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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> | |
3f33ab1c | 33 | * Added function return probes functionality |
d6be29b8 | 34 | * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added |
3f33ab1c | 35 | * kprobe-booster and kretprobe-booster for i386. |
da07ab03 | 36 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster |
3f33ab1c | 37 | * and kretprobe-booster for x86-64 |
d6be29b8 | 38 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven |
3f33ab1c MH |
39 | * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> |
40 | * unified x86 kprobes code. | |
1da177e4 | 41 | */ |
1da177e4 LT |
42 | #include <linux/kprobes.h> |
43 | #include <linux/ptrace.h> | |
1da177e4 LT |
44 | #include <linux/string.h> |
45 | #include <linux/slab.h> | |
b506a9d0 | 46 | #include <linux/hardirq.h> |
1da177e4 | 47 | #include <linux/preempt.h> |
c28f8966 | 48 | #include <linux/module.h> |
1eeb66a1 | 49 | #include <linux/kdebug.h> |
b46b3d70 | 50 | #include <linux/kallsyms.h> |
c0f7ac3a | 51 | #include <linux/ftrace.h> |
9ec4b1f3 | 52 | |
8533bbe9 MH |
53 | #include <asm/cacheflush.h> |
54 | #include <asm/desc.h> | |
1da177e4 | 55 | #include <asm/pgtable.h> |
c28f8966 | 56 | #include <asm/uaccess.h> |
19d36ccd | 57 | #include <asm/alternative.h> |
b46b3d70 | 58 | #include <asm/insn.h> |
62edab90 | 59 | #include <asm/debugreg.h> |
1da177e4 | 60 | |
f684199f | 61 | #include "common.h" |
3f33ab1c | 62 | |
1da177e4 LT |
63 | void jprobe_return_end(void); |
64 | ||
e7a510f9 AM |
65 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
66 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 67 | |
98272ed0 | 68 | #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) |
8533bbe9 MH |
69 | |
70 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
71 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
72 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
73 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
74 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
75 | << (row % 32)) | |
76 | /* | |
77 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
78 | * Groups, and some special opcodes can not boost. | |
7115e3fc LT |
79 | * This is non-const and volatile to keep gcc from statically |
80 | * optimizing it out, as variable_test_bit makes gcc think only | |
f684199f | 81 | * *(unsigned long*) is used. |
8533bbe9 | 82 | */ |
7115e3fc | 83 | static volatile u32 twobyte_is_boostable[256 / 32] = { |
8533bbe9 MH |
84 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
85 | /* ---------------------------------------------- */ | |
86 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
87 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 10 */ | |
88 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ | |
89 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
90 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
91 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
92 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
93 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
94 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
95 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
96 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
97 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
98 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
99 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
100 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
101 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
102 | /* ----------------------------------------------- */ | |
103 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
104 | }; | |
8533bbe9 MH |
105 | #undef W |
106 | ||
f438d914 MH |
107 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
108 | {"__switch_to", }, /* This function switches only current task, but | |
109 | doesn't switch kernel stack.*/ | |
110 | {NULL, NULL} /* Terminator */ | |
111 | }; | |
3f33ab1c | 112 | |
f438d914 MH |
113 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); |
114 | ||
c0f7ac3a | 115 | static void __kprobes __synthesize_relative_insn(void *from, void *to, u8 op) |
aa470140 | 116 | { |
c0f7ac3a MH |
117 | struct __arch_relative_insn { |
118 | u8 op; | |
aa470140 | 119 | s32 raddr; |
f684199f | 120 | } __packed *insn; |
c0f7ac3a MH |
121 | |
122 | insn = (struct __arch_relative_insn *)from; | |
123 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
124 | insn->op = op; | |
125 | } | |
126 | ||
127 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
3f33ab1c | 128 | void __kprobes synthesize_reljump(void *from, void *to) |
c0f7ac3a MH |
129 | { |
130 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 MH |
131 | } |
132 | ||
3f33ab1c MH |
133 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ |
134 | void __kprobes synthesize_relcall(void *from, void *to) | |
135 | { | |
136 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
137 | } | |
138 | ||
9930927f | 139 | /* |
567a9fd8 | 140 | * Skip the prefixes of the instruction. |
9930927f | 141 | */ |
567a9fd8 | 142 | static kprobe_opcode_t *__kprobes skip_prefixes(kprobe_opcode_t *insn) |
9930927f | 143 | { |
567a9fd8 MH |
144 | insn_attr_t attr; |
145 | ||
146 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
147 | while (inat_is_legacy_prefix(attr)) { | |
148 | insn++; | |
149 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
150 | } | |
9930927f | 151 | #ifdef CONFIG_X86_64 |
567a9fd8 MH |
152 | if (inat_is_rex_prefix(attr)) |
153 | insn++; | |
9930927f | 154 | #endif |
567a9fd8 | 155 | return insn; |
9930927f HH |
156 | } |
157 | ||
aa470140 | 158 | /* |
d6be29b8 MH |
159 | * Returns non-zero if opcode is boostable. |
160 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 161 | */ |
3f33ab1c | 162 | int __kprobes can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 163 | { |
aa470140 MH |
164 | kprobe_opcode_t opcode; |
165 | kprobe_opcode_t *orig_opcodes = opcodes; | |
166 | ||
cde5edbd | 167 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
168 | return 0; /* Page fault may occur on this address. */ |
169 | ||
aa470140 MH |
170 | retry: |
171 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
172 | return 0; | |
173 | opcode = *(opcodes++); | |
174 | ||
175 | /* 2nd-byte opcode */ | |
176 | if (opcode == 0x0f) { | |
177 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
178 | return 0; | |
8533bbe9 MH |
179 | return test_bit(*opcodes, |
180 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
181 | } |
182 | ||
183 | switch (opcode & 0xf0) { | |
d6be29b8 | 184 | #ifdef CONFIG_X86_64 |
aa470140 MH |
185 | case 0x40: |
186 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 187 | #endif |
aa470140 MH |
188 | case 0x60: |
189 | if (0x63 < opcode && opcode < 0x67) | |
190 | goto retry; /* prefixes */ | |
191 | /* can't boost Address-size override and bound */ | |
192 | return (opcode != 0x62 && opcode != 0x67); | |
193 | case 0x70: | |
194 | return 0; /* can't boost conditional jump */ | |
195 | case 0xc0: | |
196 | /* can't boost software-interruptions */ | |
197 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
198 | case 0xd0: | |
199 | /* can boost AA* and XLAT */ | |
200 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
201 | case 0xe0: | |
202 | /* can boost in/out and absolute jmps */ | |
203 | return ((opcode & 0x04) || opcode == 0xea); | |
204 | case 0xf0: | |
205 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
206 | goto retry; /* lock/rep(ne) prefix */ | |
207 | /* clear and set flags are boostable */ | |
208 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
209 | default: | |
210 | /* segment override prefixes are boostable */ | |
211 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
212 | goto retry; /* prefixes */ | |
213 | /* CS override prefix and call are not boostable */ | |
214 | return (opcode != 0x2e && opcode != 0x9a); | |
215 | } | |
216 | } | |
217 | ||
3f33ab1c MH |
218 | static unsigned long |
219 | __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) | |
b46b3d70 MH |
220 | { |
221 | struct kprobe *kp; | |
86b4ce31 | 222 | |
b46b3d70 | 223 | kp = get_kprobe((void *)addr); |
86b4ce31 | 224 | /* There is no probe, return original address */ |
b46b3d70 | 225 | if (!kp) |
86b4ce31 | 226 | return addr; |
b46b3d70 MH |
227 | |
228 | /* | |
229 | * Basically, kp->ainsn.insn has an original instruction. | |
230 | * However, RIP-relative instruction can not do single-stepping | |
c0f7ac3a | 231 | * at different place, __copy_instruction() tweaks the displacement of |
b46b3d70 MH |
232 | * that instruction. In that case, we can't recover the instruction |
233 | * from the kp->ainsn.insn. | |
234 | * | |
235 | * On the other hand, kp->opcode has a copy of the first byte of | |
236 | * the probed instruction, which is overwritten by int3. And | |
237 | * the instruction at kp->addr is not modified by kprobes except | |
238 | * for the first byte, we can recover the original instruction | |
239 | * from it and kp->opcode. | |
240 | */ | |
241 | memcpy(buf, kp->addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); | |
242 | buf[0] = kp->opcode; | |
86b4ce31 MH |
243 | return (unsigned long)buf; |
244 | } | |
245 | ||
86b4ce31 MH |
246 | /* |
247 | * Recover the probed instruction at addr for further analysis. | |
248 | * Caller must lock kprobes by kprobe_mutex, or disable preemption | |
249 | * for preventing to release referencing kprobes. | |
250 | */ | |
3f33ab1c | 251 | unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) |
86b4ce31 MH |
252 | { |
253 | unsigned long __addr; | |
254 | ||
255 | __addr = __recover_optprobed_insn(buf, addr); | |
256 | if (__addr != addr) | |
257 | return __addr; | |
258 | ||
259 | return __recover_probed_insn(buf, addr); | |
b46b3d70 MH |
260 | } |
261 | ||
b46b3d70 MH |
262 | /* Check if paddr is at an instruction boundary */ |
263 | static int __kprobes can_probe(unsigned long paddr) | |
264 | { | |
86b4ce31 | 265 | unsigned long addr, __addr, offset = 0; |
b46b3d70 MH |
266 | struct insn insn; |
267 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
268 | ||
6abded71 | 269 | if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) |
b46b3d70 MH |
270 | return 0; |
271 | ||
272 | /* Decode instructions */ | |
273 | addr = paddr - offset; | |
274 | while (addr < paddr) { | |
b46b3d70 MH |
275 | /* |
276 | * Check if the instruction has been modified by another | |
277 | * kprobe, in which case we replace the breakpoint by the | |
278 | * original instruction in our buffer. | |
86b4ce31 MH |
279 | * Also, jump optimization will change the breakpoint to |
280 | * relative-jump. Since the relative-jump itself is | |
281 | * normally used, we just go through if there is no kprobe. | |
b46b3d70 | 282 | */ |
86b4ce31 MH |
283 | __addr = recover_probed_instruction(buf, addr); |
284 | kernel_insn_init(&insn, (void *)__addr); | |
b46b3d70 | 285 | insn_get_length(&insn); |
86b4ce31 MH |
286 | |
287 | /* | |
288 | * Another debugging subsystem might insert this breakpoint. | |
289 | * In that case, we can't recover it. | |
290 | */ | |
291 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) | |
292 | return 0; | |
b46b3d70 MH |
293 | addr += insn.length; |
294 | } | |
295 | ||
296 | return (addr == paddr); | |
297 | } | |
298 | ||
1da177e4 | 299 | /* |
d6be29b8 | 300 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 301 | */ |
8645419c | 302 | static int __kprobes is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 | 303 | { |
567a9fd8 MH |
304 | /* Skip prefixes */ |
305 | insn = skip_prefixes(insn); | |
306 | ||
1da177e4 LT |
307 | switch (*insn) { |
308 | case 0xfa: /* cli */ | |
309 | case 0xfb: /* sti */ | |
310 | case 0xcf: /* iret/iretd */ | |
311 | case 0x9d: /* popf/popfd */ | |
312 | return 1; | |
313 | } | |
9930927f | 314 | |
1da177e4 LT |
315 | return 0; |
316 | } | |
317 | ||
318 | /* | |
c0f7ac3a MH |
319 | * Copy an instruction and adjust the displacement if the instruction |
320 | * uses the %rip-relative addressing mode. | |
aa470140 | 321 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 322 | * If not, return null. |
31f80e45 | 323 | * Only applicable to 64-bit x86. |
1da177e4 | 324 | */ |
3f33ab1c | 325 | int __kprobes __copy_instruction(u8 *dest, u8 *src) |
1da177e4 | 326 | { |
89ae465b | 327 | struct insn insn; |
c0f7ac3a | 328 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
86b4ce31 | 329 | |
46484688 | 330 | kernel_insn_init(&insn, (void *)recover_probed_instruction(buf, (unsigned long)src)); |
c0f7ac3a | 331 | insn_get_length(&insn); |
86b4ce31 | 332 | /* Another subsystem puts a breakpoint, failed to recover */ |
46484688 | 333 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) |
86b4ce31 | 334 | return 0; |
c0f7ac3a MH |
335 | memcpy(dest, insn.kaddr, insn.length); |
336 | ||
337 | #ifdef CONFIG_X86_64 | |
89ae465b MH |
338 | if (insn_rip_relative(&insn)) { |
339 | s64 newdisp; | |
340 | u8 *disp; | |
c0f7ac3a | 341 | kernel_insn_init(&insn, dest); |
89ae465b MH |
342 | insn_get_displacement(&insn); |
343 | /* | |
344 | * The copied instruction uses the %rip-relative addressing | |
345 | * mode. Adjust the displacement for the difference between | |
346 | * the original location of this instruction and the location | |
347 | * of the copy that will actually be run. The tricky bit here | |
348 | * is making sure that the sign extension happens correctly in | |
349 | * this calculation, since we need a signed 32-bit result to | |
350 | * be sign-extended to 64 bits when it's added to the %rip | |
351 | * value and yield the same 64-bit result that the sign- | |
352 | * extension of the original signed 32-bit displacement would | |
353 | * have given. | |
354 | */ | |
46484688 | 355 | newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest; |
89ae465b | 356 | BUG_ON((s64) (s32) newdisp != newdisp); /* Sanity check. */ |
c0f7ac3a | 357 | disp = (u8 *) dest + insn_offset_displacement(&insn); |
89ae465b | 358 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 359 | } |
d6be29b8 | 360 | #endif |
c0f7ac3a | 361 | return insn.length; |
31f80e45 | 362 | } |
1da177e4 | 363 | |
f709b122 | 364 | static void __kprobes arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 365 | { |
46484688 MH |
366 | /* Copy an instruction with recovering if other optprobe modifies it.*/ |
367 | __copy_instruction(p->ainsn.insn, p->addr); | |
368 | ||
c0f7ac3a | 369 | /* |
46484688 MH |
370 | * __copy_instruction can modify the displacement of the instruction, |
371 | * but it doesn't affect boostable check. | |
c0f7ac3a | 372 | */ |
46484688 | 373 | if (can_boost(p->ainsn.insn)) |
aa470140 | 374 | p->ainsn.boostable = 0; |
8533bbe9 | 375 | else |
aa470140 | 376 | p->ainsn.boostable = -1; |
8533bbe9 | 377 | |
9a556ab9 MH |
378 | /* Check whether the instruction modifies Interrupt Flag or not */ |
379 | p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); | |
380 | ||
46484688 MH |
381 | /* Also, displacement change doesn't affect the first byte */ |
382 | p->opcode = p->ainsn.insn[0]; | |
1da177e4 LT |
383 | } |
384 | ||
8533bbe9 MH |
385 | int __kprobes arch_prepare_kprobe(struct kprobe *p) |
386 | { | |
4554dbcb MH |
387 | if (alternatives_text_reserved(p->addr, p->addr)) |
388 | return -EINVAL; | |
389 | ||
b46b3d70 MH |
390 | if (!can_probe((unsigned long)p->addr)) |
391 | return -EILSEQ; | |
8533bbe9 MH |
392 | /* insn: must be on special executable page on x86. */ |
393 | p->ainsn.insn = get_insn_slot(); | |
394 | if (!p->ainsn.insn) | |
395 | return -ENOMEM; | |
396 | arch_copy_kprobe(p); | |
397 | return 0; | |
398 | } | |
399 | ||
0f2fbdcb | 400 | void __kprobes arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 401 | { |
19d36ccd | 402 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
403 | } |
404 | ||
0f2fbdcb | 405 | void __kprobes arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 406 | { |
19d36ccd | 407 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
408 | } |
409 | ||
0498b635 | 410 | void __kprobes arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 411 | { |
12941560 MH |
412 | if (p->ainsn.insn) { |
413 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
414 | p->ainsn.insn = NULL; | |
415 | } | |
1da177e4 LT |
416 | } |
417 | ||
3b60211c | 418 | static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 419 | { |
e7a510f9 AM |
420 | kcb->prev_kprobe.kp = kprobe_running(); |
421 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
422 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
423 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
424 | } |
425 | ||
3b60211c | 426 | static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
aa3d7e3d | 427 | { |
b76834bc | 428 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
e7a510f9 | 429 | kcb->kprobe_status = kcb->prev_kprobe.status; |
8533bbe9 MH |
430 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
431 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
432 | } |
433 | ||
3b60211c | 434 | static void __kprobes set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
e7a510f9 | 435 | struct kprobe_ctlblk *kcb) |
aa3d7e3d | 436 | { |
b76834bc | 437 | __this_cpu_write(current_kprobe, p); |
8533bbe9 | 438 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 439 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
9a556ab9 | 440 | if (p->ainsn.if_modifier) |
053de044 | 441 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
442 | } |
443 | ||
e7b5e11e | 444 | static void __kprobes clear_btf(void) |
1ecc798c | 445 | { |
ea8e61b7 PZ |
446 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
447 | unsigned long debugctl = get_debugctlmsr(); | |
448 | ||
449 | debugctl &= ~DEBUGCTLMSR_BTF; | |
450 | update_debugctlmsr(debugctl); | |
451 | } | |
1ecc798c RM |
452 | } |
453 | ||
e7b5e11e | 454 | static void __kprobes restore_btf(void) |
1ecc798c | 455 | { |
ea8e61b7 PZ |
456 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
457 | unsigned long debugctl = get_debugctlmsr(); | |
458 | ||
459 | debugctl |= DEBUGCTLMSR_BTF; | |
460 | update_debugctlmsr(debugctl); | |
461 | } | |
1ecc798c RM |
462 | } |
463 | ||
3f33ab1c MH |
464 | void __kprobes |
465 | arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) | |
73649dab | 466 | { |
8533bbe9 | 467 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 468 | |
4c4308cb | 469 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 470 | |
4c4308cb CH |
471 | /* Replace the return addr with trampoline addr */ |
472 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 473 | } |
f315decb | 474 | |
3f33ab1c MH |
475 | static void __kprobes |
476 | setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, int reenter) | |
f315decb | 477 | { |
c0f7ac3a MH |
478 | if (setup_detour_execution(p, regs, reenter)) |
479 | return; | |
480 | ||
615d0ebb | 481 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
482 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
483 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
484 | if (!reenter) |
485 | reset_current_kprobe(); | |
486 | /* | |
487 | * Reentering boosted probe doesn't reset current_kprobe, | |
488 | * nor set current_kprobe, because it doesn't use single | |
489 | * stepping. | |
490 | */ | |
f315decb AS |
491 | regs->ip = (unsigned long)p->ainsn.insn; |
492 | preempt_enable_no_resched(); | |
493 | return; | |
494 | } | |
495 | #endif | |
0f94eb63 MH |
496 | if (reenter) { |
497 | save_previous_kprobe(kcb); | |
498 | set_current_kprobe(p, regs, kcb); | |
499 | kcb->kprobe_status = KPROBE_REENTER; | |
500 | } else | |
501 | kcb->kprobe_status = KPROBE_HIT_SS; | |
502 | /* Prepare real single stepping */ | |
503 | clear_btf(); | |
504 | regs->flags |= X86_EFLAGS_TF; | |
505 | regs->flags &= ~X86_EFLAGS_IF; | |
506 | /* single step inline if the instruction is an int3 */ | |
507 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
508 | regs->ip = (unsigned long)p->addr; | |
509 | else | |
510 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb AS |
511 | } |
512 | ||
40102d4a HH |
513 | /* |
514 | * We have reentered the kprobe_handler(), since another probe was hit while | |
515 | * within the handler. We save the original kprobes variables and just single | |
516 | * step on the instruction of the new probe without calling any user handlers. | |
517 | */ | |
3f33ab1c MH |
518 | static int __kprobes |
519 | reenter_kprobe(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
40102d4a | 520 | { |
f315decb AS |
521 | switch (kcb->kprobe_status) { |
522 | case KPROBE_HIT_SSDONE: | |
f315decb | 523 | case KPROBE_HIT_ACTIVE: |
fb8830e7 | 524 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 525 | setup_singlestep(p, regs, kcb, 1); |
f315decb AS |
526 | break; |
527 | case KPROBE_HIT_SS: | |
e9afe9e1 MH |
528 | /* A probe has been hit in the codepath leading up to, or just |
529 | * after, single-stepping of a probed instruction. This entire | |
530 | * codepath should strictly reside in .kprobes.text section. | |
531 | * Raise a BUG or we'll continue in an endless reentering loop | |
532 | * and eventually a stack overflow. | |
533 | */ | |
534 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
535 | p->addr); | |
536 | dump_kprobe(p); | |
537 | BUG(); | |
f315decb AS |
538 | default: |
539 | /* impossible cases */ | |
540 | WARN_ON(1); | |
fb8830e7 | 541 | return 0; |
59e87cdc | 542 | } |
f315decb | 543 | |
59e87cdc | 544 | return 1; |
40102d4a | 545 | } |
73649dab | 546 | |
8533bbe9 MH |
547 | /* |
548 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 549 | * remain disabled throughout this function. |
8533bbe9 MH |
550 | */ |
551 | static int __kprobes kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 552 | { |
8533bbe9 | 553 | kprobe_opcode_t *addr; |
f315decb | 554 | struct kprobe *p; |
d217d545 AM |
555 | struct kprobe_ctlblk *kcb; |
556 | ||
8533bbe9 | 557 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
558 | /* |
559 | * We don't want to be preempted for the entire | |
f315decb AS |
560 | * duration of kprobe processing. We conditionally |
561 | * re-enable preemption at the end of this function, | |
562 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
563 | */ |
564 | preempt_disable(); | |
1da177e4 | 565 | |
f315decb | 566 | kcb = get_kprobe_ctlblk(); |
b9760156 | 567 | p = get_kprobe(addr); |
f315decb | 568 | |
b9760156 | 569 | if (p) { |
b9760156 | 570 | if (kprobe_running()) { |
f315decb AS |
571 | if (reenter_kprobe(p, regs, kcb)) |
572 | return 1; | |
1da177e4 | 573 | } else { |
b9760156 HH |
574 | set_current_kprobe(p, regs, kcb); |
575 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 576 | |
1da177e4 | 577 | /* |
f315decb AS |
578 | * If we have no pre-handler or it returned 0, we |
579 | * continue with normal processing. If we have a | |
580 | * pre-handler and it returned non-zero, it prepped | |
581 | * for calling the break_handler below on re-entry | |
582 | * for jprobe processing, so get out doing nothing | |
583 | * more here. | |
1da177e4 | 584 | */ |
f315decb | 585 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 586 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 587 | return 1; |
b9760156 | 588 | } |
829e9245 MH |
589 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
590 | /* | |
591 | * The breakpoint instruction was removed right | |
592 | * after we hit it. Another cpu has removed | |
593 | * either a probepoint or a debugger breakpoint | |
594 | * at this address. In either case, no further | |
595 | * handling of this interrupt is appropriate. | |
596 | * Back up over the (now missing) int3 and run | |
597 | * the original instruction. | |
598 | */ | |
599 | regs->ip = (unsigned long)addr; | |
600 | preempt_enable_no_resched(); | |
601 | return 1; | |
f315decb | 602 | } else if (kprobe_running()) { |
b76834bc | 603 | p = __this_cpu_read(current_kprobe); |
f315decb | 604 | if (p->break_handler && p->break_handler(p, regs)) { |
e7dbfe34 MH |
605 | if (!skip_singlestep(p, regs, kcb)) |
606 | setup_singlestep(p, regs, kcb, 0); | |
f315decb | 607 | return 1; |
1da177e4 | 608 | } |
f315decb | 609 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 610 | |
d217d545 | 611 | preempt_enable_no_resched(); |
f315decb | 612 | return 0; |
1da177e4 LT |
613 | } |
614 | ||
73649dab | 615 | /* |
da07ab03 MH |
616 | * When a retprobed function returns, this code saves registers and |
617 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 618 | */ |
f1452d42 | 619 | static void __used __kprobes kretprobe_trampoline_holder(void) |
1017579a | 620 | { |
d6be29b8 MH |
621 | asm volatile ( |
622 | ".global kretprobe_trampoline\n" | |
da07ab03 | 623 | "kretprobe_trampoline: \n" |
d6be29b8 | 624 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
625 | /* We don't bother saving the ss register */ |
626 | " pushq %rsp\n" | |
627 | " pushfq\n" | |
f007ea26 | 628 | SAVE_REGS_STRING |
da07ab03 MH |
629 | " movq %rsp, %rdi\n" |
630 | " call trampoline_handler\n" | |
631 | /* Replace saved sp with true return address. */ | |
632 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 633 | RESTORE_REGS_STRING |
da07ab03 | 634 | " popfq\n" |
d6be29b8 MH |
635 | #else |
636 | " pushf\n" | |
f007ea26 | 637 | SAVE_REGS_STRING |
d6be29b8 MH |
638 | " movl %esp, %eax\n" |
639 | " call trampoline_handler\n" | |
640 | /* Move flags to cs */ | |
fee039a1 MH |
641 | " movl 56(%esp), %edx\n" |
642 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 643 | /* Replace saved flags with true return address. */ |
fee039a1 | 644 | " movl %eax, 56(%esp)\n" |
f007ea26 | 645 | RESTORE_REGS_STRING |
d6be29b8 MH |
646 | " popf\n" |
647 | #endif | |
da07ab03 | 648 | " ret\n"); |
1017579a | 649 | } |
73649dab RL |
650 | |
651 | /* | |
da07ab03 | 652 | * Called from kretprobe_trampoline |
73649dab | 653 | */ |
f1452d42 | 654 | static __used __kprobes void *trampoline_handler(struct pt_regs *regs) |
73649dab | 655 | { |
62c27be0 | 656 | struct kretprobe_instance *ri = NULL; |
99219a3f | 657 | struct hlist_head *head, empty_rp; |
b67bfe0d | 658 | struct hlist_node *tmp; |
991a51d8 | 659 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 660 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
737480a0 | 661 | kprobe_opcode_t *correct_ret_addr = NULL; |
73649dab | 662 | |
99219a3f | 663 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 664 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 665 | /* fixup registers */ |
d6be29b8 | 666 | #ifdef CONFIG_X86_64 |
da07ab03 | 667 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
668 | #else |
669 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 670 | regs->gs = 0; |
d6be29b8 | 671 | #endif |
da07ab03 | 672 | regs->ip = trampoline_address; |
8533bbe9 | 673 | regs->orig_ax = ~0UL; |
73649dab | 674 | |
ba8af12f RL |
675 | /* |
676 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 677 | * task either because multiple functions in the call path have |
025dfdaf | 678 | * return probes installed on them, and/or more than one |
ba8af12f RL |
679 | * return probe was registered for a target function. |
680 | * | |
681 | * We can handle this because: | |
8533bbe9 | 682 | * - instances are always pushed into the head of the list |
ba8af12f | 683 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
684 | * function, the (chronologically) first instance's ret_addr |
685 | * will be the real return address, and all the rest will | |
686 | * point to kretprobe_trampoline. | |
ba8af12f | 687 | */ |
b67bfe0d | 688 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
62c27be0 | 689 | if (ri->task != current) |
ba8af12f | 690 | /* another task is sharing our hash bucket */ |
62c27be0 | 691 | continue; |
ba8af12f | 692 | |
737480a0 KS |
693 | orig_ret_address = (unsigned long)ri->ret_addr; |
694 | ||
695 | if (orig_ret_address != trampoline_address) | |
696 | /* | |
697 | * This is the real return address. Any other | |
698 | * instances associated with this task are for | |
699 | * other calls deeper on the call stack | |
700 | */ | |
701 | break; | |
702 | } | |
703 | ||
704 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
705 | ||
706 | correct_ret_addr = ri->ret_addr; | |
b67bfe0d | 707 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
737480a0 KS |
708 | if (ri->task != current) |
709 | /* another task is sharing our hash bucket */ | |
710 | continue; | |
711 | ||
712 | orig_ret_address = (unsigned long)ri->ret_addr; | |
da07ab03 | 713 | if (ri->rp && ri->rp->handler) { |
b76834bc | 714 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
da07ab03 | 715 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
737480a0 | 716 | ri->ret_addr = correct_ret_addr; |
ba8af12f | 717 | ri->rp->handler(ri, regs); |
b76834bc | 718 | __this_cpu_write(current_kprobe, NULL); |
da07ab03 | 719 | } |
ba8af12f | 720 | |
99219a3f | 721 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
722 | |
723 | if (orig_ret_address != trampoline_address) | |
724 | /* | |
725 | * This is the real return address. Any other | |
726 | * instances associated with this task are for | |
727 | * other calls deeper on the call stack | |
728 | */ | |
729 | break; | |
73649dab | 730 | } |
ba8af12f | 731 | |
ef53d9c5 | 732 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 733 | |
b67bfe0d | 734 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 735 | hlist_del(&ri->hlist); |
736 | kfree(ri); | |
737 | } | |
da07ab03 | 738 | return (void *)orig_ret_address; |
73649dab RL |
739 | } |
740 | ||
1da177e4 LT |
741 | /* |
742 | * Called after single-stepping. p->addr is the address of the | |
743 | * instruction whose first byte has been replaced by the "int 3" | |
744 | * instruction. To avoid the SMP problems that can occur when we | |
745 | * temporarily put back the original opcode to single-step, we | |
746 | * single-stepped a copy of the instruction. The address of this | |
747 | * copy is p->ainsn.insn. | |
748 | * | |
749 | * This function prepares to return from the post-single-step | |
750 | * interrupt. We have to fix up the stack as follows: | |
751 | * | |
752 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 753 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
754 | * it relative to the original instruction. |
755 | * | |
756 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 757 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
758 | * |
759 | * 2) If the single-stepped instruction was a call, the return address | |
760 | * that is atop the stack is the address following the copied instruction. | |
761 | * We need to make it the address following the original instruction. | |
aa470140 MH |
762 | * |
763 | * If this is the first time we've single-stepped the instruction at | |
764 | * this probepoint, and the instruction is boostable, boost it: add a | |
765 | * jump instruction after the copied instruction, that jumps to the next | |
766 | * instruction after the probepoint. | |
1da177e4 | 767 | */ |
3f33ab1c MH |
768 | static void __kprobes |
769 | resume_execution(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) | |
1da177e4 | 770 | { |
8533bbe9 MH |
771 | unsigned long *tos = stack_addr(regs); |
772 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
773 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
774 | kprobe_opcode_t *insn = p->ainsn.insn; |
775 | ||
567a9fd8 MH |
776 | /* Skip prefixes */ |
777 | insn = skip_prefixes(insn); | |
1da177e4 | 778 | |
053de044 | 779 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 780 | switch (*insn) { |
0b0122fa | 781 | case 0x9c: /* pushfl */ |
053de044 | 782 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 783 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 784 | break; |
0b0122fa MH |
785 | case 0xc2: /* iret/ret/lret */ |
786 | case 0xc3: | |
0b9e2cac | 787 | case 0xca: |
0b0122fa MH |
788 | case 0xcb: |
789 | case 0xcf: | |
790 | case 0xea: /* jmp absolute -- ip is correct */ | |
791 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 792 | p->ainsn.boostable = 1; |
0b0122fa MH |
793 | goto no_change; |
794 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 795 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 796 | break; |
e7b5e11e | 797 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
798 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
799 | *tos = orig_ip + (*tos - copy_ip); | |
800 | goto no_change; | |
801 | #endif | |
1da177e4 | 802 | case 0xff: |
dc49e344 | 803 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
804 | /* |
805 | * call absolute, indirect | |
806 | * Fix return addr; ip is correct. | |
807 | * But this is not boostable | |
808 | */ | |
809 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 810 | goto no_change; |
8533bbe9 MH |
811 | } else if (((insn[1] & 0x31) == 0x20) || |
812 | ((insn[1] & 0x31) == 0x21)) { | |
813 | /* | |
814 | * jmp near and far, absolute indirect | |
815 | * ip is correct. And this is boostable | |
816 | */ | |
aa470140 | 817 | p->ainsn.boostable = 1; |
0b0122fa | 818 | goto no_change; |
1da177e4 | 819 | } |
1da177e4 LT |
820 | default: |
821 | break; | |
822 | } | |
823 | ||
aa470140 | 824 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
825 | if ((regs->ip > copy_ip) && |
826 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
827 | /* |
828 | * These instructions can be executed directly if it | |
829 | * jumps back to correct address. | |
830 | */ | |
c0f7ac3a MH |
831 | synthesize_reljump((void *)regs->ip, |
832 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
833 | p->ainsn.boostable = 1; |
834 | } else { | |
835 | p->ainsn.boostable = -1; | |
836 | } | |
837 | } | |
838 | ||
8533bbe9 | 839 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 840 | |
0b0122fa | 841 | no_change: |
1ecc798c | 842 | restore_btf(); |
1da177e4 LT |
843 | } |
844 | ||
8533bbe9 MH |
845 | /* |
846 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 847 | * remain disabled throughout this function. |
8533bbe9 MH |
848 | */ |
849 | static int __kprobes post_kprobe_handler(struct pt_regs *regs) | |
1da177e4 | 850 | { |
e7a510f9 AM |
851 | struct kprobe *cur = kprobe_running(); |
852 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
853 | ||
854 | if (!cur) | |
1da177e4 LT |
855 | return 0; |
856 | ||
acb5b8a2 YL |
857 | resume_execution(cur, regs, kcb); |
858 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 859 | |
e7a510f9 AM |
860 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
861 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
862 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 863 | } |
1da177e4 | 864 | |
8533bbe9 | 865 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
866 | if (kcb->kprobe_status == KPROBE_REENTER) { |
867 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 868 | goto out; |
aa3d7e3d | 869 | } |
e7a510f9 | 870 | reset_current_kprobe(); |
aa3d7e3d | 871 | out: |
1da177e4 LT |
872 | preempt_enable_no_resched(); |
873 | ||
874 | /* | |
65ea5b03 | 875 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
876 | * will have TF set, in which case, continue the remaining processing |
877 | * of do_debug, as if this is not a probe hit. | |
878 | */ | |
053de044 | 879 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
880 | return 0; |
881 | ||
882 | return 1; | |
883 | } | |
884 | ||
0f2fbdcb | 885 | int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 886 | { |
e7a510f9 AM |
887 | struct kprobe *cur = kprobe_running(); |
888 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
889 | ||
d6be29b8 | 890 | switch (kcb->kprobe_status) { |
c28f8966 PP |
891 | case KPROBE_HIT_SS: |
892 | case KPROBE_REENTER: | |
893 | /* | |
894 | * We are here because the instruction being single | |
895 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 896 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
897 | * and allow the page fault handler to continue as a |
898 | * normal page fault. | |
899 | */ | |
65ea5b03 | 900 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 901 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
902 | if (kcb->kprobe_status == KPROBE_REENTER) |
903 | restore_previous_kprobe(kcb); | |
904 | else | |
905 | reset_current_kprobe(); | |
1da177e4 | 906 | preempt_enable_no_resched(); |
c28f8966 PP |
907 | break; |
908 | case KPROBE_HIT_ACTIVE: | |
909 | case KPROBE_HIT_SSDONE: | |
910 | /* | |
911 | * We increment the nmissed count for accounting, | |
8533bbe9 | 912 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
913 | * these specific fault cases. |
914 | */ | |
915 | kprobes_inc_nmissed_count(cur); | |
916 | ||
917 | /* | |
918 | * We come here because instructions in the pre/post | |
919 | * handler caused the page_fault, this could happen | |
920 | * if handler tries to access user space by | |
921 | * copy_from_user(), get_user() etc. Let the | |
922 | * user-specified handler try to fix it first. | |
923 | */ | |
924 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
925 | return 1; | |
926 | ||
927 | /* | |
928 | * In case the user-specified fault handler returned | |
929 | * zero, try to fix up. | |
930 | */ | |
d6be29b8 MH |
931 | if (fixup_exception(regs)) |
932 | return 1; | |
6d48583b | 933 | |
c28f8966 | 934 | /* |
8533bbe9 | 935 | * fixup routine could not handle it, |
c28f8966 PP |
936 | * Let do_page_fault() fix it. |
937 | */ | |
938 | break; | |
939 | default: | |
940 | break; | |
1da177e4 LT |
941 | } |
942 | return 0; | |
943 | } | |
944 | ||
945 | /* | |
946 | * Wrapper routine for handling exceptions. | |
947 | */ | |
3f33ab1c MH |
948 | int __kprobes |
949 | kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, void *data) | |
1da177e4 | 950 | { |
ade1af77 | 951 | struct die_args *args = data; |
66ff2d06 AM |
952 | int ret = NOTIFY_DONE; |
953 | ||
8533bbe9 | 954 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 955 | return ret; |
956 | ||
1da177e4 LT |
957 | switch (val) { |
958 | case DIE_INT3: | |
959 | if (kprobe_handler(args->regs)) | |
66ff2d06 | 960 | ret = NOTIFY_STOP; |
1da177e4 LT |
961 | break; |
962 | case DIE_DEBUG: | |
62edab90 P |
963 | if (post_kprobe_handler(args->regs)) { |
964 | /* | |
965 | * Reset the BS bit in dr6 (pointed by args->err) to | |
966 | * denote completion of processing | |
967 | */ | |
968 | (*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP; | |
66ff2d06 | 969 | ret = NOTIFY_STOP; |
62edab90 | 970 | } |
1da177e4 LT |
971 | break; |
972 | case DIE_GPF: | |
b506a9d0 QB |
973 | /* |
974 | * To be potentially processing a kprobe fault and to | |
975 | * trust the result from kprobe_running(), we have | |
976 | * be non-preemptible. | |
977 | */ | |
978 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 979 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 980 | ret = NOTIFY_STOP; |
1da177e4 LT |
981 | break; |
982 | default: | |
983 | break; | |
984 | } | |
66ff2d06 | 985 | return ret; |
1da177e4 LT |
986 | } |
987 | ||
0f2fbdcb | 988 | int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
989 | { |
990 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
991 | unsigned long addr; | |
e7a510f9 | 992 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 993 | |
e7a510f9 | 994 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
995 | kcb->jprobe_saved_sp = stack_addr(regs); |
996 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
997 | ||
1da177e4 LT |
998 | /* |
999 | * As Linus pointed out, gcc assumes that the callee | |
1000 | * owns the argument space and could overwrite it, e.g. | |
1001 | * tailcall optimization. So, to be absolutely safe | |
1002 | * we also save and restore enough stack bytes to cover | |
1003 | * the argument area. | |
1004 | */ | |
e7a510f9 | 1005 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1006 | MIN_STACK_SIZE(addr)); |
053de044 | 1007 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1008 | trace_hardirqs_off(); |
65ea5b03 | 1009 | regs->ip = (unsigned long)(jp->entry); |
1da177e4 LT |
1010 | return 1; |
1011 | } | |
1012 | ||
0f2fbdcb | 1013 | void __kprobes jprobe_return(void) |
1da177e4 | 1014 | { |
e7a510f9 AM |
1015 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1016 | ||
d6be29b8 MH |
1017 | asm volatile ( |
1018 | #ifdef CONFIG_X86_64 | |
1019 | " xchg %%rbx,%%rsp \n" | |
1020 | #else | |
1021 | " xchgl %%ebx,%%esp \n" | |
1022 | #endif | |
1023 | " int3 \n" | |
1024 | " .globl jprobe_return_end\n" | |
1025 | " jprobe_return_end: \n" | |
1026 | " nop \n"::"b" | |
1027 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 LT |
1028 | } |
1029 | ||
0f2fbdcb | 1030 | int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1031 | { |
e7a510f9 | 1032 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1033 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 LT |
1034 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
1035 | ||
d6be29b8 MH |
1036 | if ((addr > (u8 *) jprobe_return) && |
1037 | (addr < (u8 *) jprobe_return_end)) { | |
8533bbe9 | 1038 | if (stack_addr(regs) != kcb->jprobe_saved_sp) { |
29b6cd79 | 1039 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1040 | printk(KERN_ERR |
1041 | "current sp %p does not match saved sp %p\n", | |
8533bbe9 | 1042 | stack_addr(regs), kcb->jprobe_saved_sp); |
d6be29b8 | 1043 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
57da8b96 | 1044 | show_regs(saved_regs); |
d6be29b8 | 1045 | printk(KERN_ERR "Current registers\n"); |
57da8b96 | 1046 | show_regs(regs); |
1da177e4 LT |
1047 | BUG(); |
1048 | } | |
e7a510f9 | 1049 | *regs = kcb->jprobe_saved_regs; |
8533bbe9 MH |
1050 | memcpy((kprobe_opcode_t *)(kcb->jprobe_saved_sp), |
1051 | kcb->jprobes_stack, | |
1052 | MIN_STACK_SIZE(kcb->jprobe_saved_sp)); | |
d217d545 | 1053 | preempt_enable_no_resched(); |
1da177e4 LT |
1054 | return 1; |
1055 | } | |
1056 | return 0; | |
1057 | } | |
ba8af12f | 1058 | |
6772926b | 1059 | int __init arch_init_kprobes(void) |
ba8af12f | 1060 | { |
3f33ab1c | 1061 | return arch_init_optprobes(); |
ba8af12f | 1062 | } |
bf8f6e5b AM |
1063 | |
1064 | int __kprobes arch_trampoline_kprobe(struct kprobe *p) | |
1065 | { | |
bf8f6e5b AM |
1066 | return 0; |
1067 | } |