Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Kernel Probes (KProbes) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation; either version 2 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * This program is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write to the Free Software |
| 16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 17 | * |
| 18 | * Copyright (C) IBM Corporation, 2002, 2004 |
| 19 | * |
| 20 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
| 21 | * Probes initial implementation ( includes contributions from |
| 22 | * Rusty Russell). |
| 23 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
| 24 | * interface to access function arguments. |
| 25 | * 2004-Nov Ananth N Mavinakayanahalli <ananth@in.ibm.com> kprobes port |
| 26 | * for PPC64 |
| 27 | */ |
| 28 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 29 | #include <linux/kprobes.h> |
| 30 | #include <linux/ptrace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | #include <linux/preempt.h> |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 32 | #include <linux/module.h> |
Christoph Hellwig | 1eeb66a | 2007-05-08 00:27:03 -0700 | [diff] [blame] | 33 | #include <linux/kdebug.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 34 | #include <linux/slab.h> |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 35 | #include <asm/cacheflush.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | #include <asm/sstep.h> |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 37 | #include <asm/uaccess.h> |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 38 | #include <asm/system.h> |
| 39 | |
Dave Kleikamp | 172ae2e | 2010-02-08 11:50:57 +0000 | [diff] [blame] | 40 | #ifdef CONFIG_PPC_ADV_DEBUG_REGS |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 41 | #define MSR_SINGLESTEP (MSR_DE) |
| 42 | #else |
| 43 | #define MSR_SINGLESTEP (MSR_SE) |
| 44 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 46 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| 47 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | |
Masami Hiramatsu | f438d91 | 2007-10-16 01:27:49 -0700 | [diff] [blame] | 49 | struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; |
| 50 | |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 51 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | { |
Ananth N Mavinakayanahalli | 63224d1e8 | 2005-06-08 15:49:41 -0700 | [diff] [blame] | 53 | int ret = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | kprobe_opcode_t insn = *p->addr; |
| 55 | |
Ananth N Mavinakayanahalli | 63224d1e8 | 2005-06-08 15:49:41 -0700 | [diff] [blame] | 56 | if ((unsigned long)p->addr & 0x03) { |
| 57 | printk("Attempt to register kprobe at an unaligned address\n"); |
| 58 | ret = -EINVAL; |
Kumar Gala | 8209003 | 2007-02-06 22:55:19 -0600 | [diff] [blame] | 59 | } else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) { |
| 60 | printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n"); |
Ananth N Mavinakayanahalli | 63224d1e8 | 2005-06-08 15:49:41 -0700 | [diff] [blame] | 61 | ret = -EINVAL; |
| 62 | } |
Ananth N Mavinakayanahalli | 9ec4b1f | 2005-06-27 15:17:01 -0700 | [diff] [blame] | 63 | |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 64 | /* insn must be on a special executable page on ppc64. This is |
| 65 | * not explicitly required on ppc32 (right now), but it doesn't hurt */ |
Ananth N Mavinakayanahalli | 9ec4b1f | 2005-06-27 15:17:01 -0700 | [diff] [blame] | 66 | if (!ret) { |
Ananth N Mavinakayanahalli | 2d8ab6a | 2005-10-01 13:14:17 -0400 | [diff] [blame] | 67 | p->ainsn.insn = get_insn_slot(); |
Ananth N Mavinakayanahalli | 9ec4b1f | 2005-06-27 15:17:01 -0700 | [diff] [blame] | 68 | if (!p->ainsn.insn) |
| 69 | ret = -ENOMEM; |
| 70 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | |
Anil S Keshavamurthy | 49a2a1b | 2006-01-09 20:52:43 -0800 | [diff] [blame] | 72 | if (!ret) { |
Ananth N Mavinakayanahalli | e6349a9 | 2007-04-18 15:57:51 +1000 | [diff] [blame] | 73 | memcpy(p->ainsn.insn, p->addr, |
| 74 | MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
Anil S Keshavamurthy | 49a2a1b | 2006-01-09 20:52:43 -0800 | [diff] [blame] | 75 | p->opcode = *p->addr; |
Ananth N Mavinakayanahalli | 83db3dd | 2006-08-11 17:01:34 +0530 | [diff] [blame] | 76 | flush_icache_range((unsigned long)p->ainsn.insn, |
| 77 | (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t)); |
Anil S Keshavamurthy | 49a2a1b | 2006-01-09 20:52:43 -0800 | [diff] [blame] | 78 | } |
| 79 | |
Ananth N Mavinakayanahalli | e6349a9 | 2007-04-18 15:57:51 +1000 | [diff] [blame] | 80 | p->ainsn.boostable = 0; |
Anil S Keshavamurthy | 49a2a1b | 2006-01-09 20:52:43 -0800 | [diff] [blame] | 81 | return ret; |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 82 | } |
| 83 | |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 84 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 85 | { |
| 86 | *p->addr = BREAKPOINT_INSTRUCTION; |
| 87 | flush_icache_range((unsigned long) p->addr, |
| 88 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
| 89 | } |
| 90 | |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 91 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 92 | { |
| 93 | *p->addr = p->opcode; |
| 94 | flush_icache_range((unsigned long) p->addr, |
| 95 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | } |
| 97 | |
Ananth N Mavinakayanahalli | 0498b63 | 2006-01-09 20:52:46 -0800 | [diff] [blame] | 98 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | { |
Masami Hiramatsu | 1294156 | 2009-01-06 14:41:50 -0800 | [diff] [blame] | 100 | if (p->ainsn.insn) { |
| 101 | free_insn_slot(p->ainsn.insn, 0); |
| 102 | p->ainsn.insn = NULL; |
| 103 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 104 | } |
| 105 | |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 106 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 107 | { |
Kumar Gala | b76e59d | 2008-06-26 01:57:58 -0500 | [diff] [blame] | 108 | /* We turn off async exceptions to ensure that the single step will |
| 109 | * be for the instruction we have the kprobe on, if we dont its |
| 110 | * possible we'd get the single step reported for an exception handler |
| 111 | * like Decrementer or External Interrupt */ |
| 112 | regs->msr &= ~MSR_EE; |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 113 | regs->msr |= MSR_SINGLESTEP; |
Dave Kleikamp | 172ae2e | 2010-02-08 11:50:57 +0000 | [diff] [blame] | 114 | #ifdef CONFIG_PPC_ADV_DEBUG_REGS |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 115 | regs->msr &= ~MSR_CE; |
| 116 | mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM); |
Dave Kleikamp | 221c185 | 2010-03-05 10:43:24 +0000 | [diff] [blame] | 117 | #ifdef CONFIG_PPC_47x |
| 118 | isync(); |
| 119 | #endif |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 120 | #endif |
Ananth N Mavinakayanahalli | 9ec4b1f | 2005-06-27 15:17:01 -0700 | [diff] [blame] | 121 | |
Ananth N Mavinakayanahalli | 0ccde0a | 2006-04-28 17:38:42 +0530 | [diff] [blame] | 122 | /* |
| 123 | * On powerpc we should single step on the original |
| 124 | * instruction even if the probed insn is a trap |
| 125 | * variant as values in regs could play a part in |
| 126 | * if the trap is taken or not |
| 127 | */ |
| 128 | regs->nip = (unsigned long)p->ainsn.insn; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | } |
| 130 | |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 131 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 132 | { |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 133 | kcb->prev_kprobe.kp = kprobe_running(); |
| 134 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 135 | kcb->prev_kprobe.saved_msr = kcb->kprobe_saved_msr; |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 136 | } |
| 137 | |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 138 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 139 | { |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 140 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
| 141 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 142 | kcb->kprobe_saved_msr = kcb->prev_kprobe.saved_msr; |
| 143 | } |
| 144 | |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 145 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 146 | struct kprobe_ctlblk *kcb) |
| 147 | { |
| 148 | __get_cpu_var(current_kprobe) = p; |
| 149 | kcb->kprobe_saved_msr = regs->msr; |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 150 | } |
| 151 | |
Christoph Hellwig | 4c4308c | 2007-05-08 00:34:14 -0700 | [diff] [blame] | 152 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 153 | struct pt_regs *regs) |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 154 | { |
Christoph Hellwig | 4c4308c | 2007-05-08 00:34:14 -0700 | [diff] [blame] | 155 | ri->ret_addr = (kprobe_opcode_t *)regs->link; |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 156 | |
Christoph Hellwig | 4c4308c | 2007-05-08 00:34:14 -0700 | [diff] [blame] | 157 | /* Replace the return addr with trampoline addr */ |
| 158 | regs->link = (unsigned long)kretprobe_trampoline; |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 159 | } |
| 160 | |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 161 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 162 | { |
| 163 | struct kprobe *p; |
| 164 | int ret = 0; |
| 165 | unsigned int *addr = (unsigned int *)regs->nip; |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 166 | struct kprobe_ctlblk *kcb; |
| 167 | |
| 168 | /* |
| 169 | * We don't want to be preempted for the entire |
| 170 | * duration of kprobe processing |
| 171 | */ |
| 172 | preempt_disable(); |
| 173 | kcb = get_kprobe_ctlblk(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 174 | |
| 175 | /* Check we're not actually recursing */ |
| 176 | if (kprobe_running()) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 177 | p = get_kprobe(addr); |
| 178 | if (p) { |
Keshavamurthy Anil S | deac66a | 2005-09-06 15:19:35 -0700 | [diff] [blame] | 179 | kprobe_opcode_t insn = *p->ainsn.insn; |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 180 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
Keshavamurthy Anil S | deac66a | 2005-09-06 15:19:35 -0700 | [diff] [blame] | 181 | is_trap(insn)) { |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 182 | /* Turn off 'trace' bits */ |
| 183 | regs->msr &= ~MSR_SINGLESTEP; |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 184 | regs->msr |= kcb->kprobe_saved_msr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 185 | goto no_kprobe; |
| 186 | } |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 187 | /* We have reentered the kprobe_handler(), since |
| 188 | * another probe was hit while within the handler. |
| 189 | * We here save the original kprobes variables and |
| 190 | * just single step on the instruction of the new probe |
| 191 | * without calling any user handlers. |
| 192 | */ |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 193 | save_previous_kprobe(kcb); |
| 194 | set_current_kprobe(p, regs, kcb); |
| 195 | kcb->kprobe_saved_msr = regs->msr; |
Keshavamurthy Anil S | bf8d5c5 | 2005-12-12 00:37:34 -0800 | [diff] [blame] | 196 | kprobes_inc_nmissed_count(p); |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 197 | prepare_singlestep(p, regs); |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 198 | kcb->kprobe_status = KPROBE_REENTER; |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 199 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 200 | } else { |
Keshavamurthy Anil S | eb3a729 | 2006-01-11 12:17:42 -0800 | [diff] [blame] | 201 | if (*addr != BREAKPOINT_INSTRUCTION) { |
| 202 | /* If trap variant, then it belongs not to us */ |
| 203 | kprobe_opcode_t cur_insn = *addr; |
| 204 | if (is_trap(cur_insn)) |
| 205 | goto no_kprobe; |
| 206 | /* The breakpoint instruction was removed by |
| 207 | * another cpu right after we hit, no further |
| 208 | * handling of this interrupt is appropriate |
| 209 | */ |
| 210 | ret = 1; |
| 211 | goto no_kprobe; |
| 212 | } |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 213 | p = __get_cpu_var(current_kprobe); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | if (p->break_handler && p->break_handler(p, regs)) { |
| 215 | goto ss_probe; |
| 216 | } |
| 217 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 218 | goto no_kprobe; |
| 219 | } |
| 220 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | p = get_kprobe(addr); |
| 222 | if (!p) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 223 | if (*addr != BREAKPOINT_INSTRUCTION) { |
| 224 | /* |
| 225 | * PowerPC has multiple variants of the "trap" |
| 226 | * instruction. If the current instruction is a |
| 227 | * trap variant, it could belong to someone else |
| 228 | */ |
| 229 | kprobe_opcode_t cur_insn = *addr; |
Keshavamurthy Anil S | deac66a | 2005-09-06 15:19:35 -0700 | [diff] [blame] | 230 | if (is_trap(cur_insn)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 231 | goto no_kprobe; |
| 232 | /* |
| 233 | * The breakpoint instruction was removed right |
| 234 | * after we hit it. Another cpu has removed |
| 235 | * either a probepoint or a debugger breakpoint |
| 236 | * at this address. In either case, no further |
| 237 | * handling of this interrupt is appropriate. |
| 238 | */ |
| 239 | ret = 1; |
| 240 | } |
| 241 | /* Not one of ours: let kernel handle it */ |
| 242 | goto no_kprobe; |
| 243 | } |
| 244 | |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 245 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| 246 | set_current_kprobe(p, regs, kcb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | if (p->pre_handler && p->pre_handler(p, regs)) |
| 248 | /* handler has already set things up, so skip ss setup */ |
| 249 | return 1; |
| 250 | |
| 251 | ss_probe: |
Ananth N Mavinakayanahalli | e6349a9 | 2007-04-18 15:57:51 +1000 | [diff] [blame] | 252 | if (p->ainsn.boostable >= 0) { |
| 253 | unsigned int insn = *p->ainsn.insn; |
| 254 | |
| 255 | /* regs->nip is also adjusted if emulate_step returns 1 */ |
| 256 | ret = emulate_step(regs, insn); |
| 257 | if (ret > 0) { |
| 258 | /* |
| 259 | * Once this instruction has been boosted |
| 260 | * successfully, set the boostable flag |
| 261 | */ |
| 262 | if (unlikely(p->ainsn.boostable == 0)) |
| 263 | p->ainsn.boostable = 1; |
| 264 | |
| 265 | if (p->post_handler) |
| 266 | p->post_handler(p, regs, 0); |
| 267 | |
| 268 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 269 | reset_current_kprobe(); |
| 270 | preempt_enable_no_resched(); |
| 271 | return 1; |
| 272 | } else if (ret < 0) { |
| 273 | /* |
| 274 | * We don't allow kprobes on mtmsr(d)/rfi(d), etc. |
| 275 | * So, we should never get here... but, its still |
| 276 | * good to catch them, just in case... |
| 277 | */ |
| 278 | printk("Can't step on instruction %x\n", insn); |
| 279 | BUG(); |
| 280 | } else if (ret == 0) |
| 281 | /* This instruction can't be boosted */ |
| 282 | p->ainsn.boostable = -1; |
| 283 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 284 | prepare_singlestep(p, regs); |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 285 | kcb->kprobe_status = KPROBE_HIT_SS; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 286 | return 1; |
| 287 | |
| 288 | no_kprobe: |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 289 | preempt_enable_no_resched(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 290 | return ret; |
| 291 | } |
| 292 | |
| 293 | /* |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 294 | * Function return probe trampoline: |
| 295 | * - init_kprobes() establishes a probepoint here |
| 296 | * - When the probed function returns, this probe |
| 297 | * causes the handlers to fire |
| 298 | */ |
Ananth N Mavinakayanahalli | 66200ea | 2008-02-15 21:59:17 +1100 | [diff] [blame] | 299 | static void __used kretprobe_trampoline_holder(void) |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 300 | { |
| 301 | asm volatile(".global kretprobe_trampoline\n" |
| 302 | "kretprobe_trampoline:\n" |
| 303 | "nop\n"); |
| 304 | } |
| 305 | |
| 306 | /* |
| 307 | * Called when the probe at kretprobe trampoline is hit |
| 308 | */ |
Ananth N Mavinakayanahalli | 66200ea | 2008-02-15 21:59:17 +1100 | [diff] [blame] | 309 | static int __kprobes trampoline_probe_handler(struct kprobe *p, |
| 310 | struct pt_regs *regs) |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 311 | { |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 312 | struct kretprobe_instance *ri = NULL; |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 313 | struct hlist_head *head, empty_rp; |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 314 | struct hlist_node *node, *tmp; |
Ananth N Mavinakayanahalli | 991a51d | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 315 | unsigned long flags, orig_ret_address = 0; |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 316 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
| 317 | |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 318 | INIT_HLIST_HEAD(&empty_rp); |
Srinivasa D S | ef53d9c | 2008-07-25 01:46:04 -0700 | [diff] [blame] | 319 | kretprobe_hash_lock(current, &head, &flags); |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 320 | |
| 321 | /* |
| 322 | * It is possible to have multiple instances associated with a given |
| 323 | * task either because an multiple functions in the call path |
Frederik Schwarzer | 025dfda | 2008-10-16 19:02:37 +0200 | [diff] [blame] | 324 | * have a return probe installed on them, and/or more than one return |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 325 | * return probe was registered for a target function. |
| 326 | * |
| 327 | * We can handle this because: |
| 328 | * - instances are always inserted at the head of the list |
| 329 | * - when multiple return probes are registered for the same |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 330 | * function, the first instance's ret_addr will point to the |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 331 | * real return address, and all the rest will point to |
| 332 | * kretprobe_trampoline |
| 333 | */ |
| 334 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 335 | if (ri->task != current) |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 336 | /* another task is sharing our hash bucket */ |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 337 | continue; |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 338 | |
| 339 | if (ri->rp && ri->rp->handler) |
| 340 | ri->rp->handler(ri, regs); |
| 341 | |
| 342 | orig_ret_address = (unsigned long)ri->ret_addr; |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 343 | recycle_rp_inst(ri, &empty_rp); |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 344 | |
| 345 | if (orig_ret_address != trampoline_address) |
| 346 | /* |
| 347 | * This is the real return address. Any other |
| 348 | * instances associated with this task are for |
| 349 | * other calls deeper on the call stack |
| 350 | */ |
| 351 | break; |
| 352 | } |
| 353 | |
Ananth N Mavinakayanahalli | 0f95b7f | 2007-05-08 00:28:27 -0700 | [diff] [blame] | 354 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 355 | regs->nip = orig_ret_address; |
| 356 | |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 357 | reset_current_kprobe(); |
Srinivasa D S | ef53d9c | 2008-07-25 01:46:04 -0700 | [diff] [blame] | 358 | kretprobe_hash_unlock(current, &flags); |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 359 | preempt_enable_no_resched(); |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 360 | |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 361 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
| 362 | hlist_del(&ri->hlist); |
| 363 | kfree(ri); |
| 364 | } |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 365 | /* |
| 366 | * By returning a non-zero value, we are telling |
| 367 | * kprobe_handler() that we don't want the post_handler |
| 368 | * to run (and have re-enabled preemption) |
| 369 | */ |
| 370 | return 1; |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 371 | } |
| 372 | |
| 373 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 374 | * Called after single-stepping. p->addr is the address of the |
| 375 | * instruction whose first byte has been replaced by the "breakpoint" |
| 376 | * instruction. To avoid the SMP problems that can occur when we |
| 377 | * temporarily put back the original opcode to single-step, we |
| 378 | * single-stepped a copy of the instruction. The address of this |
| 379 | * copy is p->ainsn.insn. |
| 380 | */ |
Prasanna S Panchamukhi | 46dbe2f | 2006-04-18 22:22:01 -0700 | [diff] [blame] | 381 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 382 | { |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 383 | struct kprobe *cur = kprobe_running(); |
| 384 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 385 | |
| 386 | if (!cur) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 387 | return 0; |
| 388 | |
Kumar Gala | b76e59d | 2008-06-26 01:57:58 -0500 | [diff] [blame] | 389 | /* make sure we got here for instruction we have a kprobe on */ |
| 390 | if (((unsigned long)cur->ainsn.insn + 4) != regs->nip) |
| 391 | return 0; |
| 392 | |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 393 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
| 394 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 395 | cur->post_handler(cur, regs, 0); |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 396 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 397 | |
Ananth N Mavinakayanahalli | db97bc7 | 2010-05-27 19:19:20 +0000 | [diff] [blame] | 398 | /* Adjust nip to after the single-stepped instruction */ |
| 399 | regs->nip = (unsigned long)cur->addr + 4; |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 400 | regs->msr |= kcb->kprobe_saved_msr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 401 | |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 402 | /*Restore back the original saved kprobes variables and continue. */ |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 403 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 404 | restore_previous_kprobe(kcb); |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 405 | goto out; |
| 406 | } |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 407 | reset_current_kprobe(); |
Prasanna S Panchamukhi | 42cc206 | 2005-06-23 00:09:38 -0700 | [diff] [blame] | 408 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 409 | preempt_enable_no_resched(); |
| 410 | |
| 411 | /* |
| 412 | * if somebody else is singlestepping across a probe point, msr |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 413 | * will have DE/SE set, in which case, continue the remaining processing |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 414 | * of do_debug, as if this is not a probe hit. |
| 415 | */ |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 416 | if (regs->msr & MSR_SINGLESTEP) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 417 | return 0; |
| 418 | |
| 419 | return 1; |
| 420 | } |
| 421 | |
Christoph Hellwig | 9f90b99 | 2007-04-30 11:56:46 +0100 | [diff] [blame] | 422 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 423 | { |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 424 | struct kprobe *cur = kprobe_running(); |
| 425 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 426 | const struct exception_table_entry *entry; |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 427 | |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 428 | switch(kcb->kprobe_status) { |
| 429 | case KPROBE_HIT_SS: |
| 430 | case KPROBE_REENTER: |
| 431 | /* |
| 432 | * We are here because the instruction being single |
| 433 | * stepped caused a page fault. We reset the current |
| 434 | * kprobe and the nip points back to the probe address |
| 435 | * and allow the page fault handler to continue as a |
| 436 | * normal page fault. |
| 437 | */ |
| 438 | regs->nip = (unsigned long)cur->addr; |
Kumar Gala | f827962 | 2008-06-26 02:01:37 -0500 | [diff] [blame] | 439 | regs->msr &= ~MSR_SINGLESTEP; /* Turn off 'trace' bits */ |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 440 | regs->msr |= kcb->kprobe_saved_msr; |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 441 | if (kcb->kprobe_status == KPROBE_REENTER) |
| 442 | restore_previous_kprobe(kcb); |
| 443 | else |
| 444 | reset_current_kprobe(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 445 | preempt_enable_no_resched(); |
Prasanna S Panchamukhi | 50e21f2 | 2006-03-26 01:38:24 -0800 | [diff] [blame] | 446 | break; |
| 447 | case KPROBE_HIT_ACTIVE: |
| 448 | case KPROBE_HIT_SSDONE: |
| 449 | /* |
| 450 | * We increment the nmissed count for accounting, |
| 451 | * we can also use npre/npostfault count for accouting |
| 452 | * these specific fault cases. |
| 453 | */ |
| 454 | kprobes_inc_nmissed_count(cur); |
| 455 | |
| 456 | /* |
| 457 | * We come here because instructions in the pre/post |
| 458 | * handler caused the page_fault, this could happen |
| 459 | * if handler tries to access user space by |
| 460 | * copy_from_user(), get_user() etc. Let the |
| 461 | * user-specified handler try to fix it first. |
| 462 | */ |
| 463 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) |
| 464 | return 1; |
| 465 | |
| 466 | /* |
| 467 | * In case the user-specified fault handler returned |
| 468 | * zero, try to fix up. |
| 469 | */ |
| 470 | if ((entry = search_exception_tables(regs->nip)) != NULL) { |
| 471 | regs->nip = entry->fixup; |
| 472 | return 1; |
| 473 | } |
| 474 | |
| 475 | /* |
| 476 | * fixup_exception() could not handle it, |
| 477 | * Let do_page_fault() fix it. |
| 478 | */ |
| 479 | break; |
| 480 | default: |
| 481 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 482 | } |
| 483 | return 0; |
| 484 | } |
| 485 | |
| 486 | /* |
| 487 | * Wrapper routine to for handling exceptions. |
| 488 | */ |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 489 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 490 | unsigned long val, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 491 | { |
| 492 | struct die_args *args = (struct die_args *)data; |
| 493 | int ret = NOTIFY_DONE; |
| 494 | |
bibo,mao | 2326c77 | 2006-03-26 01:38:21 -0800 | [diff] [blame] | 495 | if (args->regs && user_mode(args->regs)) |
| 496 | return ret; |
| 497 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 498 | switch (val) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | case DIE_BPT: |
| 500 | if (kprobe_handler(args->regs)) |
| 501 | ret = NOTIFY_STOP; |
| 502 | break; |
| 503 | case DIE_SSTEP: |
| 504 | if (post_kprobe_handler(args->regs)) |
| 505 | ret = NOTIFY_STOP; |
| 506 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | default: |
| 508 | break; |
| 509 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 510 | return ret; |
| 511 | } |
| 512 | |
Michael Ellerman | 3d7e338 | 2007-07-19 01:48:11 -0700 | [diff] [blame] | 513 | #ifdef CONFIG_PPC64 |
| 514 | unsigned long arch_deref_entry_point(void *entry) |
| 515 | { |
Michael Ellerman | 80d267f | 2008-05-23 14:22:21 +1000 | [diff] [blame] | 516 | return ((func_descr_t *)entry)->entry; |
Michael Ellerman | 3d7e338 | 2007-07-19 01:48:11 -0700 | [diff] [blame] | 517 | } |
| 518 | #endif |
| 519 | |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 520 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | { |
| 522 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 523 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 524 | |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 525 | memcpy(&kcb->jprobe_saved_regs, regs, sizeof(struct pt_regs)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 526 | |
| 527 | /* setup return addr to the jprobe handler routine */ |
Michael Ellerman | 3d7e338 | 2007-07-19 01:48:11 -0700 | [diff] [blame] | 528 | regs->nip = arch_deref_entry_point(jp->entry); |
Kumar Gala | 8209003 | 2007-02-06 22:55:19 -0600 | [diff] [blame] | 529 | #ifdef CONFIG_PPC64 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 530 | regs->gpr[2] = (unsigned long)(((func_descr_t *)jp->entry)->toc); |
Kumar Gala | 8209003 | 2007-02-06 22:55:19 -0600 | [diff] [blame] | 531 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 532 | |
| 533 | return 1; |
| 534 | } |
| 535 | |
Ananth N Mavinakayanahalli | 66200ea | 2008-02-15 21:59:17 +1100 | [diff] [blame] | 536 | void __used __kprobes jprobe_return(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 537 | { |
| 538 | asm volatile("trap" ::: "memory"); |
| 539 | } |
| 540 | |
Ananth N Mavinakayanahalli | 66200ea | 2008-02-15 21:59:17 +1100 | [diff] [blame] | 541 | static void __used __kprobes jprobe_return_end(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 542 | { |
| 543 | }; |
| 544 | |
Prasanna S Panchamukhi | bb144a8 | 2005-09-06 15:19:29 -0700 | [diff] [blame] | 545 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 546 | { |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 547 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 548 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | /* |
| 550 | * FIXME - we should ideally be validating that we got here 'cos |
| 551 | * of the "trap" in jprobe_return() above, before restoring the |
| 552 | * saved regs... |
| 553 | */ |
Ananth N Mavinakayanahalli | 0dc036c | 2005-11-07 01:00:10 -0800 | [diff] [blame] | 554 | memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs)); |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 555 | preempt_enable_no_resched(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 556 | return 1; |
| 557 | } |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 558 | |
| 559 | static struct kprobe trampoline_p = { |
| 560 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
| 561 | .pre_handler = trampoline_probe_handler |
| 562 | }; |
| 563 | |
Rusty Lynch | 6772926 | 2005-07-05 18:54:50 -0700 | [diff] [blame] | 564 | int __init arch_init_kprobes(void) |
Rusty Lynch | 97f7943 | 2005-06-27 15:17:15 -0700 | [diff] [blame] | 565 | { |
| 566 | return register_kprobe(&trampoline_p); |
| 567 | } |
Ananth N Mavinakayanahalli | bf8f6e5b | 2007-05-08 00:34:16 -0700 | [diff] [blame] | 568 | |
| 569 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
| 570 | { |
| 571 | if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) |
| 572 | return 1; |
| 573 | |
| 574 | return 0; |
| 575 | } |