libunwind/test/unwind_leaffunction.pass.cpp

   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 // Note: this test fails on musl because:
  17 //
  18 //  (a) musl disables emission of unwind information for its build, and
  19 //  (b) musl's signal trampolines don't include unwind information
  20 //
  21 // XFAIL: target={{.*}}-musl
  22
  23 #undef NDEBUG
  24 #include <assert.h>
  25 #include <signal.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <sys/types.h>
  30 #include <unistd.h>
  31 #include <unwind.h>
  32
  33 // Using __attribute__((section("main_func"))) is ELF specific, but then
  34 // this entire test is marked as requiring Linux, so we should be good.
  35 //
  36 // We don't use dladdr() because on musl it's a no-op when statically linked.
  37 extern char __start_main_func;
  38 extern char __stop_main_func;
  39
  40 _Unwind_Reason_Code frame_handler(struct _Unwind_Context* ctx, void* arg) {
  41   (void)arg;
  42
  43   // Unwind until the main is reached, above frames depend on the platform and
  44   // architecture.
  45   uintptr_t ip = _Unwind_GetIP(ctx);
  46   if (ip >= (uintptr_t)&__start_main_func &&
  47       ip < (uintptr_t)&__stop_main_func) {
  48     _Exit(0);
  49   }
  50
  51   return _URC_NO_REASON;
  52 }
  53
  54 void signal_handler(int signum) {
  55   (void)signum;
  56   _Unwind_Backtrace(frame_handler, NULL);
  57   _Exit(-1);
  58 }
  59
  60 __attribute__((noinline)) void crashing_leaf_func(int do_trap) {
  61   // libunwind searches for the address before the return address which points
  62   // to the trap instruction. We make the trap conditional and prevent inlining
  63   // of the function to ensure that the compiler doesn't remove the `ret`
  64   // instruction altogether.
  65   //
  66   // It's also important that the trap instruction isn't the first instruction
  67   // in the function (which it isn't because of the branch) for other unwinders
  68   // that also decrement pc.
  69   if (do_trap)
  70     __builtin_trap();
  71 }
  72
  73 __attribute__((section("main_func"))) int main(int, char **) {
  74   signal(SIGTRAP, signal_handler);
  75   signal(SIGILL, signal_handler);
  76   crashing_leaf_func(1);
  77   return -2;
  78 }