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/* Copyright (c) 2013, Scott Tsai
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef DEBUG_BREAK_H
#define DEBUG_BREAK_H
#if defined(_MSC_VER) || defined(__MINGW32__)
#define debug_break __debugbreak
#else
#include <signal.h>
#include <unistd.h>
#include <sys/syscall.h>
#ifdef __cplusplus
extern "C" {
#endif
enum {
/* gcc optimizers consider code after __builtin_trap() dead.
* Making __builtin_trap() unsuitable for breaking into the debugger */
DEBUG_BREAK_PREFER_BUILTIN_TRAP_TO_SIGTRAP = 0,
};
#if defined(__i386__) || defined(__x86_64__)
enum { HAVE_TRAP_INSTRUCTION = 1, };
__attribute__((gnu_inline, always_inline))
static void __inline__ trap_instruction(void)
{
__asm__ volatile("int $0x03");
}
#elif defined(__thumb__)
enum { HAVE_TRAP_INSTRUCTION = 1, };
/* FIXME: handle __THUMB_INTERWORK__ */
__attribute__((gnu_inline, always_inline))
static void __inline__ trap_instruction(void)
{
/* See 'arm-linux-tdep.c' in GDB source.
* Both instruction sequences below works. */
#if 1
/* 'eabi_linux_thumb_le_breakpoint' */
__asm__ volatile(".inst 0xde01");
#else
/* 'eabi_linux_thumb2_le_breakpoint' */
__asm__ volatile(".inst.w 0xf7f0a000");
#endif
/* Known problem:
* After a breakpoint hit, can't stepi, step, or continue in GDB.
* 'step' stuck on the same instruction.
*
* Workaround: a new GDB command,
* 'debugbreak-step' is defined in debugbreak-gdb.py
* that does:
* (gdb) set $instruction_len = 2
* (gdb) tbreak *($pc + $instruction_len)
* (gdb) jump *($pc + $instruction_len)
*/
}
#elif defined(__arm__) && !defined(__thumb__)
enum { HAVE_TRAP_INSTRUCTION = 1, };
__attribute__((gnu_inline, always_inline))
static void __inline__ trap_instruction(void)
{
/* See 'arm-linux-tdep.c' in GDB source,
* 'eabi_linux_arm_le_breakpoint' */
__asm__ volatile(".inst 0xe7f001f0");
/* Has same known problem and workaround
* as Thumb mode */
}
#else
enum { HAVE_TRAP_INSTRUCTION = 0, };
#endif
__attribute__((gnu_inline, always_inline))
static void __inline__ debug_break(void)
{
if (HAVE_TRAP_INSTRUCTION) {
#if defined(ETH_EMSCRIPTEN)
asm("debugger");
#else
trap_instruction();
#endif
} else if (DEBUG_BREAK_PREFER_BUILTIN_TRAP_TO_SIGTRAP) {
/* raises SIGILL on Linux x86{,-64}, to continue in gdb:
* (gdb) handle SIGILL stop nopass
* */
__builtin_trap();
} else {
raise(SIGTRAP);
}
}
#ifdef __cplusplus
}
#endif
#endif
#endif
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