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 37 #include <assert.h> 38 #include <err.h> 39 #include <errno.h> 40 #include <signal.h> 41 #include <stdio.h> 42 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 #define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ 55 #elif defined(__arm__) 56 #define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */ 57 #define BREAKPOINT_INSTR_SZ 4 58 #elif defined(__mips__) 59 #define BREAKPOINT_INSTR 0xd /* break */ 60 #define BREAKPOINT_INSTR_SZ 4 61 #elif defined(__powerpc__) 62 #define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 63 #define BREAKPOINT_INSTR_SZ 4 64 #elif defined(__riscv__) 65 #define BREAKPOINT_INSTR 0x00100073 /* sbreak */ 66 #define BREAKPOINT_INSTR_SZ 4 67 #else 68 #error "Add support for your architecture" 69 #endif 70 71 /* 72 * Use 4-bytes holder for breakpoint instruction on all the platforms. 73 * Works for x86 as well until it is endian-little platform. 74 * (We are coping one byte only on x86 from this 4-bytes piece of 75 * memory). 76 */ 77 typedef uint32_t instr_t; 78 79 static int 80 proc_stop(struct proc_handle *phdl) 81 { 82 int status; 83 84 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 85 DPRINTF("kill %d", proc_getpid(phdl)); 86 return (-1); 87 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 88 DPRINTF("waitpid %d", proc_getpid(phdl)); 89 return (-1); 90 } else if (!WIFSTOPPED(status)) { 91 DPRINTFX("waitpid: unexpected status 0x%x", status); 92 return (-1); 93 } 94 95 return (0); 96 } 97 98 int 99 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 100 unsigned long *saved) 101 { 102 struct ptrace_io_desc piod; 103 unsigned long caddr; 104 int ret = 0, stopped; 105 instr_t instr; 106 107 *saved = 0; 108 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 109 phdl->status == PS_IDLE) { 110 errno = ENOENT; 111 return (-1); 112 } 113 114 DPRINTFX("adding breakpoint at 0x%lx", address); 115 116 stopped = 0; 117 if (phdl->status != PS_STOP) { 118 if (proc_stop(phdl) != 0) 119 return (-1); 120 stopped = 1; 121 } 122 123 /* 124 * Read the original instruction. 125 */ 126 caddr = address; 127 instr = 0; 128 piod.piod_op = PIOD_READ_I; 129 piod.piod_offs = (void *)caddr; 130 piod.piod_addr = &instr; 131 piod.piod_len = BREAKPOINT_INSTR_SZ; 132 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 133 DPRINTF("ERROR: couldn't read instruction at address 0x%jx", 134 (uintmax_t)address); 135 ret = -1; 136 goto done; 137 } 138 *saved = instr; 139 /* 140 * Write a breakpoint instruction to that address. 141 */ 142 caddr = address; 143 instr = BREAKPOINT_INSTR; 144 piod.piod_op = PIOD_WRITE_I; 145 piod.piod_offs = (void *)caddr; 146 piod.piod_addr = &instr; 147 piod.piod_len = BREAKPOINT_INSTR_SZ; 148 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 149 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 150 (uintmax_t)address); 151 ret = -1; 152 goto done; 153 } 154 155 done: 156 if (stopped) 157 /* Restart the process if we had to stop it. */ 158 proc_continue(phdl); 159 160 return (ret); 161 } 162 163 int 164 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 165 unsigned long saved) 166 { 167 struct ptrace_io_desc piod; 168 unsigned long caddr; 169 int ret = 0, stopped; 170 instr_t instr; 171 172 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 173 phdl->status == PS_IDLE) { 174 errno = ENOENT; 175 return (-1); 176 } 177 178 DPRINTFX("removing breakpoint at 0x%lx", address); 179 180 stopped = 0; 181 if (phdl->status != PS_STOP) { 182 if (proc_stop(phdl) != 0) 183 return (-1); 184 stopped = 1; 185 } 186 187 /* 188 * Overwrite the breakpoint instruction that we setup previously. 189 */ 190 caddr = address; 191 instr = saved; 192 piod.piod_op = PIOD_WRITE_I; 193 piod.piod_offs = (void *)caddr; 194 piod.piod_addr = &instr; 195 piod.piod_len = BREAKPOINT_INSTR_SZ; 196 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 197 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 198 (uintmax_t)address); 199 ret = -1; 200 } 201 202 if (stopped) 203 /* Restart the process if we had to stop it. */ 204 proc_continue(phdl); 205 206 return (ret); 207 } 208 209 /* 210 * Decrement pc so that we delete the breakpoint at the correct 211 * address, i.e. at the BREAKPOINT_INSTR address. 212 * 213 * This is only needed on some architectures where the pc value 214 * when reading registers points at the instruction after the 215 * breakpoint, e.g. x86. 216 */ 217 void 218 proc_bkptregadj(unsigned long *pc) 219 { 220 221 (void)pc; 222 #ifdef BREAKPOINT_ADJUST_SZ 223 *pc = *pc - BREAKPOINT_ADJUST_SZ; 224 #endif 225 } 226 227 /* 228 * Step over the breakpoint. 229 */ 230 int 231 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 232 { 233 unsigned long pc; 234 unsigned long samesaved; 235 int status; 236 237 if (proc_regget(phdl, REG_PC, &pc) < 0) { 238 DPRINTFX("ERROR: couldn't get PC register"); 239 return (-1); 240 } 241 proc_bkptregadj(&pc); 242 if (proc_bkptdel(phdl, pc, saved) < 0) { 243 DPRINTFX("ERROR: couldn't delete breakpoint"); 244 return (-1); 245 } 246 /* 247 * Go back in time and step over the new instruction just 248 * set up by proc_bkptdel(). 249 */ 250 proc_regset(phdl, REG_PC, pc); 251 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 252 DPRINTFX("ERROR: ptrace step failed"); 253 return (-1); 254 } 255 proc_wstatus(phdl); 256 status = proc_getwstat(phdl); 257 if (!WIFSTOPPED(status)) { 258 DPRINTFX("ERROR: don't know why process stopped"); 259 return (-1); 260 } 261 /* 262 * Restore the breakpoint. The saved instruction should be 263 * the same as the one that we were passed in. 264 */ 265 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 266 DPRINTFX("ERROR: couldn't restore breakpoint"); 267 return (-1); 268 } 269 assert(samesaved == saved); 270 271 return (0); 272 } 273