]>
Commit | Line | Data |
---|---|---|
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 LT |
50 | |
51 | /* | |
52 | * returns non-zero if opcode modifies the interrupt flag. | |
53 | */ | |
3b60211c | 54 | static __always_inline int is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
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 | */ | |
3b60211c | 85 | static s32 __kprobes *is_riprel(u8 *insn) |
1da177e4 LT |
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 | { |
19d36ccd | 211 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
212 | } |
213 | ||
0f2fbdcb | 214 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 215 | { |
19d36ccd | 216 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
217 | } |
218 | ||
0498b635 | 219 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 220 | { |
7a7d1cf9 | 221 | mutex_lock(&kprobe_mutex); |
b4c6c34a | 222 | free_insn_slot(p->ainsn.insn, 0); |
7a7d1cf9 | 223 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
224 | } |
225 | ||
3b60211c | 226 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 227 | { |
e7a510f9 AM |
228 | kcb->prev_kprobe.kp = kprobe_running(); |
229 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
230 | kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags; | |
231 | kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags; | |
aa3d7e3d PP |
232 | } |
233 | ||
3b60211c | 234 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 235 | { |
e7a510f9 AM |
236 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
237 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
238 | kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags; | |
239 | kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags; | |
aa3d7e3d PP |
240 | } |
241 | ||
3b60211c | 242 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 243 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 244 | { |
e7a510f9 AM |
245 | __get_cpu_var(current_kprobe) = p; |
246 | kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags | |
aa3d7e3d PP |
247 | = (regs->eflags & (TF_MASK | IF_MASK)); |
248 | if (is_IF_modifier(p->ainsn.insn)) | |
e7a510f9 | 249 | kcb->kprobe_saved_rflags &= ~IF_MASK; |
aa3d7e3d PP |
250 | } |
251 | ||
0f2fbdcb | 252 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
253 | { |
254 | regs->eflags |= TF_MASK; | |
255 | regs->eflags &= ~IF_MASK; | |
256 | /*single step inline if the instruction is an int3*/ | |
257 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
258 | regs->rip = (unsigned long)p->addr; | |
259 | else | |
260 | regs->rip = (unsigned long)p->ainsn.insn; | |
261 | } | |
262 | ||
991a51d8 | 263 | /* Called with kretprobe_lock held */ |
4c4308cb | 264 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 265 | struct pt_regs *regs) |
73649dab RL |
266 | { |
267 | unsigned long *sara = (unsigned long *)regs->rsp; | |
ba8af12f | 268 | |
4c4308cb CH |
269 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
270 | /* Replace the return addr with trampoline addr */ | |
271 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab RL |
272 | } |
273 | ||
0f2fbdcb | 274 | int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
275 | { |
276 | struct kprobe *p; | |
277 | int ret = 0; | |
278 | kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->rip - sizeof(kprobe_opcode_t)); | |
d217d545 AM |
279 | struct kprobe_ctlblk *kcb; |
280 | ||
281 | /* | |
282 | * We don't want to be preempted for the entire | |
283 | * duration of kprobe processing | |
284 | */ | |
285 | preempt_disable(); | |
286 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 287 | |
1da177e4 LT |
288 | /* Check we're not actually recursing */ |
289 | if (kprobe_running()) { | |
1da177e4 LT |
290 | p = get_kprobe(addr); |
291 | if (p) { | |
e7a510f9 | 292 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 293 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
1da177e4 | 294 | regs->eflags &= ~TF_MASK; |
e7a510f9 | 295 | regs->eflags |= kcb->kprobe_saved_rflags; |
1da177e4 | 296 | goto no_kprobe; |
e7a510f9 | 297 | } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
aa3d7e3d PP |
298 | /* TODO: Provide re-entrancy from |
299 | * post_kprobes_handler() and avoid exception | |
300 | * stack corruption while single-stepping on | |
301 | * the instruction of the new probe. | |
302 | */ | |
303 | arch_disarm_kprobe(p); | |
304 | regs->rip = (unsigned long)p->addr; | |
e7a510f9 | 305 | reset_current_kprobe(); |
aa3d7e3d PP |
306 | ret = 1; |
307 | } else { | |
308 | /* We have reentered the kprobe_handler(), since | |
309 | * another probe was hit while within the | |
310 | * handler. We here save the original kprobe | |
311 | * variables and just single step on instruction | |
312 | * of the new probe without calling any user | |
313 | * handlers. | |
314 | */ | |
e7a510f9 AM |
315 | save_previous_kprobe(kcb); |
316 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 317 | kprobes_inc_nmissed_count(p); |
aa3d7e3d | 318 | prepare_singlestep(p, regs); |
e7a510f9 | 319 | kcb->kprobe_status = KPROBE_REENTER; |
aa3d7e3d | 320 | return 1; |
1da177e4 | 321 | } |
1da177e4 | 322 | } else { |
eb3a7292 KA |
323 | if (*addr != BREAKPOINT_INSTRUCTION) { |
324 | /* The breakpoint instruction was removed by | |
325 | * another cpu right after we hit, no further | |
326 | * handling of this interrupt is appropriate | |
327 | */ | |
328 | regs->rip = (unsigned long)addr; | |
329 | ret = 1; | |
330 | goto no_kprobe; | |
331 | } | |
e7a510f9 | 332 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
333 | if (p->break_handler && p->break_handler(p, regs)) { |
334 | goto ss_probe; | |
335 | } | |
336 | } | |
1da177e4 LT |
337 | goto no_kprobe; |
338 | } | |
339 | ||
1da177e4 LT |
340 | p = get_kprobe(addr); |
341 | if (!p) { | |
1da177e4 LT |
342 | if (*addr != BREAKPOINT_INSTRUCTION) { |
343 | /* | |
344 | * The breakpoint instruction was removed right | |
345 | * after we hit it. Another cpu has removed | |
346 | * either a probepoint or a debugger breakpoint | |
347 | * at this address. In either case, no further | |
348 | * handling of this interrupt is appropriate. | |
bce06494 JK |
349 | * Back up over the (now missing) int3 and run |
350 | * the original instruction. | |
1da177e4 | 351 | */ |
bce06494 | 352 | regs->rip = (unsigned long)addr; |
1da177e4 LT |
353 | ret = 1; |
354 | } | |
355 | /* Not one of ours: let kernel handle it */ | |
356 | goto no_kprobe; | |
357 | } | |
358 | ||
e7a510f9 AM |
359 | set_current_kprobe(p, regs, kcb); |
360 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
361 | |
362 | if (p->pre_handler && p->pre_handler(p, regs)) | |
363 | /* handler has already set things up, so skip ss setup */ | |
364 | return 1; | |
365 | ||
366 | ss_probe: | |
367 | prepare_singlestep(p, regs); | |
e7a510f9 | 368 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
369 | return 1; |
370 | ||
371 | no_kprobe: | |
d217d545 | 372 | preempt_enable_no_resched(); |
1da177e4 LT |
373 | return ret; |
374 | } | |
375 | ||
73649dab RL |
376 | /* |
377 | * For function-return probes, init_kprobes() establishes a probepoint | |
378 | * here. When a retprobed function returns, this probe is hit and | |
379 | * trampoline_probe_handler() runs, calling the kretprobe's handler. | |
380 | */ | |
381 | void kretprobe_trampoline_holder(void) | |
382 | { | |
383 | asm volatile ( ".global kretprobe_trampoline\n" | |
384 | "kretprobe_trampoline: \n" | |
385 | "nop\n"); | |
386 | } | |
387 | ||
388 | /* | |
389 | * Called when we hit the probe point at kretprobe_trampoline | |
390 | */ | |
0f2fbdcb | 391 | int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs) |
73649dab | 392 | { |
62c27be0 | 393 | struct kretprobe_instance *ri = NULL; |
99219a3f | 394 | struct hlist_head *head, empty_rp; |
62c27be0 | 395 | struct hlist_node *node, *tmp; |
991a51d8 | 396 | unsigned long flags, orig_ret_address = 0; |
ba8af12f | 397 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
73649dab | 398 | |
99219a3f | 399 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 400 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 401 | head = kretprobe_inst_table_head(current); |
73649dab | 402 | |
ba8af12f RL |
403 | /* |
404 | * It is possible to have multiple instances associated with a given | |
405 | * task either because an multiple functions in the call path | |
406 | * have a return probe installed on them, and/or more then one return | |
407 | * return probe was registered for a target function. | |
408 | * | |
409 | * We can handle this because: | |
410 | * - instances are always inserted at the head of the list | |
411 | * - when multiple return probes are registered for the same | |
62c27be0 | 412 | * function, the first instance's ret_addr will point to the |
ba8af12f RL |
413 | * real return address, and all the rest will point to |
414 | * kretprobe_trampoline | |
415 | */ | |
416 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 417 | if (ri->task != current) |
ba8af12f | 418 | /* another task is sharing our hash bucket */ |
62c27be0 | 419 | continue; |
ba8af12f RL |
420 | |
421 | if (ri->rp && ri->rp->handler) | |
422 | ri->rp->handler(ri, regs); | |
423 | ||
424 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 425 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
426 | |
427 | if (orig_ret_address != trampoline_address) | |
428 | /* | |
429 | * This is the real return address. Any other | |
430 | * instances associated with this task are for | |
431 | * other calls deeper on the call stack | |
432 | */ | |
433 | break; | |
73649dab | 434 | } |
ba8af12f | 435 | |
0f95b7fc | 436 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f RL |
437 | regs->rip = orig_ret_address; |
438 | ||
e7a510f9 | 439 | reset_current_kprobe(); |
991a51d8 | 440 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
ba8af12f RL |
441 | preempt_enable_no_resched(); |
442 | ||
99219a3f | 443 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
444 | hlist_del(&ri->hlist); | |
445 | kfree(ri); | |
446 | } | |
62c27be0 | 447 | /* |
448 | * By returning a non-zero value, we are telling | |
449 | * kprobe_handler() that we don't want the post_handler | |
d217d545 | 450 | * to run (and have re-enabled preemption) |
62c27be0 | 451 | */ |
452 | return 1; | |
73649dab RL |
453 | } |
454 | ||
1da177e4 LT |
455 | /* |
456 | * Called after single-stepping. p->addr is the address of the | |
457 | * instruction whose first byte has been replaced by the "int 3" | |
458 | * instruction. To avoid the SMP problems that can occur when we | |
459 | * temporarily put back the original opcode to single-step, we | |
460 | * single-stepped a copy of the instruction. The address of this | |
461 | * copy is p->ainsn.insn. | |
462 | * | |
463 | * This function prepares to return from the post-single-step | |
464 | * interrupt. We have to fix up the stack as follows: | |
465 | * | |
466 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
467 | * the new rip is relative to the copied instruction. We need to make | |
468 | * it relative to the original instruction. | |
469 | * | |
470 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
471 | * flags are set in the just-pushed eflags, and may need to be cleared. | |
472 | * | |
473 | * 2) If the single-stepped instruction was a call, the return address | |
474 | * that is atop the stack is the address following the copied instruction. | |
475 | * We need to make it the address following the original instruction. | |
476 | */ | |
e7a510f9 AM |
477 | static void __kprobes resume_execution(struct kprobe *p, |
478 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 LT |
479 | { |
480 | unsigned long *tos = (unsigned long *)regs->rsp; | |
481 | unsigned long next_rip = 0; | |
482 | unsigned long copy_rip = (unsigned long)p->ainsn.insn; | |
483 | unsigned long orig_rip = (unsigned long)p->addr; | |
484 | kprobe_opcode_t *insn = p->ainsn.insn; | |
485 | ||
486 | /*skip the REX prefix*/ | |
487 | if (*insn >= 0x40 && *insn <= 0x4f) | |
488 | insn++; | |
489 | ||
490 | switch (*insn) { | |
491 | case 0x9c: /* pushfl */ | |
492 | *tos &= ~(TF_MASK | IF_MASK); | |
e7a510f9 | 493 | *tos |= kcb->kprobe_old_rflags; |
1da177e4 | 494 | break; |
0b9e2cac PP |
495 | case 0xc3: /* ret/lret */ |
496 | case 0xcb: | |
497 | case 0xc2: | |
498 | case 0xca: | |
499 | regs->eflags &= ~TF_MASK; | |
500 | /* rip is already adjusted, no more changes required*/ | |
501 | return; | |
1da177e4 LT |
502 | case 0xe8: /* call relative - Fix return addr */ |
503 | *tos = orig_rip + (*tos - copy_rip); | |
504 | break; | |
505 | case 0xff: | |
dc49e344 | 506 | if ((insn[1] & 0x30) == 0x10) { |
1da177e4 LT |
507 | /* call absolute, indirect */ |
508 | /* Fix return addr; rip is correct. */ | |
509 | next_rip = regs->rip; | |
510 | *tos = orig_rip + (*tos - copy_rip); | |
dc49e344 SO |
511 | } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
512 | ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ | |
1da177e4 LT |
513 | /* rip is correct. */ |
514 | next_rip = regs->rip; | |
515 | } | |
516 | break; | |
517 | case 0xea: /* jmp absolute -- rip is correct */ | |
518 | next_rip = regs->rip; | |
519 | break; | |
520 | default: | |
521 | break; | |
522 | } | |
523 | ||
524 | regs->eflags &= ~TF_MASK; | |
525 | if (next_rip) { | |
526 | regs->rip = next_rip; | |
527 | } else { | |
528 | regs->rip = orig_rip + (regs->rip - copy_rip); | |
529 | } | |
530 | } | |
531 | ||
0f2fbdcb | 532 | int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 533 | { |
e7a510f9 AM |
534 | struct kprobe *cur = kprobe_running(); |
535 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
536 | ||
537 | if (!cur) | |
1da177e4 LT |
538 | return 0; |
539 | ||
e7a510f9 AM |
540 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
541 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
542 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 543 | } |
1da177e4 | 544 | |
e7a510f9 AM |
545 | resume_execution(cur, regs, kcb); |
546 | regs->eflags |= kcb->kprobe_saved_rflags; | |
58dfe883 PZ |
547 | #ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT |
548 | if (raw_irqs_disabled_flags(regs->eflags)) | |
549 | trace_hardirqs_off(); | |
550 | else | |
551 | trace_hardirqs_on(); | |
552 | #endif | |
1da177e4 | 553 | |
aa3d7e3d | 554 | /* Restore the original saved kprobes variables and continue. */ |
e7a510f9 AM |
555 | if (kcb->kprobe_status == KPROBE_REENTER) { |
556 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 557 | goto out; |
aa3d7e3d | 558 | } |
e7a510f9 | 559 | reset_current_kprobe(); |
aa3d7e3d | 560 | out: |
1da177e4 LT |
561 | preempt_enable_no_resched(); |
562 | ||
563 | /* | |
564 | * if somebody else is singlestepping across a probe point, eflags | |
565 | * will have TF set, in which case, continue the remaining processing | |
566 | * of do_debug, as if this is not a probe hit. | |
567 | */ | |
568 | if (regs->eflags & TF_MASK) | |
569 | return 0; | |
570 | ||
571 | return 1; | |
572 | } | |
573 | ||
0f2fbdcb | 574 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 575 | { |
e7a510f9 AM |
576 | struct kprobe *cur = kprobe_running(); |
577 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
c28f8966 | 578 | const struct exception_table_entry *fixup; |
e7a510f9 | 579 | |
c28f8966 PP |
580 | switch(kcb->kprobe_status) { |
581 | case KPROBE_HIT_SS: | |
582 | case KPROBE_REENTER: | |
583 | /* | |
584 | * We are here because the instruction being single | |
585 | * stepped caused a page fault. We reset the current | |
586 | * kprobe and the rip points back to the probe address | |
587 | * and allow the page fault handler to continue as a | |
588 | * normal page fault. | |
589 | */ | |
590 | regs->rip = (unsigned long)cur->addr; | |
e7a510f9 | 591 | regs->eflags |= kcb->kprobe_old_rflags; |
c28f8966 PP |
592 | if (kcb->kprobe_status == KPROBE_REENTER) |
593 | restore_previous_kprobe(kcb); | |
594 | else | |
595 | reset_current_kprobe(); | |
1da177e4 | 596 | preempt_enable_no_resched(); |
c28f8966 PP |
597 | break; |
598 | case KPROBE_HIT_ACTIVE: | |
599 | case KPROBE_HIT_SSDONE: | |
600 | /* | |
601 | * We increment the nmissed count for accounting, | |
602 | * we can also use npre/npostfault count for accouting | |
603 | * these specific fault cases. | |
604 | */ | |
605 | kprobes_inc_nmissed_count(cur); | |
606 | ||
607 | /* | |
608 | * We come here because instructions in the pre/post | |
609 | * handler caused the page_fault, this could happen | |
610 | * if handler tries to access user space by | |
611 | * copy_from_user(), get_user() etc. Let the | |
612 | * user-specified handler try to fix it first. | |
613 | */ | |
614 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
615 | return 1; | |
616 | ||
617 | /* | |
618 | * In case the user-specified fault handler returned | |
619 | * zero, try to fix up. | |
620 | */ | |
621 | fixup = search_exception_tables(regs->rip); | |
622 | if (fixup) { | |
623 | regs->rip = fixup->fixup; | |
624 | return 1; | |
625 | } | |
626 | ||
627 | /* | |
628 | * fixup() could not handle it, | |
629 | * Let do_page_fault() fix it. | |
630 | */ | |
631 | break; | |
632 | default: | |
633 | break; | |
1da177e4 LT |
634 | } |
635 | return 0; | |
636 | } | |
637 | ||
638 | /* | |
639 | * Wrapper routine for handling exceptions. | |
640 | */ | |
0f2fbdcb PP |
641 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
642 | unsigned long val, void *data) | |
1da177e4 LT |
643 | { |
644 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
645 | int ret = NOTIFY_DONE; |
646 | ||
2326c770 | 647 | if (args->regs && user_mode(args->regs)) |
648 | return ret; | |
649 | ||
1da177e4 LT |
650 | switch (val) { |
651 | case DIE_INT3: | |
652 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 653 | ret = NOTIFY_STOP; |
1da177e4 LT |
654 | break; |
655 | case DIE_DEBUG: | |
656 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 657 | ret = NOTIFY_STOP; |
1da177e4 LT |
658 | break; |
659 | case DIE_GPF: | |
d217d545 AM |
660 | /* kprobe_running() needs smp_processor_id() */ |
661 | preempt_disable(); | |
1da177e4 LT |
662 | if (kprobe_running() && |
663 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 664 | ret = NOTIFY_STOP; |
d217d545 | 665 | preempt_enable(); |
1da177e4 LT |
666 | break; |
667 | default: | |
668 | break; | |
669 | } | |
66ff2d06 | 670 | return ret; |
1da177e4 LT |
671 | } |
672 | ||
0f2fbdcb | 673 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
674 | { |
675 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
676 | unsigned long addr; | |
e7a510f9 | 677 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 678 | |
e7a510f9 AM |
679 | kcb->jprobe_saved_regs = *regs; |
680 | kcb->jprobe_saved_rsp = (long *) regs->rsp; | |
681 | addr = (unsigned long)(kcb->jprobe_saved_rsp); | |
1da177e4 LT |
682 | /* |
683 | * As Linus pointed out, gcc assumes that the callee | |
684 | * owns the argument space and could overwrite it, e.g. | |
685 | * tailcall optimization. So, to be absolutely safe | |
686 | * we also save and restore enough stack bytes to cover | |
687 | * the argument area. | |
688 | */ | |
e7a510f9 AM |
689 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
690 | MIN_STACK_SIZE(addr)); | |
1da177e4 | 691 | regs->eflags &= ~IF_MASK; |
58dfe883 | 692 | trace_hardirqs_off(); |
1da177e4 LT |
693 | regs->rip = (unsigned long)(jp->entry); |
694 | return 1; | |
695 | } | |
696 | ||
0f2fbdcb | 697 | void __kprobes jprobe_return(void) |
1da177e4 | 698 | { |
e7a510f9 AM |
699 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
700 | ||
1da177e4 LT |
701 | asm volatile (" xchg %%rbx,%%rsp \n" |
702 | " int3 \n" | |
703 | " .globl jprobe_return_end \n" | |
704 | " jprobe_return_end: \n" | |
705 | " nop \n"::"b" | |
e7a510f9 | 706 | (kcb->jprobe_saved_rsp):"memory"); |
1da177e4 LT |
707 | } |
708 | ||
0f2fbdcb | 709 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 710 | { |
e7a510f9 | 711 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 712 | u8 *addr = (u8 *) (regs->rip - 1); |
e7a510f9 | 713 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp); |
1da177e4 LT |
714 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
715 | ||
716 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { | |
e7a510f9 | 717 | if ((long *)regs->rsp != kcb->jprobe_saved_rsp) { |
1da177e4 | 718 | struct pt_regs *saved_regs = |
e7a510f9 AM |
719 | container_of(kcb->jprobe_saved_rsp, |
720 | struct pt_regs, rsp); | |
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 | } |