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/types.h> 33#include <sys/ptrace.h> 34#include <sys/wait.h> 35 36#include <assert.h> 37#include <err.h> 38#include <errno.h> 39#include <signal.h> 40#include <stdio.h> 41 42#include "_libproc.h" 43 44#if defined(__aarch64__) 45#define AARCH64_BRK 0xd4200000 46#define AARCH64_BRK_IMM16_SHIFT 5 47#define AARCH64_BRK_IMM16_VAL (0xd << AARCH64_BRK_IMM16_SHIFT) 48#define BREAKPOINT_INSTR (AARCH64_BRK | AARCH64_BRK_IMM16_VAL) 49#define BREAKPOINT_INSTR_SZ 4 50#elif defined(__amd64__) || defined(__i386__) 51#define BREAKPOINT_INSTR 0xcc /* int 0x3 */ 52#define BREAKPOINT_INSTR_SZ 1 53#define BREAKPOINT_ADJUST_SZ BREAKPOINT_INSTR_SZ 54#elif defined(__arm__) 55#define BREAKPOINT_INSTR 0xe7ffffff /* bkpt */ 56#define BREAKPOINT_INSTR_SZ 4 57#elif defined(__powerpc__) 58#define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 59#define BREAKPOINT_INSTR_SZ 4 60#elif defined(__riscv) 61#define BREAKPOINT_INSTR 0x00100073 /* sbreak */ 62#define BREAKPOINT_INSTR_SZ 4 63#else 64#error "Add support for your architecture" 65#endif 66 67/* 68 * Use 4-bytes holder for breakpoint instruction on all the platforms. 69 * Works for x86 as well until it is endian-little platform. 70 * (We are coping one byte only on x86 from this 4-bytes piece of 71 * memory). 72 */ 73typedef uint32_t instr_t; 74 75static int 76proc_stop(struct proc_handle *phdl) 77{ 78 int status; 79 80 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 81 DPRINTF("kill %d", proc_getpid(phdl)); 82 return (-1); 83 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 84 DPRINTF("waitpid %d", proc_getpid(phdl)); 85 return (-1); 86 } else if (!WIFSTOPPED(status)) { 87 DPRINTFX("waitpid: unexpected status 0x%x", status); 88 return (-1); 89 } 90 91 return (0); 92} 93 94int 95proc_bkptset(struct proc_handle *phdl, uintptr_t address, 96 unsigned long *saved) 97{ 98 struct ptrace_io_desc piod; 99 int ret = 0, stopped; 100 instr_t instr; 101 102 *saved = 0; 103 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 104 phdl->status == PS_IDLE) { 105 errno = ENOENT; 106 return (-1); 107 } 108 109 DPRINTFX("adding breakpoint at 0x%lx", (unsigned long)address); 110 111 stopped = 0; 112 if (phdl->status != PS_STOP) { 113 if (proc_stop(phdl) != 0) 114 return (-1); 115 stopped = 1; 116 } 117 118 /* 119 * Read the original instruction. 120 */ 121 instr = 0; 122 piod.piod_op = PIOD_READ_I; 123 piod.piod_offs = (void *)address; 124 piod.piod_addr = &instr; 125 piod.piod_len = BREAKPOINT_INSTR_SZ; 126 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 127 DPRINTF("ERROR: couldn't read instruction at address 0x%jx", 128 (uintmax_t)address); 129 ret = -1; 130 goto done; 131 } 132 *saved = instr; 133 /* 134 * Write a breakpoint instruction to that address. 135 */ 136 instr = BREAKPOINT_INSTR; 137 piod.piod_op = PIOD_WRITE_I; 138 piod.piod_offs = (void *)address; 139 piod.piod_addr = &instr; 140 piod.piod_len = BREAKPOINT_INSTR_SZ; 141 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 142 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 143 (uintmax_t)address); 144 ret = -1; 145 goto done; 146 } 147 148done: 149 if (stopped) 150 /* Restart the process if we had to stop it. */ 151 proc_continue(phdl); 152 153 return (ret); 154} 155 156int 157proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 158 unsigned long saved) 159{ 160 struct ptrace_io_desc piod; 161 int ret = 0, stopped; 162 instr_t instr; 163 164 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 165 phdl->status == PS_IDLE) { 166 errno = ENOENT; 167 return (-1); 168 } 169 170 DPRINTFX("removing breakpoint at 0x%lx", (unsigned long)address); 171 172 stopped = 0; 173 if (phdl->status != PS_STOP) { 174 if (proc_stop(phdl) != 0) 175 return (-1); 176 stopped = 1; 177 } 178 179 /* 180 * Overwrite the breakpoint instruction that we setup previously. 181 */ 182 instr = saved; 183 piod.piod_op = PIOD_WRITE_I; 184 piod.piod_offs = (void *)address; 185 piod.piod_addr = &instr; 186 piod.piod_len = BREAKPOINT_INSTR_SZ; 187 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 188 DPRINTF("ERROR: couldn't write instruction at address 0x%jx", 189 (uintmax_t)address); 190 ret = -1; 191 } 192 193 if (stopped) 194 /* Restart the process if we had to stop it. */ 195 proc_continue(phdl); 196 197 return (ret); 198} 199 200/* 201 * Decrement pc so that we delete the breakpoint at the correct 202 * address, i.e. at the BREAKPOINT_INSTR address. 203 * 204 * This is only needed on some architectures where the pc value 205 * when reading registers points at the instruction after the 206 * breakpoint, e.g. x86. 207 */ 208void 209proc_bkptregadj(unsigned long *pc) 210{ 211 212 (void)pc; 213#ifdef BREAKPOINT_ADJUST_SZ 214 *pc = *pc - BREAKPOINT_ADJUST_SZ; 215#endif 216} 217 218/* 219 * Step over the breakpoint. 220 */ 221int 222proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 223{ 224 unsigned long pc; 225 unsigned long samesaved; 226 int status; 227 228 if (proc_regget(phdl, REG_PC, &pc) < 0) { 229 DPRINTFX("ERROR: couldn't get PC register"); 230 return (-1); 231 } 232 proc_bkptregadj(&pc); 233 if (proc_bkptdel(phdl, pc, saved) < 0) { 234 DPRINTFX("ERROR: couldn't delete breakpoint"); 235 return (-1); 236 } 237 /* 238 * Go back in time and step over the new instruction just 239 * set up by proc_bkptdel(). 240 */ 241 proc_regset(phdl, REG_PC, pc); 242 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 243 DPRINTFX("ERROR: ptrace step failed"); 244 return (-1); 245 } 246 proc_wstatus(phdl); 247 status = proc_getwstat(phdl); 248 if (!WIFSTOPPED(status)) { 249 DPRINTFX("ERROR: don't know why process stopped"); 250 return (-1); 251 } 252 /* 253 * Restore the breakpoint. The saved instruction should be 254 * the same as the one that we were passed in. 255 */ 256 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 257 DPRINTFX("ERROR: couldn't restore breakpoint"); 258 return (-1); 259 } 260 assert(samesaved == saved); 261 262 return (0); 263} 264