1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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(__powerpc__) 61 #define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 62 #define BREAKPOINT_INSTR_SZ 4 63 #elif defined(__riscv) 64 #define BREAKPOINT_INSTR 0x00100073 /* sbreak */ 65 #define BREAKPOINT_INSTR_SZ 4 66 #else 67 #error "Add support for your architecture" 68 #endif 69 70 /* 71 * Use 4-bytes holder for breakpoint instruction on all the platforms. 72 * Works for x86 as well until it is endian-little platform. 73 * (We are coping one byte only on x86 from this 4-bytes piece of 74 * memory). 75 */ 76 typedef uint32_t instr_t; 77 78 static int 79 proc_stop(struct proc_handle *phdl) 80 { 81 int status; 82 83 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 84 DPRINTF("kill %d", proc_getpid(phdl)); 85 return (-1); 86 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 87 DPRINTF("waitpid %d", proc_getpid(phdl)); 88 return (-1); 89 } else if (!WIFSTOPPED(status)) { 90 DPRINTFX("waitpid: unexpected status 0x%x", status); 91 return (-1); 92 } 93 94 return (0); 95 } 96 97 int 98 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 99 unsigned long *saved) 100 { 101 struct ptrace_io_desc piod; 102 int ret = 0, stopped; 103 instr_t instr; 104 105 *saved = 0; 106 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 107 phdl->status == PS_IDLE) { 108 errno = ENOENT; 109 return (-1); 110 } 111 112 DPRINTFX("adding breakpoint at 0x%lx", (unsigned long)address); 113 114 stopped = 0; 115 if (phdl->status != PS_STOP) { 116 if (proc_stop(phdl) != 0) 117 return (-1); 118 stopped = 1; 119 } 120 121 /* 122 * Read the original instruction. 123 */ 124 instr = 0; 125 piod.piod_op = PIOD_READ_I; 126 piod.piod_offs = (void *)address; 127 piod.piod_addr = &instr; 128 piod.piod_len = BREAKPOINT_INSTR_SZ; 129 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 130 DPRINTF("ERROR: couldn't read instruction at address 0x%jx", 131 (uintmax_t)address); 132 ret = -1; 133 goto done; 134 } 135 *saved = instr; 136 /* 137 * Write a breakpoint instruction to that address. 138 */ 139 instr = BREAKPOINT_INSTR; 140 piod.piod_op = PIOD_WRITE_I; 141 piod.piod_offs = (void *)address; 142 piod.piod_addr = &instr; 143 piod.piod_len = BREAKPOINT_INSTR_SZ; 144 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 145 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 146 (uintmax_t)address); 147 ret = -1; 148 goto done; 149 } 150 151 done: 152 if (stopped) 153 /* Restart the process if we had to stop it. */ 154 proc_continue(phdl); 155 156 return (ret); 157 } 158 159 int 160 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 161 unsigned long saved) 162 { 163 struct ptrace_io_desc piod; 164 int ret = 0, stopped; 165 instr_t instr; 166 167 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 168 phdl->status == PS_IDLE) { 169 errno = ENOENT; 170 return (-1); 171 } 172 173 DPRINTFX("removing breakpoint at 0x%lx", (unsigned long)address); 174 175 stopped = 0; 176 if (phdl->status != PS_STOP) { 177 if (proc_stop(phdl) != 0) 178 return (-1); 179 stopped = 1; 180 } 181 182 /* 183 * Overwrite the breakpoint instruction that we setup previously. 184 */ 185 instr = saved; 186 piod.piod_op = PIOD_WRITE_I; 187 piod.piod_offs = (void *)address; 188 piod.piod_addr = &instr; 189 piod.piod_len = BREAKPOINT_INSTR_SZ; 190 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 191 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 192 (uintmax_t)address); 193 ret = -1; 194 } 195 196 if (stopped) 197 /* Restart the process if we had to stop it. */ 198 proc_continue(phdl); 199 200 return (ret); 201 } 202 203 /* 204 * Decrement pc so that we delete the breakpoint at the correct 205 * address, i.e. at the BREAKPOINT_INSTR address. 206 * 207 * This is only needed on some architectures where the pc value 208 * when reading registers points at the instruction after the 209 * breakpoint, e.g. x86. 210 */ 211 void 212 proc_bkptregadj(unsigned long *pc) 213 { 214 215 (void)pc; 216 #ifdef BREAKPOINT_ADJUST_SZ 217 *pc = *pc - BREAKPOINT_ADJUST_SZ; 218 #endif 219 } 220 221 /* 222 * Step over the breakpoint. 223 */ 224 int 225 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 226 { 227 unsigned long pc; 228 unsigned long samesaved; 229 int status; 230 231 if (proc_regget(phdl, REG_PC, &pc) < 0) { 232 DPRINTFX("ERROR: couldn't get PC register"); 233 return (-1); 234 } 235 proc_bkptregadj(&pc); 236 if (proc_bkptdel(phdl, pc, saved) < 0) { 237 DPRINTFX("ERROR: couldn't delete breakpoint"); 238 return (-1); 239 } 240 /* 241 * Go back in time and step over the new instruction just 242 * set up by proc_bkptdel(). 243 */ 244 proc_regset(phdl, REG_PC, pc); 245 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 246 DPRINTFX("ERROR: ptrace step failed"); 247 return (-1); 248 } 249 proc_wstatus(phdl); 250 status = proc_getwstat(phdl); 251 if (!WIFSTOPPED(status)) { 252 DPRINTFX("ERROR: don't know why process stopped"); 253 return (-1); 254 } 255 /* 256 * Restore the breakpoint. The saved instruction should be 257 * the same as the one that we were passed in. 258 */ 259 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 260 DPRINTFX("ERROR: couldn't restore breakpoint"); 261 return (-1); 262 } 263 assert(samesaved == saved); 264 265 return (0); 266 } 267