Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Kernel Probes (KProbes) |
| 3 | * arch/x86_64/kernel/kprobes.c |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
| 18 | * |
| 19 | * Copyright (C) IBM Corporation, 2002, 2004 |
| 20 | * |
| 21 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
| 22 | * Probes initial implementation ( includes contributions from |
| 23 | * Rusty Russell). |
| 24 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
| 25 | * interface to access function arguments. |
| 26 | * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi |
| 27 | * <prasanna@in.ibm.com> adapted for x86_64 |
| 28 | * 2005-Mar Roland McGrath <roland@redhat.com> |
| 29 | * Fixed to handle %rip-relative addressing mode correctly. |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 30 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> |
| 31 | * Added function return probes functionality |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | */ |
| 33 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | #include <linux/kprobes.h> |
| 35 | #include <linux/ptrace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 36 | #include <linux/string.h> |
| 37 | #include <linux/slab.h> |
| 38 | #include <linux/preempt.h> |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 39 | #include <linux/module.h> |
Christoph Hellwig | 1eeb66a | 2007-05-08 00:27:03 -0700 | [diff] [blame] | 40 | #include <linux/kdebug.h> |
Ananth N Mavinakayanahalli | 9ec4b1f | 2005-06-27 15:17:01 -0700 | [diff] [blame] | 41 | |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 42 | #include <asm/cacheflush.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | #include <asm/pgtable.h> |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 44 | #include <asm/uaccess.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 46 | void jprobe_return_end(void); |
Keshavamurthy Anil S | f709b12 | 2006-01-09 20:52:44 -0800 | [diff] [blame] | 47 | static void __kprobes arch_copy_kprobe(struct kprobe *p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 49 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
| 50 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | |
| 52 | /* |
| 53 | * returns non-zero if opcode modifies the interrupt flag. |
| 54 | */ |
Prasanna S Panchamukhi | 3b60211 | 2006-04-18 22:22:00 -0700 | [diff] [blame] | 55 | static __always_inline int is_IF_modifier(kprobe_opcode_t *insn) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | { |
| 57 | switch (*insn) { |
| 58 | case 0xfa: /* cli */ |
| 59 | case 0xfb: /* sti */ |
| 60 | case 0xcf: /* iret/iretd */ |
| 61 | case 0x9d: /* popf/popfd */ |
| 62 | return 1; |
| 63 | } |
| 64 | |
| 65 | if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf) |
| 66 | return 1; |
| 67 | return 0; |
| 68 | } |
| 69 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 70 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | { |
| 72 | /* insn: must be on special executable page on x86_64. */ |
Zhang, Yanmin | 2dd960d | 2005-09-30 11:59:20 -0700 | [diff] [blame] | 73 | p->ainsn.insn = get_insn_slot(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | if (!p->ainsn.insn) { |
| 75 | return -ENOMEM; |
| 76 | } |
Anil S Keshavamurthy | 49a2a1b | 2006-01-09 20:52:43 -0800 | [diff] [blame] | 77 | arch_copy_kprobe(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | return 0; |
| 79 | } |
| 80 | |
| 81 | /* |
| 82 | * Determine if the instruction uses the %rip-relative addressing mode. |
| 83 | * If it does, return the address of the 32-bit displacement word. |
| 84 | * If not, return null. |
| 85 | */ |
Prasanna S Panchamukhi | 3b60211 | 2006-04-18 22:22:00 -0700 | [diff] [blame] | 86 | static s32 __kprobes *is_riprel(u8 *insn) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 87 | { |
| 88 | #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ |
| 89 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ |
| 90 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ |
| 91 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ |
| 92 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ |
| 93 | << (row % 64)) |
| 94 | static const u64 onebyte_has_modrm[256 / 64] = { |
| 95 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 96 | /* ------------------------------- */ |
| 97 | W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */ |
| 98 | W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */ |
| 99 | W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */ |
| 100 | W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */ |
| 101 | W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */ |
| 102 | W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */ |
| 103 | W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */ |
| 104 | W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */ |
| 105 | W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */ |
| 106 | W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */ |
| 107 | W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */ |
| 108 | W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */ |
| 109 | W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */ |
| 110 | W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */ |
| 111 | W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */ |
| 112 | W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */ |
| 113 | /* ------------------------------- */ |
| 114 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 115 | }; |
| 116 | static const u64 twobyte_has_modrm[256 / 64] = { |
| 117 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 118 | /* ------------------------------- */ |
| 119 | W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */ |
| 120 | W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */ |
| 121 | W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */ |
| 122 | W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */ |
| 123 | W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */ |
| 124 | W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */ |
| 125 | W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */ |
| 126 | W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */ |
| 127 | W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */ |
| 128 | W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */ |
| 129 | W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */ |
| 130 | W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */ |
| 131 | W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */ |
| 132 | W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */ |
| 133 | W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */ |
| 134 | W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */ |
| 135 | /* ------------------------------- */ |
| 136 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 137 | }; |
| 138 | #undef W |
| 139 | int need_modrm; |
| 140 | |
| 141 | /* Skip legacy instruction prefixes. */ |
| 142 | while (1) { |
| 143 | switch (*insn) { |
| 144 | case 0x66: |
| 145 | case 0x67: |
| 146 | case 0x2e: |
| 147 | case 0x3e: |
| 148 | case 0x26: |
| 149 | case 0x64: |
| 150 | case 0x65: |
| 151 | case 0x36: |
| 152 | case 0xf0: |
| 153 | case 0xf3: |
| 154 | case 0xf2: |
| 155 | ++insn; |
| 156 | continue; |
| 157 | } |
| 158 | break; |
| 159 | } |
| 160 | |
| 161 | /* Skip REX instruction prefix. */ |
| 162 | if ((*insn & 0xf0) == 0x40) |
| 163 | ++insn; |
| 164 | |
| 165 | if (*insn == 0x0f) { /* Two-byte opcode. */ |
| 166 | ++insn; |
| 167 | need_modrm = test_bit(*insn, twobyte_has_modrm); |
| 168 | } else { /* One-byte opcode. */ |
| 169 | need_modrm = test_bit(*insn, onebyte_has_modrm); |
| 170 | } |
| 171 | |
| 172 | if (need_modrm) { |
| 173 | u8 modrm = *++insn; |
| 174 | if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */ |
| 175 | /* Displacement follows ModRM byte. */ |
| 176 | return (s32 *) ++insn; |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | /* No %rip-relative addressing mode here. */ |
| 181 | return NULL; |
| 182 | } |
| 183 | |
Keshavamurthy Anil S | f709b12 | 2006-01-09 20:52:44 -0800 | [diff] [blame] | 184 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 185 | { |
| 186 | s32 *ripdisp; |
| 187 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); |
| 188 | ripdisp = is_riprel(p->ainsn.insn); |
| 189 | if (ripdisp) { |
| 190 | /* |
| 191 | * The copied instruction uses the %rip-relative |
| 192 | * addressing mode. Adjust the displacement for the |
| 193 | * difference between the original location of this |
| 194 | * instruction and the location of the copy that will |
| 195 | * actually be run. The tricky bit here is making sure |
| 196 | * that the sign extension happens correctly in this |
| 197 | * calculation, since we need a signed 32-bit result to |
| 198 | * be sign-extended to 64 bits when it's added to the |
| 199 | * %rip value and yield the same 64-bit result that the |
| 200 | * sign-extension of the original signed 32-bit |
| 201 | * displacement would have given. |
| 202 | */ |
| 203 | s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn; |
| 204 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ |
| 205 | *ripdisp = disp; |
| 206 | } |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 207 | p->opcode = *p->addr; |
| 208 | } |
| 209 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 210 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 211 | { |
| 212 | *p->addr = BREAKPOINT_INSTRUCTION; |
| 213 | flush_icache_range((unsigned long) p->addr, |
| 214 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
| 215 | } |
| 216 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 217 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 218 | { |
| 219 | *p->addr = p->opcode; |
| 220 | flush_icache_range((unsigned long) p->addr, |
| 221 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 222 | } |
| 223 | |
Ananth N Mavinakayanahalli | 0498b63 | 2006-01-09 20:52:46 -0800 | [diff] [blame] | 224 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 225 | { |
Ingo Molnar | 7a7d1cf | 2006-03-23 03:00:35 -0800 | [diff] [blame] | 226 | mutex_lock(&kprobe_mutex); |
Masami Hiramatsu | b4c6c34 | 2006-12-06 20:38:11 -0800 | [diff] [blame] | 227 | free_insn_slot(p->ainsn.insn, 0); |
Ingo Molnar | 7a7d1cf | 2006-03-23 03:00:35 -0800 | [diff] [blame] | 228 | mutex_unlock(&kprobe_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 229 | } |
| 230 | |
Prasanna S Panchamukhi | 3b60211 | 2006-04-18 22:22:00 -0700 | [diff] [blame] | 231 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 232 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 233 | kcb->prev_kprobe.kp = kprobe_running(); |
| 234 | kcb->prev_kprobe.status = kcb->kprobe_status; |
| 235 | kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags; |
| 236 | kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 237 | } |
| 238 | |
Prasanna S Panchamukhi | 3b60211 | 2006-04-18 22:22:00 -0700 | [diff] [blame] | 239 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 240 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 241 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
| 242 | kcb->kprobe_status = kcb->prev_kprobe.status; |
| 243 | kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags; |
| 244 | kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 245 | } |
| 246 | |
Prasanna S Panchamukhi | 3b60211 | 2006-04-18 22:22:00 -0700 | [diff] [blame] | 247 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 248 | struct kprobe_ctlblk *kcb) |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 249 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 250 | __get_cpu_var(current_kprobe) = p; |
| 251 | kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 252 | = (regs->eflags & (TF_MASK | IF_MASK)); |
| 253 | if (is_IF_modifier(p->ainsn.insn)) |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 254 | kcb->kprobe_saved_rflags &= ~IF_MASK; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 255 | } |
| 256 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 257 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | { |
| 259 | regs->eflags |= TF_MASK; |
| 260 | regs->eflags &= ~IF_MASK; |
| 261 | /*single step inline if the instruction is an int3*/ |
| 262 | if (p->opcode == BREAKPOINT_INSTRUCTION) |
| 263 | regs->rip = (unsigned long)p->addr; |
| 264 | else |
| 265 | regs->rip = (unsigned long)p->ainsn.insn; |
| 266 | } |
| 267 | |
Ananth N Mavinakayanahalli | 991a51d | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 268 | /* Called with kretprobe_lock held */ |
Christoph Hellwig | 4c4308c | 2007-05-08 00:34:14 -0700 | [diff] [blame^] | 269 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 270 | struct pt_regs *regs) |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 271 | { |
| 272 | unsigned long *sara = (unsigned long *)regs->rsp; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 273 | |
Christoph Hellwig | 4c4308c | 2007-05-08 00:34:14 -0700 | [diff] [blame^] | 274 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
| 275 | /* Replace the return addr with trampoline addr */ |
| 276 | *sara = (unsigned long) &kretprobe_trampoline; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 277 | } |
| 278 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 279 | int __kprobes kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 280 | { |
| 281 | struct kprobe *p; |
| 282 | int ret = 0; |
| 283 | kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t)); |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 284 | struct kprobe_ctlblk *kcb; |
| 285 | |
| 286 | /* |
| 287 | * We don't want to be preempted for the entire |
| 288 | * duration of kprobe processing |
| 289 | */ |
| 290 | preempt_disable(); |
| 291 | kcb = get_kprobe_ctlblk(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 292 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 293 | /* Check we're not actually recursing */ |
| 294 | if (kprobe_running()) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | p = get_kprobe(addr); |
| 296 | if (p) { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 297 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
Keshavamurthy Anil S | deac66a | 2005-09-06 15:19:35 -0700 | [diff] [blame] | 298 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 299 | regs->eflags &= ~TF_MASK; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 300 | regs->eflags |= kcb->kprobe_saved_rflags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 301 | goto no_kprobe; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 302 | } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 303 | /* TODO: Provide re-entrancy from |
| 304 | * post_kprobes_handler() and avoid exception |
| 305 | * stack corruption while single-stepping on |
| 306 | * the instruction of the new probe. |
| 307 | */ |
| 308 | arch_disarm_kprobe(p); |
| 309 | regs->rip = (unsigned long)p->addr; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 310 | reset_current_kprobe(); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 311 | ret = 1; |
| 312 | } else { |
| 313 | /* We have reentered the kprobe_handler(), since |
| 314 | * another probe was hit while within the |
| 315 | * handler. We here save the original kprobe |
| 316 | * variables and just single step on instruction |
| 317 | * of the new probe without calling any user |
| 318 | * handlers. |
| 319 | */ |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 320 | save_previous_kprobe(kcb); |
| 321 | set_current_kprobe(p, regs, kcb); |
Keshavamurthy Anil S | bf8d5c5 | 2005-12-12 00:37:34 -0800 | [diff] [blame] | 322 | kprobes_inc_nmissed_count(p); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 323 | prepare_singlestep(p, regs); |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 324 | kcb->kprobe_status = KPROBE_REENTER; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 325 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 326 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 327 | } else { |
Keshavamurthy Anil S | eb3a729 | 2006-01-11 12:17:42 -0800 | [diff] [blame] | 328 | if (*addr != BREAKPOINT_INSTRUCTION) { |
| 329 | /* The breakpoint instruction was removed by |
| 330 | * another cpu right after we hit, no further |
| 331 | * handling of this interrupt is appropriate |
| 332 | */ |
| 333 | regs->rip = (unsigned long)addr; |
| 334 | ret = 1; |
| 335 | goto no_kprobe; |
| 336 | } |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 337 | p = __get_cpu_var(current_kprobe); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | if (p->break_handler && p->break_handler(p, regs)) { |
| 339 | goto ss_probe; |
| 340 | } |
| 341 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 342 | goto no_kprobe; |
| 343 | } |
| 344 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 345 | p = get_kprobe(addr); |
| 346 | if (!p) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 347 | if (*addr != BREAKPOINT_INSTRUCTION) { |
| 348 | /* |
| 349 | * The breakpoint instruction was removed right |
| 350 | * after we hit it. Another cpu has removed |
| 351 | * either a probepoint or a debugger breakpoint |
| 352 | * at this address. In either case, no further |
| 353 | * handling of this interrupt is appropriate. |
Jim Keniston | bce0649 | 2005-09-06 15:19:34 -0700 | [diff] [blame] | 354 | * Back up over the (now missing) int3 and run |
| 355 | * the original instruction. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 356 | */ |
Jim Keniston | bce0649 | 2005-09-06 15:19:34 -0700 | [diff] [blame] | 357 | regs->rip = (unsigned long)addr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 358 | ret = 1; |
| 359 | } |
| 360 | /* Not one of ours: let kernel handle it */ |
| 361 | goto no_kprobe; |
| 362 | } |
| 363 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 364 | set_current_kprobe(p, regs, kcb); |
| 365 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 366 | |
| 367 | if (p->pre_handler && p->pre_handler(p, regs)) |
| 368 | /* handler has already set things up, so skip ss setup */ |
| 369 | return 1; |
| 370 | |
| 371 | ss_probe: |
| 372 | prepare_singlestep(p, regs); |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 373 | kcb->kprobe_status = KPROBE_HIT_SS; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 374 | return 1; |
| 375 | |
| 376 | no_kprobe: |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 377 | preempt_enable_no_resched(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 378 | return ret; |
| 379 | } |
| 380 | |
| 381 | /* |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 382 | * For function-return probes, init_kprobes() establishes a probepoint |
| 383 | * here. When a retprobed function returns, this probe is hit and |
| 384 | * trampoline_probe_handler() runs, calling the kretprobe's handler. |
| 385 | */ |
| 386 | void kretprobe_trampoline_holder(void) |
| 387 | { |
| 388 | asm volatile ( ".global kretprobe_trampoline\n" |
| 389 | "kretprobe_trampoline: \n" |
| 390 | "nop\n"); |
| 391 | } |
| 392 | |
| 393 | /* |
| 394 | * Called when we hit the probe point at kretprobe_trampoline |
| 395 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 396 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 397 | { |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 398 | struct kretprobe_instance *ri = NULL; |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 399 | struct hlist_head *head, empty_rp; |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 400 | struct hlist_node *node, *tmp; |
Ananth N Mavinakayanahalli | 991a51d | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 401 | unsigned long flags, orig_ret_address = 0; |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 402 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 403 | |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 404 | INIT_HLIST_HEAD(&empty_rp); |
Ananth N Mavinakayanahalli | 991a51d | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 405 | spin_lock_irqsave(&kretprobe_lock, flags); |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 406 | head = kretprobe_inst_table_head(current); |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 407 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 408 | /* |
| 409 | * It is possible to have multiple instances associated with a given |
| 410 | * task either because an multiple functions in the call path |
| 411 | * have a return probe installed on them, and/or more then one return |
| 412 | * return probe was registered for a target function. |
| 413 | * |
| 414 | * We can handle this because: |
| 415 | * - instances are always inserted at the head of the list |
| 416 | * - when multiple return probes are registered for the same |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 417 | * function, the first instance's ret_addr will point to the |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 418 | * real return address, and all the rest will point to |
| 419 | * kretprobe_trampoline |
| 420 | */ |
| 421 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 422 | if (ri->task != current) |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 423 | /* another task is sharing our hash bucket */ |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 424 | continue; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 425 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 426 | if (ri->rp && ri->rp->handler) |
| 427 | ri->rp->handler(ri, regs); |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 428 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 429 | orig_ret_address = (unsigned long)ri->ret_addr; |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 430 | recycle_rp_inst(ri, &empty_rp); |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 431 | |
| 432 | if (orig_ret_address != trampoline_address) |
| 433 | /* |
| 434 | * This is the real return address. Any other |
| 435 | * instances associated with this task are for |
| 436 | * other calls deeper on the call stack |
| 437 | */ |
| 438 | break; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 439 | } |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 440 | |
Ananth N Mavinakayanahalli | 0f95b7f | 2007-05-08 00:28:27 -0700 | [diff] [blame] | 441 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 442 | regs->rip = orig_ret_address; |
| 443 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 444 | reset_current_kprobe(); |
Ananth N Mavinakayanahalli | 991a51d | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 445 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 446 | preempt_enable_no_resched(); |
| 447 | |
bibo,mao | 99219a3 | 2006-10-02 02:17:35 -0700 | [diff] [blame] | 448 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
| 449 | hlist_del(&ri->hlist); |
| 450 | kfree(ri); |
| 451 | } |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 452 | /* |
| 453 | * By returning a non-zero value, we are telling |
| 454 | * kprobe_handler() that we don't want the post_handler |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 455 | * to run (and have re-enabled preemption) |
bibo,mao | 62c27be | 2006-10-02 02:17:33 -0700 | [diff] [blame] | 456 | */ |
| 457 | return 1; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 458 | } |
| 459 | |
| 460 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 461 | * Called after single-stepping. p->addr is the address of the |
| 462 | * instruction whose first byte has been replaced by the "int 3" |
| 463 | * instruction. To avoid the SMP problems that can occur when we |
| 464 | * temporarily put back the original opcode to single-step, we |
| 465 | * single-stepped a copy of the instruction. The address of this |
| 466 | * copy is p->ainsn.insn. |
| 467 | * |
| 468 | * This function prepares to return from the post-single-step |
| 469 | * interrupt. We have to fix up the stack as follows: |
| 470 | * |
| 471 | * 0) Except in the case of absolute or indirect jump or call instructions, |
| 472 | * the new rip is relative to the copied instruction. We need to make |
| 473 | * it relative to the original instruction. |
| 474 | * |
| 475 | * 1) If the single-stepped instruction was pushfl, then the TF and IF |
| 476 | * flags are set in the just-pushed eflags, and may need to be cleared. |
| 477 | * |
| 478 | * 2) If the single-stepped instruction was a call, the return address |
| 479 | * that is atop the stack is the address following the copied instruction. |
| 480 | * We need to make it the address following the original instruction. |
| 481 | */ |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 482 | static void __kprobes resume_execution(struct kprobe *p, |
| 483 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 484 | { |
| 485 | unsigned long *tos = (unsigned long *)regs->rsp; |
| 486 | unsigned long next_rip = 0; |
| 487 | unsigned long copy_rip = (unsigned long)p->ainsn.insn; |
| 488 | unsigned long orig_rip = (unsigned long)p->addr; |
| 489 | kprobe_opcode_t *insn = p->ainsn.insn; |
| 490 | |
| 491 | /*skip the REX prefix*/ |
| 492 | if (*insn >= 0x40 && *insn <= 0x4f) |
| 493 | insn++; |
| 494 | |
| 495 | switch (*insn) { |
| 496 | case 0x9c: /* pushfl */ |
| 497 | *tos &= ~(TF_MASK | IF_MASK); |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 498 | *tos |= kcb->kprobe_old_rflags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 499 | break; |
Prasanna S Panchamukhi | 0b9e2ca | 2005-05-05 16:15:40 -0700 | [diff] [blame] | 500 | case 0xc3: /* ret/lret */ |
| 501 | case 0xcb: |
| 502 | case 0xc2: |
| 503 | case 0xca: |
| 504 | regs->eflags &= ~TF_MASK; |
| 505 | /* rip is already adjusted, no more changes required*/ |
| 506 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | case 0xe8: /* call relative - Fix return addr */ |
| 508 | *tos = orig_rip + (*tos - copy_rip); |
| 509 | break; |
| 510 | case 0xff: |
Satoshi Oshima | dc49e34 | 2006-05-20 15:00:21 -0700 | [diff] [blame] | 511 | if ((insn[1] & 0x30) == 0x10) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 512 | /* call absolute, indirect */ |
| 513 | /* Fix return addr; rip is correct. */ |
| 514 | next_rip = regs->rip; |
| 515 | *tos = orig_rip + (*tos - copy_rip); |
Satoshi Oshima | dc49e34 | 2006-05-20 15:00:21 -0700 | [diff] [blame] | 516 | } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
| 517 | ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 518 | /* rip is correct. */ |
| 519 | next_rip = regs->rip; |
| 520 | } |
| 521 | break; |
| 522 | case 0xea: /* jmp absolute -- rip is correct */ |
| 523 | next_rip = regs->rip; |
| 524 | break; |
| 525 | default: |
| 526 | break; |
| 527 | } |
| 528 | |
| 529 | regs->eflags &= ~TF_MASK; |
| 530 | if (next_rip) { |
| 531 | regs->rip = next_rip; |
| 532 | } else { |
| 533 | regs->rip = orig_rip + (regs->rip - copy_rip); |
| 534 | } |
| 535 | } |
| 536 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 537 | int __kprobes post_kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 539 | struct kprobe *cur = kprobe_running(); |
| 540 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 541 | |
| 542 | if (!cur) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 543 | return 0; |
| 544 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 545 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
| 546 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
| 547 | cur->post_handler(cur, regs, 0); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 548 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 549 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 550 | resume_execution(cur, regs, kcb); |
| 551 | regs->eflags |= kcb->kprobe_saved_rflags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 552 | |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 553 | /* Restore the original saved kprobes variables and continue. */ |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 554 | if (kcb->kprobe_status == KPROBE_REENTER) { |
| 555 | restore_previous_kprobe(kcb); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 556 | goto out; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 557 | } |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 558 | reset_current_kprobe(); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 559 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 560 | preempt_enable_no_resched(); |
| 561 | |
| 562 | /* |
| 563 | * if somebody else is singlestepping across a probe point, eflags |
| 564 | * will have TF set, in which case, continue the remaining processing |
| 565 | * of do_debug, as if this is not a probe hit. |
| 566 | */ |
| 567 | if (regs->eflags & TF_MASK) |
| 568 | return 0; |
| 569 | |
| 570 | return 1; |
| 571 | } |
| 572 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 573 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 574 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 575 | struct kprobe *cur = kprobe_running(); |
| 576 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 577 | const struct exception_table_entry *fixup; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 578 | |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 579 | switch(kcb->kprobe_status) { |
| 580 | case KPROBE_HIT_SS: |
| 581 | case KPROBE_REENTER: |
| 582 | /* |
| 583 | * We are here because the instruction being single |
| 584 | * stepped caused a page fault. We reset the current |
| 585 | * kprobe and the rip points back to the probe address |
| 586 | * and allow the page fault handler to continue as a |
| 587 | * normal page fault. |
| 588 | */ |
| 589 | regs->rip = (unsigned long)cur->addr; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 590 | regs->eflags |= kcb->kprobe_old_rflags; |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 591 | if (kcb->kprobe_status == KPROBE_REENTER) |
| 592 | restore_previous_kprobe(kcb); |
| 593 | else |
| 594 | reset_current_kprobe(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 595 | preempt_enable_no_resched(); |
Prasanna S Panchamukhi | c28f896 | 2006-03-26 01:38:23 -0800 | [diff] [blame] | 596 | break; |
| 597 | case KPROBE_HIT_ACTIVE: |
| 598 | case KPROBE_HIT_SSDONE: |
| 599 | /* |
| 600 | * We increment the nmissed count for accounting, |
| 601 | * we can also use npre/npostfault count for accouting |
| 602 | * these specific fault cases. |
| 603 | */ |
| 604 | kprobes_inc_nmissed_count(cur); |
| 605 | |
| 606 | /* |
| 607 | * We come here because instructions in the pre/post |
| 608 | * handler caused the page_fault, this could happen |
| 609 | * if handler tries to access user space by |
| 610 | * copy_from_user(), get_user() etc. Let the |
| 611 | * user-specified handler try to fix it first. |
| 612 | */ |
| 613 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) |
| 614 | return 1; |
| 615 | |
| 616 | /* |
| 617 | * In case the user-specified fault handler returned |
| 618 | * zero, try to fix up. |
| 619 | */ |
| 620 | fixup = search_exception_tables(regs->rip); |
| 621 | if (fixup) { |
| 622 | regs->rip = fixup->fixup; |
| 623 | return 1; |
| 624 | } |
| 625 | |
| 626 | /* |
| 627 | * fixup() could not handle it, |
| 628 | * Let do_page_fault() fix it. |
| 629 | */ |
| 630 | break; |
| 631 | default: |
| 632 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 633 | } |
| 634 | return 0; |
| 635 | } |
| 636 | |
| 637 | /* |
| 638 | * Wrapper routine for handling exceptions. |
| 639 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 640 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 641 | unsigned long val, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 642 | { |
| 643 | struct die_args *args = (struct die_args *)data; |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 644 | int ret = NOTIFY_DONE; |
| 645 | |
bibo,mao | 2326c77 | 2006-03-26 01:38:21 -0800 | [diff] [blame] | 646 | if (args->regs && user_mode(args->regs)) |
| 647 | return ret; |
| 648 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 649 | switch (val) { |
| 650 | case DIE_INT3: |
| 651 | if (kprobe_handler(args->regs)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 652 | ret = NOTIFY_STOP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 653 | break; |
| 654 | case DIE_DEBUG: |
| 655 | if (post_kprobe_handler(args->regs)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 656 | ret = NOTIFY_STOP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 657 | break; |
| 658 | case DIE_GPF: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 659 | case DIE_PAGE_FAULT: |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 660 | /* kprobe_running() needs smp_processor_id() */ |
| 661 | preempt_disable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 662 | if (kprobe_running() && |
| 663 | kprobe_fault_handler(args->regs, args->trapnr)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 664 | ret = NOTIFY_STOP; |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 665 | preempt_enable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 666 | break; |
| 667 | default: |
| 668 | break; |
| 669 | } |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame] | 670 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 671 | } |
| 672 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 673 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 674 | { |
| 675 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 676 | unsigned long addr; |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 677 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 678 | |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 679 | kcb->jprobe_saved_regs = *regs; |
| 680 | kcb->jprobe_saved_rsp = (long *) regs->rsp; |
| 681 | addr = (unsigned long)(kcb->jprobe_saved_rsp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 682 | /* |
| 683 | * As Linus pointed out, gcc assumes that the callee |
| 684 | * owns the argument space and could overwrite it, e.g. |
| 685 | * tailcall optimization. So, to be absolutely safe |
| 686 | * we also save and restore enough stack bytes to cover |
| 687 | * the argument area. |
| 688 | */ |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 689 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
| 690 | MIN_STACK_SIZE(addr)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 691 | regs->eflags &= ~IF_MASK; |
| 692 | regs->rip = (unsigned long)(jp->entry); |
| 693 | return 1; |
| 694 | } |
| 695 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 696 | void __kprobes jprobe_return(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 697 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 698 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| 699 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 700 | asm volatile (" xchg %%rbx,%%rsp \n" |
| 701 | " int3 \n" |
| 702 | " .globl jprobe_return_end \n" |
| 703 | " jprobe_return_end: \n" |
| 704 | " nop \n"::"b" |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 705 | (kcb->jprobe_saved_rsp):"memory"); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 706 | } |
| 707 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 708 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 709 | { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 710 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 711 | u8 *addr = (u8 *) (regs->rip - 1); |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 712 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 713 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 714 | |
| 715 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 716 | if ((long *)regs->rsp != kcb->jprobe_saved_rsp) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 717 | struct pt_regs *saved_regs = |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 718 | container_of(kcb->jprobe_saved_rsp, |
| 719 | struct pt_regs, rsp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 720 | printk("current rsp %p does not match saved rsp %p\n", |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 721 | (long *)regs->rsp, kcb->jprobe_saved_rsp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 722 | printk("Saved registers for jprobe %p\n", jp); |
| 723 | show_registers(saved_regs); |
| 724 | printk("Current registers\n"); |
| 725 | show_registers(regs); |
| 726 | BUG(); |
| 727 | } |
Ananth N Mavinakayanahalli | e7a510f | 2005-11-07 01:00:12 -0800 | [diff] [blame] | 728 | *regs = kcb->jprobe_saved_regs; |
| 729 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 730 | MIN_STACK_SIZE(stack_addr)); |
Ananth N Mavinakayanahalli | d217d54 | 2005-11-07 01:00:14 -0800 | [diff] [blame] | 731 | preempt_enable_no_resched(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 732 | return 1; |
| 733 | } |
| 734 | return 0; |
| 735 | } |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 736 | |
| 737 | static struct kprobe trampoline_p = { |
| 738 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
| 739 | .pre_handler = trampoline_probe_handler |
| 740 | }; |
| 741 | |
Rusty Lynch | 6772926 | 2005-07-05 18:54:50 -0700 | [diff] [blame] | 742 | int __init arch_init_kprobes(void) |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 743 | { |
| 744 | return register_kprobe(&trampoline_p); |
| 745 | } |