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