813b26945c
process if it has not already been stopped, since this is required for ptrace(2) to work. libdtrace does not seem to stop target processes before trying to remove their breakpoints, so we were previously failing to remove the breakpoint on r_debug_state() in rtld. This was causing processes to die with SIGTRAP if they called dlopen(3) after dtrace(1) had detached. Reported by: symbolics@gmx.com Reviewed by: rpaulo MFC after: 1 month
243 lines
6.1 KiB
C
243 lines
6.1 KiB
C
/*
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* Copyright (c) 2010 The FreeBSD Foundation
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* All rights reserved.
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*
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* This software was developed by Rui Paulo under sponsorship from the
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* FreeBSD Foundation.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/ptrace.h>
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#include <sys/wait.h>
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#include <machine/_inttypes.h>
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#include <assert.h>
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#include <err.h>
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#include <errno.h>
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#include <signal.h>
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#include <stdio.h>
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#include "_libproc.h"
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#if defined(__i386__) || defined(__amd64__)
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#define BREAKPOINT_INSTR 0xcc /* int 0x3 */
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#define BREAKPOINT_INSTR_SZ 1
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#elif defined(__mips__)
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#define BREAKPOINT_INSTR 0xd /* break */
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#define BREAKPOINT_INSTR_SZ 4
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#elif defined(__powerpc__)
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#define BREAKPOINT_INSTR 0x7fe00008 /* trap */
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#define BREAKPOINT_INSTR_SZ 4
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#else
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#error "Add support for your architecture"
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#endif
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static void
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proc_cont(struct proc_handle *phdl)
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{
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ptrace(PT_CONTINUE, proc_getpid(phdl), (caddr_t)1, 0);
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}
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static int
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proc_stop(struct proc_handle *phdl)
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{
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int status;
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if (kill(proc_getpid(phdl), SIGSTOP) == -1) {
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DPRINTF("kill %d", proc_getpid(phdl));
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return (-1);
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} else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) {
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DPRINTF("waitpid %d", proc_getpid(phdl));
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return (-1);
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} else if (!WIFSTOPPED(status)) {
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DPRINTFX("waitpid: unexpected status 0x%x", status);
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return (-1);
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}
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return (0);
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}
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int
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proc_bkptset(struct proc_handle *phdl, uintptr_t address,
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unsigned long *saved)
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{
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struct ptrace_io_desc piod;
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unsigned long paddr, caddr;
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int ret = 0;
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*saved = 0;
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if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
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phdl->status == PS_IDLE) {
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errno = ENOENT;
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return (-1);
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}
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DPRINTFX("adding breakpoint at 0x%lx", address);
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if (phdl->status != PS_STOP)
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if (proc_stop(phdl) != 0)
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return (-1);
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/*
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* Read the original instruction.
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*/
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caddr = address;
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paddr = 0;
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piod.piod_op = PIOD_READ_I;
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piod.piod_offs = (void *)caddr;
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piod.piod_addr = &paddr;
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piod.piod_len = BREAKPOINT_INSTR_SZ;
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if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
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DPRINTF("ERROR: couldn't read instruction at address 0x%"
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PRIuPTR, address);
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ret = -1;
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goto done;
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}
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*saved = paddr;
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/*
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* Write a breakpoint instruction to that address.
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*/
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caddr = address;
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paddr = BREAKPOINT_INSTR;
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piod.piod_op = PIOD_WRITE_I;
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piod.piod_offs = (void *)caddr;
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piod.piod_addr = &paddr;
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piod.piod_len = BREAKPOINT_INSTR_SZ;
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if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
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DPRINTF("ERROR: couldn't write instruction at address 0x%"
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PRIuPTR, address);
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ret = -1;
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goto done;
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}
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done:
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if (phdl->status != PS_STOP)
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/* Restart the process if we had to stop it. */
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proc_cont(phdl);
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return (ret);
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}
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int
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proc_bkptdel(struct proc_handle *phdl, uintptr_t address,
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unsigned long saved)
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{
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struct ptrace_io_desc piod;
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unsigned long paddr, caddr;
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int ret = 0;
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if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD ||
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phdl->status == PS_IDLE) {
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errno = ENOENT;
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return (-1);
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}
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DPRINTFX("removing breakpoint at 0x%lx", address);
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if (phdl->status != PS_STOP)
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if (proc_stop(phdl) != 0)
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return (-1);
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/*
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* Overwrite the breakpoint instruction that we setup previously.
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*/
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caddr = address;
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paddr = saved;
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piod.piod_op = PIOD_WRITE_I;
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piod.piod_offs = (void *)caddr;
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piod.piod_addr = &paddr;
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piod.piod_len = BREAKPOINT_INSTR_SZ;
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if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) {
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DPRINTF("ERROR: couldn't write instruction at address 0x%"
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PRIuPTR, address);
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ret = -1;
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}
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if (phdl->status != PS_STOP)
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/* Restart the process if we had to stop it. */
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proc_cont(phdl);
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return (ret);
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}
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/*
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* Decrement pc so that we delete the breakpoint at the correct
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* address, i.e. at the BREAKPOINT_INSTR address.
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*/
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void
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proc_bkptregadj(unsigned long *pc)
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{
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*pc = *pc - BREAKPOINT_INSTR_SZ;
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}
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/*
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* Step over the breakpoint.
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*/
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int
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proc_bkptexec(struct proc_handle *phdl, unsigned long saved)
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{
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unsigned long pc;
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unsigned long samesaved;
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int status;
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if (proc_regget(phdl, REG_PC, &pc) < 0) {
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DPRINTFX("ERROR: couldn't get PC register");
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return (-1);
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}
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proc_bkptregadj(&pc);
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if (proc_bkptdel(phdl, pc, saved) < 0) {
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DPRINTFX("ERROR: couldn't delete breakpoint");
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return (-1);
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}
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/*
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* Go back in time and step over the new instruction just
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* set up by proc_bkptdel().
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*/
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proc_regset(phdl, REG_PC, pc);
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if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) {
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DPRINTFX("ERROR: ptrace step failed");
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return (-1);
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}
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proc_wstatus(phdl);
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status = proc_getwstat(phdl);
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if (!WIFSTOPPED(status)) {
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DPRINTFX("ERROR: don't know why process stopped");
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return (-1);
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}
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/*
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* Restore the breakpoint. The saved instruction should be
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* the same as the one that we were passed in.
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*/
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if (proc_bkptset(phdl, pc, &samesaved) < 0) {
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DPRINTFX("ERROR: couldn't restore breakpoint");
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return (-1);
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}
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assert(samesaved == saved);
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return (0);
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}
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