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> | |
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> |
87aaff2a | 52 | #include <linux/frame.h> |
9ec4b1f3 | 53 | |
35de5b06 | 54 | #include <asm/text-patching.h> |
8533bbe9 MH |
55 | #include <asm/cacheflush.h> |
56 | #include <asm/desc.h> | |
1da177e4 | 57 | #include <asm/pgtable.h> |
c28f8966 | 58 | #include <asm/uaccess.h> |
19d36ccd | 59 | #include <asm/alternative.h> |
b46b3d70 | 60 | #include <asm/insn.h> |
62edab90 | 61 | #include <asm/debugreg.h> |
1da177e4 | 62 | |
f684199f | 63 | #include "common.h" |
3f33ab1c | 64 | |
1da177e4 LT |
65 | void jprobe_return_end(void); |
66 | ||
e7a510f9 AM |
67 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
68 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 69 | |
98272ed0 | 70 | #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) |
8533bbe9 MH |
71 | |
72 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
73 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
74 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
75 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
76 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
77 | << (row % 32)) | |
78 | /* | |
79 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
80 | * Groups, and some special opcodes can not boost. | |
7115e3fc LT |
81 | * This is non-const and volatile to keep gcc from statically |
82 | * optimizing it out, as variable_test_bit makes gcc think only | |
f684199f | 83 | * *(unsigned long*) is used. |
8533bbe9 | 84 | */ |
7115e3fc | 85 | static volatile u32 twobyte_is_boostable[256 / 32] = { |
8533bbe9 MH |
86 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
87 | /* ---------------------------------------------- */ | |
88 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
b7e37567 | 89 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */ |
8533bbe9 MH |
90 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ |
91 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
92 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
93 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
94 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
95 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
96 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
97 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
98 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
99 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
100 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
101 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
102 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
103 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
104 | /* ----------------------------------------------- */ | |
105 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
106 | }; | |
8533bbe9 MH |
107 | #undef W |
108 | ||
f438d914 MH |
109 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
110 | {"__switch_to", }, /* This function switches only current task, but | |
111 | doesn't switch kernel stack.*/ | |
112 | {NULL, NULL} /* Terminator */ | |
113 | }; | |
3f33ab1c | 114 | |
f438d914 MH |
115 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); |
116 | ||
9326638c MH |
117 | static nokprobe_inline void |
118 | __synthesize_relative_insn(void *from, void *to, u8 op) | |
aa470140 | 119 | { |
c0f7ac3a MH |
120 | struct __arch_relative_insn { |
121 | u8 op; | |
aa470140 | 122 | s32 raddr; |
f684199f | 123 | } __packed *insn; |
c0f7ac3a MH |
124 | |
125 | insn = (struct __arch_relative_insn *)from; | |
126 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
127 | insn->op = op; | |
128 | } | |
129 | ||
130 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
9326638c | 131 | void synthesize_reljump(void *from, void *to) |
c0f7ac3a MH |
132 | { |
133 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 | 134 | } |
9326638c | 135 | NOKPROBE_SYMBOL(synthesize_reljump); |
aa470140 | 136 | |
3f33ab1c | 137 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ |
9326638c | 138 | void synthesize_relcall(void *from, void *to) |
3f33ab1c MH |
139 | { |
140 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
141 | } | |
9326638c | 142 | NOKPROBE_SYMBOL(synthesize_relcall); |
3f33ab1c | 143 | |
9930927f | 144 | /* |
567a9fd8 | 145 | * Skip the prefixes of the instruction. |
9930927f | 146 | */ |
9326638c | 147 | static kprobe_opcode_t *skip_prefixes(kprobe_opcode_t *insn) |
9930927f | 148 | { |
567a9fd8 MH |
149 | insn_attr_t attr; |
150 | ||
151 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
152 | while (inat_is_legacy_prefix(attr)) { | |
153 | insn++; | |
154 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
155 | } | |
9930927f | 156 | #ifdef CONFIG_X86_64 |
567a9fd8 MH |
157 | if (inat_is_rex_prefix(attr)) |
158 | insn++; | |
9930927f | 159 | #endif |
567a9fd8 | 160 | return insn; |
9930927f | 161 | } |
9326638c | 162 | NOKPROBE_SYMBOL(skip_prefixes); |
9930927f | 163 | |
aa470140 | 164 | /* |
d6be29b8 MH |
165 | * Returns non-zero if opcode is boostable. |
166 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 167 | */ |
7ec8a97a | 168 | int can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 169 | { |
aa470140 MH |
170 | kprobe_opcode_t opcode; |
171 | kprobe_opcode_t *orig_opcodes = opcodes; | |
172 | ||
cde5edbd | 173 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
174 | return 0; /* Page fault may occur on this address. */ |
175 | ||
aa470140 MH |
176 | retry: |
177 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
178 | return 0; | |
179 | opcode = *(opcodes++); | |
180 | ||
181 | /* 2nd-byte opcode */ | |
182 | if (opcode == 0x0f) { | |
183 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
184 | return 0; | |
8533bbe9 MH |
185 | return test_bit(*opcodes, |
186 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
187 | } |
188 | ||
189 | switch (opcode & 0xf0) { | |
d6be29b8 | 190 | #ifdef CONFIG_X86_64 |
aa470140 MH |
191 | case 0x40: |
192 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 193 | #endif |
aa470140 MH |
194 | case 0x60: |
195 | if (0x63 < opcode && opcode < 0x67) | |
196 | goto retry; /* prefixes */ | |
197 | /* can't boost Address-size override and bound */ | |
198 | return (opcode != 0x62 && opcode != 0x67); | |
199 | case 0x70: | |
200 | return 0; /* can't boost conditional jump */ | |
201 | case 0xc0: | |
202 | /* can't boost software-interruptions */ | |
203 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
204 | case 0xd0: | |
205 | /* can boost AA* and XLAT */ | |
206 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
207 | case 0xe0: | |
208 | /* can boost in/out and absolute jmps */ | |
209 | return ((opcode & 0x04) || opcode == 0xea); | |
210 | case 0xf0: | |
211 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
212 | goto retry; /* lock/rep(ne) prefix */ | |
213 | /* clear and set flags are boostable */ | |
214 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
215 | default: | |
216 | /* segment override prefixes are boostable */ | |
217 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
218 | goto retry; /* prefixes */ | |
219 | /* CS override prefix and call are not boostable */ | |
220 | return (opcode != 0x2e && opcode != 0x9a); | |
221 | } | |
222 | } | |
223 | ||
3f33ab1c MH |
224 | static unsigned long |
225 | __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) | |
b46b3d70 MH |
226 | { |
227 | struct kprobe *kp; | |
650b7b23 | 228 | unsigned long faddr; |
86b4ce31 | 229 | |
b46b3d70 | 230 | kp = get_kprobe((void *)addr); |
650b7b23 | 231 | faddr = ftrace_location(addr); |
2a6730c8 PM |
232 | /* |
233 | * Addresses inside the ftrace location are refused by | |
234 | * arch_check_ftrace_location(). Something went terribly wrong | |
235 | * if such an address is checked here. | |
236 | */ | |
237 | if (WARN_ON(faddr && faddr != addr)) | |
238 | return 0UL; | |
650b7b23 PM |
239 | /* |
240 | * Use the current code if it is not modified by Kprobe | |
241 | * and it cannot be modified by ftrace. | |
242 | */ | |
243 | if (!kp && !faddr) | |
86b4ce31 | 244 | return addr; |
b46b3d70 MH |
245 | |
246 | /* | |
650b7b23 PM |
247 | * Basically, kp->ainsn.insn has an original instruction. |
248 | * However, RIP-relative instruction can not do single-stepping | |
249 | * at different place, __copy_instruction() tweaks the displacement of | |
250 | * that instruction. In that case, we can't recover the instruction | |
251 | * from the kp->ainsn.insn. | |
252 | * | |
253 | * On the other hand, in case on normal Kprobe, kp->opcode has a copy | |
254 | * of the first byte of the probed instruction, which is overwritten | |
255 | * by int3. And the instruction at kp->addr is not modified by kprobes | |
256 | * except for the first byte, we can recover the original instruction | |
257 | * from it and kp->opcode. | |
b46b3d70 | 258 | * |
650b7b23 PM |
259 | * In case of Kprobes using ftrace, we do not have a copy of |
260 | * the original instruction. In fact, the ftrace location might | |
261 | * be modified at anytime and even could be in an inconsistent state. | |
262 | * Fortunately, we know that the original code is the ideal 5-byte | |
263 | * long NOP. | |
b46b3d70 | 264 | */ |
650b7b23 PM |
265 | memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
266 | if (faddr) | |
267 | memcpy(buf, ideal_nops[NOP_ATOMIC5], 5); | |
268 | else | |
269 | buf[0] = kp->opcode; | |
86b4ce31 MH |
270 | return (unsigned long)buf; |
271 | } | |
272 | ||
86b4ce31 MH |
273 | /* |
274 | * Recover the probed instruction at addr for further analysis. | |
275 | * Caller must lock kprobes by kprobe_mutex, or disable preemption | |
276 | * for preventing to release referencing kprobes. | |
2a6730c8 | 277 | * Returns zero if the instruction can not get recovered. |
86b4ce31 | 278 | */ |
3f33ab1c | 279 | unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) |
86b4ce31 MH |
280 | { |
281 | unsigned long __addr; | |
282 | ||
283 | __addr = __recover_optprobed_insn(buf, addr); | |
284 | if (__addr != addr) | |
285 | return __addr; | |
286 | ||
287 | return __recover_probed_insn(buf, addr); | |
b46b3d70 MH |
288 | } |
289 | ||
b46b3d70 | 290 | /* Check if paddr is at an instruction boundary */ |
7ec8a97a | 291 | static int can_probe(unsigned long paddr) |
b46b3d70 | 292 | { |
86b4ce31 | 293 | unsigned long addr, __addr, offset = 0; |
b46b3d70 MH |
294 | struct insn insn; |
295 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
296 | ||
6abded71 | 297 | if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) |
b46b3d70 MH |
298 | return 0; |
299 | ||
300 | /* Decode instructions */ | |
301 | addr = paddr - offset; | |
302 | while (addr < paddr) { | |
b46b3d70 MH |
303 | /* |
304 | * Check if the instruction has been modified by another | |
305 | * kprobe, in which case we replace the breakpoint by the | |
306 | * original instruction in our buffer. | |
86b4ce31 MH |
307 | * Also, jump optimization will change the breakpoint to |
308 | * relative-jump. Since the relative-jump itself is | |
309 | * normally used, we just go through if there is no kprobe. | |
b46b3d70 | 310 | */ |
86b4ce31 | 311 | __addr = recover_probed_instruction(buf, addr); |
2a6730c8 PM |
312 | if (!__addr) |
313 | return 0; | |
6ba48ff4 | 314 | kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE); |
b46b3d70 | 315 | insn_get_length(&insn); |
86b4ce31 MH |
316 | |
317 | /* | |
318 | * Another debugging subsystem might insert this breakpoint. | |
319 | * In that case, we can't recover it. | |
320 | */ | |
321 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) | |
322 | return 0; | |
b46b3d70 MH |
323 | addr += insn.length; |
324 | } | |
325 | ||
326 | return (addr == paddr); | |
327 | } | |
328 | ||
1da177e4 | 329 | /* |
d6be29b8 | 330 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 331 | */ |
7ec8a97a | 332 | static int is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 | 333 | { |
567a9fd8 MH |
334 | /* Skip prefixes */ |
335 | insn = skip_prefixes(insn); | |
336 | ||
1da177e4 LT |
337 | switch (*insn) { |
338 | case 0xfa: /* cli */ | |
339 | case 0xfb: /* sti */ | |
340 | case 0xcf: /* iret/iretd */ | |
341 | case 0x9d: /* popf/popfd */ | |
342 | return 1; | |
343 | } | |
9930927f | 344 | |
1da177e4 LT |
345 | return 0; |
346 | } | |
347 | ||
348 | /* | |
c0f7ac3a MH |
349 | * Copy an instruction and adjust the displacement if the instruction |
350 | * uses the %rip-relative addressing mode. | |
aa470140 | 351 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 352 | * If not, return null. |
31f80e45 | 353 | * Only applicable to 64-bit x86. |
1da177e4 | 354 | */ |
7ec8a97a | 355 | int __copy_instruction(u8 *dest, u8 *src) |
1da177e4 | 356 | { |
89ae465b | 357 | struct insn insn; |
c0f7ac3a | 358 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
c80e5c0c | 359 | int length; |
6ba48ff4 DH |
360 | unsigned long recovered_insn = |
361 | recover_probed_instruction(buf, (unsigned long)src); | |
86b4ce31 | 362 | |
2a6730c8 PM |
363 | if (!recovered_insn) |
364 | return 0; | |
6ba48ff4 | 365 | kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); |
c0f7ac3a | 366 | insn_get_length(&insn); |
c80e5c0c ES |
367 | length = insn.length; |
368 | ||
86b4ce31 | 369 | /* Another subsystem puts a breakpoint, failed to recover */ |
46484688 | 370 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) |
86b4ce31 | 371 | return 0; |
c80e5c0c | 372 | memcpy(dest, insn.kaddr, length); |
c0f7ac3a MH |
373 | |
374 | #ifdef CONFIG_X86_64 | |
89ae465b MH |
375 | if (insn_rip_relative(&insn)) { |
376 | s64 newdisp; | |
377 | u8 *disp; | |
c80e5c0c | 378 | kernel_insn_init(&insn, dest, length); |
89ae465b MH |
379 | insn_get_displacement(&insn); |
380 | /* | |
381 | * The copied instruction uses the %rip-relative addressing | |
382 | * mode. Adjust the displacement for the difference between | |
383 | * the original location of this instruction and the location | |
384 | * of the copy that will actually be run. The tricky bit here | |
385 | * is making sure that the sign extension happens correctly in | |
386 | * this calculation, since we need a signed 32-bit result to | |
387 | * be sign-extended to 64 bits when it's added to the %rip | |
388 | * value and yield the same 64-bit result that the sign- | |
389 | * extension of the original signed 32-bit displacement would | |
390 | * have given. | |
391 | */ | |
46484688 | 392 | newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest; |
8101376d MH |
393 | if ((s64) (s32) newdisp != newdisp) { |
394 | pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp); | |
395 | pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value); | |
396 | return 0; | |
397 | } | |
c0f7ac3a | 398 | disp = (u8 *) dest + insn_offset_displacement(&insn); |
89ae465b | 399 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 400 | } |
d6be29b8 | 401 | #endif |
c80e5c0c | 402 | return length; |
31f80e45 | 403 | } |
1da177e4 | 404 | |
7ec8a97a | 405 | static int arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 406 | { |
003002e0 MH |
407 | int ret; |
408 | ||
46484688 | 409 | /* Copy an instruction with recovering if other optprobe modifies it.*/ |
003002e0 MH |
410 | ret = __copy_instruction(p->ainsn.insn, p->addr); |
411 | if (!ret) | |
412 | return -EINVAL; | |
46484688 | 413 | |
c0f7ac3a | 414 | /* |
46484688 MH |
415 | * __copy_instruction can modify the displacement of the instruction, |
416 | * but it doesn't affect boostable check. | |
c0f7ac3a | 417 | */ |
46484688 | 418 | if (can_boost(p->ainsn.insn)) |
aa470140 | 419 | p->ainsn.boostable = 0; |
8533bbe9 | 420 | else |
aa470140 | 421 | p->ainsn.boostable = -1; |
8533bbe9 | 422 | |
9a556ab9 MH |
423 | /* Check whether the instruction modifies Interrupt Flag or not */ |
424 | p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); | |
425 | ||
46484688 MH |
426 | /* Also, displacement change doesn't affect the first byte */ |
427 | p->opcode = p->ainsn.insn[0]; | |
003002e0 MH |
428 | |
429 | return 0; | |
1da177e4 LT |
430 | } |
431 | ||
7ec8a97a | 432 | int arch_prepare_kprobe(struct kprobe *p) |
8533bbe9 | 433 | { |
4554dbcb MH |
434 | if (alternatives_text_reserved(p->addr, p->addr)) |
435 | return -EINVAL; | |
436 | ||
b46b3d70 MH |
437 | if (!can_probe((unsigned long)p->addr)) |
438 | return -EILSEQ; | |
8533bbe9 MH |
439 | /* insn: must be on special executable page on x86. */ |
440 | p->ainsn.insn = get_insn_slot(); | |
441 | if (!p->ainsn.insn) | |
442 | return -ENOMEM; | |
003002e0 MH |
443 | |
444 | return arch_copy_kprobe(p); | |
8533bbe9 MH |
445 | } |
446 | ||
7ec8a97a | 447 | void arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 448 | { |
19d36ccd | 449 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
450 | } |
451 | ||
7ec8a97a | 452 | void arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 453 | { |
19d36ccd | 454 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
455 | } |
456 | ||
7ec8a97a | 457 | void arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 458 | { |
12941560 MH |
459 | if (p->ainsn.insn) { |
460 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
461 | p->ainsn.insn = NULL; | |
462 | } | |
1da177e4 LT |
463 | } |
464 | ||
9326638c MH |
465 | static nokprobe_inline void |
466 | save_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 467 | { |
e7a510f9 AM |
468 | kcb->prev_kprobe.kp = kprobe_running(); |
469 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
470 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
471 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
472 | } |
473 | ||
9326638c MH |
474 | static nokprobe_inline void |
475 | restore_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 476 | { |
b76834bc | 477 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
e7a510f9 | 478 | kcb->kprobe_status = kcb->prev_kprobe.status; |
8533bbe9 MH |
479 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
480 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
481 | } |
482 | ||
9326638c MH |
483 | static nokprobe_inline void |
484 | set_current_kprobe(struct kprobe *p, struct pt_regs *regs, | |
485 | struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 486 | { |
b76834bc | 487 | __this_cpu_write(current_kprobe, p); |
8533bbe9 | 488 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 489 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
9a556ab9 | 490 | if (p->ainsn.if_modifier) |
053de044 | 491 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
492 | } |
493 | ||
9326638c | 494 | static nokprobe_inline void clear_btf(void) |
1ecc798c | 495 | { |
ea8e61b7 PZ |
496 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
497 | unsigned long debugctl = get_debugctlmsr(); | |
498 | ||
499 | debugctl &= ~DEBUGCTLMSR_BTF; | |
500 | update_debugctlmsr(debugctl); | |
501 | } | |
1ecc798c RM |
502 | } |
503 | ||
9326638c | 504 | static nokprobe_inline void restore_btf(void) |
1ecc798c | 505 | { |
ea8e61b7 PZ |
506 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
507 | unsigned long debugctl = get_debugctlmsr(); | |
508 | ||
509 | debugctl |= DEBUGCTLMSR_BTF; | |
510 | update_debugctlmsr(debugctl); | |
511 | } | |
1ecc798c RM |
512 | } |
513 | ||
9326638c | 514 | void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) |
73649dab | 515 | { |
8533bbe9 | 516 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 517 | |
4c4308cb | 518 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 519 | |
4c4308cb CH |
520 | /* Replace the return addr with trampoline addr */ |
521 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 522 | } |
9326638c | 523 | NOKPROBE_SYMBOL(arch_prepare_kretprobe); |
f315decb | 524 | |
9326638c MH |
525 | static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
526 | struct kprobe_ctlblk *kcb, int reenter) | |
f315decb | 527 | { |
c0f7ac3a MH |
528 | if (setup_detour_execution(p, regs, reenter)) |
529 | return; | |
530 | ||
615d0ebb | 531 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
532 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
533 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
534 | if (!reenter) |
535 | reset_current_kprobe(); | |
536 | /* | |
537 | * Reentering boosted probe doesn't reset current_kprobe, | |
538 | * nor set current_kprobe, because it doesn't use single | |
539 | * stepping. | |
540 | */ | |
f315decb AS |
541 | regs->ip = (unsigned long)p->ainsn.insn; |
542 | preempt_enable_no_resched(); | |
543 | return; | |
544 | } | |
545 | #endif | |
0f94eb63 MH |
546 | if (reenter) { |
547 | save_previous_kprobe(kcb); | |
548 | set_current_kprobe(p, regs, kcb); | |
549 | kcb->kprobe_status = KPROBE_REENTER; | |
550 | } else | |
551 | kcb->kprobe_status = KPROBE_HIT_SS; | |
552 | /* Prepare real single stepping */ | |
553 | clear_btf(); | |
554 | regs->flags |= X86_EFLAGS_TF; | |
555 | regs->flags &= ~X86_EFLAGS_IF; | |
556 | /* single step inline if the instruction is an int3 */ | |
557 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
558 | regs->ip = (unsigned long)p->addr; | |
559 | else | |
560 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb | 561 | } |
9326638c | 562 | NOKPROBE_SYMBOL(setup_singlestep); |
f315decb | 563 | |
40102d4a HH |
564 | /* |
565 | * We have reentered the kprobe_handler(), since another probe was hit while | |
566 | * within the handler. We save the original kprobes variables and just single | |
567 | * step on the instruction of the new probe without calling any user handlers. | |
568 | */ | |
9326638c MH |
569 | static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
570 | struct kprobe_ctlblk *kcb) | |
40102d4a | 571 | { |
f315decb AS |
572 | switch (kcb->kprobe_status) { |
573 | case KPROBE_HIT_SSDONE: | |
f315decb | 574 | case KPROBE_HIT_ACTIVE: |
6a5022a5 | 575 | case KPROBE_HIT_SS: |
fb8830e7 | 576 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 577 | setup_singlestep(p, regs, kcb, 1); |
f315decb | 578 | break; |
6a5022a5 | 579 | case KPROBE_REENTER: |
e9afe9e1 MH |
580 | /* A probe has been hit in the codepath leading up to, or just |
581 | * after, single-stepping of a probed instruction. This entire | |
582 | * codepath should strictly reside in .kprobes.text section. | |
583 | * Raise a BUG or we'll continue in an endless reentering loop | |
584 | * and eventually a stack overflow. | |
585 | */ | |
586 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
587 | p->addr); | |
588 | dump_kprobe(p); | |
589 | BUG(); | |
f315decb AS |
590 | default: |
591 | /* impossible cases */ | |
592 | WARN_ON(1); | |
fb8830e7 | 593 | return 0; |
59e87cdc | 594 | } |
f315decb | 595 | |
59e87cdc | 596 | return 1; |
40102d4a | 597 | } |
9326638c | 598 | NOKPROBE_SYMBOL(reenter_kprobe); |
73649dab | 599 | |
8533bbe9 MH |
600 | /* |
601 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 602 | * remain disabled throughout this function. |
8533bbe9 | 603 | */ |
9326638c | 604 | int kprobe_int3_handler(struct pt_regs *regs) |
1da177e4 | 605 | { |
8533bbe9 | 606 | kprobe_opcode_t *addr; |
f315decb | 607 | struct kprobe *p; |
d217d545 AM |
608 | struct kprobe_ctlblk *kcb; |
609 | ||
f39b6f0e | 610 | if (user_mode(regs)) |
0cdd192c AL |
611 | return 0; |
612 | ||
8533bbe9 | 613 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
614 | /* |
615 | * We don't want to be preempted for the entire | |
f315decb AS |
616 | * duration of kprobe processing. We conditionally |
617 | * re-enable preemption at the end of this function, | |
618 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
619 | */ |
620 | preempt_disable(); | |
1da177e4 | 621 | |
f315decb | 622 | kcb = get_kprobe_ctlblk(); |
b9760156 | 623 | p = get_kprobe(addr); |
f315decb | 624 | |
b9760156 | 625 | if (p) { |
b9760156 | 626 | if (kprobe_running()) { |
f315decb AS |
627 | if (reenter_kprobe(p, regs, kcb)) |
628 | return 1; | |
1da177e4 | 629 | } else { |
b9760156 HH |
630 | set_current_kprobe(p, regs, kcb); |
631 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 632 | |
1da177e4 | 633 | /* |
f315decb AS |
634 | * If we have no pre-handler or it returned 0, we |
635 | * continue with normal processing. If we have a | |
636 | * pre-handler and it returned non-zero, it prepped | |
637 | * for calling the break_handler below on re-entry | |
638 | * for jprobe processing, so get out doing nothing | |
639 | * more here. | |
1da177e4 | 640 | */ |
f315decb | 641 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 642 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 643 | return 1; |
b9760156 | 644 | } |
829e9245 MH |
645 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
646 | /* | |
647 | * The breakpoint instruction was removed right | |
648 | * after we hit it. Another cpu has removed | |
649 | * either a probepoint or a debugger breakpoint | |
650 | * at this address. In either case, no further | |
651 | * handling of this interrupt is appropriate. | |
652 | * Back up over the (now missing) int3 and run | |
653 | * the original instruction. | |
654 | */ | |
655 | regs->ip = (unsigned long)addr; | |
656 | preempt_enable_no_resched(); | |
657 | return 1; | |
f315decb | 658 | } else if (kprobe_running()) { |
b76834bc | 659 | p = __this_cpu_read(current_kprobe); |
f315decb | 660 | if (p->break_handler && p->break_handler(p, regs)) { |
e7dbfe34 MH |
661 | if (!skip_singlestep(p, regs, kcb)) |
662 | setup_singlestep(p, regs, kcb, 0); | |
f315decb | 663 | return 1; |
1da177e4 | 664 | } |
f315decb | 665 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 666 | |
d217d545 | 667 | preempt_enable_no_resched(); |
f315decb | 668 | return 0; |
1da177e4 | 669 | } |
9326638c | 670 | NOKPROBE_SYMBOL(kprobe_int3_handler); |
1da177e4 | 671 | |
73649dab | 672 | /* |
da07ab03 MH |
673 | * When a retprobed function returns, this code saves registers and |
674 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 675 | */ |
c1c355ce JP |
676 | asm( |
677 | ".global kretprobe_trampoline\n" | |
678 | ".type kretprobe_trampoline, @function\n" | |
679 | "kretprobe_trampoline:\n" | |
d6be29b8 | 680 | #ifdef CONFIG_X86_64 |
c1c355ce JP |
681 | /* We don't bother saving the ss register */ |
682 | " pushq %rsp\n" | |
683 | " pushfq\n" | |
684 | SAVE_REGS_STRING | |
685 | " movq %rsp, %rdi\n" | |
686 | " call trampoline_handler\n" | |
687 | /* Replace saved sp with true return address. */ | |
688 | " movq %rax, 152(%rsp)\n" | |
689 | RESTORE_REGS_STRING | |
690 | " popfq\n" | |
d6be29b8 | 691 | #else |
c1c355ce JP |
692 | " pushf\n" |
693 | SAVE_REGS_STRING | |
694 | " movl %esp, %eax\n" | |
695 | " call trampoline_handler\n" | |
696 | /* Move flags to cs */ | |
697 | " movl 56(%esp), %edx\n" | |
698 | " movl %edx, 52(%esp)\n" | |
699 | /* Replace saved flags with true return address. */ | |
700 | " movl %eax, 56(%esp)\n" | |
701 | RESTORE_REGS_STRING | |
702 | " popf\n" | |
d6be29b8 | 703 | #endif |
c1c355ce JP |
704 | " ret\n" |
705 | ".size kretprobe_trampoline, .-kretprobe_trampoline\n" | |
706 | ); | |
9326638c | 707 | NOKPROBE_SYMBOL(kretprobe_trampoline); |
87aaff2a | 708 | STACK_FRAME_NON_STANDARD(kretprobe_trampoline); |
73649dab RL |
709 | |
710 | /* | |
da07ab03 | 711 | * Called from kretprobe_trampoline |
73649dab | 712 | */ |
9326638c | 713 | __visible __used void *trampoline_handler(struct pt_regs *regs) |
73649dab | 714 | { |
62c27be0 | 715 | struct kretprobe_instance *ri = NULL; |
99219a3f | 716 | struct hlist_head *head, empty_rp; |
b67bfe0d | 717 | struct hlist_node *tmp; |
991a51d8 | 718 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 719 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
737480a0 | 720 | kprobe_opcode_t *correct_ret_addr = NULL; |
73649dab | 721 | |
99219a3f | 722 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 723 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 724 | /* fixup registers */ |
d6be29b8 | 725 | #ifdef CONFIG_X86_64 |
da07ab03 | 726 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
727 | #else |
728 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 729 | regs->gs = 0; |
d6be29b8 | 730 | #endif |
da07ab03 | 731 | regs->ip = trampoline_address; |
8533bbe9 | 732 | regs->orig_ax = ~0UL; |
73649dab | 733 | |
ba8af12f RL |
734 | /* |
735 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 736 | * task either because multiple functions in the call path have |
025dfdaf | 737 | * return probes installed on them, and/or more than one |
ba8af12f RL |
738 | * return probe was registered for a target function. |
739 | * | |
740 | * We can handle this because: | |
8533bbe9 | 741 | * - instances are always pushed into the head of the list |
ba8af12f | 742 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
743 | * function, the (chronologically) first instance's ret_addr |
744 | * will be the real return address, and all the rest will | |
745 | * point to kretprobe_trampoline. | |
ba8af12f | 746 | */ |
b67bfe0d | 747 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
62c27be0 | 748 | if (ri->task != current) |
ba8af12f | 749 | /* another task is sharing our hash bucket */ |
62c27be0 | 750 | continue; |
ba8af12f | 751 | |
737480a0 KS |
752 | orig_ret_address = (unsigned long)ri->ret_addr; |
753 | ||
754 | if (orig_ret_address != trampoline_address) | |
755 | /* | |
756 | * This is the real return address. Any other | |
757 | * instances associated with this task are for | |
758 | * other calls deeper on the call stack | |
759 | */ | |
760 | break; | |
761 | } | |
762 | ||
763 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
764 | ||
765 | correct_ret_addr = ri->ret_addr; | |
b67bfe0d | 766 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
737480a0 KS |
767 | if (ri->task != current) |
768 | /* another task is sharing our hash bucket */ | |
769 | continue; | |
770 | ||
771 | orig_ret_address = (unsigned long)ri->ret_addr; | |
da07ab03 | 772 | if (ri->rp && ri->rp->handler) { |
b76834bc | 773 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
da07ab03 | 774 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
737480a0 | 775 | ri->ret_addr = correct_ret_addr; |
ba8af12f | 776 | ri->rp->handler(ri, regs); |
b76834bc | 777 | __this_cpu_write(current_kprobe, NULL); |
da07ab03 | 778 | } |
ba8af12f | 779 | |
99219a3f | 780 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
781 | |
782 | if (orig_ret_address != trampoline_address) | |
783 | /* | |
784 | * This is the real return address. Any other | |
785 | * instances associated with this task are for | |
786 | * other calls deeper on the call stack | |
787 | */ | |
788 | break; | |
73649dab | 789 | } |
ba8af12f | 790 | |
ef53d9c5 | 791 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 792 | |
b67bfe0d | 793 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 794 | hlist_del(&ri->hlist); |
795 | kfree(ri); | |
796 | } | |
da07ab03 | 797 | return (void *)orig_ret_address; |
73649dab | 798 | } |
9326638c | 799 | NOKPROBE_SYMBOL(trampoline_handler); |
73649dab | 800 | |
1da177e4 LT |
801 | /* |
802 | * Called after single-stepping. p->addr is the address of the | |
803 | * instruction whose first byte has been replaced by the "int 3" | |
804 | * instruction. To avoid the SMP problems that can occur when we | |
805 | * temporarily put back the original opcode to single-step, we | |
806 | * single-stepped a copy of the instruction. The address of this | |
807 | * copy is p->ainsn.insn. | |
808 | * | |
809 | * This function prepares to return from the post-single-step | |
810 | * interrupt. We have to fix up the stack as follows: | |
811 | * | |
812 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 813 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
814 | * it relative to the original instruction. |
815 | * | |
816 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 817 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
818 | * |
819 | * 2) If the single-stepped instruction was a call, the return address | |
820 | * that is atop the stack is the address following the copied instruction. | |
821 | * We need to make it the address following the original instruction. | |
aa470140 MH |
822 | * |
823 | * If this is the first time we've single-stepped the instruction at | |
824 | * this probepoint, and the instruction is boostable, boost it: add a | |
825 | * jump instruction after the copied instruction, that jumps to the next | |
826 | * instruction after the probepoint. | |
1da177e4 | 827 | */ |
9326638c MH |
828 | static void resume_execution(struct kprobe *p, struct pt_regs *regs, |
829 | struct kprobe_ctlblk *kcb) | |
1da177e4 | 830 | { |
8533bbe9 MH |
831 | unsigned long *tos = stack_addr(regs); |
832 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
833 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
834 | kprobe_opcode_t *insn = p->ainsn.insn; |
835 | ||
567a9fd8 MH |
836 | /* Skip prefixes */ |
837 | insn = skip_prefixes(insn); | |
1da177e4 | 838 | |
053de044 | 839 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 840 | switch (*insn) { |
0b0122fa | 841 | case 0x9c: /* pushfl */ |
053de044 | 842 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 843 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 844 | break; |
0b0122fa MH |
845 | case 0xc2: /* iret/ret/lret */ |
846 | case 0xc3: | |
0b9e2cac | 847 | case 0xca: |
0b0122fa MH |
848 | case 0xcb: |
849 | case 0xcf: | |
850 | case 0xea: /* jmp absolute -- ip is correct */ | |
851 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 852 | p->ainsn.boostable = 1; |
0b0122fa MH |
853 | goto no_change; |
854 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 855 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 856 | break; |
e7b5e11e | 857 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
858 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
859 | *tos = orig_ip + (*tos - copy_ip); | |
860 | goto no_change; | |
861 | #endif | |
1da177e4 | 862 | case 0xff: |
dc49e344 | 863 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
864 | /* |
865 | * call absolute, indirect | |
866 | * Fix return addr; ip is correct. | |
867 | * But this is not boostable | |
868 | */ | |
869 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 870 | goto no_change; |
8533bbe9 MH |
871 | } else if (((insn[1] & 0x31) == 0x20) || |
872 | ((insn[1] & 0x31) == 0x21)) { | |
873 | /* | |
874 | * jmp near and far, absolute indirect | |
875 | * ip is correct. And this is boostable | |
876 | */ | |
aa470140 | 877 | p->ainsn.boostable = 1; |
0b0122fa | 878 | goto no_change; |
1da177e4 | 879 | } |
1da177e4 LT |
880 | default: |
881 | break; | |
882 | } | |
883 | ||
aa470140 | 884 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
885 | if ((regs->ip > copy_ip) && |
886 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
887 | /* |
888 | * These instructions can be executed directly if it | |
889 | * jumps back to correct address. | |
890 | */ | |
c0f7ac3a MH |
891 | synthesize_reljump((void *)regs->ip, |
892 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
893 | p->ainsn.boostable = 1; |
894 | } else { | |
895 | p->ainsn.boostable = -1; | |
896 | } | |
897 | } | |
898 | ||
8533bbe9 | 899 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 900 | |
0b0122fa | 901 | no_change: |
1ecc798c | 902 | restore_btf(); |
1da177e4 | 903 | } |
9326638c | 904 | NOKPROBE_SYMBOL(resume_execution); |
1da177e4 | 905 | |
8533bbe9 MH |
906 | /* |
907 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 908 | * remain disabled throughout this function. |
8533bbe9 | 909 | */ |
9326638c | 910 | int kprobe_debug_handler(struct pt_regs *regs) |
1da177e4 | 911 | { |
e7a510f9 AM |
912 | struct kprobe *cur = kprobe_running(); |
913 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
914 | ||
915 | if (!cur) | |
1da177e4 LT |
916 | return 0; |
917 | ||
acb5b8a2 YL |
918 | resume_execution(cur, regs, kcb); |
919 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 920 | |
e7a510f9 AM |
921 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
922 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
923 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 924 | } |
1da177e4 | 925 | |
8533bbe9 | 926 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
927 | if (kcb->kprobe_status == KPROBE_REENTER) { |
928 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 929 | goto out; |
aa3d7e3d | 930 | } |
e7a510f9 | 931 | reset_current_kprobe(); |
aa3d7e3d | 932 | out: |
1da177e4 LT |
933 | preempt_enable_no_resched(); |
934 | ||
935 | /* | |
65ea5b03 | 936 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
937 | * will have TF set, in which case, continue the remaining processing |
938 | * of do_debug, as if this is not a probe hit. | |
939 | */ | |
053de044 | 940 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
941 | return 0; |
942 | ||
943 | return 1; | |
944 | } | |
9326638c | 945 | NOKPROBE_SYMBOL(kprobe_debug_handler); |
1da177e4 | 946 | |
9326638c | 947 | int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 948 | { |
e7a510f9 AM |
949 | struct kprobe *cur = kprobe_running(); |
950 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
951 | ||
6381c24c MH |
952 | if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) { |
953 | /* This must happen on single-stepping */ | |
954 | WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS && | |
955 | kcb->kprobe_status != KPROBE_REENTER); | |
c28f8966 PP |
956 | /* |
957 | * We are here because the instruction being single | |
958 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 959 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
960 | * and allow the page fault handler to continue as a |
961 | * normal page fault. | |
962 | */ | |
65ea5b03 | 963 | regs->ip = (unsigned long)cur->addr; |
dcfc4724 MH |
964 | /* |
965 | * Trap flag (TF) has been set here because this fault | |
966 | * happened where the single stepping will be done. | |
967 | * So clear it by resetting the current kprobe: | |
968 | */ | |
969 | regs->flags &= ~X86_EFLAGS_TF; | |
970 | ||
971 | /* | |
972 | * If the TF flag was set before the kprobe hit, | |
973 | * don't touch it: | |
974 | */ | |
8533bbe9 | 975 | regs->flags |= kcb->kprobe_old_flags; |
dcfc4724 | 976 | |
c28f8966 PP |
977 | if (kcb->kprobe_status == KPROBE_REENTER) |
978 | restore_previous_kprobe(kcb); | |
979 | else | |
980 | reset_current_kprobe(); | |
1da177e4 | 981 | preempt_enable_no_resched(); |
6381c24c MH |
982 | } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE || |
983 | kcb->kprobe_status == KPROBE_HIT_SSDONE) { | |
c28f8966 PP |
984 | /* |
985 | * We increment the nmissed count for accounting, | |
8533bbe9 | 986 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
987 | * these specific fault cases. |
988 | */ | |
989 | kprobes_inc_nmissed_count(cur); | |
990 | ||
991 | /* | |
992 | * We come here because instructions in the pre/post | |
993 | * handler caused the page_fault, this could happen | |
994 | * if handler tries to access user space by | |
995 | * copy_from_user(), get_user() etc. Let the | |
996 | * user-specified handler try to fix it first. | |
997 | */ | |
998 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
999 | return 1; | |
1000 | ||
1001 | /* | |
1002 | * In case the user-specified fault handler returned | |
1003 | * zero, try to fix up. | |
1004 | */ | |
548acf19 | 1005 | if (fixup_exception(regs, trapnr)) |
d6be29b8 | 1006 | return 1; |
6d48583b | 1007 | |
c28f8966 | 1008 | /* |
8533bbe9 | 1009 | * fixup routine could not handle it, |
c28f8966 PP |
1010 | * Let do_page_fault() fix it. |
1011 | */ | |
1da177e4 | 1012 | } |
6381c24c | 1013 | |
1da177e4 LT |
1014 | return 0; |
1015 | } | |
9326638c | 1016 | NOKPROBE_SYMBOL(kprobe_fault_handler); |
1da177e4 LT |
1017 | |
1018 | /* | |
1019 | * Wrapper routine for handling exceptions. | |
1020 | */ | |
9326638c MH |
1021 | int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, |
1022 | void *data) | |
1da177e4 | 1023 | { |
ade1af77 | 1024 | struct die_args *args = data; |
66ff2d06 AM |
1025 | int ret = NOTIFY_DONE; |
1026 | ||
f39b6f0e | 1027 | if (args->regs && user_mode(args->regs)) |
2326c770 | 1028 | return ret; |
1029 | ||
6f6343f5 | 1030 | if (val == DIE_GPF) { |
b506a9d0 QB |
1031 | /* |
1032 | * To be potentially processing a kprobe fault and to | |
1033 | * trust the result from kprobe_running(), we have | |
1034 | * be non-preemptible. | |
1035 | */ | |
1036 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1037 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1038 | ret = NOTIFY_STOP; |
1da177e4 | 1039 | } |
66ff2d06 | 1040 | return ret; |
1da177e4 | 1041 | } |
9326638c | 1042 | NOKPROBE_SYMBOL(kprobe_exceptions_notify); |
1da177e4 | 1043 | |
9326638c | 1044 | int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1045 | { |
1046 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1047 | unsigned long addr; | |
e7a510f9 | 1048 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1049 | |
e7a510f9 | 1050 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1051 | kcb->jprobe_saved_sp = stack_addr(regs); |
1052 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1053 | ||
1da177e4 LT |
1054 | /* |
1055 | * As Linus pointed out, gcc assumes that the callee | |
1056 | * owns the argument space and could overwrite it, e.g. | |
1057 | * tailcall optimization. So, to be absolutely safe | |
1058 | * we also save and restore enough stack bytes to cover | |
1059 | * the argument area. | |
1060 | */ | |
e7a510f9 | 1061 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1062 | MIN_STACK_SIZE(addr)); |
053de044 | 1063 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1064 | trace_hardirqs_off(); |
65ea5b03 | 1065 | regs->ip = (unsigned long)(jp->entry); |
237d28db SRRH |
1066 | |
1067 | /* | |
1068 | * jprobes use jprobe_return() which skips the normal return | |
1069 | * path of the function, and this messes up the accounting of the | |
1070 | * function graph tracer to get messed up. | |
1071 | * | |
1072 | * Pause function graph tracing while performing the jprobe function. | |
1073 | */ | |
1074 | pause_graph_tracing(); | |
1da177e4 LT |
1075 | return 1; |
1076 | } | |
9326638c | 1077 | NOKPROBE_SYMBOL(setjmp_pre_handler); |
1da177e4 | 1078 | |
9326638c | 1079 | void jprobe_return(void) |
1da177e4 | 1080 | { |
e7a510f9 AM |
1081 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1082 | ||
d6be29b8 MH |
1083 | asm volatile ( |
1084 | #ifdef CONFIG_X86_64 | |
1085 | " xchg %%rbx,%%rsp \n" | |
1086 | #else | |
1087 | " xchgl %%ebx,%%esp \n" | |
1088 | #endif | |
1089 | " int3 \n" | |
1090 | " .globl jprobe_return_end\n" | |
1091 | " jprobe_return_end: \n" | |
1092 | " nop \n"::"b" | |
1093 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 | 1094 | } |
9326638c MH |
1095 | NOKPROBE_SYMBOL(jprobe_return); |
1096 | NOKPROBE_SYMBOL(jprobe_return_end); | |
1da177e4 | 1097 | |
9326638c | 1098 | int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1099 | { |
e7a510f9 | 1100 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1101 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 | 1102 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
237d28db | 1103 | void *saved_sp = kcb->jprobe_saved_sp; |
1da177e4 | 1104 | |
d6be29b8 MH |
1105 | if ((addr > (u8 *) jprobe_return) && |
1106 | (addr < (u8 *) jprobe_return_end)) { | |
237d28db | 1107 | if (stack_addr(regs) != saved_sp) { |
29b6cd79 | 1108 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1109 | printk(KERN_ERR |
1110 | "current sp %p does not match saved sp %p\n", | |
237d28db | 1111 | stack_addr(regs), saved_sp); |
d6be29b8 | 1112 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
57da8b96 | 1113 | show_regs(saved_regs); |
d6be29b8 | 1114 | printk(KERN_ERR "Current registers\n"); |
57da8b96 | 1115 | show_regs(regs); |
1da177e4 LT |
1116 | BUG(); |
1117 | } | |
237d28db SRRH |
1118 | /* It's OK to start function graph tracing again */ |
1119 | unpause_graph_tracing(); | |
e7a510f9 | 1120 | *regs = kcb->jprobe_saved_regs; |
237d28db | 1121 | memcpy(saved_sp, kcb->jprobes_stack, MIN_STACK_SIZE(saved_sp)); |
d217d545 | 1122 | preempt_enable_no_resched(); |
1da177e4 LT |
1123 | return 1; |
1124 | } | |
1125 | return 0; | |
1126 | } | |
9326638c | 1127 | NOKPROBE_SYMBOL(longjmp_break_handler); |
ba8af12f | 1128 | |
be8f2743 MH |
1129 | bool arch_within_kprobe_blacklist(unsigned long addr) |
1130 | { | |
1131 | return (addr >= (unsigned long)__kprobes_text_start && | |
1132 | addr < (unsigned long)__kprobes_text_end) || | |
1133 | (addr >= (unsigned long)__entry_text_start && | |
1134 | addr < (unsigned long)__entry_text_end); | |
1135 | } | |
1136 | ||
6772926b | 1137 | int __init arch_init_kprobes(void) |
ba8af12f | 1138 | { |
a7b0133e | 1139 | return 0; |
ba8af12f | 1140 | } |
bf8f6e5b | 1141 | |
7ec8a97a | 1142 | int arch_trampoline_kprobe(struct kprobe *p) |
bf8f6e5b | 1143 | { |
bf8f6e5b AM |
1144 | return 0; |
1145 | } |