bin/debug_agent/zxdb_test_app.cc

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include <zircon/syscalls.h>

// This is a simple app for testing various aspects of the debugger. To build,
// set include_test_app to true in the BUILD.gn file in this directory.

// The binary will end up in /system/test/zxdb_test_app.

void DebugBreak() {
#if defined(__x86_64__)
  __asm__ volatile("int3");
#elif defined(__aarch64__)
  __asm__ volatile("brk 0");
#else
#error
#endif
}

// This function is helpful to test handling of duplicate functions on the
// stack for e.g. "finish".
__attribute__ ((noinline)) void RecursiveCall(int times) {
  if (times > 0)
    RecursiveCall(times - 1);
  zx_debug_write("hello\n", 6);  // Prevent tail recursion optimizations.
}

void PrintHello() {
  const char msg[] = "Hello from zxdb_test_app!\n";
  zx_debug_write(msg, strlen(msg));

  // This code is here to test disassembly of FP instructions.
  volatile float a = 3.14159265358979;
  volatile float b = 2.71828182845904;
  volatile float c = a * b;
  (void)c;  // Prevent unused variable warning.
}

int main(int argc, char* argv[]) {
  // Print out the address of main to the system debug log.
  char buf[128];
  snprintf(buf, sizeof(buf), "zxdb_test_app, &PrintHello = 0x%llx\n",
           static_cast<unsigned long long>(
               reinterpret_cast<uintptr_t>(&PrintHello)));
  zx_debug_write(buf, strlen(buf));

  DebugBreak();
  PrintHello();
  RecursiveCall(3);
  return 0;
}