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 <stdio.h> 41 #include <errno.h> 42 #include "_libproc.h" 43 44 #if defined(__i386__) || defined(__amd64__) 45 #define BREAKPOINT_INSTR 0xcc /* int 0x3 */ 46 #define BREAKPOINT_INSTR_SZ 1 47 #elif defined(__mips__) 48 #define BREAKPOINT_INSTR 0xd /* break */ 49 #define BREAKPOINT_INSTR_SZ 4 50 #else 51 #error "Add support for your architecture" 52 #endif 53 54 int 55 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 56 unsigned long *saved) 57 { 58 struct ptrace_io_desc piod; 59 unsigned long paddr, caddr; 60 61 *saved = 0; 62 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 63 phdl->status == PS_IDLE) { 64 errno = ENOENT; 65 return (-1); 66 } 67 68 /* 69 * Read the original instruction. 70 */ 71 caddr = address; 72 paddr = 0; 73 piod.piod_op = PIOD_READ_I; 74 piod.piod_offs = (void *)caddr; 75 piod.piod_addr = &paddr; 76 piod.piod_len = BREAKPOINT_INSTR_SZ; 77 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 78 DPRINTF("ERROR: couldn't read instruction at address 0x%" PRIuPTR, 79 address); 80 return (-1); 81 } 82 *saved = paddr; 83 /* 84 * Write a breakpoint instruction to that address. 85 */ 86 caddr = address; 87 paddr = BREAKPOINT_INSTR; 88 piod.piod_op = PIOD_WRITE_I; 89 piod.piod_offs = (void *)caddr; 90 piod.piod_addr = &paddr; 91 piod.piod_len = BREAKPOINT_INSTR_SZ; 92 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 93 warn("ERROR: couldn't write instruction at address 0x%" PRIuPTR, 94 address); 95 return (-1); 96 } 97 98 return (0); 99 } 100 101 int 102 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 103 unsigned long saved) 104 { 105 struct ptrace_io_desc piod; 106 unsigned long paddr, caddr; 107 108 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 109 phdl->status == PS_IDLE) { 110 errno = ENOENT; 111 return (-1); 112 } 113 DPRINTF("removing breakpoint at 0x%lx\n", address); 114 /* 115 * Overwrite the breakpoint instruction that we setup previously. 116 */ 117 caddr = address; 118 paddr = saved; 119 piod.piod_op = PIOD_WRITE_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 write instruction at address 0x%" PRIuPTR, 125 address); 126 return (-1); 127 } 128 129 return (0); 130 } 131 132 /* 133 * Decrement pc so that we delete the breakpoint at the correct 134 * address, i.e. at the BREAKPOINT_INSTR address. 135 */ 136 void 137 proc_bkptregadj(unsigned long *pc) 138 { 139 *pc = *pc - BREAKPOINT_INSTR_SZ; 140 } 141 142 /* 143 * Step over the breakpoint. 144 */ 145 int 146 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 147 { 148 unsigned long pc; 149 unsigned long samesaved; 150 int status; 151 152 if (proc_regget(phdl, REG_PC, &pc) < 0) { 153 warn("ERROR: couldn't get PC register"); 154 return (-1); 155 } 156 proc_bkptregadj(&pc); 157 if (proc_bkptdel(phdl, pc, saved) < 0) { 158 warn("ERROR: couldn't delete breakpoint"); 159 return (-1); 160 } 161 /* 162 * Go back in time and step over the new instruction just 163 * set up by proc_bkptdel(). 164 */ 165 proc_regset(phdl, REG_PC, pc); 166 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 167 warn("ERROR: ptrace step failed"); 168 return (-1); 169 } 170 proc_wstatus(phdl); 171 status = proc_getwstat(phdl); 172 if (!WIFSTOPPED(status)) { 173 warn("ERROR: don't know why process stopped"); 174 return (-1); 175 } 176 /* 177 * Restore the breakpoint. The saved instruction should be 178 * the same as the one that we were passed in. 179 */ 180 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 181 warn("ERROR: couldn't restore breakpoint"); 182 return (-1); 183 } 184 assert(samesaved == saved); 185 186 return (0); 187 } 188