freebsd-dev/lib/libproc/proc_bkpt.c
Pedro F. Giffuni 5e53a4f90f lib: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-26 02:00:33 +00:00

275 lines
7.0 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2010 The FreeBSD Foundation
* All rights reserved.
*
* This software was developed by Rui Paulo under sponsorship from the
* FreeBSD Foundation.
*
* 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 AUTHOR 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 AUTHOR 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/types.h>
#include <sys/ptrace.h>
#include <sys/wait.h>
#include <assert.h>
#include <err.h>
#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include "_libproc.h"
#if defined(__aarch64__)
#define AARCH64_BRK 0xd4200000
#define AARCH64_BRK_IMM16_SHIFT 5
#define AARCH64_BRK_IMM16_VAL (0xd << AARCH64_BRK_IMM16_SHIFT)
#define BREAKPOINT_INSTR (AARCH64_BRK | AARCH64_BRK_IMM16_VAL)
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__amd64__) || defined(__i386__)
#define BREAKPOINT_INSTR 0xcc /* int 0x3 */
#define BREAKPOINT_INSTR_SZ 1
#define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ
#elif defined(__arm__)
#define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__mips__)
#define BREAKPOINT_INSTR 0xd /* break */
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__powerpc__)
#define BREAKPOINT_INSTR 0x7fe00008 /* trap */
#define BREAKPOINT_INSTR_SZ 4
#elif defined(__riscv)
#define BREAKPOINT_INSTR 0x00100073 /* sbreak */
#define BREAKPOINT_INSTR_SZ 4
#else
#error "Add support for your architecture"
#endif
/*
* Use 4-bytes holder for breakpoint instruction on all the platforms.
* Works for x86 as well until it is endian-little platform.
* (We are coping one byte only on x86 from this 4-bytes piece of
* memory).
*/
typedef uint32_t instr_t;
static int
proc_stop(struct proc_handle *phdl)
{
int status;
if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
DPRINTF("kill %d", proc_getpid(phdl));
return (-1);
} else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
DPRINTF("waitpid %d", proc_getpid(phdl));
return (-1);
} else if (!WIFSTOPPED(status)) {
DPRINTFX("waitpid: unexpected status 0x%x", status);
return (-1);
}
return (0);
}
int
proc_bkptset(struct proc_handle *phdl, uintptr_t address,
unsigned long *saved)
{
struct ptrace_io_desc piod;
unsigned long caddr;
int ret = 0, stopped;
instr_t instr;
*saved = 0;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("adding breakpoint at 0x%lx", address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Read the original instruction.
*/
caddr = address;
instr = 0;
piod.piod_op = PIOD_READ_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't read instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
goto done;
}
*saved = instr;
/*
* Write a breakpoint instruction to that address.
*/
caddr = address;
instr = BREAKPOINT_INSTR;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
goto done;
}
done:
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
int
proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
unsigned long saved)
{
struct ptrace_io_desc piod;
unsigned long caddr;
int ret = 0, stopped;
instr_t instr;
if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
phdl->status == PS_IDLE) {
errno = ENOENT;
return (-1);
}
DPRINTFX("removing breakpoint at 0x%lx", address);
stopped = 0;
if (phdl->status != PS_STOP) {
if (proc_stop(phdl) != 0)
return (-1);
stopped = 1;
}
/*
* Overwrite the breakpoint instruction that we setup previously.
*/
caddr = address;
instr = saved;
piod.piod_op = PIOD_WRITE_I;
piod.piod_offs = (void *)caddr;
piod.piod_addr = &instr;
piod.piod_len = BREAKPOINT_INSTR_SZ;
if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
DPRINTF("ERROR: couldn't write instruction at address 0x%jx",
(uintmax_t)address);
ret = -1;
}
if (stopped)
/* Restart the process if we had to stop it. */
proc_continue(phdl);
return (ret);
}
/*
* Decrement pc so that we delete the breakpoint at the correct
* address, i.e. at the BREAKPOINT_INSTR address.
*
* This is only needed on some architectures where the pc value
* when reading registers points at the instruction after the
* breakpoint, e.g. x86.
*/
void
proc_bkptregadj(unsigned long *pc)
{
(void)pc;
#ifdef BREAKPOINT_ADJUST_SZ
*pc = *pc - BREAKPOINT_ADJUST_SZ;
#endif
}
/*
* Step over the breakpoint.
*/
int
proc_bkptexec(struct proc_handle *phdl, unsigned long saved)
{
unsigned long pc;
unsigned long samesaved;
int status;
if (proc_regget(phdl, REG_PC, &pc) < 0) {
DPRINTFX("ERROR: couldn't get PC register");
return (-1);
}
proc_bkptregadj(&pc);
if (proc_bkptdel(phdl, pc, saved) < 0) {
DPRINTFX("ERROR: couldn't delete breakpoint");
return (-1);
}
/*
* Go back in time and step over the new instruction just
* set up by proc_bkptdel().
*/
proc_regset(phdl, REG_PC, pc);
if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) {
DPRINTFX("ERROR: ptrace step failed");
return (-1);
}
proc_wstatus(phdl);
status = proc_getwstat(phdl);
if (!WIFSTOPPED(status)) {
DPRINTFX("ERROR: don't know why process stopped");
return (-1);
}
/*
* Restore the breakpoint. The saved instruction should be
* the same as the one that we were passed in.
*/
if (proc_bkptset(phdl, pc, &samesaved) < 0) {
DPRINTFX("ERROR: couldn't restore breakpoint");
return (-1);
}
assert(samesaved == saved);
return (0);
}