Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Kernel Probes (KProbes) | |
1da177e4 LT |
3 | * |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2002, 2004 | |
19 | * | |
20 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel | |
21 | * Probes initial implementation ( includes contributions from | |
22 | * Rusty Russell). | |
23 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes | |
24 | * interface to access function arguments. | |
d6be29b8 MH |
25 | * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
26 | * <prasanna@in.ibm.com> adapted for x86_64 from i386. | |
1da177e4 LT |
27 | * 2005-Mar Roland McGrath <roland@redhat.com> |
28 | * Fixed to handle %rip-relative addressing mode correctly. | |
d6be29b8 MH |
29 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
30 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi | |
31 | * <prasanna@in.ibm.com> added function-return probes. | |
32 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> | |
33 | * Added function return probes functionality | |
34 | * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added | |
35 | * kprobe-booster and kretprobe-booster for i386. | |
da07ab03 MH |
36 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster |
37 | * and kretprobe-booster for x86-64 | |
d6be29b8 MH |
38 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven |
39 | * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> | |
40 | * unified x86 kprobes code. | |
1da177e4 LT |
41 | */ |
42 | ||
1da177e4 LT |
43 | #include <linux/kprobes.h> |
44 | #include <linux/ptrace.h> | |
1da177e4 LT |
45 | #include <linux/string.h> |
46 | #include <linux/slab.h> | |
b506a9d0 | 47 | #include <linux/hardirq.h> |
1da177e4 | 48 | #include <linux/preempt.h> |
c28f8966 | 49 | #include <linux/module.h> |
1eeb66a1 | 50 | #include <linux/kdebug.h> |
9ec4b1f3 | 51 | |
8533bbe9 MH |
52 | #include <asm/cacheflush.h> |
53 | #include <asm/desc.h> | |
1da177e4 | 54 | #include <asm/pgtable.h> |
c28f8966 | 55 | #include <asm/uaccess.h> |
19d36ccd | 56 | #include <asm/alternative.h> |
1da177e4 | 57 | |
1da177e4 LT |
58 | void jprobe_return_end(void); |
59 | ||
e7a510f9 AM |
60 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
61 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 62 | |
d6be29b8 | 63 | #ifdef CONFIG_X86_64 |
8533bbe9 | 64 | #define stack_addr(regs) ((unsigned long *)regs->sp) |
d6be29b8 MH |
65 | #else |
66 | /* | |
67 | * "®s->sp" looks wrong, but it's correct for x86_32. x86_32 CPUs | |
68 | * don't save the ss and esp registers if the CPU is already in kernel | |
69 | * mode when it traps. So for kprobes, regs->sp and regs->ss are not | |
70 | * the [nonexistent] saved stack pointer and ss register, but rather | |
71 | * the top 8 bytes of the pre-int3 stack. So ®s->sp happens to | |
72 | * point to the top of the pre-int3 stack. | |
73 | */ | |
74 | #define stack_addr(regs) ((unsigned long *)®s->sp) | |
75 | #endif | |
8533bbe9 MH |
76 | |
77 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
78 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
79 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
80 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
81 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
82 | << (row % 32)) | |
83 | /* | |
84 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
85 | * Groups, and some special opcodes can not boost. | |
86 | */ | |
87 | static const u32 twobyte_is_boostable[256 / 32] = { | |
88 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
89 | /* ---------------------------------------------- */ | |
90 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
91 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ | |
92 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ | |
93 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
94 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
95 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
96 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
97 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
98 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
99 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
100 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
101 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
102 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
103 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
104 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
105 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
106 | /* ----------------------------------------------- */ | |
107 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
108 | }; | |
109 | static const u32 onebyte_has_modrm[256 / 32] = { | |
110 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
111 | /* ----------------------------------------------- */ | |
112 | W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 00 */ | |
113 | W(0x10, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 10 */ | |
114 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 20 */ | |
115 | W(0x30, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 30 */ | |
116 | W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */ | |
117 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
118 | W(0x60, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0) | /* 60 */ | |
119 | W(0x70, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 70 */ | |
120 | W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ | |
121 | W(0x90, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 90 */ | |
122 | W(0xa0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* a0 */ | |
123 | W(0xb0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* b0 */ | |
124 | W(0xc0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* c0 */ | |
125 | W(0xd0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ | |
126 | W(0xe0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* e0 */ | |
127 | W(0xf0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) /* f0 */ | |
128 | /* ----------------------------------------------- */ | |
129 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
130 | }; | |
131 | static const u32 twobyte_has_modrm[256 / 32] = { | |
132 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
133 | /* ----------------------------------------------- */ | |
134 | W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1) | /* 0f */ | |
135 | W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0) , /* 1f */ | |
136 | W(0x20, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 2f */ | |
137 | W(0x30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 3f */ | |
138 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 4f */ | |
139 | W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 5f */ | |
140 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 6f */ | |
141 | W(0x70, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1) , /* 7f */ | |
142 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 8f */ | |
143 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 9f */ | |
144 | W(0xa0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) | /* af */ | |
145 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1) , /* bf */ | |
146 | W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* cf */ | |
147 | W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* df */ | |
148 | W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* ef */ | |
149 | W(0xf0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* ff */ | |
150 | /* ----------------------------------------------- */ | |
151 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
152 | }; | |
153 | #undef W | |
154 | ||
f438d914 MH |
155 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
156 | {"__switch_to", }, /* This function switches only current task, but | |
157 | doesn't switch kernel stack.*/ | |
158 | {NULL, NULL} /* Terminator */ | |
159 | }; | |
160 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
161 | ||
aa470140 | 162 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
e7b5e11e | 163 | static void __kprobes set_jmp_op(void *from, void *to) |
aa470140 MH |
164 | { |
165 | struct __arch_jmp_op { | |
166 | char op; | |
167 | s32 raddr; | |
168 | } __attribute__((packed)) * jop; | |
169 | jop = (struct __arch_jmp_op *)from; | |
170 | jop->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
171 | jop->op = RELATIVEJUMP_INSTRUCTION; | |
172 | } | |
173 | ||
9930927f HH |
174 | /* |
175 | * Check for the REX prefix which can only exist on X86_64 | |
176 | * X86_32 always returns 0 | |
177 | */ | |
178 | static int __kprobes is_REX_prefix(kprobe_opcode_t *insn) | |
179 | { | |
180 | #ifdef CONFIG_X86_64 | |
181 | if ((*insn & 0xf0) == 0x40) | |
182 | return 1; | |
183 | #endif | |
184 | return 0; | |
185 | } | |
186 | ||
aa470140 | 187 | /* |
d6be29b8 MH |
188 | * Returns non-zero if opcode is boostable. |
189 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 190 | */ |
e7b5e11e | 191 | static int __kprobes can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 192 | { |
aa470140 MH |
193 | kprobe_opcode_t opcode; |
194 | kprobe_opcode_t *orig_opcodes = opcodes; | |
195 | ||
196 | retry: | |
197 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
198 | return 0; | |
199 | opcode = *(opcodes++); | |
200 | ||
201 | /* 2nd-byte opcode */ | |
202 | if (opcode == 0x0f) { | |
203 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
204 | return 0; | |
8533bbe9 MH |
205 | return test_bit(*opcodes, |
206 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
207 | } |
208 | ||
209 | switch (opcode & 0xf0) { | |
d6be29b8 | 210 | #ifdef CONFIG_X86_64 |
aa470140 MH |
211 | case 0x40: |
212 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 213 | #endif |
aa470140 MH |
214 | case 0x60: |
215 | if (0x63 < opcode && opcode < 0x67) | |
216 | goto retry; /* prefixes */ | |
217 | /* can't boost Address-size override and bound */ | |
218 | return (opcode != 0x62 && opcode != 0x67); | |
219 | case 0x70: | |
220 | return 0; /* can't boost conditional jump */ | |
221 | case 0xc0: | |
222 | /* can't boost software-interruptions */ | |
223 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
224 | case 0xd0: | |
225 | /* can boost AA* and XLAT */ | |
226 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
227 | case 0xe0: | |
228 | /* can boost in/out and absolute jmps */ | |
229 | return ((opcode & 0x04) || opcode == 0xea); | |
230 | case 0xf0: | |
231 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
232 | goto retry; /* lock/rep(ne) prefix */ | |
233 | /* clear and set flags are boostable */ | |
234 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
235 | default: | |
236 | /* segment override prefixes are boostable */ | |
237 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
238 | goto retry; /* prefixes */ | |
239 | /* CS override prefix and call are not boostable */ | |
240 | return (opcode != 0x2e && opcode != 0x9a); | |
241 | } | |
242 | } | |
243 | ||
1da177e4 | 244 | /* |
d6be29b8 | 245 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 246 | */ |
8645419c | 247 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
248 | { |
249 | switch (*insn) { | |
250 | case 0xfa: /* cli */ | |
251 | case 0xfb: /* sti */ | |
252 | case 0xcf: /* iret/iretd */ | |
253 | case 0x9d: /* popf/popfd */ | |
254 | return 1; | |
255 | } | |
9930927f | 256 | |
8533bbe9 | 257 | /* |
9930927f | 258 | * on X86_64, 0x40-0x4f are REX prefixes so we need to look |
8533bbe9 MH |
259 | * at the next byte instead.. but of course not recurse infinitely |
260 | */ | |
9930927f | 261 | if (is_REX_prefix(insn)) |
8533bbe9 | 262 | return is_IF_modifier(++insn); |
9930927f | 263 | |
1da177e4 LT |
264 | return 0; |
265 | } | |
266 | ||
267 | /* | |
8533bbe9 MH |
268 | * Adjust the displacement if the instruction uses the %rip-relative |
269 | * addressing mode. | |
aa470140 | 270 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 271 | * If not, return null. |
31f80e45 | 272 | * Only applicable to 64-bit x86. |
1da177e4 | 273 | */ |
8533bbe9 | 274 | static void __kprobes fix_riprel(struct kprobe *p) |
1da177e4 | 275 | { |
31f80e45 | 276 | #ifdef CONFIG_X86_64 |
8533bbe9 MH |
277 | u8 *insn = p->ainsn.insn; |
278 | s64 disp; | |
1da177e4 LT |
279 | int need_modrm; |
280 | ||
281 | /* Skip legacy instruction prefixes. */ | |
282 | while (1) { | |
283 | switch (*insn) { | |
284 | case 0x66: | |
285 | case 0x67: | |
286 | case 0x2e: | |
287 | case 0x3e: | |
288 | case 0x26: | |
289 | case 0x64: | |
290 | case 0x65: | |
291 | case 0x36: | |
292 | case 0xf0: | |
293 | case 0xf3: | |
294 | case 0xf2: | |
295 | ++insn; | |
296 | continue; | |
297 | } | |
298 | break; | |
299 | } | |
300 | ||
301 | /* Skip REX instruction prefix. */ | |
9930927f | 302 | if (is_REX_prefix(insn)) |
1da177e4 LT |
303 | ++insn; |
304 | ||
d6be29b8 MH |
305 | if (*insn == 0x0f) { |
306 | /* Two-byte opcode. */ | |
1da177e4 | 307 | ++insn; |
8533bbe9 MH |
308 | need_modrm = test_bit(*insn, |
309 | (unsigned long *)twobyte_has_modrm); | |
d6be29b8 MH |
310 | } else |
311 | /* One-byte opcode. */ | |
8533bbe9 MH |
312 | need_modrm = test_bit(*insn, |
313 | (unsigned long *)onebyte_has_modrm); | |
1da177e4 LT |
314 | |
315 | if (need_modrm) { | |
316 | u8 modrm = *++insn; | |
d6be29b8 MH |
317 | if ((modrm & 0xc7) == 0x05) { |
318 | /* %rip+disp32 addressing mode */ | |
1da177e4 | 319 | /* Displacement follows ModRM byte. */ |
8533bbe9 MH |
320 | ++insn; |
321 | /* | |
322 | * The copied instruction uses the %rip-relative | |
323 | * addressing mode. Adjust the displacement for the | |
324 | * difference between the original location of this | |
325 | * instruction and the location of the copy that will | |
326 | * actually be run. The tricky bit here is making sure | |
327 | * that the sign extension happens correctly in this | |
328 | * calculation, since we need a signed 32-bit result to | |
329 | * be sign-extended to 64 bits when it's added to the | |
330 | * %rip value and yield the same 64-bit result that the | |
331 | * sign-extension of the original signed 32-bit | |
332 | * displacement would have given. | |
333 | */ | |
334 | disp = (u8 *) p->addr + *((s32 *) insn) - | |
335 | (u8 *) p->ainsn.insn; | |
336 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ | |
337 | *(s32 *)insn = (s32) disp; | |
1da177e4 LT |
338 | } |
339 | } | |
d6be29b8 | 340 | #endif |
31f80e45 | 341 | } |
1da177e4 | 342 | |
f709b122 | 343 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 344 | { |
8533bbe9 | 345 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
31f80e45 | 346 | |
8533bbe9 | 347 | fix_riprel(p); |
31f80e45 | 348 | |
8533bbe9 | 349 | if (can_boost(p->addr)) |
aa470140 | 350 | p->ainsn.boostable = 0; |
8533bbe9 | 351 | else |
aa470140 | 352 | p->ainsn.boostable = -1; |
8533bbe9 | 353 | |
7e1048b1 | 354 | p->opcode = *p->addr; |
1da177e4 LT |
355 | } |
356 | ||
8533bbe9 MH |
357 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
358 | { | |
359 | /* insn: must be on special executable page on x86. */ | |
360 | p->ainsn.insn = get_insn_slot(); | |
361 | if (!p->ainsn.insn) | |
362 | return -ENOMEM; | |
363 | arch_copy_kprobe(p); | |
364 | return 0; | |
365 | } | |
366 | ||
0f2fbdcb | 367 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 368 | { |
19d36ccd | 369 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
370 | } |
371 | ||
0f2fbdcb | 372 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 373 | { |
19d36ccd | 374 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
375 | } |
376 | ||
0498b635 | 377 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 378 | { |
7a7d1cf9 | 379 | mutex_lock(&kprobe_mutex); |
aa470140 | 380 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); |
7a7d1cf9 | 381 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
382 | } |
383 | ||
3b60211c | 384 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 385 | { |
e7a510f9 AM |
386 | kcb->prev_kprobe.kp = kprobe_running(); |
387 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
388 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
389 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
390 | } |
391 | ||
3b60211c | 392 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 393 | { |
e7a510f9 AM |
394 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
395 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
8533bbe9 MH |
396 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
397 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
398 | } |
399 | ||
3b60211c | 400 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 401 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 402 | { |
e7a510f9 | 403 | __get_cpu_var(current_kprobe) = p; |
8533bbe9 | 404 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 405 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
aa3d7e3d | 406 | if (is_IF_modifier(p->ainsn.insn)) |
053de044 | 407 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
408 | } |
409 | ||
e7b5e11e | 410 | static void __kprobes clear_btf(void) |
1ecc798c RM |
411 | { |
412 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 413 | update_debugctlmsr(0); |
1ecc798c RM |
414 | } |
415 | ||
e7b5e11e | 416 | static void __kprobes restore_btf(void) |
1ecc798c RM |
417 | { |
418 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
5b0e5084 | 419 | update_debugctlmsr(current->thread.debugctlmsr); |
1ecc798c RM |
420 | } |
421 | ||
0f2fbdcb | 422 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 423 | { |
1ecc798c | 424 | clear_btf(); |
053de044 GOC |
425 | regs->flags |= X86_EFLAGS_TF; |
426 | regs->flags &= ~X86_EFLAGS_IF; | |
e7b5e11e | 427 | /* single step inline if the instruction is an int3 */ |
1da177e4 | 428 | if (p->opcode == BREAKPOINT_INSTRUCTION) |
65ea5b03 | 429 | regs->ip = (unsigned long)p->addr; |
1da177e4 | 430 | else |
65ea5b03 | 431 | regs->ip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
432 | } |
433 | ||
991a51d8 | 434 | /* Called with kretprobe_lock held */ |
4c4308cb | 435 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 436 | struct pt_regs *regs) |
73649dab | 437 | { |
8533bbe9 | 438 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 439 | |
4c4308cb | 440 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 441 | |
4c4308cb CH |
442 | /* Replace the return addr with trampoline addr */ |
443 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 444 | } |
f315decb | 445 | |
f315decb AS |
446 | static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
447 | struct kprobe_ctlblk *kcb) | |
448 | { | |
449 | #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) | |
450 | if (p->ainsn.boostable == 1 && !p->post_handler) { | |
451 | /* Boost up -- we can execute copied instructions directly */ | |
452 | reset_current_kprobe(); | |
453 | regs->ip = (unsigned long)p->ainsn.insn; | |
454 | preempt_enable_no_resched(); | |
455 | return; | |
456 | } | |
457 | #endif | |
458 | prepare_singlestep(p, regs); | |
459 | kcb->kprobe_status = KPROBE_HIT_SS; | |
460 | } | |
461 | ||
40102d4a HH |
462 | /* |
463 | * We have reentered the kprobe_handler(), since another probe was hit while | |
464 | * within the handler. We save the original kprobes variables and just single | |
465 | * step on the instruction of the new probe without calling any user handlers. | |
466 | */ | |
59e87cdc MH |
467 | static int __kprobes reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
468 | struct kprobe_ctlblk *kcb) | |
40102d4a | 469 | { |
f315decb AS |
470 | switch (kcb->kprobe_status) { |
471 | case KPROBE_HIT_SSDONE: | |
59e87cdc | 472 | #ifdef CONFIG_X86_64 |
59e87cdc MH |
473 | /* TODO: Provide re-entrancy from post_kprobes_handler() and |
474 | * avoid exception stack corruption while single-stepping on | |
475 | * the instruction of the new probe. | |
476 | */ | |
477 | arch_disarm_kprobe(p); | |
478 | regs->ip = (unsigned long)p->addr; | |
479 | reset_current_kprobe(); | |
f315decb AS |
480 | preempt_enable_no_resched(); |
481 | break; | |
59e87cdc | 482 | #endif |
f315decb | 483 | case KPROBE_HIT_ACTIVE: |
fb8830e7 AS |
484 | save_previous_kprobe(kcb); |
485 | set_current_kprobe(p, regs, kcb); | |
486 | kprobes_inc_nmissed_count(p); | |
487 | prepare_singlestep(p, regs); | |
488 | kcb->kprobe_status = KPROBE_REENTER; | |
f315decb AS |
489 | break; |
490 | case KPROBE_HIT_SS: | |
fb8830e7 | 491 | if (p == kprobe_running()) { |
a5c15d41 | 492 | regs->flags &= ~X86_EFLAGS_TF; |
f315decb AS |
493 | regs->flags |= kcb->kprobe_saved_flags; |
494 | return 0; | |
495 | } else { | |
fb8830e7 AS |
496 | /* A probe has been hit in the codepath leading up |
497 | * to, or just after, single-stepping of a probed | |
498 | * instruction. This entire codepath should strictly | |
499 | * reside in .kprobes.text section. Raise a warning | |
500 | * to highlight this peculiar case. | |
501 | */ | |
f315decb | 502 | } |
f315decb AS |
503 | default: |
504 | /* impossible cases */ | |
505 | WARN_ON(1); | |
fb8830e7 | 506 | return 0; |
59e87cdc | 507 | } |
f315decb | 508 | |
59e87cdc | 509 | return 1; |
40102d4a | 510 | } |
73649dab | 511 | |
8533bbe9 MH |
512 | /* |
513 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
514 | * remain disabled thorough out this function. | |
515 | */ | |
516 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 517 | { |
8533bbe9 | 518 | kprobe_opcode_t *addr; |
f315decb | 519 | struct kprobe *p; |
d217d545 AM |
520 | struct kprobe_ctlblk *kcb; |
521 | ||
8533bbe9 | 522 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
f315decb AS |
523 | if (*addr != BREAKPOINT_INSTRUCTION) { |
524 | /* | |
525 | * The breakpoint instruction was removed right | |
526 | * after we hit it. Another cpu has removed | |
527 | * either a probepoint or a debugger breakpoint | |
528 | * at this address. In either case, no further | |
529 | * handling of this interrupt is appropriate. | |
530 | * Back up over the (now missing) int3 and run | |
531 | * the original instruction. | |
532 | */ | |
533 | regs->ip = (unsigned long)addr; | |
534 | return 1; | |
535 | } | |
8533bbe9 | 536 | |
d217d545 AM |
537 | /* |
538 | * We don't want to be preempted for the entire | |
f315decb AS |
539 | * duration of kprobe processing. We conditionally |
540 | * re-enable preemption at the end of this function, | |
541 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
542 | */ |
543 | preempt_disable(); | |
1da177e4 | 544 | |
f315decb | 545 | kcb = get_kprobe_ctlblk(); |
b9760156 | 546 | p = get_kprobe(addr); |
f315decb | 547 | |
b9760156 | 548 | if (p) { |
b9760156 | 549 | if (kprobe_running()) { |
f315decb AS |
550 | if (reenter_kprobe(p, regs, kcb)) |
551 | return 1; | |
1da177e4 | 552 | } else { |
b9760156 HH |
553 | set_current_kprobe(p, regs, kcb); |
554 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 555 | |
1da177e4 | 556 | /* |
f315decb AS |
557 | * If we have no pre-handler or it returned 0, we |
558 | * continue with normal processing. If we have a | |
559 | * pre-handler and it returned non-zero, it prepped | |
560 | * for calling the break_handler below on re-entry | |
561 | * for jprobe processing, so get out doing nothing | |
562 | * more here. | |
1da177e4 | 563 | */ |
f315decb AS |
564 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
565 | setup_singlestep(p, regs, kcb); | |
566 | return 1; | |
b9760156 | 567 | } |
f315decb AS |
568 | } else if (kprobe_running()) { |
569 | p = __get_cpu_var(current_kprobe); | |
570 | if (p->break_handler && p->break_handler(p, regs)) { | |
571 | setup_singlestep(p, regs, kcb); | |
572 | return 1; | |
1da177e4 | 573 | } |
f315decb | 574 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 575 | |
d217d545 | 576 | preempt_enable_no_resched(); |
f315decb | 577 | return 0; |
1da177e4 LT |
578 | } |
579 | ||
73649dab | 580 | /* |
da07ab03 MH |
581 | * When a retprobed function returns, this code saves registers and |
582 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 583 | */ |
f1452d42 | 584 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 585 | { |
d6be29b8 MH |
586 | asm volatile ( |
587 | ".global kretprobe_trampoline\n" | |
da07ab03 | 588 | "kretprobe_trampoline: \n" |
d6be29b8 | 589 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
590 | /* We don't bother saving the ss register */ |
591 | " pushq %rsp\n" | |
592 | " pushfq\n" | |
593 | /* | |
594 | * Skip cs, ip, orig_ax. | |
595 | * trampoline_handler() will plug in these values | |
596 | */ | |
597 | " subq $24, %rsp\n" | |
598 | " pushq %rdi\n" | |
599 | " pushq %rsi\n" | |
600 | " pushq %rdx\n" | |
601 | " pushq %rcx\n" | |
602 | " pushq %rax\n" | |
603 | " pushq %r8\n" | |
604 | " pushq %r9\n" | |
605 | " pushq %r10\n" | |
606 | " pushq %r11\n" | |
607 | " pushq %rbx\n" | |
608 | " pushq %rbp\n" | |
609 | " pushq %r12\n" | |
610 | " pushq %r13\n" | |
611 | " pushq %r14\n" | |
612 | " pushq %r15\n" | |
613 | " movq %rsp, %rdi\n" | |
614 | " call trampoline_handler\n" | |
615 | /* Replace saved sp with true return address. */ | |
616 | " movq %rax, 152(%rsp)\n" | |
617 | " popq %r15\n" | |
618 | " popq %r14\n" | |
619 | " popq %r13\n" | |
620 | " popq %r12\n" | |
621 | " popq %rbp\n" | |
622 | " popq %rbx\n" | |
623 | " popq %r11\n" | |
624 | " popq %r10\n" | |
625 | " popq %r9\n" | |
626 | " popq %r8\n" | |
627 | " popq %rax\n" | |
628 | " popq %rcx\n" | |
629 | " popq %rdx\n" | |
630 | " popq %rsi\n" | |
631 | " popq %rdi\n" | |
632 | /* Skip orig_ax, ip, cs */ | |
633 | " addq $24, %rsp\n" | |
634 | " popfq\n" | |
d6be29b8 MH |
635 | #else |
636 | " pushf\n" | |
637 | /* | |
638 | * Skip cs, ip, orig_ax. | |
639 | * trampoline_handler() will plug in these values | |
640 | */ | |
641 | " subl $12, %esp\n" | |
642 | " pushl %fs\n" | |
643 | " pushl %ds\n" | |
644 | " pushl %es\n" | |
645 | " pushl %eax\n" | |
646 | " pushl %ebp\n" | |
647 | " pushl %edi\n" | |
648 | " pushl %esi\n" | |
649 | " pushl %edx\n" | |
650 | " pushl %ecx\n" | |
651 | " pushl %ebx\n" | |
652 | " movl %esp, %eax\n" | |
653 | " call trampoline_handler\n" | |
654 | /* Move flags to cs */ | |
655 | " movl 52(%esp), %edx\n" | |
656 | " movl %edx, 48(%esp)\n" | |
657 | /* Replace saved flags with true return address. */ | |
658 | " movl %eax, 52(%esp)\n" | |
659 | " popl %ebx\n" | |
660 | " popl %ecx\n" | |
661 | " popl %edx\n" | |
662 | " popl %esi\n" | |
663 | " popl %edi\n" | |
664 | " popl %ebp\n" | |
665 | " popl %eax\n" | |
666 | /* Skip ip, orig_ax, es, ds, fs */ | |
667 | " addl $20, %esp\n" | |
668 | " popf\n" | |
669 | #endif | |
da07ab03 | 670 | " ret\n"); |
1017579a | 671 | } |
73649dab RL |
672 | |
673 | /* | |
da07ab03 | 674 | * Called from kretprobe_trampoline |
73649dab | 675 | */ |
f1452d42 | 676 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 677 | { |
62c27be0 | 678 | struct kretprobe_instance *ri = NULL; |
99219a3f | 679 | struct hlist_head *head, empty_rp; |
62c27be0 | 680 | struct hlist_node *node, *tmp; |
991a51d8 | 681 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 682 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
73649dab | 683 | |
99219a3f | 684 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 685 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 686 | head = kretprobe_inst_table_head(current); |
8533bbe9 | 687 | /* fixup registers */ |
d6be29b8 | 688 | #ifdef CONFIG_X86_64 |
da07ab03 | 689 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
690 | #else |
691 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
692 | #endif | |
da07ab03 | 693 | regs->ip = trampoline_address; |
8533bbe9 | 694 | regs->orig_ax = ~0UL; |
73649dab | 695 | |
ba8af12f RL |
696 | /* |
697 | * It is possible to have multiple instances associated with a given | |
8533bbe9 MH |
698 | * task either because multiple functions in the call path have |
699 | * return probes installed on them, and/or more then one | |
ba8af12f RL |
700 | * return probe was registered for a target function. |
701 | * | |
702 | * We can handle this because: | |
8533bbe9 | 703 | * - instances are always pushed into the head of the list |
ba8af12f | 704 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
705 | * function, the (chronologically) first instance's ret_addr |
706 | * will be the real return address, and all the rest will | |
707 | * point to kretprobe_trampoline. | |
ba8af12f RL |
708 | */ |
709 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 710 | if (ri->task != current) |
ba8af12f | 711 | /* another task is sharing our hash bucket */ |
62c27be0 | 712 | continue; |
ba8af12f | 713 | |
da07ab03 MH |
714 | if (ri->rp && ri->rp->handler) { |
715 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
716 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 717 | ri->rp->handler(ri, regs); |
da07ab03 MH |
718 | __get_cpu_var(current_kprobe) = NULL; |
719 | } | |
ba8af12f RL |
720 | |
721 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 722 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
723 | |
724 | if (orig_ret_address != trampoline_address) | |
725 | /* | |
726 | * This is the real return address. Any other | |
727 | * instances associated with this task are for | |
728 | * other calls deeper on the call stack | |
729 | */ | |
730 | break; | |
73649dab | 731 | } |
ba8af12f | 732 | |
0f95b7fc | 733 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 734 | |
991a51d8 | 735 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
ba8af12f | 736 | |
99219a3f | 737 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
738 | hlist_del(&ri->hlist); | |
739 | kfree(ri); | |
740 | } | |
da07ab03 | 741 | return (void *)orig_ret_address; |
73649dab RL |
742 | } |
743 | ||
1da177e4 LT |
744 | /* |
745 | * Called after single-stepping. p->addr is the address of the | |
746 | * instruction whose first byte has been replaced by the "int 3" | |
747 | * instruction. To avoid the SMP problems that can occur when we | |
748 | * temporarily put back the original opcode to single-step, we | |
749 | * single-stepped a copy of the instruction. The address of this | |
750 | * copy is p->ainsn.insn. | |
751 | * | |
752 | * This function prepares to return from the post-single-step | |
753 | * interrupt. We have to fix up the stack as follows: | |
754 | * | |
755 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 756 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
757 | * it relative to the original instruction. |
758 | * | |
759 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 760 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
761 | * |
762 | * 2) If the single-stepped instruction was a call, the return address | |
763 | * that is atop the stack is the address following the copied instruction. | |
764 | * We need to make it the address following the original instruction. | |
aa470140 MH |
765 | * |
766 | * If this is the first time we've single-stepped the instruction at | |
767 | * this probepoint, and the instruction is boostable, boost it: add a | |
768 | * jump instruction after the copied instruction, that jumps to the next | |
769 | * instruction after the probepoint. | |
1da177e4 | 770 | */ |
e7a510f9 AM |
771 | static void __kprobes resume_execution(struct kprobe *p, |
772 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 773 | { |
8533bbe9 MH |
774 | unsigned long *tos = stack_addr(regs); |
775 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
776 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
777 | kprobe_opcode_t *insn = p->ainsn.insn; |
778 | ||
779 | /*skip the REX prefix*/ | |
9930927f | 780 | if (is_REX_prefix(insn)) |
1da177e4 LT |
781 | insn++; |
782 | ||
053de044 | 783 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 784 | switch (*insn) { |
0b0122fa | 785 | case 0x9c: /* pushfl */ |
053de044 | 786 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 787 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 788 | break; |
0b0122fa MH |
789 | case 0xc2: /* iret/ret/lret */ |
790 | case 0xc3: | |
0b9e2cac | 791 | case 0xca: |
0b0122fa MH |
792 | case 0xcb: |
793 | case 0xcf: | |
794 | case 0xea: /* jmp absolute -- ip is correct */ | |
795 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 796 | p->ainsn.boostable = 1; |
0b0122fa MH |
797 | goto no_change; |
798 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 799 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 800 | break; |
e7b5e11e | 801 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
802 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
803 | *tos = orig_ip + (*tos - copy_ip); | |
804 | goto no_change; | |
805 | #endif | |
1da177e4 | 806 | case 0xff: |
dc49e344 | 807 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
808 | /* |
809 | * call absolute, indirect | |
810 | * Fix return addr; ip is correct. | |
811 | * But this is not boostable | |
812 | */ | |
813 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 814 | goto no_change; |
8533bbe9 MH |
815 | } else if (((insn[1] & 0x31) == 0x20) || |
816 | ((insn[1] & 0x31) == 0x21)) { | |
817 | /* | |
818 | * jmp near and far, absolute indirect | |
819 | * ip is correct. And this is boostable | |
820 | */ | |
aa470140 | 821 | p->ainsn.boostable = 1; |
0b0122fa | 822 | goto no_change; |
1da177e4 | 823 | } |
1da177e4 LT |
824 | default: |
825 | break; | |
826 | } | |
827 | ||
aa470140 | 828 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
829 | if ((regs->ip > copy_ip) && |
830 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
831 | /* |
832 | * These instructions can be executed directly if it | |
833 | * jumps back to correct address. | |
834 | */ | |
835 | set_jmp_op((void *)regs->ip, | |
8533bbe9 | 836 | (void *)orig_ip + (regs->ip - copy_ip)); |
aa470140 MH |
837 | p->ainsn.boostable = 1; |
838 | } else { | |
839 | p->ainsn.boostable = -1; | |
840 | } | |
841 | } | |
842 | ||
8533bbe9 | 843 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 844 | |
0b0122fa | 845 | no_change: |
1ecc798c | 846 | restore_btf(); |
1da177e4 LT |
847 | } |
848 | ||
8533bbe9 MH |
849 | /* |
850 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
851 | * remain disabled thoroughout this function. | |
852 | */ | |
853 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 854 | { |
e7a510f9 AM |
855 | struct kprobe *cur = kprobe_running(); |
856 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
857 | ||
858 | if (!cur) | |
1da177e4 LT |
859 | return 0; |
860 | ||
acb5b8a2 YL |
861 | resume_execution(cur, regs, kcb); |
862 | regs->flags |= kcb->kprobe_saved_flags; | |
863 | trace_hardirqs_fixup_flags(regs->flags); | |
864 | ||
e7a510f9 AM |
865 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
866 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
867 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 868 | } |
1da177e4 | 869 | |
8533bbe9 | 870 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
871 | if (kcb->kprobe_status == KPROBE_REENTER) { |
872 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 873 | goto out; |
aa3d7e3d | 874 | } |
e7a510f9 | 875 | reset_current_kprobe(); |
aa3d7e3d | 876 | out: |
1da177e4 LT |
877 | preempt_enable_no_resched(); |
878 | ||
879 | /* | |
65ea5b03 | 880 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
881 | * will have TF set, in which case, continue the remaining processing |
882 | * of do_debug, as if this is not a probe hit. | |
883 | */ | |
053de044 | 884 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
885 | return 0; |
886 | ||
887 | return 1; | |
888 | } | |
889 | ||
0f2fbdcb | 890 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 891 | { |
e7a510f9 AM |
892 | struct kprobe *cur = kprobe_running(); |
893 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
894 | ||
d6be29b8 | 895 | switch (kcb->kprobe_status) { |
c28f8966 PP |
896 | case KPROBE_HIT_SS: |
897 | case KPROBE_REENTER: | |
898 | /* | |
899 | * We are here because the instruction being single | |
900 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 901 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
902 | * and allow the page fault handler to continue as a |
903 | * normal page fault. | |
904 | */ | |
65ea5b03 | 905 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 906 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
907 | if (kcb->kprobe_status == KPROBE_REENTER) |
908 | restore_previous_kprobe(kcb); | |
909 | else | |
910 | reset_current_kprobe(); | |
1da177e4 | 911 | preempt_enable_no_resched(); |
c28f8966 PP |
912 | break; |
913 | case KPROBE_HIT_ACTIVE: | |
914 | case KPROBE_HIT_SSDONE: | |
915 | /* | |
916 | * We increment the nmissed count for accounting, | |
8533bbe9 | 917 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
918 | * these specific fault cases. |
919 | */ | |
920 | kprobes_inc_nmissed_count(cur); | |
921 | ||
922 | /* | |
923 | * We come here because instructions in the pre/post | |
924 | * handler caused the page_fault, this could happen | |
925 | * if handler tries to access user space by | |
926 | * copy_from_user(), get_user() etc. Let the | |
927 | * user-specified handler try to fix it first. | |
928 | */ | |
929 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
930 | return 1; | |
931 | ||
932 | /* | |
933 | * In case the user-specified fault handler returned | |
934 | * zero, try to fix up. | |
935 | */ | |
d6be29b8 MH |
936 | if (fixup_exception(regs)) |
937 | return 1; | |
6d48583b | 938 | |
c28f8966 | 939 | /* |
8533bbe9 | 940 | * fixup routine could not handle it, |
c28f8966 PP |
941 | * Let do_page_fault() fix it. |
942 | */ | |
943 | break; | |
944 | default: | |
945 | break; | |
1da177e4 LT |
946 | } |
947 | return 0; | |
948 | } | |
949 | ||
950 | /* | |
951 | * Wrapper routine for handling exceptions. | |
952 | */ | |
0f2fbdcb PP |
953 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
954 | unsigned long val, void *data) | |
1da177e4 | 955 | { |
ade1af77 | 956 | struct die_args *args = data; |
66ff2d06 AM |
957 | int ret = NOTIFY_DONE; |
958 | ||
8533bbe9 | 959 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 960 | return ret; |
961 | ||
1da177e4 LT |
962 | switch (val) { |
963 | case DIE_INT3: | |
964 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 965 | ret = NOTIFY_STOP; |
1da177e4 LT |
966 | break; |
967 | case DIE_DEBUG: | |
968 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 969 | ret = NOTIFY_STOP; |
1da177e4 LT |
970 | break; |
971 | case DIE_GPF: | |
b506a9d0 QB |
972 | /* |
973 | * To be potentially processing a kprobe fault and to | |
974 | * trust the result from kprobe_running(), we have | |
975 | * be non-preemptible. | |
976 | */ | |
977 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 978 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 979 | ret = NOTIFY_STOP; |
1da177e4 LT |
980 | break; |
981 | default: | |
982 | break; | |
983 | } | |
66ff2d06 | 984 | return ret; |
1da177e4 LT |
985 | } |
986 | ||
0f2fbdcb | 987 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
988 | { |
989 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
990 | unsigned long addr; | |
e7a510f9 | 991 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 992 | |
e7a510f9 | 993 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
994 | kcb->jprobe_saved_sp = stack_addr(regs); |
995 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
996 | ||
1da177e4 LT |
997 | /* |
998 | * As Linus pointed out, gcc assumes that the callee | |
999 | * owns the argument space and could overwrite it, e.g. | |
1000 | * tailcall optimization. So, to be absolutely safe | |
1001 | * we also save and restore enough stack bytes to cover | |
1002 | * the argument area. | |
1003 | */ | |
e7a510f9 | 1004 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1005 | MIN_STACK_SIZE(addr)); |
053de044 | 1006 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1007 | trace_hardirqs_off(); |
65ea5b03 | 1008 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
1009 | return 1; |
1010 | } | |
1011 | ||
0f2fbdcb | 1012 | void __kprobes jprobe_return(void) |
1da177e4 | 1013 | { |
e7a510f9 AM |
1014 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1015 | ||
d6be29b8 MH |
1016 | asm volatile ( |
1017 | #ifdef CONFIG_X86_64 | |
1018 | " xchg %%rbx,%%rsp \n" | |
1019 | #else | |
1020 | " xchgl %%ebx,%%esp \n" | |
1021 | #endif | |
1022 | " int3 \n" | |
1023 | " .globl jprobe_return_end\n" | |
1024 | " jprobe_return_end: \n" | |
1025 | " nop \n"::"b" | |
1026 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1027 | } |
1028 | ||
0f2fbdcb | 1029 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1030 | { |
e7a510f9 | 1031 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1032 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1033 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1034 | ||
d6be29b8 MH |
1035 | if ((addr > (u8 *) jprobe_return) && |
1036 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1037 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1038 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1039 | printk(KERN_ERR |
1040 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1041 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1042 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1043 | show_registers(saved_regs); |
d6be29b8 | 1044 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1045 | show_registers(regs); |
1046 | BUG(); | |
1047 | } | |
e7a510f9 | 1048 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1049 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1050 | kcb->jprobes_stack, | |
1051 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1052 | preempt_enable_no_resched(); |
1da177e4 LT |
1053 | return 1; |
1054 | } | |
1055 | return 0; | |
1056 | } | |
ba8af12f | 1057 | |
6772926b | 1058 | int __init arch_init_kprobes(void) |
ba8af12f | 1059 | { |
da07ab03 | 1060 | return 0; |
ba8af12f | 1061 | } |
bf8f6e5b AM |
1062 | |
1063 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1064 | { | |
bf8f6e5b AM |
1065 | return 0; |
1066 | } |