diff options
Diffstat (limited to 'lib/libproc/proc_bkpt.c')
| -rw-r--r-- | lib/libproc/proc_bkpt.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/lib/libproc/proc_bkpt.c b/lib/libproc/proc_bkpt.c new file mode 100644 index 000000000000..8649da178bb9 --- /dev/null +++ b/lib/libproc/proc_bkpt.c @@ -0,0 +1,262 @@ +/*- + * SPDX-License-Identifier: BSD-2-Clause + * + * Copyright (c) 2010 The FreeBSD Foundation + * + * 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/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(__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; + 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", (unsigned long)address); + + stopped = 0; + if (phdl->status != PS_STOP) { + if (proc_stop(phdl) != 0) + return (-1); + stopped = 1; + } + + /* + * Read the original instruction. + */ + instr = 0; + piod.piod_op = PIOD_READ_I; + piod.piod_offs = (void *)address; + 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. + */ + instr = BREAKPOINT_INSTR; + piod.piod_op = PIOD_WRITE_I; + piod.piod_offs = (void *)address; + 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; + 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", (unsigned long)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. + */ + instr = saved; + piod.piod_op = PIOD_WRITE_I; + piod.piod_offs = (void *)address; + 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); +} |