proc_bkpt.c revision 1.1.1.1
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: head/lib/libproc/proc_bkpt.c 287106 2015-08-24 12:17:15Z andrew $"); 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#else 65#error "Add support for your architecture" 66#endif 67 68static int 69proc_stop(struct proc_handle *phdl) 70{ 71 int status; 72 73 if (kill(proc_getpid(phdl), SIGSTOP) == -1) { 74 DPRINTF("kill %d", proc_getpid(phdl)); 75 return (-1); 76 } else if (waitpid(proc_getpid(phdl), &status, WSTOPPED) == -1) { 77 DPRINTF("waitpid %d", proc_getpid(phdl)); 78 return (-1); 79 } else if (!WIFSTOPPED(status)) { 80 DPRINTFX("waitpid: unexpected status 0x%x", status); 81 return (-1); 82 } 83 84 return (0); 85} 86 87int 88proc_bkptset(struct proc_handle *phdl, uintptr_t address, 89 unsigned long *saved) 90{ 91 struct ptrace_io_desc piod; 92 unsigned long paddr, caddr; 93 int ret = 0, stopped; 94 95 *saved = 0; 96 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 97 phdl->status == PS_IDLE) { 98 errno = ENOENT; 99 return (-1); 100 } 101 102 DPRINTFX("adding breakpoint at 0x%lx", address); 103 104 stopped = 0; 105 if (phdl->status != PS_STOP) { 106 if (proc_stop(phdl) != 0) 107 return (-1); 108 stopped = 1; 109 } 110 111 /* 112 * Read the original instruction. 113 */ 114 caddr = address; 115 paddr = 0; 116 piod.piod_op = PIOD_READ_I; 117 piod.piod_offs = (void *)caddr; 118 piod.piod_addr = &paddr; 119 piod.piod_len = BREAKPOINT_INSTR_SZ; 120 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 121 DPRINTF("ERROR: couldn't read instruction at address 0x%" 122 PRIuPTR, address); 123 ret = -1; 124 goto done; 125 } 126 *saved = paddr; 127 /* 128 * Write a breakpoint instruction to that address. 129 */ 130 caddr = address; 131 paddr = BREAKPOINT_INSTR; 132 piod.piod_op = PIOD_WRITE_I; 133 piod.piod_offs = (void *)caddr; 134 piod.piod_addr = &paddr; 135 piod.piod_len = BREAKPOINT_INSTR_SZ; 136 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 137 DPRINTF("ERROR: couldn't write instruction at address 0x%" 138 PRIuPTR, address); 139 ret = -1; 140 goto done; 141 } 142 143done: 144 if (stopped) 145 /* Restart the process if we had to stop it. */ 146 proc_continue(phdl); 147 148 return (ret); 149} 150 151int 152proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 153 unsigned long saved) 154{ 155 struct ptrace_io_desc piod; 156 unsigned long paddr, caddr; 157 int ret = 0, stopped; 158 159 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 160 phdl->status == PS_IDLE) { 161 errno = ENOENT; 162 return (-1); 163 } 164 165 DPRINTFX("removing breakpoint at 0x%lx", address); 166 167 stopped = 0; 168 if (phdl->status != PS_STOP) { 169 if (proc_stop(phdl) != 0) 170 return (-1); 171 stopped = 1; 172 } 173 174 /* 175 * Overwrite the breakpoint instruction that we setup previously. 176 */ 177 caddr = address; 178 paddr = saved; 179 piod.piod_op = PIOD_WRITE_I; 180 piod.piod_offs = (void *)caddr; 181 piod.piod_addr = &paddr; 182 piod.piod_len = BREAKPOINT_INSTR_SZ; 183 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 184 DPRINTF("ERROR: couldn't write instruction at address 0x%" 185 PRIuPTR, address); 186 ret = -1; 187 } 188 189 if (stopped) 190 /* Restart the process if we had to stop it. */ 191 proc_continue(phdl); 192 193 return (ret); 194} 195 196/* 197 * Decrement pc so that we delete the breakpoint at the correct 198 * address, i.e. at the BREAKPOINT_INSTR address. 199 * 200 * This is only needed on some architectures where the pc value 201 * when reading registers points at the instruction after the 202 * breakpoint, e.g. x86. 203 */ 204void 205proc_bkptregadj(unsigned long *pc) 206{ 207 208 (void)pc; 209#ifdef BREAKPOINT_ADJUST_SZ 210 *pc = *pc - BREAKPOINT_ADJUST_SZ; 211#endif 212} 213 214/* 215 * Step over the breakpoint. 216 */ 217int 218proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 219{ 220 unsigned long pc; 221 unsigned long samesaved; 222 int status; 223 224 if (proc_regget(phdl, REG_PC, &pc) < 0) { 225 DPRINTFX("ERROR: couldn't get PC register"); 226 return (-1); 227 } 228 proc_bkptregadj(&pc); 229 if (proc_bkptdel(phdl, pc, saved) < 0) { 230 DPRINTFX("ERROR: couldn't delete breakpoint"); 231 return (-1); 232 } 233 /* 234 * Go back in time and step over the new instruction just 235 * set up by proc_bkptdel(). 236 */ 237 proc_regset(phdl, REG_PC, pc); 238 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 239 DPRINTFX("ERROR: ptrace step failed"); 240 return (-1); 241 } 242 proc_wstatus(phdl); 243 status = proc_getwstat(phdl); 244 if (!WIFSTOPPED(status)) { 245 DPRINTFX("ERROR: don't know why process stopped"); 246 return (-1); 247 } 248 /* 249 * Restore the breakpoint. The saved instruction should be 250 * the same as the one that we were passed in. 251 */ 252 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 253 DPRINTFX("ERROR: couldn't restore breakpoint"); 254 return (-1); 255 } 256 assert(samesaved == saved); 257 258 return (0); 259} 260