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