1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2010 The FreeBSD Foundation 5 * All rights reserved. 6 * 7 * This software was developed by Rui Paulo under sponsorship from the 8 * FreeBSD Foundation. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/types.h> 36 #include <sys/ptrace.h> 37 #include <sys/wait.h> 38 39 #include <assert.h> 40 #include <err.h> 41 #include <errno.h> 42 #include <signal.h> 43 #include <stdio.h> 44 45 #include "_libproc.h" 46 47 #if defined(__aarch64__) 48 #define AARCH64_BRK 0xd4200000 49 #define AARCH64_BRK_IMM16_SHIFT 5 50 #define AARCH64_BRK_IMM16_VAL (0xd << AARCH64_BRK_IMM16_SHIFT) 51 #define BREAKPOINT_INSTR (AARCH64_BRK | AARCH64_BRK_IMM16_VAL) 52 #define BREAKPOINT_INSTR_SZ 4 53 #elif defined(__amd64__) || defined(__i386__) 54 #define BREAKPOINT_INSTR 0xcc /* int 0x3 */ 55 #define BREAKPOINT_INSTR_SZ 1 56 #define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ 57 #elif defined(__arm__) 58 #define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */ 59 #define BREAKPOINT_INSTR_SZ 4 60 #elif defined(__mips__) 61 #define BREAKPOINT_INSTR 0xd /* break */ 62 #define BREAKPOINT_INSTR_SZ 4 63 #elif defined(__powerpc__) 64 #define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 65 #define BREAKPOINT_INSTR_SZ 4 66 #elif defined(__riscv) 67 #define BREAKPOINT_INSTR 0x00100073 /* sbreak */ 68 #define BREAKPOINT_INSTR_SZ 4 69 #else 70 #error "Add support for your architecture" 71 #endif 72 73 /* 74 * Use 4-bytes holder for breakpoint instruction on all the platforms. 75 * Works for x86 as well until it is endian-little platform. 76 * (We are coping one byte only on x86 from this 4-bytes piece of 77 * memory). 78 */ 79 typedef uint32_t instr_t; 80 81 static int 82 proc_stop(struct proc_handle *phdl) 83 { 84 int status; 85 86 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 87 DPRINTF("kill %d", proc_getpid(phdl)); 88 return (-1); 89 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 90 DPRINTF("waitpid %d", proc_getpid(phdl)); 91 return (-1); 92 } else if (!WIFSTOPPED(status)) { 93 DPRINTFX("waitpid: unexpected status 0x%x", status); 94 return (-1); 95 } 96 97 return (0); 98 } 99 100 int 101 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 102 unsigned long *saved) 103 { 104 struct ptrace_io_desc piod; 105 unsigned long caddr; 106 int ret = 0, stopped; 107 instr_t instr; 108 109 *saved = 0; 110 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 111 phdl->status == PS_IDLE) { 112 errno = ENOENT; 113 return (-1); 114 } 115 116 DPRINTFX("adding breakpoint at 0x%lx", address); 117 118 stopped = 0; 119 if (phdl->status != PS_STOP) { 120 if (proc_stop(phdl) != 0) 121 return (-1); 122 stopped = 1; 123 } 124 125 /* 126 * Read the original instruction. 127 */ 128 caddr = address; 129 instr = 0; 130 piod.piod_op = PIOD_READ_I; 131 piod.piod_offs = (void *)caddr; 132 piod.piod_addr = &instr; 133 piod.piod_len = BREAKPOINT_INSTR_SZ; 134 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 135 DPRINTF("ERROR: couldn't read instruction at address 0x%jx", 136 (uintmax_t)address); 137 ret = -1; 138 goto done; 139 } 140 *saved = instr; 141 /* 142 * Write a breakpoint instruction to that address. 143 */ 144 caddr = address; 145 instr = BREAKPOINT_INSTR; 146 piod.piod_op = PIOD_WRITE_I; 147 piod.piod_offs = (void *)caddr; 148 piod.piod_addr = &instr; 149 piod.piod_len = BREAKPOINT_INSTR_SZ; 150 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 151 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 152 (uintmax_t)address); 153 ret = -1; 154 goto done; 155 } 156 157 done: 158 if (stopped) 159 /* Restart the process if we had to stop it. */ 160 proc_continue(phdl); 161 162 return (ret); 163 } 164 165 int 166 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 167 unsigned long saved) 168 { 169 struct ptrace_io_desc piod; 170 unsigned long caddr; 171 int ret = 0, stopped; 172 instr_t instr; 173 174 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 175 phdl->status == PS_IDLE) { 176 errno = ENOENT; 177 return (-1); 178 } 179 180 DPRINTFX("removing breakpoint at 0x%lx", address); 181 182 stopped = 0; 183 if (phdl->status != PS_STOP) { 184 if (proc_stop(phdl) != 0) 185 return (-1); 186 stopped = 1; 187 } 188 189 /* 190 * Overwrite the breakpoint instruction that we setup previously. 191 */ 192 caddr = address; 193 instr = saved; 194 piod.piod_op = PIOD_WRITE_I; 195 piod.piod_offs = (void *)caddr; 196 piod.piod_addr = &instr; 197 piod.piod_len = BREAKPOINT_INSTR_SZ; 198 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 199 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 200 (uintmax_t)address); 201 ret = -1; 202 } 203 204 if (stopped) 205 /* Restart the process if we had to stop it. */ 206 proc_continue(phdl); 207 208 return (ret); 209 } 210 211 /* 212 * Decrement pc so that we delete the breakpoint at the correct 213 * address, i.e. at the BREAKPOINT_INSTR address. 214 * 215 * This is only needed on some architectures where the pc value 216 * when reading registers points at the instruction after the 217 * breakpoint, e.g. x86. 218 */ 219 void 220 proc_bkptregadj(unsigned long *pc) 221 { 222 223 (void)pc; 224 #ifdef BREAKPOINT_ADJUST_SZ 225 *pc = *pc - BREAKPOINT_ADJUST_SZ; 226 #endif 227 } 228 229 /* 230 * Step over the breakpoint. 231 */ 232 int 233 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 234 { 235 unsigned long pc; 236 unsigned long samesaved; 237 int status; 238 239 if (proc_regget(phdl, REG_PC, &pc) < 0) { 240 DPRINTFX("ERROR: couldn't get PC register"); 241 return (-1); 242 } 243 proc_bkptregadj(&pc); 244 if (proc_bkptdel(phdl, pc, saved) < 0) { 245 DPRINTFX("ERROR: couldn't delete breakpoint"); 246 return (-1); 247 } 248 /* 249 * Go back in time and step over the new instruction just 250 * set up by proc_bkptdel(). 251 */ 252 proc_regset(phdl, REG_PC, pc); 253 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 254 DPRINTFX("ERROR: ptrace step failed"); 255 return (-1); 256 } 257 proc_wstatus(phdl); 258 status = proc_getwstat(phdl); 259 if (!WIFSTOPPED(status)) { 260 DPRINTFX("ERROR: don't know why process stopped"); 261 return (-1); 262 } 263 /* 264 * Restore the breakpoint. The saved instruction should be 265 * the same as the one that we were passed in. 266 */ 267 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 268 DPRINTFX("ERROR: couldn't restore breakpoint"); 269 return (-1); 270 } 271 assert(samesaved == saved); 272 273 return (0); 274 } 275