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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. | |
d6be29b8 MH |
25 | * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
26 | * <prasanna@in.ibm.com> adapted for x86_64 from i386. | |
1da177e4 LT |
27 | * 2005-Mar Roland McGrath <roland@redhat.com> |
28 | * Fixed to handle %rip-relative addressing mode correctly. | |
d6be29b8 MH |
29 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
30 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi | |
31 | * <prasanna@in.ibm.com> added function-return probes. | |
32 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> | |
33 | * Added function return probes functionality | |
34 | * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added | |
35 | * kprobe-booster and kretprobe-booster for i386. | |
da07ab03 MH |
36 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster |
37 | * and kretprobe-booster for x86-64 | |
d6be29b8 MH |
38 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven |
39 | * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> | |
40 | * unified x86 kprobes code. | |
1da177e4 LT |
41 | */ |
42 | ||
1da177e4 LT |
43 | #include <linux/kprobes.h> |
44 | #include <linux/ptrace.h> | |
1da177e4 LT |
45 | #include <linux/string.h> |
46 | #include <linux/slab.h> | |
b506a9d0 | 47 | #include <linux/hardirq.h> |
1da177e4 | 48 | #include <linux/preempt.h> |
c28f8966 | 49 | #include <linux/module.h> |
1eeb66a1 | 50 | #include <linux/kdebug.h> |
b46b3d70 | 51 | #include <linux/kallsyms.h> |
9ec4b1f3 | 52 | |
8533bbe9 MH |
53 | #include <asm/cacheflush.h> |
54 | #include <asm/desc.h> | |
1da177e4 | 55 | #include <asm/pgtable.h> |
c28f8966 | 56 | #include <asm/uaccess.h> |
19d36ccd | 57 | #include <asm/alternative.h> |
b46b3d70 | 58 | #include <asm/insn.h> |
62edab90 | 59 | #include <asm/debugreg.h> |
1da177e4 | 60 | |
1da177e4 LT |
61 | void jprobe_return_end(void); |
62 | ||
e7a510f9 AM |
63 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
64 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 65 | |
98272ed0 | 66 | #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) |
8533bbe9 MH |
67 | |
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 boost. | |
77 | */ | |
78 | static const u32 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 | }; | |
8533bbe9 MH |
100 | #undef W |
101 | ||
f438d914 MH |
102 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
103 | {"__switch_to", }, /* This function switches only current task, but | |
104 | doesn't switch kernel stack.*/ | |
105 | {NULL, NULL} /* Terminator */ | |
106 | }; | |
107 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
108 | ||
aa470140 | 109 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
e7b5e11e | 110 | static void __kprobes set_jmp_op(void *from, void *to) |
aa470140 MH |
111 | { |
112 | struct __arch_jmp_op { | |
113 | char op; | |
114 | s32 raddr; | |
115 | } __attribute__((packed)) * jop; | |
116 | jop = (struct __arch_jmp_op *)from; | |
117 | jop->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
d498f763 | 118 | jop->op = RELATIVEJUMP_OPCODE; |
aa470140 MH |
119 | } |
120 | ||
9930927f HH |
121 | /* |
122 | * Check for the REX prefix which can only exist on X86_64 | |
123 | * X86_32 always returns 0 | |
124 | */ | |
125 | static int __kprobes is_REX_prefix(kprobe_opcode_t *insn) | |
126 | { | |
127 | #ifdef CONFIG_X86_64 | |
128 | if ((*insn & 0xf0) == 0x40) | |
129 | return 1; | |
130 | #endif | |
131 | return 0; | |
132 | } | |
133 | ||
aa470140 | 134 | /* |
d6be29b8 MH |
135 | * Returns non-zero if opcode is boostable. |
136 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 137 | */ |
e7b5e11e | 138 | static int __kprobes can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 139 | { |
aa470140 MH |
140 | kprobe_opcode_t opcode; |
141 | kprobe_opcode_t *orig_opcodes = opcodes; | |
142 | ||
cde5edbd | 143 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
144 | return 0; /* Page fault may occur on this address. */ |
145 | ||
aa470140 MH |
146 | retry: |
147 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
148 | return 0; | |
149 | opcode = *(opcodes++); | |
150 | ||
151 | /* 2nd-byte opcode */ | |
152 | if (opcode == 0x0f) { | |
153 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
154 | return 0; | |
8533bbe9 MH |
155 | return test_bit(*opcodes, |
156 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
157 | } |
158 | ||
159 | switch (opcode & 0xf0) { | |
d6be29b8 | 160 | #ifdef CONFIG_X86_64 |
aa470140 MH |
161 | case 0x40: |
162 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 163 | #endif |
aa470140 MH |
164 | case 0x60: |
165 | if (0x63 < opcode && opcode < 0x67) | |
166 | goto retry; /* prefixes */ | |
167 | /* can't boost Address-size override and bound */ | |
168 | return (opcode != 0x62 && opcode != 0x67); | |
169 | case 0x70: | |
170 | return 0; /* can't boost conditional jump */ | |
171 | case 0xc0: | |
172 | /* can't boost software-interruptions */ | |
173 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
174 | case 0xd0: | |
175 | /* can boost AA* and XLAT */ | |
176 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
177 | case 0xe0: | |
178 | /* can boost in/out and absolute jmps */ | |
179 | return ((opcode & 0x04) || opcode == 0xea); | |
180 | case 0xf0: | |
181 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
182 | goto retry; /* lock/rep(ne) prefix */ | |
183 | /* clear and set flags are boostable */ | |
184 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
185 | default: | |
186 | /* segment override prefixes are boostable */ | |
187 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
188 | goto retry; /* prefixes */ | |
189 | /* CS override prefix and call are not boostable */ | |
190 | return (opcode != 0x2e && opcode != 0x9a); | |
191 | } | |
192 | } | |
193 | ||
b46b3d70 MH |
194 | /* Recover the probed instruction at addr for further analysis. */ |
195 | static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) | |
196 | { | |
197 | struct kprobe *kp; | |
198 | kp = get_kprobe((void *)addr); | |
199 | if (!kp) | |
200 | return -EINVAL; | |
201 | ||
202 | /* | |
203 | * Basically, kp->ainsn.insn has an original instruction. | |
204 | * However, RIP-relative instruction can not do single-stepping | |
205 | * at different place, fix_riprel() tweaks the displacement of | |
206 | * that instruction. In that case, we can't recover the instruction | |
207 | * from the kp->ainsn.insn. | |
208 | * | |
209 | * On the other hand, kp->opcode has a copy of the first byte of | |
210 | * the probed instruction, which is overwritten by int3. And | |
211 | * the instruction at kp->addr is not modified by kprobes except | |
212 | * for the first byte, we can recover the original instruction | |
213 | * from it and kp->opcode. | |
214 | */ | |
215 | memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
216 | buf[0] = kp->opcode; | |
217 | return 0; | |
218 | } | |
219 | ||
220 | /* Dummy buffers for kallsyms_lookup */ | |
221 | static char __dummy_buf[KSYM_NAME_LEN]; | |
222 | ||
223 | /* Check if paddr is at an instruction boundary */ | |
224 | static int __kprobes can_probe(unsigned long paddr) | |
225 | { | |
226 | int ret; | |
227 | unsigned long addr, offset = 0; | |
228 | struct insn insn; | |
229 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
230 | ||
231 | if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf)) | |
232 | return 0; | |
233 | ||
234 | /* Decode instructions */ | |
235 | addr = paddr - offset; | |
236 | while (addr < paddr) { | |
237 | kernel_insn_init(&insn, (void *)addr); | |
238 | insn_get_opcode(&insn); | |
239 | ||
240 | /* | |
241 | * Check if the instruction has been modified by another | |
242 | * kprobe, in which case we replace the breakpoint by the | |
243 | * original instruction in our buffer. | |
244 | */ | |
245 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
246 | ret = recover_probed_instruction(buf, addr); | |
247 | if (ret) | |
248 | /* | |
249 | * Another debugging subsystem might insert | |
250 | * this breakpoint. In that case, we can't | |
251 | * recover it. | |
252 | */ | |
253 | return 0; | |
254 | kernel_insn_init(&insn, buf); | |
255 | } | |
256 | insn_get_length(&insn); | |
257 | addr += insn.length; | |
258 | } | |
259 | ||
260 | return (addr == paddr); | |
261 | } | |
262 | ||
1da177e4 | 263 | /* |
d6be29b8 | 264 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 265 | */ |
8645419c | 266 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
267 | { |
268 | switch (*insn) { | |
269 | case 0xfa: /* cli */ | |
270 | case 0xfb: /* sti */ | |
271 | case 0xcf: /* iret/iretd */ | |
272 | case 0x9d: /* popf/popfd */ | |
273 | return 1; | |
274 | } | |
9930927f | 275 | |
8533bbe9 | 276 | /* |
9930927f | 277 | * on X86_64, 0x40-0x4f are REX prefixes so we need to look |
8533bbe9 MH |
278 | * at the next byte instead.. but of course not recurse infinitely |
279 | */ | |
9930927f | 280 | if (is_REX_prefix(insn)) |
8533bbe9 | 281 | return is_IF_modifier(++insn); |
9930927f | 282 | |
1da177e4 LT |
283 | return 0; |
284 | } | |
285 | ||
286 | /* | |
8533bbe9 MH |
287 | * Adjust the displacement if the instruction uses the %rip-relative |
288 | * addressing mode. | |
aa470140 | 289 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 290 | * If not, return null. |
31f80e45 | 291 | * Only applicable to 64-bit x86. |
1da177e4 | 292 | */ |
8533bbe9 | 293 | static void __kprobes fix_riprel(struct kprobe *p) |
1da177e4 | 294 | { |
31f80e45 | 295 | #ifdef CONFIG_X86_64 |
89ae465b MH |
296 | struct insn insn; |
297 | kernel_insn_init(&insn, p->ainsn.insn); | |
1da177e4 | 298 | |
89ae465b MH |
299 | if (insn_rip_relative(&insn)) { |
300 | s64 newdisp; | |
301 | u8 *disp; | |
302 | insn_get_displacement(&insn); | |
303 | /* | |
304 | * The copied instruction uses the %rip-relative addressing | |
305 | * mode. Adjust the displacement for the difference between | |
306 | * the original location of this instruction and the location | |
307 | * of the copy that will actually be run. The tricky bit here | |
308 | * is making sure that the sign extension happens correctly in | |
309 | * this calculation, since we need a signed 32-bit result to | |
310 | * be sign-extended to 64 bits when it's added to the %rip | |
311 | * value and yield the same 64-bit result that the sign- | |
312 | * extension of the original signed 32-bit displacement would | |
313 | * have given. | |
314 | */ | |
315 | newdisp = (u8 *) p->addr + (s64) insn.displacement.value - | |
316 | (u8 *) p->ainsn.insn; | |
317 | BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */ | |
318 | disp = (u8 *) p->ainsn.insn + insn_offset_displacement(&insn); | |
319 | *(s32 *) disp = (s32) newdisp; | |
1da177e4 | 320 | } |
d6be29b8 | 321 | #endif |
31f80e45 | 322 | } |
1da177e4 | 323 | |
f709b122 | 324 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 325 | { |
8533bbe9 | 326 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
31f80e45 | 327 | |
8533bbe9 | 328 | fix_riprel(p); |
31f80e45 | 329 | |
8533bbe9 | 330 | if (can_boost(p->addr)) |
aa470140 | 331 | p->ainsn.boostable = 0; |
8533bbe9 | 332 | else |
aa470140 | 333 | p->ainsn.boostable = -1; |
8533bbe9 | 334 | |
7e1048b1 | 335 | p->opcode = *p->addr; |
1da177e4 LT |
336 | } |
337 | ||
8533bbe9 MH |
338 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
339 | { | |
4554dbcb MH |
340 | if (alternatives_text_reserved(p->addr, p->addr)) |
341 | return -EINVAL; | |
342 | ||
b46b3d70 MH |
343 | if (!can_probe((unsigned long)p->addr)) |
344 | return -EILSEQ; | |
8533bbe9 MH |
345 | /* insn: must be on special executable page on x86. */ |
346 | p->ainsn.insn = get_insn_slot(); | |
347 | if (!p->ainsn.insn) | |
348 | return -ENOMEM; | |
349 | arch_copy_kprobe(p); | |
350 | return 0; | |
351 | } | |
352 | ||
0f2fbdcb | 353 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 354 | { |
19d36ccd | 355 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
356 | } |
357 | ||
0f2fbdcb | 358 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 359 | { |
19d36ccd | 360 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
361 | } |
362 | ||
0498b635 | 363 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 364 | { |
12941560 MH |
365 | if (p->ainsn.insn) { |
366 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
367 | p->ainsn.insn = NULL; | |
368 | } | |
1da177e4 LT |
369 | } |
370 | ||
3b60211c | 371 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 372 | { |
e7a510f9 AM |
373 | kcb->prev_kprobe.kp = kprobe_running(); |
374 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
375 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
376 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
377 | } |
378 | ||
3b60211c | 379 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 380 | { |
e7a510f9 AM |
381 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
382 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
8533bbe9 MH |
383 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
384 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
385 | } |
386 | ||
3b60211c | 387 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 388 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 389 | { |
e7a510f9 | 390 | __get_cpu_var(current_kprobe) = p; |
8533bbe9 | 391 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 392 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
aa3d7e3d | 393 | if (is_IF_modifier(p->ainsn.insn)) |
053de044 | 394 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
395 | } |
396 | ||
e7b5e11e | 397 | static void __kprobes clear_btf(void) |
1ecc798c RM |
398 | { |
399 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 400 | update_debugctlmsr(0); |
1ecc798c RM |
401 | } |
402 | ||
e7b5e11e | 403 | static void __kprobes restore_btf(void) |
1ecc798c RM |
404 | { |
405 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 406 | update_debugctlmsr(current->thread.debugctlmsr); |
1ecc798c RM |
407 | } |
408 | ||
4c4308cb | 409 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 410 | struct pt_regs *regs) |
73649dab | 411 | { |
8533bbe9 | 412 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 413 | |
4c4308cb | 414 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 415 | |
4c4308cb CH |
416 | /* Replace the return addr with trampoline addr */ |
417 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 418 | } |
f315decb | 419 | |
f315decb | 420 | static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
0f94eb63 | 421 | struct kprobe_ctlblk *kcb, int reenter) |
f315decb | 422 | { |
615d0ebb | 423 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
424 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
425 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
426 | if (!reenter) |
427 | reset_current_kprobe(); | |
428 | /* | |
429 | * Reentering boosted probe doesn't reset current_kprobe, | |
430 | * nor set current_kprobe, because it doesn't use single | |
431 | * stepping. | |
432 | */ | |
f315decb AS |
433 | regs->ip = (unsigned long)p->ainsn.insn; |
434 | preempt_enable_no_resched(); | |
435 | return; | |
436 | } | |
437 | #endif | |
0f94eb63 MH |
438 | if (reenter) { |
439 | save_previous_kprobe(kcb); | |
440 | set_current_kprobe(p, regs, kcb); | |
441 | kcb->kprobe_status = KPROBE_REENTER; | |
442 | } else | |
443 | kcb->kprobe_status = KPROBE_HIT_SS; | |
444 | /* Prepare real single stepping */ | |
445 | clear_btf(); | |
446 | regs->flags |= X86_EFLAGS_TF; | |
447 | regs->flags &= ~X86_EFLAGS_IF; | |
448 | /* single step inline if the instruction is an int3 */ | |
449 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
450 | regs->ip = (unsigned long)p->addr; | |
451 | else | |
452 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb AS |
453 | } |
454 | ||
40102d4a HH |
455 | /* |
456 | * We have reentered the kprobe_handler(), since another probe was hit while | |
457 | * within the handler. We save the original kprobes variables and just single | |
458 | * step on the instruction of the new probe without calling any user handlers. | |
459 | */ | |
59e87cdc MH |
460 | static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
461 | struct kprobe_ctlblk *kcb) | |
40102d4a | 462 | { |
f315decb AS |
463 | switch (kcb->kprobe_status) { |
464 | case KPROBE_HIT_SSDONE: | |
f315decb | 465 | case KPROBE_HIT_ACTIVE: |
fb8830e7 | 466 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 467 | setup_singlestep(p, regs, kcb, 1); |
f315decb AS |
468 | break; |
469 | case KPROBE_HIT_SS: | |
e9afe9e1 MH |
470 | /* A probe has been hit in the codepath leading up to, or just |
471 | * after, single-stepping of a probed instruction. This entire | |
472 | * codepath should strictly reside in .kprobes.text section. | |
473 | * Raise a BUG or we'll continue in an endless reentering loop | |
474 | * and eventually a stack overflow. | |
475 | */ | |
476 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
477 | p->addr); | |
478 | dump_kprobe(p); | |
479 | BUG(); | |
f315decb AS |
480 | default: |
481 | /* impossible cases */ | |
482 | WARN_ON(1); | |
fb8830e7 | 483 | return 0; |
59e87cdc | 484 | } |
f315decb | 485 | |
59e87cdc | 486 | return 1; |
40102d4a | 487 | } |
73649dab | 488 | |
8533bbe9 MH |
489 | /* |
490 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 491 | * remain disabled throughout this function. |
8533bbe9 MH |
492 | */ |
493 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 494 | { |
8533bbe9 | 495 | kprobe_opcode_t *addr; |
f315decb | 496 | struct kprobe *p; |
d217d545 AM |
497 | struct kprobe_ctlblk *kcb; |
498 | ||
8533bbe9 | 499 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
f315decb AS |
500 | if (*addr != BREAKPOINT_INSTRUCTION) { |
501 | /* | |
502 | * The breakpoint instruction was removed right | |
503 | * after we hit it. Another cpu has removed | |
504 | * either a probepoint or a debugger breakpoint | |
505 | * at this address. In either case, no further | |
506 | * handling of this interrupt is appropriate. | |
507 | * Back up over the (now missing) int3 and run | |
508 | * the original instruction. | |
509 | */ | |
510 | regs->ip = (unsigned long)addr; | |
511 | return 1; | |
512 | } | |
8533bbe9 | 513 | |
d217d545 AM |
514 | /* |
515 | * We don't want to be preempted for the entire | |
f315decb AS |
516 | * duration of kprobe processing. We conditionally |
517 | * re-enable preemption at the end of this function, | |
518 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
519 | */ |
520 | preempt_disable(); | |
1da177e4 | 521 | |
f315decb | 522 | kcb = get_kprobe_ctlblk(); |
b9760156 | 523 | p = get_kprobe(addr); |
f315decb | 524 | |
b9760156 | 525 | if (p) { |
b9760156 | 526 | if (kprobe_running()) { |
f315decb AS |
527 | if (reenter_kprobe(p, regs, kcb)) |
528 | return 1; | |
1da177e4 | 529 | } else { |
b9760156 HH |
530 | set_current_kprobe(p, regs, kcb); |
531 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 532 | |
1da177e4 | 533 | /* |
f315decb AS |
534 | * If we have no pre-handler or it returned 0, we |
535 | * continue with normal processing. If we have a | |
536 | * pre-handler and it returned non-zero, it prepped | |
537 | * for calling the break_handler below on re-entry | |
538 | * for jprobe processing, so get out doing nothing | |
539 | * more here. | |
1da177e4 | 540 | */ |
f315decb | 541 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 542 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 543 | return 1; |
b9760156 | 544 | } |
f315decb AS |
545 | } else if (kprobe_running()) { |
546 | p = __get_cpu_var(current_kprobe); | |
547 | if (p->break_handler && p->break_handler(p, regs)) { | |
0f94eb63 | 548 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 549 | return 1; |
1da177e4 | 550 | } |
f315decb | 551 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 552 | |
d217d545 | 553 | preempt_enable_no_resched(); |
f315decb | 554 | return 0; |
1da177e4 LT |
555 | } |
556 | ||
f007ea26 MH |
557 | #ifdef CONFIG_X86_64 |
558 | #define SAVE_REGS_STRING \ | |
559 | /* Skip cs, ip, orig_ax. */ \ | |
560 | " subq $24, %rsp\n" \ | |
561 | " pushq %rdi\n" \ | |
562 | " pushq %rsi\n" \ | |
563 | " pushq %rdx\n" \ | |
564 | " pushq %rcx\n" \ | |
565 | " pushq %rax\n" \ | |
566 | " pushq %r8\n" \ | |
567 | " pushq %r9\n" \ | |
568 | " pushq %r10\n" \ | |
569 | " pushq %r11\n" \ | |
570 | " pushq %rbx\n" \ | |
571 | " pushq %rbp\n" \ | |
572 | " pushq %r12\n" \ | |
573 | " pushq %r13\n" \ | |
574 | " pushq %r14\n" \ | |
575 | " pushq %r15\n" | |
576 | #define RESTORE_REGS_STRING \ | |
577 | " popq %r15\n" \ | |
578 | " popq %r14\n" \ | |
579 | " popq %r13\n" \ | |
580 | " popq %r12\n" \ | |
581 | " popq %rbp\n" \ | |
582 | " popq %rbx\n" \ | |
583 | " popq %r11\n" \ | |
584 | " popq %r10\n" \ | |
585 | " popq %r9\n" \ | |
586 | " popq %r8\n" \ | |
587 | " popq %rax\n" \ | |
588 | " popq %rcx\n" \ | |
589 | " popq %rdx\n" \ | |
590 | " popq %rsi\n" \ | |
591 | " popq %rdi\n" \ | |
592 | /* Skip orig_ax, ip, cs */ \ | |
593 | " addq $24, %rsp\n" | |
594 | #else | |
595 | #define SAVE_REGS_STRING \ | |
596 | /* Skip cs, ip, orig_ax and gs. */ \ | |
597 | " subl $16, %esp\n" \ | |
598 | " pushl %fs\n" \ | |
599 | " pushl %ds\n" \ | |
600 | " pushl %es\n" \ | |
601 | " pushl %eax\n" \ | |
602 | " pushl %ebp\n" \ | |
603 | " pushl %edi\n" \ | |
604 | " pushl %esi\n" \ | |
605 | " pushl %edx\n" \ | |
606 | " pushl %ecx\n" \ | |
607 | " pushl %ebx\n" | |
608 | #define RESTORE_REGS_STRING \ | |
609 | " popl %ebx\n" \ | |
610 | " popl %ecx\n" \ | |
611 | " popl %edx\n" \ | |
612 | " popl %esi\n" \ | |
613 | " popl %edi\n" \ | |
614 | " popl %ebp\n" \ | |
615 | " popl %eax\n" \ | |
616 | /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\ | |
617 | " addl $24, %esp\n" | |
618 | #endif | |
619 | ||
73649dab | 620 | /* |
da07ab03 MH |
621 | * When a retprobed function returns, this code saves registers and |
622 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 623 | */ |
f1452d42 | 624 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 625 | { |
d6be29b8 MH |
626 | asm volatile ( |
627 | ".global kretprobe_trampoline\n" | |
da07ab03 | 628 | "kretprobe_trampoline: \n" |
d6be29b8 | 629 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
630 | /* We don't bother saving the ss register */ |
631 | " pushq %rsp\n" | |
632 | " pushfq\n" | |
f007ea26 | 633 | SAVE_REGS_STRING |
da07ab03 MH |
634 | " movq %rsp, %rdi\n" |
635 | " call trampoline_handler\n" | |
636 | /* Replace saved sp with true return address. */ | |
637 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 638 | RESTORE_REGS_STRING |
da07ab03 | 639 | " popfq\n" |
d6be29b8 MH |
640 | #else |
641 | " pushf\n" | |
f007ea26 | 642 | SAVE_REGS_STRING |
d6be29b8 MH |
643 | " movl %esp, %eax\n" |
644 | " call trampoline_handler\n" | |
645 | /* Move flags to cs */ | |
fee039a1 MH |
646 | " movl 56(%esp), %edx\n" |
647 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 648 | /* Replace saved flags with true return address. */ |
fee039a1 | 649 | " movl %eax, 56(%esp)\n" |
f007ea26 | 650 | RESTORE_REGS_STRING |
d6be29b8 MH |
651 | " popf\n" |
652 | #endif | |
da07ab03 | 653 | " ret\n"); |
1017579a | 654 | } |
73649dab RL |
655 | |
656 | /* | |
da07ab03 | 657 | * Called from kretprobe_trampoline |
73649dab | 658 | */ |
f1452d42 | 659 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 660 | { |
62c27be0 | 661 | struct kretprobe_instance *ri = NULL; |
99219a3f | 662 | struct hlist_head *head, empty_rp; |
62c27be0 | 663 | struct hlist_node *node, *tmp; |
991a51d8 | 664 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 665 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
73649dab | 666 | |
99219a3f | 667 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 668 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 669 | /* fixup registers */ |
d6be29b8 | 670 | #ifdef CONFIG_X86_64 |
da07ab03 | 671 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
672 | #else |
673 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 674 | regs->gs = 0; |
d6be29b8 | 675 | #endif |
da07ab03 | 676 | regs->ip = trampoline_address; |
8533bbe9 | 677 | regs->orig_ax = ~0UL; |
73649dab | 678 | |
ba8af12f RL |
679 | /* |
680 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 681 | * task either because multiple functions in the call path have |
025dfdaf | 682 | * return probes installed on them, and/or more than one |
ba8af12f RL |
683 | * return probe was registered for a target function. |
684 | * | |
685 | * We can handle this because: | |
8533bbe9 | 686 | * - instances are always pushed into the head of the list |
ba8af12f | 687 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
688 | * function, the (chronologically) first instance's ret_addr |
689 | * will be the real return address, and all the rest will | |
690 | * point to kretprobe_trampoline. | |
ba8af12f RL |
691 | */ |
692 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 693 | if (ri->task != current) |
ba8af12f | 694 | /* another task is sharing our hash bucket */ |
62c27be0 | 695 | continue; |
ba8af12f | 696 | |
da07ab03 MH |
697 | if (ri->rp && ri->rp->handler) { |
698 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
699 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 700 | ri->rp->handler(ri, regs); |
da07ab03 MH |
701 | __get_cpu_var(current_kprobe) = NULL; |
702 | } | |
ba8af12f RL |
703 | |
704 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 705 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
706 | |
707 | if (orig_ret_address != trampoline_address) | |
708 | /* | |
709 | * This is the real return address. Any other | |
710 | * instances associated with this task are for | |
711 | * other calls deeper on the call stack | |
712 | */ | |
713 | break; | |
73649dab | 714 | } |
ba8af12f | 715 | |
0f95b7fc | 716 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 717 | |
ef53d9c5 | 718 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 719 | |
99219a3f | 720 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
721 | hlist_del(&ri->hlist); | |
722 | kfree(ri); | |
723 | } | |
da07ab03 | 724 | return (void *)orig_ret_address; |
73649dab RL |
725 | } |
726 | ||
1da177e4 LT |
727 | /* |
728 | * Called after single-stepping. p->addr is the address of the | |
729 | * instruction whose first byte has been replaced by the "int 3" | |
730 | * instruction. To avoid the SMP problems that can occur when we | |
731 | * temporarily put back the original opcode to single-step, we | |
732 | * single-stepped a copy of the instruction. The address of this | |
733 | * copy is p->ainsn.insn. | |
734 | * | |
735 | * This function prepares to return from the post-single-step | |
736 | * interrupt. We have to fix up the stack as follows: | |
737 | * | |
738 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 739 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
740 | * it relative to the original instruction. |
741 | * | |
742 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 743 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
744 | * |
745 | * 2) If the single-stepped instruction was a call, the return address | |
746 | * that is atop the stack is the address following the copied instruction. | |
747 | * We need to make it the address following the original instruction. | |
aa470140 MH |
748 | * |
749 | * If this is the first time we've single-stepped the instruction at | |
750 | * this probepoint, and the instruction is boostable, boost it: add a | |
751 | * jump instruction after the copied instruction, that jumps to the next | |
752 | * instruction after the probepoint. | |
1da177e4 | 753 | */ |
e7a510f9 AM |
754 | static void __kprobes resume_execution(struct kprobe *p, |
755 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 756 | { |
8533bbe9 MH |
757 | unsigned long *tos = stack_addr(regs); |
758 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
759 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
760 | kprobe_opcode_t *insn = p->ainsn.insn; |
761 | ||
762 | /*skip the REX prefix*/ | |
9930927f | 763 | if (is_REX_prefix(insn)) |
1da177e4 LT |
764 | insn++; |
765 | ||
053de044 | 766 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 767 | switch (*insn) { |
0b0122fa | 768 | case 0x9c: /* pushfl */ |
053de044 | 769 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 770 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 771 | break; |
0b0122fa MH |
772 | case 0xc2: /* iret/ret/lret */ |
773 | case 0xc3: | |
0b9e2cac | 774 | case 0xca: |
0b0122fa MH |
775 | case 0xcb: |
776 | case 0xcf: | |
777 | case 0xea: /* jmp absolute -- ip is correct */ | |
778 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 779 | p->ainsn.boostable = 1; |
0b0122fa MH |
780 | goto no_change; |
781 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 782 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 783 | break; |
e7b5e11e | 784 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
785 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
786 | *tos = orig_ip + (*tos - copy_ip); | |
787 | goto no_change; | |
788 | #endif | |
1da177e4 | 789 | case 0xff: |
dc49e344 | 790 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
791 | /* |
792 | * call absolute, indirect | |
793 | * Fix return addr; ip is correct. | |
794 | * But this is not boostable | |
795 | */ | |
796 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 797 | goto no_change; |
8533bbe9 MH |
798 | } else if (((insn[1] & 0x31) == 0x20) || |
799 | ((insn[1] & 0x31) == 0x21)) { | |
800 | /* | |
801 | * jmp near and far, absolute indirect | |
802 | * ip is correct. And this is boostable | |
803 | */ | |
aa470140 | 804 | p->ainsn.boostable = 1; |
0b0122fa | 805 | goto no_change; |
1da177e4 | 806 | } |
1da177e4 LT |
807 | default: |
808 | break; | |
809 | } | |
810 | ||
aa470140 | 811 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
812 | if ((regs->ip > copy_ip) && |
813 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
814 | /* |
815 | * These instructions can be executed directly if it | |
816 | * jumps back to correct address. | |
817 | */ | |
818 | set_jmp_op((void *)regs->ip, | |
8533bbe9 | 819 | (void *)orig_ip + (regs->ip - copy_ip)); |
aa470140 MH |
820 | p->ainsn.boostable = 1; |
821 | } else { | |
822 | p->ainsn.boostable = -1; | |
823 | } | |
824 | } | |
825 | ||
8533bbe9 | 826 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 827 | |
0b0122fa | 828 | no_change: |
1ecc798c | 829 | restore_btf(); |
1da177e4 LT |
830 | } |
831 | ||
8533bbe9 MH |
832 | /* |
833 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 834 | * remain disabled throughout this function. |
8533bbe9 MH |
835 | */ |
836 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 837 | { |
e7a510f9 AM |
838 | struct kprobe *cur = kprobe_running(); |
839 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
840 | ||
841 | if (!cur) | |
1da177e4 LT |
842 | return 0; |
843 | ||
acb5b8a2 YL |
844 | resume_execution(cur, regs, kcb); |
845 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 846 | |
e7a510f9 AM |
847 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
848 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
849 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 850 | } |
1da177e4 | 851 | |
8533bbe9 | 852 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
853 | if (kcb->kprobe_status == KPROBE_REENTER) { |
854 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 855 | goto out; |
aa3d7e3d | 856 | } |
e7a510f9 | 857 | reset_current_kprobe(); |
aa3d7e3d | 858 | out: |
1da177e4 LT |
859 | preempt_enable_no_resched(); |
860 | ||
861 | /* | |
65ea5b03 | 862 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
863 | * will have TF set, in which case, continue the remaining processing |
864 | * of do_debug, as if this is not a probe hit. | |
865 | */ | |
053de044 | 866 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
867 | return 0; |
868 | ||
869 | return 1; | |
870 | } | |
871 | ||
0f2fbdcb | 872 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 873 | { |
e7a510f9 AM |
874 | struct kprobe *cur = kprobe_running(); |
875 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
876 | ||
d6be29b8 | 877 | switch (kcb->kprobe_status) { |
c28f8966 PP |
878 | case KPROBE_HIT_SS: |
879 | case KPROBE_REENTER: | |
880 | /* | |
881 | * We are here because the instruction being single | |
882 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 883 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
884 | * and allow the page fault handler to continue as a |
885 | * normal page fault. | |
886 | */ | |
65ea5b03 | 887 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 888 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
889 | if (kcb->kprobe_status == KPROBE_REENTER) |
890 | restore_previous_kprobe(kcb); | |
891 | else | |
892 | reset_current_kprobe(); | |
1da177e4 | 893 | preempt_enable_no_resched(); |
c28f8966 PP |
894 | break; |
895 | case KPROBE_HIT_ACTIVE: | |
896 | case KPROBE_HIT_SSDONE: | |
897 | /* | |
898 | * We increment the nmissed count for accounting, | |
8533bbe9 | 899 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
900 | * these specific fault cases. |
901 | */ | |
902 | kprobes_inc_nmissed_count(cur); | |
903 | ||
904 | /* | |
905 | * We come here because instructions in the pre/post | |
906 | * handler caused the page_fault, this could happen | |
907 | * if handler tries to access user space by | |
908 | * copy_from_user(), get_user() etc. Let the | |
909 | * user-specified handler try to fix it first. | |
910 | */ | |
911 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
912 | return 1; | |
913 | ||
914 | /* | |
915 | * In case the user-specified fault handler returned | |
916 | * zero, try to fix up. | |
917 | */ | |
d6be29b8 MH |
918 | if (fixup_exception(regs)) |
919 | return 1; | |
6d48583b | 920 | |
c28f8966 | 921 | /* |
8533bbe9 | 922 | * fixup routine could not handle it, |
c28f8966 PP |
923 | * Let do_page_fault() fix it. |
924 | */ | |
925 | break; | |
926 | default: | |
927 | break; | |
1da177e4 LT |
928 | } |
929 | return 0; | |
930 | } | |
931 | ||
932 | /* | |
933 | * Wrapper routine for handling exceptions. | |
934 | */ | |
0f2fbdcb PP |
935 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
936 | unsigned long val, void *data) | |
1da177e4 | 937 | { |
ade1af77 | 938 | struct die_args *args = data; |
66ff2d06 AM |
939 | int ret = NOTIFY_DONE; |
940 | ||
8533bbe9 | 941 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 942 | return ret; |
943 | ||
1da177e4 LT |
944 | switch (val) { |
945 | case DIE_INT3: | |
946 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 947 | ret = NOTIFY_STOP; |
1da177e4 LT |
948 | break; |
949 | case DIE_DEBUG: | |
62edab90 P |
950 | if (post_kprobe_handler(args->regs)) { |
951 | /* | |
952 | * Reset the BS bit in dr6 (pointed by args->err) to | |
953 | * denote completion of processing | |
954 | */ | |
955 | (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; | |
66ff2d06 | 956 | ret = NOTIFY_STOP; |
62edab90 | 957 | } |
1da177e4 LT |
958 | break; |
959 | case DIE_GPF: | |
b506a9d0 QB |
960 | /* |
961 | * To be potentially processing a kprobe fault and to | |
962 | * trust the result from kprobe_running(), we have | |
963 | * be non-preemptible. | |
964 | */ | |
965 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 966 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 967 | ret = NOTIFY_STOP; |
1da177e4 LT |
968 | break; |
969 | default: | |
970 | break; | |
971 | } | |
66ff2d06 | 972 | return ret; |
1da177e4 LT |
973 | } |
974 | ||
0f2fbdcb | 975 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
976 | { |
977 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
978 | unsigned long addr; | |
e7a510f9 | 979 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 980 | |
e7a510f9 | 981 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
982 | kcb->jprobe_saved_sp = stack_addr(regs); |
983 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
984 | ||
1da177e4 LT |
985 | /* |
986 | * As Linus pointed out, gcc assumes that the callee | |
987 | * owns the argument space and could overwrite it, e.g. | |
988 | * tailcall optimization. So, to be absolutely safe | |
989 | * we also save and restore enough stack bytes to cover | |
990 | * the argument area. | |
991 | */ | |
e7a510f9 | 992 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 993 | MIN_STACK_SIZE(addr)); |
053de044 | 994 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 995 | trace_hardirqs_off(); |
65ea5b03 | 996 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
997 | return 1; |
998 | } | |
999 | ||
0f2fbdcb | 1000 | void __kprobes jprobe_return(void) |
1da177e4 | 1001 | { |
e7a510f9 AM |
1002 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1003 | ||
d6be29b8 MH |
1004 | asm volatile ( |
1005 | #ifdef CONFIG_X86_64 | |
1006 | " xchg %%rbx,%%rsp \n" | |
1007 | #else | |
1008 | " xchgl %%ebx,%%esp \n" | |
1009 | #endif | |
1010 | " int3 \n" | |
1011 | " .globl jprobe_return_end\n" | |
1012 | " jprobe_return_end: \n" | |
1013 | " nop \n"::"b" | |
1014 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1015 | } |
1016 | ||
0f2fbdcb | 1017 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1018 | { |
e7a510f9 | 1019 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1020 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1021 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1022 | ||
d6be29b8 MH |
1023 | if ((addr > (u8 *) jprobe_return) && |
1024 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1025 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1026 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1027 | printk(KERN_ERR |
1028 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1029 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1030 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1031 | show_registers(saved_regs); |
d6be29b8 | 1032 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1033 | show_registers(regs); |
1034 | BUG(); | |
1035 | } | |
e7a510f9 | 1036 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1037 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1038 | kcb->jprobes_stack, | |
1039 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1040 | preempt_enable_no_resched(); |
1da177e4 LT |
1041 | return 1; |
1042 | } | |
1043 | return 0; | |
1044 | } | |
ba8af12f | 1045 | |
6772926b | 1046 | int __init arch_init_kprobes(void) |
ba8af12f | 1047 | { |
da07ab03 | 1048 | return 0; |
ba8af12f | 1049 | } |
bf8f6e5b AM |
1050 | |
1051 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1052 | { | |
bf8f6e5b AM |
1053 | return 0; |
1054 | } |