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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. | |
25 | * 2004-Oct Jim Keniston <kenistoj@us.ibm.com> and Prasanna S Panchamukhi | |
26 | * <prasanna@in.ibm.com> adapted for x86_64 | |
27 | * 2005-Mar Roland McGrath <roland@redhat.com> | |
28 | * Fixed to handle %rip-relative addressing mode correctly. | |
73649dab RL |
29 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> |
30 | * Added function return probes functionality | |
da07ab03 MH |
31 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster |
32 | * and kretprobe-booster for x86-64 | |
1da177e4 LT |
33 | */ |
34 | ||
1da177e4 LT |
35 | #include <linux/kprobes.h> |
36 | #include <linux/ptrace.h> | |
1da177e4 LT |
37 | #include <linux/string.h> |
38 | #include <linux/slab.h> | |
39 | #include <linux/preempt.h> | |
c28f8966 | 40 | #include <linux/module.h> |
1eeb66a1 | 41 | #include <linux/kdebug.h> |
9ec4b1f3 | 42 | |
1da177e4 | 43 | #include <asm/pgtable.h> |
c28f8966 | 44 | #include <asm/uaccess.h> |
19d36ccd | 45 | #include <asm/alternative.h> |
1da177e4 | 46 | |
1da177e4 | 47 | void jprobe_return_end(void); |
f709b122 | 48 | static void __kprobes arch_copy_kprobe(struct kprobe *p); |
1da177e4 | 49 | |
e7a510f9 AM |
50 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
51 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 52 | |
f438d914 MH |
53 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
54 | {"__switch_to", }, /* This function switches only current task, but | |
55 | doesn't switch kernel stack.*/ | |
56 | {NULL, NULL} /* Terminator */ | |
57 | }; | |
58 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
59 | ||
aa470140 MH |
60 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
61 | static __always_inline void set_jmp_op(void *from, void *to) | |
62 | { | |
63 | struct __arch_jmp_op { | |
64 | char op; | |
65 | s32 raddr; | |
66 | } __attribute__((packed)) * jop; | |
67 | jop = (struct __arch_jmp_op *)from; | |
68 | jop->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
69 | jop->op = RELATIVEJUMP_INSTRUCTION; | |
70 | } | |
71 | ||
72 | /* | |
73 | * returns non-zero if opcode is boostable | |
74 | * RIP relative instructions are adjusted at copying time | |
75 | */ | |
76 | static __always_inline int can_boost(kprobe_opcode_t *opcodes) | |
77 | { | |
78 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
79 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
80 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
81 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
82 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
83 | << (row % 64)) | |
84 | /* | |
85 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
86 | * Groups, and some special opcodes can not boost. | |
87 | */ | |
88 | static const unsigned long twobyte_is_boostable[256 / 64] = { | |
89 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
90 | /* ---------------------------------------------- */ | |
91 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0)|/* 00 */ | |
92 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)|/* 10 */ | |
93 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)|/* 20 */ | |
94 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0),/* 30 */ | |
95 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)|/* 40 */ | |
96 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)|/* 50 */ | |
97 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1)|/* 60 */ | |
98 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1),/* 70 */ | |
99 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)|/* 80 */ | |
100 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1)|/* 90 */ | |
101 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1)|/* a0 */ | |
102 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1),/* b0 */ | |
103 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1)|/* c0 */ | |
104 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1)|/* d0 */ | |
105 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1)|/* e0 */ | |
106 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
107 | /* ----------------------------------------------- */ | |
108 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
109 | }; | |
110 | #undef W | |
111 | kprobe_opcode_t opcode; | |
112 | kprobe_opcode_t *orig_opcodes = opcodes; | |
113 | ||
114 | retry: | |
115 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
116 | return 0; | |
117 | opcode = *(opcodes++); | |
118 | ||
119 | /* 2nd-byte opcode */ | |
120 | if (opcode == 0x0f) { | |
121 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
122 | return 0; | |
123 | return test_bit(*opcodes, twobyte_is_boostable); | |
124 | } | |
125 | ||
126 | switch (opcode & 0xf0) { | |
127 | case 0x40: | |
128 | goto retry; /* REX prefix is boostable */ | |
129 | case 0x60: | |
130 | if (0x63 < opcode && opcode < 0x67) | |
131 | goto retry; /* prefixes */ | |
132 | /* can't boost Address-size override and bound */ | |
133 | return (opcode != 0x62 && opcode != 0x67); | |
134 | case 0x70: | |
135 | return 0; /* can't boost conditional jump */ | |
136 | case 0xc0: | |
137 | /* can't boost software-interruptions */ | |
138 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
139 | case 0xd0: | |
140 | /* can boost AA* and XLAT */ | |
141 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
142 | case 0xe0: | |
143 | /* can boost in/out and absolute jmps */ | |
144 | return ((opcode & 0x04) || opcode == 0xea); | |
145 | case 0xf0: | |
146 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
147 | goto retry; /* lock/rep(ne) prefix */ | |
148 | /* clear and set flags are boostable */ | |
149 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
150 | default: | |
151 | /* segment override prefixes are boostable */ | |
152 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
153 | goto retry; /* prefixes */ | |
154 | /* CS override prefix and call are not boostable */ | |
155 | return (opcode != 0x2e && opcode != 0x9a); | |
156 | } | |
157 | } | |
158 | ||
1da177e4 LT |
159 | /* |
160 | * returns non-zero if opcode modifies the interrupt flag. | |
161 | */ | |
8645419c | 162 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
163 | { |
164 | switch (*insn) { | |
165 | case 0xfa: /* cli */ | |
166 | case 0xfb: /* sti */ | |
167 | case 0xcf: /* iret/iretd */ | |
168 | case 0x9d: /* popf/popfd */ | |
169 | return 1; | |
170 | } | |
171 | ||
172 | if (*insn >= 0x40 && *insn <= 0x4f && *++insn == 0xcf) | |
173 | return 1; | |
174 | return 0; | |
175 | } | |
176 | ||
0f2fbdcb | 177 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
1da177e4 LT |
178 | { |
179 | /* insn: must be on special executable page on x86_64. */ | |
2dd960d6 | 180 | p->ainsn.insn = get_insn_slot(); |
1da177e4 LT |
181 | if (!p->ainsn.insn) { |
182 | return -ENOMEM; | |
183 | } | |
49a2a1b8 | 184 | arch_copy_kprobe(p); |
1da177e4 LT |
185 | return 0; |
186 | } | |
187 | ||
188 | /* | |
189 | * Determine if the instruction uses the %rip-relative addressing mode. | |
aa470140 | 190 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 LT |
191 | * If not, return null. |
192 | */ | |
3b60211c | 193 | static s32 __kprobes *is_riprel(u8 *insn) |
1da177e4 LT |
194 | { |
195 | #define W(row,b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,ba,bb,bc,bd,be,bf) \ | |
196 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
197 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
198 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
199 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
200 | << (row % 64)) | |
201 | static const u64 onebyte_has_modrm[256 / 64] = { | |
202 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
203 | /* ------------------------------- */ | |
204 | W(0x00, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 00 */ | |
205 | W(0x10, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 10 */ | |
206 | W(0x20, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0)| /* 20 */ | |
207 | W(0x30, 1,1,1,1,0,0,0,0,1,1,1,1,0,0,0,0), /* 30 */ | |
208 | W(0x40, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 40 */ | |
209 | W(0x50, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 50 */ | |
210 | W(0x60, 0,0,1,1,0,0,0,0,0,1,0,1,0,0,0,0)| /* 60 */ | |
211 | W(0x70, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 70 */ | |
212 | W(0x80, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 80 */ | |
213 | W(0x90, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 90 */ | |
214 | W(0xa0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* a0 */ | |
215 | W(0xb0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* b0 */ | |
216 | W(0xc0, 1,1,0,0,1,1,1,1,0,0,0,0,0,0,0,0)| /* c0 */ | |
217 | W(0xd0, 1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,1)| /* d0 */ | |
218 | W(0xe0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* e0 */ | |
219 | W(0xf0, 0,0,0,0,0,0,1,1,0,0,0,0,0,0,1,1) /* f0 */ | |
220 | /* ------------------------------- */ | |
221 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
222 | }; | |
223 | static const u64 twobyte_has_modrm[256 / 64] = { | |
224 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
225 | /* ------------------------------- */ | |
226 | W(0x00, 1,1,1,1,0,0,0,0,0,0,0,0,0,1,0,1)| /* 0f */ | |
227 | W(0x10, 1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0)| /* 1f */ | |
228 | W(0x20, 1,1,1,1,1,0,1,0,1,1,1,1,1,1,1,1)| /* 2f */ | |
229 | W(0x30, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0), /* 3f */ | |
230 | W(0x40, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 4f */ | |
231 | W(0x50, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 5f */ | |
232 | W(0x60, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 6f */ | |
233 | W(0x70, 1,1,1,1,1,1,1,0,0,0,0,0,1,1,1,1), /* 7f */ | |
234 | W(0x80, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)| /* 8f */ | |
235 | W(0x90, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* 9f */ | |
236 | W(0xa0, 0,0,0,1,1,1,1,1,0,0,0,1,1,1,1,1)| /* af */ | |
237 | W(0xb0, 1,1,1,1,1,1,1,1,0,0,1,1,1,1,1,1), /* bf */ | |
238 | W(0xc0, 1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0)| /* cf */ | |
239 | W(0xd0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* df */ | |
240 | W(0xe0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)| /* ef */ | |
241 | W(0xf0, 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0) /* ff */ | |
242 | /* ------------------------------- */ | |
243 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
244 | }; | |
245 | #undef W | |
246 | int need_modrm; | |
247 | ||
248 | /* Skip legacy instruction prefixes. */ | |
249 | while (1) { | |
250 | switch (*insn) { | |
251 | case 0x66: | |
252 | case 0x67: | |
253 | case 0x2e: | |
254 | case 0x3e: | |
255 | case 0x26: | |
256 | case 0x64: | |
257 | case 0x65: | |
258 | case 0x36: | |
259 | case 0xf0: | |
260 | case 0xf3: | |
261 | case 0xf2: | |
262 | ++insn; | |
263 | continue; | |
264 | } | |
265 | break; | |
266 | } | |
267 | ||
268 | /* Skip REX instruction prefix. */ | |
269 | if ((*insn & 0xf0) == 0x40) | |
270 | ++insn; | |
271 | ||
272 | if (*insn == 0x0f) { /* Two-byte opcode. */ | |
273 | ++insn; | |
274 | need_modrm = test_bit(*insn, twobyte_has_modrm); | |
275 | } else { /* One-byte opcode. */ | |
276 | need_modrm = test_bit(*insn, onebyte_has_modrm); | |
277 | } | |
278 | ||
279 | if (need_modrm) { | |
280 | u8 modrm = *++insn; | |
281 | if ((modrm & 0xc7) == 0x05) { /* %rip+disp32 addressing mode */ | |
282 | /* Displacement follows ModRM byte. */ | |
283 | return (s32 *) ++insn; | |
284 | } | |
285 | } | |
286 | ||
287 | /* No %rip-relative addressing mode here. */ | |
288 | return NULL; | |
289 | } | |
290 | ||
f709b122 | 291 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 LT |
292 | { |
293 | s32 *ripdisp; | |
294 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE); | |
295 | ripdisp = is_riprel(p->ainsn.insn); | |
296 | if (ripdisp) { | |
297 | /* | |
298 | * The copied instruction uses the %rip-relative | |
299 | * addressing mode. Adjust the displacement for the | |
300 | * difference between the original location of this | |
301 | * instruction and the location of the copy that will | |
302 | * actually be run. The tricky bit here is making sure | |
303 | * that the sign extension happens correctly in this | |
304 | * calculation, since we need a signed 32-bit result to | |
305 | * be sign-extended to 64 bits when it's added to the | |
306 | * %rip value and yield the same 64-bit result that the | |
307 | * sign-extension of the original signed 32-bit | |
308 | * displacement would have given. | |
309 | */ | |
310 | s64 disp = (u8 *) p->addr + *ripdisp - (u8 *) p->ainsn.insn; | |
311 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ | |
312 | *ripdisp = disp; | |
313 | } | |
aa470140 MH |
314 | if (can_boost(p->addr)) { |
315 | p->ainsn.boostable = 0; | |
316 | } else { | |
317 | p->ainsn.boostable = -1; | |
318 | } | |
7e1048b1 | 319 | p->opcode = *p->addr; |
1da177e4 LT |
320 | } |
321 | ||
0f2fbdcb | 322 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 323 | { |
19d36ccd | 324 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
325 | } |
326 | ||
0f2fbdcb | 327 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 328 | { |
19d36ccd | 329 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
330 | } |
331 | ||
0498b635 | 332 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 333 | { |
7a7d1cf9 | 334 | mutex_lock(&kprobe_mutex); |
aa470140 | 335 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); |
7a7d1cf9 | 336 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
337 | } |
338 | ||
3b60211c | 339 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 340 | { |
e7a510f9 AM |
341 | kcb->prev_kprobe.kp = kprobe_running(); |
342 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
343 | kcb->prev_kprobe.old_rflags = kcb->kprobe_old_rflags; | |
344 | kcb->prev_kprobe.saved_rflags = kcb->kprobe_saved_rflags; | |
aa3d7e3d PP |
345 | } |
346 | ||
3b60211c | 347 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 348 | { |
e7a510f9 AM |
349 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
350 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
351 | kcb->kprobe_old_rflags = kcb->prev_kprobe.old_rflags; | |
352 | kcb->kprobe_saved_rflags = kcb->prev_kprobe.saved_rflags; | |
aa3d7e3d PP |
353 | } |
354 | ||
3b60211c | 355 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 356 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 357 | { |
e7a510f9 AM |
358 | __get_cpu_var(current_kprobe) = p; |
359 | kcb->kprobe_saved_rflags = kcb->kprobe_old_rflags | |
65ea5b03 | 360 | = (regs->flags & (TF_MASK | IF_MASK)); |
aa3d7e3d | 361 | if (is_IF_modifier(p->ainsn.insn)) |
e7a510f9 | 362 | kcb->kprobe_saved_rflags &= ~IF_MASK; |
aa3d7e3d PP |
363 | } |
364 | ||
1ecc798c RM |
365 | static __always_inline void clear_btf(void) |
366 | { | |
367 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
368 | wrmsrl(MSR_IA32_DEBUGCTLMSR, 0); | |
369 | } | |
370 | ||
371 | static __always_inline void restore_btf(void) | |
372 | { | |
373 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
374 | wrmsrl(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr); | |
375 | } | |
376 | ||
0f2fbdcb | 377 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 378 | { |
1ecc798c | 379 | clear_btf(); |
65ea5b03 PA |
380 | regs->flags |= TF_MASK; |
381 | regs->flags &= ~IF_MASK; | |
1da177e4 LT |
382 | /*single step inline if the instruction is an int3*/ |
383 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
65ea5b03 | 384 | regs->ip = (unsigned long)p->addr; |
1da177e4 | 385 | else |
65ea5b03 | 386 | regs->ip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
387 | } |
388 | ||
991a51d8 | 389 | /* Called with kretprobe_lock held */ |
4c4308cb | 390 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 391 | struct pt_regs *regs) |
73649dab | 392 | { |
65ea5b03 | 393 | unsigned long *sara = (unsigned long *)regs->sp; |
ba8af12f | 394 | |
4c4308cb CH |
395 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
396 | /* Replace the return addr with trampoline addr */ | |
397 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab RL |
398 | } |
399 | ||
0f2fbdcb | 400 | int __kprobes kprobe_handler(struct pt_regs *regs) |
1da177e4 LT |
401 | { |
402 | struct kprobe *p; | |
403 | int ret = 0; | |
65ea5b03 | 404 | kprobe_opcode_t *addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
405 | struct kprobe_ctlblk *kcb; |
406 | ||
407 | /* | |
408 | * We don't want to be preempted for the entire | |
409 | * duration of kprobe processing | |
410 | */ | |
411 | preempt_disable(); | |
412 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 413 | |
1da177e4 LT |
414 | /* Check we're not actually recursing */ |
415 | if (kprobe_running()) { | |
1da177e4 LT |
416 | p = get_kprobe(addr); |
417 | if (p) { | |
e7a510f9 | 418 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 419 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
65ea5b03 PA |
420 | regs->flags &= ~TF_MASK; |
421 | regs->flags |= kcb->kprobe_saved_rflags; | |
1da177e4 | 422 | goto no_kprobe; |
e7a510f9 | 423 | } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
aa3d7e3d PP |
424 | /* TODO: Provide re-entrancy from |
425 | * post_kprobes_handler() and avoid exception | |
426 | * stack corruption while single-stepping on | |
427 | * the instruction of the new probe. | |
428 | */ | |
429 | arch_disarm_kprobe(p); | |
65ea5b03 | 430 | regs->ip = (unsigned long)p->addr; |
e7a510f9 | 431 | reset_current_kprobe(); |
aa3d7e3d PP |
432 | ret = 1; |
433 | } else { | |
434 | /* We have reentered the kprobe_handler(), since | |
435 | * another probe was hit while within the | |
436 | * handler. We here save the original kprobe | |
437 | * variables and just single step on instruction | |
438 | * of the new probe without calling any user | |
439 | * handlers. | |
440 | */ | |
e7a510f9 AM |
441 | save_previous_kprobe(kcb); |
442 | set_current_kprobe(p, regs, kcb); | |
bf8d5c52 | 443 | kprobes_inc_nmissed_count(p); |
aa3d7e3d | 444 | prepare_singlestep(p, regs); |
e7a510f9 | 445 | kcb->kprobe_status = KPROBE_REENTER; |
aa3d7e3d | 446 | return 1; |
1da177e4 | 447 | } |
1da177e4 | 448 | } else { |
eb3a7292 KA |
449 | if (*addr != BREAKPOINT_INSTRUCTION) { |
450 | /* The breakpoint instruction was removed by | |
451 | * another cpu right after we hit, no further | |
452 | * handling of this interrupt is appropriate | |
453 | */ | |
65ea5b03 | 454 | regs->ip = (unsigned long)addr; |
eb3a7292 KA |
455 | ret = 1; |
456 | goto no_kprobe; | |
457 | } | |
e7a510f9 | 458 | p = __get_cpu_var(current_kprobe); |
1da177e4 LT |
459 | if (p->break_handler && p->break_handler(p, regs)) { |
460 | goto ss_probe; | |
461 | } | |
462 | } | |
1da177e4 LT |
463 | goto no_kprobe; |
464 | } | |
465 | ||
1da177e4 LT |
466 | p = get_kprobe(addr); |
467 | if (!p) { | |
1da177e4 LT |
468 | if (*addr != BREAKPOINT_INSTRUCTION) { |
469 | /* | |
470 | * The breakpoint instruction was removed right | |
471 | * after we hit it. Another cpu has removed | |
472 | * either a probepoint or a debugger breakpoint | |
473 | * at this address. In either case, no further | |
474 | * handling of this interrupt is appropriate. | |
bce06494 JK |
475 | * Back up over the (now missing) int3 and run |
476 | * the original instruction. | |
1da177e4 | 477 | */ |
65ea5b03 | 478 | regs->ip = (unsigned long)addr; |
1da177e4 LT |
479 | ret = 1; |
480 | } | |
481 | /* Not one of ours: let kernel handle it */ | |
482 | goto no_kprobe; | |
483 | } | |
484 | ||
e7a510f9 AM |
485 | set_current_kprobe(p, regs, kcb); |
486 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
487 | |
488 | if (p->pre_handler && p->pre_handler(p, regs)) | |
489 | /* handler has already set things up, so skip ss setup */ | |
490 | return 1; | |
491 | ||
492 | ss_probe: | |
aa470140 MH |
493 | #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) |
494 | if (p->ainsn.boostable == 1 && !p->post_handler) { | |
495 | /* Boost up -- we can execute copied instructions directly */ | |
496 | reset_current_kprobe(); | |
497 | regs->ip = (unsigned long)p->ainsn.insn; | |
498 | preempt_enable_no_resched(); | |
499 | return 1; | |
500 | } | |
501 | #endif | |
1da177e4 | 502 | prepare_singlestep(p, regs); |
e7a510f9 | 503 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
504 | return 1; |
505 | ||
506 | no_kprobe: | |
d217d545 | 507 | preempt_enable_no_resched(); |
1da177e4 LT |
508 | return ret; |
509 | } | |
510 | ||
73649dab | 511 | /* |
da07ab03 MH |
512 | * When a retprobed function returns, this code saves registers and |
513 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 514 | */ |
da07ab03 | 515 | void __kprobes kretprobe_trampoline_holder(void) |
73649dab RL |
516 | { |
517 | asm volatile ( ".global kretprobe_trampoline\n" | |
da07ab03 MH |
518 | "kretprobe_trampoline: \n" |
519 | /* We don't bother saving the ss register */ | |
520 | " pushq %rsp\n" | |
521 | " pushfq\n" | |
522 | /* | |
523 | * Skip cs, ip, orig_ax. | |
524 | * trampoline_handler() will plug in these values | |
525 | */ | |
526 | " subq $24, %rsp\n" | |
527 | " pushq %rdi\n" | |
528 | " pushq %rsi\n" | |
529 | " pushq %rdx\n" | |
530 | " pushq %rcx\n" | |
531 | " pushq %rax\n" | |
532 | " pushq %r8\n" | |
533 | " pushq %r9\n" | |
534 | " pushq %r10\n" | |
535 | " pushq %r11\n" | |
536 | " pushq %rbx\n" | |
537 | " pushq %rbp\n" | |
538 | " pushq %r12\n" | |
539 | " pushq %r13\n" | |
540 | " pushq %r14\n" | |
541 | " pushq %r15\n" | |
542 | " movq %rsp, %rdi\n" | |
543 | " call trampoline_handler\n" | |
544 | /* Replace saved sp with true return address. */ | |
545 | " movq %rax, 152(%rsp)\n" | |
546 | " popq %r15\n" | |
547 | " popq %r14\n" | |
548 | " popq %r13\n" | |
549 | " popq %r12\n" | |
550 | " popq %rbp\n" | |
551 | " popq %rbx\n" | |
552 | " popq %r11\n" | |
553 | " popq %r10\n" | |
554 | " popq %r9\n" | |
555 | " popq %r8\n" | |
556 | " popq %rax\n" | |
557 | " popq %rcx\n" | |
558 | " popq %rdx\n" | |
559 | " popq %rsi\n" | |
560 | " popq %rdi\n" | |
561 | /* Skip orig_ax, ip, cs */ | |
562 | " addq $24, %rsp\n" | |
563 | " popfq\n" | |
564 | " ret\n"); | |
73649dab RL |
565 | } |
566 | ||
567 | /* | |
da07ab03 | 568 | * Called from kretprobe_trampoline |
73649dab | 569 | */ |
da07ab03 | 570 | fastcall void * __kprobes trampoline_handler(struct pt_regs *regs) |
73649dab | 571 | { |
62c27be0 | 572 | struct kretprobe_instance *ri = NULL; |
99219a3f | 573 | struct hlist_head *head, empty_rp; |
62c27be0 | 574 | struct hlist_node *node, *tmp; |
991a51d8 | 575 | unsigned long flags, orig_ret_address = 0; |
ba8af12f | 576 | unsigned long trampoline_address =(unsigned long)&kretprobe_trampoline; |
73649dab | 577 | |
99219a3f | 578 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 579 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 580 | head = kretprobe_inst_table_head(current); |
da07ab03 MH |
581 | /* fixup rt_regs */ |
582 | regs->cs = __KERNEL_CS; | |
583 | regs->ip = trampoline_address; | |
584 | regs->orig_ax = 0xffffffffffffffff; | |
73649dab | 585 | |
ba8af12f RL |
586 | /* |
587 | * It is possible to have multiple instances associated with a given | |
588 | * task either because an multiple functions in the call path | |
589 | * have a return probe installed on them, and/or more then one return | |
590 | * return probe was registered for a target function. | |
591 | * | |
592 | * We can handle this because: | |
593 | * - instances are always inserted at the head of the list | |
594 | * - when multiple return probes are registered for the same | |
62c27be0 | 595 | * function, the first instance's ret_addr will point to the |
ba8af12f RL |
596 | * real return address, and all the rest will point to |
597 | * kretprobe_trampoline | |
598 | */ | |
599 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 600 | if (ri->task != current) |
ba8af12f | 601 | /* another task is sharing our hash bucket */ |
62c27be0 | 602 | continue; |
ba8af12f | 603 | |
da07ab03 MH |
604 | if (ri->rp && ri->rp->handler) { |
605 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
606 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 607 | ri->rp->handler(ri, regs); |
da07ab03 MH |
608 | __get_cpu_var(current_kprobe) = NULL; |
609 | } | |
ba8af12f RL |
610 | |
611 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 612 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
613 | |
614 | if (orig_ret_address != trampoline_address) | |
615 | /* | |
616 | * This is the real return address. Any other | |
617 | * instances associated with this task are for | |
618 | * other calls deeper on the call stack | |
619 | */ | |
620 | break; | |
73649dab | 621 | } |
ba8af12f | 622 | |
0f95b7fc | 623 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 624 | |
991a51d8 | 625 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
ba8af12f | 626 | |
99219a3f | 627 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
628 | hlist_del(&ri->hlist); | |
629 | kfree(ri); | |
630 | } | |
da07ab03 | 631 | return (void *)orig_ret_address; |
73649dab RL |
632 | } |
633 | ||
1da177e4 LT |
634 | /* |
635 | * Called after single-stepping. p->addr is the address of the | |
636 | * instruction whose first byte has been replaced by the "int 3" | |
637 | * instruction. To avoid the SMP problems that can occur when we | |
638 | * temporarily put back the original opcode to single-step, we | |
639 | * single-stepped a copy of the instruction. The address of this | |
640 | * copy is p->ainsn.insn. | |
641 | * | |
642 | * This function prepares to return from the post-single-step | |
643 | * interrupt. We have to fix up the stack as follows: | |
644 | * | |
645 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 646 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
647 | * it relative to the original instruction. |
648 | * | |
649 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 650 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
651 | * |
652 | * 2) If the single-stepped instruction was a call, the return address | |
653 | * that is atop the stack is the address following the copied instruction. | |
654 | * We need to make it the address following the original instruction. | |
aa470140 MH |
655 | * |
656 | * If this is the first time we've single-stepped the instruction at | |
657 | * this probepoint, and the instruction is boostable, boost it: add a | |
658 | * jump instruction after the copied instruction, that jumps to the next | |
659 | * instruction after the probepoint. | |
1da177e4 | 660 | */ |
e7a510f9 AM |
661 | static void __kprobes resume_execution(struct kprobe *p, |
662 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 663 | { |
65ea5b03 | 664 | unsigned long *tos = (unsigned long *)regs->sp; |
1da177e4 LT |
665 | unsigned long copy_rip = (unsigned long)p->ainsn.insn; |
666 | unsigned long orig_rip = (unsigned long)p->addr; | |
667 | kprobe_opcode_t *insn = p->ainsn.insn; | |
668 | ||
669 | /*skip the REX prefix*/ | |
670 | if (*insn >= 0x40 && *insn <= 0x4f) | |
671 | insn++; | |
672 | ||
65ea5b03 | 673 | regs->flags &= ~TF_MASK; |
1da177e4 | 674 | switch (*insn) { |
0b0122fa | 675 | case 0x9c: /* pushfl */ |
1da177e4 | 676 | *tos &= ~(TF_MASK | IF_MASK); |
e7a510f9 | 677 | *tos |= kcb->kprobe_old_rflags; |
1da177e4 | 678 | break; |
0b0122fa MH |
679 | case 0xc2: /* iret/ret/lret */ |
680 | case 0xc3: | |
0b9e2cac | 681 | case 0xca: |
0b0122fa MH |
682 | case 0xcb: |
683 | case 0xcf: | |
684 | case 0xea: /* jmp absolute -- ip is correct */ | |
685 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 686 | p->ainsn.boostable = 1; |
0b0122fa MH |
687 | goto no_change; |
688 | case 0xe8: /* call relative - Fix return addr */ | |
1da177e4 LT |
689 | *tos = orig_rip + (*tos - copy_rip); |
690 | break; | |
691 | case 0xff: | |
dc49e344 | 692 | if ((insn[1] & 0x30) == 0x10) { |
1da177e4 | 693 | /* call absolute, indirect */ |
0b0122fa | 694 | /* Fix return addr; ip is correct. */ |
aa470140 | 695 | /* not boostable */ |
1da177e4 | 696 | *tos = orig_rip + (*tos - copy_rip); |
0b0122fa | 697 | goto no_change; |
dc49e344 SO |
698 | } else if (((insn[1] & 0x31) == 0x20) || /* jmp near, absolute indirect */ |
699 | ((insn[1] & 0x31) == 0x21)) { /* jmp far, absolute indirect */ | |
aa470140 MH |
700 | /* ip is correct. And this is boostable */ |
701 | p->ainsn.boostable = 1; | |
0b0122fa | 702 | goto no_change; |
1da177e4 | 703 | } |
1da177e4 LT |
704 | default: |
705 | break; | |
706 | } | |
707 | ||
aa470140 MH |
708 | if (p->ainsn.boostable == 0) { |
709 | if ((regs->ip > copy_rip) && | |
710 | (regs->ip - copy_rip) + 5 < MAX_INSN_SIZE) { | |
711 | /* | |
712 | * These instructions can be executed directly if it | |
713 | * jumps back to correct address. | |
714 | */ | |
715 | set_jmp_op((void *)regs->ip, | |
716 | (void *)orig_rip + (regs->ip - copy_rip)); | |
717 | p->ainsn.boostable = 1; | |
718 | } else { | |
719 | p->ainsn.boostable = -1; | |
720 | } | |
721 | } | |
722 | ||
65ea5b03 PA |
723 | regs->ip = orig_rip + (regs->ip - copy_rip); |
724 | ||
0b0122fa | 725 | no_change: |
1ecc798c | 726 | restore_btf(); |
0b0122fa MH |
727 | |
728 | return; | |
1da177e4 LT |
729 | } |
730 | ||
0f2fbdcb | 731 | int __kprobes post_kprobe_handler(struct pt_regs *regs) |
1da177e4 | 732 | { |
e7a510f9 AM |
733 | struct kprobe *cur = kprobe_running(); |
734 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
735 | ||
736 | if (!cur) | |
1da177e4 LT |
737 | return 0; |
738 | ||
e7a510f9 AM |
739 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
740 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
741 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 742 | } |
1da177e4 | 743 | |
e7a510f9 | 744 | resume_execution(cur, regs, kcb); |
65ea5b03 PA |
745 | regs->flags |= kcb->kprobe_saved_rflags; |
746 | trace_hardirqs_fixup_flags(regs->flags); | |
1da177e4 | 747 | |
aa3d7e3d | 748 | /* Restore the original saved kprobes variables and continue. */ |
e7a510f9 AM |
749 | if (kcb->kprobe_status == KPROBE_REENTER) { |
750 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 751 | goto out; |
aa3d7e3d | 752 | } |
e7a510f9 | 753 | reset_current_kprobe(); |
aa3d7e3d | 754 | out: |
1da177e4 LT |
755 | preempt_enable_no_resched(); |
756 | ||
757 | /* | |
65ea5b03 | 758 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
759 | * will have TF set, in which case, continue the remaining processing |
760 | * of do_debug, as if this is not a probe hit. | |
761 | */ | |
65ea5b03 | 762 | if (regs->flags & TF_MASK) |
1da177e4 LT |
763 | return 0; |
764 | ||
765 | return 1; | |
766 | } | |
767 | ||
0f2fbdcb | 768 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 769 | { |
e7a510f9 AM |
770 | struct kprobe *cur = kprobe_running(); |
771 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
c28f8966 | 772 | const struct exception_table_entry *fixup; |
e7a510f9 | 773 | |
c28f8966 PP |
774 | switch(kcb->kprobe_status) { |
775 | case KPROBE_HIT_SS: | |
776 | case KPROBE_REENTER: | |
777 | /* | |
778 | * We are here because the instruction being single | |
779 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 780 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
781 | * and allow the page fault handler to continue as a |
782 | * normal page fault. | |
783 | */ | |
65ea5b03 PA |
784 | regs->ip = (unsigned long)cur->addr; |
785 | regs->flags |= kcb->kprobe_old_rflags; | |
c28f8966 PP |
786 | if (kcb->kprobe_status == KPROBE_REENTER) |
787 | restore_previous_kprobe(kcb); | |
788 | else | |
789 | reset_current_kprobe(); | |
1da177e4 | 790 | preempt_enable_no_resched(); |
c28f8966 PP |
791 | break; |
792 | case KPROBE_HIT_ACTIVE: | |
793 | case KPROBE_HIT_SSDONE: | |
794 | /* | |
795 | * We increment the nmissed count for accounting, | |
796 | * we can also use npre/npostfault count for accouting | |
797 | * these specific fault cases. | |
798 | */ | |
799 | kprobes_inc_nmissed_count(cur); | |
800 | ||
801 | /* | |
802 | * We come here because instructions in the pre/post | |
803 | * handler caused the page_fault, this could happen | |
804 | * if handler tries to access user space by | |
805 | * copy_from_user(), get_user() etc. Let the | |
806 | * user-specified handler try to fix it first. | |
807 | */ | |
808 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
809 | return 1; | |
810 | ||
811 | /* | |
812 | * In case the user-specified fault handler returned | |
813 | * zero, try to fix up. | |
814 | */ | |
65ea5b03 | 815 | fixup = search_exception_tables(regs->ip); |
c28f8966 | 816 | if (fixup) { |
65ea5b03 | 817 | regs->ip = fixup->fixup; |
c28f8966 PP |
818 | return 1; |
819 | } | |
820 | ||
821 | /* | |
822 | * fixup() could not handle it, | |
823 | * Let do_page_fault() fix it. | |
824 | */ | |
825 | break; | |
826 | default: | |
827 | break; | |
1da177e4 LT |
828 | } |
829 | return 0; | |
830 | } | |
831 | ||
832 | /* | |
833 | * Wrapper routine for handling exceptions. | |
834 | */ | |
0f2fbdcb PP |
835 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
836 | unsigned long val, void *data) | |
1da177e4 LT |
837 | { |
838 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
839 | int ret = NOTIFY_DONE; |
840 | ||
2326c770 | 841 | if (args->regs && user_mode(args->regs)) |
842 | return ret; | |
843 | ||
1da177e4 LT |
844 | switch (val) { |
845 | case DIE_INT3: | |
846 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 847 | ret = NOTIFY_STOP; |
1da177e4 LT |
848 | break; |
849 | case DIE_DEBUG: | |
850 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 851 | ret = NOTIFY_STOP; |
1da177e4 LT |
852 | break; |
853 | case DIE_GPF: | |
d217d545 AM |
854 | /* kprobe_running() needs smp_processor_id() */ |
855 | preempt_disable(); | |
1da177e4 LT |
856 | if (kprobe_running() && |
857 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 858 | ret = NOTIFY_STOP; |
d217d545 | 859 | preempt_enable(); |
1da177e4 LT |
860 | break; |
861 | default: | |
862 | break; | |
863 | } | |
66ff2d06 | 864 | return ret; |
1da177e4 LT |
865 | } |
866 | ||
0f2fbdcb | 867 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
868 | { |
869 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
870 | unsigned long addr; | |
e7a510f9 | 871 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 872 | |
e7a510f9 | 873 | kcb->jprobe_saved_regs = *regs; |
65ea5b03 | 874 | kcb->jprobe_saved_rsp = (long *) regs->sp; |
e7a510f9 | 875 | addr = (unsigned long)(kcb->jprobe_saved_rsp); |
1da177e4 LT |
876 | /* |
877 | * As Linus pointed out, gcc assumes that the callee | |
878 | * owns the argument space and could overwrite it, e.g. | |
879 | * tailcall optimization. So, to be absolutely safe | |
880 | * we also save and restore enough stack bytes to cover | |
881 | * the argument area. | |
882 | */ | |
e7a510f9 AM |
883 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
884 | MIN_STACK_SIZE(addr)); | |
65ea5b03 | 885 | regs->flags &= ~IF_MASK; |
58dfe883 | 886 | trace_hardirqs_off(); |
65ea5b03 | 887 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
888 | return 1; |
889 | } | |
890 | ||
0f2fbdcb | 891 | void __kprobes jprobe_return(void) |
1da177e4 | 892 | { |
e7a510f9 AM |
893 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
894 | ||
1da177e4 LT |
895 | asm volatile (" xchg %%rbx,%%rsp \n" |
896 | " int3 \n" | |
897 | " .globl jprobe_return_end \n" | |
898 | " jprobe_return_end: \n" | |
899 | " nop \n"::"b" | |
e7a510f9 | 900 | (kcb->jprobe_saved_rsp):"memory"); |
1da177e4 LT |
901 | } |
902 | ||
0f2fbdcb | 903 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 904 | { |
e7a510f9 | 905 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 906 | u8 *addr = (u8 *) (regs->ip - 1); |
e7a510f9 | 907 | unsigned long stack_addr = (unsigned long)(kcb->jprobe_saved_rsp); |
1da177e4 LT |
908 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
909 | ||
910 | if ((addr > (u8 *) jprobe_return) && (addr < (u8 *) jprobe_return_end)) { | |
65ea5b03 | 911 | if ((unsigned long *)regs->sp != kcb->jprobe_saved_rsp) { |
29b6cd79 | 912 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
65ea5b03 PA |
913 | printk("current sp %p does not match saved sp %p\n", |
914 | (long *)regs->sp, kcb->jprobe_saved_rsp); | |
1da177e4 LT |
915 | printk("Saved registers for jprobe %p\n", jp); |
916 | show_registers(saved_regs); | |
917 | printk("Current registers\n"); | |
918 | show_registers(regs); | |
919 | BUG(); | |
920 | } | |
e7a510f9 AM |
921 | *regs = kcb->jprobe_saved_regs; |
922 | memcpy((kprobe_opcode_t *) stack_addr, kcb->jprobes_stack, | |
1da177e4 | 923 | MIN_STACK_SIZE(stack_addr)); |
d217d545 | 924 | preempt_enable_no_resched(); |
1da177e4 LT |
925 | return 1; |
926 | } | |
927 | return 0; | |
928 | } | |
ba8af12f | 929 | |
6772926b | 930 | int __init arch_init_kprobes(void) |
ba8af12f | 931 | { |
da07ab03 | 932 | return 0; |
ba8af12f | 933 | } |
bf8f6e5b AM |
934 | |
935 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
936 | { | |
bf8f6e5b AM |
937 | return 0; |
938 | } |