proc_bkpt.c revision 1.2
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 #ifdef __FBSDID 32 __FBSDID("$FreeBSD: head/lib/libproc/proc_bkpt.c 287106 2015-08-24 12:17:15Z andrew $"); 33 #else 34 __RCSID("$NetBSD: proc_bkpt.c,v 1.2 2015/09/24 14:12:48 christos Exp $"); 35 #endif 36 37 #include <sys/types.h> 38 #include <sys/ptrace.h> 39 #include <sys/wait.h> 40 41 #include <assert.h> 42 #include <err.h> 43 #include <errno.h> 44 #include <inttypes.h> 45 #include <signal.h> 46 #include <stdio.h> 47 #include "_libproc.h" 48 49 #if defined(__aarch64__) 50 #define AARCH64_BRK 0xd4200000 51 #define AARCH64_BRK_IMM16_SHIFT 5 52 #define AARCH64_BRK_IMM16_VAL (0xd << AARCH64_BRK_IMM16_SHIFT) 53 #define BREAKPOINT_INSTR (AARCH64_BRK | AARCH64_BRK_IMM16_VAL) 54 #define BREAKPOINT_INSTR_SZ 4 55 #elif defined(__amd64__) || defined(__i386__) 56 #define BREAKPOINT_INSTR 0xcc /* int 0x3 */ 57 #define BREAKPOINT_INSTR_SZ 1 58 #define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ 59 #elif defined(__arm__) 60 #define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */ 61 #define BREAKPOINT_INSTR_SZ 4 62 #elif defined(__mips__) 63 #define BREAKPOINT_INSTR 0xd /* break */ 64 #define BREAKPOINT_INSTR_SZ 4 65 #elif defined(__powerpc__) 66 #define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 67 #define BREAKPOINT_INSTR_SZ 4 68 #else 69 #error "Add support for your architecture" 70 #endif 71 72 static int 73 proc_stop(struct proc_handle *phdl) 74 { 75 int status; 76 77 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 78 DPRINTF("kill %d", proc_getpid(phdl)); 79 return (-1); 80 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 81 DPRINTF("waitpid %d", proc_getpid(phdl)); 82 return (-1); 83 } else if (!WIFSTOPPED(status)) { 84 DPRINTFX("waitpid: unexpected status 0x%x", status); 85 return (-1); 86 } 87 88 return (0); 89 } 90 91 int 92 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 93 unsigned long *saved) 94 { 95 struct ptrace_io_desc piod; 96 unsigned long paddr, caddr; 97 int ret = 0, stopped; 98 99 *saved = 0; 100 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 101 phdl->status == PS_IDLE) { 102 errno = ENOENT; 103 return (-1); 104 } 105 106 DPRINTFX("adding breakpoint at 0x%lx", address); 107 108 stopped = 0; 109 if (phdl->status != PS_STOP) { 110 if (proc_stop(phdl) != 0) 111 return (-1); 112 stopped = 1; 113 } 114 115 /* 116 * Read the original instruction. 117 */ 118 caddr = address; 119 paddr = 0; 120 piod.piod_op = PIOD_READ_I; 121 piod.piod_offs = (void *)caddr; 122 piod.piod_addr = &paddr; 123 piod.piod_len = BREAKPOINT_INSTR_SZ; 124 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 125 DPRINTF("ERROR: couldn't read instruction at address 0x%" 126 PRIuPTR, address); 127 ret = -1; 128 goto done; 129 } 130 *saved = paddr; 131 /* 132 * Write a breakpoint instruction to that address. 133 */ 134 caddr = address; 135 paddr = BREAKPOINT_INSTR; 136 piod.piod_op = PIOD_WRITE_I; 137 piod.piod_offs = (void *)caddr; 138 piod.piod_addr = &paddr; 139 piod.piod_len = BREAKPOINT_INSTR_SZ; 140 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 141 DPRINTF("ERROR: couldn't write instruction at address 0x%" 142 PRIuPTR, address); 143 ret = -1; 144 goto done; 145 } 146 147 done: 148 if (stopped) 149 /* Restart the process if we had to stop it. */ 150 proc_continue(phdl); 151 152 return (ret); 153 } 154 155 int 156 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 157 unsigned long saved) 158 { 159 struct ptrace_io_desc piod; 160 unsigned long paddr, caddr; 161 int ret = 0, stopped; 162 163 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 164 phdl->status == PS_IDLE) { 165 errno = ENOENT; 166 return (-1); 167 } 168 169 DPRINTFX("removing breakpoint at 0x%lx", address); 170 171 stopped = 0; 172 if (phdl->status != PS_STOP) { 173 if (proc_stop(phdl) != 0) 174 return (-1); 175 stopped = 1; 176 } 177 178 /* 179 * Overwrite the breakpoint instruction that we setup previously. 180 */ 181 caddr = address; 182 paddr = saved; 183 piod.piod_op = PIOD_WRITE_I; 184 piod.piod_offs = (void *)caddr; 185 piod.piod_addr = &paddr; 186 piod.piod_len = BREAKPOINT_INSTR_SZ; 187 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 188 DPRINTF("ERROR: couldn't write instruction at address 0x%" 189 PRIuPTR, address); 190 ret = -1; 191 } 192 193 if (stopped) 194 /* Restart the process if we had to stop it. */ 195 proc_continue(phdl); 196 197 return (ret); 198 } 199 200 /* 201 * Decrement pc so that we delete the breakpoint at the correct 202 * address, i.e. at the BREAKPOINT_INSTR address. 203 * 204 * This is only needed on some architectures where the pc value 205 * when reading registers points at the instruction after the 206 * breakpoint, e.g. x86. 207 */ 208 void 209 proc_bkptregadj(unsigned long *pc) 210 { 211 212 (void)pc; 213 #ifdef BREAKPOINT_ADJUST_SZ 214 *pc = *pc - BREAKPOINT_ADJUST_SZ; 215 #endif 216 } 217 218 /* 219 * Step over the breakpoint. 220 */ 221 int 222 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 223 { 224 unsigned long pc; 225 unsigned long samesaved; 226 int status; 227 228 if (proc_regget(phdl, REG_PC, &pc) < 0) { 229 DPRINTFX("ERROR: couldn't get PC register"); 230 return (-1); 231 } 232 proc_bkptregadj(&pc); 233 if (proc_bkptdel(phdl, pc, saved) < 0) { 234 DPRINTFX("ERROR: couldn't delete breakpoint"); 235 return (-1); 236 } 237 /* 238 * Go back in time and step over the new instruction just 239 * set up by proc_bkptdel(). 240 */ 241 proc_regset(phdl, REG_PC, pc); 242 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 243 DPRINTFX("ERROR: ptrace step failed"); 244 return (-1); 245 } 246 proc_wstatus(phdl); 247 status = proc_getwstat(phdl); 248 if (!WIFSTOPPED(status)) { 249 DPRINTFX("ERROR: don't know why process stopped"); 250 return (-1); 251 } 252 /* 253 * Restore the breakpoint. The saved instruction should be 254 * the same as the one that we were passed in. 255 */ 256 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 257 DPRINTFX("ERROR: couldn't restore breakpoint"); 258 return (-1); 259 } 260 assert(samesaved == saved); 261 262 return (0); 263 } 264
Indexes created Tue Mar 03 05:31:39 UTC 2026