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 #elif defined(__powerpc__) 51 #define BREAKPOINT_INSTR 0x7fe00008 /* trap */ 52 #define BREAKPOINT_INSTR_SZ 4 53 #else 54 #error "Add support for your architecture" 55 #endif 56 57 int 58 proc_bkptset(struct proc_handle *phdl, uintptr_t address, 59 unsigned long *saved) 60 { 61 struct ptrace_io_desc piod; 62 unsigned long paddr, caddr; 63 64 *saved = 0; 65 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 66 phdl->status == PS_IDLE) { 67 errno = ENOENT; 68 return (-1); 69 } 70 71 /* 72 * Read the original instruction. 73 */ 74 caddr = address; 75 paddr = 0; 76 piod.piod_op = PIOD_READ_I; 77 piod.piod_offs = (void *)caddr; 78 piod.piod_addr = &paddr; 79 piod.piod_len = BREAKPOINT_INSTR_SZ; 80 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 81 DPRINTF("ERROR: couldn't read instruction at address 0x%" PRIuPTR, 82 address); 83 return (-1); 84 } 85 *saved = paddr; 86 /* 87 * Write a breakpoint instruction to that address. 88 */ 89 caddr = address; 90 paddr = BREAKPOINT_INSTR; 91 piod.piod_op = PIOD_WRITE_I; 92 piod.piod_offs = (void *)caddr; 93 piod.piod_addr = &paddr; 94 piod.piod_len = BREAKPOINT_INSTR_SZ; 95 if (ptrace(PT_IO, proc_getpid(phdl), (caddr_t)&piod, 0) < 0) { 96 warn("ERROR: couldn't write instruction at address 0x%" PRIuPTR, 97 address); 98 return (-1); 99 } 100 101 return (0); 102 } 103 104 int 105 proc_bkptdel(struct proc_handle *phdl, uintptr_t address, 106 unsigned long saved) 107 { 108 struct ptrace_io_desc piod; 109 unsigned long paddr, caddr; 110 111 if (phdl->status == PS_DEAD || phdl->status == PS_UNDEAD || 112 phdl->status == PS_IDLE) { 113 errno = ENOENT; 114 return (-1); 115 } 116 DPRINTF("removing breakpoint at 0x%lx\n", address); 117 /* 118 * Overwrite the breakpoint instruction that we setup previously. 119 */ 120 caddr = address; 121 paddr = saved; 122 piod.piod_op = PIOD_WRITE_I; 123 piod.piod_offs = (void *)caddr; 124 piod.piod_addr = &paddr; 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 write instruction at address 0x%" PRIuPTR, 128 address); 129 return (-1); 130 } 131 132 return (0); 133 } 134 135 /* 136 * Decrement pc so that we delete the breakpoint at the correct 137 * address, i.e. at the BREAKPOINT_INSTR address. 138 */ 139 void 140 proc_bkptregadj(unsigned long *pc) 141 { 142 *pc = *pc - BREAKPOINT_INSTR_SZ; 143 } 144 145 /* 146 * Step over the breakpoint. 147 */ 148 int 149 proc_bkptexec(struct proc_handle *phdl, unsigned long saved) 150 { 151 unsigned long pc; 152 unsigned long samesaved; 153 int status; 154 155 if (proc_regget(phdl, REG_PC, &pc) < 0) { 156 warn("ERROR: couldn't get PC register"); 157 return (-1); 158 } 159 proc_bkptregadj(&pc); 160 if (proc_bkptdel(phdl, pc, saved) < 0) { 161 warn("ERROR: couldn't delete breakpoint"); 162 return (-1); 163 } 164 /* 165 * Go back in time and step over the new instruction just 166 * set up by proc_bkptdel(). 167 */ 168 proc_regset(phdl, REG_PC, pc); 169 if (ptrace(PT_STEP, proc_getpid(phdl), (caddr_t)1, 0) < 0) { 170 warn("ERROR: ptrace step failed"); 171 return (-1); 172 } 173 proc_wstatus(phdl); 174 status = proc_getwstat(phdl); 175 if (!WIFSTOPPED(status)) { 176 warn("ERROR: don't know why process stopped"); 177 return (-1); 178 } 179 /* 180 * Restore the breakpoint. The saved instruction should be 181 * the same as the one that we were passed in. 182 */ 183 if (proc_bkptset(phdl, pc, &samesaved) < 0) { 184 warn("ERROR: couldn't restore breakpoint"); 185 return (-1); 186 } 187 assert(samesaved == saved); 188 189 return (0); 190 } 191