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