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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
1da177e4 LT |
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-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi | |
26 | * <prasanna@in.ibm.com> adapted for x86_64 | |
27 | * 2005-Mar Roland McGrath <roland@redhat.com> | |
28 | * Fixed to handle %rip-relative addressing mode correctly. | |
73649dab RL |
29 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> |
30 | * Added function return probes functionality | |
1da177e4 LT |
31 | */ |
32 | ||
1da177e4 LT |
33 | #include <linux/kprobes.h> |
34 | #include <linux/ptrace.h> | |
1da177e4 LT |
35 | #include <linux/string.h> |
36 | #include <linux/slab.h> | |
37 | #include <linux/preempt.h> | |
c28f8966 | 38 | #include <linux/module.h> |
1eeb66a1 | 39 | #include <linux/kdebug.h> |
9ec4b1f3 | 40 | |
1da177e4 | 41 | #include <asm/pgtable.h> |
c28f8966 | 42 | #include <asm/uaccess.h> |
19d36ccd | 43 | #include <asm/alternative.h> |
1da177e4 | 44 | |
1da177e4 | 45 | void jprobe_return_end(void); |
f709b122 | 46 | static void __kprobes arch_copy_kprobe(struct kprobe *p); |
1da177e4 | 47 | |
e7a510f9 AM |
48 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
49 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 50 | |
f438d914 MH |
51 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
52 | {"__switch_to", }, /* This function switches only current task, but | |
53 | doesn't switch kernel stack.*/ | |
54 | {NULL, NULL} /* Terminator */ | |
55 | }; | |
56 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
57 | ||
1da177e4 LT |
58 | /* |
59 | * returns non-zero if opcode modifies the interrupt flag. | |
60 | */ | |
8645419c | 61 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
62 | { |
63 | switch (*insn) { | |
64 | case 0xfa: /* cli */ | |
65 | case 0xfb: /* sti */ | |
66 | case 0xcf: /* iret/iretd */ | |
67 | case 0x9d: /* popf/popfd */ | |
68 | return 1; | |
69 | } | |
70 | ||
71 | if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf) | |
72 | return 1; | |
73 | return 0; | |
74 | } | |
75 | ||
0f2fbdcb | 76 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 LT |
77 | { |
78 | /* insn: must be on special executable page on x86_64. */ | |
2dd960d6 | 79 | p->ainsn.insn = get_insn_slot(); |
1da177e4 LT |
80 | if (!p->ainsn.insn) { |
81 | return -ENOMEM; | |
82 | } | |
49a2a1b8 | 83 | arch_copy_kprobe(p); |
1da177e4 LT |
84 | return 0; |
85 | } | |
86 | ||
87 | /* | |
88 | * Determine if the instruction uses the %rip-relative addressing mode. | |
89 | * If it does, return the address of the 32-bit displacement word. | |
90 | * If not, return null. | |
91 | */ | |
3b60211c | 92 | static s32 __kprobes *is_riprel(u8 *insn) |
1da177e4 LT |
93 | { |
94 | #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ | |
95 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
96 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
97 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
98 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
99 | << (row % 64)) | |
100 | static const u64 onebyte_has_modrm[256 / 64] = { | |
101 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
102 | /* ------------------------------- */ | |
103 | W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */ | |
104 | W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */ | |
105 | W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */ | |
106 | W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */ | |
107 | W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */ | |
108 | W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */ | |
109 | W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */ | |
110 | W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */ | |
111 | W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */ | |
112 | W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */ | |
113 | W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */ | |
114 | W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */ | |
115 | W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */ | |
116 | W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */ | |
117 | W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */ | |
118 | W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */ | |
119 | /* ------------------------------- */ | |
120 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
121 | }; | |
122 | static const u64 twobyte_has_modrm[256 / 64] = { | |
123 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
124 | /* ------------------------------- */ | |
125 | W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */ | |
126 | W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */ | |
127 | W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */ | |
128 | W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */ | |
129 | W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */ | |
130 | W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */ | |
131 | W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */ | |
132 | W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */ | |
133 | W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */ | |
134 | W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */ | |
135 | W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */ | |
136 | W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */ | |
137 | W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */ | |
138 | W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */ | |
139 | W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */ | |
140 | W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */ | |
141 | /* ------------------------------- */ | |
142 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
143 | }; | |
144 | #undef W | |
145 | int need_modrm; | |
146 | ||
147 | /* Skip legacy instruction prefixes. */ | |
148 | while (1) { | |
149 | switch (*insn) { | |
150 | case 0x66: | |
151 | case 0x67: | |
152 | case 0x2e: | |
153 | case 0x3e: | |
154 | case 0x26: | |
155 | case 0x64: | |
156 | case 0x65: | |
157 | case 0x36: | |
158 | case 0xf0: | |
159 | case 0xf3: | |
160 | case 0xf2: | |
161 | ++insn; | |
162 | continue; | |
163 | } | |
164 | break; | |
165 | } | |
166 | ||
167 | /* Skip REX instruction prefix. */ | |
168 | if ((*insn & 0xf0) == 0x40) | |
169 | ++insn; | |
170 | ||
171 | if (*insn == 0x0f) { /* Two-byte opcode. */ | |
172 | ++insn; | |
173 | need_modrm = test_bit(*insn, twobyte_has_modrm); | |
174 | } else { /* One-byte opcode. */ | |
175 | need_modrm = test_bit(*insn, onebyte_has_modrm); | |
176 | } | |
177 | ||
178 | if (need_modrm) { | |
179 | u8 modrm = *++insn; | |
180 | if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */ | |
181 | /* Displacement follows ModRM byte. */ | |
182 | return (s32 *) ++insn; | |
183 | } | |
184 | } | |
185 | ||
186 | /* No %rip-relative addressing mode here. */ | |
187 | return NULL; | |
188 | } | |
189 | ||
f709b122 | 190 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 LT |
191 | { |
192 | s32 *ripdisp; | |
193 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); | |
194 | ripdisp = is_riprel(p->ainsn.insn); | |
195 | if (ripdisp) { | |
196 | /* | |
197 | * The copied instruction uses the %rip-relative | |
198 | * addressing mode. Adjust the displacement for the | |
199 | * difference between the original location of this | |
200 | * instruction and the location of the copy that will | |
201 | * actually be run. The tricky bit here is making sure | |
202 | * that the sign extension happens correctly in this | |
203 | * calculation, since we need a signed 32-bit result to | |
204 | * be sign-extended to 64 bits when it's added to the | |
205 | * %rip value and yield the same 64-bit result that the | |
206 | * sign-extension of the original signed 32-bit | |
207 | * displacement would have given. | |
208 | */ | |
209 | s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn; | |
210 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ | |
211 | *ripdisp = disp; | |
212 | } | |
7e1048b1 | 213 | p->opcode = *p->addr; |
1da177e4 LT |
214 | } |
215 | ||
0f2fbdcb | 216 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 217 | { |
19d36ccd | 218 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
219 | } |
220 | ||
0f2fbdcb | 221 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 222 | { |
19d36ccd | 223 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
224 | } |
225 | ||
0498b635 | 226 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 227 | { |
7a7d1cf9 | 228 | mutex_lock(&kprobe_mutex); |
b4c6c34a | 229 | free_insn_slot(p->ainsn.insn, 0); |
7a7d1cf9 | 230 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
231 | } |
232 | ||
3b60211c | 233 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 234 | { |
e7a510f9 AM |
235 | kcb->prev_kprobe.kp = kprobe_running(); |
236 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
237 | kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags; | |
238 | kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags; | |
aa3d7e3d PP |
239 | } |
240 | ||
3b60211c | 241 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 242 | { |
e7a510f9 AM |
243 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
244 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
245 | kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags; | |
246 | kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags; | |
aa3d7e3d PP |
247 | } |
248 | ||
3b60211c | 249 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 250 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 251 | { |
e7a510f9 AM |
252 | __get_cpu_var(current_kprobe) = p; |
253 | kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags | |
aa3d7e3d PP |
254 | = (regs->eflags & (TF_MASK | IF_MASK)); |
255 | if (is_IF_modifier(p->ainsn.insn)) | |
e7a510f9 | 256 | kcb->kprobe_saved_rflags &= ~IF_MASK; |
aa3d7e3d PP |
257 | } |
258 | ||
0f2fbdcb | 259 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
260 | { |
261 | regs->eflags |= TF_MASK; | |
262 | regs->eflags &= ~IF_MASK; | |
263 | /*single step inline if the instruction is an int3*/ | |
264 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
265 | regs->rip = (unsigned long)p->addr; | |
266 | else | |
267 | regs->rip = (unsigned long)p->ainsn.insn; | |
268 | } | |
269 | ||
991a51d8 | 270 | /* Called with kretprobe_lock held */ |
4c4308cb | 271 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 272 | struct pt_regs *regs) |
73649dab RL |
273 | { |
274 | unsigned long *sara = (unsigned long *)regs->rsp; | |
ba8af12f | 275 | |
4c4308cb CH |
276 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
277 | /* Replace the return addr with trampoline addr */ | |
278 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab RL |
279 | } |
280 | ||
0f2fbdcb | 281 | int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
282 | { |
283 | struct kprobe *p; | |
284 | int ret = 0; | |
285 | kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t)); | |
d217d545 AM |
286 | struct kprobe_ctlblk *kcb; |
287 | ||
288 | /* | |
289 | * We don't want to be preempted for the entire | |
290 | * duration of kprobe processing | |
291 | */ | |
292 | preempt_disable(); | |
293 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 294 | |
1da177e4 LT |
295 | /* Check we're not actually recursing */ |
296 | if (kprobe_running()) { | |
1da177e4 LT |
297 | p = get_kprobe(addr); |
298 | if (p) { | |
e7a510f9 | 299 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 300 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
1da177e4 | 301 | regs->eflags &= ~TF_MASK; |
e7a510f9 | 302 | regs->eflags |= kcb->kprobe_saved_rflags; |
1da177e4 | 303 | goto no_kprobe; |
e7a510f9 | 304 | } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
aa3d7e3d PP |
305 | /* TODO: Provide re-entrancy from |
306 | * post_kprobes_handler() and avoid exception | |
307 | * stack corruption while single-stepping on | |
308 | * the instruction of the new probe. | |
309 | */ | |
310 | arch_disarm_kprobe(p); | |
311 | regs->rip = (unsigned long)p->addr; | |
e7a510f9 | 312 | reset_current_kprobe(); |
aa3d7e3d PP |
313 | ret = 1; |
314 | } else { | |
315 | /* We have reentered the kprobe_handler(), since | |
316 | * another probe was hit while within the | |
317 | * handler. We here save the original kprobe | |
318 | * variables and just single step on instruction | |
319 | * of the new probe without calling any user | |
320 | * handlers. | |
321 | */ | |
e7a510f9 AM |
322 | save_previous_kprobe(kcb); |
323 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 324 | kprobes_inc_nmissed_count(p); |
aa3d7e3d | 325 | prepare_singlestep(p, regs); |
e7a510f9 | 326 | kcb->kprobe_status = KPROBE_REENTER; |
aa3d7e3d | 327 | return 1; |
1da177e4 | 328 | } |
1da177e4 | 329 | } else { |
eb3a7292 KA |
330 | if (*addr != BREAKPOINT_INSTRUCTION) { |
331 | /* The breakpoint instruction was removed by | |
332 | * another cpu right after we hit, no further | |
333 | * handling of this interrupt is appropriate | |
334 | */ | |
335 | regs->rip = (unsigned long)addr; | |
336 | ret = 1; | |
337 | goto no_kprobe; | |
338 | } | |
e7a510f9 | 339 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
340 | if (p->break_handler && p->break_handler(p, regs)) { |
341 | goto ss_probe; | |
342 | } | |
343 | } | |
1da177e4 LT |
344 | goto no_kprobe; |
345 | } | |
346 | ||
1da177e4 LT |
347 | p = get_kprobe(addr); |
348 | if (!p) { | |
1da177e4 LT |
349 | if (*addr != BREAKPOINT_INSTRUCTION) { |
350 | /* | |
351 | * The breakpoint instruction was removed right | |
352 | * after we hit it. Another cpu has removed | |
353 | * either a probepoint or a debugger breakpoint | |
354 | * at this address. In either case, no further | |
355 | * handling of this interrupt is appropriate. | |
bce06494 JK |
356 | * Back up over the (now missing) int3 and run |
357 | * the original instruction. | |
1da177e4 | 358 | */ |
bce06494 | 359 | regs->rip = (unsigned long)addr; |
1da177e4 LT |
360 | ret = 1; |
361 | } | |
362 | /* Not one of ours: let kernel handle it */ | |
363 | goto no_kprobe; | |
364 | } | |
365 | ||
e7a510f9 AM |
366 | set_current_kprobe(p, regs, kcb); |
367 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
368 | |
369 | if (p->pre_handler && p->pre_handler(p, regs)) | |
370 | /* handler has already set things up, so skip ss setup */ | |
371 | return 1; | |
372 | ||
373 | ss_probe: | |
374 | prepare_singlestep(p, regs); | |
e7a510f9 | 375 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
376 | return 1; |
377 | ||
378 | no_kprobe: | |
d217d545 | 379 | preempt_enable_no_resched(); |
1da177e4 LT |
380 | return ret; |
381 | } | |
382 | ||
73649dab RL |
383 | /* |
384 | * For function-return probes, init_kprobes() establishes a probepoint | |
385 | * here. When a retprobed function returns, this probe is hit and | |
386 | * trampoline_probe_handler() runs, calling the kretprobe's handler. | |
387 | */ | |
388 | void kretprobe_trampoline_holder(void) | |
389 | { | |
390 | asm volatile ( ".global kretprobe_trampoline\n" | |
391 | "kretprobe_trampoline: \n" | |
392 | "nop\n"); | |
393 | } | |
394 | ||
395 | /* | |
396 | * Called when we hit the probe point at kretprobe_trampoline | |
397 | */ | |
0f2fbdcb | 398 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
73649dab | 399 | { |
62c27be0 | 400 | struct kretprobe_instance *ri = NULL; |
99219a3f | 401 | struct hlist_head *head, empty_rp; |
62c27be0 | 402 | struct hlist_node *node, *tmp; |
991a51d8 | 403 | unsigned long flags, orig_ret_address = 0; |
ba8af12f | 404 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
73649dab | 405 | |
99219a3f | 406 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 407 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 408 | head = kretprobe_inst_table_head(current); |
73649dab | 409 | |
ba8af12f RL |
410 | /* |
411 | * It is possible to have multiple instances associated with a given | |
412 | * task either because an multiple functions in the call path | |
413 | * have a return probe installed on them, and/or more then one return | |
414 | * return probe was registered for a target function. | |
415 | * | |
416 | * We can handle this because: | |
417 | * - instances are always inserted at the head of the list | |
418 | * - when multiple return probes are registered for the same | |
62c27be0 | 419 | * function, the first instance's ret_addr will point to the |
ba8af12f RL |
420 | * real return address, and all the rest will point to |
421 | * kretprobe_trampoline | |
422 | */ | |
423 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 424 | if (ri->task != current) |
ba8af12f | 425 | /* another task is sharing our hash bucket */ |
62c27be0 | 426 | continue; |
ba8af12f RL |
427 | |
428 | if (ri->rp && ri->rp->handler) | |
429 | ri->rp->handler(ri, regs); | |
430 | ||
431 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 432 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
433 | |
434 | if (orig_ret_address != trampoline_address) | |
435 | /* | |
436 | * This is the real return address. Any other | |
437 | * instances associated with this task are for | |
438 | * other calls deeper on the call stack | |
439 | */ | |
440 | break; | |
73649dab | 441 | } |
ba8af12f | 442 | |
0f95b7fc | 443 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f RL |
444 | regs->rip = orig_ret_address; |
445 | ||
e7a510f9 | 446 | reset_current_kprobe(); |
991a51d8 | 447 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
ba8af12f RL |
448 | preempt_enable_no_resched(); |
449 | ||
99219a3f | 450 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
451 | hlist_del(&ri->hlist); | |
452 | kfree(ri); | |
453 | } | |
62c27be0 | 454 | /* |
455 | * By returning a non-zero value, we are telling | |
456 | * kprobe_handler() that we don't want the post_handler | |
d217d545 | 457 | * to run (and have re-enabled preemption) |
62c27be0 | 458 | */ |
459 | return 1; | |
73649dab RL |
460 | } |
461 | ||
1da177e4 LT |
462 | /* |
463 | * Called after single-stepping. p->addr is the address of the | |
464 | * instruction whose first byte has been replaced by the "int 3" | |
465 | * instruction. To avoid the SMP problems that can occur when we | |
466 | * temporarily put back the original opcode to single-step, we | |
467 | * single-stepped a copy of the instruction. The address of this | |
468 | * copy is p->ainsn.insn. | |
469 | * | |
470 | * This function prepares to return from the post-single-step | |
471 | * interrupt. We have to fix up the stack as follows: | |
472 | * | |
473 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
474 | * the new rip is relative to the copied instruction. We need to make | |
475 | * it relative to the original instruction. | |
476 | * | |
477 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
478 | * flags are set in the just-pushed eflags, and may need to be cleared. | |
479 | * | |
480 | * 2) If the single-stepped instruction was a call, the return address | |
481 | * that is atop the stack is the address following the copied instruction. | |
482 | * We need to make it the address following the original instruction. | |
483 | */ | |
e7a510f9 AM |
484 | static void __kprobes resume_execution(struct kprobe *p, |
485 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 LT |
486 | { |
487 | unsigned long *tos = (unsigned long *)regs->rsp; | |
488 | unsigned long next_rip = 0; | |
489 | unsigned long copy_rip = (unsigned long)p->ainsn.insn; | |
490 | unsigned long orig_rip = (unsigned long)p->addr; | |
491 | kprobe_opcode_t *insn = p->ainsn.insn; | |
492 | ||
493 | /*skip the REX prefix*/ | |
494 | if (*insn >= 0x40 && *insn <= 0x4f) | |
495 | insn++; | |
496 | ||
497 | switch (*insn) { | |
498 | case 0x9c: /* pushfl */ | |
499 | *tos &= ~(TF_MASK | IF_MASK); | |
e7a510f9 | 500 | *tos |= kcb->kprobe_old_rflags; |
1da177e4 | 501 | break; |
0b9e2cac PP |
502 | case 0xc3: /* ret/lret */ |
503 | case 0xcb: | |
504 | case 0xc2: | |
505 | case 0xca: | |
506 | regs->eflags &= ~TF_MASK; | |
507 | /* rip is already adjusted, no more changes required*/ | |
508 | return; | |
1da177e4 LT |
509 | case 0xe8: /* call relative - Fix return addr */ |
510 | *tos = orig_rip + (*tos - copy_rip); | |
511 | break; | |
512 | case 0xff: | |
dc49e344 | 513 | if ((insn[1] & 0x30) == 0x10) { |
1da177e4 LT |
514 | /* call absolute, indirect */ |
515 | /* Fix return addr; rip is correct. */ | |
516 | next_rip = regs->rip; | |
517 | *tos = orig_rip + (*tos - copy_rip); | |
dc49e344 SO |
518 | } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
519 | ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ | |
1da177e4 LT |
520 | /* rip is correct. */ |
521 | next_rip = regs->rip; | |
522 | } | |
523 | break; | |
524 | case 0xea: /* jmp absolute -- rip is correct */ | |
525 | next_rip = regs->rip; | |
526 | break; | |
527 | default: | |
528 | break; | |
529 | } | |
530 | ||
531 | regs->eflags &= ~TF_MASK; | |
532 | if (next_rip) { | |
533 | regs->rip = next_rip; | |
534 | } else { | |
535 | regs->rip = orig_rip + (regs->rip - copy_rip); | |
536 | } | |
537 | } | |
538 | ||
0f2fbdcb | 539 | int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 540 | { |
e7a510f9 AM |
541 | struct kprobe *cur = kprobe_running(); |
542 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
543 | ||
544 | if (!cur) | |
1da177e4 LT |
545 | return 0; |
546 | ||
e7a510f9 AM |
547 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
548 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
549 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 550 | } |
1da177e4 | 551 | |
e7a510f9 AM |
552 | resume_execution(cur, regs, kcb); |
553 | regs->eflags |= kcb->kprobe_saved_rflags; | |
143a5d32 | 554 | trace_hardirqs_fixup_flags(regs->eflags); |
1da177e4 | 555 | |
aa3d7e3d | 556 | /* Restore the original saved kprobes variables and continue. */ |
e7a510f9 AM |
557 | if (kcb->kprobe_status == KPROBE_REENTER) { |
558 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 559 | goto out; |
aa3d7e3d | 560 | } |
e7a510f9 | 561 | reset_current_kprobe(); |
aa3d7e3d | 562 | out: |
1da177e4 LT |
563 | preempt_enable_no_resched(); |
564 | ||
565 | /* | |
566 | * if somebody else is singlestepping across a probe point, eflags | |
567 | * will have TF set, in which case, continue the remaining processing | |
568 | * of do_debug, as if this is not a probe hit. | |
569 | */ | |
570 | if (regs->eflags & TF_MASK) | |
571 | return 0; | |
572 | ||
573 | return 1; | |
574 | } | |
575 | ||
0f2fbdcb | 576 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 577 | { |
e7a510f9 AM |
578 | struct kprobe *cur = kprobe_running(); |
579 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
c28f8966 | 580 | const struct exception_table_entry *fixup; |
e7a510f9 | 581 | |
c28f8966 PP |
582 | switch(kcb->kprobe_status) { |
583 | case KPROBE_HIT_SS: | |
584 | case KPROBE_REENTER: | |
585 | /* | |
586 | * We are here because the instruction being single | |
587 | * stepped caused a page fault. We reset the current | |
588 | * kprobe and the rip points back to the probe address | |
589 | * and allow the page fault handler to continue as a | |
590 | * normal page fault. | |
591 | */ | |
592 | regs->rip = (unsigned long)cur->addr; | |
e7a510f9 | 593 | regs->eflags |= kcb->kprobe_old_rflags; |
c28f8966 PP |
594 | if (kcb->kprobe_status == KPROBE_REENTER) |
595 | restore_previous_kprobe(kcb); | |
596 | else | |
597 | reset_current_kprobe(); | |
1da177e4 | 598 | preempt_enable_no_resched(); |
c28f8966 PP |
599 | break; |
600 | case KPROBE_HIT_ACTIVE: | |
601 | case KPROBE_HIT_SSDONE: | |
602 | /* | |
603 | * We increment the nmissed count for accounting, | |
604 | * we can also use npre/npostfault count for accouting | |
605 | * these specific fault cases. | |
606 | */ | |
607 | kprobes_inc_nmissed_count(cur); | |
608 | ||
609 | /* | |
610 | * We come here because instructions in the pre/post | |
611 | * handler caused the page_fault, this could happen | |
612 | * if handler tries to access user space by | |
613 | * copy_from_user(), get_user() etc. Let the | |
614 | * user-specified handler try to fix it first. | |
615 | */ | |
616 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
617 | return 1; | |
618 | ||
619 | /* | |
620 | * In case the user-specified fault handler returned | |
621 | * zero, try to fix up. | |
622 | */ | |
623 | fixup = search_exception_tables(regs->rip); | |
624 | if (fixup) { | |
625 | regs->rip = fixup->fixup; | |
626 | return 1; | |
627 | } | |
628 | ||
629 | /* | |
630 | * fixup() could not handle it, | |
631 | * Let do_page_fault() fix it. | |
632 | */ | |
633 | break; | |
634 | default: | |
635 | break; | |
1da177e4 LT |
636 | } |
637 | return 0; | |
638 | } | |
639 | ||
640 | /* | |
641 | * Wrapper routine for handling exceptions. | |
642 | */ | |
0f2fbdcb PP |
643 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
644 | unsigned long val, void *data) | |
1da177e4 LT |
645 | { |
646 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
647 | int ret = NOTIFY_DONE; |
648 | ||
2326c770 | 649 | if (args->regs && user_mode(args->regs)) |
650 | return ret; | |
651 | ||
1da177e4 LT |
652 | switch (val) { |
653 | case DIE_INT3: | |
654 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 655 | ret = NOTIFY_STOP; |
1da177e4 LT |
656 | break; |
657 | case DIE_DEBUG: | |
658 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 659 | ret = NOTIFY_STOP; |
1da177e4 LT |
660 | break; |
661 | case DIE_GPF: | |
d217d545 AM |
662 | /* kprobe_running() needs smp_processor_id() */ |
663 | preempt_disable(); | |
1da177e4 LT |
664 | if (kprobe_running() && |
665 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 666 | ret = NOTIFY_STOP; |
d217d545 | 667 | preempt_enable(); |
1da177e4 LT |
668 | break; |
669 | default: | |
670 | break; | |
671 | } | |
66ff2d06 | 672 | return ret; |
1da177e4 LT |
673 | } |
674 | ||
0f2fbdcb | 675 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
676 | { |
677 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
678 | unsigned long addr; | |
e7a510f9 | 679 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 680 | |
e7a510f9 AM |
681 | kcb->jprobe_saved_regs = *regs; |
682 | kcb->jprobe_saved_rsp = (long *) regs->rsp; | |
683 | addr = (unsigned long)(kcb->jprobe_saved_rsp); | |
1da177e4 LT |
684 | /* |
685 | * As Linus pointed out, gcc assumes that the callee | |
686 | * owns the argument space and could overwrite it, e.g. | |
687 | * tailcall optimization. So, to be absolutely safe | |
688 | * we also save and restore enough stack bytes to cover | |
689 | * the argument area. | |
690 | */ | |
e7a510f9 AM |
691 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
692 | MIN_STACK_SIZE(addr)); | |
1da177e4 | 693 | regs->eflags &= ~IF_MASK; |
58dfe883 | 694 | trace_hardirqs_off(); |
1da177e4 LT |
695 | regs->rip = (unsigned long)(jp->entry); |
696 | return 1; | |
697 | } | |
698 | ||
0f2fbdcb | 699 | void __kprobes jprobe_return(void) |
1da177e4 | 700 | { |
e7a510f9 AM |
701 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
702 | ||
1da177e4 LT |
703 | asm volatile (" xchg %%rbx,%%rsp \n" |
704 | " int3 \n" | |
705 | " .globl jprobe_return_end \n" | |
706 | " jprobe_return_end: \n" | |
707 | " nop \n"::"b" | |
e7a510f9 | 708 | (kcb->jprobe_saved_rsp):"memory"); |
1da177e4 LT |
709 | } |
710 | ||
0f2fbdcb | 711 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 712 | { |
e7a510f9 | 713 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 714 | u8 *addr = (u8 *) (regs->rip - 1); |
e7a510f9 | 715 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp); |
1da177e4 LT |
716 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
717 | ||
718 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { | |
29b6cd79 MH |
719 | if ((unsigned long *)regs->rsp != kcb->jprobe_saved_rsp) { |
720 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; | |
1da177e4 | 721 | printk("current rsp %p does not match saved rsp %p\n", |
e7a510f9 | 722 | (long *)regs->rsp, kcb->jprobe_saved_rsp); |
1da177e4 LT |
723 | printk("Saved registers for jprobe %p\n", jp); |
724 | show_registers(saved_regs); | |
725 | printk("Current registers\n"); | |
726 | show_registers(regs); | |
727 | BUG(); | |
728 | } | |
e7a510f9 AM |
729 | *regs = kcb->jprobe_saved_regs; |
730 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, | |
1da177e4 | 731 | MIN_STACK_SIZE(stack_addr)); |
d217d545 | 732 | preempt_enable_no_resched(); |
1da177e4 LT |
733 | return 1; |
734 | } | |
735 | return 0; | |
736 | } | |
ba8af12f RL |
737 | |
738 | static struct kprobe trampoline_p = { | |
739 | .addr = (kprobe_opcode_t *) &kretprobe_trampoline, | |
740 | .pre_handler = trampoline_probe_handler | |
741 | }; | |
742 | ||
6772926b | 743 | int __init arch_init_kprobes(void) |
ba8af12f RL |
744 | { |
745 | return register_kprobe(&trampoline_p); | |
746 | } | |
bf8f6e5b AM |
747 | |
748 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
749 | { | |
750 | if (p->addr == (kprobe_opcode_t *)&kretprobe_trampoline) | |
751 | return 1; | |
752 | ||
753 | return 0; | |
754 | } |