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 #else 48 #error "Add support for your architecture" 49 #endif 50 51 int 52 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 53 unsigned long *saved) 54 { 55 struct ptrace_io_desc piod; 56 unsigned long paddr, caddr; 57 58 *saved = 0; 59 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 60 phdl->status == PS_IDLE) { 61 errno = ENOENT; 62 return (-1); 63 } 64 65 /* 66 * Read the original instruction. 67 */ 68 caddr = address; 69 paddr = 0; 70 piod.piod_op = PIOD_READ_I; 71 piod.piod_offs = (void *)caddr; 72 piod.piod_addr = &paddr; 73 piod.piod_len = BREAKPOINT_INSTR_SZ; 74 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 75 DPRINTF("ERROR: couldn't read instruction at address 0x%" PRIuPTR, 76 address); 77 return (-1); 78 } 79 *saved = paddr; 80 /* 81 * Write a breakpoint instruction to that address. 82 */ 83 caddr = address; 84 paddr = BREAKPOINT_INSTR; 85 piod.piod_op = PIOD_WRITE_I; 86 piod.piod_offs = (void *)caddr; 87 piod.piod_addr = &paddr; 88 piod.piod_len = BREAKPOINT_INSTR_SZ; 89 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 90 warn("ERROR: couldn't write instruction at address 0x%" PRIuPTR, 91 address); 92 return (-1); 93 } 94 95 return (0); 96 } 97 98 int 99 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 100 unsigned long saved) 101 { 102 struct ptrace_io_desc piod; 103 unsigned long paddr, caddr; 104 105 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 106 phdl->status == PS_IDLE) { 107 errno = ENOENT; 108 return (-1); 109 } 110 DPRINTF("removing breakpoint at 0x%lx\n", address); 111 /* 112 * Overwrite the breakpoint instruction that we setup previously. 113 */ 114 caddr = address; 115 paddr = saved; 116 piod.piod_op = PIOD_WRITE_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 write instruction at address 0x%" PRIuPTR, 122 address); 123 return (-1); 124 } 125 126 return (0); 127 } 128 129 /* 130 * Decrement pc so that we delete the breakpoint at the correct 131 * address, i.e. at the BREAKPOINT_INSTR address. 132 */ 133 void 134 proc_bkptregadj(unsigned long *pc) 135 { 136 *pc = *pc - BREAKPOINT_INSTR_SZ; 137 } 138 139 /* 140 * Step over the breakpoint. 141 */ 142 int 143 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 144 { 145 unsigned long pc; 146 unsigned long samesaved; 147 int status; 148 149 if (proc_regget(phdl, REG_PC, &pc) < 0) { 150 warn("ERROR: couldn't get PC register"); 151 return (-1); 152 } 153 proc_bkptregadj(&pc); 154 if (proc_bkptdel(phdl, pc, saved) < 0) { 155 warn("ERROR: couldn't delete breakpoint"); 156 return (-1); 157 } 158 /* 159 * Go back in time and step over the new instruction just 160 * set up by proc_bkptdel(). 161 */ 162 proc_regset(phdl, REG_PC, pc); 163 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 164 warn("ERROR: ptrace step failed"); 165 return (-1); 166 } 167 proc_wstatus(phdl); 168 status = proc_getwstat(phdl); 169 if (!WIFSTOPPED(status)) { 170 warn("ERROR: don't know why process stopped"); 171 return (-1); 172 } 173 /* 174 * Restore the breakpoint. The saved instruction should be 175 * the same as the one that we were passed in. 176 */ 177 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 178 warn("ERROR: couldn't restore breakpoint"); 179 return (-1); 180 } 181 assert(samesaved == saved); 182 183 return (0); 184 } 185