Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
1da177e4 LT |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2002, 2004 | |
19 | * | |
20 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel | |
21 | * Probes initial implementation ( includes contributions from | |
22 | * Rusty Russell). | |
23 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes | |
24 | * interface to access function arguments. | |
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 RM |
424 | { |
425 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 426 | update_debugctlmsr(0); |
1ecc798c RM |
427 | } |
428 | ||
e7b5e11e | 429 | static void __kprobes restore_btf(void) |
1ecc798c RM |
430 | { |
431 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 432 | update_debugctlmsr(current->thread.debugctlmsr); |
1ecc798c RM |
433 | } |
434 | ||
4c4308cb | 435 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 436 | struct pt_regs *regs) |
73649dab | 437 | { |
8533bbe9 | 438 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 439 | |
4c4308cb | 440 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 441 | |
4c4308cb CH |
442 | /* Replace the return addr with trampoline addr */ |
443 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 444 | } |
f315decb | 445 | |
c0f7ac3a MH |
446 | #ifdef CONFIG_OPTPROBES |
447 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
448 | struct pt_regs *regs, | |
449 | int reenter); | |
450 | #else | |
451 | #define setup_detour_execution(p, regs, reenter) (0) | |
452 | #endif | |
453 | ||
f315decb | 454 | static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
0f94eb63 | 455 | struct kprobe_ctlblk *kcb, int reenter) |
f315decb | 456 | { |
c0f7ac3a MH |
457 | if (setup_detour_execution(p, regs, reenter)) |
458 | return; | |
459 | ||
615d0ebb | 460 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
461 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
462 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
463 | if (!reenter) |
464 | reset_current_kprobe(); | |
465 | /* | |
466 | * Reentering boosted probe doesn't reset current_kprobe, | |
467 | * nor set current_kprobe, because it doesn't use single | |
468 | * stepping. | |
469 | */ | |
f315decb AS |
470 | regs->ip = (unsigned long)p->ainsn.insn; |
471 | preempt_enable_no_resched(); | |
472 | return; | |
473 | } | |
474 | #endif | |
0f94eb63 MH |
475 | if (reenter) { |
476 | save_previous_kprobe(kcb); | |
477 | set_current_kprobe(p, regs, kcb); | |
478 | kcb->kprobe_status = KPROBE_REENTER; | |
479 | } else | |
480 | kcb->kprobe_status = KPROBE_HIT_SS; | |
481 | /* Prepare real single stepping */ | |
482 | clear_btf(); | |
483 | regs->flags |= X86_EFLAGS_TF; | |
484 | regs->flags &= ~X86_EFLAGS_IF; | |
485 | /* single step inline if the instruction is an int3 */ | |
486 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
487 | regs->ip = (unsigned long)p->addr; | |
488 | else | |
489 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb AS |
490 | } |
491 | ||
40102d4a HH |
492 | /* |
493 | * We have reentered the kprobe_handler(), since another probe was hit while | |
494 | * within the handler. We save the original kprobes variables and just single | |
495 | * step on the instruction of the new probe without calling any user handlers. | |
496 | */ | |
59e87cdc MH |
497 | static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
498 | struct kprobe_ctlblk *kcb) | |
40102d4a | 499 | { |
f315decb AS |
500 | switch (kcb->kprobe_status) { |
501 | case KPROBE_HIT_SSDONE: | |
f315decb | 502 | case KPROBE_HIT_ACTIVE: |
fb8830e7 | 503 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 504 | setup_singlestep(p, regs, kcb, 1); |
f315decb AS |
505 | break; |
506 | case KPROBE_HIT_SS: | |
e9afe9e1 MH |
507 | /* A probe has been hit in the codepath leading up to, or just |
508 | * after, single-stepping of a probed instruction. This entire | |
509 | * codepath should strictly reside in .kprobes.text section. | |
510 | * Raise a BUG or we'll continue in an endless reentering loop | |
511 | * and eventually a stack overflow. | |
512 | */ | |
513 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
514 | p->addr); | |
515 | dump_kprobe(p); | |
516 | BUG(); | |
f315decb AS |
517 | default: |
518 | /* impossible cases */ | |
519 | WARN_ON(1); | |
fb8830e7 | 520 | return 0; |
59e87cdc | 521 | } |
f315decb | 522 | |
59e87cdc | 523 | return 1; |
40102d4a | 524 | } |
73649dab | 525 | |
8533bbe9 MH |
526 | /* |
527 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 528 | * remain disabled throughout this function. |
8533bbe9 MH |
529 | */ |
530 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 531 | { |
8533bbe9 | 532 | kprobe_opcode_t *addr; |
f315decb | 533 | struct kprobe *p; |
d217d545 AM |
534 | struct kprobe_ctlblk *kcb; |
535 | ||
8533bbe9 | 536 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
f315decb AS |
537 | if (*addr != BREAKPOINT_INSTRUCTION) { |
538 | /* | |
539 | * The breakpoint instruction was removed right | |
540 | * after we hit it. Another cpu has removed | |
541 | * either a probepoint or a debugger breakpoint | |
542 | * at this address. In either case, no further | |
543 | * handling of this interrupt is appropriate. | |
544 | * Back up over the (now missing) int3 and run | |
545 | * the original instruction. | |
546 | */ | |
547 | regs->ip = (unsigned long)addr; | |
548 | return 1; | |
549 | } | |
8533bbe9 | 550 | |
d217d545 AM |
551 | /* |
552 | * We don't want to be preempted for the entire | |
f315decb AS |
553 | * duration of kprobe processing. We conditionally |
554 | * re-enable preemption at the end of this function, | |
555 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
556 | */ |
557 | preempt_disable(); | |
1da177e4 | 558 | |
f315decb | 559 | kcb = get_kprobe_ctlblk(); |
b9760156 | 560 | p = get_kprobe(addr); |
f315decb | 561 | |
b9760156 | 562 | if (p) { |
b9760156 | 563 | if (kprobe_running()) { |
f315decb AS |
564 | if (reenter_kprobe(p, regs, kcb)) |
565 | return 1; | |
1da177e4 | 566 | } else { |
b9760156 HH |
567 | set_current_kprobe(p, regs, kcb); |
568 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 569 | |
1da177e4 | 570 | /* |
f315decb AS |
571 | * If we have no pre-handler or it returned 0, we |
572 | * continue with normal processing. If we have a | |
573 | * pre-handler and it returned non-zero, it prepped | |
574 | * for calling the break_handler below on re-entry | |
575 | * for jprobe processing, so get out doing nothing | |
576 | * more here. | |
1da177e4 | 577 | */ |
f315decb | 578 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 579 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 580 | return 1; |
b9760156 | 581 | } |
f315decb AS |
582 | } else if (kprobe_running()) { |
583 | p = __get_cpu_var(current_kprobe); | |
584 | if (p->break_handler && p->break_handler(p, regs)) { | |
0f94eb63 | 585 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 586 | return 1; |
1da177e4 | 587 | } |
f315decb | 588 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 589 | |
d217d545 | 590 | preempt_enable_no_resched(); |
f315decb | 591 | return 0; |
1da177e4 LT |
592 | } |
593 | ||
f007ea26 MH |
594 | #ifdef CONFIG_X86_64 |
595 | #define SAVE_REGS_STRING \ | |
596 | /* Skip cs, ip, orig_ax. */ \ | |
597 | " subq $24, %rsp\n" \ | |
598 | " pushq %rdi\n" \ | |
599 | " pushq %rsi\n" \ | |
600 | " pushq %rdx\n" \ | |
601 | " pushq %rcx\n" \ | |
602 | " pushq %rax\n" \ | |
603 | " pushq %r8\n" \ | |
604 | " pushq %r9\n" \ | |
605 | " pushq %r10\n" \ | |
606 | " pushq %r11\n" \ | |
607 | " pushq %rbx\n" \ | |
608 | " pushq %rbp\n" \ | |
609 | " pushq %r12\n" \ | |
610 | " pushq %r13\n" \ | |
611 | " pushq %r14\n" \ | |
612 | " pushq %r15\n" | |
613 | #define RESTORE_REGS_STRING \ | |
614 | " popq %r15\n" \ | |
615 | " popq %r14\n" \ | |
616 | " popq %r13\n" \ | |
617 | " popq %r12\n" \ | |
618 | " popq %rbp\n" \ | |
619 | " popq %rbx\n" \ | |
620 | " popq %r11\n" \ | |
621 | " popq %r10\n" \ | |
622 | " popq %r9\n" \ | |
623 | " popq %r8\n" \ | |
624 | " popq %rax\n" \ | |
625 | " popq %rcx\n" \ | |
626 | " popq %rdx\n" \ | |
627 | " popq %rsi\n" \ | |
628 | " popq %rdi\n" \ | |
629 | /* Skip orig_ax, ip, cs */ \ | |
630 | " addq $24, %rsp\n" | |
631 | #else | |
632 | #define SAVE_REGS_STRING \ | |
633 | /* Skip cs, ip, orig_ax and gs. */ \ | |
634 | " subl $16, %esp\n" \ | |
635 | " pushl %fs\n" \ | |
636 | " pushl %ds\n" \ | |
637 | " pushl %es\n" \ | |
638 | " pushl %eax\n" \ | |
639 | " pushl %ebp\n" \ | |
640 | " pushl %edi\n" \ | |
641 | " pushl %esi\n" \ | |
642 | " pushl %edx\n" \ | |
643 | " pushl %ecx\n" \ | |
644 | " pushl %ebx\n" | |
645 | #define RESTORE_REGS_STRING \ | |
646 | " popl %ebx\n" \ | |
647 | " popl %ecx\n" \ | |
648 | " popl %edx\n" \ | |
649 | " popl %esi\n" \ | |
650 | " popl %edi\n" \ | |
651 | " popl %ebp\n" \ | |
652 | " popl %eax\n" \ | |
653 | /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\ | |
654 | " addl $24, %esp\n" | |
655 | #endif | |
656 | ||
73649dab | 657 | /* |
da07ab03 MH |
658 | * When a retprobed function returns, this code saves registers and |
659 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 660 | */ |
f1452d42 | 661 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 662 | { |
d6be29b8 MH |
663 | asm volatile ( |
664 | ".global kretprobe_trampoline\n" | |
da07ab03 | 665 | "kretprobe_trampoline: \n" |
d6be29b8 | 666 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
667 | /* We don't bother saving the ss register */ |
668 | " pushq %rsp\n" | |
669 | " pushfq\n" | |
f007ea26 | 670 | SAVE_REGS_STRING |
da07ab03 MH |
671 | " movq %rsp, %rdi\n" |
672 | " call trampoline_handler\n" | |
673 | /* Replace saved sp with true return address. */ | |
674 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 675 | RESTORE_REGS_STRING |
da07ab03 | 676 | " popfq\n" |
d6be29b8 MH |
677 | #else |
678 | " pushf\n" | |
f007ea26 | 679 | SAVE_REGS_STRING |
d6be29b8 MH |
680 | " movl %esp, %eax\n" |
681 | " call trampoline_handler\n" | |
682 | /* Move flags to cs */ | |
fee039a1 MH |
683 | " movl 56(%esp), %edx\n" |
684 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 685 | /* Replace saved flags with true return address. */ |
fee039a1 | 686 | " movl %eax, 56(%esp)\n" |
f007ea26 | 687 | RESTORE_REGS_STRING |
d6be29b8 MH |
688 | " popf\n" |
689 | #endif | |
da07ab03 | 690 | " ret\n"); |
1017579a | 691 | } |
73649dab RL |
692 | |
693 | /* | |
da07ab03 | 694 | * Called from kretprobe_trampoline |
73649dab | 695 | */ |
f1452d42 | 696 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 697 | { |
62c27be0 | 698 | struct kretprobe_instance *ri = NULL; |
99219a3f | 699 | struct hlist_head *head, empty_rp; |
62c27be0 | 700 | struct hlist_node *node, *tmp; |
991a51d8 | 701 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 702 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
73649dab | 703 | |
99219a3f | 704 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 705 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 706 | /* fixup registers */ |
d6be29b8 | 707 | #ifdef CONFIG_X86_64 |
da07ab03 | 708 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
709 | #else |
710 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 711 | regs->gs = 0; |
d6be29b8 | 712 | #endif |
da07ab03 | 713 | regs->ip = trampoline_address; |
8533bbe9 | 714 | regs->orig_ax = ~0UL; |
73649dab | 715 | |
ba8af12f RL |
716 | /* |
717 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 718 | * task either because multiple functions in the call path have |
025dfdaf | 719 | * return probes installed on them, and/or more than one |
ba8af12f RL |
720 | * return probe was registered for a target function. |
721 | * | |
722 | * We can handle this because: | |
8533bbe9 | 723 | * - instances are always pushed into the head of the list |
ba8af12f | 724 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
725 | * function, the (chronologically) first instance's ret_addr |
726 | * will be the real return address, and all the rest will | |
727 | * point to kretprobe_trampoline. | |
ba8af12f RL |
728 | */ |
729 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 730 | if (ri->task != current) |
ba8af12f | 731 | /* another task is sharing our hash bucket */ |
62c27be0 | 732 | continue; |
ba8af12f | 733 | |
da07ab03 MH |
734 | if (ri->rp && ri->rp->handler) { |
735 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
736 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 737 | ri->rp->handler(ri, regs); |
da07ab03 MH |
738 | __get_cpu_var(current_kprobe) = NULL; |
739 | } | |
ba8af12f RL |
740 | |
741 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 742 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
743 | |
744 | if (orig_ret_address != trampoline_address) | |
745 | /* | |
746 | * This is the real return address. Any other | |
747 | * instances associated with this task are for | |
748 | * other calls deeper on the call stack | |
749 | */ | |
750 | break; | |
73649dab | 751 | } |
ba8af12f | 752 | |
0f95b7fc | 753 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 754 | |
ef53d9c5 | 755 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 756 | |
99219a3f | 757 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
758 | hlist_del(&ri->hlist); | |
759 | kfree(ri); | |
760 | } | |
da07ab03 | 761 | return (void *)orig_ret_address; |
73649dab RL |
762 | } |
763 | ||
1da177e4 LT |
764 | /* |
765 | * Called after single-stepping. p->addr is the address of the | |
766 | * instruction whose first byte has been replaced by the "int 3" | |
767 | * instruction. To avoid the SMP problems that can occur when we | |
768 | * temporarily put back the original opcode to single-step, we | |
769 | * single-stepped a copy of the instruction. The address of this | |
770 | * copy is p->ainsn.insn. | |
771 | * | |
772 | * This function prepares to return from the post-single-step | |
773 | * interrupt. We have to fix up the stack as follows: | |
774 | * | |
775 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 776 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
777 | * it relative to the original instruction. |
778 | * | |
779 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 780 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
781 | * |
782 | * 2) If the single-stepped instruction was a call, the return address | |
783 | * that is atop the stack is the address following the copied instruction. | |
784 | * We need to make it the address following the original instruction. | |
aa470140 MH |
785 | * |
786 | * If this is the first time we've single-stepped the instruction at | |
787 | * this probepoint, and the instruction is boostable, boost it: add a | |
788 | * jump instruction after the copied instruction, that jumps to the next | |
789 | * instruction after the probepoint. | |
1da177e4 | 790 | */ |
e7a510f9 AM |
791 | static void __kprobes resume_execution(struct kprobe *p, |
792 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 793 | { |
8533bbe9 MH |
794 | unsigned long *tos = stack_addr(regs); |
795 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
796 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
797 | kprobe_opcode_t *insn = p->ainsn.insn; |
798 | ||
799 | /*skip the REX prefix*/ | |
9930927f | 800 | if (is_REX_prefix(insn)) |
1da177e4 LT |
801 | insn++; |
802 | ||
053de044 | 803 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 804 | switch (*insn) { |
0b0122fa | 805 | case 0x9c: /* pushfl */ |
053de044 | 806 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 807 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 808 | break; |
0b0122fa MH |
809 | case 0xc2: /* iret/ret/lret */ |
810 | case 0xc3: | |
0b9e2cac | 811 | case 0xca: |
0b0122fa MH |
812 | case 0xcb: |
813 | case 0xcf: | |
814 | case 0xea: /* jmp absolute -- ip is correct */ | |
815 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 816 | p->ainsn.boostable = 1; |
0b0122fa MH |
817 | goto no_change; |
818 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 819 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 820 | break; |
e7b5e11e | 821 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
822 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
823 | *tos = orig_ip + (*tos - copy_ip); | |
824 | goto no_change; | |
825 | #endif | |
1da177e4 | 826 | case 0xff: |
dc49e344 | 827 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
828 | /* |
829 | * call absolute, indirect | |
830 | * Fix return addr; ip is correct. | |
831 | * But this is not boostable | |
832 | */ | |
833 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 834 | goto no_change; |
8533bbe9 MH |
835 | } else if (((insn[1] & 0x31) == 0x20) || |
836 | ((insn[1] & 0x31) == 0x21)) { | |
837 | /* | |
838 | * jmp near and far, absolute indirect | |
839 | * ip is correct. And this is boostable | |
840 | */ | |
aa470140 | 841 | p->ainsn.boostable = 1; |
0b0122fa | 842 | goto no_change; |
1da177e4 | 843 | } |
1da177e4 LT |
844 | default: |
845 | break; | |
846 | } | |
847 | ||
aa470140 | 848 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
849 | if ((regs->ip > copy_ip) && |
850 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
851 | /* |
852 | * These instructions can be executed directly if it | |
853 | * jumps back to correct address. | |
854 | */ | |
c0f7ac3a MH |
855 | synthesize_reljump((void *)regs->ip, |
856 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
857 | p->ainsn.boostable = 1; |
858 | } else { | |
859 | p->ainsn.boostable = -1; | |
860 | } | |
861 | } | |
862 | ||
8533bbe9 | 863 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 864 | |
0b0122fa | 865 | no_change: |
1ecc798c | 866 | restore_btf(); |
1da177e4 LT |
867 | } |
868 | ||
8533bbe9 MH |
869 | /* |
870 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 871 | * remain disabled throughout this function. |
8533bbe9 MH |
872 | */ |
873 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 874 | { |
e7a510f9 AM |
875 | struct kprobe *cur = kprobe_running(); |
876 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
877 | ||
878 | if (!cur) | |
1da177e4 LT |
879 | return 0; |
880 | ||
acb5b8a2 YL |
881 | resume_execution(cur, regs, kcb); |
882 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 883 | |
e7a510f9 AM |
884 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
885 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
886 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 887 | } |
1da177e4 | 888 | |
8533bbe9 | 889 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
890 | if (kcb->kprobe_status == KPROBE_REENTER) { |
891 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 892 | goto out; |
aa3d7e3d | 893 | } |
e7a510f9 | 894 | reset_current_kprobe(); |
aa3d7e3d | 895 | out: |
1da177e4 LT |
896 | preempt_enable_no_resched(); |
897 | ||
898 | /* | |
65ea5b03 | 899 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
900 | * will have TF set, in which case, continue the remaining processing |
901 | * of do_debug, as if this is not a probe hit. | |
902 | */ | |
053de044 | 903 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
904 | return 0; |
905 | ||
906 | return 1; | |
907 | } | |
908 | ||
0f2fbdcb | 909 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 910 | { |
e7a510f9 AM |
911 | struct kprobe *cur = kprobe_running(); |
912 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
913 | ||
d6be29b8 | 914 | switch (kcb->kprobe_status) { |
c28f8966 PP |
915 | case KPROBE_HIT_SS: |
916 | case KPROBE_REENTER: | |
917 | /* | |
918 | * We are here because the instruction being single | |
919 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 920 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
921 | * and allow the page fault handler to continue as a |
922 | * normal page fault. | |
923 | */ | |
65ea5b03 | 924 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 925 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
926 | if (kcb->kprobe_status == KPROBE_REENTER) |
927 | restore_previous_kprobe(kcb); | |
928 | else | |
929 | reset_current_kprobe(); | |
1da177e4 | 930 | preempt_enable_no_resched(); |
c28f8966 PP |
931 | break; |
932 | case KPROBE_HIT_ACTIVE: | |
933 | case KPROBE_HIT_SSDONE: | |
934 | /* | |
935 | * We increment the nmissed count for accounting, | |
8533bbe9 | 936 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
937 | * these specific fault cases. |
938 | */ | |
939 | kprobes_inc_nmissed_count(cur); | |
940 | ||
941 | /* | |
942 | * We come here because instructions in the pre/post | |
943 | * handler caused the page_fault, this could happen | |
944 | * if handler tries to access user space by | |
945 | * copy_from_user(), get_user() etc. Let the | |
946 | * user-specified handler try to fix it first. | |
947 | */ | |
948 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
949 | return 1; | |
950 | ||
951 | /* | |
952 | * In case the user-specified fault handler returned | |
953 | * zero, try to fix up. | |
954 | */ | |
d6be29b8 MH |
955 | if (fixup_exception(regs)) |
956 | return 1; | |
6d48583b | 957 | |
c28f8966 | 958 | /* |
8533bbe9 | 959 | * fixup routine could not handle it, |
c28f8966 PP |
960 | * Let do_page_fault() fix it. |
961 | */ | |
962 | break; | |
963 | default: | |
964 | break; | |
1da177e4 LT |
965 | } |
966 | return 0; | |
967 | } | |
968 | ||
969 | /* | |
970 | * Wrapper routine for handling exceptions. | |
971 | */ | |
0f2fbdcb PP |
972 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
973 | unsigned long val, void *data) | |
1da177e4 | 974 | { |
ade1af77 | 975 | struct die_args *args = data; |
66ff2d06 AM |
976 | int ret = NOTIFY_DONE; |
977 | ||
8533bbe9 | 978 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 979 | return ret; |
980 | ||
1da177e4 LT |
981 | switch (val) { |
982 | case DIE_INT3: | |
983 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 984 | ret = NOTIFY_STOP; |
1da177e4 LT |
985 | break; |
986 | case DIE_DEBUG: | |
62edab90 P |
987 | if (post_kprobe_handler(args->regs)) { |
988 | /* | |
989 | * Reset the BS bit in dr6 (pointed by args->err) to | |
990 | * denote completion of processing | |
991 | */ | |
992 | (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; | |
66ff2d06 | 993 | ret = NOTIFY_STOP; |
62edab90 | 994 | } |
1da177e4 LT |
995 | break; |
996 | case DIE_GPF: | |
b506a9d0 QB |
997 | /* |
998 | * To be potentially processing a kprobe fault and to | |
999 | * trust the result from kprobe_running(), we have | |
1000 | * be non-preemptible. | |
1001 | */ | |
1002 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1003 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1004 | ret = NOTIFY_STOP; |
1da177e4 LT |
1005 | break; |
1006 | default: | |
1007 | break; | |
1008 | } | |
66ff2d06 | 1009 | return ret; |
1da177e4 LT |
1010 | } |
1011 | ||
0f2fbdcb | 1012 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1013 | { |
1014 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1015 | unsigned long addr; | |
e7a510f9 | 1016 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1017 | |
e7a510f9 | 1018 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1019 | kcb->jprobe_saved_sp = stack_addr(regs); |
1020 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1021 | ||
1da177e4 LT |
1022 | /* |
1023 | * As Linus pointed out, gcc assumes that the callee | |
1024 | * owns the argument space and could overwrite it, e.g. | |
1025 | * tailcall optimization. So, to be absolutely safe | |
1026 | * we also save and restore enough stack bytes to cover | |
1027 | * the argument area. | |
1028 | */ | |
e7a510f9 | 1029 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1030 | MIN_STACK_SIZE(addr)); |
053de044 | 1031 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1032 | trace_hardirqs_off(); |
65ea5b03 | 1033 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
1034 | return 1; |
1035 | } | |
1036 | ||
0f2fbdcb | 1037 | void __kprobes jprobe_return(void) |
1da177e4 | 1038 | { |
e7a510f9 AM |
1039 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1040 | ||
d6be29b8 MH |
1041 | asm volatile ( |
1042 | #ifdef CONFIG_X86_64 | |
1043 | " xchg %%rbx,%%rsp \n" | |
1044 | #else | |
1045 | " xchgl %%ebx,%%esp \n" | |
1046 | #endif | |
1047 | " int3 \n" | |
1048 | " .globl jprobe_return_end\n" | |
1049 | " jprobe_return_end: \n" | |
1050 | " nop \n"::"b" | |
1051 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1052 | } |
1053 | ||
0f2fbdcb | 1054 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1055 | { |
e7a510f9 | 1056 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1057 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1058 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1059 | ||
d6be29b8 MH |
1060 | if ((addr > (u8 *) jprobe_return) && |
1061 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1062 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1063 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1064 | printk(KERN_ERR |
1065 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1066 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1067 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1068 | show_registers(saved_regs); |
d6be29b8 | 1069 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1070 | show_registers(regs); |
1071 | BUG(); | |
1072 | } | |
e7a510f9 | 1073 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1074 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1075 | kcb->jprobes_stack, | |
1076 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1077 | preempt_enable_no_resched(); |
1da177e4 LT |
1078 | return 1; |
1079 | } | |
1080 | return 0; | |
1081 | } | |
ba8af12f | 1082 | |
c0f7ac3a MH |
1083 | |
1084 | #ifdef CONFIG_OPTPROBES | |
1085 | ||
1086 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ | |
1087 | static void __kprobes synthesize_relcall(void *from, void *to) | |
1088 | { | |
1089 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
1090 | } | |
1091 | ||
1092 | /* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */ | |
1093 | static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, | |
1094 | unsigned long val) | |
1095 | { | |
1096 | #ifdef CONFIG_X86_64 | |
1097 | *addr++ = 0x48; | |
1098 | *addr++ = 0xbf; | |
1099 | #else | |
1100 | *addr++ = 0xb8; | |
1101 | #endif | |
1102 | *(unsigned long *)addr = val; | |
1103 | } | |
1104 | ||
1105 | void __kprobes kprobes_optinsn_template_holder(void) | |
1106 | { | |
1107 | asm volatile ( | |
1108 | ".global optprobe_template_entry\n" | |
1109 | "optprobe_template_entry: \n" | |
1110 | #ifdef CONFIG_X86_64 | |
1111 | /* We don't bother saving the ss register */ | |
1112 | " pushq %rsp\n" | |
1113 | " pushfq\n" | |
1114 | SAVE_REGS_STRING | |
1115 | " movq %rsp, %rsi\n" | |
1116 | ".global optprobe_template_val\n" | |
1117 | "optprobe_template_val: \n" | |
1118 | ASM_NOP5 | |
1119 | ASM_NOP5 | |
1120 | ".global optprobe_template_call\n" | |
1121 | "optprobe_template_call: \n" | |
1122 | ASM_NOP5 | |
1123 | /* Move flags to rsp */ | |
1124 | " movq 144(%rsp), %rdx\n" | |
1125 | " movq %rdx, 152(%rsp)\n" | |
1126 | RESTORE_REGS_STRING | |
1127 | /* Skip flags entry */ | |
1128 | " addq $8, %rsp\n" | |
1129 | " popfq\n" | |
1130 | #else /* CONFIG_X86_32 */ | |
1131 | " pushf\n" | |
1132 | SAVE_REGS_STRING | |
1133 | " movl %esp, %edx\n" | |
1134 | ".global optprobe_template_val\n" | |
1135 | "optprobe_template_val: \n" | |
1136 | ASM_NOP5 | |
1137 | ".global optprobe_template_call\n" | |
1138 | "optprobe_template_call: \n" | |
1139 | ASM_NOP5 | |
1140 | RESTORE_REGS_STRING | |
1141 | " addl $4, %esp\n" /* skip cs */ | |
1142 | " popf\n" | |
1143 | #endif | |
1144 | ".global optprobe_template_end\n" | |
1145 | "optprobe_template_end: \n"); | |
1146 | } | |
1147 | ||
1148 | #define TMPL_MOVE_IDX \ | |
1149 | ((long)&optprobe_template_val - (long)&optprobe_template_entry) | |
1150 | #define TMPL_CALL_IDX \ | |
1151 | ((long)&optprobe_template_call - (long)&optprobe_template_entry) | |
1152 | #define TMPL_END_IDX \ | |
1153 | ((long)&optprobe_template_end - (long)&optprobe_template_entry) | |
1154 | ||
1155 | #define INT3_SIZE sizeof(kprobe_opcode_t) | |
1156 | ||
1157 | /* Optimized kprobe call back function: called from optinsn */ | |
1158 | static void __kprobes optimized_callback(struct optimized_kprobe *op, | |
1159 | struct pt_regs *regs) | |
1160 | { | |
1161 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
1162 | ||
1163 | preempt_disable(); | |
1164 | if (kprobe_running()) { | |
1165 | kprobes_inc_nmissed_count(&op->kp); | |
1166 | } else { | |
1167 | /* Save skipped registers */ | |
1168 | #ifdef CONFIG_X86_64 | |
1169 | regs->cs = __KERNEL_CS; | |
1170 | #else | |
1171 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
1172 | regs->gs = 0; | |
1173 | #endif | |
1174 | regs->ip = (unsigned long)op->kp.addr + INT3_SIZE; | |
1175 | regs->orig_ax = ~0UL; | |
1176 | ||
1177 | __get_cpu_var(current_kprobe) = &op->kp; | |
1178 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1179 | opt_pre_handler(&op->kp, regs); | |
1180 | __get_cpu_var(current_kprobe) = NULL; | |
1181 | } | |
1182 | preempt_enable_no_resched(); | |
1183 | } | |
1184 | ||
1185 | static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src) | |
1186 | { | |
1187 | int len = 0, ret; | |
1188 | ||
1189 | while (len < RELATIVEJUMP_SIZE) { | |
1190 | ret = __copy_instruction(dest + len, src + len, 1); | |
1191 | if (!ret || !can_boost(dest + len)) | |
1192 | return -EINVAL; | |
1193 | len += ret; | |
1194 | } | |
1195 | /* Check whether the address range is reserved */ | |
1196 | if (ftrace_text_reserved(src, src + len - 1) || | |
1197 | alternatives_text_reserved(src, src + len - 1)) | |
1198 | return -EBUSY; | |
1199 | ||
1200 | return len; | |
1201 | } | |
1202 | ||
1203 | /* Check whether insn is indirect jump */ | |
1204 | static int __kprobes insn_is_indirect_jump(struct insn *insn) | |
1205 | { | |
1206 | return ((insn->opcode.bytes[0] == 0xff && | |
1207 | (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */ | |
1208 | insn->opcode.bytes[0] == 0xea); /* Segment based jump */ | |
1209 | } | |
1210 | ||
1211 | /* Check whether insn jumps into specified address range */ | |
1212 | static int insn_jump_into_range(struct insn *insn, unsigned long start, int len) | |
1213 | { | |
1214 | unsigned long target = 0; | |
1215 | ||
1216 | switch (insn->opcode.bytes[0]) { | |
1217 | case 0xe0: /* loopne */ | |
1218 | case 0xe1: /* loope */ | |
1219 | case 0xe2: /* loop */ | |
1220 | case 0xe3: /* jcxz */ | |
1221 | case 0xe9: /* near relative jump */ | |
1222 | case 0xeb: /* short relative jump */ | |
1223 | break; | |
1224 | case 0x0f: | |
1225 | if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */ | |
1226 | break; | |
1227 | return 0; | |
1228 | default: | |
1229 | if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */ | |
1230 | break; | |
1231 | return 0; | |
1232 | } | |
1233 | target = (unsigned long)insn->next_byte + insn->immediate.value; | |
1234 | ||
1235 | return (start <= target && target <= start + len); | |
1236 | } | |
1237 | ||
1238 | /* Decode whole function to ensure any instructions don't jump into target */ | |
1239 | static int __kprobes can_optimize(unsigned long paddr) | |
1240 | { | |
1241 | int ret; | |
1242 | unsigned long addr, size = 0, offset = 0; | |
1243 | struct insn insn; | |
1244 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
1245 | /* Dummy buffers for lookup_symbol_attrs */ | |
1246 | static char __dummy_buf[KSYM_NAME_LEN]; | |
1247 | ||
1248 | /* Lookup symbol including addr */ | |
1249 | if (!kallsyms_lookup(paddr, &size, &offset, NULL, __dummy_buf)) | |
1250 | return 0; | |
1251 | ||
1252 | /* Check there is enough space for a relative jump. */ | |
1253 | if (size - offset < RELATIVEJUMP_SIZE) | |
1254 | return 0; | |
1255 | ||
1256 | /* Decode instructions */ | |
1257 | addr = paddr - offset; | |
1258 | while (addr < paddr - offset + size) { /* Decode until function end */ | |
1259 | if (search_exception_tables(addr)) | |
1260 | /* | |
1261 | * Since some fixup code will jumps into this function, | |
1262 | * we can't optimize kprobe in this function. | |
1263 | */ | |
1264 | return 0; | |
1265 | kernel_insn_init(&insn, (void *)addr); | |
1266 | insn_get_opcode(&insn); | |
1267 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
1268 | ret = recover_probed_instruction(buf, addr); | |
1269 | if (ret) | |
1270 | return 0; | |
1271 | kernel_insn_init(&insn, buf); | |
1272 | } | |
1273 | insn_get_length(&insn); | |
1274 | /* Recover address */ | |
1275 | insn.kaddr = (void *)addr; | |
1276 | insn.next_byte = (void *)(addr + insn.length); | |
1277 | /* Check any instructions don't jump into target */ | |
1278 | if (insn_is_indirect_jump(&insn) || | |
1279 | insn_jump_into_range(&insn, paddr + INT3_SIZE, | |
1280 | RELATIVE_ADDR_SIZE)) | |
1281 | return 0; | |
1282 | addr += insn.length; | |
1283 | } | |
1284 | ||
1285 | return 1; | |
1286 | } | |
1287 | ||
1288 | /* Check optimized_kprobe can actually be optimized. */ | |
1289 | int __kprobes arch_check_optimized_kprobe(struct optimized_kprobe *op) | |
1290 | { | |
1291 | int i; | |
1292 | struct kprobe *p; | |
1293 | ||
1294 | for (i = 1; i < op->optinsn.size; i++) { | |
1295 | p = get_kprobe(op->kp.addr + i); | |
1296 | if (p && !kprobe_disabled(p)) | |
1297 | return -EEXIST; | |
1298 | } | |
1299 | ||
1300 | return 0; | |
1301 | } | |
1302 | ||
1303 | /* Check the addr is within the optimized instructions. */ | |
1304 | int __kprobes arch_within_optimized_kprobe(struct optimized_kprobe *op, | |
1305 | unsigned long addr) | |
1306 | { | |
1307 | return ((unsigned long)op->kp.addr <= addr && | |
1308 | (unsigned long)op->kp.addr + op->optinsn.size > addr); | |
1309 | } | |
1310 | ||
1311 | /* Free optimized instruction slot */ | |
1312 | static __kprobes | |
1313 | void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty) | |
1314 | { | |
1315 | if (op->optinsn.insn) { | |
1316 | free_optinsn_slot(op->optinsn.insn, dirty); | |
1317 | op->optinsn.insn = NULL; | |
1318 | op->optinsn.size = 0; | |
1319 | } | |
1320 | } | |
1321 | ||
1322 | void __kprobes arch_remove_optimized_kprobe(struct optimized_kprobe *op) | |
1323 | { | |
1324 | __arch_remove_optimized_kprobe(op, 1); | |
1325 | } | |
1326 | ||
1327 | /* | |
1328 | * Copy replacing target instructions | |
1329 | * Target instructions MUST be relocatable (checked inside) | |
1330 | */ | |
1331 | int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op) | |
1332 | { | |
1333 | u8 *buf; | |
1334 | int ret; | |
1335 | long rel; | |
1336 | ||
1337 | if (!can_optimize((unsigned long)op->kp.addr)) | |
1338 | return -EILSEQ; | |
1339 | ||
1340 | op->optinsn.insn = get_optinsn_slot(); | |
1341 | if (!op->optinsn.insn) | |
1342 | return -ENOMEM; | |
1343 | ||
1344 | /* | |
1345 | * Verify if the address gap is in 2GB range, because this uses | |
1346 | * a relative jump. | |
1347 | */ | |
1348 | rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE; | |
1349 | if (abs(rel) > 0x7fffffff) | |
1350 | return -ERANGE; | |
1351 | ||
1352 | buf = (u8 *)op->optinsn.insn; | |
1353 | ||
1354 | /* Copy instructions into the out-of-line buffer */ | |
1355 | ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr); | |
1356 | if (ret < 0) { | |
1357 | __arch_remove_optimized_kprobe(op, 0); | |
1358 | return ret; | |
1359 | } | |
1360 | op->optinsn.size = ret; | |
1361 | ||
1362 | /* Copy arch-dep-instance from template */ | |
1363 | memcpy(buf, &optprobe_template_entry, TMPL_END_IDX); | |
1364 | ||
1365 | /* Set probe information */ | |
1366 | synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op); | |
1367 | ||
1368 | /* Set probe function call */ | |
1369 | synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback); | |
1370 | ||
1371 | /* Set returning jmp instruction at the tail of out-of-line buffer */ | |
1372 | synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size, | |
1373 | (u8 *)op->kp.addr + op->optinsn.size); | |
1374 | ||
1375 | flush_icache_range((unsigned long) buf, | |
1376 | (unsigned long) buf + TMPL_END_IDX + | |
1377 | op->optinsn.size + RELATIVEJUMP_SIZE); | |
1378 | return 0; | |
1379 | } | |
1380 | ||
1381 | /* Replace a breakpoint (int3) with a relative jump. */ | |
1382 | int __kprobes arch_optimize_kprobe(struct optimized_kprobe *op) | |
1383 | { | |
1384 | unsigned char jmp_code[RELATIVEJUMP_SIZE]; | |
1385 | s32 rel = (s32)((long)op->optinsn.insn - | |
1386 | ((long)op->kp.addr + RELATIVEJUMP_SIZE)); | |
1387 | ||
1388 | /* Backup instructions which will be replaced by jump address */ | |
1389 | memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE, | |
1390 | RELATIVE_ADDR_SIZE); | |
1391 | ||
1392 | jmp_code[0] = RELATIVEJUMP_OPCODE; | |
1393 | *(s32 *)(&jmp_code[1]) = rel; | |
1394 | ||
1395 | /* | |
1396 | * text_poke_smp doesn't support NMI/MCE code modifying. | |
1397 | * However, since kprobes itself also doesn't support NMI/MCE | |
1398 | * code probing, it's not a problem. | |
1399 | */ | |
1400 | text_poke_smp(op->kp.addr, jmp_code, RELATIVEJUMP_SIZE); | |
1401 | return 0; | |
1402 | } | |
1403 | ||
1404 | /* Replace a relative jump with a breakpoint (int3). */ | |
1405 | void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op) | |
1406 | { | |
1407 | u8 buf[RELATIVEJUMP_SIZE]; | |
1408 | ||
1409 | /* Set int3 to first byte for kprobes */ | |
1410 | buf[0] = BREAKPOINT_INSTRUCTION; | |
1411 | memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); | |
1412 | text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE); | |
1413 | } | |
1414 | ||
1415 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
1416 | struct pt_regs *regs, | |
1417 | int reenter) | |
1418 | { | |
1419 | struct optimized_kprobe *op; | |
1420 | ||
1421 | if (p->flags & KPROBE_FLAG_OPTIMIZED) { | |
1422 | /* This kprobe is really able to run optimized path. */ | |
1423 | op = container_of(p, struct optimized_kprobe, kp); | |
1424 | /* Detour through copied instructions */ | |
1425 | regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX; | |
1426 | if (!reenter) | |
1427 | reset_current_kprobe(); | |
1428 | preempt_enable_no_resched(); | |
1429 | return 1; | |
1430 | } | |
1431 | return 0; | |
1432 | } | |
1433 | #endif | |
1434 | ||
6772926b | 1435 | int __init arch_init_kprobes(void) |
ba8af12f | 1436 | { |
da07ab03 | 1437 | return 0; |
ba8af12f | 1438 | } |
bf8f6e5b AM |
1439 | |
1440 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1441 | { | |
bf8f6e5b AM |
1442 | return 0; |
1443 | } |