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1#define pr_fmt(fmt) "SMP alternatives: " fmt
2
3#include <linux/module.h>
4#include <linux/sched.h>
5#include <linux/mutex.h>
6#include <linux/list.h>
7#include <linux/stringify.h>
8#include <linux/mm.h>
9#include <linux/vmalloc.h>
10#include <linux/memory.h>
11#include <linux/stop_machine.h>
12#include <linux/slab.h>
13#include <linux/kdebug.h>
14#include <asm/text-patching.h>
15#include <asm/alternative.h>
16#include <asm/sections.h>
17#include <asm/pgtable.h>
18#include <asm/mce.h>
19#include <asm/nmi.h>
20#include <asm/cacheflush.h>
21#include <asm/tlbflush.h>
22#include <asm/io.h>
23#include <asm/fixmap.h>
24
25int __read_mostly alternatives_patched;
26
27EXPORT_SYMBOL_GPL(alternatives_patched);
28
29#define MAX_PATCH_LEN (255-1)
30
31static int __initdata_or_module debug_alternative;
32
33static int __init debug_alt(char *str)
34{
35 debug_alternative = 1;
36 return 1;
37}
38__setup("debug-alternative", debug_alt);
39
40static int noreplace_smp;
41
42static int __init setup_noreplace_smp(char *str)
43{
44 noreplace_smp = 1;
45 return 1;
46}
47__setup("noreplace-smp", setup_noreplace_smp);
48
49#define DPRINTK(fmt, args...) \
50do { \
51 if (debug_alternative) \
52 printk(KERN_DEBUG "%s: " fmt "\n", __func__, ##args); \
53} while (0)
54
55#define DUMP_BYTES(buf, len, fmt, args...) \
56do { \
57 if (unlikely(debug_alternative)) { \
58 int j; \
59 \
60 if (!(len)) \
61 break; \
62 \
63 printk(KERN_DEBUG fmt, ##args); \
64 for (j = 0; j < (len) - 1; j++) \
65 printk(KERN_CONT "%02hhx ", buf[j]); \
66 printk(KERN_CONT "%02hhx\n", buf[j]); \
67 } \
68} while (0)
69
70/*
71 * Each GENERIC_NOPX is of X bytes, and defined as an array of bytes
72 * that correspond to that nop. Getting from one nop to the next, we
73 * add to the array the offset that is equal to the sum of all sizes of
74 * nops preceding the one we are after.
75 *
76 * Note: The GENERIC_NOP5_ATOMIC is at the end, as it breaks the
77 * nice symmetry of sizes of the previous nops.
78 */
79#if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64)
80static const unsigned char intelnops[] =
81{
82 GENERIC_NOP1,
83 GENERIC_NOP2,
84 GENERIC_NOP3,
85 GENERIC_NOP4,
86 GENERIC_NOP5,
87 GENERIC_NOP6,
88 GENERIC_NOP7,
89 GENERIC_NOP8,
90 GENERIC_NOP5_ATOMIC
91};
92static const unsigned char * const intel_nops[ASM_NOP_MAX+2] =
93{
94 NULL,
95 intelnops,
96 intelnops + 1,
97 intelnops + 1 + 2,
98 intelnops + 1 + 2 + 3,
99 intelnops + 1 + 2 + 3 + 4,
100 intelnops + 1 + 2 + 3 + 4 + 5,
101 intelnops + 1 + 2 + 3 + 4 + 5 + 6,
102 intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
103 intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
104};
105#endif
106
107#ifdef K8_NOP1
108static const unsigned char k8nops[] =
109{
110 K8_NOP1,
111 K8_NOP2,
112 K8_NOP3,
113 K8_NOP4,
114 K8_NOP5,
115 K8_NOP6,
116 K8_NOP7,
117 K8_NOP8,
118 K8_NOP5_ATOMIC
119};
120static const unsigned char * const k8_nops[ASM_NOP_MAX+2] =
121{
122 NULL,
123 k8nops,
124 k8nops + 1,
125 k8nops + 1 + 2,
126 k8nops + 1 + 2 + 3,
127 k8nops + 1 + 2 + 3 + 4,
128 k8nops + 1 + 2 + 3 + 4 + 5,
129 k8nops + 1 + 2 + 3 + 4 + 5 + 6,
130 k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
131 k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
132};
133#endif
134
135#if defined(K7_NOP1) && !defined(CONFIG_X86_64)
136static const unsigned char k7nops[] =
137{
138 K7_NOP1,
139 K7_NOP2,
140 K7_NOP3,
141 K7_NOP4,
142 K7_NOP5,
143 K7_NOP6,
144 K7_NOP7,
145 K7_NOP8,
146 K7_NOP5_ATOMIC
147};
148static const unsigned char * const k7_nops[ASM_NOP_MAX+2] =
149{
150 NULL,
151 k7nops,
152 k7nops + 1,
153 k7nops + 1 + 2,
154 k7nops + 1 + 2 + 3,
155 k7nops + 1 + 2 + 3 + 4,
156 k7nops + 1 + 2 + 3 + 4 + 5,
157 k7nops + 1 + 2 + 3 + 4 + 5 + 6,
158 k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
159 k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
160};
161#endif
162
163#ifdef P6_NOP1
164static const unsigned char p6nops[] =
165{
166 P6_NOP1,
167 P6_NOP2,
168 P6_NOP3,
169 P6_NOP4,
170 P6_NOP5,
171 P6_NOP6,
172 P6_NOP7,
173 P6_NOP8,
174 P6_NOP5_ATOMIC
175};
176static const unsigned char * const p6_nops[ASM_NOP_MAX+2] =
177{
178 NULL,
179 p6nops,
180 p6nops + 1,
181 p6nops + 1 + 2,
182 p6nops + 1 + 2 + 3,
183 p6nops + 1 + 2 + 3 + 4,
184 p6nops + 1 + 2 + 3 + 4 + 5,
185 p6nops + 1 + 2 + 3 + 4 + 5 + 6,
186 p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
187 p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
188};
189#endif
190
191/* Initialize these to a safe default */
192#ifdef CONFIG_X86_64
193const unsigned char * const *ideal_nops = p6_nops;
194#else
195const unsigned char * const *ideal_nops = intel_nops;
196#endif
197
198void __init arch_init_ideal_nops(void)
199{
200 switch (boot_cpu_data.x86_vendor) {
201 case X86_VENDOR_INTEL:
202 /*
203 * Due to a decoder implementation quirk, some
204 * specific Intel CPUs actually perform better with
205 * the "k8_nops" than with the SDM-recommended NOPs.
206 */
207 if (boot_cpu_data.x86 == 6 &&
208 boot_cpu_data.x86_model >= 0x0f &&
209 boot_cpu_data.x86_model != 0x1c &&
210 boot_cpu_data.x86_model != 0x26 &&
211 boot_cpu_data.x86_model != 0x27 &&
212 boot_cpu_data.x86_model < 0x30) {
213 ideal_nops = k8_nops;
214 } else if (boot_cpu_has(X86_FEATURE_NOPL)) {
215 ideal_nops = p6_nops;
216 } else {
217#ifdef CONFIG_X86_64
218 ideal_nops = k8_nops;
219#else
220 ideal_nops = intel_nops;
221#endif
222 }
223 break;
224
225 case X86_VENDOR_AMD:
226 if (boot_cpu_data.x86 > 0xf) {
227 ideal_nops = p6_nops;
228 return;
229 }
230
231 /* fall through */
232
233 default:
234#ifdef CONFIG_X86_64
235 ideal_nops = k8_nops;
236#else
237 if (boot_cpu_has(X86_FEATURE_K8))
238 ideal_nops = k8_nops;
239 else if (boot_cpu_has(X86_FEATURE_K7))
240 ideal_nops = k7_nops;
241 else
242 ideal_nops = intel_nops;
243#endif
244 }
245}
246
247/* Use this to add nops to a buffer, then text_poke the whole buffer. */
248static void __init_or_module add_nops(void *insns, unsigned int len)
249{
250 while (len > 0) {
251 unsigned int noplen = len;
252 if (noplen > ASM_NOP_MAX)
253 noplen = ASM_NOP_MAX;
254 memcpy(insns, ideal_nops[noplen], noplen);
255 insns += noplen;
256 len -= noplen;
257 }
258}
259
260extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
261extern s32 __smp_locks[], __smp_locks_end[];
262void *text_poke_early(void *addr, const void *opcode, size_t len);
263
264/*
265 * Are we looking at a near JMP with a 1 or 4-byte displacement.
266 */
267static inline bool is_jmp(const u8 opcode)
268{
269 return opcode == 0xeb || opcode == 0xe9;
270}
271
272static void __init_or_module
273recompute_jump(struct alt_instr *a, u8 *orig_insn, u8 *repl_insn, u8 *insnbuf)
274{
275 u8 *next_rip, *tgt_rip;
276 s32 n_dspl, o_dspl;
277 int repl_len;
278
279 if (a->replacementlen != 5)
280 return;
281
282 o_dspl = *(s32 *)(insnbuf + 1);
283
284 /* next_rip of the replacement JMP */
285 next_rip = repl_insn + a->replacementlen;
286 /* target rip of the replacement JMP */
287 tgt_rip = next_rip + o_dspl;
288 n_dspl = tgt_rip - orig_insn;
289
290 DPRINTK("target RIP: %px, new_displ: 0x%x", tgt_rip, n_dspl);
291
292 if (tgt_rip - orig_insn >= 0) {
293 if (n_dspl - 2 <= 127)
294 goto two_byte_jmp;
295 else
296 goto five_byte_jmp;
297 /* negative offset */
298 } else {
299 if (((n_dspl - 2) & 0xff) == (n_dspl - 2))
300 goto two_byte_jmp;
301 else
302 goto five_byte_jmp;
303 }
304
305two_byte_jmp:
306 n_dspl -= 2;
307
308 insnbuf[0] = 0xeb;
309 insnbuf[1] = (s8)n_dspl;
310 add_nops(insnbuf + 2, 3);
311
312 repl_len = 2;
313 goto done;
314
315five_byte_jmp:
316 n_dspl -= 5;
317
318 insnbuf[0] = 0xe9;
319 *(s32 *)&insnbuf[1] = n_dspl;
320
321 repl_len = 5;
322
323done:
324
325 DPRINTK("final displ: 0x%08x, JMP 0x%lx",
326 n_dspl, (unsigned long)orig_insn + n_dspl + repl_len);
327}
328
329/*
330 * "noinline" to cause control flow change and thus invalidate I$ and
331 * cause refetch after modification.
332 */
333static void __init_or_module noinline optimize_nops(struct alt_instr *a, u8 *instr)
334{
335 unsigned long flags;
336 int i;
337
338 for (i = 0; i < a->padlen; i++) {
339 if (instr[i] != 0x90)
340 return;
341 }
342
343 local_irq_save(flags);
344 add_nops(instr + (a->instrlen - a->padlen), a->padlen);
345 local_irq_restore(flags);
346
347 DUMP_BYTES(instr, a->instrlen, "%px: [%d:%d) optimized NOPs: ",
348 instr, a->instrlen - a->padlen, a->padlen);
349}
350
351/*
352 * Replace instructions with better alternatives for this CPU type. This runs
353 * before SMP is initialized to avoid SMP problems with self modifying code.
354 * This implies that asymmetric systems where APs have less capabilities than
355 * the boot processor are not handled. Tough. Make sure you disable such
356 * features by hand.
357 *
358 * Marked "noinline" to cause control flow change and thus insn cache
359 * to refetch changed I$ lines.
360 */
361void __init_or_module noinline apply_alternatives(struct alt_instr *start,
362 struct alt_instr *end)
363{
364 struct alt_instr *a;
365 u8 *instr, *replacement;
366 u8 insnbuf[MAX_PATCH_LEN];
367
368 DPRINTK("alt table %px, -> %px", start, end);
369 /*
370 * The scan order should be from start to end. A later scanned
371 * alternative code can overwrite previously scanned alternative code.
372 * Some kernel functions (e.g. memcpy, memset, etc) use this order to
373 * patch code.
374 *
375 * So be careful if you want to change the scan order to any other
376 * order.
377 */
378 for (a = start; a < end; a++) {
379 int insnbuf_sz = 0;
380
381 instr = (u8 *)&a->instr_offset + a->instr_offset;
382 replacement = (u8 *)&a->repl_offset + a->repl_offset;
383 BUG_ON(a->instrlen > sizeof(insnbuf));
384 BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32);
385 if (!boot_cpu_has(a->cpuid)) {
386 if (a->padlen > 1)
387 optimize_nops(a, instr);
388
389 continue;
390 }
391
392 DPRINTK("feat: %d*32+%d, old: (%px len: %d), repl: (%px, len: %d), pad: %d",
393 a->cpuid >> 5,
394 a->cpuid & 0x1f,
395 instr, a->instrlen,
396 replacement, a->replacementlen, a->padlen);
397
398 DUMP_BYTES(instr, a->instrlen, "%px: old_insn: ", instr);
399 DUMP_BYTES(replacement, a->replacementlen, "%px: rpl_insn: ", replacement);
400
401 memcpy(insnbuf, replacement, a->replacementlen);
402 insnbuf_sz = a->replacementlen;
403
404 /*
405 * 0xe8 is a relative jump; fix the offset.
406 *
407 * Instruction length is checked before the opcode to avoid
408 * accessing uninitialized bytes for zero-length replacements.
409 */
410 if (a->replacementlen == 5 && *insnbuf == 0xe8) {
411 *(s32 *)(insnbuf + 1) += replacement - instr;
412 DPRINTK("Fix CALL offset: 0x%x, CALL 0x%lx",
413 *(s32 *)(insnbuf + 1),
414 (unsigned long)instr + *(s32 *)(insnbuf + 1) + 5);
415 }
416
417 if (a->replacementlen && is_jmp(replacement[0]))
418 recompute_jump(a, instr, replacement, insnbuf);
419
420 if (a->instrlen > a->replacementlen) {
421 add_nops(insnbuf + a->replacementlen,
422 a->instrlen - a->replacementlen);
423 insnbuf_sz += a->instrlen - a->replacementlen;
424 }
425 DUMP_BYTES(insnbuf, insnbuf_sz, "%px: final_insn: ", instr);
426
427 text_poke_early(instr, insnbuf, insnbuf_sz);
428 }
429}
430
431#ifdef CONFIG_SMP
432static void alternatives_smp_lock(const s32 *start, const s32 *end,
433 u8 *text, u8 *text_end)
434{
435 const s32 *poff;
436
437 for (poff = start; poff < end; poff++) {
438 u8 *ptr = (u8 *)poff + *poff;
439
440 if (!*poff || ptr < text || ptr >= text_end)
441 continue;
442 /* turn DS segment override prefix into lock prefix */
443 if (*ptr == 0x3e)
444 text_poke(ptr, ((unsigned char []){0xf0}), 1);
445 }
446}
447
448static void alternatives_smp_unlock(const s32 *start, const s32 *end,
449 u8 *text, u8 *text_end)
450{
451 const s32 *poff;
452
453 for (poff = start; poff < end; poff++) {
454 u8 *ptr = (u8 *)poff + *poff;
455
456 if (!*poff || ptr < text || ptr >= text_end)
457 continue;
458 /* turn lock prefix into DS segment override prefix */
459 if (*ptr == 0xf0)
460 text_poke(ptr, ((unsigned char []){0x3E}), 1);
461 }
462}
463
464struct smp_alt_module {
465 /* what is this ??? */
466 struct module *mod;
467 char *name;
468
469 /* ptrs to lock prefixes */
470 const s32 *locks;
471 const s32 *locks_end;
472
473 /* .text segment, needed to avoid patching init code ;) */
474 u8 *text;
475 u8 *text_end;
476
477 struct list_head next;
478};
479static LIST_HEAD(smp_alt_modules);
480static bool uniproc_patched = false; /* protected by text_mutex */
481
482void __init_or_module alternatives_smp_module_add(struct module *mod,
483 char *name,
484 void *locks, void *locks_end,
485 void *text, void *text_end)
486{
487 struct smp_alt_module *smp;
488
489 mutex_lock(&text_mutex);
490 if (!uniproc_patched)
491 goto unlock;
492
493 if (num_possible_cpus() == 1)
494 /* Don't bother remembering, we'll never have to undo it. */
495 goto smp_unlock;
496
497 smp = kzalloc(sizeof(*smp), GFP_KERNEL);
498 if (NULL == smp)
499 /* we'll run the (safe but slow) SMP code then ... */
500 goto unlock;
501
502 smp->mod = mod;
503 smp->name = name;
504 smp->locks = locks;
505 smp->locks_end = locks_end;
506 smp->text = text;
507 smp->text_end = text_end;
508 DPRINTK("locks %p -> %p, text %p -> %p, name %s\n",
509 smp->locks, smp->locks_end,
510 smp->text, smp->text_end, smp->name);
511
512 list_add_tail(&smp->next, &smp_alt_modules);
513smp_unlock:
514 alternatives_smp_unlock(locks, locks_end, text, text_end);
515unlock:
516 mutex_unlock(&text_mutex);
517}
518
519void __init_or_module alternatives_smp_module_del(struct module *mod)
520{
521 struct smp_alt_module *item;
522
523 mutex_lock(&text_mutex);
524 list_for_each_entry(item, &smp_alt_modules, next) {
525 if (mod != item->mod)
526 continue;
527 list_del(&item->next);
528 kfree(item);
529 break;
530 }
531 mutex_unlock(&text_mutex);
532}
533
534void alternatives_enable_smp(void)
535{
536 struct smp_alt_module *mod;
537
538 /* Why bother if there are no other CPUs? */
539 BUG_ON(num_possible_cpus() == 1);
540
541 mutex_lock(&text_mutex);
542
543 if (uniproc_patched) {
544 pr_info("switching to SMP code\n");
545 BUG_ON(num_online_cpus() != 1);
546 clear_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
547 clear_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
548 list_for_each_entry(mod, &smp_alt_modules, next)
549 alternatives_smp_lock(mod->locks, mod->locks_end,
550 mod->text, mod->text_end);
551 uniproc_patched = false;
552 }
553 mutex_unlock(&text_mutex);
554}
555
556/*
557 * Return 1 if the address range is reserved for SMP-alternatives.
558 * Must hold text_mutex.
559 */
560int alternatives_text_reserved(void *start, void *end)
561{
562 struct smp_alt_module *mod;
563 const s32 *poff;
564 u8 *text_start = start;
565 u8 *text_end = end;
566
567 lockdep_assert_held(&text_mutex);
568
569 list_for_each_entry(mod, &smp_alt_modules, next) {
570 if (mod->text > text_end || mod->text_end < text_start)
571 continue;
572 for (poff = mod->locks; poff < mod->locks_end; poff++) {
573 const u8 *ptr = (const u8 *)poff + *poff;
574
575 if (text_start <= ptr && text_end > ptr)
576 return 1;
577 }
578 }
579
580 return 0;
581}
582#endif /* CONFIG_SMP */
583
584#ifdef CONFIG_PARAVIRT
585void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
586 struct paravirt_patch_site *end)
587{
588 struct paravirt_patch_site *p;
589 char insnbuf[MAX_PATCH_LEN];
590
591 for (p = start; p < end; p++) {
592 unsigned int used;
593
594 BUG_ON(p->len > MAX_PATCH_LEN);
595 /* prep the buffer with the original instructions */
596 memcpy(insnbuf, p->instr, p->len);
597 used = pv_init_ops.patch(p->instrtype, p->clobbers, insnbuf,
598 (unsigned long)p->instr, p->len);
599
600 BUG_ON(used > p->len);
601
602 /* Pad the rest with nops */
603 add_nops(insnbuf + used, p->len - used);
604 text_poke_early(p->instr, insnbuf, p->len);
605 }
606}
607extern struct paravirt_patch_site __start_parainstructions[],
608 __stop_parainstructions[];
609#endif /* CONFIG_PARAVIRT */
610
611void __init alternative_instructions(void)
612{
613 /* The patching is not fully atomic, so try to avoid local interruptions
614 that might execute the to be patched code.
615 Other CPUs are not running. */
616 stop_nmi();
617
618 /*
619 * Don't stop machine check exceptions while patching.
620 * MCEs only happen when something got corrupted and in this
621 * case we must do something about the corruption.
622 * Ignoring it is worse than a unlikely patching race.
623 * Also machine checks tend to be broadcast and if one CPU
624 * goes into machine check the others follow quickly, so we don't
625 * expect a machine check to cause undue problems during to code
626 * patching.
627 */
628
629 apply_alternatives(__alt_instructions, __alt_instructions_end);
630
631#ifdef CONFIG_SMP
632 /* Patch to UP if other cpus not imminent. */
633 if (!noreplace_smp && (num_present_cpus() == 1 || setup_max_cpus <= 1)) {
634 uniproc_patched = true;
635 alternatives_smp_module_add(NULL, "core kernel",
636 __smp_locks, __smp_locks_end,
637 _text, _etext);
638 }
639
640 if (!uniproc_patched || num_possible_cpus() == 1)
641 free_init_pages("SMP alternatives",
642 (unsigned long)__smp_locks,
643 (unsigned long)__smp_locks_end);
644#endif
645
646 apply_paravirt(__parainstructions, __parainstructions_end);
647
648 restart_nmi();
649 alternatives_patched = 1;
650}
651
652/**
653 * text_poke_early - Update instructions on a live kernel at boot time
654 * @addr: address to modify
655 * @opcode: source of the copy
656 * @len: length to copy
657 *
658 * When you use this code to patch more than one byte of an instruction
659 * you need to make sure that other CPUs cannot execute this code in parallel.
660 * Also no thread must be currently preempted in the middle of these
661 * instructions. And on the local CPU you need to be protected again NMI or MCE
662 * handlers seeing an inconsistent instruction while you patch.
663 */
664void *__init_or_module text_poke_early(void *addr, const void *opcode,
665 size_t len)
666{
667 unsigned long flags;
668 local_irq_save(flags);
669 memcpy(addr, opcode, len);
670 local_irq_restore(flags);
671 /* Could also do a CLFLUSH here to speed up CPU recovery; but
672 that causes hangs on some VIA CPUs. */
673 return addr;
674}
675
676/**
677 * text_poke - Update instructions on a live kernel
678 * @addr: address to modify
679 * @opcode: source of the copy
680 * @len: length to copy
681 *
682 * Only atomic text poke/set should be allowed when not doing early patching.
683 * It means the size must be writable atomically and the address must be aligned
684 * in a way that permits an atomic write. It also makes sure we fit on a single
685 * page.
686 *
687 * Note: Must be called under text_mutex.
688 */
689void *text_poke(void *addr, const void *opcode, size_t len)
690{
691 unsigned long flags;
692 char *vaddr;
693 struct page *pages[2];
694 int i;
695
696 if (!core_kernel_text((unsigned long)addr)) {
697 pages[0] = vmalloc_to_page(addr);
698 pages[1] = vmalloc_to_page(addr + PAGE_SIZE);
699 } else {
700 pages[0] = virt_to_page(addr);
701 WARN_ON(!PageReserved(pages[0]));
702 pages[1] = virt_to_page(addr + PAGE_SIZE);
703 }
704 BUG_ON(!pages[0]);
705 local_irq_save(flags);
706 set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0]));
707 if (pages[1])
708 set_fixmap(FIX_TEXT_POKE1, page_to_phys(pages[1]));
709 vaddr = (char *)fix_to_virt(FIX_TEXT_POKE0);
710 memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
711 clear_fixmap(FIX_TEXT_POKE0);
712 if (pages[1])
713 clear_fixmap(FIX_TEXT_POKE1);
714 local_flush_tlb();
715 sync_core();
716 /* Could also do a CLFLUSH here to speed up CPU recovery; but
717 that causes hangs on some VIA CPUs. */
718 for (i = 0; i < len; i++)
719 BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]);
720 local_irq_restore(flags);
721 return addr;
722}
723
724static void do_sync_core(void *info)
725{
726 sync_core();
727}
728
729static bool bp_patching_in_progress;
730static void *bp_int3_handler, *bp_int3_addr;
731
732int poke_int3_handler(struct pt_regs *regs)
733{
734 /*
735 * Having observed our INT3 instruction, we now must observe
736 * bp_patching_in_progress.
737 *
738 * in_progress = TRUE INT3
739 * WMB RMB
740 * write INT3 if (in_progress)
741 *
742 * Idem for bp_int3_handler.
743 */
744 smp_rmb();
745
746 if (likely(!bp_patching_in_progress))
747 return 0;
748
749 if (user_mode(regs) || regs->ip != (unsigned long)bp_int3_addr)
750 return 0;
751
752 /* set up the specified breakpoint handler */
753 regs->ip = (unsigned long) bp_int3_handler;
754
755 return 1;
756
757}
758
759/**
760 * text_poke_bp() -- update instructions on live kernel on SMP
761 * @addr: address to patch
762 * @opcode: opcode of new instruction
763 * @len: length to copy
764 * @handler: address to jump to when the temporary breakpoint is hit
765 *
766 * Modify multi-byte instruction by using int3 breakpoint on SMP.
767 * We completely avoid stop_machine() here, and achieve the
768 * synchronization using int3 breakpoint.
769 *
770 * The way it is done:
771 * - add a int3 trap to the address that will be patched
772 * - sync cores
773 * - update all but the first byte of the patched range
774 * - sync cores
775 * - replace the first byte (int3) by the first byte of
776 * replacing opcode
777 * - sync cores
778 *
779 * Note: must be called under text_mutex.
780 */
781void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
782{
783 unsigned char int3 = 0xcc;
784
785 bp_int3_handler = handler;
786 bp_int3_addr = (u8 *)addr + sizeof(int3);
787 bp_patching_in_progress = true;
788 /*
789 * Corresponding read barrier in int3 notifier for making sure the
790 * in_progress and handler are correctly ordered wrt. patching.
791 */
792 smp_wmb();
793
794 text_poke(addr, &int3, sizeof(int3));
795
796 on_each_cpu(do_sync_core, NULL, 1);
797
798 if (len - sizeof(int3) > 0) {
799 /* patch all but the first byte */
800 text_poke((char *)addr + sizeof(int3),
801 (const char *) opcode + sizeof(int3),
802 len - sizeof(int3));
803 /*
804 * According to Intel, this core syncing is very likely
805 * not necessary and we'd be safe even without it. But
806 * better safe than sorry (plus there's not only Intel).
807 */
808 on_each_cpu(do_sync_core, NULL, 1);
809 }
810
811 /* patch the first byte */
812 text_poke(addr, opcode, sizeof(int3));
813
814 on_each_cpu(do_sync_core, NULL, 1);
815 /*
816 * sync_core() implies an smp_mb() and orders this store against
817 * the writing of the new instruction.
818 */
819 bp_patching_in_progress = false;
820
821 return addr;
822}
823
1// SPDX-License-Identifier: GPL-2.0-only
2#define pr_fmt(fmt) "SMP alternatives: " fmt
3
4#include <linux/module.h>
5#include <linux/sched.h>
6#include <linux/perf_event.h>
7#include <linux/mutex.h>
8#include <linux/list.h>
9#include <linux/stringify.h>
10#include <linux/highmem.h>
11#include <linux/mm.h>
12#include <linux/vmalloc.h>
13#include <linux/memory.h>
14#include <linux/stop_machine.h>
15#include <linux/slab.h>
16#include <linux/kdebug.h>
17#include <linux/kprobes.h>
18#include <linux/mmu_context.h>
19#include <linux/bsearch.h>
20#include <linux/sync_core.h>
21#include <asm/text-patching.h>
22#include <asm/alternative.h>
23#include <asm/sections.h>
24#include <asm/mce.h>
25#include <asm/nmi.h>
26#include <asm/cacheflush.h>
27#include <asm/tlbflush.h>
28#include <asm/insn.h>
29#include <asm/io.h>
30#include <asm/fixmap.h>
31
32int __read_mostly alternatives_patched;
33
34EXPORT_SYMBOL_GPL(alternatives_patched);
35
36#define MAX_PATCH_LEN (255-1)
37
38static int __initdata_or_module debug_alternative;
39
40static int __init debug_alt(char *str)
41{
42 debug_alternative = 1;
43 return 1;
44}
45__setup("debug-alternative", debug_alt);
46
47static int noreplace_smp;
48
49static int __init setup_noreplace_smp(char *str)
50{
51 noreplace_smp = 1;
52 return 1;
53}
54__setup("noreplace-smp", setup_noreplace_smp);
55
56#define DPRINTK(fmt, args...) \
57do { \
58 if (debug_alternative) \
59 printk(KERN_DEBUG pr_fmt(fmt) "\n", ##args); \
60} while (0)
61
62#define DUMP_BYTES(buf, len, fmt, args...) \
63do { \
64 if (unlikely(debug_alternative)) { \
65 int j; \
66 \
67 if (!(len)) \
68 break; \
69 \
70 printk(KERN_DEBUG pr_fmt(fmt), ##args); \
71 for (j = 0; j < (len) - 1; j++) \
72 printk(KERN_CONT "%02hhx ", buf[j]); \
73 printk(KERN_CONT "%02hhx\n", buf[j]); \
74 } \
75} while (0)
76
77/*
78 * Each GENERIC_NOPX is of X bytes, and defined as an array of bytes
79 * that correspond to that nop. Getting from one nop to the next, we
80 * add to the array the offset that is equal to the sum of all sizes of
81 * nops preceding the one we are after.
82 *
83 * Note: The GENERIC_NOP5_ATOMIC is at the end, as it breaks the
84 * nice symmetry of sizes of the previous nops.
85 */
86#if defined(GENERIC_NOP1) && !defined(CONFIG_X86_64)
87static const unsigned char intelnops[] =
88{
89 GENERIC_NOP1,
90 GENERIC_NOP2,
91 GENERIC_NOP3,
92 GENERIC_NOP4,
93 GENERIC_NOP5,
94 GENERIC_NOP6,
95 GENERIC_NOP7,
96 GENERIC_NOP8,
97 GENERIC_NOP5_ATOMIC
98};
99static const unsigned char * const intel_nops[ASM_NOP_MAX+2] =
100{
101 NULL,
102 intelnops,
103 intelnops + 1,
104 intelnops + 1 + 2,
105 intelnops + 1 + 2 + 3,
106 intelnops + 1 + 2 + 3 + 4,
107 intelnops + 1 + 2 + 3 + 4 + 5,
108 intelnops + 1 + 2 + 3 + 4 + 5 + 6,
109 intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
110 intelnops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
111};
112#endif
113
114#ifdef K8_NOP1
115static const unsigned char k8nops[] =
116{
117 K8_NOP1,
118 K8_NOP2,
119 K8_NOP3,
120 K8_NOP4,
121 K8_NOP5,
122 K8_NOP6,
123 K8_NOP7,
124 K8_NOP8,
125 K8_NOP5_ATOMIC
126};
127static const unsigned char * const k8_nops[ASM_NOP_MAX+2] =
128{
129 NULL,
130 k8nops,
131 k8nops + 1,
132 k8nops + 1 + 2,
133 k8nops + 1 + 2 + 3,
134 k8nops + 1 + 2 + 3 + 4,
135 k8nops + 1 + 2 + 3 + 4 + 5,
136 k8nops + 1 + 2 + 3 + 4 + 5 + 6,
137 k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
138 k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
139};
140#endif
141
142#if defined(K7_NOP1) && !defined(CONFIG_X86_64)
143static const unsigned char k7nops[] =
144{
145 K7_NOP1,
146 K7_NOP2,
147 K7_NOP3,
148 K7_NOP4,
149 K7_NOP5,
150 K7_NOP6,
151 K7_NOP7,
152 K7_NOP8,
153 K7_NOP5_ATOMIC
154};
155static const unsigned char * const k7_nops[ASM_NOP_MAX+2] =
156{
157 NULL,
158 k7nops,
159 k7nops + 1,
160 k7nops + 1 + 2,
161 k7nops + 1 + 2 + 3,
162 k7nops + 1 + 2 + 3 + 4,
163 k7nops + 1 + 2 + 3 + 4 + 5,
164 k7nops + 1 + 2 + 3 + 4 + 5 + 6,
165 k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
166 k7nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
167};
168#endif
169
170#ifdef P6_NOP1
171static const unsigned char p6nops[] =
172{
173 P6_NOP1,
174 P6_NOP2,
175 P6_NOP3,
176 P6_NOP4,
177 P6_NOP5,
178 P6_NOP6,
179 P6_NOP7,
180 P6_NOP8,
181 P6_NOP5_ATOMIC
182};
183static const unsigned char * const p6_nops[ASM_NOP_MAX+2] =
184{
185 NULL,
186 p6nops,
187 p6nops + 1,
188 p6nops + 1 + 2,
189 p6nops + 1 + 2 + 3,
190 p6nops + 1 + 2 + 3 + 4,
191 p6nops + 1 + 2 + 3 + 4 + 5,
192 p6nops + 1 + 2 + 3 + 4 + 5 + 6,
193 p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,
194 p6nops + 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8,
195};
196#endif
197
198/* Initialize these to a safe default */
199#ifdef CONFIG_X86_64
200const unsigned char * const *ideal_nops = p6_nops;
201#else
202const unsigned char * const *ideal_nops = intel_nops;
203#endif
204
205void __init arch_init_ideal_nops(void)
206{
207 switch (boot_cpu_data.x86_vendor) {
208 case X86_VENDOR_INTEL:
209 /*
210 * Due to a decoder implementation quirk, some
211 * specific Intel CPUs actually perform better with
212 * the "k8_nops" than with the SDM-recommended NOPs.
213 */
214 if (boot_cpu_data.x86 == 6 &&
215 boot_cpu_data.x86_model >= 0x0f &&
216 boot_cpu_data.x86_model != 0x1c &&
217 boot_cpu_data.x86_model != 0x26 &&
218 boot_cpu_data.x86_model != 0x27 &&
219 boot_cpu_data.x86_model < 0x30) {
220 ideal_nops = k8_nops;
221 } else if (boot_cpu_has(X86_FEATURE_NOPL)) {
222 ideal_nops = p6_nops;
223 } else {
224#ifdef CONFIG_X86_64
225 ideal_nops = k8_nops;
226#else
227 ideal_nops = intel_nops;
228#endif
229 }
230 break;
231
232 case X86_VENDOR_HYGON:
233 ideal_nops = p6_nops;
234 return;
235
236 case X86_VENDOR_AMD:
237 if (boot_cpu_data.x86 > 0xf) {
238 ideal_nops = p6_nops;
239 return;
240 }
241
242 fallthrough;
243
244 default:
245#ifdef CONFIG_X86_64
246 ideal_nops = k8_nops;
247#else
248 if (boot_cpu_has(X86_FEATURE_K8))
249 ideal_nops = k8_nops;
250 else if (boot_cpu_has(X86_FEATURE_K7))
251 ideal_nops = k7_nops;
252 else
253 ideal_nops = intel_nops;
254#endif
255 }
256}
257
258/* Use this to add nops to a buffer, then text_poke the whole buffer. */
259static void __init_or_module add_nops(void *insns, unsigned int len)
260{
261 while (len > 0) {
262 unsigned int noplen = len;
263 if (noplen > ASM_NOP_MAX)
264 noplen = ASM_NOP_MAX;
265 memcpy(insns, ideal_nops[noplen], noplen);
266 insns += noplen;
267 len -= noplen;
268 }
269}
270
271extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
272extern s32 __smp_locks[], __smp_locks_end[];
273void text_poke_early(void *addr, const void *opcode, size_t len);
274
275/*
276 * Are we looking at a near JMP with a 1 or 4-byte displacement.
277 */
278static inline bool is_jmp(const u8 opcode)
279{
280 return opcode == 0xeb || opcode == 0xe9;
281}
282
283static void __init_or_module
284recompute_jump(struct alt_instr *a, u8 *orig_insn, u8 *repl_insn, u8 *insn_buff)
285{
286 u8 *next_rip, *tgt_rip;
287 s32 n_dspl, o_dspl;
288 int repl_len;
289
290 if (a->replacementlen != 5)
291 return;
292
293 o_dspl = *(s32 *)(insn_buff + 1);
294
295 /* next_rip of the replacement JMP */
296 next_rip = repl_insn + a->replacementlen;
297 /* target rip of the replacement JMP */
298 tgt_rip = next_rip + o_dspl;
299 n_dspl = tgt_rip - orig_insn;
300
301 DPRINTK("target RIP: %px, new_displ: 0x%x", tgt_rip, n_dspl);
302
303 if (tgt_rip - orig_insn >= 0) {
304 if (n_dspl - 2 <= 127)
305 goto two_byte_jmp;
306 else
307 goto five_byte_jmp;
308 /* negative offset */
309 } else {
310 if (((n_dspl - 2) & 0xff) == (n_dspl - 2))
311 goto two_byte_jmp;
312 else
313 goto five_byte_jmp;
314 }
315
316two_byte_jmp:
317 n_dspl -= 2;
318
319 insn_buff[0] = 0xeb;
320 insn_buff[1] = (s8)n_dspl;
321 add_nops(insn_buff + 2, 3);
322
323 repl_len = 2;
324 goto done;
325
326five_byte_jmp:
327 n_dspl -= 5;
328
329 insn_buff[0] = 0xe9;
330 *(s32 *)&insn_buff[1] = n_dspl;
331
332 repl_len = 5;
333
334done:
335
336 DPRINTK("final displ: 0x%08x, JMP 0x%lx",
337 n_dspl, (unsigned long)orig_insn + n_dspl + repl_len);
338}
339
340/*
341 * "noinline" to cause control flow change and thus invalidate I$ and
342 * cause refetch after modification.
343 */
344static void __init_or_module noinline optimize_nops(struct alt_instr *a, u8 *instr)
345{
346 unsigned long flags;
347 int i;
348
349 for (i = 0; i < a->padlen; i++) {
350 if (instr[i] != 0x90)
351 return;
352 }
353
354 local_irq_save(flags);
355 add_nops(instr + (a->instrlen - a->padlen), a->padlen);
356 local_irq_restore(flags);
357
358 DUMP_BYTES(instr, a->instrlen, "%px: [%d:%d) optimized NOPs: ",
359 instr, a->instrlen - a->padlen, a->padlen);
360}
361
362/*
363 * Replace instructions with better alternatives for this CPU type. This runs
364 * before SMP is initialized to avoid SMP problems with self modifying code.
365 * This implies that asymmetric systems where APs have less capabilities than
366 * the boot processor are not handled. Tough. Make sure you disable such
367 * features by hand.
368 *
369 * Marked "noinline" to cause control flow change and thus insn cache
370 * to refetch changed I$ lines.
371 */
372void __init_or_module noinline apply_alternatives(struct alt_instr *start,
373 struct alt_instr *end)
374{
375 struct alt_instr *a;
376 u8 *instr, *replacement;
377 u8 insn_buff[MAX_PATCH_LEN];
378
379 DPRINTK("alt table %px, -> %px", start, end);
380 /*
381 * The scan order should be from start to end. A later scanned
382 * alternative code can overwrite previously scanned alternative code.
383 * Some kernel functions (e.g. memcpy, memset, etc) use this order to
384 * patch code.
385 *
386 * So be careful if you want to change the scan order to any other
387 * order.
388 */
389 for (a = start; a < end; a++) {
390 int insn_buff_sz = 0;
391
392 instr = (u8 *)&a->instr_offset + a->instr_offset;
393 replacement = (u8 *)&a->repl_offset + a->repl_offset;
394 BUG_ON(a->instrlen > sizeof(insn_buff));
395 BUG_ON(a->cpuid >= (NCAPINTS + NBUGINTS) * 32);
396 if (!boot_cpu_has(a->cpuid)) {
397 if (a->padlen > 1)
398 optimize_nops(a, instr);
399
400 continue;
401 }
402
403 DPRINTK("feat: %d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d), pad: %d",
404 a->cpuid >> 5,
405 a->cpuid & 0x1f,
406 instr, instr, a->instrlen,
407 replacement, a->replacementlen, a->padlen);
408
409 DUMP_BYTES(instr, a->instrlen, "%px: old_insn: ", instr);
410 DUMP_BYTES(replacement, a->replacementlen, "%px: rpl_insn: ", replacement);
411
412 memcpy(insn_buff, replacement, a->replacementlen);
413 insn_buff_sz = a->replacementlen;
414
415 /*
416 * 0xe8 is a relative jump; fix the offset.
417 *
418 * Instruction length is checked before the opcode to avoid
419 * accessing uninitialized bytes for zero-length replacements.
420 */
421 if (a->replacementlen == 5 && *insn_buff == 0xe8) {
422 *(s32 *)(insn_buff + 1) += replacement - instr;
423 DPRINTK("Fix CALL offset: 0x%x, CALL 0x%lx",
424 *(s32 *)(insn_buff + 1),
425 (unsigned long)instr + *(s32 *)(insn_buff + 1) + 5);
426 }
427
428 if (a->replacementlen && is_jmp(replacement[0]))
429 recompute_jump(a, instr, replacement, insn_buff);
430
431 if (a->instrlen > a->replacementlen) {
432 add_nops(insn_buff + a->replacementlen,
433 a->instrlen - a->replacementlen);
434 insn_buff_sz += a->instrlen - a->replacementlen;
435 }
436 DUMP_BYTES(insn_buff, insn_buff_sz, "%px: final_insn: ", instr);
437
438 text_poke_early(instr, insn_buff, insn_buff_sz);
439 }
440}
441
442#ifdef CONFIG_SMP
443static void alternatives_smp_lock(const s32 *start, const s32 *end,
444 u8 *text, u8 *text_end)
445{
446 const s32 *poff;
447
448 for (poff = start; poff < end; poff++) {
449 u8 *ptr = (u8 *)poff + *poff;
450
451 if (!*poff || ptr < text || ptr >= text_end)
452 continue;
453 /* turn DS segment override prefix into lock prefix */
454 if (*ptr == 0x3e)
455 text_poke(ptr, ((unsigned char []){0xf0}), 1);
456 }
457}
458
459static void alternatives_smp_unlock(const s32 *start, const s32 *end,
460 u8 *text, u8 *text_end)
461{
462 const s32 *poff;
463
464 for (poff = start; poff < end; poff++) {
465 u8 *ptr = (u8 *)poff + *poff;
466
467 if (!*poff || ptr < text || ptr >= text_end)
468 continue;
469 /* turn lock prefix into DS segment override prefix */
470 if (*ptr == 0xf0)
471 text_poke(ptr, ((unsigned char []){0x3E}), 1);
472 }
473}
474
475struct smp_alt_module {
476 /* what is this ??? */
477 struct module *mod;
478 char *name;
479
480 /* ptrs to lock prefixes */
481 const s32 *locks;
482 const s32 *locks_end;
483
484 /* .text segment, needed to avoid patching init code ;) */
485 u8 *text;
486 u8 *text_end;
487
488 struct list_head next;
489};
490static LIST_HEAD(smp_alt_modules);
491static bool uniproc_patched = false; /* protected by text_mutex */
492
493void __init_or_module alternatives_smp_module_add(struct module *mod,
494 char *name,
495 void *locks, void *locks_end,
496 void *text, void *text_end)
497{
498 struct smp_alt_module *smp;
499
500 mutex_lock(&text_mutex);
501 if (!uniproc_patched)
502 goto unlock;
503
504 if (num_possible_cpus() == 1)
505 /* Don't bother remembering, we'll never have to undo it. */
506 goto smp_unlock;
507
508 smp = kzalloc(sizeof(*smp), GFP_KERNEL);
509 if (NULL == smp)
510 /* we'll run the (safe but slow) SMP code then ... */
511 goto unlock;
512
513 smp->mod = mod;
514 smp->name = name;
515 smp->locks = locks;
516 smp->locks_end = locks_end;
517 smp->text = text;
518 smp->text_end = text_end;
519 DPRINTK("locks %p -> %p, text %p -> %p, name %s\n",
520 smp->locks, smp->locks_end,
521 smp->text, smp->text_end, smp->name);
522
523 list_add_tail(&smp->next, &smp_alt_modules);
524smp_unlock:
525 alternatives_smp_unlock(locks, locks_end, text, text_end);
526unlock:
527 mutex_unlock(&text_mutex);
528}
529
530void __init_or_module alternatives_smp_module_del(struct module *mod)
531{
532 struct smp_alt_module *item;
533
534 mutex_lock(&text_mutex);
535 list_for_each_entry(item, &smp_alt_modules, next) {
536 if (mod != item->mod)
537 continue;
538 list_del(&item->next);
539 kfree(item);
540 break;
541 }
542 mutex_unlock(&text_mutex);
543}
544
545void alternatives_enable_smp(void)
546{
547 struct smp_alt_module *mod;
548
549 /* Why bother if there are no other CPUs? */
550 BUG_ON(num_possible_cpus() == 1);
551
552 mutex_lock(&text_mutex);
553
554 if (uniproc_patched) {
555 pr_info("switching to SMP code\n");
556 BUG_ON(num_online_cpus() != 1);
557 clear_cpu_cap(&boot_cpu_data, X86_FEATURE_UP);
558 clear_cpu_cap(&cpu_data(0), X86_FEATURE_UP);
559 list_for_each_entry(mod, &smp_alt_modules, next)
560 alternatives_smp_lock(mod->locks, mod->locks_end,
561 mod->text, mod->text_end);
562 uniproc_patched = false;
563 }
564 mutex_unlock(&text_mutex);
565}
566
567/*
568 * Return 1 if the address range is reserved for SMP-alternatives.
569 * Must hold text_mutex.
570 */
571int alternatives_text_reserved(void *start, void *end)
572{
573 struct smp_alt_module *mod;
574 const s32 *poff;
575 u8 *text_start = start;
576 u8 *text_end = end;
577
578 lockdep_assert_held(&text_mutex);
579
580 list_for_each_entry(mod, &smp_alt_modules, next) {
581 if (mod->text > text_end || mod->text_end < text_start)
582 continue;
583 for (poff = mod->locks; poff < mod->locks_end; poff++) {
584 const u8 *ptr = (const u8 *)poff + *poff;
585
586 if (text_start <= ptr && text_end > ptr)
587 return 1;
588 }
589 }
590
591 return 0;
592}
593#endif /* CONFIG_SMP */
594
595#ifdef CONFIG_PARAVIRT
596void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
597 struct paravirt_patch_site *end)
598{
599 struct paravirt_patch_site *p;
600 char insn_buff[MAX_PATCH_LEN];
601
602 for (p = start; p < end; p++) {
603 unsigned int used;
604
605 BUG_ON(p->len > MAX_PATCH_LEN);
606 /* prep the buffer with the original instructions */
607 memcpy(insn_buff, p->instr, p->len);
608 used = pv_ops.init.patch(p->type, insn_buff, (unsigned long)p->instr, p->len);
609
610 BUG_ON(used > p->len);
611
612 /* Pad the rest with nops */
613 add_nops(insn_buff + used, p->len - used);
614 text_poke_early(p->instr, insn_buff, p->len);
615 }
616}
617extern struct paravirt_patch_site __start_parainstructions[],
618 __stop_parainstructions[];
619#endif /* CONFIG_PARAVIRT */
620
621/*
622 * Self-test for the INT3 based CALL emulation code.
623 *
624 * This exercises int3_emulate_call() to make sure INT3 pt_regs are set up
625 * properly and that there is a stack gap between the INT3 frame and the
626 * previous context. Without this gap doing a virtual PUSH on the interrupted
627 * stack would corrupt the INT3 IRET frame.
628 *
629 * See entry_{32,64}.S for more details.
630 */
631
632/*
633 * We define the int3_magic() function in assembly to control the calling
634 * convention such that we can 'call' it from assembly.
635 */
636
637extern void int3_magic(unsigned int *ptr); /* defined in asm */
638
639asm (
640" .pushsection .init.text, \"ax\", @progbits\n"
641" .type int3_magic, @function\n"
642"int3_magic:\n"
643" movl $1, (%" _ASM_ARG1 ")\n"
644" ret\n"
645" .size int3_magic, .-int3_magic\n"
646" .popsection\n"
647);
648
649extern __initdata unsigned long int3_selftest_ip; /* defined in asm below */
650
651static int __init
652int3_exception_notify(struct notifier_block *self, unsigned long val, void *data)
653{
654 struct die_args *args = data;
655 struct pt_regs *regs = args->regs;
656
657 if (!regs || user_mode(regs))
658 return NOTIFY_DONE;
659
660 if (val != DIE_INT3)
661 return NOTIFY_DONE;
662
663 if (regs->ip - INT3_INSN_SIZE != int3_selftest_ip)
664 return NOTIFY_DONE;
665
666 int3_emulate_call(regs, (unsigned long)&int3_magic);
667 return NOTIFY_STOP;
668}
669
670static void __init int3_selftest(void)
671{
672 static __initdata struct notifier_block int3_exception_nb = {
673 .notifier_call = int3_exception_notify,
674 .priority = INT_MAX-1, /* last */
675 };
676 unsigned int val = 0;
677
678 BUG_ON(register_die_notifier(&int3_exception_nb));
679
680 /*
681 * Basically: int3_magic(&val); but really complicated :-)
682 *
683 * Stick the address of the INT3 instruction into int3_selftest_ip,
684 * then trigger the INT3, padded with NOPs to match a CALL instruction
685 * length.
686 */
687 asm volatile ("1: int3; nop; nop; nop; nop\n\t"
688 ".pushsection .init.data,\"aw\"\n\t"
689 ".align " __ASM_SEL(4, 8) "\n\t"
690 ".type int3_selftest_ip, @object\n\t"
691 ".size int3_selftest_ip, " __ASM_SEL(4, 8) "\n\t"
692 "int3_selftest_ip:\n\t"
693 __ASM_SEL(.long, .quad) " 1b\n\t"
694 ".popsection\n\t"
695 : ASM_CALL_CONSTRAINT
696 : __ASM_SEL_RAW(a, D) (&val)
697 : "memory");
698
699 BUG_ON(val != 1);
700
701 unregister_die_notifier(&int3_exception_nb);
702}
703
704void __init alternative_instructions(void)
705{
706 int3_selftest();
707
708 /*
709 * The patching is not fully atomic, so try to avoid local
710 * interruptions that might execute the to be patched code.
711 * Other CPUs are not running.
712 */
713 stop_nmi();
714
715 /*
716 * Don't stop machine check exceptions while patching.
717 * MCEs only happen when something got corrupted and in this
718 * case we must do something about the corruption.
719 * Ignoring it is worse than an unlikely patching race.
720 * Also machine checks tend to be broadcast and if one CPU
721 * goes into machine check the others follow quickly, so we don't
722 * expect a machine check to cause undue problems during to code
723 * patching.
724 */
725
726 apply_alternatives(__alt_instructions, __alt_instructions_end);
727
728#ifdef CONFIG_SMP
729 /* Patch to UP if other cpus not imminent. */
730 if (!noreplace_smp && (num_present_cpus() == 1 || setup_max_cpus <= 1)) {
731 uniproc_patched = true;
732 alternatives_smp_module_add(NULL, "core kernel",
733 __smp_locks, __smp_locks_end,
734 _text, _etext);
735 }
736
737 if (!uniproc_patched || num_possible_cpus() == 1) {
738 free_init_pages("SMP alternatives",
739 (unsigned long)__smp_locks,
740 (unsigned long)__smp_locks_end);
741 }
742#endif
743
744 apply_paravirt(__parainstructions, __parainstructions_end);
745
746 restart_nmi();
747 alternatives_patched = 1;
748}
749
750/**
751 * text_poke_early - Update instructions on a live kernel at boot time
752 * @addr: address to modify
753 * @opcode: source of the copy
754 * @len: length to copy
755 *
756 * When you use this code to patch more than one byte of an instruction
757 * you need to make sure that other CPUs cannot execute this code in parallel.
758 * Also no thread must be currently preempted in the middle of these
759 * instructions. And on the local CPU you need to be protected against NMI or
760 * MCE handlers seeing an inconsistent instruction while you patch.
761 */
762void __init_or_module text_poke_early(void *addr, const void *opcode,
763 size_t len)
764{
765 unsigned long flags;
766
767 if (boot_cpu_has(X86_FEATURE_NX) &&
768 is_module_text_address((unsigned long)addr)) {
769 /*
770 * Modules text is marked initially as non-executable, so the
771 * code cannot be running and speculative code-fetches are
772 * prevented. Just change the code.
773 */
774 memcpy(addr, opcode, len);
775 } else {
776 local_irq_save(flags);
777 memcpy(addr, opcode, len);
778 local_irq_restore(flags);
779 sync_core();
780
781 /*
782 * Could also do a CLFLUSH here to speed up CPU recovery; but
783 * that causes hangs on some VIA CPUs.
784 */
785 }
786}
787
788typedef struct {
789 struct mm_struct *mm;
790} temp_mm_state_t;
791
792/*
793 * Using a temporary mm allows to set temporary mappings that are not accessible
794 * by other CPUs. Such mappings are needed to perform sensitive memory writes
795 * that override the kernel memory protections (e.g., W^X), without exposing the
796 * temporary page-table mappings that are required for these write operations to
797 * other CPUs. Using a temporary mm also allows to avoid TLB shootdowns when the
798 * mapping is torn down.
799 *
800 * Context: The temporary mm needs to be used exclusively by a single core. To
801 * harden security IRQs must be disabled while the temporary mm is
802 * loaded, thereby preventing interrupt handler bugs from overriding
803 * the kernel memory protection.
804 */
805static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm)
806{
807 temp_mm_state_t temp_state;
808
809 lockdep_assert_irqs_disabled();
810 temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm);
811 switch_mm_irqs_off(NULL, mm, current);
812
813 /*
814 * If breakpoints are enabled, disable them while the temporary mm is
815 * used. Userspace might set up watchpoints on addresses that are used
816 * in the temporary mm, which would lead to wrong signals being sent or
817 * crashes.
818 *
819 * Note that breakpoints are not disabled selectively, which also causes
820 * kernel breakpoints (e.g., perf's) to be disabled. This might be
821 * undesirable, but still seems reasonable as the code that runs in the
822 * temporary mm should be short.
823 */
824 if (hw_breakpoint_active())
825 hw_breakpoint_disable();
826
827 return temp_state;
828}
829
830static inline void unuse_temporary_mm(temp_mm_state_t prev_state)
831{
832 lockdep_assert_irqs_disabled();
833 switch_mm_irqs_off(NULL, prev_state.mm, current);
834
835 /*
836 * Restore the breakpoints if they were disabled before the temporary mm
837 * was loaded.
838 */
839 if (hw_breakpoint_active())
840 hw_breakpoint_restore();
841}
842
843__ro_after_init struct mm_struct *poking_mm;
844__ro_after_init unsigned long poking_addr;
845
846static void *__text_poke(void *addr, const void *opcode, size_t len)
847{
848 bool cross_page_boundary = offset_in_page(addr) + len > PAGE_SIZE;
849 struct page *pages[2] = {NULL};
850 temp_mm_state_t prev;
851 unsigned long flags;
852 pte_t pte, *ptep;
853 spinlock_t *ptl;
854 pgprot_t pgprot;
855
856 /*
857 * While boot memory allocator is running we cannot use struct pages as
858 * they are not yet initialized. There is no way to recover.
859 */
860 BUG_ON(!after_bootmem);
861
862 if (!core_kernel_text((unsigned long)addr)) {
863 pages[0] = vmalloc_to_page(addr);
864 if (cross_page_boundary)
865 pages[1] = vmalloc_to_page(addr + PAGE_SIZE);
866 } else {
867 pages[0] = virt_to_page(addr);
868 WARN_ON(!PageReserved(pages[0]));
869 if (cross_page_boundary)
870 pages[1] = virt_to_page(addr + PAGE_SIZE);
871 }
872 /*
873 * If something went wrong, crash and burn since recovery paths are not
874 * implemented.
875 */
876 BUG_ON(!pages[0] || (cross_page_boundary && !pages[1]));
877
878 /*
879 * Map the page without the global bit, as TLB flushing is done with
880 * flush_tlb_mm_range(), which is intended for non-global PTEs.
881 */
882 pgprot = __pgprot(pgprot_val(PAGE_KERNEL) & ~_PAGE_GLOBAL);
883
884 /*
885 * The lock is not really needed, but this allows to avoid open-coding.
886 */
887 ptep = get_locked_pte(poking_mm, poking_addr, &ptl);
888
889 /*
890 * This must not fail; preallocated in poking_init().
891 */
892 VM_BUG_ON(!ptep);
893
894 local_irq_save(flags);
895
896 pte = mk_pte(pages[0], pgprot);
897 set_pte_at(poking_mm, poking_addr, ptep, pte);
898
899 if (cross_page_boundary) {
900 pte = mk_pte(pages[1], pgprot);
901 set_pte_at(poking_mm, poking_addr + PAGE_SIZE, ptep + 1, pte);
902 }
903
904 /*
905 * Loading the temporary mm behaves as a compiler barrier, which
906 * guarantees that the PTE will be set at the time memcpy() is done.
907 */
908 prev = use_temporary_mm(poking_mm);
909
910 kasan_disable_current();
911 memcpy((u8 *)poking_addr + offset_in_page(addr), opcode, len);
912 kasan_enable_current();
913
914 /*
915 * Ensure that the PTE is only cleared after the instructions of memcpy
916 * were issued by using a compiler barrier.
917 */
918 barrier();
919
920 pte_clear(poking_mm, poking_addr, ptep);
921 if (cross_page_boundary)
922 pte_clear(poking_mm, poking_addr + PAGE_SIZE, ptep + 1);
923
924 /*
925 * Loading the previous page-table hierarchy requires a serializing
926 * instruction that already allows the core to see the updated version.
927 * Xen-PV is assumed to serialize execution in a similar manner.
928 */
929 unuse_temporary_mm(prev);
930
931 /*
932 * Flushing the TLB might involve IPIs, which would require enabled
933 * IRQs, but not if the mm is not used, as it is in this point.
934 */
935 flush_tlb_mm_range(poking_mm, poking_addr, poking_addr +
936 (cross_page_boundary ? 2 : 1) * PAGE_SIZE,
937 PAGE_SHIFT, false);
938
939 /*
940 * If the text does not match what we just wrote then something is
941 * fundamentally screwy; there's nothing we can really do about that.
942 */
943 BUG_ON(memcmp(addr, opcode, len));
944
945 local_irq_restore(flags);
946 pte_unmap_unlock(ptep, ptl);
947 return addr;
948}
949
950/**
951 * text_poke - Update instructions on a live kernel
952 * @addr: address to modify
953 * @opcode: source of the copy
954 * @len: length to copy
955 *
956 * Only atomic text poke/set should be allowed when not doing early patching.
957 * It means the size must be writable atomically and the address must be aligned
958 * in a way that permits an atomic write. It also makes sure we fit on a single
959 * page.
960 *
961 * Note that the caller must ensure that if the modified code is part of a
962 * module, the module would not be removed during poking. This can be achieved
963 * by registering a module notifier, and ordering module removal and patching
964 * trough a mutex.
965 */
966void *text_poke(void *addr, const void *opcode, size_t len)
967{
968 lockdep_assert_held(&text_mutex);
969
970 return __text_poke(addr, opcode, len);
971}
972
973/**
974 * text_poke_kgdb - Update instructions on a live kernel by kgdb
975 * @addr: address to modify
976 * @opcode: source of the copy
977 * @len: length to copy
978 *
979 * Only atomic text poke/set should be allowed when not doing early patching.
980 * It means the size must be writable atomically and the address must be aligned
981 * in a way that permits an atomic write. It also makes sure we fit on a single
982 * page.
983 *
984 * Context: should only be used by kgdb, which ensures no other core is running,
985 * despite the fact it does not hold the text_mutex.
986 */
987void *text_poke_kgdb(void *addr, const void *opcode, size_t len)
988{
989 return __text_poke(addr, opcode, len);
990}
991
992static void do_sync_core(void *info)
993{
994 sync_core();
995}
996
997void text_poke_sync(void)
998{
999 on_each_cpu(do_sync_core, NULL, 1);
1000}
1001
1002struct text_poke_loc {
1003 s32 rel_addr; /* addr := _stext + rel_addr */
1004 s32 rel32;
1005 u8 opcode;
1006 const u8 text[POKE_MAX_OPCODE_SIZE];
1007 u8 old;
1008};
1009
1010struct bp_patching_desc {
1011 struct text_poke_loc *vec;
1012 int nr_entries;
1013 atomic_t refs;
1014};
1015
1016static struct bp_patching_desc *bp_desc;
1017
1018static __always_inline
1019struct bp_patching_desc *try_get_desc(struct bp_patching_desc **descp)
1020{
1021 struct bp_patching_desc *desc = __READ_ONCE(*descp); /* rcu_dereference */
1022
1023 if (!desc || !arch_atomic_inc_not_zero(&desc->refs))
1024 return NULL;
1025
1026 return desc;
1027}
1028
1029static __always_inline void put_desc(struct bp_patching_desc *desc)
1030{
1031 smp_mb__before_atomic();
1032 arch_atomic_dec(&desc->refs);
1033}
1034
1035static __always_inline void *text_poke_addr(struct text_poke_loc *tp)
1036{
1037 return _stext + tp->rel_addr;
1038}
1039
1040static __always_inline int patch_cmp(const void *key, const void *elt)
1041{
1042 struct text_poke_loc *tp = (struct text_poke_loc *) elt;
1043
1044 if (key < text_poke_addr(tp))
1045 return -1;
1046 if (key > text_poke_addr(tp))
1047 return 1;
1048 return 0;
1049}
1050
1051noinstr int poke_int3_handler(struct pt_regs *regs)
1052{
1053 struct bp_patching_desc *desc;
1054 struct text_poke_loc *tp;
1055 int len, ret = 0;
1056 void *ip;
1057
1058 if (user_mode(regs))
1059 return 0;
1060
1061 /*
1062 * Having observed our INT3 instruction, we now must observe
1063 * bp_desc:
1064 *
1065 * bp_desc = desc INT3
1066 * WMB RMB
1067 * write INT3 if (desc)
1068 */
1069 smp_rmb();
1070
1071 desc = try_get_desc(&bp_desc);
1072 if (!desc)
1073 return 0;
1074
1075 /*
1076 * Discount the INT3. See text_poke_bp_batch().
1077 */
1078 ip = (void *) regs->ip - INT3_INSN_SIZE;
1079
1080 /*
1081 * Skip the binary search if there is a single member in the vector.
1082 */
1083 if (unlikely(desc->nr_entries > 1)) {
1084 tp = __inline_bsearch(ip, desc->vec, desc->nr_entries,
1085 sizeof(struct text_poke_loc),
1086 patch_cmp);
1087 if (!tp)
1088 goto out_put;
1089 } else {
1090 tp = desc->vec;
1091 if (text_poke_addr(tp) != ip)
1092 goto out_put;
1093 }
1094
1095 len = text_opcode_size(tp->opcode);
1096 ip += len;
1097
1098 switch (tp->opcode) {
1099 case INT3_INSN_OPCODE:
1100 /*
1101 * Someone poked an explicit INT3, they'll want to handle it,
1102 * do not consume.
1103 */
1104 goto out_put;
1105
1106 case CALL_INSN_OPCODE:
1107 int3_emulate_call(regs, (long)ip + tp->rel32);
1108 break;
1109
1110 case JMP32_INSN_OPCODE:
1111 case JMP8_INSN_OPCODE:
1112 int3_emulate_jmp(regs, (long)ip + tp->rel32);
1113 break;
1114
1115 default:
1116 BUG();
1117 }
1118
1119 ret = 1;
1120
1121out_put:
1122 put_desc(desc);
1123 return ret;
1124}
1125
1126#define TP_VEC_MAX (PAGE_SIZE / sizeof(struct text_poke_loc))
1127static struct text_poke_loc tp_vec[TP_VEC_MAX];
1128static int tp_vec_nr;
1129
1130/**
1131 * text_poke_bp_batch() -- update instructions on live kernel on SMP
1132 * @tp: vector of instructions to patch
1133 * @nr_entries: number of entries in the vector
1134 *
1135 * Modify multi-byte instruction by using int3 breakpoint on SMP.
1136 * We completely avoid stop_machine() here, and achieve the
1137 * synchronization using int3 breakpoint.
1138 *
1139 * The way it is done:
1140 * - For each entry in the vector:
1141 * - add a int3 trap to the address that will be patched
1142 * - sync cores
1143 * - For each entry in the vector:
1144 * - update all but the first byte of the patched range
1145 * - sync cores
1146 * - For each entry in the vector:
1147 * - replace the first byte (int3) by the first byte of
1148 * replacing opcode
1149 * - sync cores
1150 */
1151static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries)
1152{
1153 struct bp_patching_desc desc = {
1154 .vec = tp,
1155 .nr_entries = nr_entries,
1156 .refs = ATOMIC_INIT(1),
1157 };
1158 unsigned char int3 = INT3_INSN_OPCODE;
1159 unsigned int i;
1160 int do_sync;
1161
1162 lockdep_assert_held(&text_mutex);
1163
1164 smp_store_release(&bp_desc, &desc); /* rcu_assign_pointer */
1165
1166 /*
1167 * Corresponding read barrier in int3 notifier for making sure the
1168 * nr_entries and handler are correctly ordered wrt. patching.
1169 */
1170 smp_wmb();
1171
1172 /*
1173 * First step: add a int3 trap to the address that will be patched.
1174 */
1175 for (i = 0; i < nr_entries; i++) {
1176 tp[i].old = *(u8 *)text_poke_addr(&tp[i]);
1177 text_poke(text_poke_addr(&tp[i]), &int3, INT3_INSN_SIZE);
1178 }
1179
1180 text_poke_sync();
1181
1182 /*
1183 * Second step: update all but the first byte of the patched range.
1184 */
1185 for (do_sync = 0, i = 0; i < nr_entries; i++) {
1186 u8 old[POKE_MAX_OPCODE_SIZE] = { tp[i].old, };
1187 int len = text_opcode_size(tp[i].opcode);
1188
1189 if (len - INT3_INSN_SIZE > 0) {
1190 memcpy(old + INT3_INSN_SIZE,
1191 text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
1192 len - INT3_INSN_SIZE);
1193 text_poke(text_poke_addr(&tp[i]) + INT3_INSN_SIZE,
1194 (const char *)tp[i].text + INT3_INSN_SIZE,
1195 len - INT3_INSN_SIZE);
1196 do_sync++;
1197 }
1198
1199 /*
1200 * Emit a perf event to record the text poke, primarily to
1201 * support Intel PT decoding which must walk the executable code
1202 * to reconstruct the trace. The flow up to here is:
1203 * - write INT3 byte
1204 * - IPI-SYNC
1205 * - write instruction tail
1206 * At this point the actual control flow will be through the
1207 * INT3 and handler and not hit the old or new instruction.
1208 * Intel PT outputs FUP/TIP packets for the INT3, so the flow
1209 * can still be decoded. Subsequently:
1210 * - emit RECORD_TEXT_POKE with the new instruction
1211 * - IPI-SYNC
1212 * - write first byte
1213 * - IPI-SYNC
1214 * So before the text poke event timestamp, the decoder will see
1215 * either the old instruction flow or FUP/TIP of INT3. After the
1216 * text poke event timestamp, the decoder will see either the
1217 * new instruction flow or FUP/TIP of INT3. Thus decoders can
1218 * use the timestamp as the point at which to modify the
1219 * executable code.
1220 * The old instruction is recorded so that the event can be
1221 * processed forwards or backwards.
1222 */
1223 perf_event_text_poke(text_poke_addr(&tp[i]), old, len,
1224 tp[i].text, len);
1225 }
1226
1227 if (do_sync) {
1228 /*
1229 * According to Intel, this core syncing is very likely
1230 * not necessary and we'd be safe even without it. But
1231 * better safe than sorry (plus there's not only Intel).
1232 */
1233 text_poke_sync();
1234 }
1235
1236 /*
1237 * Third step: replace the first byte (int3) by the first byte of
1238 * replacing opcode.
1239 */
1240 for (do_sync = 0, i = 0; i < nr_entries; i++) {
1241 if (tp[i].text[0] == INT3_INSN_OPCODE)
1242 continue;
1243
1244 text_poke(text_poke_addr(&tp[i]), tp[i].text, INT3_INSN_SIZE);
1245 do_sync++;
1246 }
1247
1248 if (do_sync)
1249 text_poke_sync();
1250
1251 /*
1252 * Remove and synchronize_rcu(), except we have a very primitive
1253 * refcount based completion.
1254 */
1255 WRITE_ONCE(bp_desc, NULL); /* RCU_INIT_POINTER */
1256 if (!atomic_dec_and_test(&desc.refs))
1257 atomic_cond_read_acquire(&desc.refs, !VAL);
1258}
1259
1260static void text_poke_loc_init(struct text_poke_loc *tp, void *addr,
1261 const void *opcode, size_t len, const void *emulate)
1262{
1263 struct insn insn;
1264
1265 memcpy((void *)tp->text, opcode, len);
1266 if (!emulate)
1267 emulate = opcode;
1268
1269 kernel_insn_init(&insn, emulate, MAX_INSN_SIZE);
1270 insn_get_length(&insn);
1271
1272 BUG_ON(!insn_complete(&insn));
1273 BUG_ON(len != insn.length);
1274
1275 tp->rel_addr = addr - (void *)_stext;
1276 tp->opcode = insn.opcode.bytes[0];
1277
1278 switch (tp->opcode) {
1279 case INT3_INSN_OPCODE:
1280 break;
1281
1282 case CALL_INSN_OPCODE:
1283 case JMP32_INSN_OPCODE:
1284 case JMP8_INSN_OPCODE:
1285 tp->rel32 = insn.immediate.value;
1286 break;
1287
1288 default: /* assume NOP */
1289 switch (len) {
1290 case 2: /* NOP2 -- emulate as JMP8+0 */
1291 BUG_ON(memcmp(emulate, ideal_nops[len], len));
1292 tp->opcode = JMP8_INSN_OPCODE;
1293 tp->rel32 = 0;
1294 break;
1295
1296 case 5: /* NOP5 -- emulate as JMP32+0 */
1297 BUG_ON(memcmp(emulate, ideal_nops[NOP_ATOMIC5], len));
1298 tp->opcode = JMP32_INSN_OPCODE;
1299 tp->rel32 = 0;
1300 break;
1301
1302 default: /* unknown instruction */
1303 BUG();
1304 }
1305 break;
1306 }
1307}
1308
1309/*
1310 * We hard rely on the tp_vec being ordered; ensure this is so by flushing
1311 * early if needed.
1312 */
1313static bool tp_order_fail(void *addr)
1314{
1315 struct text_poke_loc *tp;
1316
1317 if (!tp_vec_nr)
1318 return false;
1319
1320 if (!addr) /* force */
1321 return true;
1322
1323 tp = &tp_vec[tp_vec_nr - 1];
1324 if ((unsigned long)text_poke_addr(tp) > (unsigned long)addr)
1325 return true;
1326
1327 return false;
1328}
1329
1330static void text_poke_flush(void *addr)
1331{
1332 if (tp_vec_nr == TP_VEC_MAX || tp_order_fail(addr)) {
1333 text_poke_bp_batch(tp_vec, tp_vec_nr);
1334 tp_vec_nr = 0;
1335 }
1336}
1337
1338void text_poke_finish(void)
1339{
1340 text_poke_flush(NULL);
1341}
1342
1343void __ref text_poke_queue(void *addr, const void *opcode, size_t len, const void *emulate)
1344{
1345 struct text_poke_loc *tp;
1346
1347 if (unlikely(system_state == SYSTEM_BOOTING)) {
1348 text_poke_early(addr, opcode, len);
1349 return;
1350 }
1351
1352 text_poke_flush(addr);
1353
1354 tp = &tp_vec[tp_vec_nr++];
1355 text_poke_loc_init(tp, addr, opcode, len, emulate);
1356}
1357
1358/**
1359 * text_poke_bp() -- update instructions on live kernel on SMP
1360 * @addr: address to patch
1361 * @opcode: opcode of new instruction
1362 * @len: length to copy
1363 * @handler: address to jump to when the temporary breakpoint is hit
1364 *
1365 * Update a single instruction with the vector in the stack, avoiding
1366 * dynamically allocated memory. This function should be used when it is
1367 * not possible to allocate memory.
1368 */
1369void __ref text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate)
1370{
1371 struct text_poke_loc tp;
1372
1373 if (unlikely(system_state == SYSTEM_BOOTING)) {
1374 text_poke_early(addr, opcode, len);
1375 return;
1376 }
1377
1378 text_poke_loc_init(&tp, addr, opcode, len, emulate);
1379 text_poke_bp_batch(&tp, 1);
1380}