/* * 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 #ifdef __FBSDID __FBSDID("$FreeBSD: head/lib/libproc/proc_bkpt.c 287106 2015-08-24 12:17:15Z andrew $"); #else __RCSID("$NetBSD: proc_bkpt.c,v 1.6 2018/07/20 20:50:34 christos Exp $"); #endif #include #include #include #include #include #include #include #include #include #include #include "_libproc.h" #ifndef PTRACE_BREAKPOINT #error "Add support for your architecture" #endif 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, proc_breakpoint_t *saved) { struct ptrace_io_desc piod; unsigned long paddr, caddr; int ret = 0, stopped; proc_breakpoint_t copy; if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || phdl->status == PS_IDLE) { errno = ENOENT; return (-1); } DPRINTFX("adding breakpoint at 0x%" PRIxPTR, address); stopped = 0; if (phdl->status != PS_STOP) { if (proc_stop(phdl) != 0) return (-1); stopped = 1; } /* * Read the original instruction. */ caddr = address; paddr = 0; piod.piod_op = PIOD_READ_I; piod.piod_offs = (void *)caddr; piod.piod_addr = (void *)saved->data; piod.piod_len = sizeof(saved->data); if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) { DPRINTF("ERROR: couldn't read instruction at address 0x%" PRIxPTR, address); ret = -1; goto done; } /* * Write a breakpoint instruction to that address. */ caddr = address; piod.piod_op = PIOD_WRITE_I; piod.piod_offs = (void *)caddr; piod.piod_addr = (void *)PTRACE_BREAKPOINT; piod.piod_len = sizeof(PTRACE_BREAKPOINT); if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) { DPRINTF("ERROR: couldn't write instruction at address 0x%" PRIxPTR, 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, proc_breakpoint_t *saved) { struct ptrace_io_desc piod; unsigned long paddr, caddr; int ret = 0, stopped; if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || phdl->status == PS_IDLE) { errno = ENOENT; return (-1); } DPRINTFX("removing breakpoint at 0x%" PRIxPTR, 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; piod.piod_op = PIOD_WRITE_I; piod.piod_offs = (void *)caddr; piod.piod_addr = (void *)saved->data; piod.piod_len = sizeof(saved->data); if (ptrace(PT_IO, proc_getpid(phdl), &piod, 0) < 0) { DPRINTF("ERROR: couldn't write instruction at address 0x%" PRIxPTR, 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 instruction 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 PTRACE_BREAKPOINT_ADJ *pc = *pc - PTRACE_BREAKPOINT_ADJ; #endif } /* * Step over the breakpoint. */ int proc_bkptexec(struct proc_handle *phdl, proc_breakpoint_t *saved) { unsigned long pc; proc_breakpoint_t 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); #ifdef PT_STEP if (ptrace(PT_STEP, proc_getpid(phdl), (void *)(intptr_t)1, 0) < 0) { DPRINTFX("ERROR: ptrace step failed"); return (-1); } #endif 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(memcmp(saved, &samesaved, sizeof(samesaved)) == 0); return (0); }