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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> |
c0f7ac3a | 52 | #include <linux/ftrace.h> |
9ec4b1f3 | 53 | |
8533bbe9 MH |
54 | #include <asm/cacheflush.h> |
55 | #include <asm/desc.h> | |
1da177e4 | 56 | #include <asm/pgtable.h> |
c28f8966 | 57 | #include <asm/uaccess.h> |
19d36ccd | 58 | #include <asm/alternative.h> |
b46b3d70 | 59 | #include <asm/insn.h> |
62edab90 | 60 | #include <asm/debugreg.h> |
1da177e4 | 61 | |
1da177e4 LT |
62 | void jprobe_return_end(void); |
63 | ||
e7a510f9 AM |
64 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
65 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 66 | |
98272ed0 | 67 | #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) |
8533bbe9 MH |
68 | |
69 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
70 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
71 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
72 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
73 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
74 | << (row % 32)) | |
75 | /* | |
76 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
77 | * Groups, and some special opcodes can not boost. | |
78 | */ | |
79 | static const u32 twobyte_is_boostable[256 / 32] = { | |
80 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
81 | /* ---------------------------------------------- */ | |
82 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
83 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ | |
84 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ | |
85 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
86 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
87 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
88 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
89 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
90 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
91 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
92 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
93 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
94 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
95 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
96 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
97 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
98 | /* ----------------------------------------------- */ | |
99 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
100 | }; | |
8533bbe9 MH |
101 | #undef W |
102 | ||
f438d914 MH |
103 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
104 | {"__switch_to", }, /* This function switches only current task, but | |
105 | doesn't switch kernel stack.*/ | |
106 | {NULL, NULL} /* Terminator */ | |
107 | }; | |
108 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
109 | ||
c0f7ac3a | 110 | static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) |
aa470140 | 111 | { |
c0f7ac3a MH |
112 | struct __arch_relative_insn { |
113 | u8 op; | |
aa470140 | 114 | s32 raddr; |
c0f7ac3a MH |
115 | } __attribute__((packed)) *insn; |
116 | ||
117 | insn = (struct __arch_relative_insn *)from; | |
118 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
119 | insn->op = op; | |
120 | } | |
121 | ||
122 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
123 | static void __kprobes synthesize_reljump(void *from, void *to) | |
124 | { | |
125 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 MH |
126 | } |
127 | ||
9930927f HH |
128 | /* |
129 | * Check for the REX prefix which can only exist on X86_64 | |
130 | * X86_32 always returns 0 | |
131 | */ | |
132 | static int __kprobes is_REX_prefix(kprobe_opcode_t *insn) | |
133 | { | |
134 | #ifdef CONFIG_X86_64 | |
135 | if ((*insn & 0xf0) == 0x40) | |
136 | return 1; | |
137 | #endif | |
138 | return 0; | |
139 | } | |
140 | ||
aa470140 | 141 | /* |
d6be29b8 MH |
142 | * Returns non-zero if opcode is boostable. |
143 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 144 | */ |
e7b5e11e | 145 | static int __kprobes can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 146 | { |
aa470140 MH |
147 | kprobe_opcode_t opcode; |
148 | kprobe_opcode_t *orig_opcodes = opcodes; | |
149 | ||
cde5edbd | 150 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
151 | return 0; /* Page fault may occur on this address. */ |
152 | ||
aa470140 MH |
153 | retry: |
154 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
155 | return 0; | |
156 | opcode = *(opcodes++); | |
157 | ||
158 | /* 2nd-byte opcode */ | |
159 | if (opcode == 0x0f) { | |
160 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
161 | return 0; | |
8533bbe9 MH |
162 | return test_bit(*opcodes, |
163 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
164 | } |
165 | ||
166 | switch (opcode & 0xf0) { | |
d6be29b8 | 167 | #ifdef CONFIG_X86_64 |
aa470140 MH |
168 | case 0x40: |
169 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 170 | #endif |
aa470140 MH |
171 | case 0x60: |
172 | if (0x63 < opcode && opcode < 0x67) | |
173 | goto retry; /* prefixes */ | |
174 | /* can't boost Address-size override and bound */ | |
175 | return (opcode != 0x62 && opcode != 0x67); | |
176 | case 0x70: | |
177 | return 0; /* can't boost conditional jump */ | |
178 | case 0xc0: | |
179 | /* can't boost software-interruptions */ | |
180 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
181 | case 0xd0: | |
182 | /* can boost AA* and XLAT */ | |
183 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
184 | case 0xe0: | |
185 | /* can boost in/out and absolute jmps */ | |
186 | return ((opcode & 0x04) || opcode == 0xea); | |
187 | case 0xf0: | |
188 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
189 | goto retry; /* lock/rep(ne) prefix */ | |
190 | /* clear and set flags are boostable */ | |
191 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
192 | default: | |
193 | /* segment override prefixes are boostable */ | |
194 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
195 | goto retry; /* prefixes */ | |
196 | /* CS override prefix and call are not boostable */ | |
197 | return (opcode != 0x2e && opcode != 0x9a); | |
198 | } | |
199 | } | |
200 | ||
b46b3d70 MH |
201 | /* Recover the probed instruction at addr for further analysis. */ |
202 | static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) | |
203 | { | |
204 | struct kprobe *kp; | |
205 | kp = get_kprobe((void *)addr); | |
206 | if (!kp) | |
207 | return -EINVAL; | |
208 | ||
209 | /* | |
210 | * Basically, kp->ainsn.insn has an original instruction. | |
211 | * However, RIP-relative instruction can not do single-stepping | |
c0f7ac3a | 212 | * at different place, __copy_instruction() tweaks the displacement of |
b46b3d70 MH |
213 | * that instruction. In that case, we can't recover the instruction |
214 | * from the kp->ainsn.insn. | |
215 | * | |
216 | * On the other hand, kp->opcode has a copy of the first byte of | |
217 | * the probed instruction, which is overwritten by int3. And | |
218 | * the instruction at kp->addr is not modified by kprobes except | |
219 | * for the first byte, we can recover the original instruction | |
220 | * from it and kp->opcode. | |
221 | */ | |
222 | memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
223 | buf[0] = kp->opcode; | |
224 | return 0; | |
225 | } | |
226 | ||
227 | /* Dummy buffers for kallsyms_lookup */ | |
228 | static char __dummy_buf[KSYM_NAME_LEN]; | |
229 | ||
230 | /* Check if paddr is at an instruction boundary */ | |
231 | static int __kprobes can_probe(unsigned long paddr) | |
232 | { | |
233 | int ret; | |
234 | unsigned long addr, offset = 0; | |
235 | struct insn insn; | |
236 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
237 | ||
238 | if (!kallsyms_lookup(paddr, NULL, &offset, NULL, __dummy_buf)) | |
239 | return 0; | |
240 | ||
241 | /* Decode instructions */ | |
242 | addr = paddr - offset; | |
243 | while (addr < paddr) { | |
244 | kernel_insn_init(&insn, (void *)addr); | |
245 | insn_get_opcode(&insn); | |
246 | ||
247 | /* | |
248 | * Check if the instruction has been modified by another | |
249 | * kprobe, in which case we replace the breakpoint by the | |
250 | * original instruction in our buffer. | |
251 | */ | |
252 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
253 | ret = recover_probed_instruction(buf, addr); | |
254 | if (ret) | |
255 | /* | |
256 | * Another debugging subsystem might insert | |
257 | * this breakpoint. In that case, we can't | |
258 | * recover it. | |
259 | */ | |
260 | return 0; | |
261 | kernel_insn_init(&insn, buf); | |
262 | } | |
263 | insn_get_length(&insn); | |
264 | addr += insn.length; | |
265 | } | |
266 | ||
267 | return (addr == paddr); | |
268 | } | |
269 | ||
1da177e4 | 270 | /* |
d6be29b8 | 271 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 272 | */ |
8645419c | 273 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
274 | { |
275 | switch (*insn) { | |
276 | case 0xfa: /* cli */ | |
277 | case 0xfb: /* sti */ | |
278 | case 0xcf: /* iret/iretd */ | |
279 | case 0x9d: /* popf/popfd */ | |
280 | return 1; | |
281 | } | |
9930927f | 282 | |
8533bbe9 | 283 | /* |
9930927f | 284 | * on X86_64, 0x40-0x4f are REX prefixes so we need to look |
8533bbe9 MH |
285 | * at the next byte instead.. but of course not recurse infinitely |
286 | */ | |
9930927f | 287 | if (is_REX_prefix(insn)) |
8533bbe9 | 288 | return is_IF_modifier(++insn); |
9930927f | 289 | |
1da177e4 LT |
290 | return 0; |
291 | } | |
292 | ||
293 | /* | |
c0f7ac3a MH |
294 | * Copy an instruction and adjust the displacement if the instruction |
295 | * uses the %rip-relative addressing mode. | |
aa470140 | 296 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 297 | * If not, return null. |
31f80e45 | 298 | * Only applicable to 64-bit x86. |
1da177e4 | 299 | */ |
c0f7ac3a | 300 | static int __kprobes __copy_instruction(u8 *dest, u8 *src, int recover) |
1da177e4 | 301 | { |
89ae465b | 302 | struct insn insn; |
c0f7ac3a MH |
303 | int ret; |
304 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
1da177e4 | 305 | |
c0f7ac3a MH |
306 | kernel_insn_init(&insn, src); |
307 | if (recover) { | |
308 | insn_get_opcode(&insn); | |
309 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
310 | ret = recover_probed_instruction(buf, | |
311 | (unsigned long)src); | |
312 | if (ret) | |
313 | return 0; | |
314 | kernel_insn_init(&insn, buf); | |
315 | } | |
316 | } | |
317 | insn_get_length(&insn); | |
318 | memcpy(dest, insn.kaddr, insn.length); | |
319 | ||
320 | #ifdef CONFIG_X86_64 | |
89ae465b MH |
321 | if (insn_rip_relative(&insn)) { |
322 | s64 newdisp; | |
323 | u8 *disp; | |
c0f7ac3a | 324 | kernel_insn_init(&insn, dest); |
89ae465b MH |
325 | insn_get_displacement(&insn); |
326 | /* | |
327 | * The copied instruction uses the %rip-relative addressing | |
328 | * mode. Adjust the displacement for the difference between | |
329 | * the original location of this instruction and the location | |
330 | * of the copy that will actually be run. The tricky bit here | |
331 | * is making sure that the sign extension happens correctly in | |
332 | * this calculation, since we need a signed 32-bit result to | |
333 | * be sign-extended to 64 bits when it's added to the %rip | |
334 | * value and yield the same 64-bit result that the sign- | |
335 | * extension of the original signed 32-bit displacement would | |
336 | * have given. | |
337 | */ | |
c0f7ac3a MH |
338 | newdisp = (u8 *) src + (s64) insn.displacement.value - |
339 | (u8 *) dest; | |
89ae465b | 340 | BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */ |
c0f7ac3a | 341 | disp = (u8 *) dest + insn_offset_displacement(&insn); |
89ae465b | 342 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 343 | } |
d6be29b8 | 344 | #endif |
c0f7ac3a | 345 | return insn.length; |
31f80e45 | 346 | } |
1da177e4 | 347 | |
f709b122 | 348 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 349 | { |
c0f7ac3a MH |
350 | /* |
351 | * Copy an instruction without recovering int3, because it will be | |
352 | * put by another subsystem. | |
353 | */ | |
354 | __copy_instruction(p->ainsn.insn, p->addr, 0); | |
31f80e45 | 355 | |
8533bbe9 | 356 | if (can_boost(p->addr)) |
aa470140 | 357 | p->ainsn.boostable = 0; |
8533bbe9 | 358 | else |
aa470140 | 359 | p->ainsn.boostable = -1; |
8533bbe9 | 360 | |
7e1048b1 | 361 | p->opcode = *p->addr; |
1da177e4 LT |
362 | } |
363 | ||
8533bbe9 MH |
364 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
365 | { | |
4554dbcb MH |
366 | if (alternatives_text_reserved(p->addr, p->addr)) |
367 | return -EINVAL; | |
368 | ||
b46b3d70 MH |
369 | if (!can_probe((unsigned long)p->addr)) |
370 | return -EILSEQ; | |
8533bbe9 MH |
371 | /* insn: must be on special executable page on x86. */ |
372 | p->ainsn.insn = get_insn_slot(); | |
373 | if (!p->ainsn.insn) | |
374 | return -ENOMEM; | |
375 | arch_copy_kprobe(p); | |
376 | return 0; | |
377 | } | |
378 | ||
0f2fbdcb | 379 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 380 | { |
19d36ccd | 381 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
382 | } |
383 | ||
0f2fbdcb | 384 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 385 | { |
19d36ccd | 386 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
387 | } |
388 | ||
0498b635 | 389 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 390 | { |
12941560 MH |
391 | if (p->ainsn.insn) { |
392 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
393 | p->ainsn.insn = NULL; | |
394 | } | |
1da177e4 LT |
395 | } |
396 | ||
3b60211c | 397 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 398 | { |
e7a510f9 AM |
399 | kcb->prev_kprobe.kp = kprobe_running(); |
400 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
401 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
402 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
403 | } |
404 | ||
3b60211c | 405 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 406 | { |
e7a510f9 AM |
407 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
408 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
8533bbe9 MH |
409 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
410 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
411 | } |
412 | ||
3b60211c | 413 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 414 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 415 | { |
e7a510f9 | 416 | __get_cpu_var(current_kprobe) = p; |
8533bbe9 | 417 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 418 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
aa3d7e3d | 419 | if (is_IF_modifier(p->ainsn.insn)) |
053de044 | 420 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
421 | } |
422 | ||
e7b5e11e | 423 | static void __kprobes clear_btf(void) |
1ecc798c | 424 | { |
ea8e61b7 PZ |
425 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
426 | unsigned long debugctl = get_debugctlmsr(); | |
427 | ||
428 | debugctl &= ~DEBUGCTLMSR_BTF; | |
429 | update_debugctlmsr(debugctl); | |
430 | } | |
1ecc798c RM |
431 | } |
432 | ||
e7b5e11e | 433 | static void __kprobes restore_btf(void) |
1ecc798c | 434 | { |
ea8e61b7 PZ |
435 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
436 | unsigned long debugctl = get_debugctlmsr(); | |
437 | ||
438 | debugctl |= DEBUGCTLMSR_BTF; | |
439 | update_debugctlmsr(debugctl); | |
440 | } | |
1ecc798c RM |
441 | } |
442 | ||
4c4308cb | 443 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 444 | struct pt_regs *regs) |
73649dab | 445 | { |
8533bbe9 | 446 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 447 | |
4c4308cb | 448 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 449 | |
4c4308cb CH |
450 | /* Replace the return addr with trampoline addr */ |
451 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 452 | } |
f315decb | 453 | |
c0f7ac3a MH |
454 | #ifdef CONFIG_OPTPROBES |
455 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
456 | struct pt_regs *regs, | |
457 | int reenter); | |
458 | #else | |
459 | #define setup_detour_execution(p, regs, reenter) (0) | |
460 | #endif | |
461 | ||
f315decb | 462 | static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
0f94eb63 | 463 | struct kprobe_ctlblk *kcb, int reenter) |
f315decb | 464 | { |
c0f7ac3a MH |
465 | if (setup_detour_execution(p, regs, reenter)) |
466 | return; | |
467 | ||
615d0ebb | 468 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
469 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
470 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
471 | if (!reenter) |
472 | reset_current_kprobe(); | |
473 | /* | |
474 | * Reentering boosted probe doesn't reset current_kprobe, | |
475 | * nor set current_kprobe, because it doesn't use single | |
476 | * stepping. | |
477 | */ | |
f315decb AS |
478 | regs->ip = (unsigned long)p->ainsn.insn; |
479 | preempt_enable_no_resched(); | |
480 | return; | |
481 | } | |
482 | #endif | |
0f94eb63 MH |
483 | if (reenter) { |
484 | save_previous_kprobe(kcb); | |
485 | set_current_kprobe(p, regs, kcb); | |
486 | kcb->kprobe_status = KPROBE_REENTER; | |
487 | } else | |
488 | kcb->kprobe_status = KPROBE_HIT_SS; | |
489 | /* Prepare real single stepping */ | |
490 | clear_btf(); | |
491 | regs->flags |= X86_EFLAGS_TF; | |
492 | regs->flags &= ~X86_EFLAGS_IF; | |
493 | /* single step inline if the instruction is an int3 */ | |
494 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
495 | regs->ip = (unsigned long)p->addr; | |
496 | else | |
497 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb AS |
498 | } |
499 | ||
40102d4a HH |
500 | /* |
501 | * We have reentered the kprobe_handler(), since another probe was hit while | |
502 | * within the handler. We save the original kprobes variables and just single | |
503 | * step on the instruction of the new probe without calling any user handlers. | |
504 | */ | |
59e87cdc MH |
505 | static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
506 | struct kprobe_ctlblk *kcb) | |
40102d4a | 507 | { |
f315decb AS |
508 | switch (kcb->kprobe_status) { |
509 | case KPROBE_HIT_SSDONE: | |
f315decb | 510 | case KPROBE_HIT_ACTIVE: |
fb8830e7 | 511 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 512 | setup_singlestep(p, regs, kcb, 1); |
f315decb AS |
513 | break; |
514 | case KPROBE_HIT_SS: | |
e9afe9e1 MH |
515 | /* A probe has been hit in the codepath leading up to, or just |
516 | * after, single-stepping of a probed instruction. This entire | |
517 | * codepath should strictly reside in .kprobes.text section. | |
518 | * Raise a BUG or we'll continue in an endless reentering loop | |
519 | * and eventually a stack overflow. | |
520 | */ | |
521 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
522 | p->addr); | |
523 | dump_kprobe(p); | |
524 | BUG(); | |
f315decb AS |
525 | default: |
526 | /* impossible cases */ | |
527 | WARN_ON(1); | |
fb8830e7 | 528 | return 0; |
59e87cdc | 529 | } |
f315decb | 530 | |
59e87cdc | 531 | return 1; |
40102d4a | 532 | } |
73649dab | 533 | |
8533bbe9 MH |
534 | /* |
535 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 536 | * remain disabled throughout this function. |
8533bbe9 MH |
537 | */ |
538 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 539 | { |
8533bbe9 | 540 | kprobe_opcode_t *addr; |
f315decb | 541 | struct kprobe *p; |
d217d545 AM |
542 | struct kprobe_ctlblk *kcb; |
543 | ||
8533bbe9 | 544 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
545 | /* |
546 | * We don't want to be preempted for the entire | |
f315decb AS |
547 | * duration of kprobe processing. We conditionally |
548 | * re-enable preemption at the end of this function, | |
549 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
550 | */ |
551 | preempt_disable(); | |
1da177e4 | 552 | |
f315decb | 553 | kcb = get_kprobe_ctlblk(); |
b9760156 | 554 | p = get_kprobe(addr); |
f315decb | 555 | |
b9760156 | 556 | if (p) { |
b9760156 | 557 | if (kprobe_running()) { |
f315decb AS |
558 | if (reenter_kprobe(p, regs, kcb)) |
559 | return 1; | |
1da177e4 | 560 | } else { |
b9760156 HH |
561 | set_current_kprobe(p, regs, kcb); |
562 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 563 | |
1da177e4 | 564 | /* |
f315decb AS |
565 | * If we have no pre-handler or it returned 0, we |
566 | * continue with normal processing. If we have a | |
567 | * pre-handler and it returned non-zero, it prepped | |
568 | * for calling the break_handler below on re-entry | |
569 | * for jprobe processing, so get out doing nothing | |
570 | * more here. | |
1da177e4 | 571 | */ |
f315decb | 572 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 573 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 574 | return 1; |
b9760156 | 575 | } |
829e9245 MH |
576 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
577 | /* | |
578 | * The breakpoint instruction was removed right | |
579 | * after we hit it. Another cpu has removed | |
580 | * either a probepoint or a debugger breakpoint | |
581 | * at this address. In either case, no further | |
582 | * handling of this interrupt is appropriate. | |
583 | * Back up over the (now missing) int3 and run | |
584 | * the original instruction. | |
585 | */ | |
586 | regs->ip = (unsigned long)addr; | |
587 | preempt_enable_no_resched(); | |
588 | return 1; | |
f315decb AS |
589 | } else if (kprobe_running()) { |
590 | p = __get_cpu_var(current_kprobe); | |
591 | if (p->break_handler && p->break_handler(p, regs)) { | |
0f94eb63 | 592 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 593 | return 1; |
1da177e4 | 594 | } |
f315decb | 595 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 596 | |
d217d545 | 597 | preempt_enable_no_resched(); |
f315decb | 598 | return 0; |
1da177e4 LT |
599 | } |
600 | ||
f007ea26 MH |
601 | #ifdef CONFIG_X86_64 |
602 | #define SAVE_REGS_STRING \ | |
603 | /* Skip cs, ip, orig_ax. */ \ | |
604 | " subq $24, %rsp\n" \ | |
605 | " pushq %rdi\n" \ | |
606 | " pushq %rsi\n" \ | |
607 | " pushq %rdx\n" \ | |
608 | " pushq %rcx\n" \ | |
609 | " pushq %rax\n" \ | |
610 | " pushq %r8\n" \ | |
611 | " pushq %r9\n" \ | |
612 | " pushq %r10\n" \ | |
613 | " pushq %r11\n" \ | |
614 | " pushq %rbx\n" \ | |
615 | " pushq %rbp\n" \ | |
616 | " pushq %r12\n" \ | |
617 | " pushq %r13\n" \ | |
618 | " pushq %r14\n" \ | |
619 | " pushq %r15\n" | |
620 | #define RESTORE_REGS_STRING \ | |
621 | " popq %r15\n" \ | |
622 | " popq %r14\n" \ | |
623 | " popq %r13\n" \ | |
624 | " popq %r12\n" \ | |
625 | " popq %rbp\n" \ | |
626 | " popq %rbx\n" \ | |
627 | " popq %r11\n" \ | |
628 | " popq %r10\n" \ | |
629 | " popq %r9\n" \ | |
630 | " popq %r8\n" \ | |
631 | " popq %rax\n" \ | |
632 | " popq %rcx\n" \ | |
633 | " popq %rdx\n" \ | |
634 | " popq %rsi\n" \ | |
635 | " popq %rdi\n" \ | |
636 | /* Skip orig_ax, ip, cs */ \ | |
637 | " addq $24, %rsp\n" | |
638 | #else | |
639 | #define SAVE_REGS_STRING \ | |
640 | /* Skip cs, ip, orig_ax and gs. */ \ | |
641 | " subl $16, %esp\n" \ | |
642 | " pushl %fs\n" \ | |
643 | " pushl %ds\n" \ | |
644 | " pushl %es\n" \ | |
645 | " pushl %eax\n" \ | |
646 | " pushl %ebp\n" \ | |
647 | " pushl %edi\n" \ | |
648 | " pushl %esi\n" \ | |
649 | " pushl %edx\n" \ | |
650 | " pushl %ecx\n" \ | |
651 | " pushl %ebx\n" | |
652 | #define RESTORE_REGS_STRING \ | |
653 | " popl %ebx\n" \ | |
654 | " popl %ecx\n" \ | |
655 | " popl %edx\n" \ | |
656 | " popl %esi\n" \ | |
657 | " popl %edi\n" \ | |
658 | " popl %ebp\n" \ | |
659 | " popl %eax\n" \ | |
660 | /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\ | |
661 | " addl $24, %esp\n" | |
662 | #endif | |
663 | ||
73649dab | 664 | /* |
da07ab03 MH |
665 | * When a retprobed function returns, this code saves registers and |
666 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 667 | */ |
f1452d42 | 668 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 669 | { |
d6be29b8 MH |
670 | asm volatile ( |
671 | ".global kretprobe_trampoline\n" | |
da07ab03 | 672 | "kretprobe_trampoline: \n" |
d6be29b8 | 673 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
674 | /* We don't bother saving the ss register */ |
675 | " pushq %rsp\n" | |
676 | " pushfq\n" | |
f007ea26 | 677 | SAVE_REGS_STRING |
da07ab03 MH |
678 | " movq %rsp, %rdi\n" |
679 | " call trampoline_handler\n" | |
680 | /* Replace saved sp with true return address. */ | |
681 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 682 | RESTORE_REGS_STRING |
da07ab03 | 683 | " popfq\n" |
d6be29b8 MH |
684 | #else |
685 | " pushf\n" | |
f007ea26 | 686 | SAVE_REGS_STRING |
d6be29b8 MH |
687 | " movl %esp, %eax\n" |
688 | " call trampoline_handler\n" | |
689 | /* Move flags to cs */ | |
fee039a1 MH |
690 | " movl 56(%esp), %edx\n" |
691 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 692 | /* Replace saved flags with true return address. */ |
fee039a1 | 693 | " movl %eax, 56(%esp)\n" |
f007ea26 | 694 | RESTORE_REGS_STRING |
d6be29b8 MH |
695 | " popf\n" |
696 | #endif | |
da07ab03 | 697 | " ret\n"); |
1017579a | 698 | } |
73649dab RL |
699 | |
700 | /* | |
da07ab03 | 701 | * Called from kretprobe_trampoline |
73649dab | 702 | */ |
f1452d42 | 703 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 704 | { |
62c27be0 | 705 | struct kretprobe_instance *ri = NULL; |
99219a3f | 706 | struct hlist_head *head, empty_rp; |
62c27be0 | 707 | struct hlist_node *node, *tmp; |
991a51d8 | 708 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 709 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
73649dab | 710 | |
99219a3f | 711 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 712 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 713 | /* fixup registers */ |
d6be29b8 | 714 | #ifdef CONFIG_X86_64 |
da07ab03 | 715 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
716 | #else |
717 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 718 | regs->gs = 0; |
d6be29b8 | 719 | #endif |
da07ab03 | 720 | regs->ip = trampoline_address; |
8533bbe9 | 721 | regs->orig_ax = ~0UL; |
73649dab | 722 | |
ba8af12f RL |
723 | /* |
724 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 725 | * task either because multiple functions in the call path have |
025dfdaf | 726 | * return probes installed on them, and/or more than one |
ba8af12f RL |
727 | * return probe was registered for a target function. |
728 | * | |
729 | * We can handle this because: | |
8533bbe9 | 730 | * - instances are always pushed into the head of the list |
ba8af12f | 731 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
732 | * function, the (chronologically) first instance's ret_addr |
733 | * will be the real return address, and all the rest will | |
734 | * point to kretprobe_trampoline. | |
ba8af12f RL |
735 | */ |
736 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 737 | if (ri->task != current) |
ba8af12f | 738 | /* another task is sharing our hash bucket */ |
62c27be0 | 739 | continue; |
ba8af12f | 740 | |
da07ab03 MH |
741 | if (ri->rp && ri->rp->handler) { |
742 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
743 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 744 | ri->rp->handler(ri, regs); |
da07ab03 MH |
745 | __get_cpu_var(current_kprobe) = NULL; |
746 | } | |
ba8af12f RL |
747 | |
748 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 749 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
750 | |
751 | if (orig_ret_address != trampoline_address) | |
752 | /* | |
753 | * This is the real return address. Any other | |
754 | * instances associated with this task are for | |
755 | * other calls deeper on the call stack | |
756 | */ | |
757 | break; | |
73649dab | 758 | } |
ba8af12f | 759 | |
0f95b7fc | 760 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 761 | |
ef53d9c5 | 762 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 763 | |
99219a3f | 764 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
765 | hlist_del(&ri->hlist); | |
766 | kfree(ri); | |
767 | } | |
da07ab03 | 768 | return (void *)orig_ret_address; |
73649dab RL |
769 | } |
770 | ||
1da177e4 LT |
771 | /* |
772 | * Called after single-stepping. p->addr is the address of the | |
773 | * instruction whose first byte has been replaced by the "int 3" | |
774 | * instruction. To avoid the SMP problems that can occur when we | |
775 | * temporarily put back the original opcode to single-step, we | |
776 | * single-stepped a copy of the instruction. The address of this | |
777 | * copy is p->ainsn.insn. | |
778 | * | |
779 | * This function prepares to return from the post-single-step | |
780 | * interrupt. We have to fix up the stack as follows: | |
781 | * | |
782 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 783 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
784 | * it relative to the original instruction. |
785 | * | |
786 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 787 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
788 | * |
789 | * 2) If the single-stepped instruction was a call, the return address | |
790 | * that is atop the stack is the address following the copied instruction. | |
791 | * We need to make it the address following the original instruction. | |
aa470140 MH |
792 | * |
793 | * If this is the first time we've single-stepped the instruction at | |
794 | * this probepoint, and the instruction is boostable, boost it: add a | |
795 | * jump instruction after the copied instruction, that jumps to the next | |
796 | * instruction after the probepoint. | |
1da177e4 | 797 | */ |
e7a510f9 AM |
798 | static void __kprobes resume_execution(struct kprobe *p, |
799 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 800 | { |
8533bbe9 MH |
801 | unsigned long *tos = stack_addr(regs); |
802 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
803 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
804 | kprobe_opcode_t *insn = p->ainsn.insn; |
805 | ||
806 | /*skip the REX prefix*/ | |
9930927f | 807 | if (is_REX_prefix(insn)) |
1da177e4 LT |
808 | insn++; |
809 | ||
053de044 | 810 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 811 | switch (*insn) { |
0b0122fa | 812 | case 0x9c: /* pushfl */ |
053de044 | 813 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 814 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 815 | break; |
0b0122fa MH |
816 | case 0xc2: /* iret/ret/lret */ |
817 | case 0xc3: | |
0b9e2cac | 818 | case 0xca: |
0b0122fa MH |
819 | case 0xcb: |
820 | case 0xcf: | |
821 | case 0xea: /* jmp absolute -- ip is correct */ | |
822 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 823 | p->ainsn.boostable = 1; |
0b0122fa MH |
824 | goto no_change; |
825 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 826 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 827 | break; |
e7b5e11e | 828 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
829 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
830 | *tos = orig_ip + (*tos - copy_ip); | |
831 | goto no_change; | |
832 | #endif | |
1da177e4 | 833 | case 0xff: |
dc49e344 | 834 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
835 | /* |
836 | * call absolute, indirect | |
837 | * Fix return addr; ip is correct. | |
838 | * But this is not boostable | |
839 | */ | |
840 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 841 | goto no_change; |
8533bbe9 MH |
842 | } else if (((insn[1] & 0x31) == 0x20) || |
843 | ((insn[1] & 0x31) == 0x21)) { | |
844 | /* | |
845 | * jmp near and far, absolute indirect | |
846 | * ip is correct. And this is boostable | |
847 | */ | |
aa470140 | 848 | p->ainsn.boostable = 1; |
0b0122fa | 849 | goto no_change; |
1da177e4 | 850 | } |
1da177e4 LT |
851 | default: |
852 | break; | |
853 | } | |
854 | ||
aa470140 | 855 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
856 | if ((regs->ip > copy_ip) && |
857 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
858 | /* |
859 | * These instructions can be executed directly if it | |
860 | * jumps back to correct address. | |
861 | */ | |
c0f7ac3a MH |
862 | synthesize_reljump((void *)regs->ip, |
863 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
864 | p->ainsn.boostable = 1; |
865 | } else { | |
866 | p->ainsn.boostable = -1; | |
867 | } | |
868 | } | |
869 | ||
8533bbe9 | 870 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 871 | |
0b0122fa | 872 | no_change: |
1ecc798c | 873 | restore_btf(); |
1da177e4 LT |
874 | } |
875 | ||
8533bbe9 MH |
876 | /* |
877 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 878 | * remain disabled throughout this function. |
8533bbe9 MH |
879 | */ |
880 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 881 | { |
e7a510f9 AM |
882 | struct kprobe *cur = kprobe_running(); |
883 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
884 | ||
885 | if (!cur) | |
1da177e4 LT |
886 | return 0; |
887 | ||
acb5b8a2 YL |
888 | resume_execution(cur, regs, kcb); |
889 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 890 | |
e7a510f9 AM |
891 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
892 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
893 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 894 | } |
1da177e4 | 895 | |
8533bbe9 | 896 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
897 | if (kcb->kprobe_status == KPROBE_REENTER) { |
898 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 899 | goto out; |
aa3d7e3d | 900 | } |
e7a510f9 | 901 | reset_current_kprobe(); |
aa3d7e3d | 902 | out: |
1da177e4 LT |
903 | preempt_enable_no_resched(); |
904 | ||
905 | /* | |
65ea5b03 | 906 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
907 | * will have TF set, in which case, continue the remaining processing |
908 | * of do_debug, as if this is not a probe hit. | |
909 | */ | |
053de044 | 910 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
911 | return 0; |
912 | ||
913 | return 1; | |
914 | } | |
915 | ||
0f2fbdcb | 916 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 917 | { |
e7a510f9 AM |
918 | struct kprobe *cur = kprobe_running(); |
919 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
920 | ||
d6be29b8 | 921 | switch (kcb->kprobe_status) { |
c28f8966 PP |
922 | case KPROBE_HIT_SS: |
923 | case KPROBE_REENTER: | |
924 | /* | |
925 | * We are here because the instruction being single | |
926 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 927 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
928 | * and allow the page fault handler to continue as a |
929 | * normal page fault. | |
930 | */ | |
65ea5b03 | 931 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 932 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
933 | if (kcb->kprobe_status == KPROBE_REENTER) |
934 | restore_previous_kprobe(kcb); | |
935 | else | |
936 | reset_current_kprobe(); | |
1da177e4 | 937 | preempt_enable_no_resched(); |
c28f8966 PP |
938 | break; |
939 | case KPROBE_HIT_ACTIVE: | |
940 | case KPROBE_HIT_SSDONE: | |
941 | /* | |
942 | * We increment the nmissed count for accounting, | |
8533bbe9 | 943 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
944 | * these specific fault cases. |
945 | */ | |
946 | kprobes_inc_nmissed_count(cur); | |
947 | ||
948 | /* | |
949 | * We come here because instructions in the pre/post | |
950 | * handler caused the page_fault, this could happen | |
951 | * if handler tries to access user space by | |
952 | * copy_from_user(), get_user() etc. Let the | |
953 | * user-specified handler try to fix it first. | |
954 | */ | |
955 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
956 | return 1; | |
957 | ||
958 | /* | |
959 | * In case the user-specified fault handler returned | |
960 | * zero, try to fix up. | |
961 | */ | |
d6be29b8 MH |
962 | if (fixup_exception(regs)) |
963 | return 1; | |
6d48583b | 964 | |
c28f8966 | 965 | /* |
8533bbe9 | 966 | * fixup routine could not handle it, |
c28f8966 PP |
967 | * Let do_page_fault() fix it. |
968 | */ | |
969 | break; | |
970 | default: | |
971 | break; | |
1da177e4 LT |
972 | } |
973 | return 0; | |
974 | } | |
975 | ||
976 | /* | |
977 | * Wrapper routine for handling exceptions. | |
978 | */ | |
0f2fbdcb PP |
979 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
980 | unsigned long val, void *data) | |
1da177e4 | 981 | { |
ade1af77 | 982 | struct die_args *args = data; |
66ff2d06 AM |
983 | int ret = NOTIFY_DONE; |
984 | ||
8533bbe9 | 985 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 986 | return ret; |
987 | ||
1da177e4 LT |
988 | switch (val) { |
989 | case DIE_INT3: | |
990 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 991 | ret = NOTIFY_STOP; |
1da177e4 LT |
992 | break; |
993 | case DIE_DEBUG: | |
62edab90 P |
994 | if (post_kprobe_handler(args->regs)) { |
995 | /* | |
996 | * Reset the BS bit in dr6 (pointed by args->err) to | |
997 | * denote completion of processing | |
998 | */ | |
999 | (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; | |
66ff2d06 | 1000 | ret = NOTIFY_STOP; |
62edab90 | 1001 | } |
1da177e4 LT |
1002 | break; |
1003 | case DIE_GPF: | |
b506a9d0 QB |
1004 | /* |
1005 | * To be potentially processing a kprobe fault and to | |
1006 | * trust the result from kprobe_running(), we have | |
1007 | * be non-preemptible. | |
1008 | */ | |
1009 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1010 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1011 | ret = NOTIFY_STOP; |
1da177e4 LT |
1012 | break; |
1013 | default: | |
1014 | break; | |
1015 | } | |
66ff2d06 | 1016 | return ret; |
1da177e4 LT |
1017 | } |
1018 | ||
0f2fbdcb | 1019 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1020 | { |
1021 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1022 | unsigned long addr; | |
e7a510f9 | 1023 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1024 | |
e7a510f9 | 1025 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1026 | kcb->jprobe_saved_sp = stack_addr(regs); |
1027 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1028 | ||
1da177e4 LT |
1029 | /* |
1030 | * As Linus pointed out, gcc assumes that the callee | |
1031 | * owns the argument space and could overwrite it, e.g. | |
1032 | * tailcall optimization. So, to be absolutely safe | |
1033 | * we also save and restore enough stack bytes to cover | |
1034 | * the argument area. | |
1035 | */ | |
e7a510f9 | 1036 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1037 | MIN_STACK_SIZE(addr)); |
053de044 | 1038 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1039 | trace_hardirqs_off(); |
65ea5b03 | 1040 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
1041 | return 1; |
1042 | } | |
1043 | ||
0f2fbdcb | 1044 | void __kprobes jprobe_return(void) |
1da177e4 | 1045 | { |
e7a510f9 AM |
1046 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1047 | ||
d6be29b8 MH |
1048 | asm volatile ( |
1049 | #ifdef CONFIG_X86_64 | |
1050 | " xchg %%rbx,%%rsp \n" | |
1051 | #else | |
1052 | " xchgl %%ebx,%%esp \n" | |
1053 | #endif | |
1054 | " int3 \n" | |
1055 | " .globl jprobe_return_end\n" | |
1056 | " jprobe_return_end: \n" | |
1057 | " nop \n"::"b" | |
1058 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1059 | } |
1060 | ||
0f2fbdcb | 1061 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1062 | { |
e7a510f9 | 1063 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1064 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1065 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1066 | ||
d6be29b8 MH |
1067 | if ((addr > (u8 *) jprobe_return) && |
1068 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1069 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1070 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1071 | printk(KERN_ERR |
1072 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1073 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1074 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1075 | show_registers(saved_regs); |
d6be29b8 | 1076 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1077 | show_registers(regs); |
1078 | BUG(); | |
1079 | } | |
e7a510f9 | 1080 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1081 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1082 | kcb->jprobes_stack, | |
1083 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1084 | preempt_enable_no_resched(); |
1da177e4 LT |
1085 | return 1; |
1086 | } | |
1087 | return 0; | |
1088 | } | |
ba8af12f | 1089 | |
c0f7ac3a MH |
1090 | |
1091 | #ifdef CONFIG_OPTPROBES | |
1092 | ||
1093 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ | |
1094 | static void __kprobes synthesize_relcall(void *from, void *to) | |
1095 | { | |
1096 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
1097 | } | |
1098 | ||
1099 | /* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */ | |
1100 | static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, | |
1101 | unsigned long val) | |
1102 | { | |
1103 | #ifdef CONFIG_X86_64 | |
1104 | *addr++ = 0x48; | |
1105 | *addr++ = 0xbf; | |
1106 | #else | |
1107 | *addr++ = 0xb8; | |
1108 | #endif | |
1109 | *(unsigned long *)addr = val; | |
1110 | } | |
1111 | ||
1112 | void __kprobes kprobes_optinsn_template_holder(void) | |
1113 | { | |
1114 | asm volatile ( | |
1115 | ".global optprobe_template_entry\n" | |
1116 | "optprobe_template_entry: \n" | |
1117 | #ifdef CONFIG_X86_64 | |
1118 | /* We don't bother saving the ss register */ | |
1119 | " pushq %rsp\n" | |
1120 | " pushfq\n" | |
1121 | SAVE_REGS_STRING | |
1122 | " movq %rsp, %rsi\n" | |
1123 | ".global optprobe_template_val\n" | |
1124 | "optprobe_template_val: \n" | |
1125 | ASM_NOP5 | |
1126 | ASM_NOP5 | |
1127 | ".global optprobe_template_call\n" | |
1128 | "optprobe_template_call: \n" | |
1129 | ASM_NOP5 | |
1130 | /* Move flags to rsp */ | |
1131 | " movq 144(%rsp), %rdx\n" | |
1132 | " movq %rdx, 152(%rsp)\n" | |
1133 | RESTORE_REGS_STRING | |
1134 | /* Skip flags entry */ | |
1135 | " addq $8, %rsp\n" | |
1136 | " popfq\n" | |
1137 | #else /* CONFIG_X86_32 */ | |
1138 | " pushf\n" | |
1139 | SAVE_REGS_STRING | |
1140 | " movl %esp, %edx\n" | |
1141 | ".global optprobe_template_val\n" | |
1142 | "optprobe_template_val: \n" | |
1143 | ASM_NOP5 | |
1144 | ".global optprobe_template_call\n" | |
1145 | "optprobe_template_call: \n" | |
1146 | ASM_NOP5 | |
1147 | RESTORE_REGS_STRING | |
1148 | " addl $4, %esp\n" /* skip cs */ | |
1149 | " popf\n" | |
1150 | #endif | |
1151 | ".global optprobe_template_end\n" | |
1152 | "optprobe_template_end: \n"); | |
1153 | } | |
1154 | ||
1155 | #define TMPL_MOVE_IDX \ | |
1156 | ((long)&optprobe_template_val - (long)&optprobe_template_entry) | |
1157 | #define TMPL_CALL_IDX \ | |
1158 | ((long)&optprobe_template_call - (long)&optprobe_template_entry) | |
1159 | #define TMPL_END_IDX \ | |
1160 | ((long)&optprobe_template_end - (long)&optprobe_template_entry) | |
1161 | ||
1162 | #define INT3_SIZE sizeof(kprobe_opcode_t) | |
1163 | ||
1164 | /* Optimized kprobe call back function: called from optinsn */ | |
1165 | static void __kprobes optimized_callback(struct optimized_kprobe *op, | |
1166 | struct pt_regs *regs) | |
1167 | { | |
1168 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
1169 | ||
1170 | preempt_disable(); | |
1171 | if (kprobe_running()) { | |
1172 | kprobes_inc_nmissed_count(&op->kp); | |
1173 | } else { | |
1174 | /* Save skipped registers */ | |
1175 | #ifdef CONFIG_X86_64 | |
1176 | regs->cs = __KERNEL_CS; | |
1177 | #else | |
1178 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
1179 | regs->gs = 0; | |
1180 | #endif | |
1181 | regs->ip = (unsigned long)op->kp.addr + INT3_SIZE; | |
1182 | regs->orig_ax = ~0UL; | |
1183 | ||
1184 | __get_cpu_var(current_kprobe) = &op->kp; | |
1185 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1186 | opt_pre_handler(&op->kp, regs); | |
1187 | __get_cpu_var(current_kprobe) = NULL; | |
1188 | } | |
1189 | preempt_enable_no_resched(); | |
1190 | } | |
1191 | ||
1192 | static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src) | |
1193 | { | |
1194 | int len = 0, ret; | |
1195 | ||
1196 | while (len < RELATIVEJUMP_SIZE) { | |
1197 | ret = __copy_instruction(dest + len, src + len, 1); | |
1198 | if (!ret || !can_boost(dest + len)) | |
1199 | return -EINVAL; | |
1200 | len += ret; | |
1201 | } | |
1202 | /* Check whether the address range is reserved */ | |
1203 | if (ftrace_text_reserved(src, src + len - 1) || | |
1204 | alternatives_text_reserved(src, src + len - 1)) | |
1205 | return -EBUSY; | |
1206 | ||
1207 | return len; | |
1208 | } | |
1209 | ||
1210 | /* Check whether insn is indirect jump */ | |
1211 | static int __kprobes insn_is_indirect_jump(struct insn *insn) | |
1212 | { | |
1213 | return ((insn->opcode.bytes[0] == 0xff && | |
1214 | (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */ | |
1215 | insn->opcode.bytes[0] == 0xea); /* Segment based jump */ | |
1216 | } | |
1217 | ||
1218 | /* Check whether insn jumps into specified address range */ | |
1219 | static int insn_jump_into_range(struct insn *insn, unsigned long start, int len) | |
1220 | { | |
1221 | unsigned long target = 0; | |
1222 | ||
1223 | switch (insn->opcode.bytes[0]) { | |
1224 | case 0xe0: /* loopne */ | |
1225 | case 0xe1: /* loope */ | |
1226 | case 0xe2: /* loop */ | |
1227 | case 0xe3: /* jcxz */ | |
1228 | case 0xe9: /* near relative jump */ | |
1229 | case 0xeb: /* short relative jump */ | |
1230 | break; | |
1231 | case 0x0f: | |
1232 | if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */ | |
1233 | break; | |
1234 | return 0; | |
1235 | default: | |
1236 | if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */ | |
1237 | break; | |
1238 | return 0; | |
1239 | } | |
1240 | target = (unsigned long)insn->next_byte + insn->immediate.value; | |
1241 | ||
1242 | return (start <= target && target <= start + len); | |
1243 | } | |
1244 | ||
1245 | /* Decode whole function to ensure any instructions don't jump into target */ | |
1246 | static int __kprobes can_optimize(unsigned long paddr) | |
1247 | { | |
1248 | int ret; | |
1249 | unsigned long addr, size = 0, offset = 0; | |
1250 | struct insn insn; | |
1251 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
1252 | /* Dummy buffers for lookup_symbol_attrs */ | |
1253 | static char __dummy_buf[KSYM_NAME_LEN]; | |
1254 | ||
1255 | /* Lookup symbol including addr */ | |
1256 | if (!kallsyms_lookup(paddr, &size, &offset, NULL, __dummy_buf)) | |
1257 | return 0; | |
1258 | ||
1259 | /* Check there is enough space for a relative jump. */ | |
1260 | if (size - offset < RELATIVEJUMP_SIZE) | |
1261 | return 0; | |
1262 | ||
1263 | /* Decode instructions */ | |
1264 | addr = paddr - offset; | |
1265 | while (addr < paddr - offset + size) { /* Decode until function end */ | |
1266 | if (search_exception_tables(addr)) | |
1267 | /* | |
1268 | * Since some fixup code will jumps into this function, | |
1269 | * we can't optimize kprobe in this function. | |
1270 | */ | |
1271 | return 0; | |
1272 | kernel_insn_init(&insn, (void *)addr); | |
1273 | insn_get_opcode(&insn); | |
1274 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
1275 | ret = recover_probed_instruction(buf, addr); | |
1276 | if (ret) | |
1277 | return 0; | |
1278 | kernel_insn_init(&insn, buf); | |
1279 | } | |
1280 | insn_get_length(&insn); | |
1281 | /* Recover address */ | |
1282 | insn.kaddr = (void *)addr; | |
1283 | insn.next_byte = (void *)(addr + insn.length); | |
1284 | /* Check any instructions don't jump into target */ | |
1285 | if (insn_is_indirect_jump(&insn) || | |
1286 | insn_jump_into_range(&insn, paddr + INT3_SIZE, | |
1287 | RELATIVE_ADDR_SIZE)) | |
1288 | return 0; | |
1289 | addr += insn.length; | |
1290 | } | |
1291 | ||
1292 | return 1; | |
1293 | } | |
1294 | ||
1295 | /* Check optimized_kprobe can actually be optimized. */ | |
1296 | int __kprobes arch_check_optimized_kprobe(struct optimized_kprobe *op) | |
1297 | { | |
1298 | int i; | |
1299 | struct kprobe *p; | |
1300 | ||
1301 | for (i = 1; i < op->optinsn.size; i++) { | |
1302 | p = get_kprobe(op->kp.addr + i); | |
1303 | if (p && !kprobe_disabled(p)) | |
1304 | return -EEXIST; | |
1305 | } | |
1306 | ||
1307 | return 0; | |
1308 | } | |
1309 | ||
1310 | /* Check the addr is within the optimized instructions. */ | |
1311 | int __kprobes arch_within_optimized_kprobe(struct optimized_kprobe *op, | |
1312 | unsigned long addr) | |
1313 | { | |
1314 | return ((unsigned long)op->kp.addr <= addr && | |
1315 | (unsigned long)op->kp.addr + op->optinsn.size > addr); | |
1316 | } | |
1317 | ||
1318 | /* Free optimized instruction slot */ | |
1319 | static __kprobes | |
1320 | void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty) | |
1321 | { | |
1322 | if (op->optinsn.insn) { | |
1323 | free_optinsn_slot(op->optinsn.insn, dirty); | |
1324 | op->optinsn.insn = NULL; | |
1325 | op->optinsn.size = 0; | |
1326 | } | |
1327 | } | |
1328 | ||
1329 | void __kprobes arch_remove_optimized_kprobe(struct optimized_kprobe *op) | |
1330 | { | |
1331 | __arch_remove_optimized_kprobe(op, 1); | |
1332 | } | |
1333 | ||
1334 | /* | |
1335 | * Copy replacing target instructions | |
1336 | * Target instructions MUST be relocatable (checked inside) | |
1337 | */ | |
1338 | int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op) | |
1339 | { | |
1340 | u8 *buf; | |
1341 | int ret; | |
1342 | long rel; | |
1343 | ||
1344 | if (!can_optimize((unsigned long)op->kp.addr)) | |
1345 | return -EILSEQ; | |
1346 | ||
1347 | op->optinsn.insn = get_optinsn_slot(); | |
1348 | if (!op->optinsn.insn) | |
1349 | return -ENOMEM; | |
1350 | ||
1351 | /* | |
1352 | * Verify if the address gap is in 2GB range, because this uses | |
1353 | * a relative jump. | |
1354 | */ | |
1355 | rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE; | |
1356 | if (abs(rel) > 0x7fffffff) | |
1357 | return -ERANGE; | |
1358 | ||
1359 | buf = (u8 *)op->optinsn.insn; | |
1360 | ||
1361 | /* Copy instructions into the out-of-line buffer */ | |
1362 | ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr); | |
1363 | if (ret < 0) { | |
1364 | __arch_remove_optimized_kprobe(op, 0); | |
1365 | return ret; | |
1366 | } | |
1367 | op->optinsn.size = ret; | |
1368 | ||
1369 | /* Copy arch-dep-instance from template */ | |
1370 | memcpy(buf, &optprobe_template_entry, TMPL_END_IDX); | |
1371 | ||
1372 | /* Set probe information */ | |
1373 | synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op); | |
1374 | ||
1375 | /* Set probe function call */ | |
1376 | synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback); | |
1377 | ||
1378 | /* Set returning jmp instruction at the tail of out-of-line buffer */ | |
1379 | synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size, | |
1380 | (u8 *)op->kp.addr + op->optinsn.size); | |
1381 | ||
1382 | flush_icache_range((unsigned long) buf, | |
1383 | (unsigned long) buf + TMPL_END_IDX + | |
1384 | op->optinsn.size + RELATIVEJUMP_SIZE); | |
1385 | return 0; | |
1386 | } | |
1387 | ||
1388 | /* Replace a breakpoint (int3) with a relative jump. */ | |
1389 | int __kprobes arch_optimize_kprobe(struct optimized_kprobe *op) | |
1390 | { | |
1391 | unsigned char jmp_code[RELATIVEJUMP_SIZE]; | |
1392 | s32 rel = (s32)((long)op->optinsn.insn - | |
1393 | ((long)op->kp.addr + RELATIVEJUMP_SIZE)); | |
1394 | ||
1395 | /* Backup instructions which will be replaced by jump address */ | |
1396 | memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE, | |
1397 | RELATIVE_ADDR_SIZE); | |
1398 | ||
1399 | jmp_code[0] = RELATIVEJUMP_OPCODE; | |
1400 | *(s32 *)(&jmp_code[1]) = rel; | |
1401 | ||
1402 | /* | |
1403 | * text_poke_smp doesn't support NMI/MCE code modifying. | |
1404 | * However, since kprobes itself also doesn't support NMI/MCE | |
1405 | * code probing, it's not a problem. | |
1406 | */ | |
1407 | text_poke_smp(op->kp.addr, jmp_code, RELATIVEJUMP_SIZE); | |
1408 | return 0; | |
1409 | } | |
1410 | ||
1411 | /* Replace a relative jump with a breakpoint (int3). */ | |
1412 | void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op) | |
1413 | { | |
1414 | u8 buf[RELATIVEJUMP_SIZE]; | |
1415 | ||
1416 | /* Set int3 to first byte for kprobes */ | |
1417 | buf[0] = BREAKPOINT_INSTRUCTION; | |
1418 | memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); | |
1419 | text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE); | |
1420 | } | |
1421 | ||
1422 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
1423 | struct pt_regs *regs, | |
1424 | int reenter) | |
1425 | { | |
1426 | struct optimized_kprobe *op; | |
1427 | ||
1428 | if (p->flags & KPROBE_FLAG_OPTIMIZED) { | |
1429 | /* This kprobe is really able to run optimized path. */ | |
1430 | op = container_of(p, struct optimized_kprobe, kp); | |
1431 | /* Detour through copied instructions */ | |
1432 | regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX; | |
1433 | if (!reenter) | |
1434 | reset_current_kprobe(); | |
1435 | preempt_enable_no_resched(); | |
1436 | return 1; | |
1437 | } | |
1438 | return 0; | |
1439 | } | |
1440 | #endif | |
1441 | ||
6772926b | 1442 | int __init arch_init_kprobes(void) |
ba8af12f | 1443 | { |
da07ab03 | 1444 | return 0; |
ba8af12f | 1445 | } |
bf8f6e5b AM |
1446 | |
1447 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1448 | { | |
bf8f6e5b AM |
1449 | return 0; |
1450 | } |