proc_bkpt.c revision 259969
1/* 2 * Copyright (c) 2010 The FreeBSD Foundation 3 * All rights reserved. 4 * 5 * This software was developed by Rui Paulo under sponsorship from the 6 * FreeBSD Foundation. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30#include <sys/cdefs.h> 31__FBSDID("$FreeBSD: stable/10/lib/libproc/proc_bkpt.c 259969 2013-12-27 22:30:36Z markj $"); 32 33#include <sys/types.h> 34#include <sys/ptrace.h> 35#include <sys/wait.h> 36#include <machine/_inttypes.h> 37 38#include <assert.h> 39#include <err.h> 40#include <errno.h> 41#include <signal.h> 42#include <stdio.h> 43#include "_libproc.h" 44 45#if defined(__i386__) || defined(__amd64__) 46#define BREAKPOINT_INSTR 0xcc /* int 0x3 */ 47#define BREAKPOINT_INSTR_SZ 1 48#elif defined(__mips__) 49#define BREAKPOINT_INSTR 0xd /* break */ 50#define BREAKPOINT_INSTR_SZ 4 51#elif defined(__powerpc__) 52#define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 53#define BREAKPOINT_INSTR_SZ 4 54#else 55#error "Add support for your architecture" 56#endif 57 58static void 59proc_cont(struct proc_handle *phdl) 60{ 61 62 ptrace(PT_CONTINUE, proc_getpid(phdl), (caddr_t)1, 0); 63} 64 65static int 66proc_stop(struct proc_handle *phdl) 67{ 68 int status; 69 70 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 71 DPRINTF("kill %d", proc_getpid(phdl)); 72 return (-1); 73 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 74 DPRINTF("waitpid %d", proc_getpid(phdl)); 75 return (-1); 76 } else if (!WIFSTOPPED(status)) { 77 DPRINTFX("waitpid: unexpected status 0x%x", status); 78 return (-1); 79 } 80 81 return (0); 82} 83 84int 85proc_bkptset(struct proc_handle *phdl, uintptr_t address, 86 unsigned long *saved) 87{ 88 struct ptrace_io_desc piod; 89 unsigned long paddr, caddr; 90 int ret = 0; 91 92 *saved = 0; 93 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 94 phdl->status == PS_IDLE) { 95 errno = ENOENT; 96 return (-1); 97 } 98 99 DPRINTFX("adding breakpoint at 0x%lx", address); 100 101 if (phdl->status != PS_STOP) 102 if (proc_stop(phdl) != 0) 103 return (-1); 104 105 /* 106 * Read the original instruction. 107 */ 108 caddr = address; 109 paddr = 0; 110 piod.piod_op = PIOD_READ_I; 111 piod.piod_offs = (void *)caddr; 112 piod.piod_addr = &paddr; 113 piod.piod_len = BREAKPOINT_INSTR_SZ; 114 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 115 DPRINTF("ERROR: couldn't read instruction at address 0x%" 116 PRIuPTR, address); 117 ret = -1; 118 goto done; 119 } 120 *saved = paddr; 121 /* 122 * Write a breakpoint instruction to that address. 123 */ 124 caddr = address; 125 paddr = BREAKPOINT_INSTR; 126 piod.piod_op = PIOD_WRITE_I; 127 piod.piod_offs = (void *)caddr; 128 piod.piod_addr = &paddr; 129 piod.piod_len = BREAKPOINT_INSTR_SZ; 130 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 131 DPRINTF("ERROR: couldn't write instruction at address 0x%" 132 PRIuPTR, address); 133 ret = -1; 134 goto done; 135 } 136 137done: 138 if (phdl->status != PS_STOP) 139 /* Restart the process if we had to stop it. */ 140 proc_cont(phdl); 141 142 return (ret); 143} 144 145int 146proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 147 unsigned long saved) 148{ 149 struct ptrace_io_desc piod; 150 unsigned long paddr, caddr; 151 int ret = 0; 152 153 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 154 phdl->status == PS_IDLE) { 155 errno = ENOENT; 156 return (-1); 157 } 158 159 DPRINTFX("removing breakpoint at 0x%lx", address); 160 161 if (phdl->status != PS_STOP) 162 if (proc_stop(phdl) != 0) 163 return (-1); 164 165 /* 166 * Overwrite the breakpoint instruction that we setup previously. 167 */ 168 caddr = address; 169 paddr = saved; 170 piod.piod_op = PIOD_WRITE_I; 171 piod.piod_offs = (void *)caddr; 172 piod.piod_addr = &paddr; 173 piod.piod_len = BREAKPOINT_INSTR_SZ; 174 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 175 DPRINTF("ERROR: couldn't write instruction at address 0x%" 176 PRIuPTR, address); 177 ret = -1; 178 } 179 180 if (phdl->status != PS_STOP) 181 /* Restart the process if we had to stop it. */ 182 proc_cont(phdl); 183 184 return (ret); 185} 186 187/* 188 * Decrement pc so that we delete the breakpoint at the correct 189 * address, i.e. at the BREAKPOINT_INSTR address. 190 */ 191void 192proc_bkptregadj(unsigned long *pc) 193{ 194 *pc = *pc - BREAKPOINT_INSTR_SZ; 195} 196 197/* 198 * Step over the breakpoint. 199 */ 200int 201proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 202{ 203 unsigned long pc; 204 unsigned long samesaved; 205 int status; 206 207 if (proc_regget(phdl, REG_PC, &pc) < 0) { 208 DPRINTFX("ERROR: couldn't get PC register"); 209 return (-1); 210 } 211 proc_bkptregadj(&pc); 212 if (proc_bkptdel(phdl, pc, saved) < 0) { 213 DPRINTFX("ERROR: couldn't delete breakpoint"); 214 return (-1); 215 } 216 /* 217 * Go back in time and step over the new instruction just 218 * set up by proc_bkptdel(). 219 */ 220 proc_regset(phdl, REG_PC, pc); 221 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 222 DPRINTFX("ERROR: ptrace step failed"); 223 return (-1); 224 } 225 proc_wstatus(phdl); 226 status = proc_getwstat(phdl); 227 if (!WIFSTOPPED(status)) { 228 DPRINTFX("ERROR: don't know why process stopped"); 229 return (-1); 230 } 231 /* 232 * Restore the breakpoint. The saved instruction should be 233 * the same as the one that we were passed in. 234 */ 235 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 236 DPRINTFX("ERROR: couldn't restore breakpoint"); 237 return (-1); 238 } 239 assert(samesaved == saved); 240 241 return (0); 242} 243