory Sanitizer.
// XFAIL: msan

// Note: this test fails on musl because:
//
//  (a) musl disables emission of unwind information for its build, and
//  (b) musl's signal trampolines don't include unwind information
//
// XFAIL: target={{.*}}-musl

#undef NDEBUG
#include "support/func_bounds.h"
#include <assert.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <unwind.h>

FUNC_BOUNDS_DECL(main_func);

_Unwind_Reason_Code frame_handler(struct _Unwind_Context* ctx, void* arg) {
  (void)arg;

  // Unwind until the main is reached, above frames depend on the platform and
  // architecture.
  uintptr_t ip = _Unwind_GetIP(ctx);
  if (ip >= (uintptr_t)FUNC_START(main_func) &&
      ip < (uintptr_t)FUNC_END(main_func)) {
    _Exit(0);
  }

  return _URC_NO_REASON;
}

void signal_handler(int signum) {
  (void)signum;
  _Unwind_Backtrace(frame_handler, NULL);
  _Exit(-1);
}

__attribute__((noinline)) void crashing_leaf_func(int do_trap) {
  // libunwind searches for the address before the return address which points
  // to the trap instruction. We make the trap conditional and prevent inlining
  // of the function to ensure that the compiler doesn't remove the `ret`
  // instruction altogether.
  //
  // It's also important that the trap instruction isn't the first instruction
  // in the function (which it isn't because of the branch) for other unwinders
  // that also decrement pc.
  if (do_trap)
    __builtin_trap();
}

FUNC_ATTR(main_func) int main(int, char **) {
  signal(SIGTRAP, signal_handler);
  signal(SIGILL, signal_handler);
  crashing_leaf_func(1);
  return -2;
}