1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * Kernel Probes (KProbes) |
4 | * |
5 | * Copyright (C) IBM Corporation, 2002, 2004 |
6 | * |
7 | * 2002-Oct Created by Vamsi Krishna S <vamsi_krishna@in.ibm.com> Kernel |
8 | * Probes initial implementation ( includes contributions from |
9 | * Rusty Russell). |
10 | * 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes |
11 | * interface to access function arguments. |
12 | * 2004-Oct Jim Keniston <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
13 | * <prasanna@in.ibm.com> adapted for x86_64 from i386. |
14 | * 2005-Mar Roland McGrath <roland@redhat.com> |
15 | * Fixed to handle %rip-relative addressing mode correctly. |
16 | * 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston |
17 | * <jkenisto@us.ibm.com> and Prasanna S Panchamukhi |
18 | * <prasanna@in.ibm.com> added function-return probes. |
19 | * 2005-May Rusty Lynch <rusty.lynch@intel.com> |
20 | * Added function return probes functionality |
21 | * 2006-Feb Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp> added |
22 | * kprobe-booster and kretprobe-booster for i386. |
23 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com> added kprobe-booster |
24 | * and kretprobe-booster for x86-64 |
25 | * 2007-Dec Masami Hiramatsu <mhiramat@redhat.com>, Arjan van de Ven |
26 | * <arjan@infradead.org> and Jim Keniston <jkenisto@us.ibm.com> |
27 | * unified x86 kprobes code. |
28 | */ |
29 | #include <linux/kprobes.h> |
30 | #include <linux/ptrace.h> |
31 | #include <linux/string.h> |
32 | #include <linux/slab.h> |
33 | #include <linux/hardirq.h> |
34 | #include <linux/preempt.h> |
35 | #include <linux/sched/debug.h> |
36 | #include <linux/perf_event.h> |
37 | #include <linux/extable.h> |
38 | #include <linux/kdebug.h> |
39 | #include <linux/kallsyms.h> |
40 | #include <linux/kgdb.h> |
41 | #include <linux/ftrace.h> |
42 | #include <linux/kasan.h> |
43 | #include <linux/moduleloader.h> |
44 | #include <linux/objtool.h> |
45 | #include <linux/vmalloc.h> |
46 | #include <linux/pgtable.h> |
47 | #include <linux/set_memory.h> |
48 | #include <linux/cfi.h> |
49 | |
50 | #include <asm/text-patching.h> |
51 | #include <asm/cacheflush.h> |
52 | #include <asm/desc.h> |
53 | #include <linux/uaccess.h> |
54 | #include <asm/alternative.h> |
55 | #include <asm/insn.h> |
56 | #include <asm/debugreg.h> |
57 | #include <asm/ibt.h> |
58 | |
59 | #include "common.h" |
60 | |
61 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
62 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); |
63 | |
64 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ |
65 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ |
66 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ |
67 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ |
68 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ |
69 | << (row % 32)) |
70 | /* |
71 | * Undefined/reserved opcodes, conditional jump, Opcode Extension |
72 | * Groups, and some special opcodes can not boost. |
73 | * This is non-const and volatile to keep gcc from statically |
74 | * optimizing it out, as variable_test_bit makes gcc think only |
75 | * *(unsigned long*) is used. |
76 | */ |
77 | static volatile u32 twobyte_is_boostable[256 / 32] = { |
78 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
79 | /* ---------------------------------------------- */ |
80 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ |
81 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */ |
82 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ |
83 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ |
84 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ |
85 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ |
86 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ |
87 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ |
88 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ |
89 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ |
90 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ |
91 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ |
92 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ |
93 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ |
94 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ |
95 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ |
96 | /* ----------------------------------------------- */ |
97 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
98 | }; |
99 | #undef W |
100 | |
101 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
102 | {"__switch_to" , }, /* This function switches only current task, but |
103 | doesn't switch kernel stack.*/ |
104 | {NULL, NULL} /* Terminator */ |
105 | }; |
106 | |
107 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); |
108 | |
109 | static nokprobe_inline void |
110 | __synthesize_relative_insn(void *dest, void *from, void *to, u8 op) |
111 | { |
112 | struct __arch_relative_insn { |
113 | u8 op; |
114 | s32 raddr; |
115 | } __packed *insn; |
116 | |
117 | insn = (struct __arch_relative_insn *)dest; |
118 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); |
119 | insn->op = op; |
120 | } |
121 | |
122 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ |
123 | void synthesize_reljump(void *dest, void *from, void *to) |
124 | { |
125 | __synthesize_relative_insn(dest, from, to, JMP32_INSN_OPCODE); |
126 | } |
127 | NOKPROBE_SYMBOL(synthesize_reljump); |
128 | |
129 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ |
130 | void synthesize_relcall(void *dest, void *from, void *to) |
131 | { |
132 | __synthesize_relative_insn(dest, from, to, CALL_INSN_OPCODE); |
133 | } |
134 | NOKPROBE_SYMBOL(synthesize_relcall); |
135 | |
136 | /* |
137 | * Returns non-zero if INSN is boostable. |
138 | * RIP relative instructions are adjusted at copying time in 64 bits mode |
139 | */ |
140 | bool can_boost(struct insn *insn, void *addr) |
141 | { |
142 | kprobe_opcode_t opcode; |
143 | insn_byte_t prefix; |
144 | int i; |
145 | |
146 | if (search_exception_tables(add: (unsigned long)addr)) |
147 | return false; /* Page fault may occur on this address. */ |
148 | |
149 | /* 2nd-byte opcode */ |
150 | if (insn->opcode.nbytes == 2) |
151 | return test_bit(insn->opcode.bytes[1], |
152 | (unsigned long *)twobyte_is_boostable); |
153 | |
154 | if (insn->opcode.nbytes != 1) |
155 | return false; |
156 | |
157 | for_each_insn_prefix(insn, i, prefix) { |
158 | insn_attr_t attr; |
159 | |
160 | attr = inat_get_opcode_attribute(opcode: prefix); |
161 | /* Can't boost Address-size override prefix and CS override prefix */ |
162 | if (prefix == 0x2e || inat_is_address_size_prefix(attr)) |
163 | return false; |
164 | } |
165 | |
166 | opcode = insn->opcode.bytes[0]; |
167 | |
168 | switch (opcode) { |
169 | case 0x62: /* bound */ |
170 | case 0x70 ... 0x7f: /* Conditional jumps */ |
171 | case 0x9a: /* Call far */ |
172 | case 0xcc ... 0xce: /* software exceptions */ |
173 | case 0xd6: /* (UD) */ |
174 | case 0xd8 ... 0xdf: /* ESC */ |
175 | case 0xe0 ... 0xe3: /* LOOP*, JCXZ */ |
176 | case 0xe8 ... 0xe9: /* near Call, JMP */ |
177 | case 0xeb: /* Short JMP */ |
178 | case 0xf0 ... 0xf4: /* LOCK/REP, HLT */ |
179 | /* ... are not boostable */ |
180 | return false; |
181 | case 0xc0 ... 0xc1: /* Grp2 */ |
182 | case 0xd0 ... 0xd3: /* Grp2 */ |
183 | /* |
184 | * AMD uses nnn == 110 as SHL/SAL, but Intel makes it reserved. |
185 | */ |
186 | return X86_MODRM_REG(insn->modrm.bytes[0]) != 0b110; |
187 | case 0xf6 ... 0xf7: /* Grp3 */ |
188 | /* AMD uses nnn == 001 as TEST, but Intel makes it reserved. */ |
189 | return X86_MODRM_REG(insn->modrm.bytes[0]) != 0b001; |
190 | case 0xfe: /* Grp4 */ |
191 | /* Only INC and DEC are boostable */ |
192 | return X86_MODRM_REG(insn->modrm.bytes[0]) == 0b000 || |
193 | X86_MODRM_REG(insn->modrm.bytes[0]) == 0b001; |
194 | case 0xff: /* Grp5 */ |
195 | /* Only INC, DEC, and indirect JMP are boostable */ |
196 | return X86_MODRM_REG(insn->modrm.bytes[0]) == 0b000 || |
197 | X86_MODRM_REG(insn->modrm.bytes[0]) == 0b001 || |
198 | X86_MODRM_REG(insn->modrm.bytes[0]) == 0b100; |
199 | default: |
200 | return true; |
201 | } |
202 | } |
203 | |
204 | static unsigned long |
205 | __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) |
206 | { |
207 | struct kprobe *kp; |
208 | bool faddr; |
209 | |
210 | kp = get_kprobe(addr: (void *)addr); |
211 | faddr = ftrace_location(ip: addr) == addr; |
212 | /* |
213 | * Use the current code if it is not modified by Kprobe |
214 | * and it cannot be modified by ftrace. |
215 | */ |
216 | if (!kp && !faddr) |
217 | return addr; |
218 | |
219 | /* |
220 | * Basically, kp->ainsn.insn has an original instruction. |
221 | * However, RIP-relative instruction can not do single-stepping |
222 | * at different place, __copy_instruction() tweaks the displacement of |
223 | * that instruction. In that case, we can't recover the instruction |
224 | * from the kp->ainsn.insn. |
225 | * |
226 | * On the other hand, in case on normal Kprobe, kp->opcode has a copy |
227 | * of the first byte of the probed instruction, which is overwritten |
228 | * by int3. And the instruction at kp->addr is not modified by kprobes |
229 | * except for the first byte, we can recover the original instruction |
230 | * from it and kp->opcode. |
231 | * |
232 | * In case of Kprobes using ftrace, we do not have a copy of |
233 | * the original instruction. In fact, the ftrace location might |
234 | * be modified at anytime and even could be in an inconsistent state. |
235 | * Fortunately, we know that the original code is the ideal 5-byte |
236 | * long NOP. |
237 | */ |
238 | if (copy_from_kernel_nofault(dst: buf, src: (void *)addr, |
239 | MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) |
240 | return 0UL; |
241 | |
242 | if (faddr) |
243 | memcpy(buf, x86_nops[5], 5); |
244 | else |
245 | buf[0] = kp->opcode; |
246 | return (unsigned long)buf; |
247 | } |
248 | |
249 | /* |
250 | * Recover the probed instruction at addr for further analysis. |
251 | * Caller must lock kprobes by kprobe_mutex, or disable preemption |
252 | * for preventing to release referencing kprobes. |
253 | * Returns zero if the instruction can not get recovered (or access failed). |
254 | */ |
255 | unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr) |
256 | { |
257 | unsigned long __addr; |
258 | |
259 | __addr = __recover_optprobed_insn(buf, addr); |
260 | if (__addr != addr) |
261 | return __addr; |
262 | |
263 | return __recover_probed_insn(buf, addr); |
264 | } |
265 | |
266 | /* Check if insn is INT or UD */ |
267 | static inline bool is_exception_insn(struct insn *insn) |
268 | { |
269 | /* UD uses 0f escape */ |
270 | if (insn->opcode.bytes[0] == 0x0f) { |
271 | /* UD0 / UD1 / UD2 */ |
272 | return insn->opcode.bytes[1] == 0xff || |
273 | insn->opcode.bytes[1] == 0xb9 || |
274 | insn->opcode.bytes[1] == 0x0b; |
275 | } |
276 | |
277 | /* INT3 / INT n / INTO / INT1 */ |
278 | return insn->opcode.bytes[0] == 0xcc || |
279 | insn->opcode.bytes[0] == 0xcd || |
280 | insn->opcode.bytes[0] == 0xce || |
281 | insn->opcode.bytes[0] == 0xf1; |
282 | } |
283 | |
284 | /* |
285 | * Check if paddr is at an instruction boundary and that instruction can |
286 | * be probed |
287 | */ |
288 | static bool can_probe(unsigned long paddr) |
289 | { |
290 | unsigned long addr, __addr, offset = 0; |
291 | struct insn insn; |
292 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
293 | |
294 | if (!kallsyms_lookup_size_offset(addr: paddr, NULL, offset: &offset)) |
295 | return false; |
296 | |
297 | /* Decode instructions */ |
298 | addr = paddr - offset; |
299 | while (addr < paddr) { |
300 | /* |
301 | * Check if the instruction has been modified by another |
302 | * kprobe, in which case we replace the breakpoint by the |
303 | * original instruction in our buffer. |
304 | * Also, jump optimization will change the breakpoint to |
305 | * relative-jump. Since the relative-jump itself is |
306 | * normally used, we just go through if there is no kprobe. |
307 | */ |
308 | __addr = recover_probed_instruction(buf, addr); |
309 | if (!__addr) |
310 | return false; |
311 | |
312 | if (insn_decode_kernel(&insn, (void *)__addr) < 0) |
313 | return false; |
314 | |
315 | #ifdef CONFIG_KGDB |
316 | /* |
317 | * If there is a dynamically installed kgdb sw breakpoint, |
318 | * this function should not be probed. |
319 | */ |
320 | if (insn.opcode.bytes[0] == INT3_INSN_OPCODE && |
321 | kgdb_has_hit_break(addr)) |
322 | return false; |
323 | #endif |
324 | addr += insn.length; |
325 | } |
326 | |
327 | /* Check if paddr is at an instruction boundary */ |
328 | if (addr != paddr) |
329 | return false; |
330 | |
331 | __addr = recover_probed_instruction(buf, addr); |
332 | if (!__addr) |
333 | return false; |
334 | |
335 | if (insn_decode_kernel(&insn, (void *)__addr) < 0) |
336 | return false; |
337 | |
338 | /* INT and UD are special and should not be kprobed */ |
339 | if (is_exception_insn(insn: &insn)) |
340 | return false; |
341 | |
342 | if (IS_ENABLED(CONFIG_CFI_CLANG)) { |
343 | /* |
344 | * The compiler generates the following instruction sequence |
345 | * for indirect call checks and cfi.c decodes this; |
346 | * |
347 | *Â movl -<id>, %r10d ; 6 bytes |
348 | * addl -4(%reg), %r10d ; 4 bytes |
349 | * je .Ltmp1 ; 2 bytes |
350 | * ud2 ; <- regs->ip |
351 | * .Ltmp1: |
352 | * |
353 | * Also, these movl and addl are used for showing expected |
354 | * type. So those must not be touched. |
355 | */ |
356 | if (insn.opcode.value == 0xBA) |
357 | offset = 12; |
358 | else if (insn.opcode.value == 0x3) |
359 | offset = 6; |
360 | else |
361 | goto out; |
362 | |
363 | /* This movl/addl is used for decoding CFI. */ |
364 | if (is_cfi_trap(addr: addr + offset)) |
365 | return false; |
366 | } |
367 | |
368 | out: |
369 | return true; |
370 | } |
371 | |
372 | /* If x86 supports IBT (ENDBR) it must be skipped. */ |
373 | kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, |
374 | bool *on_func_entry) |
375 | { |
376 | u32 insn; |
377 | |
378 | /* |
379 | * Since 'addr' is not guaranteed to be safe to access, use |
380 | * copy_from_kernel_nofault() to read the instruction: |
381 | */ |
382 | if (copy_from_kernel_nofault(dst: &insn, src: (void *)addr, size: sizeof(u32))) |
383 | return NULL; |
384 | |
385 | if (is_endbr(val: insn)) { |
386 | *on_func_entry = !offset || offset == 4; |
387 | if (*on_func_entry) |
388 | offset = 4; |
389 | |
390 | } else { |
391 | *on_func_entry = !offset; |
392 | } |
393 | |
394 | return (kprobe_opcode_t *)(addr + offset); |
395 | } |
396 | |
397 | /* |
398 | * Copy an instruction with recovering modified instruction by kprobes |
399 | * and adjust the displacement if the instruction uses the %rip-relative |
400 | * addressing mode. Note that since @real will be the final place of copied |
401 | * instruction, displacement must be adjust by @real, not @dest. |
402 | * This returns the length of copied instruction, or 0 if it has an error. |
403 | */ |
404 | int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn) |
405 | { |
406 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
407 | unsigned long recovered_insn = recover_probed_instruction(buf, addr: (unsigned long)src); |
408 | int ret; |
409 | |
410 | if (!recovered_insn || !insn) |
411 | return 0; |
412 | |
413 | /* This can access kernel text if given address is not recovered */ |
414 | if (copy_from_kernel_nofault(dst: dest, src: (void *)recovered_insn, |
415 | MAX_INSN_SIZE)) |
416 | return 0; |
417 | |
418 | ret = insn_decode_kernel(insn, dest); |
419 | if (ret < 0) |
420 | return 0; |
421 | |
422 | /* We can not probe force emulate prefixed instruction */ |
423 | if (insn_has_emulate_prefix(insn)) |
424 | return 0; |
425 | |
426 | /* Another subsystem puts a breakpoint, failed to recover */ |
427 | if (insn->opcode.bytes[0] == INT3_INSN_OPCODE) |
428 | return 0; |
429 | |
430 | /* We should not singlestep on the exception masking instructions */ |
431 | if (insn_masking_exception(insn)) |
432 | return 0; |
433 | |
434 | #ifdef CONFIG_X86_64 |
435 | /* Only x86_64 has RIP relative instructions */ |
436 | if (insn_rip_relative(insn)) { |
437 | s64 newdisp; |
438 | u8 *disp; |
439 | /* |
440 | * The copied instruction uses the %rip-relative addressing |
441 | * mode. Adjust the displacement for the difference between |
442 | * the original location of this instruction and the location |
443 | * of the copy that will actually be run. The tricky bit here |
444 | * is making sure that the sign extension happens correctly in |
445 | * this calculation, since we need a signed 32-bit result to |
446 | * be sign-extended to 64 bits when it's added to the %rip |
447 | * value and yield the same 64-bit result that the sign- |
448 | * extension of the original signed 32-bit displacement would |
449 | * have given. |
450 | */ |
451 | newdisp = (u8 *) src + (s64) insn->displacement.value |
452 | - (u8 *) real; |
453 | if ((s64) (s32) newdisp != newdisp) { |
454 | pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n" , newdisp); |
455 | return 0; |
456 | } |
457 | disp = (u8 *) dest + insn_offset_displacement(insn); |
458 | *(s32 *) disp = (s32) newdisp; |
459 | } |
460 | #endif |
461 | return insn->length; |
462 | } |
463 | |
464 | /* Prepare reljump or int3 right after instruction */ |
465 | static int prepare_singlestep(kprobe_opcode_t *buf, struct kprobe *p, |
466 | struct insn *insn) |
467 | { |
468 | int len = insn->length; |
469 | |
470 | if (!IS_ENABLED(CONFIG_PREEMPTION) && |
471 | !p->post_handler && can_boost(insn, addr: p->addr) && |
472 | MAX_INSN_SIZE - len >= JMP32_INSN_SIZE) { |
473 | /* |
474 | * These instructions can be executed directly if it |
475 | * jumps back to correct address. |
476 | */ |
477 | synthesize_reljump(dest: buf + len, from: p->ainsn.insn + len, |
478 | to: p->addr + insn->length); |
479 | len += JMP32_INSN_SIZE; |
480 | p->ainsn.boostable = 1; |
481 | } else { |
482 | /* Otherwise, put an int3 for trapping singlestep */ |
483 | if (MAX_INSN_SIZE - len < INT3_INSN_SIZE) |
484 | return -ENOSPC; |
485 | |
486 | buf[len] = INT3_INSN_OPCODE; |
487 | len += INT3_INSN_SIZE; |
488 | } |
489 | |
490 | return len; |
491 | } |
492 | |
493 | /* Make page to RO mode when allocate it */ |
494 | void *alloc_insn_page(void) |
495 | { |
496 | void *page; |
497 | |
498 | page = module_alloc(PAGE_SIZE); |
499 | if (!page) |
500 | return NULL; |
501 | |
502 | /* |
503 | * TODO: Once additional kernel code protection mechanisms are set, ensure |
504 | * that the page was not maliciously altered and it is still zeroed. |
505 | */ |
506 | set_memory_rox(addr: (unsigned long)page, numpages: 1); |
507 | |
508 | return page; |
509 | } |
510 | |
511 | /* Kprobe x86 instruction emulation - only regs->ip or IF flag modifiers */ |
512 | |
513 | static void kprobe_emulate_ifmodifiers(struct kprobe *p, struct pt_regs *regs) |
514 | { |
515 | switch (p->ainsn.opcode) { |
516 | case 0xfa: /* cli */ |
517 | regs->flags &= ~(X86_EFLAGS_IF); |
518 | break; |
519 | case 0xfb: /* sti */ |
520 | regs->flags |= X86_EFLAGS_IF; |
521 | break; |
522 | case 0x9c: /* pushf */ |
523 | int3_emulate_push(regs, val: regs->flags); |
524 | break; |
525 | case 0x9d: /* popf */ |
526 | regs->flags = int3_emulate_pop(regs); |
527 | break; |
528 | } |
529 | regs->ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; |
530 | } |
531 | NOKPROBE_SYMBOL(kprobe_emulate_ifmodifiers); |
532 | |
533 | static void kprobe_emulate_ret(struct kprobe *p, struct pt_regs *regs) |
534 | { |
535 | int3_emulate_ret(regs); |
536 | } |
537 | NOKPROBE_SYMBOL(kprobe_emulate_ret); |
538 | |
539 | static void kprobe_emulate_call(struct kprobe *p, struct pt_regs *regs) |
540 | { |
541 | unsigned long func = regs->ip - INT3_INSN_SIZE + p->ainsn.size; |
542 | |
543 | func += p->ainsn.rel32; |
544 | int3_emulate_call(regs, func); |
545 | } |
546 | NOKPROBE_SYMBOL(kprobe_emulate_call); |
547 | |
548 | static void kprobe_emulate_jmp(struct kprobe *p, struct pt_regs *regs) |
549 | { |
550 | unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; |
551 | |
552 | ip += p->ainsn.rel32; |
553 | int3_emulate_jmp(regs, ip); |
554 | } |
555 | NOKPROBE_SYMBOL(kprobe_emulate_jmp); |
556 | |
557 | static void kprobe_emulate_jcc(struct kprobe *p, struct pt_regs *regs) |
558 | { |
559 | unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; |
560 | |
561 | int3_emulate_jcc(regs, cc: p->ainsn.jcc.type, ip, disp: p->ainsn.rel32); |
562 | } |
563 | NOKPROBE_SYMBOL(kprobe_emulate_jcc); |
564 | |
565 | static void kprobe_emulate_loop(struct kprobe *p, struct pt_regs *regs) |
566 | { |
567 | unsigned long ip = regs->ip - INT3_INSN_SIZE + p->ainsn.size; |
568 | bool match; |
569 | |
570 | if (p->ainsn.loop.type != 3) { /* LOOP* */ |
571 | if (p->ainsn.loop.asize == 32) |
572 | match = ((*(u32 *)®s->cx)--) != 0; |
573 | #ifdef CONFIG_X86_64 |
574 | else if (p->ainsn.loop.asize == 64) |
575 | match = ((*(u64 *)®s->cx)--) != 0; |
576 | #endif |
577 | else |
578 | match = ((*(u16 *)®s->cx)--) != 0; |
579 | } else { /* JCXZ */ |
580 | if (p->ainsn.loop.asize == 32) |
581 | match = *(u32 *)(®s->cx) == 0; |
582 | #ifdef CONFIG_X86_64 |
583 | else if (p->ainsn.loop.asize == 64) |
584 | match = *(u64 *)(®s->cx) == 0; |
585 | #endif |
586 | else |
587 | match = *(u16 *)(®s->cx) == 0; |
588 | } |
589 | |
590 | if (p->ainsn.loop.type == 0) /* LOOPNE */ |
591 | match = match && !(regs->flags & X86_EFLAGS_ZF); |
592 | else if (p->ainsn.loop.type == 1) /* LOOPE */ |
593 | match = match && (regs->flags & X86_EFLAGS_ZF); |
594 | |
595 | if (match) |
596 | ip += p->ainsn.rel32; |
597 | int3_emulate_jmp(regs, ip); |
598 | } |
599 | NOKPROBE_SYMBOL(kprobe_emulate_loop); |
600 | |
601 | static const int addrmode_regoffs[] = { |
602 | offsetof(struct pt_regs, ax), |
603 | offsetof(struct pt_regs, cx), |
604 | offsetof(struct pt_regs, dx), |
605 | offsetof(struct pt_regs, bx), |
606 | offsetof(struct pt_regs, sp), |
607 | offsetof(struct pt_regs, bp), |
608 | offsetof(struct pt_regs, si), |
609 | offsetof(struct pt_regs, di), |
610 | #ifdef CONFIG_X86_64 |
611 | offsetof(struct pt_regs, r8), |
612 | offsetof(struct pt_regs, r9), |
613 | offsetof(struct pt_regs, r10), |
614 | offsetof(struct pt_regs, r11), |
615 | offsetof(struct pt_regs, r12), |
616 | offsetof(struct pt_regs, r13), |
617 | offsetof(struct pt_regs, r14), |
618 | offsetof(struct pt_regs, r15), |
619 | #endif |
620 | }; |
621 | |
622 | static void kprobe_emulate_call_indirect(struct kprobe *p, struct pt_regs *regs) |
623 | { |
624 | unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg]; |
625 | |
626 | int3_emulate_push(regs, val: regs->ip - INT3_INSN_SIZE + p->ainsn.size); |
627 | int3_emulate_jmp(regs, ip: regs_get_register(regs, offset: offs)); |
628 | } |
629 | NOKPROBE_SYMBOL(kprobe_emulate_call_indirect); |
630 | |
631 | static void kprobe_emulate_jmp_indirect(struct kprobe *p, struct pt_regs *regs) |
632 | { |
633 | unsigned long offs = addrmode_regoffs[p->ainsn.indirect.reg]; |
634 | |
635 | int3_emulate_jmp(regs, ip: regs_get_register(regs, offset: offs)); |
636 | } |
637 | NOKPROBE_SYMBOL(kprobe_emulate_jmp_indirect); |
638 | |
639 | static int prepare_emulation(struct kprobe *p, struct insn *insn) |
640 | { |
641 | insn_byte_t opcode = insn->opcode.bytes[0]; |
642 | |
643 | switch (opcode) { |
644 | case 0xfa: /* cli */ |
645 | case 0xfb: /* sti */ |
646 | case 0x9c: /* pushfl */ |
647 | case 0x9d: /* popf/popfd */ |
648 | /* |
649 | * IF modifiers must be emulated since it will enable interrupt while |
650 | * int3 single stepping. |
651 | */ |
652 | p->ainsn.emulate_op = kprobe_emulate_ifmodifiers; |
653 | p->ainsn.opcode = opcode; |
654 | break; |
655 | case 0xc2: /* ret/lret */ |
656 | case 0xc3: |
657 | case 0xca: |
658 | case 0xcb: |
659 | p->ainsn.emulate_op = kprobe_emulate_ret; |
660 | break; |
661 | case 0x9a: /* far call absolute -- segment is not supported */ |
662 | case 0xea: /* far jmp absolute -- segment is not supported */ |
663 | case 0xcc: /* int3 */ |
664 | case 0xcf: /* iret -- in-kernel IRET is not supported */ |
665 | return -EOPNOTSUPP; |
666 | break; |
667 | case 0xe8: /* near call relative */ |
668 | p->ainsn.emulate_op = kprobe_emulate_call; |
669 | if (insn->immediate.nbytes == 2) |
670 | p->ainsn.rel32 = *(s16 *)&insn->immediate.value; |
671 | else |
672 | p->ainsn.rel32 = *(s32 *)&insn->immediate.value; |
673 | break; |
674 | case 0xeb: /* short jump relative */ |
675 | case 0xe9: /* near jump relative */ |
676 | p->ainsn.emulate_op = kprobe_emulate_jmp; |
677 | if (insn->immediate.nbytes == 1) |
678 | p->ainsn.rel32 = *(s8 *)&insn->immediate.value; |
679 | else if (insn->immediate.nbytes == 2) |
680 | p->ainsn.rel32 = *(s16 *)&insn->immediate.value; |
681 | else |
682 | p->ainsn.rel32 = *(s32 *)&insn->immediate.value; |
683 | break; |
684 | case 0x70 ... 0x7f: |
685 | /* 1 byte conditional jump */ |
686 | p->ainsn.emulate_op = kprobe_emulate_jcc; |
687 | p->ainsn.jcc.type = opcode & 0xf; |
688 | p->ainsn.rel32 = insn->immediate.value; |
689 | break; |
690 | case 0x0f: |
691 | opcode = insn->opcode.bytes[1]; |
692 | if ((opcode & 0xf0) == 0x80) { |
693 | /* 2 bytes Conditional Jump */ |
694 | p->ainsn.emulate_op = kprobe_emulate_jcc; |
695 | p->ainsn.jcc.type = opcode & 0xf; |
696 | if (insn->immediate.nbytes == 2) |
697 | p->ainsn.rel32 = *(s16 *)&insn->immediate.value; |
698 | else |
699 | p->ainsn.rel32 = *(s32 *)&insn->immediate.value; |
700 | } else if (opcode == 0x01 && |
701 | X86_MODRM_REG(insn->modrm.bytes[0]) == 0 && |
702 | X86_MODRM_MOD(insn->modrm.bytes[0]) == 3) { |
703 | /* VM extensions - not supported */ |
704 | return -EOPNOTSUPP; |
705 | } |
706 | break; |
707 | case 0xe0: /* Loop NZ */ |
708 | case 0xe1: /* Loop */ |
709 | case 0xe2: /* Loop */ |
710 | case 0xe3: /* J*CXZ */ |
711 | p->ainsn.emulate_op = kprobe_emulate_loop; |
712 | p->ainsn.loop.type = opcode & 0x3; |
713 | p->ainsn.loop.asize = insn->addr_bytes * 8; |
714 | p->ainsn.rel32 = *(s8 *)&insn->immediate.value; |
715 | break; |
716 | case 0xff: |
717 | /* |
718 | * Since the 0xff is an extended group opcode, the instruction |
719 | * is determined by the MOD/RM byte. |
720 | */ |
721 | opcode = insn->modrm.bytes[0]; |
722 | switch (X86_MODRM_REG(opcode)) { |
723 | case 0b010: /* FF /2, call near, absolute indirect */ |
724 | p->ainsn.emulate_op = kprobe_emulate_call_indirect; |
725 | break; |
726 | case 0b100: /* FF /4, jmp near, absolute indirect */ |
727 | p->ainsn.emulate_op = kprobe_emulate_jmp_indirect; |
728 | break; |
729 | case 0b011: /* FF /3, call far, absolute indirect */ |
730 | case 0b101: /* FF /5, jmp far, absolute indirect */ |
731 | return -EOPNOTSUPP; |
732 | } |
733 | |
734 | if (!p->ainsn.emulate_op) |
735 | break; |
736 | |
737 | if (insn->addr_bytes != sizeof(unsigned long)) |
738 | return -EOPNOTSUPP; /* Don't support different size */ |
739 | if (X86_MODRM_MOD(opcode) != 3) |
740 | return -EOPNOTSUPP; /* TODO: support memory addressing */ |
741 | |
742 | p->ainsn.indirect.reg = X86_MODRM_RM(opcode); |
743 | #ifdef CONFIG_X86_64 |
744 | if (X86_REX_B(insn->rex_prefix.value)) |
745 | p->ainsn.indirect.reg += 8; |
746 | #endif |
747 | break; |
748 | default: |
749 | break; |
750 | } |
751 | p->ainsn.size = insn->length; |
752 | |
753 | return 0; |
754 | } |
755 | |
756 | static int arch_copy_kprobe(struct kprobe *p) |
757 | { |
758 | struct insn insn; |
759 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
760 | int ret, len; |
761 | |
762 | /* Copy an instruction with recovering if other optprobe modifies it.*/ |
763 | len = __copy_instruction(dest: buf, src: p->addr, real: p->ainsn.insn, insn: &insn); |
764 | if (!len) |
765 | return -EINVAL; |
766 | |
767 | /* Analyze the opcode and setup emulate functions */ |
768 | ret = prepare_emulation(p, insn: &insn); |
769 | if (ret < 0) |
770 | return ret; |
771 | |
772 | /* Add int3 for single-step or booster jmp */ |
773 | len = prepare_singlestep(buf, p, insn: &insn); |
774 | if (len < 0) |
775 | return len; |
776 | |
777 | /* Also, displacement change doesn't affect the first byte */ |
778 | p->opcode = buf[0]; |
779 | |
780 | p->ainsn.tp_len = len; |
781 | perf_event_text_poke(addr: p->ainsn.insn, NULL, old_len: 0, new_bytes: buf, new_len: len); |
782 | |
783 | /* OK, write back the instruction(s) into ROX insn buffer */ |
784 | text_poke(addr: p->ainsn.insn, opcode: buf, len); |
785 | |
786 | return 0; |
787 | } |
788 | |
789 | int arch_prepare_kprobe(struct kprobe *p) |
790 | { |
791 | int ret; |
792 | |
793 | if (alternatives_text_reserved(start: p->addr, end: p->addr)) |
794 | return -EINVAL; |
795 | |
796 | if (!can_probe(paddr: (unsigned long)p->addr)) |
797 | return -EILSEQ; |
798 | |
799 | memset(&p->ainsn, 0, sizeof(p->ainsn)); |
800 | |
801 | /* insn: must be on special executable page on x86. */ |
802 | p->ainsn.insn = get_insn_slot(); |
803 | if (!p->ainsn.insn) |
804 | return -ENOMEM; |
805 | |
806 | ret = arch_copy_kprobe(p); |
807 | if (ret) { |
808 | free_insn_slot(slot: p->ainsn.insn, dirty: 0); |
809 | p->ainsn.insn = NULL; |
810 | } |
811 | |
812 | return ret; |
813 | } |
814 | |
815 | void arch_arm_kprobe(struct kprobe *p) |
816 | { |
817 | u8 int3 = INT3_INSN_OPCODE; |
818 | |
819 | text_poke(addr: p->addr, opcode: &int3, len: 1); |
820 | text_poke_sync(); |
821 | perf_event_text_poke(addr: p->addr, old_bytes: &p->opcode, old_len: 1, new_bytes: &int3, new_len: 1); |
822 | } |
823 | |
824 | void arch_disarm_kprobe(struct kprobe *p) |
825 | { |
826 | u8 int3 = INT3_INSN_OPCODE; |
827 | |
828 | perf_event_text_poke(addr: p->addr, old_bytes: &int3, old_len: 1, new_bytes: &p->opcode, new_len: 1); |
829 | text_poke(addr: p->addr, opcode: &p->opcode, len: 1); |
830 | text_poke_sync(); |
831 | } |
832 | |
833 | void arch_remove_kprobe(struct kprobe *p) |
834 | { |
835 | if (p->ainsn.insn) { |
836 | /* Record the perf event before freeing the slot */ |
837 | perf_event_text_poke(addr: p->ainsn.insn, old_bytes: p->ainsn.insn, |
838 | old_len: p->ainsn.tp_len, NULL, new_len: 0); |
839 | free_insn_slot(slot: p->ainsn.insn, dirty: p->ainsn.boostable); |
840 | p->ainsn.insn = NULL; |
841 | } |
842 | } |
843 | |
844 | static nokprobe_inline void |
845 | save_previous_kprobe(struct kprobe_ctlblk *kcb) |
846 | { |
847 | kcb->prev_kprobe.kp = kprobe_running(); |
848 | kcb->prev_kprobe.status = kcb->kprobe_status; |
849 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
850 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; |
851 | } |
852 | |
853 | static nokprobe_inline void |
854 | restore_previous_kprobe(struct kprobe_ctlblk *kcb) |
855 | { |
856 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
857 | kcb->kprobe_status = kcb->prev_kprobe.status; |
858 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
859 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; |
860 | } |
861 | |
862 | static nokprobe_inline void |
863 | set_current_kprobe(struct kprobe *p, struct pt_regs *regs, |
864 | struct kprobe_ctlblk *kcb) |
865 | { |
866 | __this_cpu_write(current_kprobe, p); |
867 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
868 | = (regs->flags & X86_EFLAGS_IF); |
869 | } |
870 | |
871 | static void kprobe_post_process(struct kprobe *cur, struct pt_regs *regs, |
872 | struct kprobe_ctlblk *kcb) |
873 | { |
874 | /* Restore back the original saved kprobes variables and continue. */ |
875 | if (kcb->kprobe_status == KPROBE_REENTER) { |
876 | /* This will restore both kcb and current_kprobe */ |
877 | restore_previous_kprobe(kcb); |
878 | } else { |
879 | /* |
880 | * Always update the kcb status because |
881 | * reset_curent_kprobe() doesn't update kcb. |
882 | */ |
883 | kcb->kprobe_status = KPROBE_HIT_SSDONE; |
884 | if (cur->post_handler) |
885 | cur->post_handler(cur, regs, 0); |
886 | reset_current_kprobe(); |
887 | } |
888 | } |
889 | NOKPROBE_SYMBOL(kprobe_post_process); |
890 | |
891 | static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
892 | struct kprobe_ctlblk *kcb, int reenter) |
893 | { |
894 | if (setup_detour_execution(p, regs, reenter)) |
895 | return; |
896 | |
897 | #if !defined(CONFIG_PREEMPTION) |
898 | if (p->ainsn.boostable) { |
899 | /* Boost up -- we can execute copied instructions directly */ |
900 | if (!reenter) |
901 | reset_current_kprobe(); |
902 | /* |
903 | * Reentering boosted probe doesn't reset current_kprobe, |
904 | * nor set current_kprobe, because it doesn't use single |
905 | * stepping. |
906 | */ |
907 | regs->ip = (unsigned long)p->ainsn.insn; |
908 | return; |
909 | } |
910 | #endif |
911 | if (reenter) { |
912 | save_previous_kprobe(kcb); |
913 | set_current_kprobe(p, regs, kcb); |
914 | kcb->kprobe_status = KPROBE_REENTER; |
915 | } else |
916 | kcb->kprobe_status = KPROBE_HIT_SS; |
917 | |
918 | if (p->ainsn.emulate_op) { |
919 | p->ainsn.emulate_op(p, regs); |
920 | kprobe_post_process(cur: p, regs, kcb); |
921 | return; |
922 | } |
923 | |
924 | /* Disable interrupt, and set ip register on trampoline */ |
925 | regs->flags &= ~X86_EFLAGS_IF; |
926 | regs->ip = (unsigned long)p->ainsn.insn; |
927 | } |
928 | NOKPROBE_SYMBOL(setup_singlestep); |
929 | |
930 | /* |
931 | * Called after single-stepping. p->addr is the address of the |
932 | * instruction whose first byte has been replaced by the "int3" |
933 | * instruction. To avoid the SMP problems that can occur when we |
934 | * temporarily put back the original opcode to single-step, we |
935 | * single-stepped a copy of the instruction. The address of this |
936 | * copy is p->ainsn.insn. We also doesn't use trap, but "int3" again |
937 | * right after the copied instruction. |
938 | * Different from the trap single-step, "int3" single-step can not |
939 | * handle the instruction which changes the ip register, e.g. jmp, |
940 | * call, conditional jmp, and the instructions which changes the IF |
941 | * flags because interrupt must be disabled around the single-stepping. |
942 | * Such instructions are software emulated, but others are single-stepped |
943 | * using "int3". |
944 | * |
945 | * When the 2nd "int3" handled, the regs->ip and regs->flags needs to |
946 | * be adjusted, so that we can resume execution on correct code. |
947 | */ |
948 | static void resume_singlestep(struct kprobe *p, struct pt_regs *regs, |
949 | struct kprobe_ctlblk *kcb) |
950 | { |
951 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; |
952 | unsigned long orig_ip = (unsigned long)p->addr; |
953 | |
954 | /* Restore saved interrupt flag and ip register */ |
955 | regs->flags |= kcb->kprobe_saved_flags; |
956 | /* Note that regs->ip is executed int3 so must be a step back */ |
957 | regs->ip += (orig_ip - copy_ip) - INT3_INSN_SIZE; |
958 | } |
959 | NOKPROBE_SYMBOL(resume_singlestep); |
960 | |
961 | /* |
962 | * We have reentered the kprobe_handler(), since another probe was hit while |
963 | * within the handler. We save the original kprobes variables and just single |
964 | * step on the instruction of the new probe without calling any user handlers. |
965 | */ |
966 | static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
967 | struct kprobe_ctlblk *kcb) |
968 | { |
969 | switch (kcb->kprobe_status) { |
970 | case KPROBE_HIT_SSDONE: |
971 | case KPROBE_HIT_ACTIVE: |
972 | case KPROBE_HIT_SS: |
973 | kprobes_inc_nmissed_count(p); |
974 | setup_singlestep(p, regs, kcb, reenter: 1); |
975 | break; |
976 | case KPROBE_REENTER: |
977 | /* A probe has been hit in the codepath leading up to, or just |
978 | * after, single-stepping of a probed instruction. This entire |
979 | * codepath should strictly reside in .kprobes.text section. |
980 | * Raise a BUG or we'll continue in an endless reentering loop |
981 | * and eventually a stack overflow. |
982 | */ |
983 | pr_err("Unrecoverable kprobe detected.\n" ); |
984 | dump_kprobe(kp: p); |
985 | BUG(); |
986 | default: |
987 | /* impossible cases */ |
988 | WARN_ON(1); |
989 | return 0; |
990 | } |
991 | |
992 | return 1; |
993 | } |
994 | NOKPROBE_SYMBOL(reenter_kprobe); |
995 | |
996 | static nokprobe_inline int kprobe_is_ss(struct kprobe_ctlblk *kcb) |
997 | { |
998 | return (kcb->kprobe_status == KPROBE_HIT_SS || |
999 | kcb->kprobe_status == KPROBE_REENTER); |
1000 | } |
1001 | |
1002 | /* |
1003 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they |
1004 | * remain disabled throughout this function. |
1005 | */ |
1006 | int kprobe_int3_handler(struct pt_regs *regs) |
1007 | { |
1008 | kprobe_opcode_t *addr; |
1009 | struct kprobe *p; |
1010 | struct kprobe_ctlblk *kcb; |
1011 | |
1012 | if (user_mode(regs)) |
1013 | return 0; |
1014 | |
1015 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
1016 | /* |
1017 | * We don't want to be preempted for the entire duration of kprobe |
1018 | * processing. Since int3 and debug trap disables irqs and we clear |
1019 | * IF while singlestepping, it must be no preemptible. |
1020 | */ |
1021 | |
1022 | kcb = get_kprobe_ctlblk(); |
1023 | p = get_kprobe(addr); |
1024 | |
1025 | if (p) { |
1026 | if (kprobe_running()) { |
1027 | if (reenter_kprobe(p, regs, kcb)) |
1028 | return 1; |
1029 | } else { |
1030 | set_current_kprobe(p, regs, kcb); |
1031 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
1032 | |
1033 | /* |
1034 | * If we have no pre-handler or it returned 0, we |
1035 | * continue with normal processing. If we have a |
1036 | * pre-handler and it returned non-zero, that means |
1037 | * user handler setup registers to exit to another |
1038 | * instruction, we must skip the single stepping. |
1039 | */ |
1040 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
1041 | setup_singlestep(p, regs, kcb, reenter: 0); |
1042 | else |
1043 | reset_current_kprobe(); |
1044 | return 1; |
1045 | } |
1046 | } else if (kprobe_is_ss(kcb)) { |
1047 | p = kprobe_running(); |
1048 | if ((unsigned long)p->ainsn.insn < regs->ip && |
1049 | (unsigned long)p->ainsn.insn + MAX_INSN_SIZE > regs->ip) { |
1050 | /* Most provably this is the second int3 for singlestep */ |
1051 | resume_singlestep(p, regs, kcb); |
1052 | kprobe_post_process(cur: p, regs, kcb); |
1053 | return 1; |
1054 | } |
1055 | } /* else: not a kprobe fault; let the kernel handle it */ |
1056 | |
1057 | return 0; |
1058 | } |
1059 | NOKPROBE_SYMBOL(kprobe_int3_handler); |
1060 | |
1061 | int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1062 | { |
1063 | struct kprobe *cur = kprobe_running(); |
1064 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1065 | |
1066 | if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) { |
1067 | /* This must happen on single-stepping */ |
1068 | WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS && |
1069 | kcb->kprobe_status != KPROBE_REENTER); |
1070 | /* |
1071 | * We are here because the instruction being single |
1072 | * stepped caused a page fault. We reset the current |
1073 | * kprobe and the ip points back to the probe address |
1074 | * and allow the page fault handler to continue as a |
1075 | * normal page fault. |
1076 | */ |
1077 | regs->ip = (unsigned long)cur->addr; |
1078 | |
1079 | /* |
1080 | * If the IF flag was set before the kprobe hit, |
1081 | * don't touch it: |
1082 | */ |
1083 | regs->flags |= kcb->kprobe_old_flags; |
1084 | |
1085 | if (kcb->kprobe_status == KPROBE_REENTER) |
1086 | restore_previous_kprobe(kcb); |
1087 | else |
1088 | reset_current_kprobe(); |
1089 | } |
1090 | |
1091 | return 0; |
1092 | } |
1093 | NOKPROBE_SYMBOL(kprobe_fault_handler); |
1094 | |
1095 | int __init arch_populate_kprobe_blacklist(void) |
1096 | { |
1097 | return kprobe_add_area_blacklist(start: (unsigned long)__entry_text_start, |
1098 | end: (unsigned long)__entry_text_end); |
1099 | } |
1100 | |
1101 | int __init arch_init_kprobes(void) |
1102 | { |
1103 | return 0; |
1104 | } |
1105 | |
1106 | int arch_trampoline_kprobe(struct kprobe *p) |
1107 | { |
1108 | return 0; |
1109 | } |
1110 | |