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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> | |
47 | #include <linux/preempt.h> | |
c28f8966 | 48 | #include <linux/module.h> |
1eeb66a1 | 49 | #include <linux/kdebug.h> |
9ec4b1f3 | 50 | |
8533bbe9 MH |
51 | #include <asm/cacheflush.h> |
52 | #include <asm/desc.h> | |
1da177e4 | 53 | #include <asm/pgtable.h> |
c28f8966 | 54 | #include <asm/uaccess.h> |
19d36ccd | 55 | #include <asm/alternative.h> |
1da177e4 | 56 | |
1da177e4 LT |
57 | void jprobe_return_end(void); |
58 | ||
e7a510f9 AM |
59 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
60 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 61 | |
d6be29b8 | 62 | #ifdef CONFIG_X86_64 |
8533bbe9 | 63 | #define stack_addr(regs) ((unsigned long *)regs->sp) |
d6be29b8 MH |
64 | #else |
65 | /* | |
66 | * "®s->sp" looks wrong, but it's correct for x86_32. x86_32 CPUs | |
67 | * don't save the ss and esp registers if the CPU is already in kernel | |
68 | * mode when it traps. So for kprobes, regs->sp and regs->ss are not | |
69 | * the [nonexistent] saved stack pointer and ss register, but rather | |
70 | * the top 8 bytes of the pre-int3 stack. So ®s->sp happens to | |
71 | * point to the top of the pre-int3 stack. | |
72 | */ | |
73 | #define stack_addr(regs) ((unsigned long *)®s->sp) | |
74 | #endif | |
8533bbe9 MH |
75 | |
76 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
77 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
78 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
79 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
80 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
81 | << (row % 32)) | |
82 | /* | |
83 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
84 | * Groups, and some special opcodes can not boost. | |
85 | */ | |
86 | static const u32 twobyte_is_boostable[256 / 32] = { | |
87 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
88 | /* ---------------------------------------------- */ | |
89 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
90 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ | |
91 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ | |
92 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
93 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
94 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
95 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
96 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
97 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
98 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
99 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
100 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
101 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
102 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
103 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
104 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
105 | /* ----------------------------------------------- */ | |
106 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
107 | }; | |
108 | static const u32 onebyte_has_modrm[256 / 32] = { | |
109 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
110 | /* ----------------------------------------------- */ | |
111 | W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 00 */ | |
112 | W(0x10, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 10 */ | |
113 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 20 */ | |
114 | W(0x30, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) , /* 30 */ | |
115 | W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */ | |
116 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
117 | W(0x60, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0) | /* 60 */ | |
118 | W(0x70, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 70 */ | |
119 | W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */ | |
120 | W(0x90, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 90 */ | |
121 | W(0xa0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* a0 */ | |
122 | W(0xb0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* b0 */ | |
123 | W(0xc0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* c0 */ | |
124 | W(0xd0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */ | |
125 | W(0xe0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* e0 */ | |
126 | W(0xf0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) /* f0 */ | |
127 | /* ----------------------------------------------- */ | |
128 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
129 | }; | |
130 | static const u32 twobyte_has_modrm[256 / 32] = { | |
131 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
132 | /* ----------------------------------------------- */ | |
133 | W(0x00, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1) | /* 0f */ | |
134 | W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0) , /* 1f */ | |
135 | W(0x20, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 2f */ | |
136 | W(0x30, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 3f */ | |
137 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 4f */ | |
138 | W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 5f */ | |
139 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 6f */ | |
140 | W(0x70, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1) , /* 7f */ | |
141 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 8f */ | |
142 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 9f */ | |
143 | W(0xa0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) | /* af */ | |
144 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1) , /* bf */ | |
145 | W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0) | /* cf */ | |
146 | W(0xd0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* df */ | |
147 | W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* ef */ | |
148 | W(0xf0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0) /* ff */ | |
149 | /* ----------------------------------------------- */ | |
150 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
151 | }; | |
152 | #undef W | |
153 | ||
f438d914 MH |
154 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
155 | {"__switch_to", }, /* This function switches only current task, but | |
156 | doesn't switch kernel stack.*/ | |
157 | {NULL, NULL} /* Terminator */ | |
158 | }; | |
159 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); | |
160 | ||
aa470140 MH |
161 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
162 | static __always_inline void set_jmp_op(void *from, void *to) | |
163 | { | |
164 | struct __arch_jmp_op { | |
165 | char op; | |
166 | s32 raddr; | |
167 | } __attribute__((packed)) * jop; | |
168 | jop = (struct __arch_jmp_op *)from; | |
169 | jop->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
170 | jop->op = RELATIVEJUMP_INSTRUCTION; | |
171 | } | |
172 | ||
173 | /* | |
d6be29b8 MH |
174 | * Returns non-zero if opcode is boostable. |
175 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 MH |
176 | */ |
177 | static __always_inline int can_boost(kprobe_opcode_t *opcodes) | |
178 | { | |
aa470140 MH |
179 | kprobe_opcode_t opcode; |
180 | kprobe_opcode_t *orig_opcodes = opcodes; | |
181 | ||
182 | retry: | |
183 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
184 | return 0; | |
185 | opcode = *(opcodes++); | |
186 | ||
187 | /* 2nd-byte opcode */ | |
188 | if (opcode == 0x0f) { | |
189 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
190 | return 0; | |
8533bbe9 MH |
191 | return test_bit(*opcodes, |
192 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
193 | } |
194 | ||
195 | switch (opcode & 0xf0) { | |
d6be29b8 | 196 | #ifdef CONFIG_X86_64 |
aa470140 MH |
197 | case 0x40: |
198 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 199 | #endif |
aa470140 MH |
200 | case 0x60: |
201 | if (0x63 < opcode && opcode < 0x67) | |
202 | goto retry; /* prefixes */ | |
203 | /* can't boost Address-size override and bound */ | |
204 | return (opcode != 0x62 && opcode != 0x67); | |
205 | case 0x70: | |
206 | return 0; /* can't boost conditional jump */ | |
207 | case 0xc0: | |
208 | /* can't boost software-interruptions */ | |
209 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
210 | case 0xd0: | |
211 | /* can boost AA* and XLAT */ | |
212 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
213 | case 0xe0: | |
214 | /* can boost in/out and absolute jmps */ | |
215 | return ((opcode & 0x04) || opcode == 0xea); | |
216 | case 0xf0: | |
217 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
218 | goto retry; /* lock/rep(ne) prefix */ | |
219 | /* clear and set flags are boostable */ | |
220 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
221 | default: | |
222 | /* segment override prefixes are boostable */ | |
223 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
224 | goto retry; /* prefixes */ | |
225 | /* CS override prefix and call are not boostable */ | |
226 | return (opcode != 0x2e && opcode != 0x9a); | |
227 | } | |
228 | } | |
229 | ||
1da177e4 | 230 | /* |
d6be29b8 | 231 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 232 | */ |
8645419c | 233 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 LT |
234 | { |
235 | switch (*insn) { | |
236 | case 0xfa: /* cli */ | |
237 | case 0xfb: /* sti */ | |
238 | case 0xcf: /* iret/iretd */ | |
239 | case 0x9d: /* popf/popfd */ | |
240 | return 1; | |
241 | } | |
d6be29b8 | 242 | #ifdef CONFIG_X86_64 |
8533bbe9 MH |
243 | /* |
244 | * on 64 bit x86, 0x40-0x4f are prefixes so we need to look | |
245 | * at the next byte instead.. but of course not recurse infinitely | |
246 | */ | |
247 | if (*insn >= 0x40 && *insn <= 0x4f) | |
248 | return is_IF_modifier(++insn); | |
d6be29b8 | 249 | #endif |
1da177e4 LT |
250 | return 0; |
251 | } | |
252 | ||
d6be29b8 | 253 | #ifdef CONFIG_X86_64 |
1da177e4 | 254 | /* |
8533bbe9 MH |
255 | * Adjust the displacement if the instruction uses the %rip-relative |
256 | * addressing mode. | |
aa470140 | 257 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 LT |
258 | * If not, return null. |
259 | */ | |
8533bbe9 | 260 | static void __kprobes fix_riprel(struct kprobe *p) |
1da177e4 | 261 | { |
8533bbe9 MH |
262 | u8 *insn = p->ainsn.insn; |
263 | s64 disp; | |
1da177e4 LT |
264 | int need_modrm; |
265 | ||
266 | /* Skip legacy instruction prefixes. */ | |
267 | while (1) { | |
268 | switch (*insn) { | |
269 | case 0x66: | |
270 | case 0x67: | |
271 | case 0x2e: | |
272 | case 0x3e: | |
273 | case 0x26: | |
274 | case 0x64: | |
275 | case 0x65: | |
276 | case 0x36: | |
277 | case 0xf0: | |
278 | case 0xf3: | |
279 | case 0xf2: | |
280 | ++insn; | |
281 | continue; | |
282 | } | |
283 | break; | |
284 | } | |
285 | ||
286 | /* Skip REX instruction prefix. */ | |
287 | if ((*insn & 0xf0) == 0x40) | |
288 | ++insn; | |
289 | ||
d6be29b8 MH |
290 | if (*insn == 0x0f) { |
291 | /* Two-byte opcode. */ | |
1da177e4 | 292 | ++insn; |
8533bbe9 MH |
293 | need_modrm = test_bit(*insn, |
294 | (unsigned long *)twobyte_has_modrm); | |
d6be29b8 MH |
295 | } else |
296 | /* One-byte opcode. */ | |
8533bbe9 MH |
297 | need_modrm = test_bit(*insn, |
298 | (unsigned long *)onebyte_has_modrm); | |
1da177e4 LT |
299 | |
300 | if (need_modrm) { | |
301 | u8 modrm = *++insn; | |
d6be29b8 MH |
302 | if ((modrm & 0xc7) == 0x05) { |
303 | /* %rip+disp32 addressing mode */ | |
1da177e4 | 304 | /* Displacement follows ModRM byte. */ |
8533bbe9 MH |
305 | ++insn; |
306 | /* | |
307 | * The copied instruction uses the %rip-relative | |
308 | * addressing mode. Adjust the displacement for the | |
309 | * difference between the original location of this | |
310 | * instruction and the location of the copy that will | |
311 | * actually be run. The tricky bit here is making sure | |
312 | * that the sign extension happens correctly in this | |
313 | * calculation, since we need a signed 32-bit result to | |
314 | * be sign-extended to 64 bits when it's added to the | |
315 | * %rip value and yield the same 64-bit result that the | |
316 | * sign-extension of the original signed 32-bit | |
317 | * displacement would have given. | |
318 | */ | |
319 | disp = (u8 *) p->addr + *((s32 *) insn) - | |
320 | (u8 *) p->ainsn.insn; | |
321 | BUG_ON((s64) (s32) disp != disp); /* Sanity check. */ | |
322 | *(s32 *)insn = (s32) disp; | |
1da177e4 LT |
323 | } |
324 | } | |
1da177e4 | 325 | } |
d6be29b8 | 326 | #endif |
1da177e4 | 327 | |
f709b122 | 328 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 329 | { |
8533bbe9 | 330 | memcpy(p->ainsn.insn, p->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
d6be29b8 | 331 | #ifdef CONFIG_X86_64 |
8533bbe9 | 332 | fix_riprel(p); |
d6be29b8 | 333 | #endif |
8533bbe9 | 334 | if (can_boost(p->addr)) |
aa470140 | 335 | p->ainsn.boostable = 0; |
8533bbe9 | 336 | else |
aa470140 | 337 | p->ainsn.boostable = -1; |
8533bbe9 | 338 | |
7e1048b1 | 339 | p->opcode = *p->addr; |
1da177e4 LT |
340 | } |
341 | ||
8533bbe9 MH |
342 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
343 | { | |
344 | /* insn: must be on special executable page on x86. */ | |
345 | p->ainsn.insn = get_insn_slot(); | |
346 | if (!p->ainsn.insn) | |
347 | return -ENOMEM; | |
348 | arch_copy_kprobe(p); | |
349 | return 0; | |
350 | } | |
351 | ||
0f2fbdcb | 352 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 353 | { |
19d36ccd | 354 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
355 | } |
356 | ||
0f2fbdcb | 357 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 358 | { |
19d36ccd | 359 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
360 | } |
361 | ||
0498b635 | 362 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 363 | { |
7a7d1cf9 | 364 | mutex_lock(&kprobe_mutex); |
aa470140 | 365 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); |
7a7d1cf9 | 366 | mutex_unlock(&kprobe_mutex); |
1da177e4 LT |
367 | } |
368 | ||
3b60211c | 369 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 370 | { |
e7a510f9 AM |
371 | kcb->prev_kprobe.kp = kprobe_running(); |
372 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
373 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
374 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
375 | } |
376 | ||
3b60211c | 377 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 378 | { |
e7a510f9 AM |
379 | __get_cpu_var(current_kprobe) = kcb->prev_kprobe.kp; |
380 | kcb->kprobe_status = kcb->prev_kprobe.status; | |
8533bbe9 MH |
381 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
382 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
383 | } |
384 | ||
3b60211c | 385 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 386 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 387 | { |
e7a510f9 | 388 | __get_cpu_var(current_kprobe) = p; |
8533bbe9 | 389 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 390 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
aa3d7e3d | 391 | if (is_IF_modifier(p->ainsn.insn)) |
053de044 | 392 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
393 | } |
394 | ||
1ecc798c RM |
395 | static __always_inline void clear_btf(void) |
396 | { | |
397 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
d6be29b8 | 398 | wrmsr(MSR_IA32_DEBUGCTLMSR, 0, 0); |
1ecc798c RM |
399 | } |
400 | ||
401 | static __always_inline void restore_btf(void) | |
402 | { | |
403 | if (test_thread_flag(TIF_DEBUGCTLMSR)) | |
d6be29b8 | 404 | wrmsr(MSR_IA32_DEBUGCTLMSR, current->thread.debugctlmsr, 0); |
1ecc798c RM |
405 | } |
406 | ||
0f2fbdcb | 407 | static void __kprobes prepare_singlestep(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 408 | { |
1ecc798c | 409 | clear_btf(); |
053de044 GOC |
410 | regs->flags |= X86_EFLAGS_TF; |
411 | regs->flags &= ~X86_EFLAGS_IF; | |
1da177e4 LT |
412 | /*single step inline if the instruction is an int3*/ |
413 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
65ea5b03 | 414 | regs->ip = (unsigned long)p->addr; |
1da177e4 | 415 | else |
65ea5b03 | 416 | regs->ip = (unsigned long)p->ainsn.insn; |
1da177e4 LT |
417 | } |
418 | ||
991a51d8 | 419 | /* Called with kretprobe_lock held */ |
4c4308cb | 420 | void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, |
0f2fbdcb | 421 | struct pt_regs *regs) |
73649dab | 422 | { |
8533bbe9 | 423 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 424 | |
4c4308cb | 425 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 426 | |
4c4308cb CH |
427 | /* Replace the return addr with trampoline addr */ |
428 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab RL |
429 | } |
430 | ||
8533bbe9 MH |
431 | /* |
432 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
433 | * remain disabled thorough out this function. | |
434 | */ | |
435 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 LT |
436 | { |
437 | struct kprobe *p; | |
438 | int ret = 0; | |
8533bbe9 | 439 | kprobe_opcode_t *addr; |
d217d545 AM |
440 | struct kprobe_ctlblk *kcb; |
441 | ||
8533bbe9 MH |
442 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
443 | ||
d217d545 AM |
444 | /* |
445 | * We don't want to be preempted for the entire | |
446 | * duration of kprobe processing | |
447 | */ | |
448 | preempt_disable(); | |
449 | kcb = get_kprobe_ctlblk(); | |
1da177e4 | 450 | |
1da177e4 LT |
451 | /* Check we're not actually recursing */ |
452 | if (kprobe_running()) { | |
1da177e4 LT |
453 | p = get_kprobe(addr); |
454 | if (p) { | |
e7a510f9 | 455 | if (kcb->kprobe_status == KPROBE_HIT_SS && |
deac66ae | 456 | *p->ainsn.insn == BREAKPOINT_INSTRUCTION) { |
053de044 | 457 | regs->flags &= ~X86_EFLAGS_TF; |
8533bbe9 | 458 | regs->flags |= kcb->kprobe_saved_flags; |
1da177e4 | 459 | goto no_kprobe; |
d6be29b8 | 460 | #ifdef CONFIG_X86_64 |
e7a510f9 | 461 | } else if (kcb->kprobe_status == KPROBE_HIT_SSDONE) { |
aa3d7e3d PP |
462 | /* TODO: Provide re-entrancy from |
463 | * post_kprobes_handler() and avoid exception | |
464 | * stack corruption while single-stepping on | |
465 | * the instruction of the new probe. | |
466 | */ | |
467 | arch_disarm_kprobe(p); | |
65ea5b03 | 468 | regs->ip = (unsigned long)p->addr; |
e7a510f9 | 469 | reset_current_kprobe(); |
aa3d7e3d | 470 | return 1; |
d6be29b8 | 471 | #endif |
1da177e4 | 472 | } |
8533bbe9 MH |
473 | /* We have reentered the kprobe_handler(), since |
474 | * another probe was hit while within the handler. | |
475 | * We here save the original kprobes variables and | |
476 | * just single step on the instruction of the new probe | |
477 | * without calling any user handlers. | |
478 | */ | |
479 | save_previous_kprobe(kcb); | |
480 | set_current_kprobe(p, regs, kcb); | |
481 | kprobes_inc_nmissed_count(p); | |
482 | prepare_singlestep(p, regs); | |
483 | kcb->kprobe_status = KPROBE_REENTER; | |
484 | return 1; | |
1da177e4 | 485 | } else { |
eb3a7292 KA |
486 | if (*addr != BREAKPOINT_INSTRUCTION) { |
487 | /* The breakpoint instruction was removed by | |
488 | * another cpu right after we hit, no further | |
489 | * handling of this interrupt is appropriate | |
490 | */ | |
65ea5b03 | 491 | regs->ip = (unsigned long)addr; |
eb3a7292 KA |
492 | ret = 1; |
493 | goto no_kprobe; | |
494 | } | |
e7a510f9 | 495 | p = __get_cpu_var(current_kprobe); |
d6be29b8 | 496 | if (p->break_handler && p->break_handler(p, regs)) |
1da177e4 | 497 | goto ss_probe; |
1da177e4 | 498 | } |
1da177e4 LT |
499 | goto no_kprobe; |
500 | } | |
501 | ||
1da177e4 LT |
502 | p = get_kprobe(addr); |
503 | if (!p) { | |
1da177e4 LT |
504 | if (*addr != BREAKPOINT_INSTRUCTION) { |
505 | /* | |
506 | * The breakpoint instruction was removed right | |
507 | * after we hit it. Another cpu has removed | |
508 | * either a probepoint or a debugger breakpoint | |
509 | * at this address. In either case, no further | |
510 | * handling of this interrupt is appropriate. | |
bce06494 JK |
511 | * Back up over the (now missing) int3 and run |
512 | * the original instruction. | |
1da177e4 | 513 | */ |
65ea5b03 | 514 | regs->ip = (unsigned long)addr; |
1da177e4 LT |
515 | ret = 1; |
516 | } | |
517 | /* Not one of ours: let kernel handle it */ | |
518 | goto no_kprobe; | |
519 | } | |
520 | ||
e7a510f9 AM |
521 | set_current_kprobe(p, regs, kcb); |
522 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
1da177e4 LT |
523 | |
524 | if (p->pre_handler && p->pre_handler(p, regs)) | |
525 | /* handler has already set things up, so skip ss setup */ | |
526 | return 1; | |
527 | ||
528 | ss_probe: | |
aa470140 MH |
529 | #if !defined(CONFIG_PREEMPT) || defined(CONFIG_PM) |
530 | if (p->ainsn.boostable == 1 && !p->post_handler) { | |
531 | /* Boost up -- we can execute copied instructions directly */ | |
532 | reset_current_kprobe(); | |
533 | regs->ip = (unsigned long)p->ainsn.insn; | |
534 | preempt_enable_no_resched(); | |
535 | return 1; | |
536 | } | |
537 | #endif | |
1da177e4 | 538 | prepare_singlestep(p, regs); |
e7a510f9 | 539 | kcb->kprobe_status = KPROBE_HIT_SS; |
1da177e4 LT |
540 | return 1; |
541 | ||
542 | no_kprobe: | |
d217d545 | 543 | preempt_enable_no_resched(); |
1da177e4 LT |
544 | return ret; |
545 | } | |
546 | ||
73649dab | 547 | /* |
da07ab03 MH |
548 | * When a retprobed function returns, this code saves registers and |
549 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 550 | */ |
da07ab03 | 551 | void __kprobes kretprobe_trampoline_holder(void) |
73649dab | 552 | { |
d6be29b8 MH |
553 | asm volatile ( |
554 | ".global kretprobe_trampoline\n" | |
da07ab03 | 555 | "kretprobe_trampoline: \n" |
d6be29b8 | 556 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
557 | /* We don't bother saving the ss register */ |
558 | " pushq %rsp\n" | |
559 | " pushfq\n" | |
560 | /* | |
561 | * Skip cs, ip, orig_ax. | |
562 | * trampoline_handler() will plug in these values | |
563 | */ | |
564 | " subq $24, %rsp\n" | |
565 | " pushq %rdi\n" | |
566 | " pushq %rsi\n" | |
567 | " pushq %rdx\n" | |
568 | " pushq %rcx\n" | |
569 | " pushq %rax\n" | |
570 | " pushq %r8\n" | |
571 | " pushq %r9\n" | |
572 | " pushq %r10\n" | |
573 | " pushq %r11\n" | |
574 | " pushq %rbx\n" | |
575 | " pushq %rbp\n" | |
576 | " pushq %r12\n" | |
577 | " pushq %r13\n" | |
578 | " pushq %r14\n" | |
579 | " pushq %r15\n" | |
580 | " movq %rsp, %rdi\n" | |
581 | " call trampoline_handler\n" | |
582 | /* Replace saved sp with true return address. */ | |
583 | " movq %rax, 152(%rsp)\n" | |
584 | " popq %r15\n" | |
585 | " popq %r14\n" | |
586 | " popq %r13\n" | |
587 | " popq %r12\n" | |
588 | " popq %rbp\n" | |
589 | " popq %rbx\n" | |
590 | " popq %r11\n" | |
591 | " popq %r10\n" | |
592 | " popq %r9\n" | |
593 | " popq %r8\n" | |
594 | " popq %rax\n" | |
595 | " popq %rcx\n" | |
596 | " popq %rdx\n" | |
597 | " popq %rsi\n" | |
598 | " popq %rdi\n" | |
599 | /* Skip orig_ax, ip, cs */ | |
600 | " addq $24, %rsp\n" | |
601 | " popfq\n" | |
d6be29b8 MH |
602 | #else |
603 | " pushf\n" | |
604 | /* | |
605 | * Skip cs, ip, orig_ax. | |
606 | * trampoline_handler() will plug in these values | |
607 | */ | |
608 | " subl $12, %esp\n" | |
609 | " pushl %fs\n" | |
610 | " pushl %ds\n" | |
611 | " pushl %es\n" | |
612 | " pushl %eax\n" | |
613 | " pushl %ebp\n" | |
614 | " pushl %edi\n" | |
615 | " pushl %esi\n" | |
616 | " pushl %edx\n" | |
617 | " pushl %ecx\n" | |
618 | " pushl %ebx\n" | |
619 | " movl %esp, %eax\n" | |
620 | " call trampoline_handler\n" | |
621 | /* Move flags to cs */ | |
622 | " movl 52(%esp), %edx\n" | |
623 | " movl %edx, 48(%esp)\n" | |
624 | /* Replace saved flags with true return address. */ | |
625 | " movl %eax, 52(%esp)\n" | |
626 | " popl %ebx\n" | |
627 | " popl %ecx\n" | |
628 | " popl %edx\n" | |
629 | " popl %esi\n" | |
630 | " popl %edi\n" | |
631 | " popl %ebp\n" | |
632 | " popl %eax\n" | |
633 | /* Skip ip, orig_ax, es, ds, fs */ | |
634 | " addl $20, %esp\n" | |
635 | " popf\n" | |
636 | #endif | |
da07ab03 | 637 | " ret\n"); |
73649dab RL |
638 | } |
639 | ||
640 | /* | |
da07ab03 | 641 | * Called from kretprobe_trampoline |
73649dab | 642 | */ |
d6be29b8 | 643 | void * __kprobes trampoline_handler(struct pt_regs *regs) |
73649dab | 644 | { |
62c27be0 | 645 | struct kretprobe_instance *ri = NULL; |
99219a3f | 646 | struct hlist_head *head, empty_rp; |
62c27be0 | 647 | struct hlist_node *node, *tmp; |
991a51d8 | 648 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 649 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
73649dab | 650 | |
99219a3f | 651 | INIT_HLIST_HEAD(&empty_rp); |
991a51d8 | 652 | spin_lock_irqsave(&kretprobe_lock, flags); |
62c27be0 | 653 | head = kretprobe_inst_table_head(current); |
8533bbe9 | 654 | /* fixup registers */ |
d6be29b8 | 655 | #ifdef CONFIG_X86_64 |
da07ab03 | 656 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
657 | #else |
658 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
659 | #endif | |
da07ab03 | 660 | regs->ip = trampoline_address; |
8533bbe9 | 661 | regs->orig_ax = ~0UL; |
73649dab | 662 | |
ba8af12f RL |
663 | /* |
664 | * It is possible to have multiple instances associated with a given | |
8533bbe9 MH |
665 | * task either because multiple functions in the call path have |
666 | * return probes installed on them, and/or more then one | |
ba8af12f RL |
667 | * return probe was registered for a target function. |
668 | * | |
669 | * We can handle this because: | |
8533bbe9 | 670 | * - instances are always pushed into the head of the list |
ba8af12f | 671 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
672 | * function, the (chronologically) first instance's ret_addr |
673 | * will be the real return address, and all the rest will | |
674 | * point to kretprobe_trampoline. | |
ba8af12f RL |
675 | */ |
676 | hlist_for_each_entry_safe(ri, node, tmp, head, hlist) { | |
62c27be0 | 677 | if (ri->task != current) |
ba8af12f | 678 | /* another task is sharing our hash bucket */ |
62c27be0 | 679 | continue; |
ba8af12f | 680 | |
da07ab03 MH |
681 | if (ri->rp && ri->rp->handler) { |
682 | __get_cpu_var(current_kprobe) = &ri->rp->kp; | |
683 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; | |
ba8af12f | 684 | ri->rp->handler(ri, regs); |
da07ab03 MH |
685 | __get_cpu_var(current_kprobe) = NULL; |
686 | } | |
ba8af12f RL |
687 | |
688 | orig_ret_address = (unsigned long)ri->ret_addr; | |
99219a3f | 689 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
690 | |
691 | if (orig_ret_address != trampoline_address) | |
692 | /* | |
693 | * This is the real return address. Any other | |
694 | * instances associated with this task are for | |
695 | * other calls deeper on the call stack | |
696 | */ | |
697 | break; | |
73649dab | 698 | } |
ba8af12f | 699 | |
0f95b7fc | 700 | kretprobe_assert(ri, orig_ret_address, trampoline_address); |
ba8af12f | 701 | |
991a51d8 | 702 | spin_unlock_irqrestore(&kretprobe_lock, flags); |
ba8af12f | 703 | |
99219a3f | 704 | hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) { |
705 | hlist_del(&ri->hlist); | |
706 | kfree(ri); | |
707 | } | |
da07ab03 | 708 | return (void *)orig_ret_address; |
73649dab RL |
709 | } |
710 | ||
1da177e4 LT |
711 | /* |
712 | * Called after single-stepping. p->addr is the address of the | |
713 | * instruction whose first byte has been replaced by the "int 3" | |
714 | * instruction. To avoid the SMP problems that can occur when we | |
715 | * temporarily put back the original opcode to single-step, we | |
716 | * single-stepped a copy of the instruction. The address of this | |
717 | * copy is p->ainsn.insn. | |
718 | * | |
719 | * This function prepares to return from the post-single-step | |
720 | * interrupt. We have to fix up the stack as follows: | |
721 | * | |
722 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 723 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
724 | * it relative to the original instruction. |
725 | * | |
726 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 727 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
728 | * |
729 | * 2) If the single-stepped instruction was a call, the return address | |
730 | * that is atop the stack is the address following the copied instruction. | |
731 | * We need to make it the address following the original instruction. | |
aa470140 MH |
732 | * |
733 | * If this is the first time we've single-stepped the instruction at | |
734 | * this probepoint, and the instruction is boostable, boost it: add a | |
735 | * jump instruction after the copied instruction, that jumps to the next | |
736 | * instruction after the probepoint. | |
1da177e4 | 737 | */ |
e7a510f9 AM |
738 | static void __kprobes resume_execution(struct kprobe *p, |
739 | struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 740 | { |
8533bbe9 MH |
741 | unsigned long *tos = stack_addr(regs); |
742 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
743 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
744 | kprobe_opcode_t *insn = p->ainsn.insn; |
745 | ||
d6be29b8 | 746 | #ifdef CONFIG_X86_64 |
1da177e4 LT |
747 | /*skip the REX prefix*/ |
748 | if (*insn >= 0x40 && *insn <= 0x4f) | |
749 | insn++; | |
d6be29b8 | 750 | #endif |
1da177e4 | 751 | |
053de044 | 752 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 753 | switch (*insn) { |
0b0122fa | 754 | case 0x9c: /* pushfl */ |
053de044 | 755 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 756 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 757 | break; |
0b0122fa MH |
758 | case 0xc2: /* iret/ret/lret */ |
759 | case 0xc3: | |
0b9e2cac | 760 | case 0xca: |
0b0122fa MH |
761 | case 0xcb: |
762 | case 0xcf: | |
763 | case 0xea: /* jmp absolute -- ip is correct */ | |
764 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 765 | p->ainsn.boostable = 1; |
0b0122fa MH |
766 | goto no_change; |
767 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 768 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 769 | break; |
d6be29b8 MH |
770 | #ifndef CONFIG_X86_64 |
771 | case 0x9a: /* call absolute -- same as call absolute, indirect */ | |
772 | *tos = orig_ip + (*tos - copy_ip); | |
773 | goto no_change; | |
774 | #endif | |
1da177e4 | 775 | case 0xff: |
dc49e344 | 776 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
777 | /* |
778 | * call absolute, indirect | |
779 | * Fix return addr; ip is correct. | |
780 | * But this is not boostable | |
781 | */ | |
782 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 783 | goto no_change; |
8533bbe9 MH |
784 | } else if (((insn[1] & 0x31) == 0x20) || |
785 | ((insn[1] & 0x31) == 0x21)) { | |
786 | /* | |
787 | * jmp near and far, absolute indirect | |
788 | * ip is correct. And this is boostable | |
789 | */ | |
aa470140 | 790 | p->ainsn.boostable = 1; |
0b0122fa | 791 | goto no_change; |
1da177e4 | 792 | } |
1da177e4 LT |
793 | default: |
794 | break; | |
795 | } | |
796 | ||
aa470140 | 797 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
798 | if ((regs->ip > copy_ip) && |
799 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
800 | /* |
801 | * These instructions can be executed directly if it | |
802 | * jumps back to correct address. | |
803 | */ | |
804 | set_jmp_op((void *)regs->ip, | |
8533bbe9 | 805 | (void *)orig_ip + (regs->ip - copy_ip)); |
aa470140 MH |
806 | p->ainsn.boostable = 1; |
807 | } else { | |
808 | p->ainsn.boostable = -1; | |
809 | } | |
810 | } | |
811 | ||
8533bbe9 | 812 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 813 | |
0b0122fa | 814 | no_change: |
1ecc798c | 815 | restore_btf(); |
0b0122fa MH |
816 | |
817 | return; | |
1da177e4 LT |
818 | } |
819 | ||
8533bbe9 MH |
820 | /* |
821 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
822 | * remain disabled thoroughout this function. | |
823 | */ | |
824 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 825 | { |
e7a510f9 AM |
826 | struct kprobe *cur = kprobe_running(); |
827 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
828 | ||
829 | if (!cur) | |
1da177e4 LT |
830 | return 0; |
831 | ||
e7a510f9 AM |
832 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
833 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
834 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 835 | } |
1da177e4 | 836 | |
e7a510f9 | 837 | resume_execution(cur, regs, kcb); |
8533bbe9 | 838 | regs->flags |= kcb->kprobe_saved_flags; |
65ea5b03 | 839 | trace_hardirqs_fixup_flags(regs->flags); |
1da177e4 | 840 | |
8533bbe9 | 841 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
842 | if (kcb->kprobe_status == KPROBE_REENTER) { |
843 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 844 | goto out; |
aa3d7e3d | 845 | } |
e7a510f9 | 846 | reset_current_kprobe(); |
aa3d7e3d | 847 | out: |
1da177e4 LT |
848 | preempt_enable_no_resched(); |
849 | ||
850 | /* | |
65ea5b03 | 851 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
852 | * will have TF set, in which case, continue the remaining processing |
853 | * of do_debug, as if this is not a probe hit. | |
854 | */ | |
053de044 | 855 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
856 | return 0; |
857 | ||
858 | return 1; | |
859 | } | |
860 | ||
0f2fbdcb | 861 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 862 | { |
e7a510f9 AM |
863 | struct kprobe *cur = kprobe_running(); |
864 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
865 | ||
d6be29b8 | 866 | switch (kcb->kprobe_status) { |
c28f8966 PP |
867 | case KPROBE_HIT_SS: |
868 | case KPROBE_REENTER: | |
869 | /* | |
870 | * We are here because the instruction being single | |
871 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 872 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
873 | * and allow the page fault handler to continue as a |
874 | * normal page fault. | |
875 | */ | |
65ea5b03 | 876 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 877 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
878 | if (kcb->kprobe_status == KPROBE_REENTER) |
879 | restore_previous_kprobe(kcb); | |
880 | else | |
881 | reset_current_kprobe(); | |
1da177e4 | 882 | preempt_enable_no_resched(); |
c28f8966 PP |
883 | break; |
884 | case KPROBE_HIT_ACTIVE: | |
885 | case KPROBE_HIT_SSDONE: | |
886 | /* | |
887 | * We increment the nmissed count for accounting, | |
8533bbe9 | 888 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
889 | * these specific fault cases. |
890 | */ | |
891 | kprobes_inc_nmissed_count(cur); | |
892 | ||
893 | /* | |
894 | * We come here because instructions in the pre/post | |
895 | * handler caused the page_fault, this could happen | |
896 | * if handler tries to access user space by | |
897 | * copy_from_user(), get_user() etc. Let the | |
898 | * user-specified handler try to fix it first. | |
899 | */ | |
900 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
901 | return 1; | |
902 | ||
903 | /* | |
904 | * In case the user-specified fault handler returned | |
905 | * zero, try to fix up. | |
906 | */ | |
d6be29b8 MH |
907 | if (fixup_exception(regs)) |
908 | return 1; | |
6d48583b | 909 | |
c28f8966 | 910 | /* |
8533bbe9 | 911 | * fixup routine could not handle it, |
c28f8966 PP |
912 | * Let do_page_fault() fix it. |
913 | */ | |
914 | break; | |
915 | default: | |
916 | break; | |
1da177e4 LT |
917 | } |
918 | return 0; | |
919 | } | |
920 | ||
921 | /* | |
922 | * Wrapper routine for handling exceptions. | |
923 | */ | |
0f2fbdcb PP |
924 | int __kprobes kprobe_exceptions_notify(struct notifier_block *self, |
925 | unsigned long val, void *data) | |
1da177e4 LT |
926 | { |
927 | struct die_args *args = (struct die_args *)data; | |
66ff2d06 AM |
928 | int ret = NOTIFY_DONE; |
929 | ||
8533bbe9 | 930 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 931 | return ret; |
932 | ||
1da177e4 LT |
933 | switch (val) { |
934 | case DIE_INT3: | |
935 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 936 | ret = NOTIFY_STOP; |
1da177e4 LT |
937 | break; |
938 | case DIE_DEBUG: | |
939 | if (post_kprobe_handler(args->regs)) | |
66ff2d06 | 940 | ret = NOTIFY_STOP; |
1da177e4 LT |
941 | break; |
942 | case DIE_GPF: | |
d217d545 AM |
943 | /* kprobe_running() needs smp_processor_id() */ |
944 | preempt_disable(); | |
1da177e4 LT |
945 | if (kprobe_running() && |
946 | kprobe_fault_handler(args->regs, args->trapnr)) | |
66ff2d06 | 947 | ret = NOTIFY_STOP; |
d217d545 | 948 | preempt_enable(); |
1da177e4 LT |
949 | break; |
950 | default: | |
951 | break; | |
952 | } | |
66ff2d06 | 953 | return ret; |
1da177e4 LT |
954 | } |
955 | ||
0f2fbdcb | 956 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
957 | { |
958 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
959 | unsigned long addr; | |
e7a510f9 | 960 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 961 | |
e7a510f9 | 962 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
963 | kcb->jprobe_saved_sp = stack_addr(regs); |
964 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
965 | ||
1da177e4 LT |
966 | /* |
967 | * As Linus pointed out, gcc assumes that the callee | |
968 | * owns the argument space and could overwrite it, e.g. | |
969 | * tailcall optimization. So, to be absolutely safe | |
970 | * we also save and restore enough stack bytes to cover | |
971 | * the argument area. | |
972 | */ | |
e7a510f9 | 973 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 974 | MIN_STACK_SIZE(addr)); |
053de044 | 975 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 976 | trace_hardirqs_off(); |
65ea5b03 | 977 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
978 | return 1; |
979 | } | |
980 | ||
0f2fbdcb | 981 | void __kprobes jprobe_return(void) |
1da177e4 | 982 | { |
e7a510f9 AM |
983 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
984 | ||
d6be29b8 MH |
985 | asm volatile ( |
986 | #ifdef CONFIG_X86_64 | |
987 | " xchg %%rbx,%%rsp \n" | |
988 | #else | |
989 | " xchgl %%ebx,%%esp \n" | |
990 | #endif | |
991 | " int3 \n" | |
992 | " .globl jprobe_return_end\n" | |
993 | " jprobe_return_end: \n" | |
994 | " nop \n"::"b" | |
995 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
996 | } |
997 | ||
0f2fbdcb | 998 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 999 | { |
e7a510f9 | 1000 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1001 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1002 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1003 | ||
d6be29b8 MH |
1004 | if ((addr > (u8 *) jprobe_return) && |
1005 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1006 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1007 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1008 | printk(KERN_ERR |
1009 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1010 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1011 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
1da177e4 | 1012 | show_registers(saved_regs); |
d6be29b8 | 1013 | printk(KERN_ERR "Current registers\n"); |
1da177e4 LT |
1014 | show_registers(regs); |
1015 | BUG(); | |
1016 | } | |
e7a510f9 | 1017 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1018 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1019 | kcb->jprobes_stack, | |
1020 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1021 | preempt_enable_no_resched(); |
1da177e4 LT |
1022 | return 1; |
1023 | } | |
1024 | return 0; | |
1025 | } | |
ba8af12f | 1026 | |
6772926b | 1027 | int __init arch_init_kprobes(void) |
ba8af12f | 1028 | { |
da07ab03 | 1029 | return 0; |
ba8af12f | 1030 | } |
bf8f6e5b AM |
1031 | |
1032 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1033 | { | |
bf8f6e5b AM |
1034 | return 0; |
1035 | } |