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> |
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 */ | |
b7e37567 | 87 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */ |
8533bbe9 MH |
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 | ||
9326638c MH |
115 | static nokprobe_inline void |
116 | __synthesize_relative_insn(void *from, void *to, u8 op) | |
aa470140 | 117 | { |
c0f7ac3a MH |
118 | struct __arch_relative_insn { |
119 | u8 op; | |
aa470140 | 120 | s32 raddr; |
f684199f | 121 | } __packed *insn; |
c0f7ac3a MH |
122 | |
123 | insn = (struct __arch_relative_insn *)from; | |
124 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
125 | insn->op = op; | |
126 | } | |
127 | ||
128 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
9326638c | 129 | void synthesize_reljump(void *from, void *to) |
c0f7ac3a MH |
130 | { |
131 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 | 132 | } |
9326638c | 133 | NOKPROBE_SYMBOL(synthesize_reljump); |
aa470140 | 134 | |
3f33ab1c | 135 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ |
9326638c | 136 | void synthesize_relcall(void *from, void *to) |
3f33ab1c MH |
137 | { |
138 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
139 | } | |
9326638c | 140 | NOKPROBE_SYMBOL(synthesize_relcall); |
3f33ab1c | 141 | |
9930927f | 142 | /* |
567a9fd8 | 143 | * Skip the prefixes of the instruction. |
9930927f | 144 | */ |
9326638c | 145 | static kprobe_opcode_t *skip_prefixes(kprobe_opcode_t *insn) |
9930927f | 146 | { |
567a9fd8 MH |
147 | insn_attr_t attr; |
148 | ||
149 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
150 | while (inat_is_legacy_prefix(attr)) { | |
151 | insn++; | |
152 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
153 | } | |
9930927f | 154 | #ifdef CONFIG_X86_64 |
567a9fd8 MH |
155 | if (inat_is_rex_prefix(attr)) |
156 | insn++; | |
9930927f | 157 | #endif |
567a9fd8 | 158 | return insn; |
9930927f | 159 | } |
9326638c | 160 | NOKPROBE_SYMBOL(skip_prefixes); |
9930927f | 161 | |
aa470140 | 162 | /* |
d6be29b8 MH |
163 | * Returns non-zero if opcode is boostable. |
164 | * RIP relative instructions are adjusted at copying time in 64 bits mode | |
aa470140 | 165 | */ |
7ec8a97a | 166 | int can_boost(kprobe_opcode_t *opcodes) |
aa470140 | 167 | { |
aa470140 MH |
168 | kprobe_opcode_t opcode; |
169 | kprobe_opcode_t *orig_opcodes = opcodes; | |
170 | ||
cde5edbd | 171 | if (search_exception_tables((unsigned long)opcodes)) |
30390880 MH |
172 | return 0; /* Page fault may occur on this address. */ |
173 | ||
aa470140 MH |
174 | retry: |
175 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
176 | return 0; | |
177 | opcode = *(opcodes++); | |
178 | ||
179 | /* 2nd-byte opcode */ | |
180 | if (opcode == 0x0f) { | |
181 | if (opcodes - orig_opcodes > MAX_INSN_SIZE - 1) | |
182 | return 0; | |
8533bbe9 MH |
183 | return test_bit(*opcodes, |
184 | (unsigned long *)twobyte_is_boostable); | |
aa470140 MH |
185 | } |
186 | ||
187 | switch (opcode & 0xf0) { | |
d6be29b8 | 188 | #ifdef CONFIG_X86_64 |
aa470140 MH |
189 | case 0x40: |
190 | goto retry; /* REX prefix is boostable */ | |
d6be29b8 | 191 | #endif |
aa470140 MH |
192 | case 0x60: |
193 | if (0x63 < opcode && opcode < 0x67) | |
194 | goto retry; /* prefixes */ | |
195 | /* can't boost Address-size override and bound */ | |
196 | return (opcode != 0x62 && opcode != 0x67); | |
197 | case 0x70: | |
198 | return 0; /* can't boost conditional jump */ | |
199 | case 0xc0: | |
200 | /* can't boost software-interruptions */ | |
201 | return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf; | |
202 | case 0xd0: | |
203 | /* can boost AA* and XLAT */ | |
204 | return (opcode == 0xd4 || opcode == 0xd5 || opcode == 0xd7); | |
205 | case 0xe0: | |
206 | /* can boost in/out and absolute jmps */ | |
207 | return ((opcode & 0x04) || opcode == 0xea); | |
208 | case 0xf0: | |
209 | if ((opcode & 0x0c) == 0 && opcode != 0xf1) | |
210 | goto retry; /* lock/rep(ne) prefix */ | |
211 | /* clear and set flags are boostable */ | |
212 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
213 | default: | |
214 | /* segment override prefixes are boostable */ | |
215 | if (opcode == 0x26 || opcode == 0x36 || opcode == 0x3e) | |
216 | goto retry; /* prefixes */ | |
217 | /* CS override prefix and call are not boostable */ | |
218 | return (opcode != 0x2e && opcode != 0x9a); | |
219 | } | |
220 | } | |
221 | ||
3f33ab1c MH |
222 | static unsigned long |
223 | __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) | |
b46b3d70 MH |
224 | { |
225 | struct kprobe *kp; | |
650b7b23 | 226 | unsigned long faddr; |
86b4ce31 | 227 | |
b46b3d70 | 228 | kp = get_kprobe((void *)addr); |
650b7b23 | 229 | faddr = ftrace_location(addr); |
2a6730c8 PM |
230 | /* |
231 | * Addresses inside the ftrace location are refused by | |
232 | * arch_check_ftrace_location(). Something went terribly wrong | |
233 | * if such an address is checked here. | |
234 | */ | |
235 | if (WARN_ON(faddr && faddr != addr)) | |
236 | return 0UL; | |
650b7b23 PM |
237 | /* |
238 | * Use the current code if it is not modified by Kprobe | |
239 | * and it cannot be modified by ftrace. | |
240 | */ | |
241 | if (!kp && !faddr) | |
86b4ce31 | 242 | return addr; |
b46b3d70 MH |
243 | |
244 | /* | |
650b7b23 PM |
245 | * Basically, kp->ainsn.insn has an original instruction. |
246 | * However, RIP-relative instruction can not do single-stepping | |
247 | * at different place, __copy_instruction() tweaks the displacement of | |
248 | * that instruction. In that case, we can't recover the instruction | |
249 | * from the kp->ainsn.insn. | |
250 | * | |
251 | * On the other hand, in case on normal Kprobe, kp->opcode has a copy | |
252 | * of the first byte of the probed instruction, which is overwritten | |
253 | * by int3. And the instruction at kp->addr is not modified by kprobes | |
254 | * except for the first byte, we can recover the original instruction | |
255 | * from it and kp->opcode. | |
b46b3d70 | 256 | * |
650b7b23 PM |
257 | * In case of Kprobes using ftrace, we do not have a copy of |
258 | * the original instruction. In fact, the ftrace location might | |
259 | * be modified at anytime and even could be in an inconsistent state. | |
260 | * Fortunately, we know that the original code is the ideal 5-byte | |
261 | * long NOP. | |
b46b3d70 | 262 | */ |
650b7b23 PM |
263 | memcpy(buf, (void *)addr, MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); |
264 | if (faddr) | |
265 | memcpy(buf, ideal_nops[NOP_ATOMIC5], 5); | |
266 | else | |
267 | buf[0] = kp->opcode; | |
86b4ce31 MH |
268 | return (unsigned long)buf; |
269 | } | |
270 | ||
86b4ce31 MH |
271 | /* |
272 | * Recover the probed instruction at addr for further analysis. | |
273 | * Caller must lock kprobes by kprobe_mutex, or disable preemption | |
274 | * for preventing to release referencing kprobes. | |
2a6730c8 | 275 | * Returns zero if the instruction can not get recovered. |
86b4ce31 | 276 | */ |
3f33ab1c | 277 | unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) |
86b4ce31 MH |
278 | { |
279 | unsigned long __addr; | |
280 | ||
281 | __addr = __recover_optprobed_insn(buf, addr); | |
282 | if (__addr != addr) | |
283 | return __addr; | |
284 | ||
285 | return __recover_probed_insn(buf, addr); | |
b46b3d70 MH |
286 | } |
287 | ||
b46b3d70 | 288 | /* Check if paddr is at an instruction boundary */ |
7ec8a97a | 289 | static int can_probe(unsigned long paddr) |
b46b3d70 | 290 | { |
86b4ce31 | 291 | unsigned long addr, __addr, offset = 0; |
b46b3d70 MH |
292 | struct insn insn; |
293 | kprobe_opcode_t buf[MAX_INSN_SIZE]; | |
294 | ||
6abded71 | 295 | if (!kallsyms_lookup_size_offset(paddr, NULL, &offset)) |
b46b3d70 MH |
296 | return 0; |
297 | ||
298 | /* Decode instructions */ | |
299 | addr = paddr - offset; | |
300 | while (addr < paddr) { | |
b46b3d70 MH |
301 | /* |
302 | * Check if the instruction has been modified by another | |
303 | * kprobe, in which case we replace the breakpoint by the | |
304 | * original instruction in our buffer. | |
86b4ce31 MH |
305 | * Also, jump optimization will change the breakpoint to |
306 | * relative-jump. Since the relative-jump itself is | |
307 | * normally used, we just go through if there is no kprobe. | |
b46b3d70 | 308 | */ |
86b4ce31 | 309 | __addr = recover_probed_instruction(buf, addr); |
2a6730c8 PM |
310 | if (!__addr) |
311 | return 0; | |
6ba48ff4 | 312 | kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE); |
b46b3d70 | 313 | insn_get_length(&insn); |
86b4ce31 MH |
314 | |
315 | /* | |
316 | * Another debugging subsystem might insert this breakpoint. | |
317 | * In that case, we can't recover it. | |
318 | */ | |
319 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) | |
320 | return 0; | |
b46b3d70 MH |
321 | addr += insn.length; |
322 | } | |
323 | ||
324 | return (addr == paddr); | |
325 | } | |
326 | ||
1da177e4 | 327 | /* |
d6be29b8 | 328 | * Returns non-zero if opcode modifies the interrupt flag. |
1da177e4 | 329 | */ |
7ec8a97a | 330 | static int is_IF_modifier(kprobe_opcode_t *insn) |
1da177e4 | 331 | { |
567a9fd8 MH |
332 | /* Skip prefixes */ |
333 | insn = skip_prefixes(insn); | |
334 | ||
1da177e4 LT |
335 | switch (*insn) { |
336 | case 0xfa: /* cli */ | |
337 | case 0xfb: /* sti */ | |
338 | case 0xcf: /* iret/iretd */ | |
339 | case 0x9d: /* popf/popfd */ | |
340 | return 1; | |
341 | } | |
9930927f | 342 | |
1da177e4 LT |
343 | return 0; |
344 | } | |
345 | ||
346 | /* | |
c0f7ac3a MH |
347 | * Copy an instruction and adjust the displacement if the instruction |
348 | * uses the %rip-relative addressing mode. | |
aa470140 | 349 | * If it does, Return the address of the 32-bit displacement word. |
1da177e4 | 350 | * If not, return null. |
31f80e45 | 351 | * Only applicable to 64-bit x86. |
1da177e4 | 352 | */ |
7ec8a97a | 353 | int __copy_instruction(u8 *dest, u8 *src) |
1da177e4 | 354 | { |
89ae465b | 355 | struct insn insn; |
c0f7ac3a | 356 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
6ba48ff4 DH |
357 | unsigned long recovered_insn = |
358 | recover_probed_instruction(buf, (unsigned long)src); | |
86b4ce31 | 359 | |
2a6730c8 PM |
360 | if (!recovered_insn) |
361 | return 0; | |
6ba48ff4 | 362 | kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE); |
c0f7ac3a | 363 | insn_get_length(&insn); |
86b4ce31 | 364 | /* Another subsystem puts a breakpoint, failed to recover */ |
46484688 | 365 | if (insn.opcode.bytes[0] == BREAKPOINT_INSTRUCTION) |
86b4ce31 | 366 | return 0; |
c0f7ac3a MH |
367 | memcpy(dest, insn.kaddr, insn.length); |
368 | ||
369 | #ifdef CONFIG_X86_64 | |
89ae465b MH |
370 | if (insn_rip_relative(&insn)) { |
371 | s64 newdisp; | |
372 | u8 *disp; | |
6ba48ff4 | 373 | kernel_insn_init(&insn, dest, insn.length); |
89ae465b MH |
374 | insn_get_displacement(&insn); |
375 | /* | |
376 | * The copied instruction uses the %rip-relative addressing | |
377 | * mode. Adjust the displacement for the difference between | |
378 | * the original location of this instruction and the location | |
379 | * of the copy that will actually be run. The tricky bit here | |
380 | * is making sure that the sign extension happens correctly in | |
381 | * this calculation, since we need a signed 32-bit result to | |
382 | * be sign-extended to 64 bits when it's added to the %rip | |
383 | * value and yield the same 64-bit result that the sign- | |
384 | * extension of the original signed 32-bit displacement would | |
385 | * have given. | |
386 | */ | |
46484688 | 387 | newdisp = (u8 *) src + (s64) insn.displacement.value - (u8 *) dest; |
8101376d MH |
388 | if ((s64) (s32) newdisp != newdisp) { |
389 | pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp); | |
390 | pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", src, dest, insn.displacement.value); | |
391 | return 0; | |
392 | } | |
c0f7ac3a | 393 | disp = (u8 *) dest + insn_offset_displacement(&insn); |
89ae465b | 394 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 395 | } |
d6be29b8 | 396 | #endif |
c0f7ac3a | 397 | return insn.length; |
31f80e45 | 398 | } |
1da177e4 | 399 | |
7ec8a97a | 400 | static int arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 401 | { |
003002e0 MH |
402 | int ret; |
403 | ||
46484688 | 404 | /* Copy an instruction with recovering if other optprobe modifies it.*/ |
003002e0 MH |
405 | ret = __copy_instruction(p->ainsn.insn, p->addr); |
406 | if (!ret) | |
407 | return -EINVAL; | |
46484688 | 408 | |
c0f7ac3a | 409 | /* |
46484688 MH |
410 | * __copy_instruction can modify the displacement of the instruction, |
411 | * but it doesn't affect boostable check. | |
c0f7ac3a | 412 | */ |
46484688 | 413 | if (can_boost(p->ainsn.insn)) |
aa470140 | 414 | p->ainsn.boostable = 0; |
8533bbe9 | 415 | else |
aa470140 | 416 | p->ainsn.boostable = -1; |
8533bbe9 | 417 | |
9a556ab9 MH |
418 | /* Check whether the instruction modifies Interrupt Flag or not */ |
419 | p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); | |
420 | ||
46484688 MH |
421 | /* Also, displacement change doesn't affect the first byte */ |
422 | p->opcode = p->ainsn.insn[0]; | |
003002e0 MH |
423 | |
424 | return 0; | |
1da177e4 LT |
425 | } |
426 | ||
7ec8a97a | 427 | int arch_prepare_kprobe(struct kprobe *p) |
8533bbe9 | 428 | { |
4554dbcb MH |
429 | if (alternatives_text_reserved(p->addr, p->addr)) |
430 | return -EINVAL; | |
431 | ||
b46b3d70 MH |
432 | if (!can_probe((unsigned long)p->addr)) |
433 | return -EILSEQ; | |
8533bbe9 MH |
434 | /* insn: must be on special executable page on x86. */ |
435 | p->ainsn.insn = get_insn_slot(); | |
436 | if (!p->ainsn.insn) | |
437 | return -ENOMEM; | |
003002e0 MH |
438 | |
439 | return arch_copy_kprobe(p); | |
8533bbe9 MH |
440 | } |
441 | ||
7ec8a97a | 442 | void arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 443 | { |
19d36ccd | 444 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
445 | } |
446 | ||
7ec8a97a | 447 | void arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 448 | { |
19d36ccd | 449 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
450 | } |
451 | ||
7ec8a97a | 452 | void arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 453 | { |
12941560 MH |
454 | if (p->ainsn.insn) { |
455 | free_insn_slot(p->ainsn.insn, (p->ainsn.boostable == 1)); | |
456 | p->ainsn.insn = NULL; | |
457 | } | |
1da177e4 LT |
458 | } |
459 | ||
9326638c MH |
460 | static nokprobe_inline void |
461 | save_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 462 | { |
e7a510f9 AM |
463 | kcb->prev_kprobe.kp = kprobe_running(); |
464 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
465 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
466 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
467 | } |
468 | ||
9326638c MH |
469 | static nokprobe_inline void |
470 | restore_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 471 | { |
b76834bc | 472 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
e7a510f9 | 473 | kcb->kprobe_status = kcb->prev_kprobe.status; |
8533bbe9 MH |
474 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
475 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
476 | } |
477 | ||
9326638c MH |
478 | static nokprobe_inline void |
479 | set_current_kprobe(struct kprobe *p, struct pt_regs *regs, | |
480 | struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 481 | { |
b76834bc | 482 | __this_cpu_write(current_kprobe, p); |
8533bbe9 | 483 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 484 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
9a556ab9 | 485 | if (p->ainsn.if_modifier) |
053de044 | 486 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
487 | } |
488 | ||
9326638c | 489 | static nokprobe_inline void clear_btf(void) |
1ecc798c | 490 | { |
ea8e61b7 PZ |
491 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
492 | unsigned long debugctl = get_debugctlmsr(); | |
493 | ||
494 | debugctl &= ~DEBUGCTLMSR_BTF; | |
495 | update_debugctlmsr(debugctl); | |
496 | } | |
1ecc798c RM |
497 | } |
498 | ||
9326638c | 499 | static nokprobe_inline void restore_btf(void) |
1ecc798c | 500 | { |
ea8e61b7 PZ |
501 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
502 | unsigned long debugctl = get_debugctlmsr(); | |
503 | ||
504 | debugctl |= DEBUGCTLMSR_BTF; | |
505 | update_debugctlmsr(debugctl); | |
506 | } | |
1ecc798c RM |
507 | } |
508 | ||
9326638c | 509 | void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) |
73649dab | 510 | { |
8533bbe9 | 511 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 512 | |
4c4308cb | 513 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 514 | |
4c4308cb CH |
515 | /* Replace the return addr with trampoline addr */ |
516 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 517 | } |
9326638c | 518 | NOKPROBE_SYMBOL(arch_prepare_kretprobe); |
f315decb | 519 | |
9326638c MH |
520 | static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
521 | struct kprobe_ctlblk *kcb, int reenter) | |
f315decb | 522 | { |
c0f7ac3a MH |
523 | if (setup_detour_execution(p, regs, reenter)) |
524 | return; | |
525 | ||
615d0ebb | 526 | #if !defined(CONFIG_PREEMPT) |
f315decb AS |
527 | if (p->ainsn.boostable == 1 && !p->post_handler) { |
528 | /* Boost up -- we can execute copied instructions directly */ | |
0f94eb63 MH |
529 | if (!reenter) |
530 | reset_current_kprobe(); | |
531 | /* | |
532 | * Reentering boosted probe doesn't reset current_kprobe, | |
533 | * nor set current_kprobe, because it doesn't use single | |
534 | * stepping. | |
535 | */ | |
f315decb AS |
536 | regs->ip = (unsigned long)p->ainsn.insn; |
537 | preempt_enable_no_resched(); | |
538 | return; | |
539 | } | |
540 | #endif | |
0f94eb63 MH |
541 | if (reenter) { |
542 | save_previous_kprobe(kcb); | |
543 | set_current_kprobe(p, regs, kcb); | |
544 | kcb->kprobe_status = KPROBE_REENTER; | |
545 | } else | |
546 | kcb->kprobe_status = KPROBE_HIT_SS; | |
547 | /* Prepare real single stepping */ | |
548 | clear_btf(); | |
549 | regs->flags |= X86_EFLAGS_TF; | |
550 | regs->flags &= ~X86_EFLAGS_IF; | |
551 | /* single step inline if the instruction is an int3 */ | |
552 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
553 | regs->ip = (unsigned long)p->addr; | |
554 | else | |
555 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb | 556 | } |
9326638c | 557 | NOKPROBE_SYMBOL(setup_singlestep); |
f315decb | 558 | |
40102d4a HH |
559 | /* |
560 | * We have reentered the kprobe_handler(), since another probe was hit while | |
561 | * within the handler. We save the original kprobes variables and just single | |
562 | * step on the instruction of the new probe without calling any user handlers. | |
563 | */ | |
9326638c MH |
564 | static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
565 | struct kprobe_ctlblk *kcb) | |
40102d4a | 566 | { |
f315decb AS |
567 | switch (kcb->kprobe_status) { |
568 | case KPROBE_HIT_SSDONE: | |
f315decb | 569 | case KPROBE_HIT_ACTIVE: |
6a5022a5 | 570 | case KPROBE_HIT_SS: |
fb8830e7 | 571 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 572 | setup_singlestep(p, regs, kcb, 1); |
f315decb | 573 | break; |
6a5022a5 | 574 | case KPROBE_REENTER: |
e9afe9e1 MH |
575 | /* A probe has been hit in the codepath leading up to, or just |
576 | * after, single-stepping of a probed instruction. This entire | |
577 | * codepath should strictly reside in .kprobes.text section. | |
578 | * Raise a BUG or we'll continue in an endless reentering loop | |
579 | * and eventually a stack overflow. | |
580 | */ | |
581 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
582 | p->addr); | |
583 | dump_kprobe(p); | |
584 | BUG(); | |
f315decb AS |
585 | default: |
586 | /* impossible cases */ | |
587 | WARN_ON(1); | |
fb8830e7 | 588 | return 0; |
59e87cdc | 589 | } |
f315decb | 590 | |
59e87cdc | 591 | return 1; |
40102d4a | 592 | } |
9326638c | 593 | NOKPROBE_SYMBOL(reenter_kprobe); |
73649dab | 594 | |
8533bbe9 MH |
595 | /* |
596 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 597 | * remain disabled throughout this function. |
8533bbe9 | 598 | */ |
9326638c | 599 | int kprobe_int3_handler(struct pt_regs *regs) |
1da177e4 | 600 | { |
8533bbe9 | 601 | kprobe_opcode_t *addr; |
f315decb | 602 | struct kprobe *p; |
d217d545 AM |
603 | struct kprobe_ctlblk *kcb; |
604 | ||
0cdd192c AL |
605 | if (user_mode_vm(regs)) |
606 | return 0; | |
607 | ||
8533bbe9 | 608 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
609 | /* |
610 | * We don't want to be preempted for the entire | |
f315decb AS |
611 | * duration of kprobe processing. We conditionally |
612 | * re-enable preemption at the end of this function, | |
613 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
614 | */ |
615 | preempt_disable(); | |
1da177e4 | 616 | |
f315decb | 617 | kcb = get_kprobe_ctlblk(); |
b9760156 | 618 | p = get_kprobe(addr); |
f315decb | 619 | |
b9760156 | 620 | if (p) { |
b9760156 | 621 | if (kprobe_running()) { |
f315decb AS |
622 | if (reenter_kprobe(p, regs, kcb)) |
623 | return 1; | |
1da177e4 | 624 | } else { |
b9760156 HH |
625 | set_current_kprobe(p, regs, kcb); |
626 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 627 | |
1da177e4 | 628 | /* |
f315decb AS |
629 | * If we have no pre-handler or it returned 0, we |
630 | * continue with normal processing. If we have a | |
631 | * pre-handler and it returned non-zero, it prepped | |
632 | * for calling the break_handler below on re-entry | |
633 | * for jprobe processing, so get out doing nothing | |
634 | * more here. | |
1da177e4 | 635 | */ |
f315decb | 636 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 637 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 638 | return 1; |
b9760156 | 639 | } |
829e9245 MH |
640 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
641 | /* | |
642 | * The breakpoint instruction was removed right | |
643 | * after we hit it. Another cpu has removed | |
644 | * either a probepoint or a debugger breakpoint | |
645 | * at this address. In either case, no further | |
646 | * handling of this interrupt is appropriate. | |
647 | * Back up over the (now missing) int3 and run | |
648 | * the original instruction. | |
649 | */ | |
650 | regs->ip = (unsigned long)addr; | |
651 | preempt_enable_no_resched(); | |
652 | return 1; | |
f315decb | 653 | } else if (kprobe_running()) { |
b76834bc | 654 | p = __this_cpu_read(current_kprobe); |
f315decb | 655 | if (p->break_handler && p->break_handler(p, regs)) { |
e7dbfe34 MH |
656 | if (!skip_singlestep(p, regs, kcb)) |
657 | setup_singlestep(p, regs, kcb, 0); | |
f315decb | 658 | return 1; |
1da177e4 | 659 | } |
f315decb | 660 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 661 | |
d217d545 | 662 | preempt_enable_no_resched(); |
f315decb | 663 | return 0; |
1da177e4 | 664 | } |
9326638c | 665 | NOKPROBE_SYMBOL(kprobe_int3_handler); |
1da177e4 | 666 | |
73649dab | 667 | /* |
da07ab03 MH |
668 | * When a retprobed function returns, this code saves registers and |
669 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 670 | */ |
9326638c | 671 | static void __used kretprobe_trampoline_holder(void) |
1017579a | 672 | { |
d6be29b8 MH |
673 | asm volatile ( |
674 | ".global kretprobe_trampoline\n" | |
da07ab03 | 675 | "kretprobe_trampoline: \n" |
d6be29b8 | 676 | #ifdef CONFIG_X86_64 |
da07ab03 MH |
677 | /* We don't bother saving the ss register */ |
678 | " pushq %rsp\n" | |
679 | " pushfq\n" | |
f007ea26 | 680 | SAVE_REGS_STRING |
da07ab03 MH |
681 | " movq %rsp, %rdi\n" |
682 | " call trampoline_handler\n" | |
683 | /* Replace saved sp with true return address. */ | |
684 | " movq %rax, 152(%rsp)\n" | |
f007ea26 | 685 | RESTORE_REGS_STRING |
da07ab03 | 686 | " popfq\n" |
d6be29b8 MH |
687 | #else |
688 | " pushf\n" | |
f007ea26 | 689 | SAVE_REGS_STRING |
d6be29b8 MH |
690 | " movl %esp, %eax\n" |
691 | " call trampoline_handler\n" | |
692 | /* Move flags to cs */ | |
fee039a1 MH |
693 | " movl 56(%esp), %edx\n" |
694 | " movl %edx, 52(%esp)\n" | |
d6be29b8 | 695 | /* Replace saved flags with true return address. */ |
fee039a1 | 696 | " movl %eax, 56(%esp)\n" |
f007ea26 | 697 | RESTORE_REGS_STRING |
d6be29b8 MH |
698 | " popf\n" |
699 | #endif | |
da07ab03 | 700 | " ret\n"); |
1017579a | 701 | } |
9326638c MH |
702 | NOKPROBE_SYMBOL(kretprobe_trampoline_holder); |
703 | NOKPROBE_SYMBOL(kretprobe_trampoline); | |
73649dab RL |
704 | |
705 | /* | |
da07ab03 | 706 | * Called from kretprobe_trampoline |
73649dab | 707 | */ |
9326638c | 708 | __visible __used void *trampoline_handler(struct pt_regs *regs) |
73649dab | 709 | { |
62c27be0 | 710 | struct kretprobe_instance *ri = NULL; |
99219a3f | 711 | struct hlist_head *head, empty_rp; |
b67bfe0d | 712 | struct hlist_node *tmp; |
991a51d8 | 713 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 714 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
737480a0 | 715 | kprobe_opcode_t *correct_ret_addr = NULL; |
73649dab | 716 | |
99219a3f | 717 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 718 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 719 | /* fixup registers */ |
d6be29b8 | 720 | #ifdef CONFIG_X86_64 |
da07ab03 | 721 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
722 | #else |
723 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 724 | regs->gs = 0; |
d6be29b8 | 725 | #endif |
da07ab03 | 726 | regs->ip = trampoline_address; |
8533bbe9 | 727 | regs->orig_ax = ~0UL; |
73649dab | 728 | |
ba8af12f RL |
729 | /* |
730 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 731 | * task either because multiple functions in the call path have |
025dfdaf | 732 | * return probes installed on them, and/or more than one |
ba8af12f RL |
733 | * return probe was registered for a target function. |
734 | * | |
735 | * We can handle this because: | |
8533bbe9 | 736 | * - instances are always pushed into the head of the list |
ba8af12f | 737 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
738 | * function, the (chronologically) first instance's ret_addr |
739 | * will be the real return address, and all the rest will | |
740 | * point to kretprobe_trampoline. | |
ba8af12f | 741 | */ |
b67bfe0d | 742 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
62c27be0 | 743 | if (ri->task != current) |
ba8af12f | 744 | /* another task is sharing our hash bucket */ |
62c27be0 | 745 | continue; |
ba8af12f | 746 | |
737480a0 KS |
747 | orig_ret_address = (unsigned long)ri->ret_addr; |
748 | ||
749 | if (orig_ret_address != trampoline_address) | |
750 | /* | |
751 | * This is the real return address. Any other | |
752 | * instances associated with this task are for | |
753 | * other calls deeper on the call stack | |
754 | */ | |
755 | break; | |
756 | } | |
757 | ||
758 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
759 | ||
760 | correct_ret_addr = ri->ret_addr; | |
b67bfe0d | 761 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
737480a0 KS |
762 | if (ri->task != current) |
763 | /* another task is sharing our hash bucket */ | |
764 | continue; | |
765 | ||
766 | orig_ret_address = (unsigned long)ri->ret_addr; | |
da07ab03 | 767 | if (ri->rp && ri->rp->handler) { |
b76834bc | 768 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
da07ab03 | 769 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
737480a0 | 770 | ri->ret_addr = correct_ret_addr; |
ba8af12f | 771 | ri->rp->handler(ri, regs); |
b76834bc | 772 | __this_cpu_write(current_kprobe, NULL); |
da07ab03 | 773 | } |
ba8af12f | 774 | |
99219a3f | 775 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
776 | |
777 | if (orig_ret_address != trampoline_address) | |
778 | /* | |
779 | * This is the real return address. Any other | |
780 | * instances associated with this task are for | |
781 | * other calls deeper on the call stack | |
782 | */ | |
783 | break; | |
73649dab | 784 | } |
ba8af12f | 785 | |
ef53d9c5 | 786 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 787 | |
b67bfe0d | 788 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 789 | hlist_del(&ri->hlist); |
790 | kfree(ri); | |
791 | } | |
da07ab03 | 792 | return (void *)orig_ret_address; |
73649dab | 793 | } |
9326638c | 794 | NOKPROBE_SYMBOL(trampoline_handler); |
73649dab | 795 | |
1da177e4 LT |
796 | /* |
797 | * Called after single-stepping. p->addr is the address of the | |
798 | * instruction whose first byte has been replaced by the "int 3" | |
799 | * instruction. To avoid the SMP problems that can occur when we | |
800 | * temporarily put back the original opcode to single-step, we | |
801 | * single-stepped a copy of the instruction. The address of this | |
802 | * copy is p->ainsn.insn. | |
803 | * | |
804 | * This function prepares to return from the post-single-step | |
805 | * interrupt. We have to fix up the stack as follows: | |
806 | * | |
807 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 808 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
809 | * it relative to the original instruction. |
810 | * | |
811 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 812 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
813 | * |
814 | * 2) If the single-stepped instruction was a call, the return address | |
815 | * that is atop the stack is the address following the copied instruction. | |
816 | * We need to make it the address following the original instruction. | |
aa470140 MH |
817 | * |
818 | * If this is the first time we've single-stepped the instruction at | |
819 | * this probepoint, and the instruction is boostable, boost it: add a | |
820 | * jump instruction after the copied instruction, that jumps to the next | |
821 | * instruction after the probepoint. | |
1da177e4 | 822 | */ |
9326638c MH |
823 | static void resume_execution(struct kprobe *p, struct pt_regs *regs, |
824 | struct kprobe_ctlblk *kcb) | |
1da177e4 | 825 | { |
8533bbe9 MH |
826 | unsigned long *tos = stack_addr(regs); |
827 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
828 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
829 | kprobe_opcode_t *insn = p->ainsn.insn; |
830 | ||
567a9fd8 MH |
831 | /* Skip prefixes */ |
832 | insn = skip_prefixes(insn); | |
1da177e4 | 833 | |
053de044 | 834 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 835 | switch (*insn) { |
0b0122fa | 836 | case 0x9c: /* pushfl */ |
053de044 | 837 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 838 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 839 | break; |
0b0122fa MH |
840 | case 0xc2: /* iret/ret/lret */ |
841 | case 0xc3: | |
0b9e2cac | 842 | case 0xca: |
0b0122fa MH |
843 | case 0xcb: |
844 | case 0xcf: | |
845 | case 0xea: /* jmp absolute -- ip is correct */ | |
846 | /* ip is already adjusted, no more changes required */ | |
aa470140 | 847 | p->ainsn.boostable = 1; |
0b0122fa MH |
848 | goto no_change; |
849 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 850 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 851 | break; |
e7b5e11e | 852 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
853 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
854 | *tos = orig_ip + (*tos - copy_ip); | |
855 | goto no_change; | |
856 | #endif | |
1da177e4 | 857 | case 0xff: |
dc49e344 | 858 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
859 | /* |
860 | * call absolute, indirect | |
861 | * Fix return addr; ip is correct. | |
862 | * But this is not boostable | |
863 | */ | |
864 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 865 | goto no_change; |
8533bbe9 MH |
866 | } else if (((insn[1] & 0x31) == 0x20) || |
867 | ((insn[1] & 0x31) == 0x21)) { | |
868 | /* | |
869 | * jmp near and far, absolute indirect | |
870 | * ip is correct. And this is boostable | |
871 | */ | |
aa470140 | 872 | p->ainsn.boostable = 1; |
0b0122fa | 873 | goto no_change; |
1da177e4 | 874 | } |
1da177e4 LT |
875 | default: |
876 | break; | |
877 | } | |
878 | ||
aa470140 | 879 | if (p->ainsn.boostable == 0) { |
8533bbe9 MH |
880 | if ((regs->ip > copy_ip) && |
881 | (regs->ip - copy_ip) + 5 < MAX_INSN_SIZE) { | |
aa470140 MH |
882 | /* |
883 | * These instructions can be executed directly if it | |
884 | * jumps back to correct address. | |
885 | */ | |
c0f7ac3a MH |
886 | synthesize_reljump((void *)regs->ip, |
887 | (void *)orig_ip + (regs->ip - copy_ip)); | |
aa470140 MH |
888 | p->ainsn.boostable = 1; |
889 | } else { | |
890 | p->ainsn.boostable = -1; | |
891 | } | |
892 | } | |
893 | ||
8533bbe9 | 894 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 895 | |
0b0122fa | 896 | no_change: |
1ecc798c | 897 | restore_btf(); |
1da177e4 | 898 | } |
9326638c | 899 | NOKPROBE_SYMBOL(resume_execution); |
1da177e4 | 900 | |
8533bbe9 MH |
901 | /* |
902 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 903 | * remain disabled throughout this function. |
8533bbe9 | 904 | */ |
9326638c | 905 | int kprobe_debug_handler(struct pt_regs *regs) |
1da177e4 | 906 | { |
e7a510f9 AM |
907 | struct kprobe *cur = kprobe_running(); |
908 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
909 | ||
910 | if (!cur) | |
1da177e4 LT |
911 | return 0; |
912 | ||
acb5b8a2 YL |
913 | resume_execution(cur, regs, kcb); |
914 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 915 | |
e7a510f9 AM |
916 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
917 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
918 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 919 | } |
1da177e4 | 920 | |
8533bbe9 | 921 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
922 | if (kcb->kprobe_status == KPROBE_REENTER) { |
923 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 924 | goto out; |
aa3d7e3d | 925 | } |
e7a510f9 | 926 | reset_current_kprobe(); |
aa3d7e3d | 927 | out: |
1da177e4 LT |
928 | preempt_enable_no_resched(); |
929 | ||
930 | /* | |
65ea5b03 | 931 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
932 | * will have TF set, in which case, continue the remaining processing |
933 | * of do_debug, as if this is not a probe hit. | |
934 | */ | |
053de044 | 935 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
936 | return 0; |
937 | ||
938 | return 1; | |
939 | } | |
9326638c | 940 | NOKPROBE_SYMBOL(kprobe_debug_handler); |
1da177e4 | 941 | |
9326638c | 942 | int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 943 | { |
e7a510f9 AM |
944 | struct kprobe *cur = kprobe_running(); |
945 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
946 | ||
6381c24c MH |
947 | if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) { |
948 | /* This must happen on single-stepping */ | |
949 | WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS && | |
950 | kcb->kprobe_status != KPROBE_REENTER); | |
c28f8966 PP |
951 | /* |
952 | * We are here because the instruction being single | |
953 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 954 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
955 | * and allow the page fault handler to continue as a |
956 | * normal page fault. | |
957 | */ | |
65ea5b03 | 958 | regs->ip = (unsigned long)cur->addr; |
8533bbe9 | 959 | regs->flags |= kcb->kprobe_old_flags; |
c28f8966 PP |
960 | if (kcb->kprobe_status == KPROBE_REENTER) |
961 | restore_previous_kprobe(kcb); | |
962 | else | |
963 | reset_current_kprobe(); | |
1da177e4 | 964 | preempt_enable_no_resched(); |
6381c24c MH |
965 | } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE || |
966 | kcb->kprobe_status == KPROBE_HIT_SSDONE) { | |
c28f8966 PP |
967 | /* |
968 | * We increment the nmissed count for accounting, | |
8533bbe9 | 969 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
970 | * these specific fault cases. |
971 | */ | |
972 | kprobes_inc_nmissed_count(cur); | |
973 | ||
974 | /* | |
975 | * We come here because instructions in the pre/post | |
976 | * handler caused the page_fault, this could happen | |
977 | * if handler tries to access user space by | |
978 | * copy_from_user(), get_user() etc. Let the | |
979 | * user-specified handler try to fix it first. | |
980 | */ | |
981 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
982 | return 1; | |
983 | ||
984 | /* | |
985 | * In case the user-specified fault handler returned | |
986 | * zero, try to fix up. | |
987 | */ | |
d6be29b8 MH |
988 | if (fixup_exception(regs)) |
989 | return 1; | |
6d48583b | 990 | |
c28f8966 | 991 | /* |
8533bbe9 | 992 | * fixup routine could not handle it, |
c28f8966 PP |
993 | * Let do_page_fault() fix it. |
994 | */ | |
1da177e4 | 995 | } |
6381c24c | 996 | |
1da177e4 LT |
997 | return 0; |
998 | } | |
9326638c | 999 | NOKPROBE_SYMBOL(kprobe_fault_handler); |
1da177e4 LT |
1000 | |
1001 | /* | |
1002 | * Wrapper routine for handling exceptions. | |
1003 | */ | |
9326638c MH |
1004 | int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, |
1005 | void *data) | |
1da177e4 | 1006 | { |
ade1af77 | 1007 | struct die_args *args = data; |
66ff2d06 AM |
1008 | int ret = NOTIFY_DONE; |
1009 | ||
8533bbe9 | 1010 | if (args->regs && user_mode_vm(args->regs)) |
2326c770 | 1011 | return ret; |
1012 | ||
6f6343f5 | 1013 | if (val == DIE_GPF) { |
b506a9d0 QB |
1014 | /* |
1015 | * To be potentially processing a kprobe fault and to | |
1016 | * trust the result from kprobe_running(), we have | |
1017 | * be non-preemptible. | |
1018 | */ | |
1019 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1020 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1021 | ret = NOTIFY_STOP; |
1da177e4 | 1022 | } |
66ff2d06 | 1023 | return ret; |
1da177e4 | 1024 | } |
9326638c | 1025 | NOKPROBE_SYMBOL(kprobe_exceptions_notify); |
1da177e4 | 1026 | |
9326638c | 1027 | int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1028 | { |
1029 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1030 | unsigned long addr; | |
e7a510f9 | 1031 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1032 | |
e7a510f9 | 1033 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1034 | kcb->jprobe_saved_sp = stack_addr(regs); |
1035 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1036 | ||
1da177e4 LT |
1037 | /* |
1038 | * As Linus pointed out, gcc assumes that the callee | |
1039 | * owns the argument space and could overwrite it, e.g. | |
1040 | * tailcall optimization. So, to be absolutely safe | |
1041 | * we also save and restore enough stack bytes to cover | |
1042 | * the argument area. | |
1043 | */ | |
e7a510f9 | 1044 | memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, |
d6be29b8 | 1045 | MIN_STACK_SIZE(addr)); |
053de044 | 1046 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1047 | trace_hardirqs_off(); |
65ea5b03 | 1048 | regs->ip = (unsigned long)(jp->entry); |
237d28db SRRH |
1049 | |
1050 | /* | |
1051 | * jprobes use jprobe_return() which skips the normal return | |
1052 | * path of the function, and this messes up the accounting of the | |
1053 | * function graph tracer to get messed up. | |
1054 | * | |
1055 | * Pause function graph tracing while performing the jprobe function. | |
1056 | */ | |
1057 | pause_graph_tracing(); | |
1da177e4 LT |
1058 | return 1; |
1059 | } | |
9326638c | 1060 | NOKPROBE_SYMBOL(setjmp_pre_handler); |
1da177e4 | 1061 | |
9326638c | 1062 | void jprobe_return(void) |
1da177e4 | 1063 | { |
e7a510f9 AM |
1064 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1065 | ||
d6be29b8 MH |
1066 | asm volatile ( |
1067 | #ifdef CONFIG_X86_64 | |
1068 | " xchg %%rbx,%%rsp \n" | |
1069 | #else | |
1070 | " xchgl %%ebx,%%esp \n" | |
1071 | #endif | |
1072 | " int3 \n" | |
1073 | " .globl jprobe_return_end\n" | |
1074 | " jprobe_return_end: \n" | |
1075 | " nop \n"::"b" | |
1076 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 | 1077 | } |
9326638c MH |
1078 | NOKPROBE_SYMBOL(jprobe_return); |
1079 | NOKPROBE_SYMBOL(jprobe_return_end); | |
1da177e4 | 1080 | |
9326638c | 1081 | int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1082 | { |
e7a510f9 | 1083 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1084 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 | 1085 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
237d28db | 1086 | void *saved_sp = kcb->jprobe_saved_sp; |
1da177e4 | 1087 | |
d6be29b8 MH |
1088 | if ((addr > (u8 *) jprobe_return) && |
1089 | (addr < (u8 *) jprobe_return_end)) { | |
237d28db | 1090 | if (stack_addr(regs) != saved_sp) { |
29b6cd79 | 1091 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1092 | printk(KERN_ERR |
1093 | "current sp %p does not match saved sp %p\n", | |
237d28db | 1094 | stack_addr(regs), saved_sp); |
d6be29b8 | 1095 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
57da8b96 | 1096 | show_regs(saved_regs); |
d6be29b8 | 1097 | printk(KERN_ERR "Current registers\n"); |
57da8b96 | 1098 | show_regs(regs); |
1da177e4 LT |
1099 | BUG(); |
1100 | } | |
237d28db SRRH |
1101 | /* It's OK to start function graph tracing again */ |
1102 | unpause_graph_tracing(); | |
e7a510f9 | 1103 | *regs = kcb->jprobe_saved_regs; |
237d28db | 1104 | memcpy(saved_sp, kcb->jprobes_stack, MIN_STACK_SIZE(saved_sp)); |
d217d545 | 1105 | preempt_enable_no_resched(); |
1da177e4 LT |
1106 | return 1; |
1107 | } | |
1108 | return 0; | |
1109 | } | |
9326638c | 1110 | NOKPROBE_SYMBOL(longjmp_break_handler); |
ba8af12f | 1111 | |
be8f2743 MH |
1112 | bool arch_within_kprobe_blacklist(unsigned long addr) |
1113 | { | |
1114 | return (addr >= (unsigned long)__kprobes_text_start && | |
1115 | addr < (unsigned long)__kprobes_text_end) || | |
1116 | (addr >= (unsigned long)__entry_text_start && | |
1117 | addr < (unsigned long)__entry_text_end); | |
1118 | } | |
1119 | ||
6772926b | 1120 | int __init arch_init_kprobes(void) |
ba8af12f | 1121 | { |
a7b0133e | 1122 | return 0; |
ba8af12f | 1123 | } |
bf8f6e5b | 1124 | |
7ec8a97a | 1125 | int arch_trampoline_kprobe(struct kprobe *p) |
bf8f6e5b | 1126 | { |
bf8f6e5b AM |
1127 | return 0; |
1128 | } |