Commit | Line | Data |
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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. | |
b94cce92 HN |
25 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
26 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi | |
27 | * <prasanna@in.ibm.com> added function-return probes. | |
1da177e4 LT |
28 | */ |
29 | ||
1da177e4 LT |
30 | #include <linux/kprobes.h> |
31 | #include <linux/ptrace.h> | |
1da177e4 | 32 | #include <linux/preempt.h> |
1eeb66a1 | 33 | #include <linux/kdebug.h> |
7e1048b1 | 34 | #include <asm/cacheflush.h> |
1da177e4 | 35 | #include <asm/desc.h> |
b4026513 | 36 | #include <asm/uaccess.h> |
19d36ccd | 37 | #include <asm/alternative.h> |
1da177e4 | 38 | |
1da177e4 LT |
39 | void jprobe_return_end(void); |
40 | ||
9a0e3a86 AM |
41 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
42 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
43 | ||
f438d914 MH |
44 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
45 | {"__switch_to", }, /* This function switches only current task, but | |
46 | doesn't switch kernel stack.*/ | |
47 | {NULL, NULL} /* Terminator */ | |
48 | }; | |
49 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
50 | ||
311ac88f | 51 | /* insert a jmp code */ |
34c37e18 | 52 | static __always_inline void set_jmp_op(void *from, void *to) |
311ac88f MH |
53 | { |
54 | struct __arch_jmp_op { | |
55 | char op; | |
56 | long raddr; | |
57 | } __attribute__((packed)) *jop; | |
58 | jop = (struct __arch_jmp_op *)from; | |
59 | jop->raddr = (long)(to) - ((long)(from) + 5); | |
60 | jop->op = RELATIVEJUMP_INSTRUCTION; | |
61 | } | |
62 | ||
63 | /* | |
64 | * returns non-zero if opcodes can be boosted. | |
65 | */ | |
585deaca | 66 | static __always_inline int can_boost(kprobe_opcode_t *opcodes) |
311ac88f | 67 | { |
585deaca MH |
68 | #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ |
69 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
70 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
71 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
72 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
73 | << (row % 32)) | |
74 | /* | |
75 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
76 | * Groups, and some special opcodes can not be boost. | |
77 | */ | |
78 | static const unsigned long twobyte_is_boostable[256 / 32] = { | |
79 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
80 | /* ------------------------------- */ | |
81 | W(0x00, 0,0,1,1,0,0,1,0,1,1,0,0,0,0,0,0)| /* 00 */ | |
82 | W(0x10, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 10 */ | |
83 | W(0x20, 1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0)| /* 20 */ | |
84 | W(0x30, 0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 30 */ | |
85 | W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 40 */ | |
86 | W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 50 */ | |
87 | W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,0,0,1,1)| /* 60 */ | |
88 | W(0x70, 0,0,0,0,1,1,1,1,0,0,0,0,0,0,1,1), /* 70 */ | |
89 | W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 80 */ | |
90 | W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1), /* 90 */ | |
91 | W(0xa0, 1,1,0,1,1,1,0,0,1,1,0,1,1,1,0,1)| /* a0 */ | |
92 | W(0xb0, 1,1,1,1,1,1,1,1,0,0,0,1,1,1,1,1), /* b0 */ | |
93 | W(0xc0, 1,1,0,0,0,0,0,0,1,1,1,1,1,1,1,1)| /* c0 */ | |
94 | W(0xd0, 0,1,1,1,0,1,0,0,1,1,0,1,1,1,0,1), /* d0 */ | |
95 | W(0xe0, 0,1,1,0,0,1,0,0,1,1,0,1,1,1,0,1)| /* e0 */ | |
96 | W(0xf0, 0,1,1,1,0,1,0,0,1,1,1,0,1,1,1,0) /* f0 */ | |
97 | /* ------------------------------- */ | |
98 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
99 | }; | |
100 | #undef W | |
101 | kprobe_opcode_t opcode; | |
102 | kprobe_opcode_t *orig_opcodes = opcodes; | |
103 | retry: | |
104 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
105 | return 0; | |
106 | opcode = *(opcodes++); | |
107 | ||
108 | /* 2nd-byte opcode */ | |
109 | if (opcode == 0x0f) { | |
110 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
111 | return 0; | |
112 | return test_bit(*opcodes, twobyte_is_boostable); | |
113 | } | |
114 | ||
115 | switch (opcode & 0xf0) { | |
116 | case 0x60: | |
117 | if (0x63 < opcode && opcode < 0x67) | |
118 | goto retry; /* prefixes */ | |
119 | /* can't boost Address-size override and bound */ | |
120 | return (opcode != 0x62 && opcode != 0x67); | |
311ac88f MH |
121 | case 0x70: |
122 | return 0; /* can't boost conditional jump */ | |
311ac88f | 123 | case 0xc0: |
585deaca MH |
124 | /* can't boost software-interruptions */ |
125 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
311ac88f MH |
126 | case 0xd0: |
127 | /* can boost AA* and XLAT */ | |
128 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
129 | case 0xe0: | |
585deaca MH |
130 | /* can boost in/out and absolute jmps */ |
131 | return ((opcode & 0x04) || opcode == 0xea); | |
311ac88f | 132 | case 0xf0: |
585deaca MH |
133 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) |
134 | goto retry; /* lock/rep(ne) prefix */ | |
311ac88f MH |
135 | /* clear and set flags can be boost */ |
136 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
137 | default: | |
585deaca MH |
138 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) |
139 | goto retry; /* prefixes */ | |
140 | /* can't boost CS override and call */ | |
141 | return (opcode != 0x2e && opcode != 0x9a); | |
311ac88f MH |
142 | } |
143 | } | |
144 | ||
1da177e4 LT |
145 | /* |
146 | * returns non-zero if opcode modifies the interrupt flag. | |
147 | */ | |
34c37e18 | 148 | static int __kprobes is_IF_modifier(kprobe_opcode_t opcode) |
1da177e4 LT |
149 | { |
150 | switch (opcode) { | |
151 | case 0xfa: /* cli */ | |
152 | case 0xfb: /* sti */ | |
153 | case 0xcf: /* iret/iretd */ | |
154 | case 0x9d: /* popf/popfd */ | |
155 | return 1; | |
156 | } | |
157 | return 0; | |
158 | } | |
159 | ||
3d97ae5b | 160 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 | 161 | { |
124d90be PP |
162 | /* insn: must be on special executable page on i386. */ |
163 | p->ainsn.insn = get_insn_slot(); | |
164 | if (!p->ainsn.insn) | |
165 | return -ENOMEM; | |
166 | ||
1da177e4 | 167 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
7e1048b1 | 168 | p->opcode = *p->addr; |
585deaca | 169 | if (can_boost(p->addr)) { |
311ac88f MH |
170 | p->ainsn.boostable = 0; |
171 | } else { | |
172 | p->ainsn.boostable = -1; | |
173 | } | |
49a2a1b8 | 174 | return 0; |
1da177e4 LT |
175 | } |
176 | ||
3d97ae5b | 177 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 178 | { |
19d36ccd | 179 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
180 | } |
181 | ||
3d97ae5b | 182 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 183 | { |
19d36ccd | 184 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
185 | } |
186 | ||
124d90be PP |
187 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
188 | { | |
7a7d1cf9 | 189 | mutex_lock(&kprobe_mutex); |
b4c6c34a | 190 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); |
7a7d1cf9 | 191 | mutex_unlock(&kprobe_mutex); |
124d90be PP |
192 | } |
193 | ||
34c37e18 | 194 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
417c8da6 | 195 | { |
9a0e3a86 AM |
196 | kcb->prev_kprobe.kp = kprobe_running(); |
197 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
198 | kcb->prev_kprobe.old_eflags = kcb->kprobe_old_eflags; | |
199 | kcb->prev_kprobe.saved_eflags = kcb->kprobe_saved_eflags; | |
417c8da6 PP |
200 | } |
201 | ||
34c37e18 | 202 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
417c8da6 | 203 | { |
9a0e3a86 AM |
204 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
205 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
206 | kcb->kprobe_old_eflags = kcb->prev_kprobe.old_eflags; | |
207 | kcb->kprobe_saved_eflags = kcb->prev_kprobe.saved_eflags; | |
417c8da6 PP |
208 | } |
209 | ||
34c37e18 | 210 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
9a0e3a86 | 211 | struct kprobe_ctlblk *kcb) |
417c8da6 | 212 | { |
9a0e3a86 AM |
213 | __get_cpu_var(current_kprobe) = p; |
214 | kcb->kprobe_saved_eflags = kcb->kprobe_old_eflags | |
65ea5b03 | 215 | = (regs->flags & (TF_MASK | IF_MASK)); |
417c8da6 | 216 | if (is_IF_modifier(p->opcode)) |
9a0e3a86 | 217 | kcb->kprobe_saved_eflags &= ~IF_MASK; |
417c8da6 PP |
218 | } |
219 | ||
1ecc798c RM |
220 | static __always_inline void clear_btf(void) |
221 | { | |
222 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
223 | wrmsr(MSR_IA32_DEBUGCTLMSR, 0, 0); | |
224 | } | |
225 | ||
226 | static __always_inline void restore_btf(void) | |
227 | { | |
228 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
229 | wrmsr(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr, 0); | |
230 | } | |
231 | ||
34c37e18 | 232 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 233 | { |
1ecc798c | 234 | clear_btf(); |
65ea5b03 PA |
235 | regs->flags |= TF_MASK; |
236 | regs->flags &= ~IF_MASK; | |
1da177e4 LT |
237 | /*single step inline if the instruction is an int3*/ |
238 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
65ea5b03 | 239 | regs->ip = (unsigned long)p->addr; |
1da177e4 | 240 | else |
65ea5b03 | 241 | regs->ip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
242 | } |
243 | ||
991a51d8 | 244 | /* Called with kretprobe_lock held */ |
4c4308cb | 245 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
3d97ae5b | 246 | struct pt_regs *regs) |
b94cce92 | 247 | { |
65ea5b03 | 248 | unsigned long *sara = (unsigned long *)®s->sp; |
4bdbd37f | 249 | |
4c4308cb | 250 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
62c27be0 | 251 | |
4c4308cb CH |
252 | /* Replace the return addr with trampoline addr */ |
253 | *sara = (unsigned long) &kretprobe_trampoline; | |
b94cce92 HN |
254 | } |
255 | ||
1da177e4 LT |
256 | /* |
257 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
258 | * remain disabled thorough out this function. | |
259 | */ | |
3d97ae5b | 260 | static int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
261 | { |
262 | struct kprobe *p; | |
263 | int ret = 0; | |
2326c770 | 264 | kprobe_opcode_t *addr; |
d217d545 AM |
265 | struct kprobe_ctlblk *kcb; |
266 | ||
65ea5b03 | 267 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
2326c770 | 268 | |
d217d545 AM |
269 | /* |
270 | * We don't want to be preempted for the entire | |
271 | * duration of kprobe processing | |
272 | */ | |
273 | preempt_disable(); | |
274 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 275 | |
1da177e4 LT |
276 | /* Check we're not actually recursing */ |
277 | if (kprobe_running()) { | |
1da177e4 LT |
278 | p = get_kprobe(addr); |
279 | if (p) { | |
9a0e3a86 | 280 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 281 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
65ea5b03 PA |
282 | regs->flags &= ~TF_MASK; |
283 | regs->flags |= kcb->kprobe_saved_eflags; | |
1da177e4 LT |
284 | goto no_kprobe; |
285 | } | |
417c8da6 PP |
286 | /* We have reentered the kprobe_handler(), since |
287 | * another probe was hit while within the handler. | |
288 | * We here save the original kprobes variables and | |
289 | * just single step on the instruction of the new probe | |
290 | * without calling any user handlers. | |
291 | */ | |
9a0e3a86 AM |
292 | save_previous_kprobe(kcb); |
293 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 294 | kprobes_inc_nmissed_count(p); |
417c8da6 | 295 | prepare_singlestep(p, regs); |
9a0e3a86 | 296 | kcb->kprobe_status = KPROBE_REENTER; |
417c8da6 | 297 | return 1; |
1da177e4 | 298 | } else { |
eb3a7292 KA |
299 | if (*addr != BREAKPOINT_INSTRUCTION) { |
300 | /* The breakpoint instruction was removed by | |
301 | * another cpu right after we hit, no further | |
302 | * handling of this interrupt is appropriate | |
303 | */ | |
65ea5b03 | 304 | regs->ip -= sizeof(kprobe_opcode_t); |
eb3a7292 KA |
305 | ret = 1; |
306 | goto no_kprobe; | |
307 | } | |
9a0e3a86 | 308 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
309 | if (p->break_handler && p->break_handler(p, regs)) { |
310 | goto ss_probe; | |
311 | } | |
312 | } | |
1da177e4 LT |
313 | goto no_kprobe; |
314 | } | |
315 | ||
1da177e4 LT |
316 | p = get_kprobe(addr); |
317 | if (!p) { | |
1da177e4 LT |
318 | if (*addr != BREAKPOINT_INSTRUCTION) { |
319 | /* | |
320 | * The breakpoint instruction was removed right | |
321 | * after we hit it. Another cpu has removed | |
322 | * either a probepoint or a debugger breakpoint | |
323 | * at this address. In either case, no further | |
324 | * handling of this interrupt is appropriate. | |
bce06494 JK |
325 | * Back up over the (now missing) int3 and run |
326 | * the original instruction. | |
1da177e4 | 327 | */ |
65ea5b03 | 328 | regs->ip -= sizeof(kprobe_opcode_t); |
1da177e4 LT |
329 | ret = 1; |
330 | } | |
331 | /* Not one of ours: let kernel handle it */ | |
332 | goto no_kprobe; | |
333 | } | |
334 | ||
9a0e3a86 AM |
335 | set_current_kprobe(p, regs, kcb); |
336 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
337 | |
338 | if (p->pre_handler && p->pre_handler(p, regs)) | |
339 | /* handler has already set things up, so skip ss setup */ | |
340 | return 1; | |
341 | ||
36721656 | 342 | ss_probe: |
b4c6c34a | 343 | #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) |
c39df470 | 344 | if (p->ainsn.boostable == 1 && !p->post_handler){ |
311ac88f MH |
345 | /* Boost up -- we can execute copied instructions directly */ |
346 | reset_current_kprobe(); | |
65ea5b03 | 347 | regs->ip = (unsigned long)p->ainsn.insn; |
311ac88f MH |
348 | preempt_enable_no_resched(); |
349 | return 1; | |
350 | } | |
c39df470 | 351 | #endif |
1da177e4 | 352 | prepare_singlestep(p, regs); |
9a0e3a86 | 353 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
354 | return 1; |
355 | ||
356 | no_kprobe: | |
d217d545 | 357 | preempt_enable_no_resched(); |
1da177e4 LT |
358 | return ret; |
359 | } | |
360 | ||
b94cce92 HN |
361 | /* |
362 | * For function-return probes, init_kprobes() establishes a probepoint | |
363 | * here. When a retprobed function returns, this probe is hit and | |
364 | * trampoline_probe_handler() runs, calling the kretprobe's handler. | |
365 | */ | |
c9becf58 | 366 | void __kprobes kretprobe_trampoline_holder(void) |
b94cce92 | 367 | { |
c9becf58 | 368 | asm volatile ( ".global kretprobe_trampoline\n" |
62c27be0 | 369 | "kretprobe_trampoline: \n" |
c9becf58 | 370 | " pushf\n" |
65ea5b03 | 371 | /* skip cs, ip, orig_ax */ |
8bdc052e | 372 | " subl $12, %esp\n" |
464d1a78 | 373 | " pushl %fs\n" |
8bdc052e MH |
374 | " pushl %ds\n" |
375 | " pushl %es\n" | |
c9becf58 MH |
376 | " pushl %eax\n" |
377 | " pushl %ebp\n" | |
378 | " pushl %edi\n" | |
379 | " pushl %esi\n" | |
380 | " pushl %edx\n" | |
381 | " pushl %ecx\n" | |
382 | " pushl %ebx\n" | |
383 | " movl %esp, %eax\n" | |
384 | " call trampoline_handler\n" | |
65ea5b03 | 385 | /* move flags to cs */ |
8bdc052e MH |
386 | " movl 52(%esp), %edx\n" |
387 | " movl %edx, 48(%esp)\n" | |
65ea5b03 | 388 | /* save true return address on flags */ |
8bdc052e | 389 | " movl %eax, 52(%esp)\n" |
c9becf58 MH |
390 | " popl %ebx\n" |
391 | " popl %ecx\n" | |
392 | " popl %edx\n" | |
393 | " popl %esi\n" | |
394 | " popl %edi\n" | |
395 | " popl %ebp\n" | |
396 | " popl %eax\n" | |
65ea5b03 | 397 | /* skip ip, orig_ax, es, ds, fs */ |
8bdc052e | 398 | " addl $20, %esp\n" |
c9becf58 MH |
399 | " popf\n" |
400 | " ret\n"); | |
401 | } | |
b94cce92 HN |
402 | |
403 | /* | |
c9becf58 | 404 | * Called from kretprobe_trampoline |
b94cce92 | 405 | */ |
c9becf58 | 406 | fastcall void *__kprobes trampoline_handler(struct pt_regs *regs) |
b94cce92 | 407 | { |
62c27be0 | 408 | struct kretprobe_instance *ri = NULL; |
99219a3f | 409 | struct hlist_head *head, empty_rp; |
62c27be0 | 410 | struct hlist_node *node, *tmp; |
991a51d8 | 411 | unsigned long flags, orig_ret_address = 0; |
4bdbd37f | 412 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
b94cce92 | 413 | |
99219a3f | 414 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 415 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 416 | head = kretprobe_inst_table_head(current); |
8bdc052e | 417 | /* fixup registers */ |
65ea5b03 PA |
418 | regs->cs = __KERNEL_CS | get_kernel_rpl(); |
419 | regs->ip = trampoline_address; | |
420 | regs->orig_ax = 0xffffffff; | |
b94cce92 | 421 | |
4bdbd37f RL |
422 | /* |
423 | * It is possible to have multiple instances associated with a given | |
424 | * task either because an multiple functions in the call path | |
425 | * have a return probe installed on them, and/or more then one return | |
426 | * return probe was registered for a target function. | |
427 | * | |
428 | * We can handle this because: | |
429 | * - instances are always inserted at the head of the list | |
430 | * - when multiple return probes are registered for the same | |
62c27be0 | 431 | * function, the first instance's ret_addr will point to the |
4bdbd37f RL |
432 | * real return address, and all the rest will point to |
433 | * kretprobe_trampoline | |
434 | */ | |
435 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 436 | if (ri->task != current) |
4bdbd37f | 437 | /* another task is sharing our hash bucket */ |
62c27be0 | 438 | continue; |
4bdbd37f | 439 | |
c9becf58 MH |
440 | if (ri->rp && ri->rp->handler){ |
441 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
8bdc052e | 442 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
4bdbd37f | 443 | ri->rp->handler(ri, regs); |
c9becf58 MH |
444 | __get_cpu_var(current_kprobe) = NULL; |
445 | } | |
4bdbd37f RL |
446 | |
447 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 448 | recycle_rp_inst(ri, &empty_rp); |
4bdbd37f RL |
449 | |
450 | if (orig_ret_address != trampoline_address) | |
451 | /* | |
452 | * This is the real return address. Any other | |
453 | * instances associated with this task are for | |
454 | * other calls deeper on the call stack | |
455 | */ | |
456 | break; | |
b94cce92 | 457 | } |
4bdbd37f | 458 | |
0f95b7fc | 459 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
991a51d8 | 460 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
4bdbd37f | 461 | |
99219a3f | 462 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
463 | hlist_del(&ri->hlist); | |
464 | kfree(ri); | |
465 | } | |
c9becf58 | 466 | return (void*)orig_ret_address; |
b94cce92 HN |
467 | } |
468 | ||
1da177e4 LT |
469 | /* |
470 | * Called after single-stepping. p->addr is the address of the | |
471 | * instruction whose first byte has been replaced by the "int 3" | |
472 | * instruction. To avoid the SMP problems that can occur when we | |
473 | * temporarily put back the original opcode to single-step, we | |
474 | * single-stepped a copy of the instruction. The address of this | |
475 | * copy is p->ainsn.insn. | |
476 | * | |
477 | * This function prepares to return from the post-single-step | |
478 | * interrupt. We have to fix up the stack as follows: | |
479 | * | |
480 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 481 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
482 | * it relative to the original instruction. |
483 | * | |
484 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 485 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
486 | * |
487 | * 2) If the single-stepped instruction was a call, the return address | |
488 | * that is atop the stack is the address following the copied instruction. | |
489 | * We need to make it the address following the original instruction. | |
311ac88f MH |
490 | * |
491 | * This function also checks instruction size for preparing direct execution. | |
1da177e4 | 492 | */ |
9a0e3a86 AM |
493 | static void __kprobes resume_execution(struct kprobe *p, |
494 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 495 | { |
65ea5b03 | 496 | unsigned long *tos = (unsigned long *)®s->sp; |
124d90be | 497 | unsigned long copy_eip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
498 | unsigned long orig_eip = (unsigned long)p->addr; |
499 | ||
65ea5b03 | 500 | regs->flags &= ~TF_MASK; |
1da177e4 LT |
501 | switch (p->ainsn.insn[0]) { |
502 | case 0x9c: /* pushfl */ | |
503 | *tos &= ~(TF_MASK | IF_MASK); | |
9a0e3a86 | 504 | *tos |= kcb->kprobe_old_eflags; |
1da177e4 | 505 | break; |
bcff5cd6 MH |
506 | case 0xc2: /* iret/ret/lret */ |
507 | case 0xc3: | |
0b9e2cac | 508 | case 0xca: |
bcff5cd6 MH |
509 | case 0xcb: |
510 | case 0xcf: | |
65ea5b03 PA |
511 | case 0xea: /* jmp absolute -- ip is correct */ |
512 | /* ip is already adjusted, no more changes required */ | |
311ac88f | 513 | p->ainsn.boostable = 1; |
b50ea74c | 514 | goto no_change; |
1da177e4 LT |
515 | case 0xe8: /* call relative - Fix return addr */ |
516 | *tos = orig_eip + (*tos - copy_eip); | |
517 | break; | |
bcff5cd6 MH |
518 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
519 | *tos = orig_eip + (*tos - copy_eip); | |
520 | goto no_change; | |
1da177e4 LT |
521 | case 0xff: |
522 | if ((p->ainsn.insn[1] & 0x30) == 0x10) { | |
311ac88f | 523 | /* |
bcff5cd6 | 524 | * call absolute, indirect |
65ea5b03 | 525 | * Fix return addr; ip is correct. |
311ac88f MH |
526 | * But this is not boostable |
527 | */ | |
1da177e4 | 528 | *tos = orig_eip + (*tos - copy_eip); |
b50ea74c | 529 | goto no_change; |
1da177e4 LT |
530 | } else if (((p->ainsn.insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
531 | ((p->ainsn.insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ | |
65ea5b03 | 532 | /* ip is correct. And this is boostable */ |
311ac88f | 533 | p->ainsn.boostable = 1; |
b50ea74c | 534 | goto no_change; |
1da177e4 | 535 | } |
1da177e4 LT |
536 | default: |
537 | break; | |
538 | } | |
539 | ||
311ac88f | 540 | if (p->ainsn.boostable == 0) { |
65ea5b03 PA |
541 | if ((regs->ip > copy_eip) && |
542 | (regs->ip - copy_eip) + 5 < MAX_INSN_SIZE) { | |
311ac88f MH |
543 | /* |
544 | * These instructions can be executed directly if it | |
545 | * jumps back to correct address. | |
546 | */ | |
65ea5b03 PA |
547 | set_jmp_op((void *)regs->ip, |
548 | (void *)orig_eip + (regs->ip - copy_eip)); | |
311ac88f MH |
549 | p->ainsn.boostable = 1; |
550 | } else { | |
551 | p->ainsn.boostable = -1; | |
552 | } | |
553 | } | |
554 | ||
65ea5b03 | 555 | regs->ip = orig_eip + (regs->ip - copy_eip); |
b50ea74c MH |
556 | |
557 | no_change: | |
1ecc798c RM |
558 | restore_btf(); |
559 | ||
b50ea74c | 560 | return; |
1da177e4 LT |
561 | } |
562 | ||
563 | /* | |
564 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
991a51d8 | 565 | * remain disabled thoroughout this function. |
1da177e4 | 566 | */ |
34c37e18 | 567 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 568 | { |
9a0e3a86 AM |
569 | struct kprobe *cur = kprobe_running(); |
570 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
571 | ||
572 | if (!cur) | |
1da177e4 LT |
573 | return 0; |
574 | ||
9a0e3a86 AM |
575 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
576 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
577 | cur->post_handler(cur, regs, 0); | |
417c8da6 | 578 | } |
1da177e4 | 579 | |
9a0e3a86 | 580 | resume_execution(cur, regs, kcb); |
65ea5b03 PA |
581 | regs->flags |= kcb->kprobe_saved_eflags; |
582 | trace_hardirqs_fixup_flags(regs->flags); | |
1da177e4 | 583 | |
417c8da6 | 584 | /*Restore back the original saved kprobes variables and continue. */ |
9a0e3a86 AM |
585 | if (kcb->kprobe_status == KPROBE_REENTER) { |
586 | restore_previous_kprobe(kcb); | |
417c8da6 PP |
587 | goto out; |
588 | } | |
9a0e3a86 | 589 | reset_current_kprobe(); |
417c8da6 | 590 | out: |
1da177e4 LT |
591 | preempt_enable_no_resched(); |
592 | ||
593 | /* | |
65ea5b03 | 594 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
595 | * will have TF set, in which case, continue the remaining processing |
596 | * of do_debug, as if this is not a probe hit. | |
597 | */ | |
65ea5b03 | 598 | if (regs->flags & TF_MASK) |
1da177e4 LT |
599 | return 0; |
600 | ||
601 | return 1; | |
602 | } | |
603 | ||
74a0b576 | 604 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 605 | { |
9a0e3a86 AM |
606 | struct kprobe *cur = kprobe_running(); |
607 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
608 | ||
b4026513 PP |
609 | switch(kcb->kprobe_status) { |
610 | case KPROBE_HIT_SS: | |
611 | case KPROBE_REENTER: | |
612 | /* | |
613 | * We are here because the instruction being single | |
614 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 615 | * kprobe and the ip points back to the probe address |
b4026513 PP |
616 | * and allow the page fault handler to continue as a |
617 | * normal page fault. | |
618 | */ | |
65ea5b03 PA |
619 | regs->ip = (unsigned long)cur->addr; |
620 | regs->flags |= kcb->kprobe_old_eflags; | |
b4026513 PP |
621 | if (kcb->kprobe_status == KPROBE_REENTER) |
622 | restore_previous_kprobe(kcb); | |
623 | else | |
624 | reset_current_kprobe(); | |
1da177e4 | 625 | preempt_enable_no_resched(); |
b4026513 PP |
626 | break; |
627 | case KPROBE_HIT_ACTIVE: | |
628 | case KPROBE_HIT_SSDONE: | |
629 | /* | |
630 | * We increment the nmissed count for accounting, | |
631 | * we can also use npre/npostfault count for accouting | |
632 | * these specific fault cases. | |
633 | */ | |
634 | kprobes_inc_nmissed_count(cur); | |
635 | ||
636 | /* | |
637 | * We come here because instructions in the pre/post | |
638 | * handler caused the page_fault, this could happen | |
639 | * if handler tries to access user space by | |
640 | * copy_from_user(), get_user() etc. Let the | |
641 | * user-specified handler try to fix it first. | |
642 | */ | |
643 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
644 | return 1; | |
645 | ||
646 | /* | |
647 | * In case the user-specified fault handler returned | |
648 | * zero, try to fix up. | |
649 | */ | |
650 | if (fixup_exception(regs)) | |
651 | return 1; | |
652 | ||
653 | /* | |
654 | * fixup_exception() could not handle it, | |
655 | * Let do_page_fault() fix it. | |
656 | */ | |
657 | break; | |
658 | default: | |
659 | break; | |
1da177e4 LT |
660 | } |
661 | return 0; | |
662 | } | |
663 | ||
664 | /* | |
665 | * Wrapper routine to for handling exceptions. | |
666 | */ | |
3d97ae5b PP |
667 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
668 | unsigned long val, void *data) | |
1da177e4 LT |
669 | { |
670 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
671 | int ret = NOTIFY_DONE; |
672 | ||
64445416 | 673 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 674 | return ret; |
675 | ||
1da177e4 LT |
676 | switch (val) { |
677 | case DIE_INT3: | |
678 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 679 | ret = NOTIFY_STOP; |
1da177e4 LT |
680 | break; |
681 | case DIE_DEBUG: | |
682 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 683 | ret = NOTIFY_STOP; |
1da177e4 LT |
684 | break; |
685 | case DIE_GPF: | |
d217d545 AM |
686 | /* kprobe_running() needs smp_processor_id() */ |
687 | preempt_disable(); | |
1da177e4 LT |
688 | if (kprobe_running() && |
689 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 690 | ret = NOTIFY_STOP; |
d217d545 | 691 | preempt_enable(); |
1da177e4 LT |
692 | break; |
693 | default: | |
694 | break; | |
695 | } | |
66ff2d06 | 696 | return ret; |
1da177e4 LT |
697 | } |
698 | ||
3d97ae5b | 699 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
700 | { |
701 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
702 | unsigned long addr; | |
9a0e3a86 | 703 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 704 | |
9a0e3a86 | 705 | kcb->jprobe_saved_regs = *regs; |
65ea5b03 | 706 | kcb->jprobe_saved_esp = ®s->sp; |
9a0e3a86 | 707 | addr = (unsigned long)(kcb->jprobe_saved_esp); |
1da177e4 LT |
708 | |
709 | /* | |
710 | * TBD: As Linus pointed out, gcc assumes that the callee | |
711 | * owns the argument space and could overwrite it, e.g. | |
712 | * tailcall optimization. So, to be absolutely safe | |
713 | * we also save and restore enough stack bytes to cover | |
714 | * the argument area. | |
715 | */ | |
9a0e3a86 AM |
716 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
717 | MIN_STACK_SIZE(addr)); | |
65ea5b03 | 718 | regs->flags &= ~IF_MASK; |
58dfe883 | 719 | trace_hardirqs_off(); |
65ea5b03 | 720 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
721 | return 1; |
722 | } | |
723 | ||
3d97ae5b | 724 | void __kprobes jprobe_return(void) |
1da177e4 | 725 | { |
9a0e3a86 AM |
726 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
727 | ||
1da177e4 LT |
728 | asm volatile (" xchgl %%ebx,%%esp \n" |
729 | " int3 \n" | |
730 | " .globl jprobe_return_end \n" | |
731 | " jprobe_return_end: \n" | |
732 | " nop \n"::"b" | |
9a0e3a86 | 733 | (kcb->jprobe_saved_esp):"memory"); |
1da177e4 LT |
734 | } |
735 | ||
3d97ae5b | 736 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 737 | { |
9a0e3a86 | 738 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 739 | u8 *addr = (u8 *) (regs->ip - 1); |
9a0e3a86 | 740 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_esp); |
1da177e4 LT |
741 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
742 | ||
743 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { | |
65ea5b03 | 744 | if (®s->sp != kcb->jprobe_saved_esp) { |
29b6cd79 | 745 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
65ea5b03 PA |
746 | printk("current sp %p does not match saved sp %p\n", |
747 | ®s->sp, kcb->jprobe_saved_esp); | |
1da177e4 LT |
748 | printk("Saved registers for jprobe %p\n", jp); |
749 | show_registers(saved_regs); | |
750 | printk("Current registers\n"); | |
751 | show_registers(regs); | |
752 | BUG(); | |
753 | } | |
9a0e3a86 AM |
754 | *regs = kcb->jprobe_saved_regs; |
755 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, | |
1da177e4 | 756 | MIN_STACK_SIZE(stack_addr)); |
d217d545 | 757 | preempt_enable_no_resched(); |
1da177e4 LT |
758 | return 1; |
759 | } | |
760 | return 0; | |
761 | } | |
4bdbd37f | 762 | |
bf8f6e5b AM |
763 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) |
764 | { | |
765 | return 0; | |
766 | } | |
767 | ||
6772926b | 768 | int __init arch_init_kprobes(void) |
4bdbd37f | 769 | { |
c9becf58 | 770 | return 0; |
4bdbd37f | 771 | } |