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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> |
b17b0153 | 48 | #include <linux/sched/debug.h> |
744c193e | 49 | #include <linux/extable.h> |
1eeb66a1 | 50 | #include <linux/kdebug.h> |
b46b3d70 | 51 | #include <linux/kallsyms.h> |
c0f7ac3a | 52 | #include <linux/ftrace.h> |
87aaff2a | 53 | #include <linux/frame.h> |
9f7d416c | 54 | #include <linux/kasan.h> |
c93f5cf5 | 55 | #include <linux/moduleloader.h> |
9ec4b1f3 | 56 | |
35de5b06 | 57 | #include <asm/text-patching.h> |
8533bbe9 MH |
58 | #include <asm/cacheflush.h> |
59 | #include <asm/desc.h> | |
1da177e4 | 60 | #include <asm/pgtable.h> |
7c0f6ba6 | 61 | #include <linux/uaccess.h> |
19d36ccd | 62 | #include <asm/alternative.h> |
b46b3d70 | 63 | #include <asm/insn.h> |
62edab90 | 64 | #include <asm/debugreg.h> |
e6ccbff0 | 65 | #include <asm/set_memory.h> |
1da177e4 | 66 | |
f684199f | 67 | #include "common.h" |
3f33ab1c | 68 | |
1da177e4 LT |
69 | void jprobe_return_end(void); |
70 | ||
e7a510f9 AM |
71 | DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; |
72 | DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); | |
1da177e4 | 73 | |
98272ed0 | 74 | #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs)) |
8533bbe9 MH |
75 | |
76 | #define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\ | |
77 | (((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) | \ | |
78 | (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) | \ | |
79 | (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) | \ | |
80 | (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf)) \ | |
81 | << (row % 32)) | |
82 | /* | |
83 | * Undefined/reserved opcodes, conditional jump, Opcode Extension | |
84 | * Groups, and some special opcodes can not boost. | |
7115e3fc LT |
85 | * This is non-const and volatile to keep gcc from statically |
86 | * optimizing it out, as variable_test_bit makes gcc think only | |
f684199f | 87 | * *(unsigned long*) is used. |
8533bbe9 | 88 | */ |
7115e3fc | 89 | static volatile u32 twobyte_is_boostable[256 / 32] = { |
8533bbe9 MH |
90 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ |
91 | /* ---------------------------------------------- */ | |
92 | W(0x00, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0) | /* 00 */ | |
b7e37567 | 93 | W(0x10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1) , /* 10 */ |
8533bbe9 MH |
94 | W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 20 */ |
95 | W(0x30, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */ | |
96 | W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */ | |
97 | W(0x50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 50 */ | |
98 | W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1) | /* 60 */ | |
99 | W(0x70, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */ | |
100 | W(0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 80 */ | |
101 | W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */ | |
102 | W(0xa0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* a0 */ | |
103 | W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1) , /* b0 */ | |
104 | W(0xc0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */ | |
105 | W(0xd0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) , /* d0 */ | |
106 | W(0xe0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1) | /* e0 */ | |
107 | W(0xf0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0) /* f0 */ | |
108 | /* ----------------------------------------------- */ | |
109 | /* 0 1 2 3 4 5 6 7 8 9 a b c d e f */ | |
110 | }; | |
8533bbe9 MH |
111 | #undef W |
112 | ||
f438d914 MH |
113 | struct kretprobe_blackpoint kretprobe_blacklist[] = { |
114 | {"__switch_to", }, /* This function switches only current task, but | |
115 | doesn't switch kernel stack.*/ | |
116 | {NULL, NULL} /* Terminator */ | |
117 | }; | |
3f33ab1c | 118 | |
f438d914 MH |
119 | const int kretprobe_blacklist_size = ARRAY_SIZE(kretprobe_blacklist); |
120 | ||
9326638c MH |
121 | static nokprobe_inline void |
122 | __synthesize_relative_insn(void *from, void *to, u8 op) | |
aa470140 | 123 | { |
c0f7ac3a MH |
124 | struct __arch_relative_insn { |
125 | u8 op; | |
aa470140 | 126 | s32 raddr; |
f684199f | 127 | } __packed *insn; |
c0f7ac3a MH |
128 | |
129 | insn = (struct __arch_relative_insn *)from; | |
130 | insn->raddr = (s32)((long)(to) - ((long)(from) + 5)); | |
131 | insn->op = op; | |
132 | } | |
133 | ||
134 | /* Insert a jump instruction at address 'from', which jumps to address 'to'.*/ | |
9326638c | 135 | void synthesize_reljump(void *from, void *to) |
c0f7ac3a MH |
136 | { |
137 | __synthesize_relative_insn(from, to, RELATIVEJUMP_OPCODE); | |
aa470140 | 138 | } |
9326638c | 139 | NOKPROBE_SYMBOL(synthesize_reljump); |
aa470140 | 140 | |
3f33ab1c | 141 | /* Insert a call instruction at address 'from', which calls address 'to'.*/ |
9326638c | 142 | void synthesize_relcall(void *from, void *to) |
3f33ab1c MH |
143 | { |
144 | __synthesize_relative_insn(from, to, RELATIVECALL_OPCODE); | |
145 | } | |
9326638c | 146 | NOKPROBE_SYMBOL(synthesize_relcall); |
3f33ab1c | 147 | |
9930927f | 148 | /* |
567a9fd8 | 149 | * Skip the prefixes of the instruction. |
9930927f | 150 | */ |
9326638c | 151 | static kprobe_opcode_t *skip_prefixes(kprobe_opcode_t *insn) |
9930927f | 152 | { |
567a9fd8 MH |
153 | insn_attr_t attr; |
154 | ||
155 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
156 | while (inat_is_legacy_prefix(attr)) { | |
157 | insn++; | |
158 | attr = inat_get_opcode_attribute((insn_byte_t)*insn); | |
159 | } | |
9930927f | 160 | #ifdef CONFIG_X86_64 |
567a9fd8 MH |
161 | if (inat_is_rex_prefix(attr)) |
162 | insn++; | |
9930927f | 163 | #endif |
567a9fd8 | 164 | return insn; |
9930927f | 165 | } |
9326638c | 166 | NOKPROBE_SYMBOL(skip_prefixes); |
9930927f | 167 | |
aa470140 | 168 | /* |
a8d11cd0 | 169 | * Returns non-zero if INSN is boostable. |
d6be29b8 | 170 | * RIP relative instructions are adjusted at copying time in 64 bits mode |
aa470140 | 171 | */ |
a8d11cd0 | 172 | int can_boost(struct insn *insn, void *addr) |
aa470140 | 173 | { |
aa470140 | 174 | kprobe_opcode_t opcode; |
aa470140 | 175 | |
75013fb1 | 176 | if (search_exception_tables((unsigned long)addr)) |
30390880 MH |
177 | return 0; /* Page fault may occur on this address. */ |
178 | ||
aa470140 | 179 | /* 2nd-byte opcode */ |
a8d11cd0 MH |
180 | if (insn->opcode.nbytes == 2) |
181 | return test_bit(insn->opcode.bytes[1], | |
8533bbe9 | 182 | (unsigned long *)twobyte_is_boostable); |
17880e4d | 183 | |
a8d11cd0 | 184 | if (insn->opcode.nbytes != 1) |
17880e4d MH |
185 | return 0; |
186 | ||
187 | /* Can't boost Address-size override prefix */ | |
a8d11cd0 | 188 | if (unlikely(inat_is_address_size_prefix(insn->attr))) |
17880e4d MH |
189 | return 0; |
190 | ||
a8d11cd0 | 191 | opcode = insn->opcode.bytes[0]; |
aa470140 MH |
192 | |
193 | switch (opcode & 0xf0) { | |
aa470140 | 194 | case 0x60: |
17880e4d MH |
195 | /* can't boost "bound" */ |
196 | return (opcode != 0x62); | |
aa470140 MH |
197 | case 0x70: |
198 | return 0; /* can't boost conditional jump */ | |
bd0b9067 MH |
199 | case 0x90: |
200 | return opcode != 0x9a; /* can't boost call far */ | |
aa470140 MH |
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: | |
aa470140 MH |
211 | /* clear and set flags are boostable */ |
212 | return (opcode == 0xf5 || (0xf7 < opcode && opcode < 0xfe)); | |
213 | default: | |
aa470140 MH |
214 | /* CS override prefix and call are not boostable */ |
215 | return (opcode != 0x2e && opcode != 0x9a); | |
216 | } | |
217 | } | |
218 | ||
3f33ab1c MH |
219 | static unsigned long |
220 | __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) | |
b46b3d70 MH |
221 | { |
222 | struct kprobe *kp; | |
650b7b23 | 223 | unsigned long faddr; |
86b4ce31 | 224 | |
b46b3d70 | 225 | kp = get_kprobe((void *)addr); |
650b7b23 | 226 | faddr = ftrace_location(addr); |
2a6730c8 PM |
227 | /* |
228 | * Addresses inside the ftrace location are refused by | |
229 | * arch_check_ftrace_location(). Something went terribly wrong | |
230 | * if such an address is checked here. | |
231 | */ | |
232 | if (WARN_ON(faddr && faddr != addr)) | |
233 | return 0UL; | |
650b7b23 PM |
234 | /* |
235 | * Use the current code if it is not modified by Kprobe | |
236 | * and it cannot be modified by ftrace. | |
237 | */ | |
238 | if (!kp && !faddr) | |
86b4ce31 | 239 | return addr; |
b46b3d70 MH |
240 | |
241 | /* | |
650b7b23 PM |
242 | * Basically, kp->ainsn.insn has an original instruction. |
243 | * However, RIP-relative instruction can not do single-stepping | |
244 | * at different place, __copy_instruction() tweaks the displacement of | |
245 | * that instruction. In that case, we can't recover the instruction | |
246 | * from the kp->ainsn.insn. | |
247 | * | |
248 | * On the other hand, in case on normal Kprobe, kp->opcode has a copy | |
249 | * of the first byte of the probed instruction, which is overwritten | |
250 | * by int3. And the instruction at kp->addr is not modified by kprobes | |
251 | * except for the first byte, we can recover the original instruction | |
252 | * from it and kp->opcode. | |
b46b3d70 | 253 | * |
650b7b23 PM |
254 | * In case of Kprobes using ftrace, we do not have a copy of |
255 | * the original instruction. In fact, the ftrace location might | |
256 | * be modified at anytime and even could be in an inconsistent state. | |
257 | * Fortunately, we know that the original code is the ideal 5-byte | |
258 | * long NOP. | |
b46b3d70 | 259 | */ |
ea1e34fc MH |
260 | if (probe_kernel_read(buf, (void *)addr, |
261 | MAX_INSN_SIZE * sizeof(kprobe_opcode_t))) | |
262 | return 0UL; | |
263 | ||
650b7b23 PM |
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. | |
ea1e34fc | 275 | * Returns zero if the instruction can not get recovered (or access failed). |
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 | /* | |
129d17e8 MH |
347 | * Copy an instruction with recovering modified instruction by kprobes |
348 | * and adjust the displacement if the instruction uses the %rip-relative | |
349 | * addressing mode. | |
350 | * This returns the length of copied instruction, or 0 if it has an error. | |
1da177e4 | 351 | */ |
a8d11cd0 | 352 | int __copy_instruction(u8 *dest, u8 *src, struct insn *insn) |
1da177e4 | 353 | { |
c0f7ac3a | 354 | kprobe_opcode_t buf[MAX_INSN_SIZE]; |
6ba48ff4 DH |
355 | unsigned long recovered_insn = |
356 | recover_probed_instruction(buf, (unsigned long)src); | |
86b4ce31 | 357 | |
a8d11cd0 | 358 | if (!recovered_insn || !insn) |
2a6730c8 | 359 | return 0; |
c80e5c0c | 360 | |
a8d11cd0 MH |
361 | /* This can access kernel text if given address is not recovered */ |
362 | if (probe_kernel_read(dest, (void *)recovered_insn, MAX_INSN_SIZE)) | |
86b4ce31 | 363 | return 0; |
ea1e34fc | 364 | |
a8d11cd0 MH |
365 | kernel_insn_init(insn, dest, MAX_INSN_SIZE); |
366 | insn_get_length(insn); | |
367 | ||
368 | /* Another subsystem puts a breakpoint, failed to recover */ | |
369 | if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION) | |
ea1e34fc | 370 | return 0; |
c0f7ac3a MH |
371 | |
372 | #ifdef CONFIG_X86_64 | |
129d17e8 | 373 | /* Only x86_64 has RIP relative instructions */ |
a8d11cd0 | 374 | if (insn_rip_relative(insn)) { |
89ae465b MH |
375 | s64 newdisp; |
376 | u8 *disp; | |
89ae465b MH |
377 | /* |
378 | * The copied instruction uses the %rip-relative addressing | |
379 | * mode. Adjust the displacement for the difference between | |
380 | * the original location of this instruction and the location | |
381 | * of the copy that will actually be run. The tricky bit here | |
382 | * is making sure that the sign extension happens correctly in | |
383 | * this calculation, since we need a signed 32-bit result to | |
384 | * be sign-extended to 64 bits when it's added to the %rip | |
385 | * value and yield the same 64-bit result that the sign- | |
386 | * extension of the original signed 32-bit displacement would | |
387 | * have given. | |
388 | */ | |
a8d11cd0 MH |
389 | newdisp = (u8 *) src + (s64) insn->displacement.value |
390 | - (u8 *) dest; | |
8101376d MH |
391 | if ((s64) (s32) newdisp != newdisp) { |
392 | pr_err("Kprobes error: new displacement does not fit into s32 (%llx)\n", newdisp); | |
a8d11cd0 MH |
393 | pr_err("\tSrc: %p, Dest: %p, old disp: %x\n", |
394 | src, dest, insn->displacement.value); | |
8101376d MH |
395 | return 0; |
396 | } | |
a8d11cd0 | 397 | disp = (u8 *) dest + insn_offset_displacement(insn); |
89ae465b | 398 | *(s32 *) disp = (s32) newdisp; |
1da177e4 | 399 | } |
d6be29b8 | 400 | #endif |
a8d11cd0 | 401 | return insn->length; |
31f80e45 | 402 | } |
1da177e4 | 403 | |
804dec5b | 404 | /* Prepare reljump right after instruction to boost */ |
a8d11cd0 | 405 | static void prepare_boost(struct kprobe *p, struct insn *insn) |
804dec5b | 406 | { |
a8d11cd0 MH |
407 | if (can_boost(insn, p->addr) && |
408 | MAX_INSN_SIZE - insn->length >= RELATIVEJUMP_SIZE) { | |
804dec5b MH |
409 | /* |
410 | * These instructions can be executed directly if it | |
411 | * jumps back to correct address. | |
412 | */ | |
a8d11cd0 MH |
413 | synthesize_reljump(p->ainsn.insn + insn->length, |
414 | p->addr + insn->length); | |
490154bc | 415 | p->ainsn.boostable = true; |
804dec5b | 416 | } else { |
490154bc | 417 | p->ainsn.boostable = false; |
804dec5b MH |
418 | } |
419 | } | |
420 | ||
c93f5cf5 MH |
421 | /* Recover page to RW mode before releasing it */ |
422 | void free_insn_page(void *page) | |
423 | { | |
424 | set_memory_nx((unsigned long)page & PAGE_MASK, 1); | |
425 | set_memory_rw((unsigned long)page & PAGE_MASK, 1); | |
426 | module_memfree(page); | |
427 | } | |
428 | ||
7ec8a97a | 429 | static int arch_copy_kprobe(struct kprobe *p) |
1da177e4 | 430 | { |
a8d11cd0 | 431 | struct insn insn; |
804dec5b | 432 | int len; |
003002e0 | 433 | |
d0381c81 MH |
434 | set_memory_rw((unsigned long)p->ainsn.insn & PAGE_MASK, 1); |
435 | ||
46484688 | 436 | /* Copy an instruction with recovering if other optprobe modifies it.*/ |
a8d11cd0 | 437 | len = __copy_instruction(p->ainsn.insn, p->addr, &insn); |
804dec5b | 438 | if (!len) |
003002e0 | 439 | return -EINVAL; |
46484688 | 440 | |
c0f7ac3a | 441 | /* |
46484688 MH |
442 | * __copy_instruction can modify the displacement of the instruction, |
443 | * but it doesn't affect boostable check. | |
c0f7ac3a | 444 | */ |
a8d11cd0 | 445 | prepare_boost(p, &insn); |
8533bbe9 | 446 | |
d0381c81 MH |
447 | set_memory_ro((unsigned long)p->ainsn.insn & PAGE_MASK, 1); |
448 | ||
9a556ab9 MH |
449 | /* Check whether the instruction modifies Interrupt Flag or not */ |
450 | p->ainsn.if_modifier = is_IF_modifier(p->ainsn.insn); | |
451 | ||
46484688 MH |
452 | /* Also, displacement change doesn't affect the first byte */ |
453 | p->opcode = p->ainsn.insn[0]; | |
003002e0 MH |
454 | |
455 | return 0; | |
1da177e4 LT |
456 | } |
457 | ||
7ec8a97a | 458 | int arch_prepare_kprobe(struct kprobe *p) |
8533bbe9 | 459 | { |
4554dbcb MH |
460 | if (alternatives_text_reserved(p->addr, p->addr)) |
461 | return -EINVAL; | |
462 | ||
b46b3d70 MH |
463 | if (!can_probe((unsigned long)p->addr)) |
464 | return -EILSEQ; | |
8533bbe9 MH |
465 | /* insn: must be on special executable page on x86. */ |
466 | p->ainsn.insn = get_insn_slot(); | |
467 | if (!p->ainsn.insn) | |
468 | return -ENOMEM; | |
003002e0 MH |
469 | |
470 | return arch_copy_kprobe(p); | |
8533bbe9 MH |
471 | } |
472 | ||
7ec8a97a | 473 | void arch_arm_kprobe(struct kprobe *p) |
1da177e4 | 474 | { |
19d36ccd | 475 | text_poke(p->addr, ((unsigned char []){BREAKPOINT_INSTRUCTION}), 1); |
1da177e4 LT |
476 | } |
477 | ||
7ec8a97a | 478 | void arch_disarm_kprobe(struct kprobe *p) |
1da177e4 | 479 | { |
19d36ccd | 480 | text_poke(p->addr, &p->opcode, 1); |
7e1048b1 RL |
481 | } |
482 | ||
7ec8a97a | 483 | void arch_remove_kprobe(struct kprobe *p) |
7e1048b1 | 484 | { |
12941560 | 485 | if (p->ainsn.insn) { |
490154bc | 486 | free_insn_slot(p->ainsn.insn, p->ainsn.boostable); |
12941560 MH |
487 | p->ainsn.insn = NULL; |
488 | } | |
1da177e4 LT |
489 | } |
490 | ||
9326638c MH |
491 | static nokprobe_inline void |
492 | save_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 493 | { |
e7a510f9 AM |
494 | kcb->prev_kprobe.kp = kprobe_running(); |
495 | kcb->prev_kprobe.status = kcb->kprobe_status; | |
8533bbe9 MH |
496 | kcb->prev_kprobe.old_flags = kcb->kprobe_old_flags; |
497 | kcb->prev_kprobe.saved_flags = kcb->kprobe_saved_flags; | |
aa3d7e3d PP |
498 | } |
499 | ||
9326638c MH |
500 | static nokprobe_inline void |
501 | restore_previous_kprobe(struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 502 | { |
b76834bc | 503 | __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp); |
e7a510f9 | 504 | kcb->kprobe_status = kcb->prev_kprobe.status; |
8533bbe9 MH |
505 | kcb->kprobe_old_flags = kcb->prev_kprobe.old_flags; |
506 | kcb->kprobe_saved_flags = kcb->prev_kprobe.saved_flags; | |
aa3d7e3d PP |
507 | } |
508 | ||
9326638c MH |
509 | static nokprobe_inline void |
510 | set_current_kprobe(struct kprobe *p, struct pt_regs *regs, | |
511 | struct kprobe_ctlblk *kcb) | |
aa3d7e3d | 512 | { |
b76834bc | 513 | __this_cpu_write(current_kprobe, p); |
8533bbe9 | 514 | kcb->kprobe_saved_flags = kcb->kprobe_old_flags |
053de044 | 515 | = (regs->flags & (X86_EFLAGS_TF | X86_EFLAGS_IF)); |
9a556ab9 | 516 | if (p->ainsn.if_modifier) |
053de044 | 517 | kcb->kprobe_saved_flags &= ~X86_EFLAGS_IF; |
aa3d7e3d PP |
518 | } |
519 | ||
9326638c | 520 | static nokprobe_inline void clear_btf(void) |
1ecc798c | 521 | { |
ea8e61b7 PZ |
522 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
523 | unsigned long debugctl = get_debugctlmsr(); | |
524 | ||
525 | debugctl &= ~DEBUGCTLMSR_BTF; | |
526 | update_debugctlmsr(debugctl); | |
527 | } | |
1ecc798c RM |
528 | } |
529 | ||
9326638c | 530 | static nokprobe_inline void restore_btf(void) |
1ecc798c | 531 | { |
ea8e61b7 PZ |
532 | if (test_thread_flag(TIF_BLOCKSTEP)) { |
533 | unsigned long debugctl = get_debugctlmsr(); | |
534 | ||
535 | debugctl |= DEBUGCTLMSR_BTF; | |
536 | update_debugctlmsr(debugctl); | |
537 | } | |
1ecc798c RM |
538 | } |
539 | ||
9326638c | 540 | void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) |
73649dab | 541 | { |
8533bbe9 | 542 | unsigned long *sara = stack_addr(regs); |
ba8af12f | 543 | |
4c4308cb | 544 | ri->ret_addr = (kprobe_opcode_t *) *sara; |
8533bbe9 | 545 | |
4c4308cb CH |
546 | /* Replace the return addr with trampoline addr */ |
547 | *sara = (unsigned long) &kretprobe_trampoline; | |
73649dab | 548 | } |
9326638c | 549 | NOKPROBE_SYMBOL(arch_prepare_kretprobe); |
f315decb | 550 | |
9326638c MH |
551 | static void setup_singlestep(struct kprobe *p, struct pt_regs *regs, |
552 | struct kprobe_ctlblk *kcb, int reenter) | |
f315decb | 553 | { |
c0f7ac3a MH |
554 | if (setup_detour_execution(p, regs, reenter)) |
555 | return; | |
556 | ||
615d0ebb | 557 | #if !defined(CONFIG_PREEMPT) |
490154bc | 558 | if (p->ainsn.boostable && !p->post_handler) { |
f315decb | 559 | /* Boost up -- we can execute copied instructions directly */ |
0f94eb63 MH |
560 | if (!reenter) |
561 | reset_current_kprobe(); | |
562 | /* | |
563 | * Reentering boosted probe doesn't reset current_kprobe, | |
564 | * nor set current_kprobe, because it doesn't use single | |
565 | * stepping. | |
566 | */ | |
f315decb AS |
567 | regs->ip = (unsigned long)p->ainsn.insn; |
568 | preempt_enable_no_resched(); | |
569 | return; | |
570 | } | |
571 | #endif | |
0f94eb63 MH |
572 | if (reenter) { |
573 | save_previous_kprobe(kcb); | |
574 | set_current_kprobe(p, regs, kcb); | |
575 | kcb->kprobe_status = KPROBE_REENTER; | |
576 | } else | |
577 | kcb->kprobe_status = KPROBE_HIT_SS; | |
578 | /* Prepare real single stepping */ | |
579 | clear_btf(); | |
580 | regs->flags |= X86_EFLAGS_TF; | |
581 | regs->flags &= ~X86_EFLAGS_IF; | |
582 | /* single step inline if the instruction is an int3 */ | |
583 | if (p->opcode == BREAKPOINT_INSTRUCTION) | |
584 | regs->ip = (unsigned long)p->addr; | |
585 | else | |
586 | regs->ip = (unsigned long)p->ainsn.insn; | |
f315decb | 587 | } |
9326638c | 588 | NOKPROBE_SYMBOL(setup_singlestep); |
f315decb | 589 | |
40102d4a HH |
590 | /* |
591 | * We have reentered the kprobe_handler(), since another probe was hit while | |
592 | * within the handler. We save the original kprobes variables and just single | |
593 | * step on the instruction of the new probe without calling any user handlers. | |
594 | */ | |
9326638c MH |
595 | static int reenter_kprobe(struct kprobe *p, struct pt_regs *regs, |
596 | struct kprobe_ctlblk *kcb) | |
40102d4a | 597 | { |
f315decb AS |
598 | switch (kcb->kprobe_status) { |
599 | case KPROBE_HIT_SSDONE: | |
f315decb | 600 | case KPROBE_HIT_ACTIVE: |
6a5022a5 | 601 | case KPROBE_HIT_SS: |
fb8830e7 | 602 | kprobes_inc_nmissed_count(p); |
0f94eb63 | 603 | setup_singlestep(p, regs, kcb, 1); |
f315decb | 604 | break; |
6a5022a5 | 605 | case KPROBE_REENTER: |
e9afe9e1 MH |
606 | /* A probe has been hit in the codepath leading up to, or just |
607 | * after, single-stepping of a probed instruction. This entire | |
608 | * codepath should strictly reside in .kprobes.text section. | |
609 | * Raise a BUG or we'll continue in an endless reentering loop | |
610 | * and eventually a stack overflow. | |
611 | */ | |
612 | printk(KERN_WARNING "Unrecoverable kprobe detected at %p.\n", | |
613 | p->addr); | |
614 | dump_kprobe(p); | |
615 | BUG(); | |
f315decb AS |
616 | default: |
617 | /* impossible cases */ | |
618 | WARN_ON(1); | |
fb8830e7 | 619 | return 0; |
59e87cdc | 620 | } |
f315decb | 621 | |
59e87cdc | 622 | return 1; |
40102d4a | 623 | } |
9326638c | 624 | NOKPROBE_SYMBOL(reenter_kprobe); |
73649dab | 625 | |
8533bbe9 MH |
626 | /* |
627 | * Interrupts are disabled on entry as trap3 is an interrupt gate and they | |
af901ca1 | 628 | * remain disabled throughout this function. |
8533bbe9 | 629 | */ |
9326638c | 630 | int kprobe_int3_handler(struct pt_regs *regs) |
1da177e4 | 631 | { |
8533bbe9 | 632 | kprobe_opcode_t *addr; |
f315decb | 633 | struct kprobe *p; |
d217d545 AM |
634 | struct kprobe_ctlblk *kcb; |
635 | ||
f39b6f0e | 636 | if (user_mode(regs)) |
0cdd192c AL |
637 | return 0; |
638 | ||
8533bbe9 | 639 | addr = (kprobe_opcode_t *)(regs->ip - sizeof(kprobe_opcode_t)); |
d217d545 AM |
640 | /* |
641 | * We don't want to be preempted for the entire | |
f315decb AS |
642 | * duration of kprobe processing. We conditionally |
643 | * re-enable preemption at the end of this function, | |
644 | * and also in reenter_kprobe() and setup_singlestep(). | |
d217d545 AM |
645 | */ |
646 | preempt_disable(); | |
1da177e4 | 647 | |
f315decb | 648 | kcb = get_kprobe_ctlblk(); |
b9760156 | 649 | p = get_kprobe(addr); |
f315decb | 650 | |
b9760156 | 651 | if (p) { |
b9760156 | 652 | if (kprobe_running()) { |
f315decb AS |
653 | if (reenter_kprobe(p, regs, kcb)) |
654 | return 1; | |
1da177e4 | 655 | } else { |
b9760156 HH |
656 | set_current_kprobe(p, regs, kcb); |
657 | kcb->kprobe_status = KPROBE_HIT_ACTIVE; | |
f315decb | 658 | |
1da177e4 | 659 | /* |
f315decb AS |
660 | * If we have no pre-handler or it returned 0, we |
661 | * continue with normal processing. If we have a | |
662 | * pre-handler and it returned non-zero, it prepped | |
663 | * for calling the break_handler below on re-entry | |
664 | * for jprobe processing, so get out doing nothing | |
665 | * more here. | |
1da177e4 | 666 | */ |
f315decb | 667 | if (!p->pre_handler || !p->pre_handler(p, regs)) |
0f94eb63 | 668 | setup_singlestep(p, regs, kcb, 0); |
f315decb | 669 | return 1; |
b9760156 | 670 | } |
829e9245 MH |
671 | } else if (*addr != BREAKPOINT_INSTRUCTION) { |
672 | /* | |
673 | * The breakpoint instruction was removed right | |
674 | * after we hit it. Another cpu has removed | |
675 | * either a probepoint or a debugger breakpoint | |
676 | * at this address. In either case, no further | |
677 | * handling of this interrupt is appropriate. | |
678 | * Back up over the (now missing) int3 and run | |
679 | * the original instruction. | |
680 | */ | |
681 | regs->ip = (unsigned long)addr; | |
682 | preempt_enable_no_resched(); | |
683 | return 1; | |
f315decb | 684 | } else if (kprobe_running()) { |
b76834bc | 685 | p = __this_cpu_read(current_kprobe); |
f315decb | 686 | if (p->break_handler && p->break_handler(p, regs)) { |
e7dbfe34 MH |
687 | if (!skip_singlestep(p, regs, kcb)) |
688 | setup_singlestep(p, regs, kcb, 0); | |
f315decb | 689 | return 1; |
1da177e4 | 690 | } |
f315decb | 691 | } /* else: not a kprobe fault; let the kernel handle it */ |
1da177e4 | 692 | |
d217d545 | 693 | preempt_enable_no_resched(); |
f315decb | 694 | return 0; |
1da177e4 | 695 | } |
9326638c | 696 | NOKPROBE_SYMBOL(kprobe_int3_handler); |
1da177e4 | 697 | |
73649dab | 698 | /* |
da07ab03 MH |
699 | * When a retprobed function returns, this code saves registers and |
700 | * calls trampoline_handler() runs, which calls the kretprobe's handler. | |
73649dab | 701 | */ |
c1c355ce JP |
702 | asm( |
703 | ".global kretprobe_trampoline\n" | |
704 | ".type kretprobe_trampoline, @function\n" | |
705 | "kretprobe_trampoline:\n" | |
d6be29b8 | 706 | #ifdef CONFIG_X86_64 |
c1c355ce JP |
707 | /* We don't bother saving the ss register */ |
708 | " pushq %rsp\n" | |
709 | " pushfq\n" | |
710 | SAVE_REGS_STRING | |
711 | " movq %rsp, %rdi\n" | |
712 | " call trampoline_handler\n" | |
713 | /* Replace saved sp with true return address. */ | |
714 | " movq %rax, 152(%rsp)\n" | |
715 | RESTORE_REGS_STRING | |
716 | " popfq\n" | |
d6be29b8 | 717 | #else |
c1c355ce JP |
718 | " pushf\n" |
719 | SAVE_REGS_STRING | |
720 | " movl %esp, %eax\n" | |
721 | " call trampoline_handler\n" | |
722 | /* Move flags to cs */ | |
723 | " movl 56(%esp), %edx\n" | |
724 | " movl %edx, 52(%esp)\n" | |
725 | /* Replace saved flags with true return address. */ | |
726 | " movl %eax, 56(%esp)\n" | |
727 | RESTORE_REGS_STRING | |
728 | " popf\n" | |
d6be29b8 | 729 | #endif |
c1c355ce JP |
730 | " ret\n" |
731 | ".size kretprobe_trampoline, .-kretprobe_trampoline\n" | |
732 | ); | |
9326638c | 733 | NOKPROBE_SYMBOL(kretprobe_trampoline); |
87aaff2a | 734 | STACK_FRAME_NON_STANDARD(kretprobe_trampoline); |
73649dab RL |
735 | |
736 | /* | |
da07ab03 | 737 | * Called from kretprobe_trampoline |
73649dab | 738 | */ |
9326638c | 739 | __visible __used void *trampoline_handler(struct pt_regs *regs) |
73649dab | 740 | { |
62c27be0 | 741 | struct kretprobe_instance *ri = NULL; |
99219a3f | 742 | struct hlist_head *head, empty_rp; |
b67bfe0d | 743 | struct hlist_node *tmp; |
991a51d8 | 744 | unsigned long flags, orig_ret_address = 0; |
d6be29b8 | 745 | unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; |
737480a0 | 746 | kprobe_opcode_t *correct_ret_addr = NULL; |
73649dab | 747 | |
99219a3f | 748 | INIT_HLIST_HEAD(&empty_rp); |
ef53d9c5 | 749 | kretprobe_hash_lock(current, &head, &flags); |
8533bbe9 | 750 | /* fixup registers */ |
d6be29b8 | 751 | #ifdef CONFIG_X86_64 |
da07ab03 | 752 | regs->cs = __KERNEL_CS; |
d6be29b8 MH |
753 | #else |
754 | regs->cs = __KERNEL_CS | get_kernel_rpl(); | |
fee039a1 | 755 | regs->gs = 0; |
d6be29b8 | 756 | #endif |
da07ab03 | 757 | regs->ip = trampoline_address; |
8533bbe9 | 758 | regs->orig_ax = ~0UL; |
73649dab | 759 | |
ba8af12f RL |
760 | /* |
761 | * It is possible to have multiple instances associated with a given | |
8533bbe9 | 762 | * task either because multiple functions in the call path have |
025dfdaf | 763 | * return probes installed on them, and/or more than one |
ba8af12f RL |
764 | * return probe was registered for a target function. |
765 | * | |
766 | * We can handle this because: | |
8533bbe9 | 767 | * - instances are always pushed into the head of the list |
ba8af12f | 768 | * - when multiple return probes are registered for the same |
8533bbe9 MH |
769 | * function, the (chronologically) first instance's ret_addr |
770 | * will be the real return address, and all the rest will | |
771 | * point to kretprobe_trampoline. | |
ba8af12f | 772 | */ |
b6263178 | 773 | hlist_for_each_entry(ri, head, hlist) { |
62c27be0 | 774 | if (ri->task != current) |
ba8af12f | 775 | /* another task is sharing our hash bucket */ |
62c27be0 | 776 | continue; |
ba8af12f | 777 | |
737480a0 KS |
778 | orig_ret_address = (unsigned long)ri->ret_addr; |
779 | ||
780 | if (orig_ret_address != trampoline_address) | |
781 | /* | |
782 | * This is the real return address. Any other | |
783 | * instances associated with this task are for | |
784 | * other calls deeper on the call stack | |
785 | */ | |
786 | break; | |
787 | } | |
788 | ||
789 | kretprobe_assert(ri, orig_ret_address, trampoline_address); | |
790 | ||
791 | correct_ret_addr = ri->ret_addr; | |
b67bfe0d | 792 | hlist_for_each_entry_safe(ri, tmp, head, hlist) { |
737480a0 KS |
793 | if (ri->task != current) |
794 | /* another task is sharing our hash bucket */ | |
795 | continue; | |
796 | ||
797 | orig_ret_address = (unsigned long)ri->ret_addr; | |
da07ab03 | 798 | if (ri->rp && ri->rp->handler) { |
b76834bc | 799 | __this_cpu_write(current_kprobe, &ri->rp->kp); |
da07ab03 | 800 | get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
737480a0 | 801 | ri->ret_addr = correct_ret_addr; |
ba8af12f | 802 | ri->rp->handler(ri, regs); |
b76834bc | 803 | __this_cpu_write(current_kprobe, NULL); |
da07ab03 | 804 | } |
ba8af12f | 805 | |
99219a3f | 806 | recycle_rp_inst(ri, &empty_rp); |
ba8af12f RL |
807 | |
808 | if (orig_ret_address != trampoline_address) | |
809 | /* | |
810 | * This is the real return address. Any other | |
811 | * instances associated with this task are for | |
812 | * other calls deeper on the call stack | |
813 | */ | |
814 | break; | |
73649dab | 815 | } |
ba8af12f | 816 | |
ef53d9c5 | 817 | kretprobe_hash_unlock(current, &flags); |
ba8af12f | 818 | |
b67bfe0d | 819 | hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { |
99219a3f | 820 | hlist_del(&ri->hlist); |
821 | kfree(ri); | |
822 | } | |
da07ab03 | 823 | return (void *)orig_ret_address; |
73649dab | 824 | } |
9326638c | 825 | NOKPROBE_SYMBOL(trampoline_handler); |
73649dab | 826 | |
1da177e4 LT |
827 | /* |
828 | * Called after single-stepping. p->addr is the address of the | |
829 | * instruction whose first byte has been replaced by the "int 3" | |
830 | * instruction. To avoid the SMP problems that can occur when we | |
831 | * temporarily put back the original opcode to single-step, we | |
832 | * single-stepped a copy of the instruction. The address of this | |
833 | * copy is p->ainsn.insn. | |
834 | * | |
835 | * This function prepares to return from the post-single-step | |
836 | * interrupt. We have to fix up the stack as follows: | |
837 | * | |
838 | * 0) Except in the case of absolute or indirect jump or call instructions, | |
65ea5b03 | 839 | * the new ip is relative to the copied instruction. We need to make |
1da177e4 LT |
840 | * it relative to the original instruction. |
841 | * | |
842 | * 1) If the single-stepped instruction was pushfl, then the TF and IF | |
65ea5b03 | 843 | * flags are set in the just-pushed flags, and may need to be cleared. |
1da177e4 LT |
844 | * |
845 | * 2) If the single-stepped instruction was a call, the return address | |
846 | * that is atop the stack is the address following the copied instruction. | |
847 | * We need to make it the address following the original instruction. | |
aa470140 MH |
848 | * |
849 | * If this is the first time we've single-stepped the instruction at | |
850 | * this probepoint, and the instruction is boostable, boost it: add a | |
851 | * jump instruction after the copied instruction, that jumps to the next | |
852 | * instruction after the probepoint. | |
1da177e4 | 853 | */ |
9326638c MH |
854 | static void resume_execution(struct kprobe *p, struct pt_regs *regs, |
855 | struct kprobe_ctlblk *kcb) | |
1da177e4 | 856 | { |
8533bbe9 MH |
857 | unsigned long *tos = stack_addr(regs); |
858 | unsigned long copy_ip = (unsigned long)p->ainsn.insn; | |
859 | unsigned long orig_ip = (unsigned long)p->addr; | |
1da177e4 LT |
860 | kprobe_opcode_t *insn = p->ainsn.insn; |
861 | ||
567a9fd8 MH |
862 | /* Skip prefixes */ |
863 | insn = skip_prefixes(insn); | |
1da177e4 | 864 | |
053de044 | 865 | regs->flags &= ~X86_EFLAGS_TF; |
1da177e4 | 866 | switch (*insn) { |
0b0122fa | 867 | case 0x9c: /* pushfl */ |
053de044 | 868 | *tos &= ~(X86_EFLAGS_TF | X86_EFLAGS_IF); |
8533bbe9 | 869 | *tos |= kcb->kprobe_old_flags; |
1da177e4 | 870 | break; |
0b0122fa MH |
871 | case 0xc2: /* iret/ret/lret */ |
872 | case 0xc3: | |
0b9e2cac | 873 | case 0xca: |
0b0122fa MH |
874 | case 0xcb: |
875 | case 0xcf: | |
876 | case 0xea: /* jmp absolute -- ip is correct */ | |
877 | /* ip is already adjusted, no more changes required */ | |
490154bc | 878 | p->ainsn.boostable = true; |
0b0122fa MH |
879 | goto no_change; |
880 | case 0xe8: /* call relative - Fix return addr */ | |
8533bbe9 | 881 | *tos = orig_ip + (*tos - copy_ip); |
1da177e4 | 882 | break; |
e7b5e11e | 883 | #ifdef CONFIG_X86_32 |
d6be29b8 MH |
884 | case 0x9a: /* call absolute -- same as call absolute, indirect */ |
885 | *tos = orig_ip + (*tos - copy_ip); | |
886 | goto no_change; | |
887 | #endif | |
1da177e4 | 888 | case 0xff: |
dc49e344 | 889 | if ((insn[1] & 0x30) == 0x10) { |
8533bbe9 MH |
890 | /* |
891 | * call absolute, indirect | |
892 | * Fix return addr; ip is correct. | |
893 | * But this is not boostable | |
894 | */ | |
895 | *tos = orig_ip + (*tos - copy_ip); | |
0b0122fa | 896 | goto no_change; |
8533bbe9 MH |
897 | } else if (((insn[1] & 0x31) == 0x20) || |
898 | ((insn[1] & 0x31) == 0x21)) { | |
899 | /* | |
900 | * jmp near and far, absolute indirect | |
901 | * ip is correct. And this is boostable | |
902 | */ | |
490154bc | 903 | p->ainsn.boostable = true; |
0b0122fa | 904 | goto no_change; |
1da177e4 | 905 | } |
1da177e4 LT |
906 | default: |
907 | break; | |
908 | } | |
909 | ||
8533bbe9 | 910 | regs->ip += orig_ip - copy_ip; |
65ea5b03 | 911 | |
0b0122fa | 912 | no_change: |
1ecc798c | 913 | restore_btf(); |
1da177e4 | 914 | } |
9326638c | 915 | NOKPROBE_SYMBOL(resume_execution); |
1da177e4 | 916 | |
8533bbe9 MH |
917 | /* |
918 | * Interrupts are disabled on entry as trap1 is an interrupt gate and they | |
af901ca1 | 919 | * remain disabled throughout this function. |
8533bbe9 | 920 | */ |
9326638c | 921 | int kprobe_debug_handler(struct pt_regs *regs) |
1da177e4 | 922 | { |
e7a510f9 AM |
923 | struct kprobe *cur = kprobe_running(); |
924 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
925 | ||
926 | if (!cur) | |
1da177e4 LT |
927 | return 0; |
928 | ||
acb5b8a2 YL |
929 | resume_execution(cur, regs, kcb); |
930 | regs->flags |= kcb->kprobe_saved_flags; | |
acb5b8a2 | 931 | |
e7a510f9 AM |
932 | if ((kcb->kprobe_status != KPROBE_REENTER) && cur->post_handler) { |
933 | kcb->kprobe_status = KPROBE_HIT_SSDONE; | |
934 | cur->post_handler(cur, regs, 0); | |
aa3d7e3d | 935 | } |
1da177e4 | 936 | |
8533bbe9 | 937 | /* Restore back the original saved kprobes variables and continue. */ |
e7a510f9 AM |
938 | if (kcb->kprobe_status == KPROBE_REENTER) { |
939 | restore_previous_kprobe(kcb); | |
aa3d7e3d | 940 | goto out; |
aa3d7e3d | 941 | } |
e7a510f9 | 942 | reset_current_kprobe(); |
aa3d7e3d | 943 | out: |
1da177e4 LT |
944 | preempt_enable_no_resched(); |
945 | ||
946 | /* | |
65ea5b03 | 947 | * if somebody else is singlestepping across a probe point, flags |
1da177e4 LT |
948 | * will have TF set, in which case, continue the remaining processing |
949 | * of do_debug, as if this is not a probe hit. | |
950 | */ | |
053de044 | 951 | if (regs->flags & X86_EFLAGS_TF) |
1da177e4 LT |
952 | return 0; |
953 | ||
954 | return 1; | |
955 | } | |
9326638c | 956 | NOKPROBE_SYMBOL(kprobe_debug_handler); |
1da177e4 | 957 | |
9326638c | 958 | int kprobe_fault_handler(struct pt_regs *regs, int trapnr) |
1da177e4 | 959 | { |
e7a510f9 AM |
960 | struct kprobe *cur = kprobe_running(); |
961 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); | |
962 | ||
6381c24c MH |
963 | if (unlikely(regs->ip == (unsigned long)cur->ainsn.insn)) { |
964 | /* This must happen on single-stepping */ | |
965 | WARN_ON(kcb->kprobe_status != KPROBE_HIT_SS && | |
966 | kcb->kprobe_status != KPROBE_REENTER); | |
c28f8966 PP |
967 | /* |
968 | * We are here because the instruction being single | |
969 | * stepped caused a page fault. We reset the current | |
65ea5b03 | 970 | * kprobe and the ip points back to the probe address |
c28f8966 PP |
971 | * and allow the page fault handler to continue as a |
972 | * normal page fault. | |
973 | */ | |
65ea5b03 | 974 | regs->ip = (unsigned long)cur->addr; |
dcfc4724 MH |
975 | /* |
976 | * Trap flag (TF) has been set here because this fault | |
977 | * happened where the single stepping will be done. | |
978 | * So clear it by resetting the current kprobe: | |
979 | */ | |
980 | regs->flags &= ~X86_EFLAGS_TF; | |
981 | ||
982 | /* | |
983 | * If the TF flag was set before the kprobe hit, | |
984 | * don't touch it: | |
985 | */ | |
8533bbe9 | 986 | regs->flags |= kcb->kprobe_old_flags; |
dcfc4724 | 987 | |
c28f8966 PP |
988 | if (kcb->kprobe_status == KPROBE_REENTER) |
989 | restore_previous_kprobe(kcb); | |
990 | else | |
991 | reset_current_kprobe(); | |
1da177e4 | 992 | preempt_enable_no_resched(); |
6381c24c MH |
993 | } else if (kcb->kprobe_status == KPROBE_HIT_ACTIVE || |
994 | kcb->kprobe_status == KPROBE_HIT_SSDONE) { | |
c28f8966 PP |
995 | /* |
996 | * We increment the nmissed count for accounting, | |
8533bbe9 | 997 | * we can also use npre/npostfault count for accounting |
c28f8966 PP |
998 | * these specific fault cases. |
999 | */ | |
1000 | kprobes_inc_nmissed_count(cur); | |
1001 | ||
1002 | /* | |
1003 | * We come here because instructions in the pre/post | |
1004 | * handler caused the page_fault, this could happen | |
1005 | * if handler tries to access user space by | |
1006 | * copy_from_user(), get_user() etc. Let the | |
1007 | * user-specified handler try to fix it first. | |
1008 | */ | |
1009 | if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) | |
1010 | return 1; | |
1011 | ||
1012 | /* | |
1013 | * In case the user-specified fault handler returned | |
1014 | * zero, try to fix up. | |
1015 | */ | |
548acf19 | 1016 | if (fixup_exception(regs, trapnr)) |
d6be29b8 | 1017 | return 1; |
6d48583b | 1018 | |
c28f8966 | 1019 | /* |
8533bbe9 | 1020 | * fixup routine could not handle it, |
c28f8966 PP |
1021 | * Let do_page_fault() fix it. |
1022 | */ | |
1da177e4 | 1023 | } |
6381c24c | 1024 | |
1da177e4 LT |
1025 | return 0; |
1026 | } | |
9326638c | 1027 | NOKPROBE_SYMBOL(kprobe_fault_handler); |
1da177e4 LT |
1028 | |
1029 | /* | |
1030 | * Wrapper routine for handling exceptions. | |
1031 | */ | |
9326638c MH |
1032 | int kprobe_exceptions_notify(struct notifier_block *self, unsigned long val, |
1033 | void *data) | |
1da177e4 | 1034 | { |
ade1af77 | 1035 | struct die_args *args = data; |
66ff2d06 AM |
1036 | int ret = NOTIFY_DONE; |
1037 | ||
f39b6f0e | 1038 | if (args->regs && user_mode(args->regs)) |
2326c770 | 1039 | return ret; |
1040 | ||
6f6343f5 | 1041 | if (val == DIE_GPF) { |
b506a9d0 QB |
1042 | /* |
1043 | * To be potentially processing a kprobe fault and to | |
1044 | * trust the result from kprobe_running(), we have | |
1045 | * be non-preemptible. | |
1046 | */ | |
1047 | if (!preemptible() && kprobe_running() && | |
1da177e4 | 1048 | kprobe_fault_handler(args->regs, args->trapnr)) |
66ff2d06 | 1049 | ret = NOTIFY_STOP; |
1da177e4 | 1050 | } |
66ff2d06 | 1051 | return ret; |
1da177e4 | 1052 | } |
9326638c | 1053 | NOKPROBE_SYMBOL(kprobe_exceptions_notify); |
1da177e4 | 1054 | |
9326638c | 1055 | int setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 LT |
1056 | { |
1057 | struct jprobe *jp = container_of(p, struct jprobe, kp); | |
1058 | unsigned long addr; | |
e7a510f9 | 1059 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1da177e4 | 1060 | |
e7a510f9 | 1061 | kcb->jprobe_saved_regs = *regs; |
8533bbe9 MH |
1062 | kcb->jprobe_saved_sp = stack_addr(regs); |
1063 | addr = (unsigned long)(kcb->jprobe_saved_sp); | |
1064 | ||
1da177e4 LT |
1065 | /* |
1066 | * As Linus pointed out, gcc assumes that the callee | |
1067 | * owns the argument space and could overwrite it, e.g. | |
1068 | * tailcall optimization. So, to be absolutely safe | |
1069 | * we also save and restore enough stack bytes to cover | |
1070 | * the argument area. | |
9254139a DV |
1071 | * Use __memcpy() to avoid KASAN stack out-of-bounds reports as we copy |
1072 | * raw stack chunk with redzones: | |
1da177e4 | 1073 | */ |
9254139a | 1074 | __memcpy(kcb->jprobes_stack, (kprobe_opcode_t *)addr, MIN_STACK_SIZE(addr)); |
053de044 | 1075 | regs->flags &= ~X86_EFLAGS_IF; |
58dfe883 | 1076 | trace_hardirqs_off(); |
65ea5b03 | 1077 | regs->ip = (unsigned long)(jp->entry); |
237d28db SRRH |
1078 | |
1079 | /* | |
1080 | * jprobes use jprobe_return() which skips the normal return | |
1081 | * path of the function, and this messes up the accounting of the | |
1082 | * function graph tracer to get messed up. | |
1083 | * | |
1084 | * Pause function graph tracing while performing the jprobe function. | |
1085 | */ | |
1086 | pause_graph_tracing(); | |
1da177e4 LT |
1087 | return 1; |
1088 | } | |
9326638c | 1089 | NOKPROBE_SYMBOL(setjmp_pre_handler); |
1da177e4 | 1090 | |
9326638c | 1091 | void jprobe_return(void) |
1da177e4 | 1092 | { |
e7a510f9 AM |
1093 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
1094 | ||
9f7d416c DV |
1095 | /* Unpoison stack redzones in the frames we are going to jump over. */ |
1096 | kasan_unpoison_stack_above_sp_to(kcb->jprobe_saved_sp); | |
1097 | ||
d6be29b8 MH |
1098 | asm volatile ( |
1099 | #ifdef CONFIG_X86_64 | |
1100 | " xchg %%rbx,%%rsp \n" | |
1101 | #else | |
1102 | " xchgl %%ebx,%%esp \n" | |
1103 | #endif | |
1104 | " int3 \n" | |
1105 | " .globl jprobe_return_end\n" | |
1106 | " jprobe_return_end: \n" | |
1107 | " nop \n"::"b" | |
1108 | (kcb->jprobe_saved_sp):"memory"); | |
1da177e4 | 1109 | } |
9326638c MH |
1110 | NOKPROBE_SYMBOL(jprobe_return); |
1111 | NOKPROBE_SYMBOL(jprobe_return_end); | |
1da177e4 | 1112 | |
9326638c | 1113 | int longjmp_break_handler(struct kprobe *p, struct pt_regs *regs) |
1da177e4 | 1114 | { |
e7a510f9 | 1115 | struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
65ea5b03 | 1116 | u8 *addr = (u8 *) (regs->ip - 1); |
1da177e4 | 1117 | struct jprobe *jp = container_of(p, struct jprobe, kp); |
237d28db | 1118 | void *saved_sp = kcb->jprobe_saved_sp; |
1da177e4 | 1119 | |
d6be29b8 MH |
1120 | if ((addr > (u8 *) jprobe_return) && |
1121 | (addr < (u8 *) jprobe_return_end)) { | |
237d28db | 1122 | if (stack_addr(regs) != saved_sp) { |
29b6cd79 | 1123 | struct pt_regs *saved_regs = &kcb->jprobe_saved_regs; |
d6be29b8 MH |
1124 | printk(KERN_ERR |
1125 | "current sp %p does not match saved sp %p\n", | |
237d28db | 1126 | stack_addr(regs), saved_sp); |
d6be29b8 | 1127 | printk(KERN_ERR "Saved registers for jprobe %p\n", jp); |
57da8b96 | 1128 | show_regs(saved_regs); |
d6be29b8 | 1129 | printk(KERN_ERR "Current registers\n"); |
57da8b96 | 1130 | show_regs(regs); |
1da177e4 LT |
1131 | BUG(); |
1132 | } | |
237d28db SRRH |
1133 | /* It's OK to start function graph tracing again */ |
1134 | unpause_graph_tracing(); | |
e7a510f9 | 1135 | *regs = kcb->jprobe_saved_regs; |
9254139a | 1136 | __memcpy(saved_sp, kcb->jprobes_stack, MIN_STACK_SIZE(saved_sp)); |
d217d545 | 1137 | preempt_enable_no_resched(); |
1da177e4 LT |
1138 | return 1; |
1139 | } | |
1140 | return 0; | |
1141 | } | |
9326638c | 1142 | NOKPROBE_SYMBOL(longjmp_break_handler); |
ba8af12f | 1143 | |
be8f2743 MH |
1144 | bool arch_within_kprobe_blacklist(unsigned long addr) |
1145 | { | |
1146 | return (addr >= (unsigned long)__kprobes_text_start && | |
1147 | addr < (unsigned long)__kprobes_text_end) || | |
1148 | (addr >= (unsigned long)__entry_text_start && | |
1149 | addr < (unsigned long)__entry_text_end); | |
1150 | } | |
1151 | ||
6772926b | 1152 | int __init arch_init_kprobes(void) |
ba8af12f | 1153 | { |
a7b0133e | 1154 | return 0; |
ba8af12f | 1155 | } |
bf8f6e5b | 1156 | |
7ec8a97a | 1157 | int arch_trampoline_kprobe(struct kprobe *p) |
bf8f6e5b | 1158 | { |
bf8f6e5b AM |
1159 | return 0; |
1160 | } |