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("$FreeBSD$"); 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 58 static int 59 proc_stop(struct proc_handle *phdl) 60 { 61 int status; 62 63 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 64 DPRINTF("kill %d", proc_getpid(phdl)); 65 return (-1); 66 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 67 DPRINTF("waitpid %d", proc_getpid(phdl)); 68 return (-1); 69 } else if (!WIFSTOPPED(status)) { 70 DPRINTFX("waitpid: unexpected status 0x%x", status); 71 return (-1); 72 } 73 74 return (0); 75 } 76 77 int 78 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 79 unsigned long *saved) 80 { 81 struct ptrace_io_desc piod; 82 unsigned long paddr, caddr; 83 int ret = 0, stopped; 84 85 *saved = 0; 86 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 87 phdl->status == PS_IDLE) { 88 errno = ENOENT; 89 return (-1); 90 } 91 92 DPRINTFX("adding breakpoint at 0x%lx", address); 93 94 stopped = 0; 95 if (phdl->status != PS_STOP) { 96 if (proc_stop(phdl) != 0) 97 return (-1); 98 stopped = 1; 99 } 100 101 /* 102 * Read the original instruction. 103 */ 104 caddr = address; 105 paddr = 0; 106 piod.piod_op = PIOD_READ_I; 107 piod.piod_offs = (void *)caddr; 108 piod.piod_addr = &paddr; 109 piod.piod_len = BREAKPOINT_INSTR_SZ; 110 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 111 DPRINTF("ERROR: couldn't read instruction at address 0x%" 112 PRIuPTR, address); 113 ret = -1; 114 goto done; 115 } 116 *saved = paddr; 117 /* 118 * Write a breakpoint instruction to that address. 119 */ 120 caddr = address; 121 paddr = BREAKPOINT_INSTR; 122 piod.piod_op = PIOD_WRITE_I; 123 piod.piod_offs = (void *)caddr; 124 piod.piod_addr = &paddr; 125 piod.piod_len = BREAKPOINT_INSTR_SZ; 126 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 127 DPRINTF("ERROR: couldn't write instruction at address 0x%" 128 PRIuPTR, address); 129 ret = -1; 130 goto done; 131 } 132 133 done: 134 if (stopped) 135 /* Restart the process if we had to stop it. */ 136 proc_continue(phdl); 137 138 return (ret); 139 } 140 141 int 142 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 143 unsigned long saved) 144 { 145 struct ptrace_io_desc piod; 146 unsigned long paddr, caddr; 147 int ret = 0, stopped; 148 149 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 150 phdl->status == PS_IDLE) { 151 errno = ENOENT; 152 return (-1); 153 } 154 155 DPRINTFX("removing breakpoint at 0x%lx", address); 156 157 stopped = 0; 158 if (phdl->status != PS_STOP) { 159 if (proc_stop(phdl) != 0) 160 return (-1); 161 stopped = 1; 162 } 163 164 /* 165 * Overwrite the breakpoint instruction that we setup previously. 166 */ 167 caddr = address; 168 paddr = saved; 169 piod.piod_op = PIOD_WRITE_I; 170 piod.piod_offs = (void *)caddr; 171 piod.piod_addr = &paddr; 172 piod.piod_len = BREAKPOINT_INSTR_SZ; 173 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 174 DPRINTF("ERROR: couldn't write instruction at address 0x%" 175 PRIuPTR, address); 176 ret = -1; 177 } 178 179 if (stopped) 180 /* Restart the process if we had to stop it. */ 181 proc_continue(phdl); 182 183 return (ret); 184 } 185 186 /* 187 * Decrement pc so that we delete the breakpoint at the correct 188 * address, i.e. at the BREAKPOINT_INSTR address. 189 */ 190 void 191 proc_bkptregadj(unsigned long *pc) 192 { 193 *pc = *pc - BREAKPOINT_INSTR_SZ; 194 } 195 196 /* 197 * Step over the breakpoint. 198 */ 199 int 200 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 201 { 202 unsigned long pc; 203 unsigned long samesaved; 204 int status; 205 206 if (proc_regget(phdl, REG_PC, &pc) < 0) { 207 DPRINTFX("ERROR: couldn't get PC register"); 208 return (-1); 209 } 210 proc_bkptregadj(&pc); 211 if (proc_bkptdel(phdl, pc, saved) < 0) { 212 DPRINTFX("ERROR: couldn't delete breakpoint"); 213 return (-1); 214 } 215 /* 216 * Go back in time and step over the new instruction just 217 * set up by proc_bkptdel(). 218 */ 219 proc_regset(phdl, REG_PC, pc); 220 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 221 DPRINTFX("ERROR: ptrace step failed"); 222 return (-1); 223 } 224 proc_wstatus(phdl); 225 status = proc_getwstat(phdl); 226 if (!WIFSTOPPED(status)) { 227 DPRINTFX("ERROR: don't know why process stopped"); 228 return (-1); 229 } 230 /* 231 * Restore the breakpoint. The saved instruction should be 232 * the same as the one that we were passed in. 233 */ 234 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 235 DPRINTFX("ERROR: couldn't restore breakpoint"); 236 return (-1); 237 } 238 assert(samesaved == saved); 239 240 return (0); 241 } 242