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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. | |
315eb8a2 JS |
78 | * This is non-const to keep gcc from statically optimizing it out, as |
79 | * variable_test_bit makes gcc think only *(unsigned long*) is used. | |
8533bbe9 | 80 | */ |
315eb8a2 | 81 | static u32 twobyte_is_boostable[256 / 32] = { |
8533bbe9 MH |
82 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
83 | /* ---------------------------------------------- */ | |
84 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
85 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ | |
86 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ | |
87 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
88 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
89 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
90 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
91 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
92 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
93 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
94 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
95 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
96 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
97 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
98 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
99 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
100 | /* ----------------------------------------------- */ | |
101 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
102 | }; | |
8533bbe9 MH |
103 | #undef W |
104 | ||
f438d914 MH |
105 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
106 | {"__switch_to", }, /* This function switches only current task, but | |
107 | doesn't switch kernel stack.*/ | |
108 | {NULL, NULL} /* Terminator */ | |
109 | }; | |
110 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
111 | ||
c0f7ac3a | 112 | static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) |
aa470140 | 113 | { |
c0f7ac3a MH |
114 | struct __arch_relative_insn { |
115 | u8 op; | |
aa470140 | 116 | s32 raddr; |
c0f7ac3a MH |
117 | } __attribute__((packed)) *insn; |
118 | ||
119 | insn = (struct __arch_relative_insn *)from; | |
120 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
121 | insn->op = op; | |
122 | } | |
123 | ||
124 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
125 | static void __kprobes synthesize_reljump(void *from, void *to) | |
126 | { | |
127 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 MH |
128 | } |
129 | ||
9930927f | 130 | /* |
567a9fd8 | 131 | * Skip the prefixes of the instruction. |
9930927f | 132 | */ |
567a9fd8 | 133 | static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn) |
9930927f | 134 | { |
567a9fd8 MH |
135 | insn_attr_t attr; |
136 | ||
137 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
138 | while (inat_is_legacy_prefix(attr)) { | |
139 | insn++; | |
140 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
141 | } | |
9930927f | 142 | #ifdef CONFIG_X86_64 |
567a9fd8 MH |
143 | if (inat_is_rex_prefix(attr)) |
144 | insn++; | |
9930927f | 145 | #endif |
567a9fd8 | 146 | return insn; |
9930927f HH |
147 | } |
148 | ||
aa470140 | 149 | /* |
d6be29b8 MH |
150 | * Returns non-zero if opcode is boostable. |
151 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 152 | */ |
e7b5e11e | 153 | static int __kprobes can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 154 | { |
aa470140 MH |
155 | kprobe_opcode_t opcode; |
156 | kprobe_opcode_t *orig_opcodes = opcodes; | |
157 | ||
cde5edbd | 158 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
159 | return 0; /* Page fault may occur on this address. */ |
160 | ||
aa470140 MH |
161 | retry: |
162 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
163 | return 0; | |
164 | opcode = *(opcodes++); | |
165 | ||
166 | /* 2nd-byte opcode */ | |
167 | if (opcode == 0x0f) { | |
168 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
169 | return 0; | |
8533bbe9 MH |
170 | return test_bit(*opcodes, |
171 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
172 | } |
173 | ||
174 | switch (opcode & 0xf0) { | |
d6be29b8 | 175 | #ifdef CONFIG_X86_64 |
aa470140 MH |
176 | case 0x40: |
177 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 178 | #endif |
aa470140 MH |
179 | case 0x60: |
180 | if (0x63 < opcode && opcode < 0x67) | |
181 | goto retry; /* prefixes */ | |
182 | /* can't boost Address-size override and bound */ | |
183 | return (opcode != 0x62 && opcode != 0x67); | |
184 | case 0x70: | |
185 | return 0; /* can't boost conditional jump */ | |
186 | case 0xc0: | |
187 | /* can't boost software-interruptions */ | |
188 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
189 | case 0xd0: | |
190 | /* can boost AA* and XLAT */ | |
191 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
192 | case 0xe0: | |
193 | /* can boost in/out and absolute jmps */ | |
194 | return ((opcode & 0x04) || opcode == 0xea); | |
195 | case 0xf0: | |
196 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
197 | goto retry; /* lock/rep(ne) prefix */ | |
198 | /* clear and set flags are boostable */ | |
199 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
200 | default: | |
201 | /* segment override prefixes are boostable */ | |
202 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
203 | goto retry; /* prefixes */ | |
204 | /* CS override prefix and call are not boostable */ | |
205 | return (opcode != 0x2e && opcode != 0x9a); | |
206 | } | |
207 | } | |
208 | ||
b46b3d70 MH |
209 | /* Recover the probed instruction at addr for further analysis. */ |
210 | static int recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) | |
211 | { | |
212 | struct kprobe *kp; | |
213 | kp = get_kprobe((void *)addr); | |
214 | if (!kp) | |
215 | return -EINVAL; | |
216 | ||
217 | /* | |
218 | * Basically, kp->ainsn.insn has an original instruction. | |
219 | * However, RIP-relative instruction can not do single-stepping | |
c0f7ac3a | 220 | * at different place, __copy_instruction() tweaks the displacement of |
b46b3d70 MH |
221 | * that instruction. In that case, we can't recover the instruction |
222 | * from the kp->ainsn.insn. | |
223 | * | |
224 | * On the other hand, kp->opcode has a copy of the first byte of | |
225 | * the probed instruction, which is overwritten by int3. And | |
226 | * the instruction at kp->addr is not modified by kprobes except | |
227 | * for the first byte, we can recover the original instruction | |
228 | * from it and kp->opcode. | |
229 | */ | |
230 | memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
231 | buf[0] = kp->opcode; | |
232 | return 0; | |
233 | } | |
234 | ||
b46b3d70 MH |
235 | /* Check if paddr is at an instruction boundary */ |
236 | static int __kprobes can_probe(unsigned long paddr) | |
237 | { | |
238 | int ret; | |
239 | unsigned long addr, offset = 0; | |
240 | struct insn insn; | |
241 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
242 | ||
6abded71 | 243 | if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) |
b46b3d70 MH |
244 | return 0; |
245 | ||
246 | /* Decode instructions */ | |
247 | addr = paddr - offset; | |
248 | while (addr < paddr) { | |
249 | kernel_insn_init(&insn, (void *)addr); | |
250 | insn_get_opcode(&insn); | |
251 | ||
252 | /* | |
253 | * Check if the instruction has been modified by another | |
254 | * kprobe, in which case we replace the breakpoint by the | |
255 | * original instruction in our buffer. | |
256 | */ | |
257 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
258 | ret = recover_probed_instruction(buf, addr); | |
259 | if (ret) | |
260 | /* | |
261 | * Another debugging subsystem might insert | |
262 | * this breakpoint. In that case, we can't | |
263 | * recover it. | |
264 | */ | |
265 | return 0; | |
266 | kernel_insn_init(&insn, buf); | |
267 | } | |
268 | insn_get_length(&insn); | |
269 | addr += insn.length; | |
270 | } | |
271 | ||
272 | return (addr == paddr); | |
273 | } | |
274 | ||
1da177e4 | 275 | /* |
d6be29b8 | 276 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 277 | */ |
8645419c | 278 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 | 279 | { |
567a9fd8 MH |
280 | /* Skip prefixes */ |
281 | insn = skip_prefixes(insn); | |
282 | ||
1da177e4 LT |
283 | switch (*insn) { |
284 | case 0xfa: /* cli */ | |
285 | case 0xfb: /* sti */ | |
286 | case 0xcf: /* iret/iretd */ | |
287 | case 0x9d: /* popf/popfd */ | |
288 | return 1; | |
289 | } | |
9930927f | 290 | |
1da177e4 LT |
291 | return 0; |
292 | } | |
293 | ||
294 | /* | |
c0f7ac3a MH |
295 | * Copy an instruction and adjust the displacement if the instruction |
296 | * uses the %rip-relative addressing mode. | |
aa470140 | 297 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 298 | * If not, return null. |
31f80e45 | 299 | * Only applicable to 64-bit x86. |
1da177e4 | 300 | */ |
c0f7ac3a | 301 | static int __kprobes __copy_instruction(u8 *dest, u8 *src, int recover) |
1da177e4 | 302 | { |
89ae465b | 303 | struct insn insn; |
c0f7ac3a MH |
304 | int ret; |
305 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
1da177e4 | 306 | |
c0f7ac3a MH |
307 | kernel_insn_init(&insn, src); |
308 | if (recover) { | |
309 | insn_get_opcode(&insn); | |
310 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
311 | ret = recover_probed_instruction(buf, | |
312 | (unsigned long)src); | |
313 | if (ret) | |
314 | return 0; | |
315 | kernel_insn_init(&insn, buf); | |
316 | } | |
317 | } | |
318 | insn_get_length(&insn); | |
319 | memcpy(dest, insn.kaddr, insn.length); | |
320 | ||
321 | #ifdef CONFIG_X86_64 | |
89ae465b MH |
322 | if (insn_rip_relative(&insn)) { |
323 | s64 newdisp; | |
324 | u8 *disp; | |
c0f7ac3a | 325 | kernel_insn_init(&insn, dest); |
89ae465b MH |
326 | insn_get_displacement(&insn); |
327 | /* | |
328 | * The copied instruction uses the %rip-relative addressing | |
329 | * mode. Adjust the displacement for the difference between | |
330 | * the original location of this instruction and the location | |
331 | * of the copy that will actually be run. The tricky bit here | |
332 | * is making sure that the sign extension happens correctly in | |
333 | * this calculation, since we need a signed 32-bit result to | |
334 | * be sign-extended to 64 bits when it's added to the %rip | |
335 | * value and yield the same 64-bit result that the sign- | |
336 | * extension of the original signed 32-bit displacement would | |
337 | * have given. | |
338 | */ | |
c0f7ac3a MH |
339 | newdisp = (u8 *) src + (s64) insn.displacement.value - |
340 | (u8 *) dest; | |
89ae465b | 341 | BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */ |
c0f7ac3a | 342 | disp = (u8 *) dest + insn_offset_displacement(&insn); |
89ae465b | 343 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 344 | } |
d6be29b8 | 345 | #endif |
c0f7ac3a | 346 | return insn.length; |
31f80e45 | 347 | } |
1da177e4 | 348 | |
f709b122 | 349 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 350 | { |
c0f7ac3a MH |
351 | /* |
352 | * Copy an instruction without recovering int3, because it will be | |
353 | * put by another subsystem. | |
354 | */ | |
355 | __copy_instruction(p->ainsn.insn, p->addr, 0); | |
31f80e45 | 356 | |
8533bbe9 | 357 | if (can_boost(p->addr)) |
aa470140 | 358 | p->ainsn.boostable = 0; |
8533bbe9 | 359 | else |
aa470140 | 360 | p->ainsn.boostable = -1; |
8533bbe9 | 361 | |
7e1048b1 | 362 | p->opcode = *p->addr; |
1da177e4 LT |
363 | } |
364 | ||
8533bbe9 MH |
365 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
366 | { | |
4554dbcb MH |
367 | if (alternatives_text_reserved(p->addr, p->addr)) |
368 | return -EINVAL; | |
369 | ||
b46b3d70 MH |
370 | if (!can_probe((unsigned long)p->addr)) |
371 | return -EILSEQ; | |
8533bbe9 MH |
372 | /* insn: must be on special executable page on x86. */ |
373 | p->ainsn.insn = get_insn_slot(); | |
374 | if (!p->ainsn.insn) | |
375 | return -ENOMEM; | |
376 | arch_copy_kprobe(p); | |
377 | return 0; | |
378 | } | |
379 | ||
0f2fbdcb | 380 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 381 | { |
19d36ccd | 382 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
383 | } |
384 | ||
0f2fbdcb | 385 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 386 | { |
19d36ccd | 387 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
388 | } |
389 | ||
0498b635 | 390 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 391 | { |
12941560 MH |
392 | if (p->ainsn.insn) { |
393 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
394 | p->ainsn.insn = NULL; | |
395 | } | |
1da177e4 LT |
396 | } |
397 | ||
3b60211c | 398 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 399 | { |
e7a510f9 AM |
400 | kcb->prev_kprobe.kp = kprobe_running(); |
401 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
402 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
403 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
404 | } |
405 | ||
3b60211c | 406 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 407 | { |
b76834bc | 408 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
e7a510f9 | 409 | kcb->kprobe_status = kcb->prev_kprobe.status; |
8533bbe9 MH |
410 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
411 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
412 | } |
413 | ||
3b60211c | 414 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 415 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 416 | { |
b76834bc | 417 | __this_cpu_write(current_kprobe, p); |
8533bbe9 | 418 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 419 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
aa3d7e3d | 420 | if (is_IF_modifier(p->ainsn.insn)) |
053de044 | 421 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
422 | } |
423 | ||
e7b5e11e | 424 | static void __kprobes clear_btf(void) |
1ecc798c | 425 | { |
ea8e61b7 PZ |
426 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
427 | unsigned long debugctl = get_debugctlmsr(); | |
428 | ||
429 | debugctl &= ~DEBUGCTLMSR_BTF; | |
430 | update_debugctlmsr(debugctl); | |
431 | } | |
1ecc798c RM |
432 | } |
433 | ||
e7b5e11e | 434 | static void __kprobes restore_btf(void) |
1ecc798c | 435 | { |
ea8e61b7 PZ |
436 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
437 | unsigned long debugctl = get_debugctlmsr(); | |
438 | ||
439 | debugctl |= DEBUGCTLMSR_BTF; | |
440 | update_debugctlmsr(debugctl); | |
441 | } | |
1ecc798c RM |
442 | } |
443 | ||
4c4308cb | 444 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 445 | struct pt_regs *regs) |
73649dab | 446 | { |
8533bbe9 | 447 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 448 | |
4c4308cb | 449 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 450 | |
4c4308cb CH |
451 | /* Replace the return addr with trampoline addr */ |
452 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 453 | } |
f315decb | 454 | |
c0f7ac3a MH |
455 | #ifdef CONFIG_OPTPROBES |
456 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
457 | struct pt_regs *regs, | |
458 | int reenter); | |
459 | #else | |
460 | #define setup_detour_execution(p, regs, reenter) (0) | |
461 | #endif | |
462 | ||
f315decb | 463 | static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
0f94eb63 | 464 | struct kprobe_ctlblk *kcb, int reenter) |
f315decb | 465 | { |
c0f7ac3a MH |
466 | if (setup_detour_execution(p, regs, reenter)) |
467 | return; | |
468 | ||
615d0ebb | 469 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
470 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
471 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
472 | if (!reenter) |
473 | reset_current_kprobe(); | |
474 | /* | |
475 | * Reentering boosted probe doesn't reset current_kprobe, | |
476 | * nor set current_kprobe, because it doesn't use single | |
477 | * stepping. | |
478 | */ | |
f315decb AS |
479 | regs->ip = (unsigned long)p->ainsn.insn; |
480 | preempt_enable_no_resched(); | |
481 | return; | |
482 | } | |
483 | #endif | |
0f94eb63 MH |
484 | if (reenter) { |
485 | save_previous_kprobe(kcb); | |
486 | set_current_kprobe(p, regs, kcb); | |
487 | kcb->kprobe_status = KPROBE_REENTER; | |
488 | } else | |
489 | kcb->kprobe_status = KPROBE_HIT_SS; | |
490 | /* Prepare real single stepping */ | |
491 | clear_btf(); | |
492 | regs->flags |= X86_EFLAGS_TF; | |
493 | regs->flags &= ~X86_EFLAGS_IF; | |
494 | /* single step inline if the instruction is an int3 */ | |
495 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
496 | regs->ip = (unsigned long)p->addr; | |
497 | else | |
498 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb AS |
499 | } |
500 | ||
40102d4a HH |
501 | /* |
502 | * We have reentered the kprobe_handler(), since another probe was hit while | |
503 | * within the handler. We save the original kprobes variables and just single | |
504 | * step on the instruction of the new probe without calling any user handlers. | |
505 | */ | |
59e87cdc MH |
506 | static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
507 | struct kprobe_ctlblk *kcb) | |
40102d4a | 508 | { |
f315decb AS |
509 | switch (kcb->kprobe_status) { |
510 | case KPROBE_HIT_SSDONE: | |
f315decb | 511 | case KPROBE_HIT_ACTIVE: |
fb8830e7 | 512 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 513 | setup_singlestep(p, regs, kcb, 1); |
f315decb AS |
514 | break; |
515 | case KPROBE_HIT_SS: | |
e9afe9e1 MH |
516 | /* A probe has been hit in the codepath leading up to, or just |
517 | * after, single-stepping of a probed instruction. This entire | |
518 | * codepath should strictly reside in .kprobes.text section. | |
519 | * Raise a BUG or we'll continue in an endless reentering loop | |
520 | * and eventually a stack overflow. | |
521 | */ | |
522 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
523 | p->addr); | |
524 | dump_kprobe(p); | |
525 | BUG(); | |
f315decb AS |
526 | default: |
527 | /* impossible cases */ | |
528 | WARN_ON(1); | |
fb8830e7 | 529 | return 0; |
59e87cdc | 530 | } |
f315decb | 531 | |
59e87cdc | 532 | return 1; |
40102d4a | 533 | } |
73649dab | 534 | |
8533bbe9 MH |
535 | /* |
536 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 537 | * remain disabled throughout this function. |
8533bbe9 MH |
538 | */ |
539 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 540 | { |
8533bbe9 | 541 | kprobe_opcode_t *addr; |
f315decb | 542 | struct kprobe *p; |
d217d545 AM |
543 | struct kprobe_ctlblk *kcb; |
544 | ||
8533bbe9 | 545 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
546 | /* |
547 | * We don't want to be preempted for the entire | |
f315decb AS |
548 | * duration of kprobe processing. We conditionally |
549 | * re-enable preemption at the end of this function, | |
550 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
551 | */ |
552 | preempt_disable(); | |
1da177e4 | 553 | |
f315decb | 554 | kcb = get_kprobe_ctlblk(); |
b9760156 | 555 | p = get_kprobe(addr); |
f315decb | 556 | |
b9760156 | 557 | if (p) { |
b9760156 | 558 | if (kprobe_running()) { |
f315decb AS |
559 | if (reenter_kprobe(p, regs, kcb)) |
560 | return 1; | |
1da177e4 | 561 | } else { |
b9760156 HH |
562 | set_current_kprobe(p, regs, kcb); |
563 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 564 | |
1da177e4 | 565 | /* |
f315decb AS |
566 | * If we have no pre-handler or it returned 0, we |
567 | * continue with normal processing. If we have a | |
568 | * pre-handler and it returned non-zero, it prepped | |
569 | * for calling the break_handler below on re-entry | |
570 | * for jprobe processing, so get out doing nothing | |
571 | * more here. | |
1da177e4 | 572 | */ |
f315decb | 573 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 574 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 575 | return 1; |
b9760156 | 576 | } |
829e9245 MH |
577 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
578 | /* | |
579 | * The breakpoint instruction was removed right | |
580 | * after we hit it. Another cpu has removed | |
581 | * either a probepoint or a debugger breakpoint | |
582 | * at this address. In either case, no further | |
583 | * handling of this interrupt is appropriate. | |
584 | * Back up over the (now missing) int3 and run | |
585 | * the original instruction. | |
586 | */ | |
587 | regs->ip = (unsigned long)addr; | |
588 | preempt_enable_no_resched(); | |
589 | return 1; | |
f315decb | 590 | } else if (kprobe_running()) { |
b76834bc | 591 | p = __this_cpu_read(current_kprobe); |
f315decb | 592 | if (p->break_handler && p->break_handler(p, regs)) { |
0f94eb63 | 593 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 594 | return 1; |
1da177e4 | 595 | } |
f315decb | 596 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 597 | |
d217d545 | 598 | preempt_enable_no_resched(); |
f315decb | 599 | return 0; |
1da177e4 LT |
600 | } |
601 | ||
f007ea26 MH |
602 | #ifdef CONFIG_X86_64 |
603 | #define SAVE_REGS_STRING \ | |
604 | /* Skip cs, ip, orig_ax. */ \ | |
605 | " subq $24, %rsp\n" \ | |
606 | " pushq %rdi\n" \ | |
607 | " pushq %rsi\n" \ | |
608 | " pushq %rdx\n" \ | |
609 | " pushq %rcx\n" \ | |
610 | " pushq %rax\n" \ | |
611 | " pushq %r8\n" \ | |
612 | " pushq %r9\n" \ | |
613 | " pushq %r10\n" \ | |
614 | " pushq %r11\n" \ | |
615 | " pushq %rbx\n" \ | |
616 | " pushq %rbp\n" \ | |
617 | " pushq %r12\n" \ | |
618 | " pushq %r13\n" \ | |
619 | " pushq %r14\n" \ | |
620 | " pushq %r15\n" | |
621 | #define RESTORE_REGS_STRING \ | |
622 | " popq %r15\n" \ | |
623 | " popq %r14\n" \ | |
624 | " popq %r13\n" \ | |
625 | " popq %r12\n" \ | |
626 | " popq %rbp\n" \ | |
627 | " popq %rbx\n" \ | |
628 | " popq %r11\n" \ | |
629 | " popq %r10\n" \ | |
630 | " popq %r9\n" \ | |
631 | " popq %r8\n" \ | |
632 | " popq %rax\n" \ | |
633 | " popq %rcx\n" \ | |
634 | " popq %rdx\n" \ | |
635 | " popq %rsi\n" \ | |
636 | " popq %rdi\n" \ | |
637 | /* Skip orig_ax, ip, cs */ \ | |
638 | " addq $24, %rsp\n" | |
639 | #else | |
640 | #define SAVE_REGS_STRING \ | |
641 | /* Skip cs, ip, orig_ax and gs. */ \ | |
642 | " subl $16, %esp\n" \ | |
643 | " pushl %fs\n" \ | |
f007ea26 | 644 | " pushl %es\n" \ |
a1974798 | 645 | " pushl %ds\n" \ |
f007ea26 MH |
646 | " pushl %eax\n" \ |
647 | " pushl %ebp\n" \ | |
648 | " pushl %edi\n" \ | |
649 | " pushl %esi\n" \ | |
650 | " pushl %edx\n" \ | |
651 | " pushl %ecx\n" \ | |
652 | " pushl %ebx\n" | |
653 | #define RESTORE_REGS_STRING \ | |
654 | " popl %ebx\n" \ | |
655 | " popl %ecx\n" \ | |
656 | " popl %edx\n" \ | |
657 | " popl %esi\n" \ | |
658 | " popl %edi\n" \ | |
659 | " popl %ebp\n" \ | |
660 | " popl %eax\n" \ | |
661 | /* Skip ds, es, fs, gs, orig_ax, and ip. Note: don't pop cs here*/\ | |
662 | " addl $24, %esp\n" | |
663 | #endif | |
664 | ||
73649dab | 665 | /* |
da07ab03 MH |
666 | * When a retprobed function returns, this code saves registers and |
667 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 668 | */ |
f1452d42 | 669 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 670 | { |
d6be29b8 MH |
671 | asm volatile ( |
672 | ".global kretprobe_trampoline\n" | |
da07ab03 | 673 | "kretprobe_trampoline: \n" |
d6be29b8 | 674 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
675 | /* We don't bother saving the ss register */ |
676 | " pushq %rsp\n" | |
677 | " pushfq\n" | |
f007ea26 | 678 | SAVE_REGS_STRING |
da07ab03 MH |
679 | " movq %rsp, %rdi\n" |
680 | " call trampoline_handler\n" | |
681 | /* Replace saved sp with true return address. */ | |
682 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 683 | RESTORE_REGS_STRING |
da07ab03 | 684 | " popfq\n" |
d6be29b8 MH |
685 | #else |
686 | " pushf\n" | |
f007ea26 | 687 | SAVE_REGS_STRING |
d6be29b8 MH |
688 | " movl %esp, %eax\n" |
689 | " call trampoline_handler\n" | |
690 | /* Move flags to cs */ | |
fee039a1 MH |
691 | " movl 56(%esp), %edx\n" |
692 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 693 | /* Replace saved flags with true return address. */ |
fee039a1 | 694 | " movl %eax, 56(%esp)\n" |
f007ea26 | 695 | RESTORE_REGS_STRING |
d6be29b8 MH |
696 | " popf\n" |
697 | #endif | |
da07ab03 | 698 | " ret\n"); |
1017579a | 699 | } |
73649dab RL |
700 | |
701 | /* | |
da07ab03 | 702 | * Called from kretprobe_trampoline |
73649dab | 703 | */ |
f1452d42 | 704 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 705 | { |
62c27be0 | 706 | struct kretprobe_instance *ri = NULL; |
99219a3f | 707 | struct hlist_head *head, empty_rp; |
62c27be0 | 708 | struct hlist_node *node, *tmp; |
991a51d8 | 709 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 710 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
737480a0 | 711 | kprobe_opcode_t *correct_ret_addr = NULL; |
73649dab | 712 | |
99219a3f | 713 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 714 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 715 | /* fixup registers */ |
d6be29b8 | 716 | #ifdef CONFIG_X86_64 |
da07ab03 | 717 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
718 | #else |
719 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 720 | regs->gs = 0; |
d6be29b8 | 721 | #endif |
da07ab03 | 722 | regs->ip = trampoline_address; |
8533bbe9 | 723 | regs->orig_ax = ~0UL; |
73649dab | 724 | |
ba8af12f RL |
725 | /* |
726 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 727 | * task either because multiple functions in the call path have |
025dfdaf | 728 | * return probes installed on them, and/or more than one |
ba8af12f RL |
729 | * return probe was registered for a target function. |
730 | * | |
731 | * We can handle this because: | |
8533bbe9 | 732 | * - instances are always pushed into the head of the list |
ba8af12f | 733 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
734 | * function, the (chronologically) first instance's ret_addr |
735 | * will be the real return address, and all the rest will | |
736 | * point to kretprobe_trampoline. | |
ba8af12f RL |
737 | */ |
738 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 739 | if (ri->task != current) |
ba8af12f | 740 | /* another task is sharing our hash bucket */ |
62c27be0 | 741 | continue; |
ba8af12f | 742 | |
737480a0 KS |
743 | orig_ret_address = (unsigned long)ri->ret_addr; |
744 | ||
745 | if (orig_ret_address != trampoline_address) | |
746 | /* | |
747 | * This is the real return address. Any other | |
748 | * instances associated with this task are for | |
749 | * other calls deeper on the call stack | |
750 | */ | |
751 | break; | |
752 | } | |
753 | ||
754 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
755 | ||
756 | correct_ret_addr = ri->ret_addr; | |
757 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
758 | if (ri->task != current) | |
759 | /* another task is sharing our hash bucket */ | |
760 | continue; | |
761 | ||
762 | orig_ret_address = (unsigned long)ri->ret_addr; | |
da07ab03 | 763 | if (ri->rp && ri->rp->handler) { |
b76834bc | 764 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
da07ab03 | 765 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
737480a0 | 766 | ri->ret_addr = correct_ret_addr; |
ba8af12f | 767 | ri->rp->handler(ri, regs); |
b76834bc | 768 | __this_cpu_write(current_kprobe, NULL); |
da07ab03 | 769 | } |
ba8af12f | 770 | |
99219a3f | 771 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
772 | |
773 | if (orig_ret_address != trampoline_address) | |
774 | /* | |
775 | * This is the real return address. Any other | |
776 | * instances associated with this task are for | |
777 | * other calls deeper on the call stack | |
778 | */ | |
779 | break; | |
73649dab | 780 | } |
ba8af12f | 781 | |
ef53d9c5 | 782 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 783 | |
99219a3f | 784 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
785 | hlist_del(&ri->hlist); | |
786 | kfree(ri); | |
787 | } | |
da07ab03 | 788 | return (void *)orig_ret_address; |
73649dab RL |
789 | } |
790 | ||
1da177e4 LT |
791 | /* |
792 | * Called after single-stepping. p->addr is the address of the | |
793 | * instruction whose first byte has been replaced by the "int 3" | |
794 | * instruction. To avoid the SMP problems that can occur when we | |
795 | * temporarily put back the original opcode to single-step, we | |
796 | * single-stepped a copy of the instruction. The address of this | |
797 | * copy is p->ainsn.insn. | |
798 | * | |
799 | * This function prepares to return from the post-single-step | |
800 | * interrupt. We have to fix up the stack as follows: | |
801 | * | |
802 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 803 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
804 | * it relative to the original instruction. |
805 | * | |
806 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 807 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
808 | * |
809 | * 2) If the single-stepped instruction was a call, the return address | |
810 | * that is atop the stack is the address following the copied instruction. | |
811 | * We need to make it the address following the original instruction. | |
aa470140 MH |
812 | * |
813 | * If this is the first time we've single-stepped the instruction at | |
814 | * this probepoint, and the instruction is boostable, boost it: add a | |
815 | * jump instruction after the copied instruction, that jumps to the next | |
816 | * instruction after the probepoint. | |
1da177e4 | 817 | */ |
e7a510f9 AM |
818 | static void __kprobes resume_execution(struct kprobe *p, |
819 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 820 | { |
8533bbe9 MH |
821 | unsigned long *tos = stack_addr(regs); |
822 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
823 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
824 | kprobe_opcode_t *insn = p->ainsn.insn; |
825 | ||
567a9fd8 MH |
826 | /* Skip prefixes */ |
827 | insn = skip_prefixes(insn); | |
1da177e4 | 828 | |
053de044 | 829 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 830 | switch (*insn) { |
0b0122fa | 831 | case 0x9c: /* pushfl */ |
053de044 | 832 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 833 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 834 | break; |
0b0122fa MH |
835 | case 0xc2: /* iret/ret/lret */ |
836 | case 0xc3: | |
0b9e2cac | 837 | case 0xca: |
0b0122fa MH |
838 | case 0xcb: |
839 | case 0xcf: | |
840 | case 0xea: /* jmp absolute -- ip is correct */ | |
841 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 842 | p->ainsn.boostable = 1; |
0b0122fa MH |
843 | goto no_change; |
844 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 845 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 846 | break; |
e7b5e11e | 847 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
848 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
849 | *tos = orig_ip + (*tos - copy_ip); | |
850 | goto no_change; | |
851 | #endif | |
1da177e4 | 852 | case 0xff: |
dc49e344 | 853 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
854 | /* |
855 | * call absolute, indirect | |
856 | * Fix return addr; ip is correct. | |
857 | * But this is not boostable | |
858 | */ | |
859 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 860 | goto no_change; |
8533bbe9 MH |
861 | } else if (((insn[1] & 0x31) == 0x20) || |
862 | ((insn[1] & 0x31) == 0x21)) { | |
863 | /* | |
864 | * jmp near and far, absolute indirect | |
865 | * ip is correct. And this is boostable | |
866 | */ | |
aa470140 | 867 | p->ainsn.boostable = 1; |
0b0122fa | 868 | goto no_change; |
1da177e4 | 869 | } |
1da177e4 LT |
870 | default: |
871 | break; | |
872 | } | |
873 | ||
aa470140 | 874 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
875 | if ((regs->ip > copy_ip) && |
876 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
877 | /* |
878 | * These instructions can be executed directly if it | |
879 | * jumps back to correct address. | |
880 | */ | |
c0f7ac3a MH |
881 | synthesize_reljump((void *)regs->ip, |
882 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
883 | p->ainsn.boostable = 1; |
884 | } else { | |
885 | p->ainsn.boostable = -1; | |
886 | } | |
887 | } | |
888 | ||
8533bbe9 | 889 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 890 | |
0b0122fa | 891 | no_change: |
1ecc798c | 892 | restore_btf(); |
1da177e4 LT |
893 | } |
894 | ||
8533bbe9 MH |
895 | /* |
896 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 897 | * remain disabled throughout this function. |
8533bbe9 MH |
898 | */ |
899 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 900 | { |
e7a510f9 AM |
901 | struct kprobe *cur = kprobe_running(); |
902 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
903 | ||
904 | if (!cur) | |
1da177e4 LT |
905 | return 0; |
906 | ||
acb5b8a2 YL |
907 | resume_execution(cur, regs, kcb); |
908 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 909 | |
e7a510f9 AM |
910 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
911 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
912 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 913 | } |
1da177e4 | 914 | |
8533bbe9 | 915 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
916 | if (kcb->kprobe_status == KPROBE_REENTER) { |
917 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 918 | goto out; |
aa3d7e3d | 919 | } |
e7a510f9 | 920 | reset_current_kprobe(); |
aa3d7e3d | 921 | out: |
1da177e4 LT |
922 | preempt_enable_no_resched(); |
923 | ||
924 | /* | |
65ea5b03 | 925 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
926 | * will have TF set, in which case, continue the remaining processing |
927 | * of do_debug, as if this is not a probe hit. | |
928 | */ | |
053de044 | 929 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
930 | return 0; |
931 | ||
932 | return 1; | |
933 | } | |
934 | ||
0f2fbdcb | 935 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 936 | { |
e7a510f9 AM |
937 | struct kprobe *cur = kprobe_running(); |
938 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
939 | ||
d6be29b8 | 940 | switch (kcb->kprobe_status) { |
c28f8966 PP |
941 | case KPROBE_HIT_SS: |
942 | case KPROBE_REENTER: | |
943 | /* | |
944 | * We are here because the instruction being single | |
945 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 946 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
947 | * and allow the page fault handler to continue as a |
948 | * normal page fault. | |
949 | */ | |
65ea5b03 | 950 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 951 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
952 | if (kcb->kprobe_status == KPROBE_REENTER) |
953 | restore_previous_kprobe(kcb); | |
954 | else | |
955 | reset_current_kprobe(); | |
1da177e4 | 956 | preempt_enable_no_resched(); |
c28f8966 PP |
957 | break; |
958 | case KPROBE_HIT_ACTIVE: | |
959 | case KPROBE_HIT_SSDONE: | |
960 | /* | |
961 | * We increment the nmissed count for accounting, | |
8533bbe9 | 962 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
963 | * these specific fault cases. |
964 | */ | |
965 | kprobes_inc_nmissed_count(cur); | |
966 | ||
967 | /* | |
968 | * We come here because instructions in the pre/post | |
969 | * handler caused the page_fault, this could happen | |
970 | * if handler tries to access user space by | |
971 | * copy_from_user(), get_user() etc. Let the | |
972 | * user-specified handler try to fix it first. | |
973 | */ | |
974 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
975 | return 1; | |
976 | ||
977 | /* | |
978 | * In case the user-specified fault handler returned | |
979 | * zero, try to fix up. | |
980 | */ | |
d6be29b8 MH |
981 | if (fixup_exception(regs)) |
982 | return 1; | |
6d48583b | 983 | |
c28f8966 | 984 | /* |
8533bbe9 | 985 | * fixup routine could not handle it, |
c28f8966 PP |
986 | * Let do_page_fault() fix it. |
987 | */ | |
988 | break; | |
989 | default: | |
990 | break; | |
1da177e4 LT |
991 | } |
992 | return 0; | |
993 | } | |
994 | ||
995 | /* | |
996 | * Wrapper routine for handling exceptions. | |
997 | */ | |
0f2fbdcb PP |
998 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
999 | unsigned long val, void *data) | |
1da177e4 | 1000 | { |
ade1af77 | 1001 | struct die_args *args = data; |
66ff2d06 AM |
1002 | int ret = NOTIFY_DONE; |
1003 | ||
8533bbe9 | 1004 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 1005 | return ret; |
1006 | ||
1da177e4 LT |
1007 | switch (val) { |
1008 | case DIE_INT3: | |
1009 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 1010 | ret = NOTIFY_STOP; |
1da177e4 LT |
1011 | break; |
1012 | case DIE_DEBUG: | |
62edab90 P |
1013 | if (post_kprobe_handler(args->regs)) { |
1014 | /* | |
1015 | * Reset the BS bit in dr6 (pointed by args->err) to | |
1016 | * denote completion of processing | |
1017 | */ | |
1018 | (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; | |
66ff2d06 | 1019 | ret = NOTIFY_STOP; |
62edab90 | 1020 | } |
1da177e4 LT |
1021 | break; |
1022 | case DIE_GPF: | |
b506a9d0 QB |
1023 | /* |
1024 | * To be potentially processing a kprobe fault and to | |
1025 | * trust the result from kprobe_running(), we have | |
1026 | * be non-preemptible. | |
1027 | */ | |
1028 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1029 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1030 | ret = NOTIFY_STOP; |
1da177e4 LT |
1031 | break; |
1032 | default: | |
1033 | break; | |
1034 | } | |
66ff2d06 | 1035 | return ret; |
1da177e4 LT |
1036 | } |
1037 | ||
0f2fbdcb | 1038 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1039 | { |
1040 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1041 | unsigned long addr; | |
e7a510f9 | 1042 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1043 | |
e7a510f9 | 1044 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1045 | kcb->jprobe_saved_sp = stack_addr(regs); |
1046 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1047 | ||
1da177e4 LT |
1048 | /* |
1049 | * As Linus pointed out, gcc assumes that the callee | |
1050 | * owns the argument space and could overwrite it, e.g. | |
1051 | * tailcall optimization. So, to be absolutely safe | |
1052 | * we also save and restore enough stack bytes to cover | |
1053 | * the argument area. | |
1054 | */ | |
e7a510f9 | 1055 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1056 | MIN_STACK_SIZE(addr)); |
053de044 | 1057 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1058 | trace_hardirqs_off(); |
65ea5b03 | 1059 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
1060 | return 1; |
1061 | } | |
1062 | ||
0f2fbdcb | 1063 | void __kprobes jprobe_return(void) |
1da177e4 | 1064 | { |
e7a510f9 AM |
1065 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1066 | ||
d6be29b8 MH |
1067 | asm volatile ( |
1068 | #ifdef CONFIG_X86_64 | |
1069 | " xchg %%rbx,%%rsp \n" | |
1070 | #else | |
1071 | " xchgl %%ebx,%%esp \n" | |
1072 | #endif | |
1073 | " int3 \n" | |
1074 | " .globl jprobe_return_end\n" | |
1075 | " jprobe_return_end: \n" | |
1076 | " nop \n"::"b" | |
1077 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1078 | } |
1079 | ||
0f2fbdcb | 1080 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1081 | { |
e7a510f9 | 1082 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1083 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1084 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1085 | ||
d6be29b8 MH |
1086 | if ((addr > (u8 *) jprobe_return) && |
1087 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1088 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1089 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1090 | printk(KERN_ERR |
1091 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1092 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1093 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1094 | show_registers(saved_regs); |
d6be29b8 | 1095 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1096 | show_registers(regs); |
1097 | BUG(); | |
1098 | } | |
e7a510f9 | 1099 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1100 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1101 | kcb->jprobes_stack, | |
1102 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1103 | preempt_enable_no_resched(); |
1da177e4 LT |
1104 | return 1; |
1105 | } | |
1106 | return 0; | |
1107 | } | |
ba8af12f | 1108 | |
c0f7ac3a MH |
1109 | |
1110 | #ifdef CONFIG_OPTPROBES | |
1111 | ||
1112 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ | |
1113 | static void __kprobes synthesize_relcall(void *from, void *to) | |
1114 | { | |
1115 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
1116 | } | |
1117 | ||
1118 | /* Insert a move instruction which sets a pointer to eax/rdi (1st arg). */ | |
1119 | static void __kprobes synthesize_set_arg1(kprobe_opcode_t *addr, | |
1120 | unsigned long val) | |
1121 | { | |
1122 | #ifdef CONFIG_X86_64 | |
1123 | *addr++ = 0x48; | |
1124 | *addr++ = 0xbf; | |
1125 | #else | |
1126 | *addr++ = 0xb8; | |
1127 | #endif | |
1128 | *(unsigned long *)addr = val; | |
1129 | } | |
1130 | ||
6376b229 | 1131 | static void __used __kprobes kprobes_optinsn_template_holder(void) |
c0f7ac3a MH |
1132 | { |
1133 | asm volatile ( | |
1134 | ".global optprobe_template_entry\n" | |
1135 | "optprobe_template_entry: \n" | |
1136 | #ifdef CONFIG_X86_64 | |
1137 | /* We don't bother saving the ss register */ | |
1138 | " pushq %rsp\n" | |
1139 | " pushfq\n" | |
1140 | SAVE_REGS_STRING | |
1141 | " movq %rsp, %rsi\n" | |
1142 | ".global optprobe_template_val\n" | |
1143 | "optprobe_template_val: \n" | |
1144 | ASM_NOP5 | |
1145 | ASM_NOP5 | |
1146 | ".global optprobe_template_call\n" | |
1147 | "optprobe_template_call: \n" | |
1148 | ASM_NOP5 | |
1149 | /* Move flags to rsp */ | |
1150 | " movq 144(%rsp), %rdx\n" | |
1151 | " movq %rdx, 152(%rsp)\n" | |
1152 | RESTORE_REGS_STRING | |
1153 | /* Skip flags entry */ | |
1154 | " addq $8, %rsp\n" | |
1155 | " popfq\n" | |
1156 | #else /* CONFIG_X86_32 */ | |
1157 | " pushf\n" | |
1158 | SAVE_REGS_STRING | |
1159 | " movl %esp, %edx\n" | |
1160 | ".global optprobe_template_val\n" | |
1161 | "optprobe_template_val: \n" | |
1162 | ASM_NOP5 | |
1163 | ".global optprobe_template_call\n" | |
1164 | "optprobe_template_call: \n" | |
1165 | ASM_NOP5 | |
1166 | RESTORE_REGS_STRING | |
1167 | " addl $4, %esp\n" /* skip cs */ | |
1168 | " popf\n" | |
1169 | #endif | |
1170 | ".global optprobe_template_end\n" | |
1171 | "optprobe_template_end: \n"); | |
1172 | } | |
1173 | ||
1174 | #define TMPL_MOVE_IDX \ | |
1175 | ((long)&optprobe_template_val - (long)&optprobe_template_entry) | |
1176 | #define TMPL_CALL_IDX \ | |
1177 | ((long)&optprobe_template_call - (long)&optprobe_template_entry) | |
1178 | #define TMPL_END_IDX \ | |
1179 | ((long)&optprobe_template_end - (long)&optprobe_template_entry) | |
1180 | ||
1181 | #define INT3_SIZE sizeof(kprobe_opcode_t) | |
1182 | ||
1183 | /* Optimized kprobe call back function: called from optinsn */ | |
1184 | static void __kprobes optimized_callback(struct optimized_kprobe *op, | |
1185 | struct pt_regs *regs) | |
1186 | { | |
1187 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
9bbeacf5 | 1188 | unsigned long flags; |
c0f7ac3a | 1189 | |
6274de49 MH |
1190 | /* This is possible if op is under delayed unoptimizing */ |
1191 | if (kprobe_disabled(&op->kp)) | |
1192 | return; | |
1193 | ||
9bbeacf5 | 1194 | local_irq_save(flags); |
c0f7ac3a MH |
1195 | if (kprobe_running()) { |
1196 | kprobes_inc_nmissed_count(&op->kp); | |
1197 | } else { | |
1198 | /* Save skipped registers */ | |
1199 | #ifdef CONFIG_X86_64 | |
1200 | regs->cs = __KERNEL_CS; | |
1201 | #else | |
1202 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
1203 | regs->gs = 0; | |
1204 | #endif | |
1205 | regs->ip = (unsigned long)op->kp.addr + INT3_SIZE; | |
1206 | regs->orig_ax = ~0UL; | |
1207 | ||
b76834bc | 1208 | __this_cpu_write(current_kprobe, &op->kp); |
c0f7ac3a MH |
1209 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
1210 | opt_pre_handler(&op->kp, regs); | |
b76834bc | 1211 | __this_cpu_write(current_kprobe, NULL); |
c0f7ac3a | 1212 | } |
9bbeacf5 | 1213 | local_irq_restore(flags); |
c0f7ac3a MH |
1214 | } |
1215 | ||
1216 | static int __kprobes copy_optimized_instructions(u8 *dest, u8 *src) | |
1217 | { | |
1218 | int len = 0, ret; | |
1219 | ||
1220 | while (len < RELATIVEJUMP_SIZE) { | |
1221 | ret = __copy_instruction(dest + len, src + len, 1); | |
1222 | if (!ret || !can_boost(dest + len)) | |
1223 | return -EINVAL; | |
1224 | len += ret; | |
1225 | } | |
1226 | /* Check whether the address range is reserved */ | |
1227 | if (ftrace_text_reserved(src, src + len - 1) || | |
4c3ef6d7 JB |
1228 | alternatives_text_reserved(src, src + len - 1) || |
1229 | jump_label_text_reserved(src, src + len - 1)) | |
c0f7ac3a MH |
1230 | return -EBUSY; |
1231 | ||
1232 | return len; | |
1233 | } | |
1234 | ||
1235 | /* Check whether insn is indirect jump */ | |
1236 | static int __kprobes insn_is_indirect_jump(struct insn *insn) | |
1237 | { | |
1238 | return ((insn->opcode.bytes[0] == 0xff && | |
1239 | (X86_MODRM_REG(insn->modrm.value) & 6) == 4) || /* Jump */ | |
1240 | insn->opcode.bytes[0] == 0xea); /* Segment based jump */ | |
1241 | } | |
1242 | ||
1243 | /* Check whether insn jumps into specified address range */ | |
1244 | static int insn_jump_into_range(struct insn *insn, unsigned long start, int len) | |
1245 | { | |
1246 | unsigned long target = 0; | |
1247 | ||
1248 | switch (insn->opcode.bytes[0]) { | |
1249 | case 0xe0: /* loopne */ | |
1250 | case 0xe1: /* loope */ | |
1251 | case 0xe2: /* loop */ | |
1252 | case 0xe3: /* jcxz */ | |
1253 | case 0xe9: /* near relative jump */ | |
1254 | case 0xeb: /* short relative jump */ | |
1255 | break; | |
1256 | case 0x0f: | |
1257 | if ((insn->opcode.bytes[1] & 0xf0) == 0x80) /* jcc near */ | |
1258 | break; | |
1259 | return 0; | |
1260 | default: | |
1261 | if ((insn->opcode.bytes[0] & 0xf0) == 0x70) /* jcc short */ | |
1262 | break; | |
1263 | return 0; | |
1264 | } | |
1265 | target = (unsigned long)insn->next_byte + insn->immediate.value; | |
1266 | ||
1267 | return (start <= target && target <= start + len); | |
1268 | } | |
1269 | ||
1270 | /* Decode whole function to ensure any instructions don't jump into target */ | |
1271 | static int __kprobes can_optimize(unsigned long paddr) | |
1272 | { | |
1273 | int ret; | |
1274 | unsigned long addr, size = 0, offset = 0; | |
1275 | struct insn insn; | |
1276 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
c0f7ac3a MH |
1277 | |
1278 | /* Lookup symbol including addr */ | |
6abded71 | 1279 | if (!kallsyms_lookup_size_offset(paddr, &size, &offset)) |
c0f7ac3a MH |
1280 | return 0; |
1281 | ||
2a8247a2 JO |
1282 | /* |
1283 | * Do not optimize in the entry code due to the unstable | |
1284 | * stack handling. | |
1285 | */ | |
1286 | if ((paddr >= (unsigned long )__entry_text_start) && | |
1287 | (paddr < (unsigned long )__entry_text_end)) | |
1288 | return 0; | |
1289 | ||
c0f7ac3a MH |
1290 | /* Check there is enough space for a relative jump. */ |
1291 | if (size - offset < RELATIVEJUMP_SIZE) | |
1292 | return 0; | |
1293 | ||
1294 | /* Decode instructions */ | |
1295 | addr = paddr - offset; | |
1296 | while (addr < paddr - offset + size) { /* Decode until function end */ | |
1297 | if (search_exception_tables(addr)) | |
1298 | /* | |
1299 | * Since some fixup code will jumps into this function, | |
1300 | * we can't optimize kprobe in this function. | |
1301 | */ | |
1302 | return 0; | |
1303 | kernel_insn_init(&insn, (void *)addr); | |
1304 | insn_get_opcode(&insn); | |
1305 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) { | |
1306 | ret = recover_probed_instruction(buf, addr); | |
1307 | if (ret) | |
1308 | return 0; | |
1309 | kernel_insn_init(&insn, buf); | |
1310 | } | |
1311 | insn_get_length(&insn); | |
1312 | /* Recover address */ | |
1313 | insn.kaddr = (void *)addr; | |
1314 | insn.next_byte = (void *)(addr + insn.length); | |
1315 | /* Check any instructions don't jump into target */ | |
1316 | if (insn_is_indirect_jump(&insn) || | |
1317 | insn_jump_into_range(&insn, paddr + INT3_SIZE, | |
1318 | RELATIVE_ADDR_SIZE)) | |
1319 | return 0; | |
1320 | addr += insn.length; | |
1321 | } | |
1322 | ||
1323 | return 1; | |
1324 | } | |
1325 | ||
1326 | /* Check optimized_kprobe can actually be optimized. */ | |
1327 | int __kprobes arch_check_optimized_kprobe(struct optimized_kprobe *op) | |
1328 | { | |
1329 | int i; | |
1330 | struct kprobe *p; | |
1331 | ||
1332 | for (i = 1; i < op->optinsn.size; i++) { | |
1333 | p = get_kprobe(op->kp.addr + i); | |
1334 | if (p && !kprobe_disabled(p)) | |
1335 | return -EEXIST; | |
1336 | } | |
1337 | ||
1338 | return 0; | |
1339 | } | |
1340 | ||
1341 | /* Check the addr is within the optimized instructions. */ | |
1342 | int __kprobes arch_within_optimized_kprobe(struct optimized_kprobe *op, | |
1343 | unsigned long addr) | |
1344 | { | |
1345 | return ((unsigned long)op->kp.addr <= addr && | |
1346 | (unsigned long)op->kp.addr + op->optinsn.size > addr); | |
1347 | } | |
1348 | ||
1349 | /* Free optimized instruction slot */ | |
1350 | static __kprobes | |
1351 | void __arch_remove_optimized_kprobe(struct optimized_kprobe *op, int dirty) | |
1352 | { | |
1353 | if (op->optinsn.insn) { | |
1354 | free_optinsn_slot(op->optinsn.insn, dirty); | |
1355 | op->optinsn.insn = NULL; | |
1356 | op->optinsn.size = 0; | |
1357 | } | |
1358 | } | |
1359 | ||
1360 | void __kprobes arch_remove_optimized_kprobe(struct optimized_kprobe *op) | |
1361 | { | |
1362 | __arch_remove_optimized_kprobe(op, 1); | |
1363 | } | |
1364 | ||
1365 | /* | |
1366 | * Copy replacing target instructions | |
1367 | * Target instructions MUST be relocatable (checked inside) | |
1368 | */ | |
1369 | int __kprobes arch_prepare_optimized_kprobe(struct optimized_kprobe *op) | |
1370 | { | |
1371 | u8 *buf; | |
1372 | int ret; | |
1373 | long rel; | |
1374 | ||
1375 | if (!can_optimize((unsigned long)op->kp.addr)) | |
1376 | return -EILSEQ; | |
1377 | ||
1378 | op->optinsn.insn = get_optinsn_slot(); | |
1379 | if (!op->optinsn.insn) | |
1380 | return -ENOMEM; | |
1381 | ||
1382 | /* | |
1383 | * Verify if the address gap is in 2GB range, because this uses | |
1384 | * a relative jump. | |
1385 | */ | |
1386 | rel = (long)op->optinsn.insn - (long)op->kp.addr + RELATIVEJUMP_SIZE; | |
1387 | if (abs(rel) > 0x7fffffff) | |
1388 | return -ERANGE; | |
1389 | ||
1390 | buf = (u8 *)op->optinsn.insn; | |
1391 | ||
1392 | /* Copy instructions into the out-of-line buffer */ | |
1393 | ret = copy_optimized_instructions(buf + TMPL_END_IDX, op->kp.addr); | |
1394 | if (ret < 0) { | |
1395 | __arch_remove_optimized_kprobe(op, 0); | |
1396 | return ret; | |
1397 | } | |
1398 | op->optinsn.size = ret; | |
1399 | ||
1400 | /* Copy arch-dep-instance from template */ | |
1401 | memcpy(buf, &optprobe_template_entry, TMPL_END_IDX); | |
1402 | ||
1403 | /* Set probe information */ | |
1404 | synthesize_set_arg1(buf + TMPL_MOVE_IDX, (unsigned long)op); | |
1405 | ||
1406 | /* Set probe function call */ | |
1407 | synthesize_relcall(buf + TMPL_CALL_IDX, optimized_callback); | |
1408 | ||
1409 | /* Set returning jmp instruction at the tail of out-of-line buffer */ | |
1410 | synthesize_reljump(buf + TMPL_END_IDX + op->optinsn.size, | |
1411 | (u8 *)op->kp.addr + op->optinsn.size); | |
1412 | ||
1413 | flush_icache_range((unsigned long) buf, | |
1414 | (unsigned long) buf + TMPL_END_IDX + | |
1415 | op->optinsn.size + RELATIVEJUMP_SIZE); | |
1416 | return 0; | |
1417 | } | |
1418 | ||
cd7ebe22 MH |
1419 | #define MAX_OPTIMIZE_PROBES 256 |
1420 | static struct text_poke_param *jump_poke_params; | |
1421 | static struct jump_poke_buffer { | |
1422 | u8 buf[RELATIVEJUMP_SIZE]; | |
1423 | } *jump_poke_bufs; | |
1424 | ||
1425 | static void __kprobes setup_optimize_kprobe(struct text_poke_param *tprm, | |
1426 | u8 *insn_buf, | |
1427 | struct optimized_kprobe *op) | |
c0f7ac3a | 1428 | { |
c0f7ac3a MH |
1429 | s32 rel = (s32)((long)op->optinsn.insn - |
1430 | ((long)op->kp.addr + RELATIVEJUMP_SIZE)); | |
1431 | ||
1432 | /* Backup instructions which will be replaced by jump address */ | |
1433 | memcpy(op->optinsn.copied_insn, op->kp.addr + INT3_SIZE, | |
1434 | RELATIVE_ADDR_SIZE); | |
1435 | ||
cd7ebe22 MH |
1436 | insn_buf[0] = RELATIVEJUMP_OPCODE; |
1437 | *(s32 *)(&insn_buf[1]) = rel; | |
1438 | ||
1439 | tprm->addr = op->kp.addr; | |
1440 | tprm->opcode = insn_buf; | |
1441 | tprm->len = RELATIVEJUMP_SIZE; | |
1442 | } | |
1443 | ||
1444 | /* | |
1445 | * Replace breakpoints (int3) with relative jumps. | |
1446 | * Caller must call with locking kprobe_mutex and text_mutex. | |
1447 | */ | |
1448 | void __kprobes arch_optimize_kprobes(struct list_head *oplist) | |
1449 | { | |
1450 | struct optimized_kprobe *op, *tmp; | |
1451 | int c = 0; | |
1452 | ||
1453 | list_for_each_entry_safe(op, tmp, oplist, list) { | |
1454 | WARN_ON(kprobe_disabled(&op->kp)); | |
1455 | /* Setup param */ | |
1456 | setup_optimize_kprobe(&jump_poke_params[c], | |
1457 | jump_poke_bufs[c].buf, op); | |
1458 | list_del_init(&op->list); | |
1459 | if (++c >= MAX_OPTIMIZE_PROBES) | |
1460 | break; | |
1461 | } | |
c0f7ac3a MH |
1462 | |
1463 | /* | |
1464 | * text_poke_smp doesn't support NMI/MCE code modifying. | |
1465 | * However, since kprobes itself also doesn't support NMI/MCE | |
1466 | * code probing, it's not a problem. | |
1467 | */ | |
cd7ebe22 | 1468 | text_poke_smp_batch(jump_poke_params, c); |
c0f7ac3a MH |
1469 | } |
1470 | ||
f984ba4e MH |
1471 | static void __kprobes setup_unoptimize_kprobe(struct text_poke_param *tprm, |
1472 | u8 *insn_buf, | |
1473 | struct optimized_kprobe *op) | |
1474 | { | |
1475 | /* Set int3 to first byte for kprobes */ | |
1476 | insn_buf[0] = BREAKPOINT_INSTRUCTION; | |
1477 | memcpy(insn_buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); | |
1478 | ||
1479 | tprm->addr = op->kp.addr; | |
1480 | tprm->opcode = insn_buf; | |
1481 | tprm->len = RELATIVEJUMP_SIZE; | |
1482 | } | |
1483 | ||
1484 | /* | |
1485 | * Recover original instructions and breakpoints from relative jumps. | |
1486 | * Caller must call with locking kprobe_mutex. | |
1487 | */ | |
1488 | extern void arch_unoptimize_kprobes(struct list_head *oplist, | |
1489 | struct list_head *done_list) | |
1490 | { | |
1491 | struct optimized_kprobe *op, *tmp; | |
1492 | int c = 0; | |
1493 | ||
1494 | list_for_each_entry_safe(op, tmp, oplist, list) { | |
1495 | /* Setup param */ | |
1496 | setup_unoptimize_kprobe(&jump_poke_params[c], | |
1497 | jump_poke_bufs[c].buf, op); | |
1498 | list_move(&op->list, done_list); | |
1499 | if (++c >= MAX_OPTIMIZE_PROBES) | |
1500 | break; | |
1501 | } | |
1502 | ||
1503 | /* | |
1504 | * text_poke_smp doesn't support NMI/MCE code modifying. | |
1505 | * However, since kprobes itself also doesn't support NMI/MCE | |
1506 | * code probing, it's not a problem. | |
1507 | */ | |
1508 | text_poke_smp_batch(jump_poke_params, c); | |
1509 | } | |
1510 | ||
c0f7ac3a MH |
1511 | /* Replace a relative jump with a breakpoint (int3). */ |
1512 | void __kprobes arch_unoptimize_kprobe(struct optimized_kprobe *op) | |
1513 | { | |
1514 | u8 buf[RELATIVEJUMP_SIZE]; | |
1515 | ||
1516 | /* Set int3 to first byte for kprobes */ | |
1517 | buf[0] = BREAKPOINT_INSTRUCTION; | |
1518 | memcpy(buf + 1, op->optinsn.copied_insn, RELATIVE_ADDR_SIZE); | |
1519 | text_poke_smp(op->kp.addr, buf, RELATIVEJUMP_SIZE); | |
1520 | } | |
1521 | ||
1522 | static int __kprobes setup_detour_execution(struct kprobe *p, | |
1523 | struct pt_regs *regs, | |
1524 | int reenter) | |
1525 | { | |
1526 | struct optimized_kprobe *op; | |
1527 | ||
1528 | if (p->flags & KPROBE_FLAG_OPTIMIZED) { | |
1529 | /* This kprobe is really able to run optimized path. */ | |
1530 | op = container_of(p, struct optimized_kprobe, kp); | |
1531 | /* Detour through copied instructions */ | |
1532 | regs->ip = (unsigned long)op->optinsn.insn + TMPL_END_IDX; | |
1533 | if (!reenter) | |
1534 | reset_current_kprobe(); | |
1535 | preempt_enable_no_resched(); | |
1536 | return 1; | |
1537 | } | |
1538 | return 0; | |
1539 | } | |
cd7ebe22 MH |
1540 | |
1541 | static int __kprobes init_poke_params(void) | |
1542 | { | |
1543 | /* Allocate code buffer and parameter array */ | |
1544 | jump_poke_bufs = kmalloc(sizeof(struct jump_poke_buffer) * | |
1545 | MAX_OPTIMIZE_PROBES, GFP_KERNEL); | |
1546 | if (!jump_poke_bufs) | |
1547 | return -ENOMEM; | |
1548 | ||
1549 | jump_poke_params = kmalloc(sizeof(struct text_poke_param) * | |
1550 | MAX_OPTIMIZE_PROBES, GFP_KERNEL); | |
1551 | if (!jump_poke_params) { | |
1552 | kfree(jump_poke_bufs); | |
1553 | jump_poke_bufs = NULL; | |
1554 | return -ENOMEM; | |
1555 | } | |
1556 | ||
1557 | return 0; | |
1558 | } | |
1559 | #else /* !CONFIG_OPTPROBES */ | |
1560 | static int __kprobes init_poke_params(void) | |
1561 | { | |
1562 | return 0; | |
1563 | } | |
c0f7ac3a MH |
1564 | #endif |
1565 | ||
6772926b | 1566 | int __init arch_init_kprobes(void) |
ba8af12f | 1567 | { |
cd7ebe22 | 1568 | return init_poke_params(); |
ba8af12f | 1569 | } |
bf8f6e5b AM |
1570 | |
1571 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1572 | { | |
bf8f6e5b AM |
1573 | return 0; |
1574 | } |