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 | |
| 34 | #include <linux/config.h> |
| 35 | #include <linux/kprobes.h> |
| 36 | #include <linux/ptrace.h> |
| 37 | #include <linux/spinlock.h> |
| 38 | #include <linux/string.h> |
| 39 | #include <linux/slab.h> |
| 40 | #include <linux/preempt.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> |
| 44 | #include <asm/kdebug.h> |
| 45 | |
| 46 | static DECLARE_MUTEX(kprobe_mutex); |
| 47 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | static struct kprobe *current_kprobe; |
| 49 | static unsigned long kprobe_status, kprobe_old_rflags, kprobe_saved_rflags; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 50 | static struct kprobe *kprobe_prev; |
| 51 | static unsigned long kprobe_status_prev, kprobe_old_rflags_prev, kprobe_saved_rflags_prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 52 | static struct pt_regs jprobe_saved_regs; |
| 53 | static long *jprobe_saved_rsp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | void jprobe_return_end(void); |
| 55 | |
| 56 | /* copy of the kernel stack at the probe fire time */ |
| 57 | static kprobe_opcode_t jprobes_stack[MAX_STACK_SIZE]; |
| 58 | |
| 59 | /* |
| 60 | * returns non-zero if opcode modifies the interrupt flag. |
| 61 | */ |
| 62 | static inline int is_IF_modifier(kprobe_opcode_t *insn) |
| 63 | { |
| 64 | switch (*insn) { |
| 65 | case 0xfa: /* cli */ |
| 66 | case 0xfb: /* sti */ |
| 67 | case 0xcf: /* iret/iretd */ |
| 68 | case 0x9d: /* popf/popfd */ |
| 69 | return 1; |
| 70 | } |
| 71 | |
| 72 | if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf) |
| 73 | return 1; |
| 74 | return 0; |
| 75 | } |
| 76 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 77 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 78 | { |
| 79 | /* insn: must be on special executable page on x86_64. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | down(&kprobe_mutex); |
Zhang, Yanmin | 2dd960d | 2005-09-30 11:59:20 -0700 | [diff] [blame] | 81 | p->ainsn.insn = get_insn_slot(); |
| 82 | up(&kprobe_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | if (!p->ainsn.insn) { |
| 84 | return -ENOMEM; |
| 85 | } |
| 86 | return 0; |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * Determine if the instruction uses the %rip-relative addressing mode. |
| 91 | * If it does, return the address of the 32-bit displacement word. |
| 92 | * If not, return null. |
| 93 | */ |
| 94 | static inline s32 *is_riprel(u8 *insn) |
| 95 | { |
| 96 | #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ |
| 97 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ |
| 98 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ |
| 99 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ |
| 100 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ |
| 101 | << (row % 64)) |
| 102 | static const u64 onebyte_has_modrm[256 / 64] = { |
| 103 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 104 | /* ------------------------------- */ |
| 105 | W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */ |
| 106 | W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */ |
| 107 | W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */ |
| 108 | W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */ |
| 109 | W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */ |
| 110 | W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */ |
| 111 | W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */ |
| 112 | W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */ |
| 113 | W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */ |
| 114 | W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */ |
| 115 | W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */ |
| 116 | W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */ |
| 117 | W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */ |
| 118 | W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */ |
| 119 | W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */ |
| 120 | W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */ |
| 121 | /* ------------------------------- */ |
| 122 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 123 | }; |
| 124 | static const u64 twobyte_has_modrm[256 / 64] = { |
| 125 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 126 | /* ------------------------------- */ |
| 127 | W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */ |
| 128 | W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */ |
| 129 | W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */ |
| 130 | W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */ |
| 131 | W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */ |
| 132 | W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */ |
| 133 | W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */ |
| 134 | W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */ |
| 135 | W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */ |
| 136 | W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */ |
| 137 | W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */ |
| 138 | W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */ |
| 139 | W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */ |
| 140 | W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */ |
| 141 | W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */ |
| 142 | W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */ |
| 143 | /* ------------------------------- */ |
| 144 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
| 145 | }; |
| 146 | #undef W |
| 147 | int need_modrm; |
| 148 | |
| 149 | /* Skip legacy instruction prefixes. */ |
| 150 | while (1) { |
| 151 | switch (*insn) { |
| 152 | case 0x66: |
| 153 | case 0x67: |
| 154 | case 0x2e: |
| 155 | case 0x3e: |
| 156 | case 0x26: |
| 157 | case 0x64: |
| 158 | case 0x65: |
| 159 | case 0x36: |
| 160 | case 0xf0: |
| 161 | case 0xf3: |
| 162 | case 0xf2: |
| 163 | ++insn; |
| 164 | continue; |
| 165 | } |
| 166 | break; |
| 167 | } |
| 168 | |
| 169 | /* Skip REX instruction prefix. */ |
| 170 | if ((*insn & 0xf0) == 0x40) |
| 171 | ++insn; |
| 172 | |
| 173 | if (*insn == 0x0f) { /* Two-byte opcode. */ |
| 174 | ++insn; |
| 175 | need_modrm = test_bit(*insn, twobyte_has_modrm); |
| 176 | } else { /* One-byte opcode. */ |
| 177 | need_modrm = test_bit(*insn, onebyte_has_modrm); |
| 178 | } |
| 179 | |
| 180 | if (need_modrm) { |
| 181 | u8 modrm = *++insn; |
| 182 | if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */ |
| 183 | /* Displacement follows ModRM byte. */ |
| 184 | return (s32 *) ++insn; |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /* No %rip-relative addressing mode here. */ |
| 189 | return NULL; |
| 190 | } |
| 191 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 192 | void __kprobes arch_copy_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | { |
| 194 | s32 *ripdisp; |
| 195 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); |
| 196 | ripdisp = is_riprel(p->ainsn.insn); |
| 197 | if (ripdisp) { |
| 198 | /* |
| 199 | * The copied instruction uses the %rip-relative |
| 200 | * addressing mode. Adjust the displacement for the |
| 201 | * difference between the original location of this |
| 202 | * instruction and the location of the copy that will |
| 203 | * actually be run. The tricky bit here is making sure |
| 204 | * that the sign extension happens correctly in this |
| 205 | * calculation, since we need a signed 32-bit result to |
| 206 | * be sign-extended to 64 bits when it's added to the |
| 207 | * %rip value and yield the same 64-bit result that the |
| 208 | * sign-extension of the original signed 32-bit |
| 209 | * displacement would have given. |
| 210 | */ |
| 211 | s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn; |
| 212 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ |
| 213 | *ripdisp = disp; |
| 214 | } |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 215 | p->opcode = *p->addr; |
| 216 | } |
| 217 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 218 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 219 | { |
| 220 | *p->addr = BREAKPOINT_INSTRUCTION; |
| 221 | flush_icache_range((unsigned long) p->addr, |
| 222 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
| 223 | } |
| 224 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 225 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
Rusty Lynch | 7e1048b | 2005-06-23 00:09:25 -0700 | [diff] [blame] | 226 | { |
| 227 | *p->addr = p->opcode; |
| 228 | flush_icache_range((unsigned long) p->addr, |
| 229 | (unsigned long) p->addr + sizeof(kprobe_opcode_t)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 230 | } |
| 231 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 232 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 234 | down(&kprobe_mutex); |
Zhang, Yanmin | 2dd960d | 2005-09-30 11:59:20 -0700 | [diff] [blame] | 235 | free_insn_slot(p->ainsn.insn); |
| 236 | up(&kprobe_mutex); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | } |
| 238 | |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 239 | static inline void save_previous_kprobe(void) |
| 240 | { |
| 241 | kprobe_prev = current_kprobe; |
| 242 | kprobe_status_prev = kprobe_status; |
| 243 | kprobe_old_rflags_prev = kprobe_old_rflags; |
| 244 | kprobe_saved_rflags_prev = kprobe_saved_rflags; |
| 245 | } |
| 246 | |
| 247 | static inline void restore_previous_kprobe(void) |
| 248 | { |
| 249 | current_kprobe = kprobe_prev; |
| 250 | kprobe_status = kprobe_status_prev; |
| 251 | kprobe_old_rflags = kprobe_old_rflags_prev; |
| 252 | kprobe_saved_rflags = kprobe_saved_rflags_prev; |
| 253 | } |
| 254 | |
| 255 | static inline void set_current_kprobe(struct kprobe *p, struct pt_regs *regs) |
| 256 | { |
| 257 | current_kprobe = p; |
| 258 | kprobe_saved_rflags = kprobe_old_rflags |
| 259 | = (regs->eflags & (TF_MASK | IF_MASK)); |
| 260 | if (is_IF_modifier(p->ainsn.insn)) |
| 261 | kprobe_saved_rflags &= ~IF_MASK; |
| 262 | } |
| 263 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 264 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 265 | { |
| 266 | regs->eflags |= TF_MASK; |
| 267 | regs->eflags &= ~IF_MASK; |
| 268 | /*single step inline if the instruction is an int3*/ |
| 269 | if (p->opcode == BREAKPOINT_INSTRUCTION) |
| 270 | regs->rip = (unsigned long)p->addr; |
| 271 | else |
| 272 | regs->rip = (unsigned long)p->ainsn.insn; |
| 273 | } |
| 274 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 275 | void __kprobes arch_prepare_kretprobe(struct kretprobe *rp, |
| 276 | struct pt_regs *regs) |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 277 | { |
| 278 | unsigned long *sara = (unsigned long *)regs->rsp; |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 279 | struct kretprobe_instance *ri; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 280 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 281 | if ((ri = get_free_rp_inst(rp)) != NULL) { |
| 282 | ri->rp = rp; |
| 283 | ri->task = current; |
| 284 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 285 | |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 286 | /* Replace the return addr with trampoline addr */ |
| 287 | *sara = (unsigned long) &kretprobe_trampoline; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 288 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 289 | add_rp_inst(ri); |
| 290 | } else { |
| 291 | rp->nmissed++; |
| 292 | } |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 293 | } |
| 294 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | /* |
| 296 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they |
| 297 | * remain disabled thorough out this function. |
| 298 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 299 | int __kprobes kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 300 | { |
| 301 | struct kprobe *p; |
| 302 | int ret = 0; |
| 303 | kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t)); |
| 304 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 305 | /* Check we're not actually recursing */ |
| 306 | if (kprobe_running()) { |
| 307 | /* We *are* holding lock here, so this is safe. |
| 308 | Disarm the probe we just hit, and ignore it. */ |
| 309 | p = get_kprobe(addr); |
| 310 | if (p) { |
Keshavamurthy Anil S | deac66a | 2005-09-06 15:19:35 -0700 | [diff] [blame] | 311 | if (kprobe_status == KPROBE_HIT_SS && |
| 312 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 313 | regs->eflags &= ~TF_MASK; |
| 314 | regs->eflags |= kprobe_saved_rflags; |
| 315 | unlock_kprobes(); |
| 316 | goto no_kprobe; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 317 | } else if (kprobe_status == KPROBE_HIT_SSDONE) { |
| 318 | /* TODO: Provide re-entrancy from |
| 319 | * post_kprobes_handler() and avoid exception |
| 320 | * stack corruption while single-stepping on |
| 321 | * the instruction of the new probe. |
| 322 | */ |
| 323 | arch_disarm_kprobe(p); |
| 324 | regs->rip = (unsigned long)p->addr; |
| 325 | ret = 1; |
| 326 | } else { |
| 327 | /* We have reentered the kprobe_handler(), since |
| 328 | * another probe was hit while within the |
| 329 | * handler. We here save the original kprobe |
| 330 | * variables and just single step on instruction |
| 331 | * of the new probe without calling any user |
| 332 | * handlers. |
| 333 | */ |
| 334 | save_previous_kprobe(); |
| 335 | set_current_kprobe(p, regs); |
| 336 | p->nmissed++; |
| 337 | prepare_singlestep(p, regs); |
| 338 | kprobe_status = KPROBE_REENTER; |
| 339 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 340 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 341 | } else { |
| 342 | p = current_kprobe; |
| 343 | if (p->break_handler && p->break_handler(p, regs)) { |
| 344 | goto ss_probe; |
| 345 | } |
| 346 | } |
| 347 | /* If it's not ours, can't be delete race, (we hold lock). */ |
| 348 | goto no_kprobe; |
| 349 | } |
| 350 | |
| 351 | lock_kprobes(); |
| 352 | p = get_kprobe(addr); |
| 353 | if (!p) { |
| 354 | unlock_kprobes(); |
| 355 | if (*addr != BREAKPOINT_INSTRUCTION) { |
| 356 | /* |
| 357 | * The breakpoint instruction was removed right |
| 358 | * after we hit it. Another cpu has removed |
| 359 | * either a probepoint or a debugger breakpoint |
| 360 | * at this address. In either case, no further |
| 361 | * handling of this interrupt is appropriate. |
Jim Keniston | bce0649 | 2005-09-06 15:19:34 -0700 | [diff] [blame] | 362 | * Back up over the (now missing) int3 and run |
| 363 | * the original instruction. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 364 | */ |
Jim Keniston | bce0649 | 2005-09-06 15:19:34 -0700 | [diff] [blame] | 365 | regs->rip = (unsigned long)addr; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 366 | ret = 1; |
| 367 | } |
| 368 | /* Not one of ours: let kernel handle it */ |
| 369 | goto no_kprobe; |
| 370 | } |
| 371 | |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 372 | /* |
| 373 | * This preempt_disable() matches the preempt_enable_no_resched() |
| 374 | * in post_kprobe_handler() |
| 375 | */ |
| 376 | preempt_disable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 377 | kprobe_status = KPROBE_HIT_ACTIVE; |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 378 | set_current_kprobe(p, regs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 379 | |
| 380 | if (p->pre_handler && p->pre_handler(p, regs)) |
| 381 | /* handler has already set things up, so skip ss setup */ |
| 382 | return 1; |
| 383 | |
| 384 | ss_probe: |
| 385 | prepare_singlestep(p, regs); |
| 386 | kprobe_status = KPROBE_HIT_SS; |
| 387 | return 1; |
| 388 | |
| 389 | no_kprobe: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 390 | return ret; |
| 391 | } |
| 392 | |
| 393 | /* |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 394 | * For function-return probes, init_kprobes() establishes a probepoint |
| 395 | * here. When a retprobed function returns, this probe is hit and |
| 396 | * trampoline_probe_handler() runs, calling the kretprobe's handler. |
| 397 | */ |
| 398 | void kretprobe_trampoline_holder(void) |
| 399 | { |
| 400 | asm volatile ( ".global kretprobe_trampoline\n" |
| 401 | "kretprobe_trampoline: \n" |
| 402 | "nop\n"); |
| 403 | } |
| 404 | |
| 405 | /* |
| 406 | * Called when we hit the probe point at kretprobe_trampoline |
| 407 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 408 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 409 | { |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 410 | struct kretprobe_instance *ri = NULL; |
| 411 | struct hlist_head *head; |
| 412 | struct hlist_node *node, *tmp; |
| 413 | unsigned long orig_ret_address = 0; |
| 414 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 415 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 416 | head = kretprobe_inst_table_head(current); |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 417 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 418 | /* |
| 419 | * It is possible to have multiple instances associated with a given |
| 420 | * task either because an multiple functions in the call path |
| 421 | * have a return probe installed on them, and/or more then one return |
| 422 | * return probe was registered for a target function. |
| 423 | * |
| 424 | * We can handle this because: |
| 425 | * - instances are always inserted at the head of the list |
| 426 | * - when multiple return probes are registered for the same |
| 427 | * function, the first instance's ret_addr will point to the |
| 428 | * real return address, and all the rest will point to |
| 429 | * kretprobe_trampoline |
| 430 | */ |
| 431 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { |
| 432 | if (ri->task != current) |
| 433 | /* another task is sharing our hash bucket */ |
| 434 | continue; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 435 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 436 | if (ri->rp && ri->rp->handler) |
| 437 | ri->rp->handler(ri, regs); |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 438 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 439 | orig_ret_address = (unsigned long)ri->ret_addr; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 440 | recycle_rp_inst(ri); |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 441 | |
| 442 | if (orig_ret_address != trampoline_address) |
| 443 | /* |
| 444 | * This is the real return address. Any other |
| 445 | * instances associated with this task are for |
| 446 | * other calls deeper on the call stack |
| 447 | */ |
| 448 | break; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 449 | } |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 450 | |
| 451 | BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address)); |
| 452 | regs->rip = orig_ret_address; |
| 453 | |
| 454 | unlock_kprobes(); |
| 455 | preempt_enable_no_resched(); |
| 456 | |
| 457 | /* |
| 458 | * By returning a non-zero value, we are telling |
| 459 | * kprobe_handler() that we have handled unlocking |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 460 | * and re-enabling preemption |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 461 | */ |
| 462 | return 1; |
Rusty Lynch | 73649da | 2005-06-23 00:09:23 -0700 | [diff] [blame] | 463 | } |
| 464 | |
| 465 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 466 | * Called after single-stepping. p->addr is the address of the |
| 467 | * instruction whose first byte has been replaced by the "int 3" |
| 468 | * instruction. To avoid the SMP problems that can occur when we |
| 469 | * temporarily put back the original opcode to single-step, we |
| 470 | * single-stepped a copy of the instruction. The address of this |
| 471 | * copy is p->ainsn.insn. |
| 472 | * |
| 473 | * This function prepares to return from the post-single-step |
| 474 | * interrupt. We have to fix up the stack as follows: |
| 475 | * |
| 476 | * 0) Except in the case of absolute or indirect jump or call instructions, |
| 477 | * the new rip is relative to the copied instruction. We need to make |
| 478 | * it relative to the original instruction. |
| 479 | * |
| 480 | * 1) If the single-stepped instruction was pushfl, then the TF and IF |
| 481 | * flags are set in the just-pushed eflags, and may need to be cleared. |
| 482 | * |
| 483 | * 2) If the single-stepped instruction was a call, the return address |
| 484 | * that is atop the stack is the address following the copied instruction. |
| 485 | * We need to make it the address following the original instruction. |
| 486 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 487 | static void __kprobes resume_execution(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 488 | { |
| 489 | unsigned long *tos = (unsigned long *)regs->rsp; |
| 490 | unsigned long next_rip = 0; |
| 491 | unsigned long copy_rip = (unsigned long)p->ainsn.insn; |
| 492 | unsigned long orig_rip = (unsigned long)p->addr; |
| 493 | kprobe_opcode_t *insn = p->ainsn.insn; |
| 494 | |
| 495 | /*skip the REX prefix*/ |
| 496 | if (*insn >= 0x40 && *insn <= 0x4f) |
| 497 | insn++; |
| 498 | |
| 499 | switch (*insn) { |
| 500 | case 0x9c: /* pushfl */ |
| 501 | *tos &= ~(TF_MASK | IF_MASK); |
| 502 | *tos |= kprobe_old_rflags; |
| 503 | break; |
Prasanna S Panchamukhi | 0b9e2ca | 2005-05-05 16:15:40 -0700 | [diff] [blame] | 504 | case 0xc3: /* ret/lret */ |
| 505 | case 0xcb: |
| 506 | case 0xc2: |
| 507 | case 0xca: |
| 508 | regs->eflags &= ~TF_MASK; |
| 509 | /* rip is already adjusted, no more changes required*/ |
| 510 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 511 | case 0xe8: /* call relative - Fix return addr */ |
| 512 | *tos = orig_rip + (*tos - copy_rip); |
| 513 | break; |
| 514 | case 0xff: |
| 515 | if ((*insn & 0x30) == 0x10) { |
| 516 | /* call absolute, indirect */ |
| 517 | /* Fix return addr; rip is correct. */ |
| 518 | next_rip = regs->rip; |
| 519 | *tos = orig_rip + (*tos - copy_rip); |
| 520 | } else if (((*insn & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
| 521 | ((*insn & 0x31) == 0x21)) { /* jmp far, absolute indirect */ |
| 522 | /* rip is correct. */ |
| 523 | next_rip = regs->rip; |
| 524 | } |
| 525 | break; |
| 526 | case 0xea: /* jmp absolute -- rip is correct */ |
| 527 | next_rip = regs->rip; |
| 528 | break; |
| 529 | default: |
| 530 | break; |
| 531 | } |
| 532 | |
| 533 | regs->eflags &= ~TF_MASK; |
| 534 | if (next_rip) { |
| 535 | regs->rip = next_rip; |
| 536 | } else { |
| 537 | regs->rip = orig_rip + (regs->rip - copy_rip); |
| 538 | } |
| 539 | } |
| 540 | |
| 541 | /* |
| 542 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they |
| 543 | * remain disabled thoroughout this function. And we hold kprobe lock. |
| 544 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 545 | int __kprobes post_kprobe_handler(struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 546 | { |
| 547 | if (!kprobe_running()) |
| 548 | return 0; |
| 549 | |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 550 | if ((kprobe_status != KPROBE_REENTER) && current_kprobe->post_handler) { |
| 551 | kprobe_status = KPROBE_HIT_SSDONE; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 552 | current_kprobe->post_handler(current_kprobe, regs, 0); |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 553 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 554 | |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 555 | resume_execution(current_kprobe, regs); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 556 | regs->eflags |= kprobe_saved_rflags; |
| 557 | |
Prasanna S Panchamukhi | aa3d7e3 | 2005-06-23 00:09:37 -0700 | [diff] [blame] | 558 | /* Restore the original saved kprobes variables and continue. */ |
| 559 | if (kprobe_status == KPROBE_REENTER) { |
| 560 | restore_previous_kprobe(); |
| 561 | goto out; |
| 562 | } else { |
| 563 | unlock_kprobes(); |
| 564 | } |
| 565 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 566 | preempt_enable_no_resched(); |
| 567 | |
| 568 | /* |
| 569 | * if somebody else is singlestepping across a probe point, eflags |
| 570 | * will have TF set, in which case, continue the remaining processing |
| 571 | * of do_debug, as if this is not a probe hit. |
| 572 | */ |
| 573 | if (regs->eflags & TF_MASK) |
| 574 | return 0; |
| 575 | |
| 576 | return 1; |
| 577 | } |
| 578 | |
| 579 | /* Interrupts disabled, kprobe_lock held. */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 580 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 581 | { |
| 582 | if (current_kprobe->fault_handler |
| 583 | && current_kprobe->fault_handler(current_kprobe, regs, trapnr)) |
| 584 | return 1; |
| 585 | |
| 586 | if (kprobe_status & KPROBE_HIT_SS) { |
| 587 | resume_execution(current_kprobe, regs); |
| 588 | regs->eflags |= kprobe_old_rflags; |
| 589 | |
| 590 | unlock_kprobes(); |
| 591 | preempt_enable_no_resched(); |
| 592 | } |
| 593 | return 0; |
| 594 | } |
| 595 | |
| 596 | /* |
| 597 | * Wrapper routine for handling exceptions. |
| 598 | */ |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 599 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
| 600 | unsigned long val, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 601 | { |
| 602 | struct die_args *args = (struct die_args *)data; |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 603 | int ret = NOTIFY_DONE; |
| 604 | |
| 605 | preempt_disable(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 606 | switch (val) { |
| 607 | case DIE_INT3: |
| 608 | if (kprobe_handler(args->regs)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 609 | ret = NOTIFY_STOP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 610 | break; |
| 611 | case DIE_DEBUG: |
| 612 | if (post_kprobe_handler(args->regs)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 613 | ret = NOTIFY_STOP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 614 | break; |
| 615 | case DIE_GPF: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 616 | case DIE_PAGE_FAULT: |
| 617 | if (kprobe_running() && |
| 618 | kprobe_fault_handler(args->regs, args->trapnr)) |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 619 | ret = NOTIFY_STOP; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 620 | break; |
| 621 | default: |
| 622 | break; |
| 623 | } |
Ananth N Mavinakayanahalli | 66ff2d0 | 2005-11-07 01:00:07 -0800 | [diff] [blame^] | 624 | preempt_enable(); |
| 625 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 626 | } |
| 627 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 628 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 629 | { |
| 630 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 631 | unsigned long addr; |
| 632 | |
| 633 | jprobe_saved_regs = *regs; |
| 634 | jprobe_saved_rsp = (long *) regs->rsp; |
| 635 | addr = (unsigned long)jprobe_saved_rsp; |
| 636 | /* |
| 637 | * As Linus pointed out, gcc assumes that the callee |
| 638 | * owns the argument space and could overwrite it, e.g. |
| 639 | * tailcall optimization. So, to be absolutely safe |
| 640 | * we also save and restore enough stack bytes to cover |
| 641 | * the argument area. |
| 642 | */ |
| 643 | memcpy(jprobes_stack, (kprobe_opcode_t *) addr, MIN_STACK_SIZE(addr)); |
| 644 | regs->eflags &= ~IF_MASK; |
| 645 | regs->rip = (unsigned long)(jp->entry); |
| 646 | return 1; |
| 647 | } |
| 648 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 649 | void __kprobes jprobe_return(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 650 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 651 | asm volatile (" xchg %%rbx,%%rsp \n" |
| 652 | " int3 \n" |
| 653 | " .globl jprobe_return_end \n" |
| 654 | " jprobe_return_end: \n" |
| 655 | " nop \n"::"b" |
| 656 | (jprobe_saved_rsp):"memory"); |
| 657 | } |
| 658 | |
Prasanna S Panchamukhi | 0f2fbdc | 2005-09-06 15:19:28 -0700 | [diff] [blame] | 659 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 660 | { |
| 661 | u8 *addr = (u8 *) (regs->rip - 1); |
| 662 | unsigned long stack_addr = (unsigned long)jprobe_saved_rsp; |
| 663 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
| 664 | |
| 665 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { |
| 666 | if ((long *)regs->rsp != jprobe_saved_rsp) { |
| 667 | struct pt_regs *saved_regs = |
| 668 | container_of(jprobe_saved_rsp, struct pt_regs, rsp); |
| 669 | printk("current rsp %p does not match saved rsp %p\n", |
| 670 | (long *)regs->rsp, jprobe_saved_rsp); |
| 671 | printk("Saved registers for jprobe %p\n", jp); |
| 672 | show_registers(saved_regs); |
| 673 | printk("Current registers\n"); |
| 674 | show_registers(regs); |
| 675 | BUG(); |
| 676 | } |
| 677 | *regs = jprobe_saved_regs; |
| 678 | memcpy((kprobe_opcode_t *) stack_addr, jprobes_stack, |
| 679 | MIN_STACK_SIZE(stack_addr)); |
| 680 | return 1; |
| 681 | } |
| 682 | return 0; |
| 683 | } |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 684 | |
| 685 | static struct kprobe trampoline_p = { |
| 686 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, |
| 687 | .pre_handler = trampoline_probe_handler |
| 688 | }; |
| 689 | |
Rusty Lynch | 6772926 | 2005-07-05 18:54:50 -0700 | [diff] [blame] | 690 | int __init arch_init_kprobes(void) |
Rusty Lynch | ba8af12 | 2005-06-27 15:17:10 -0700 | [diff] [blame] | 691 | { |
| 692 | return register_kprobe(&trampoline_p); |
| 693 | } |