This source file includes following definitions.
- __patch_instruction
- raw_patch_instruction
- text_area_cpu_up
- text_area_cpu_down
- setup_text_poke_area
- map_patch_area
- unmap_patch_area
- do_patch_instruction
- do_patch_instruction
- patch_instruction
- patch_branch
- is_offset_in_branch_range
- is_conditional_branch
- create_branch
- create_cond_branch
- branch_opcode
- instr_is_branch_iform
- instr_is_branch_bform
- instr_is_relative_branch
- instr_is_relative_link_branch
- branch_iform_target
- branch_bform_target
- branch_target
- instr_is_branch_to_addr
- translate_branch
- __patch_exception
- test_trampoline
- test_branch_iform
- test_create_function_call
- test_branch_bform
- test_translate_branch
- test_code_patching
1
2
3
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
21 static 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
36 int 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
42 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
43
44 static 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
59 static 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
67
68
69
70
71
72
73 static 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 }
81 late_initcall(setup_text_poke_area);
82
83
84
85
86 static 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
105 static 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
132
133 pte_clear(&init_mm, addr, ptep);
134 flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
135
136 return 0;
137 }
138
139 static 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
149
150
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
172 out:
173 local_irq_restore(flags);
174
175 return err;
176 }
177 #else
178
179 static int do_patch_instruction(unsigned int *addr, unsigned int instr)
180 {
181 return raw_patch_instruction(addr, instr);
182 }
183
184 #endif
185
186 int patch_instruction(unsigned int *addr, unsigned int instr)
187 {
188
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 }
195 NOKPROBE_SYMBOL(patch_instruction);
196
197 int patch_branch(unsigned int *addr, unsigned long target, int flags)
198 {
199 return patch_instruction(addr, create_branch(addr, target, flags));
200 }
201
202 bool is_offset_in_branch_range(long offset)
203 {
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
222 }
223
224
225
226
227
228 bool is_conditional_branch(unsigned int instr)
229 {
230 unsigned int opcode = instr >> 26;
231
232 if (opcode == 16)
233 return true;
234 if (opcode == 19) {
235 switch ((instr >> 1) & 0x3ff) {
236 case 16:
237 case 528:
238 case 560:
239 return true;
240 }
241 }
242 return false;
243 }
244 NOKPROBE_SYMBOL(is_conditional_branch);
245
246 unsigned 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
257 if (!is_offset_in_branch_range(offset))
258 return 0;
259
260
261 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
262
263 return instruction;
264 }
265
266 unsigned 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
277 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
278 return 0;
279
280
281 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
282
283 return instruction;
284 }
285
286 static unsigned int branch_opcode(unsigned int instr)
287 {
288 return (instr >> 26) & 0x3F;
289 }
290
291 static int instr_is_branch_iform(unsigned int instr)
292 {
293 return branch_opcode(instr) == 18;
294 }
295
296 static int instr_is_branch_bform(unsigned int instr)
297 {
298 return branch_opcode(instr) == 16;
299 }
300
301 int 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
309 int instr_is_relative_link_branch(unsigned int instr)
310 {
311 return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
312 }
313
314 static unsigned long branch_iform_target(const unsigned int *instr)
315 {
316 signed long imm;
317
318 imm = *instr & 0x3FFFFFC;
319
320
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
330 static unsigned long branch_bform_target(const unsigned int *instr)
331 {
332 signed long imm;
333
334 imm = *instr & 0xFFFC;
335
336
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
346 unsigned 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
356 int 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
364 unsigned 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
379 void __patch_exception(int exc, unsigned long addr)
380 {
381 extern unsigned int interrupt_base_book3e;
382 unsigned int *ibase = &interrupt_base_book3e;
383
384
385
386
387
388
389
390 patch_branch(ibase + (exc / 4) + 1, addr, 0);
391 }
392 #endif
393
394 #ifdef CONFIG_CODE_PATCHING_SELFTEST
395
396 static 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
404 static void __init test_branch_iform(void)
405 {
406 unsigned int instr;
407 unsigned long addr;
408
409 addr = (unsigned long)&instr;
410
411
412 check(instr_is_branch_iform(0x48000000));
413
414 check(instr_is_branch_iform(0x4bffffff));
415
416 check(!instr_is_branch_iform(0xcbffffff));
417
418 check(!instr_is_branch_iform(0x7bffffff));
419
420
421 check(instr_is_branch_iform(0x48000001));
422
423 check(instr_is_branch_iform(0x4bfffffd));
424
425 check(instr_is_branch_iform(0x4bff00fd));
426
427 check(!instr_is_branch_iform(0x7bfffffd));
428
429
430 instr = 0x48000103;
431 check(instr_is_branch_to_addr(&instr, 0x100));
432
433 instr = 0x480420ff;
434 check(instr_is_branch_to_addr(&instr, 0x420fc));
435
436 instr = 0x49fffffc;
437 check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
438
439 instr = 0x4bfffffc;
440 check(instr_is_branch_to_addr(&instr, addr - 4));
441
442 instr = 0x4a000000;
443 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
444
445
446 instr = create_branch(&instr, addr, BRANCH_SET_LINK);
447 check(instr_is_branch_to_addr(&instr, addr));
448
449
450 instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
451 check(instr_is_branch_to_addr(&instr, addr - 0x100));
452
453
454 instr = create_branch(&instr, addr + 0x100, 0);
455 check(instr_is_branch_to_addr(&instr, addr + 0x100));
456
457
458 instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
459 check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
460
461
462 instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
463 check(instr == 0);
464
465
466 instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
467 check(instr == 0);
468
469
470 instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
471 check(instr == 0);
472
473
474 instr = create_branch(&instr, addr, 0xFFFFFFFC);
475 check(instr_is_branch_to_addr(&instr, addr));
476 check(instr == 0x48000000);
477 }
478
479 static void __init test_create_function_call(void)
480 {
481 unsigned int *iptr;
482 unsigned long dest;
483
484
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
491 static 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
500 check(instr_is_branch_bform(0x40000000));
501
502 check(instr_is_branch_bform(0x43ffffff));
503
504 check(!instr_is_branch_bform(0xc3ffffff));
505
506 check(!instr_is_branch_bform(0x7bffffff));
507
508
509 instr = 0x43ff0103;
510 check(instr_is_branch_to_addr(&instr, 0x100));
511
512 instr = 0x43ff20ff;
513 check(instr_is_branch_to_addr(&instr, 0x20fc));
514
515 instr = 0x43ff7ffc;
516 check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
517
518 instr = 0x43fffffc;
519 check(instr_is_branch_to_addr(&instr, addr - 4));
520
521 instr = 0x43ff8000;
522 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
523
524
525 flags = 0x3ff000 | BRANCH_SET_LINK;
526
527
528 instr = create_cond_branch(iptr, addr, flags);
529 check(instr_is_branch_to_addr(&instr, addr));
530
531
532 instr = create_cond_branch(iptr, addr - 0x100, flags);
533 check(instr_is_branch_to_addr(&instr, addr - 0x100));
534
535
536 instr = create_cond_branch(iptr, addr + 0x100, flags);
537 check(instr_is_branch_to_addr(&instr, addr + 0x100));
538
539
540 instr = create_cond_branch(iptr, addr - 0x8000, flags);
541 check(instr_is_branch_to_addr(&instr, addr - 0x8000));
542
543
544 instr = create_cond_branch(iptr, addr - 0x8004, flags);
545 check(instr == 0);
546
547
548 instr = create_cond_branch(iptr, addr + 0x8000, flags);
549 check(instr == 0);
550
551
552 instr = create_cond_branch(iptr, addr + 3, flags);
553 check(instr == 0);
554
555
556 instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
557 check(instr_is_branch_to_addr(&instr, addr));
558 check(instr == 0x43FF0000);
559 }
560
561 static 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
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
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
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
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
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
621
622
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
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
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
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
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
670 vfree(buf);
671 }
672
673 static 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 }
684 late_initcall(test_code_patching);
685
686 #endif