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1/*
2 * Copyright 2008 Michael Ellerman, IBM Corporation.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/kprobes.h>
12#include <linux/vmalloc.h>
13#include <linux/init.h>
14#include <linux/mm.h>
15#include <linux/cpuhotplug.h>
16#include <linux/slab.h>
17#include <linux/uaccess.h>
18#include <linux/kprobes.h>
19
20#include <asm/pgtable.h>
21#include <asm/tlbflush.h>
22#include <asm/page.h>
23#include <asm/code-patching.h>
24#include <asm/setup.h>
25
26static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
27 unsigned int *patch_addr)
28{
29 int err;
30
31 __put_user_size(instr, patch_addr, 4, err);
32 if (err)
33 return err;
34
35 asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
36 "r" (exec_addr));
37
38 return 0;
39}
40
41int raw_patch_instruction(unsigned int *addr, unsigned int instr)
42{
43 return __patch_instruction(addr, instr, addr);
44}
45
46#ifdef CONFIG_STRICT_KERNEL_RWX
47static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
48
49static int text_area_cpu_up(unsigned int cpu)
50{
51 struct vm_struct *area;
52
53 area = get_vm_area(PAGE_SIZE, VM_ALLOC);
54 if (!area) {
55 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
56 cpu);
57 return -1;
58 }
59 this_cpu_write(text_poke_area, area);
60
61 return 0;
62}
63
64static int text_area_cpu_down(unsigned int cpu)
65{
66 free_vm_area(this_cpu_read(text_poke_area));
67 return 0;
68}
69
70/*
71 * Run as a late init call. This allows all the boot time patching to be done
72 * simply by patching the code, and then we're called here prior to
73 * mark_rodata_ro(), which happens after all init calls are run. Although
74 * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
75 * it as being preferable to a kernel that will crash later when someone tries
76 * to use patch_instruction().
77 */
78static int __init setup_text_poke_area(void)
79{
80 BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
81 "powerpc/text_poke:online", text_area_cpu_up,
82 text_area_cpu_down));
83
84 return 0;
85}
86late_initcall(setup_text_poke_area);
87
88/*
89 * This can be called for kernel text or a module.
90 */
91static int map_patch_area(void *addr, unsigned long text_poke_addr)
92{
93 unsigned long pfn;
94 int err;
95
96 if (is_vmalloc_addr(addr))
97 pfn = vmalloc_to_pfn(addr);
98 else
99 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
100
101 err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT),
102 pgprot_val(PAGE_KERNEL));
103
104 pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
105 if (err)
106 return -1;
107
108 return 0;
109}
110
111static inline int unmap_patch_area(unsigned long addr)
112{
113 pte_t *ptep;
114 pmd_t *pmdp;
115 pud_t *pudp;
116 pgd_t *pgdp;
117
118 pgdp = pgd_offset_k(addr);
119 if (unlikely(!pgdp))
120 return -EINVAL;
121
122 pudp = pud_offset(pgdp, addr);
123 if (unlikely(!pudp))
124 return -EINVAL;
125
126 pmdp = pmd_offset(pudp, addr);
127 if (unlikely(!pmdp))
128 return -EINVAL;
129
130 ptep = pte_offset_kernel(pmdp, addr);
131 if (unlikely(!ptep))
132 return -EINVAL;
133
134 pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
135
136 /*
137 * In hash, pte_clear flushes the tlb, in radix, we have to
138 */
139 pte_clear(&init_mm, addr, ptep);
140 flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
141
142 return 0;
143}
144
145int patch_instruction(unsigned int *addr, unsigned int instr)
146{
147 int err;
148 unsigned int *patch_addr = NULL;
149 unsigned long flags;
150 unsigned long text_poke_addr;
151 unsigned long kaddr = (unsigned long)addr;
152
153 /*
154 * During early early boot patch_instruction is called
155 * when text_poke_area is not ready, but we still need
156 * to allow patching. We just do the plain old patching
157 */
158 if (!this_cpu_read(text_poke_area))
159 return raw_patch_instruction(addr, instr);
160
161 local_irq_save(flags);
162
163 text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
164 if (map_patch_area(addr, text_poke_addr)) {
165 err = -1;
166 goto out;
167 }
168
169 patch_addr = (unsigned int *)(text_poke_addr) +
170 ((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
171
172 __patch_instruction(addr, instr, patch_addr);
173
174 err = unmap_patch_area(text_poke_addr);
175 if (err)
176 pr_warn("failed to unmap %lx\n", text_poke_addr);
177
178out:
179 local_irq_restore(flags);
180
181 return err;
182}
183#else /* !CONFIG_STRICT_KERNEL_RWX */
184
185int patch_instruction(unsigned int *addr, unsigned int instr)
186{
187 return raw_patch_instruction(addr, instr);
188}
189
190#endif /* CONFIG_STRICT_KERNEL_RWX */
191NOKPROBE_SYMBOL(patch_instruction);
192
193int patch_branch(unsigned int *addr, unsigned long target, int flags)
194{
195 return patch_instruction(addr, create_branch(addr, target, flags));
196}
197
198bool is_offset_in_branch_range(long offset)
199{
200 /*
201 * Powerpc branch instruction is :
202 *
203 * 0 6 30 31
204 * +---------+----------------+---+---+
205 * | opcode | LI |AA |LK |
206 * +---------+----------------+---+---+
207 * Where AA = 0 and LK = 0
208 *
209 * LI is a signed 24 bits integer. The real branch offset is computed
210 * by: imm32 = SignExtend(LI:'0b00', 32);
211 *
212 * So the maximum forward branch should be:
213 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
214 * The maximum backward branch should be:
215 * (0xff800000 << 2) = 0xfe000000 = -0x2000000
216 */
217 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
218}
219
220/*
221 * Helper to check if a given instruction is a conditional branch
222 * Derived from the conditional checks in analyse_instr()
223 */
224bool is_conditional_branch(unsigned int instr)
225{
226 unsigned int opcode = instr >> 26;
227
228 if (opcode == 16) /* bc, bca, bcl, bcla */
229 return true;
230 if (opcode == 19) {
231 switch ((instr >> 1) & 0x3ff) {
232 case 16: /* bclr, bclrl */
233 case 528: /* bcctr, bcctrl */
234 case 560: /* bctar, bctarl */
235 return true;
236 }
237 }
238 return false;
239}
240NOKPROBE_SYMBOL(is_conditional_branch);
241
242unsigned int create_branch(const unsigned int *addr,
243 unsigned long target, int flags)
244{
245 unsigned int instruction;
246 long offset;
247
248 offset = target;
249 if (! (flags & BRANCH_ABSOLUTE))
250 offset = offset - (unsigned long)addr;
251
252 /* Check we can represent the target in the instruction format */
253 if (!is_offset_in_branch_range(offset))
254 return 0;
255
256 /* Mask out the flags and target, so they don't step on each other. */
257 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
258
259 return instruction;
260}
261
262unsigned int create_cond_branch(const unsigned int *addr,
263 unsigned long target, int flags)
264{
265 unsigned int instruction;
266 long offset;
267
268 offset = target;
269 if (! (flags & BRANCH_ABSOLUTE))
270 offset = offset - (unsigned long)addr;
271
272 /* Check we can represent the target in the instruction format */
273 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
274 return 0;
275
276 /* Mask out the flags and target, so they don't step on each other. */
277 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
278
279 return instruction;
280}
281
282static unsigned int branch_opcode(unsigned int instr)
283{
284 return (instr >> 26) & 0x3F;
285}
286
287static int instr_is_branch_iform(unsigned int instr)
288{
289 return branch_opcode(instr) == 18;
290}
291
292static int instr_is_branch_bform(unsigned int instr)
293{
294 return branch_opcode(instr) == 16;
295}
296
297int instr_is_relative_branch(unsigned int instr)
298{
299 if (instr & BRANCH_ABSOLUTE)
300 return 0;
301
302 return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
303}
304
305int instr_is_relative_link_branch(unsigned int instr)
306{
307 return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
308}
309
310static unsigned long branch_iform_target(const unsigned int *instr)
311{
312 signed long imm;
313
314 imm = *instr & 0x3FFFFFC;
315
316 /* If the top bit of the immediate value is set this is negative */
317 if (imm & 0x2000000)
318 imm -= 0x4000000;
319
320 if ((*instr & BRANCH_ABSOLUTE) == 0)
321 imm += (unsigned long)instr;
322
323 return (unsigned long)imm;
324}
325
326static unsigned long branch_bform_target(const unsigned int *instr)
327{
328 signed long imm;
329
330 imm = *instr & 0xFFFC;
331
332 /* If the top bit of the immediate value is set this is negative */
333 if (imm & 0x8000)
334 imm -= 0x10000;
335
336 if ((*instr & BRANCH_ABSOLUTE) == 0)
337 imm += (unsigned long)instr;
338
339 return (unsigned long)imm;
340}
341
342unsigned long branch_target(const unsigned int *instr)
343{
344 if (instr_is_branch_iform(*instr))
345 return branch_iform_target(instr);
346 else if (instr_is_branch_bform(*instr))
347 return branch_bform_target(instr);
348
349 return 0;
350}
351
352int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
353{
354 if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
355 return branch_target(instr) == addr;
356
357 return 0;
358}
359
360unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
361{
362 unsigned long target;
363
364 target = branch_target(src);
365
366 if (instr_is_branch_iform(*src))
367 return create_branch(dest, target, *src);
368 else if (instr_is_branch_bform(*src))
369 return create_cond_branch(dest, target, *src);
370
371 return 0;
372}
373
374#ifdef CONFIG_PPC_BOOK3E_64
375void __patch_exception(int exc, unsigned long addr)
376{
377 extern unsigned int interrupt_base_book3e;
378 unsigned int *ibase = &interrupt_base_book3e;
379
380 /* Our exceptions vectors start with a NOP and -then- a branch
381 * to deal with single stepping from userspace which stops on
382 * the second instruction. Thus we need to patch the second
383 * instruction of the exception, not the first one
384 */
385
386 patch_branch(ibase + (exc / 4) + 1, addr, 0);
387}
388#endif
389
390#ifdef CONFIG_CODE_PATCHING_SELFTEST
391
392static void __init test_trampoline(void)
393{
394 asm ("nop;\n");
395}
396
397#define check(x) \
398 if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
399
400static void __init test_branch_iform(void)
401{
402 unsigned int instr;
403 unsigned long addr;
404
405 addr = (unsigned long)&instr;
406
407 /* The simplest case, branch to self, no flags */
408 check(instr_is_branch_iform(0x48000000));
409 /* All bits of target set, and flags */
410 check(instr_is_branch_iform(0x4bffffff));
411 /* High bit of opcode set, which is wrong */
412 check(!instr_is_branch_iform(0xcbffffff));
413 /* Middle bits of opcode set, which is wrong */
414 check(!instr_is_branch_iform(0x7bffffff));
415
416 /* Simplest case, branch to self with link */
417 check(instr_is_branch_iform(0x48000001));
418 /* All bits of targets set */
419 check(instr_is_branch_iform(0x4bfffffd));
420 /* Some bits of targets set */
421 check(instr_is_branch_iform(0x4bff00fd));
422 /* Must be a valid branch to start with */
423 check(!instr_is_branch_iform(0x7bfffffd));
424
425 /* Absolute branch to 0x100 */
426 instr = 0x48000103;
427 check(instr_is_branch_to_addr(&instr, 0x100));
428 /* Absolute branch to 0x420fc */
429 instr = 0x480420ff;
430 check(instr_is_branch_to_addr(&instr, 0x420fc));
431 /* Maximum positive relative branch, + 20MB - 4B */
432 instr = 0x49fffffc;
433 check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
434 /* Smallest negative relative branch, - 4B */
435 instr = 0x4bfffffc;
436 check(instr_is_branch_to_addr(&instr, addr - 4));
437 /* Largest negative relative branch, - 32 MB */
438 instr = 0x4a000000;
439 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
440
441 /* Branch to self, with link */
442 instr = create_branch(&instr, addr, BRANCH_SET_LINK);
443 check(instr_is_branch_to_addr(&instr, addr));
444
445 /* Branch to self - 0x100, with link */
446 instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
447 check(instr_is_branch_to_addr(&instr, addr - 0x100));
448
449 /* Branch to self + 0x100, no link */
450 instr = create_branch(&instr, addr + 0x100, 0);
451 check(instr_is_branch_to_addr(&instr, addr + 0x100));
452
453 /* Maximum relative negative offset, - 32 MB */
454 instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
455 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
456
457 /* Out of range relative negative offset, - 32 MB + 4*/
458 instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
459 check(instr == 0);
460
461 /* Out of range relative positive offset, + 32 MB */
462 instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
463 check(instr == 0);
464
465 /* Unaligned target */
466 instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
467 check(instr == 0);
468
469 /* Check flags are masked correctly */
470 instr = create_branch(&instr, addr, 0xFFFFFFFC);
471 check(instr_is_branch_to_addr(&instr, addr));
472 check(instr == 0x48000000);
473}
474
475static void __init test_create_function_call(void)
476{
477 unsigned int *iptr;
478 unsigned long dest;
479
480 /* Check we can create a function call */
481 iptr = (unsigned int *)ppc_function_entry(test_trampoline);
482 dest = ppc_function_entry(test_create_function_call);
483 patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
484 check(instr_is_branch_to_addr(iptr, dest));
485}
486
487static void __init test_branch_bform(void)
488{
489 unsigned long addr;
490 unsigned int *iptr, instr, flags;
491
492 iptr = &instr;
493 addr = (unsigned long)iptr;
494
495 /* The simplest case, branch to self, no flags */
496 check(instr_is_branch_bform(0x40000000));
497 /* All bits of target set, and flags */
498 check(instr_is_branch_bform(0x43ffffff));
499 /* High bit of opcode set, which is wrong */
500 check(!instr_is_branch_bform(0xc3ffffff));
501 /* Middle bits of opcode set, which is wrong */
502 check(!instr_is_branch_bform(0x7bffffff));
503
504 /* Absolute conditional branch to 0x100 */
505 instr = 0x43ff0103;
506 check(instr_is_branch_to_addr(&instr, 0x100));
507 /* Absolute conditional branch to 0x20fc */
508 instr = 0x43ff20ff;
509 check(instr_is_branch_to_addr(&instr, 0x20fc));
510 /* Maximum positive relative conditional branch, + 32 KB - 4B */
511 instr = 0x43ff7ffc;
512 check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
513 /* Smallest negative relative conditional branch, - 4B */
514 instr = 0x43fffffc;
515 check(instr_is_branch_to_addr(&instr, addr - 4));
516 /* Largest negative relative conditional branch, - 32 KB */
517 instr = 0x43ff8000;
518 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
519
520 /* All condition code bits set & link */
521 flags = 0x3ff000 | BRANCH_SET_LINK;
522
523 /* Branch to self */
524 instr = create_cond_branch(iptr, addr, flags);
525 check(instr_is_branch_to_addr(&instr, addr));
526
527 /* Branch to self - 0x100 */
528 instr = create_cond_branch(iptr, addr - 0x100, flags);
529 check(instr_is_branch_to_addr(&instr, addr - 0x100));
530
531 /* Branch to self + 0x100 */
532 instr = create_cond_branch(iptr, addr + 0x100, flags);
533 check(instr_is_branch_to_addr(&instr, addr + 0x100));
534
535 /* Maximum relative negative offset, - 32 KB */
536 instr = create_cond_branch(iptr, addr - 0x8000, flags);
537 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
538
539 /* Out of range relative negative offset, - 32 KB + 4*/
540 instr = create_cond_branch(iptr, addr - 0x8004, flags);
541 check(instr == 0);
542
543 /* Out of range relative positive offset, + 32 KB */
544 instr = create_cond_branch(iptr, addr + 0x8000, flags);
545 check(instr == 0);
546
547 /* Unaligned target */
548 instr = create_cond_branch(iptr, addr + 3, flags);
549 check(instr == 0);
550
551 /* Check flags are masked correctly */
552 instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
553 check(instr_is_branch_to_addr(&instr, addr));
554 check(instr == 0x43FF0000);
555}
556
557static void __init test_translate_branch(void)
558{
559 unsigned long addr;
560 unsigned int *p, *q;
561 void *buf;
562
563 buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
564 check(buf);
565 if (!buf)
566 return;
567
568 /* Simple case, branch to self moved a little */
569 p = buf;
570 addr = (unsigned long)p;
571 patch_branch(p, addr, 0);
572 check(instr_is_branch_to_addr(p, addr));
573 q = p + 1;
574 patch_instruction(q, translate_branch(q, p));
575 check(instr_is_branch_to_addr(q, addr));
576
577 /* Maximum negative case, move b . to addr + 32 MB */
578 p = buf;
579 addr = (unsigned long)p;
580 patch_branch(p, addr, 0);
581 q = buf + 0x2000000;
582 patch_instruction(q, translate_branch(q, p));
583 check(instr_is_branch_to_addr(p, addr));
584 check(instr_is_branch_to_addr(q, addr));
585 check(*q == 0x4a000000);
586
587 /* Maximum positive case, move x to x - 32 MB + 4 */
588 p = buf + 0x2000000;
589 addr = (unsigned long)p;
590 patch_branch(p, addr, 0);
591 q = buf + 4;
592 patch_instruction(q, translate_branch(q, p));
593 check(instr_is_branch_to_addr(p, addr));
594 check(instr_is_branch_to_addr(q, addr));
595 check(*q == 0x49fffffc);
596
597 /* Jump to x + 16 MB moved to x + 20 MB */
598 p = buf;
599 addr = 0x1000000 + (unsigned long)buf;
600 patch_branch(p, addr, BRANCH_SET_LINK);
601 q = buf + 0x1400000;
602 patch_instruction(q, translate_branch(q, p));
603 check(instr_is_branch_to_addr(p, addr));
604 check(instr_is_branch_to_addr(q, addr));
605
606 /* Jump to x + 16 MB moved to x - 16 MB + 4 */
607 p = buf + 0x1000000;
608 addr = 0x2000000 + (unsigned long)buf;
609 patch_branch(p, addr, 0);
610 q = buf + 4;
611 patch_instruction(q, translate_branch(q, p));
612 check(instr_is_branch_to_addr(p, addr));
613 check(instr_is_branch_to_addr(q, addr));
614
615
616 /* Conditional branch tests */
617
618 /* Simple case, branch to self moved a little */
619 p = buf;
620 addr = (unsigned long)p;
621 patch_instruction(p, create_cond_branch(p, addr, 0));
622 check(instr_is_branch_to_addr(p, addr));
623 q = p + 1;
624 patch_instruction(q, translate_branch(q, p));
625 check(instr_is_branch_to_addr(q, addr));
626
627 /* Maximum negative case, move b . to addr + 32 KB */
628 p = buf;
629 addr = (unsigned long)p;
630 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
631 q = buf + 0x8000;
632 patch_instruction(q, translate_branch(q, p));
633 check(instr_is_branch_to_addr(p, addr));
634 check(instr_is_branch_to_addr(q, addr));
635 check(*q == 0x43ff8000);
636
637 /* Maximum positive case, move x to x - 32 KB + 4 */
638 p = buf + 0x8000;
639 addr = (unsigned long)p;
640 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
641 q = buf + 4;
642 patch_instruction(q, translate_branch(q, p));
643 check(instr_is_branch_to_addr(p, addr));
644 check(instr_is_branch_to_addr(q, addr));
645 check(*q == 0x43ff7ffc);
646
647 /* Jump to x + 12 KB moved to x + 20 KB */
648 p = buf;
649 addr = 0x3000 + (unsigned long)buf;
650 patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
651 q = buf + 0x5000;
652 patch_instruction(q, translate_branch(q, p));
653 check(instr_is_branch_to_addr(p, addr));
654 check(instr_is_branch_to_addr(q, addr));
655
656 /* Jump to x + 8 KB moved to x - 8 KB + 4 */
657 p = buf + 0x2000;
658 addr = 0x4000 + (unsigned long)buf;
659 patch_instruction(p, create_cond_branch(p, addr, 0));
660 q = buf + 4;
661 patch_instruction(q, translate_branch(q, p));
662 check(instr_is_branch_to_addr(p, addr));
663 check(instr_is_branch_to_addr(q, addr));
664
665 /* Free the buffer we were using */
666 vfree(buf);
667}
668
669static int __init test_code_patching(void)
670{
671 printk(KERN_DEBUG "Running code patching self-tests ...\n");
672
673 test_branch_iform();
674 test_branch_bform();
675 test_create_function_call();
676 test_translate_branch();
677
678 return 0;
679}
680late_initcall(test_code_patching);
681
682#endif /* CONFIG_CODE_PATCHING_SELFTEST */
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2008 Michael Ellerman, IBM Corporation.
4 */
5
6#include <linux/kernel.h>
7#include <linux/kprobes.h>
8#include <linux/vmalloc.h>
9#include <linux/init.h>
10#include <linux/mm.h>
11#include <linux/cpuhotplug.h>
12#include <linux/slab.h>
13#include <linux/uaccess.h>
14
15#include <asm/pgtable.h>
16#include <asm/tlbflush.h>
17#include <asm/page.h>
18#include <asm/code-patching.h>
19#include <asm/setup.h>
20
21static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
22 unsigned int *patch_addr)
23{
24 int err = 0;
25
26 __put_user_asm(instr, patch_addr, err, "stw");
27 if (err)
28 return err;
29
30 asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
31 "r" (exec_addr));
32
33 return 0;
34}
35
36int raw_patch_instruction(unsigned int *addr, unsigned int instr)
37{
38 return __patch_instruction(addr, instr, addr);
39}
40
41#ifdef CONFIG_STRICT_KERNEL_RWX
42static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
43
44static int text_area_cpu_up(unsigned int cpu)
45{
46 struct vm_struct *area;
47
48 area = get_vm_area(PAGE_SIZE, VM_ALLOC);
49 if (!area) {
50 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
51 cpu);
52 return -1;
53 }
54 this_cpu_write(text_poke_area, area);
55
56 return 0;
57}
58
59static int text_area_cpu_down(unsigned int cpu)
60{
61 free_vm_area(this_cpu_read(text_poke_area));
62 return 0;
63}
64
65/*
66 * Run as a late init call. This allows all the boot time patching to be done
67 * simply by patching the code, and then we're called here prior to
68 * mark_rodata_ro(), which happens after all init calls are run. Although
69 * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
70 * it as being preferable to a kernel that will crash later when someone tries
71 * to use patch_instruction().
72 */
73static int __init setup_text_poke_area(void)
74{
75 BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
76 "powerpc/text_poke:online", text_area_cpu_up,
77 text_area_cpu_down));
78
79 return 0;
80}
81late_initcall(setup_text_poke_area);
82
83/*
84 * This can be called for kernel text or a module.
85 */
86static int map_patch_area(void *addr, unsigned long text_poke_addr)
87{
88 unsigned long pfn;
89 int err;
90
91 if (is_vmalloc_addr(addr))
92 pfn = vmalloc_to_pfn(addr);
93 else
94 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
95
96 err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
97
98 pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
99 if (err)
100 return -1;
101
102 return 0;
103}
104
105static inline int unmap_patch_area(unsigned long addr)
106{
107 pte_t *ptep;
108 pmd_t *pmdp;
109 pud_t *pudp;
110 pgd_t *pgdp;
111
112 pgdp = pgd_offset_k(addr);
113 if (unlikely(!pgdp))
114 return -EINVAL;
115
116 pudp = pud_offset(pgdp, addr);
117 if (unlikely(!pudp))
118 return -EINVAL;
119
120 pmdp = pmd_offset(pudp, addr);
121 if (unlikely(!pmdp))
122 return -EINVAL;
123
124 ptep = pte_offset_kernel(pmdp, addr);
125 if (unlikely(!ptep))
126 return -EINVAL;
127
128 pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
129
130 /*
131 * In hash, pte_clear flushes the tlb, in radix, we have to
132 */
133 pte_clear(&init_mm, addr, ptep);
134 flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
135
136 return 0;
137}
138
139static int do_patch_instruction(unsigned int *addr, unsigned int instr)
140{
141 int err;
142 unsigned int *patch_addr = NULL;
143 unsigned long flags;
144 unsigned long text_poke_addr;
145 unsigned long kaddr = (unsigned long)addr;
146
147 /*
148 * During early early boot patch_instruction is called
149 * when text_poke_area is not ready, but we still need
150 * to allow patching. We just do the plain old patching
151 */
152 if (!this_cpu_read(text_poke_area))
153 return raw_patch_instruction(addr, instr);
154
155 local_irq_save(flags);
156
157 text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
158 if (map_patch_area(addr, text_poke_addr)) {
159 err = -1;
160 goto out;
161 }
162
163 patch_addr = (unsigned int *)(text_poke_addr) +
164 ((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
165
166 __patch_instruction(addr, instr, patch_addr);
167
168 err = unmap_patch_area(text_poke_addr);
169 if (err)
170 pr_warn("failed to unmap %lx\n", text_poke_addr);
171
172out:
173 local_irq_restore(flags);
174
175 return err;
176}
177#else /* !CONFIG_STRICT_KERNEL_RWX */
178
179static int do_patch_instruction(unsigned int *addr, unsigned int instr)
180{
181 return raw_patch_instruction(addr, instr);
182}
183
184#endif /* CONFIG_STRICT_KERNEL_RWX */
185
186int patch_instruction(unsigned int *addr, unsigned int instr)
187{
188 /* Make sure we aren't patching a freed init section */
189 if (init_mem_is_free && init_section_contains(addr, 4)) {
190 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
191 return 0;
192 }
193 return do_patch_instruction(addr, instr);
194}
195NOKPROBE_SYMBOL(patch_instruction);
196
197int patch_branch(unsigned int *addr, unsigned long target, int flags)
198{
199 return patch_instruction(addr, create_branch(addr, target, flags));
200}
201
202bool is_offset_in_branch_range(long offset)
203{
204 /*
205 * Powerpc branch instruction is :
206 *
207 * 0 6 30 31
208 * +---------+----------------+---+---+
209 * | opcode | LI |AA |LK |
210 * +---------+----------------+---+---+
211 * Where AA = 0 and LK = 0
212 *
213 * LI is a signed 24 bits integer. The real branch offset is computed
214 * by: imm32 = SignExtend(LI:'0b00', 32);
215 *
216 * So the maximum forward branch should be:
217 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc
218 * The maximum backward branch should be:
219 * (0xff800000 << 2) = 0xfe000000 = -0x2000000
220 */
221 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
222}
223
224/*
225 * Helper to check if a given instruction is a conditional branch
226 * Derived from the conditional checks in analyse_instr()
227 */
228bool is_conditional_branch(unsigned int instr)
229{
230 unsigned int opcode = instr >> 26;
231
232 if (opcode == 16) /* bc, bca, bcl, bcla */
233 return true;
234 if (opcode == 19) {
235 switch ((instr >> 1) & 0x3ff) {
236 case 16: /* bclr, bclrl */
237 case 528: /* bcctr, bcctrl */
238 case 560: /* bctar, bctarl */
239 return true;
240 }
241 }
242 return false;
243}
244NOKPROBE_SYMBOL(is_conditional_branch);
245
246unsigned int create_branch(const unsigned int *addr,
247 unsigned long target, int flags)
248{
249 unsigned int instruction;
250 long offset;
251
252 offset = target;
253 if (! (flags & BRANCH_ABSOLUTE))
254 offset = offset - (unsigned long)addr;
255
256 /* Check we can represent the target in the instruction format */
257 if (!is_offset_in_branch_range(offset))
258 return 0;
259
260 /* Mask out the flags and target, so they don't step on each other. */
261 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
262
263 return instruction;
264}
265
266unsigned int create_cond_branch(const unsigned int *addr,
267 unsigned long target, int flags)
268{
269 unsigned int instruction;
270 long offset;
271
272 offset = target;
273 if (! (flags & BRANCH_ABSOLUTE))
274 offset = offset - (unsigned long)addr;
275
276 /* Check we can represent the target in the instruction format */
277 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
278 return 0;
279
280 /* Mask out the flags and target, so they don't step on each other. */
281 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
282
283 return instruction;
284}
285
286static unsigned int branch_opcode(unsigned int instr)
287{
288 return (instr >> 26) & 0x3F;
289}
290
291static int instr_is_branch_iform(unsigned int instr)
292{
293 return branch_opcode(instr) == 18;
294}
295
296static int instr_is_branch_bform(unsigned int instr)
297{
298 return branch_opcode(instr) == 16;
299}
300
301int instr_is_relative_branch(unsigned int instr)
302{
303 if (instr & BRANCH_ABSOLUTE)
304 return 0;
305
306 return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
307}
308
309int instr_is_relative_link_branch(unsigned int instr)
310{
311 return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
312}
313
314static unsigned long branch_iform_target(const unsigned int *instr)
315{
316 signed long imm;
317
318 imm = *instr & 0x3FFFFFC;
319
320 /* If the top bit of the immediate value is set this is negative */
321 if (imm & 0x2000000)
322 imm -= 0x4000000;
323
324 if ((*instr & BRANCH_ABSOLUTE) == 0)
325 imm += (unsigned long)instr;
326
327 return (unsigned long)imm;
328}
329
330static unsigned long branch_bform_target(const unsigned int *instr)
331{
332 signed long imm;
333
334 imm = *instr & 0xFFFC;
335
336 /* If the top bit of the immediate value is set this is negative */
337 if (imm & 0x8000)
338 imm -= 0x10000;
339
340 if ((*instr & BRANCH_ABSOLUTE) == 0)
341 imm += (unsigned long)instr;
342
343 return (unsigned long)imm;
344}
345
346unsigned long branch_target(const unsigned int *instr)
347{
348 if (instr_is_branch_iform(*instr))
349 return branch_iform_target(instr);
350 else if (instr_is_branch_bform(*instr))
351 return branch_bform_target(instr);
352
353 return 0;
354}
355
356int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
357{
358 if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
359 return branch_target(instr) == addr;
360
361 return 0;
362}
363
364unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
365{
366 unsigned long target;
367
368 target = branch_target(src);
369
370 if (instr_is_branch_iform(*src))
371 return create_branch(dest, target, *src);
372 else if (instr_is_branch_bform(*src))
373 return create_cond_branch(dest, target, *src);
374
375 return 0;
376}
377
378#ifdef CONFIG_PPC_BOOK3E_64
379void __patch_exception(int exc, unsigned long addr)
380{
381 extern unsigned int interrupt_base_book3e;
382 unsigned int *ibase = &interrupt_base_book3e;
383
384 /* Our exceptions vectors start with a NOP and -then- a branch
385 * to deal with single stepping from userspace which stops on
386 * the second instruction. Thus we need to patch the second
387 * instruction of the exception, not the first one
388 */
389
390 patch_branch(ibase + (exc / 4) + 1, addr, 0);
391}
392#endif
393
394#ifdef CONFIG_CODE_PATCHING_SELFTEST
395
396static void __init test_trampoline(void)
397{
398 asm ("nop;\n");
399}
400
401#define check(x) \
402 if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
403
404static void __init test_branch_iform(void)
405{
406 unsigned int instr;
407 unsigned long addr;
408
409 addr = (unsigned long)&instr;
410
411 /* The simplest case, branch to self, no flags */
412 check(instr_is_branch_iform(0x48000000));
413 /* All bits of target set, and flags */
414 check(instr_is_branch_iform(0x4bffffff));
415 /* High bit of opcode set, which is wrong */
416 check(!instr_is_branch_iform(0xcbffffff));
417 /* Middle bits of opcode set, which is wrong */
418 check(!instr_is_branch_iform(0x7bffffff));
419
420 /* Simplest case, branch to self with link */
421 check(instr_is_branch_iform(0x48000001));
422 /* All bits of targets set */
423 check(instr_is_branch_iform(0x4bfffffd));
424 /* Some bits of targets set */
425 check(instr_is_branch_iform(0x4bff00fd));
426 /* Must be a valid branch to start with */
427 check(!instr_is_branch_iform(0x7bfffffd));
428
429 /* Absolute branch to 0x100 */
430 instr = 0x48000103;
431 check(instr_is_branch_to_addr(&instr, 0x100));
432 /* Absolute branch to 0x420fc */
433 instr = 0x480420ff;
434 check(instr_is_branch_to_addr(&instr, 0x420fc));
435 /* Maximum positive relative branch, + 20MB - 4B */
436 instr = 0x49fffffc;
437 check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
438 /* Smallest negative relative branch, - 4B */
439 instr = 0x4bfffffc;
440 check(instr_is_branch_to_addr(&instr, addr - 4));
441 /* Largest negative relative branch, - 32 MB */
442 instr = 0x4a000000;
443 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
444
445 /* Branch to self, with link */
446 instr = create_branch(&instr, addr, BRANCH_SET_LINK);
447 check(instr_is_branch_to_addr(&instr, addr));
448
449 /* Branch to self - 0x100, with link */
450 instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
451 check(instr_is_branch_to_addr(&instr, addr - 0x100));
452
453 /* Branch to self + 0x100, no link */
454 instr = create_branch(&instr, addr + 0x100, 0);
455 check(instr_is_branch_to_addr(&instr, addr + 0x100));
456
457 /* Maximum relative negative offset, - 32 MB */
458 instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
459 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
460
461 /* Out of range relative negative offset, - 32 MB + 4*/
462 instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
463 check(instr == 0);
464
465 /* Out of range relative positive offset, + 32 MB */
466 instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
467 check(instr == 0);
468
469 /* Unaligned target */
470 instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
471 check(instr == 0);
472
473 /* Check flags are masked correctly */
474 instr = create_branch(&instr, addr, 0xFFFFFFFC);
475 check(instr_is_branch_to_addr(&instr, addr));
476 check(instr == 0x48000000);
477}
478
479static void __init test_create_function_call(void)
480{
481 unsigned int *iptr;
482 unsigned long dest;
483
484 /* Check we can create a function call */
485 iptr = (unsigned int *)ppc_function_entry(test_trampoline);
486 dest = ppc_function_entry(test_create_function_call);
487 patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
488 check(instr_is_branch_to_addr(iptr, dest));
489}
490
491static void __init test_branch_bform(void)
492{
493 unsigned long addr;
494 unsigned int *iptr, instr, flags;
495
496 iptr = &instr;
497 addr = (unsigned long)iptr;
498
499 /* The simplest case, branch to self, no flags */
500 check(instr_is_branch_bform(0x40000000));
501 /* All bits of target set, and flags */
502 check(instr_is_branch_bform(0x43ffffff));
503 /* High bit of opcode set, which is wrong */
504 check(!instr_is_branch_bform(0xc3ffffff));
505 /* Middle bits of opcode set, which is wrong */
506 check(!instr_is_branch_bform(0x7bffffff));
507
508 /* Absolute conditional branch to 0x100 */
509 instr = 0x43ff0103;
510 check(instr_is_branch_to_addr(&instr, 0x100));
511 /* Absolute conditional branch to 0x20fc */
512 instr = 0x43ff20ff;
513 check(instr_is_branch_to_addr(&instr, 0x20fc));
514 /* Maximum positive relative conditional branch, + 32 KB - 4B */
515 instr = 0x43ff7ffc;
516 check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
517 /* Smallest negative relative conditional branch, - 4B */
518 instr = 0x43fffffc;
519 check(instr_is_branch_to_addr(&instr, addr - 4));
520 /* Largest negative relative conditional branch, - 32 KB */
521 instr = 0x43ff8000;
522 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
523
524 /* All condition code bits set & link */
525 flags = 0x3ff000 | BRANCH_SET_LINK;
526
527 /* Branch to self */
528 instr = create_cond_branch(iptr, addr, flags);
529 check(instr_is_branch_to_addr(&instr, addr));
530
531 /* Branch to self - 0x100 */
532 instr = create_cond_branch(iptr, addr - 0x100, flags);
533 check(instr_is_branch_to_addr(&instr, addr - 0x100));
534
535 /* Branch to self + 0x100 */
536 instr = create_cond_branch(iptr, addr + 0x100, flags);
537 check(instr_is_branch_to_addr(&instr, addr + 0x100));
538
539 /* Maximum relative negative offset, - 32 KB */
540 instr = create_cond_branch(iptr, addr - 0x8000, flags);
541 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
542
543 /* Out of range relative negative offset, - 32 KB + 4*/
544 instr = create_cond_branch(iptr, addr - 0x8004, flags);
545 check(instr == 0);
546
547 /* Out of range relative positive offset, + 32 KB */
548 instr = create_cond_branch(iptr, addr + 0x8000, flags);
549 check(instr == 0);
550
551 /* Unaligned target */
552 instr = create_cond_branch(iptr, addr + 3, flags);
553 check(instr == 0);
554
555 /* Check flags are masked correctly */
556 instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
557 check(instr_is_branch_to_addr(&instr, addr));
558 check(instr == 0x43FF0000);
559}
560
561static void __init test_translate_branch(void)
562{
563 unsigned long addr;
564 unsigned int *p, *q;
565 void *buf;
566
567 buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
568 check(buf);
569 if (!buf)
570 return;
571
572 /* Simple case, branch to self moved a little */
573 p = buf;
574 addr = (unsigned long)p;
575 patch_branch(p, addr, 0);
576 check(instr_is_branch_to_addr(p, addr));
577 q = p + 1;
578 patch_instruction(q, translate_branch(q, p));
579 check(instr_is_branch_to_addr(q, addr));
580
581 /* Maximum negative case, move b . to addr + 32 MB */
582 p = buf;
583 addr = (unsigned long)p;
584 patch_branch(p, addr, 0);
585 q = buf + 0x2000000;
586 patch_instruction(q, translate_branch(q, p));
587 check(instr_is_branch_to_addr(p, addr));
588 check(instr_is_branch_to_addr(q, addr));
589 check(*q == 0x4a000000);
590
591 /* Maximum positive case, move x to x - 32 MB + 4 */
592 p = buf + 0x2000000;
593 addr = (unsigned long)p;
594 patch_branch(p, addr, 0);
595 q = buf + 4;
596 patch_instruction(q, translate_branch(q, p));
597 check(instr_is_branch_to_addr(p, addr));
598 check(instr_is_branch_to_addr(q, addr));
599 check(*q == 0x49fffffc);
600
601 /* Jump to x + 16 MB moved to x + 20 MB */
602 p = buf;
603 addr = 0x1000000 + (unsigned long)buf;
604 patch_branch(p, addr, BRANCH_SET_LINK);
605 q = buf + 0x1400000;
606 patch_instruction(q, translate_branch(q, p));
607 check(instr_is_branch_to_addr(p, addr));
608 check(instr_is_branch_to_addr(q, addr));
609
610 /* Jump to x + 16 MB moved to x - 16 MB + 4 */
611 p = buf + 0x1000000;
612 addr = 0x2000000 + (unsigned long)buf;
613 patch_branch(p, addr, 0);
614 q = buf + 4;
615 patch_instruction(q, translate_branch(q, p));
616 check(instr_is_branch_to_addr(p, addr));
617 check(instr_is_branch_to_addr(q, addr));
618
619
620 /* Conditional branch tests */
621
622 /* Simple case, branch to self moved a little */
623 p = buf;
624 addr = (unsigned long)p;
625 patch_instruction(p, create_cond_branch(p, addr, 0));
626 check(instr_is_branch_to_addr(p, addr));
627 q = p + 1;
628 patch_instruction(q, translate_branch(q, p));
629 check(instr_is_branch_to_addr(q, addr));
630
631 /* Maximum negative case, move b . to addr + 32 KB */
632 p = buf;
633 addr = (unsigned long)p;
634 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
635 q = buf + 0x8000;
636 patch_instruction(q, translate_branch(q, p));
637 check(instr_is_branch_to_addr(p, addr));
638 check(instr_is_branch_to_addr(q, addr));
639 check(*q == 0x43ff8000);
640
641 /* Maximum positive case, move x to x - 32 KB + 4 */
642 p = buf + 0x8000;
643 addr = (unsigned long)p;
644 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
645 q = buf + 4;
646 patch_instruction(q, translate_branch(q, p));
647 check(instr_is_branch_to_addr(p, addr));
648 check(instr_is_branch_to_addr(q, addr));
649 check(*q == 0x43ff7ffc);
650
651 /* Jump to x + 12 KB moved to x + 20 KB */
652 p = buf;
653 addr = 0x3000 + (unsigned long)buf;
654 patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
655 q = buf + 0x5000;
656 patch_instruction(q, translate_branch(q, p));
657 check(instr_is_branch_to_addr(p, addr));
658 check(instr_is_branch_to_addr(q, addr));
659
660 /* Jump to x + 8 KB moved to x - 8 KB + 4 */
661 p = buf + 0x2000;
662 addr = 0x4000 + (unsigned long)buf;
663 patch_instruction(p, create_cond_branch(p, addr, 0));
664 q = buf + 4;
665 patch_instruction(q, translate_branch(q, p));
666 check(instr_is_branch_to_addr(p, addr));
667 check(instr_is_branch_to_addr(q, addr));
668
669 /* Free the buffer we were using */
670 vfree(buf);
671}
672
673static int __init test_code_patching(void)
674{
675 printk(KERN_DEBUG "Running code patching self-tests ...\n");
676
677 test_branch_iform();
678 test_branch_bform();
679 test_create_function_call();
680 test_translate_branch();
681
682 return 0;
683}
684late_initcall(test_code_patching);
685
686#endif /* CONFIG_CODE_PATCHING_SELFTEST */