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