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 int ret = 0, stopped; 106 instr_t instr; 107 108 *saved = 0; 109 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 110 phdl->status == PS_IDLE) { 111 errno = ENOENT; 112 return (-1); 113 } 114 115 DPRINTFX("adding breakpoint at 0x%lx", (unsigned long)address); 116 117 stopped = 0; 118 if (phdl->status != PS_STOP) { 119 if (proc_stop(phdl) != 0) 120 return (-1); 121 stopped = 1; 122 } 123 124 /* 125 * Read the original instruction. 126 */ 127 instr = 0; 128 piod.piod_op = PIOD_READ_I; 129 piod.piod_offs = (void *)address; 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 instr = BREAKPOINT_INSTR; 143 piod.piod_op = PIOD_WRITE_I; 144 piod.piod_offs = (void *)address; 145 piod.piod_addr = &instr; 146 piod.piod_len = BREAKPOINT_INSTR_SZ; 147 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 148 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 149 (uintmax_t)address); 150 ret = -1; 151 goto done; 152 } 153 154 done: 155 if (stopped) 156 /* Restart the process if we had to stop it. */ 157 proc_continue(phdl); 158 159 return (ret); 160 } 161 162 int 163 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 164 unsigned long saved) 165 { 166 struct ptrace_io_desc piod; 167 int ret = 0, stopped; 168 instr_t instr; 169 170 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 171 phdl->status == PS_IDLE) { 172 errno = ENOENT; 173 return (-1); 174 } 175 176 DPRINTFX("removing breakpoint at 0x%lx", (unsigned long)address); 177 178 stopped = 0; 179 if (phdl->status != PS_STOP) { 180 if (proc_stop(phdl) != 0) 181 return (-1); 182 stopped = 1; 183 } 184 185 /* 186 * Overwrite the breakpoint instruction that we setup previously. 187 */ 188 instr = saved; 189 piod.piod_op = PIOD_WRITE_I; 190 piod.piod_offs = (void *)address; 191 piod.piod_addr = &instr; 192 piod.piod_len = BREAKPOINT_INSTR_SZ; 193 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 194 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 195 (uintmax_t)address); 196 ret = -1; 197 } 198 199 if (stopped) 200 /* Restart the process if we had to stop it. */ 201 proc_continue(phdl); 202 203 return (ret); 204 } 205 206 /* 207 * Decrement pc so that we delete the breakpoint at the correct 208 * address, i.e. at the BREAKPOINT_INSTR address. 209 * 210 * This is only needed on some architectures where the pc value 211 * when reading registers points at the instruction after the 212 * breakpoint, e.g. x86. 213 */ 214 void 215 proc_bkptregadj(unsigned long *pc) 216 { 217 218 (void)pc; 219 #ifdef BREAKPOINT_ADJUST_SZ 220 *pc = *pc - BREAKPOINT_ADJUST_SZ; 221 #endif 222 } 223 224 /* 225 * Step over the breakpoint. 226 */ 227 int 228 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 229 { 230 unsigned long pc; 231 unsigned long samesaved; 232 int status; 233 234 if (proc_regget(phdl, REG_PC, &pc) < 0) { 235 DPRINTFX("ERROR: couldn't get PC register"); 236 return (-1); 237 } 238 proc_bkptregadj(&pc); 239 if (proc_bkptdel(phdl, pc, saved) < 0) { 240 DPRINTFX("ERROR: couldn't delete breakpoint"); 241 return (-1); 242 } 243 /* 244 * Go back in time and step over the new instruction just 245 * set up by proc_bkptdel(). 246 */ 247 proc_regset(phdl, REG_PC, pc); 248 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 249 DPRINTFX("ERROR: ptrace step failed"); 250 return (-1); 251 } 252 proc_wstatus(phdl); 253 status = proc_getwstat(phdl); 254 if (!WIFSTOPPED(status)) { 255 DPRINTFX("ERROR: don't know why process stopped"); 256 return (-1); 257 } 258 /* 259 * Restore the breakpoint. The saved instruction should be 260 * the same as the one that we were passed in. 261 */ 262 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 263 DPRINTFX("ERROR: couldn't restore breakpoint"); 264 return (-1); 265 } 266 assert(samesaved == saved); 267 268 return (0); 269 } 270