llvm-capstone/libunwind/test/unwind_leaffunction.pass.cpp
Leonard Chan f178a05f22 [libunwind] Fix unwind_leaffunction test
It's possible for this test not to pass if the libc used does not provide
unwind info for raise. We can replace it with __builtin_cast, which can lead
to a SIGTRAP on x86_64 and a SIGILL on aarch64.

Using this alternative, a nop is needed before the __builtin_cast. This is
because libunwind incorrectly decrements pc, which can cause pc to jump into
the previous function and use the incorrect FDE.

Differential Revision: https://reviews.llvm.org/D114818
2021-12-03 11:21:20 -08:00

56 lines
1.7 KiB
C++

// -*- 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: linux && (target={{aarch64-.+}} || target={{x86_64-.+}})
#include <assert.h>
#include <dlfcn.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <unwind.h>
_Unwind_Reason_Code frame_handler(struct _Unwind_Context* ctx, void* arg) {
(void)arg;
Dl_info info = { 0, 0, 0, 0 };
// Unwind util the main is reached, above frames deeped on the platfrom and architecture.
if (dladdr(reinterpret_cast<void *>(_Unwind_GetIP(ctx)), &info) &&
info.dli_sname && !strcmp("main", info.dli_sname)) {
_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(void) {
// libunwind searches for the address before the return address which points
// to the trap instruction. NOP guarantees the trap instruction is not the
// first instruction of the function.
// We should keep this here for other unwinders that also decrement pc.
__asm__ __volatile__("nop");
__builtin_trap();
}
int main(int, char**) {
signal(SIGTRAP, signal_handler);
signal(SIGILL, signal_handler);
crashing_leaf_func();
return -2;
}