GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / powerpc / lib / code-patching.c
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 #include <asm/sections.h>
26
27 static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
28                                unsigned int *patch_addr)
29 {
30         int err;
31
32         __put_user_size(instr, patch_addr, 4, err);
33         if (err)
34                 return err;
35
36         asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
37                                                             "r" (exec_addr));
38
39         return 0;
40 }
41
42 int raw_patch_instruction(unsigned int *addr, unsigned int instr)
43 {
44         return __patch_instruction(addr, instr, addr);
45 }
46
47 #ifdef CONFIG_STRICT_KERNEL_RWX
48 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
49
50 static int text_area_cpu_up(unsigned int cpu)
51 {
52         struct vm_struct *area;
53
54         area = get_vm_area(PAGE_SIZE, VM_ALLOC);
55         if (!area) {
56                 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
57                         cpu);
58                 return -1;
59         }
60         this_cpu_write(text_poke_area, area);
61
62         return 0;
63 }
64
65 static int text_area_cpu_down(unsigned int cpu)
66 {
67         free_vm_area(this_cpu_read(text_poke_area));
68         return 0;
69 }
70
71 /*
72  * Run as a late init call. This allows all the boot time patching to be done
73  * simply by patching the code, and then we're called here prior to
74  * mark_rodata_ro(), which happens after all init calls are run. Although
75  * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
76  * it as being preferable to a kernel that will crash later when someone tries
77  * to use patch_instruction().
78  */
79 static int __init setup_text_poke_area(void)
80 {
81         BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
82                 "powerpc/text_poke:online", text_area_cpu_up,
83                 text_area_cpu_down));
84
85         return 0;
86 }
87 late_initcall(setup_text_poke_area);
88
89 /*
90  * This can be called for kernel text or a module.
91  */
92 static int map_patch_area(void *addr, unsigned long text_poke_addr)
93 {
94         unsigned long pfn;
95         int err;
96
97         if (is_vmalloc_addr(addr))
98                 pfn = vmalloc_to_pfn(addr);
99         else
100                 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
101
102         err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT),
103                                 pgprot_val(PAGE_KERNEL));
104
105         pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
106         if (err)
107                 return -1;
108
109         return 0;
110 }
111
112 static inline int unmap_patch_area(unsigned long addr)
113 {
114         pte_t *ptep;
115         pmd_t *pmdp;
116         pud_t *pudp;
117         pgd_t *pgdp;
118
119         pgdp = pgd_offset_k(addr);
120         if (unlikely(!pgdp))
121                 return -EINVAL;
122
123         pudp = pud_offset(pgdp, addr);
124         if (unlikely(!pudp))
125                 return -EINVAL;
126
127         pmdp = pmd_offset(pudp, addr);
128         if (unlikely(!pmdp))
129                 return -EINVAL;
130
131         ptep = pte_offset_kernel(pmdp, addr);
132         if (unlikely(!ptep))
133                 return -EINVAL;
134
135         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
136
137         /*
138          * In hash, pte_clear flushes the tlb, in radix, we have to
139          */
140         pte_clear(&init_mm, addr, ptep);
141         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
142
143         return 0;
144 }
145
146 static int do_patch_instruction(unsigned int *addr, unsigned int instr)
147 {
148         int err;
149         unsigned int *patch_addr = NULL;
150         unsigned long flags;
151         unsigned long text_poke_addr;
152         unsigned long kaddr = (unsigned long)addr;
153
154         /*
155          * During early early boot patch_instruction is called
156          * when text_poke_area is not ready, but we still need
157          * to allow patching. We just do the plain old patching
158          */
159         if (!this_cpu_read(text_poke_area))
160                 return raw_patch_instruction(addr, instr);
161
162         local_irq_save(flags);
163
164         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
165         if (map_patch_area(addr, text_poke_addr)) {
166                 err = -1;
167                 goto out;
168         }
169
170         patch_addr = (unsigned int *)(text_poke_addr) +
171                         ((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
172
173         __patch_instruction(addr, instr, patch_addr);
174
175         err = unmap_patch_area(text_poke_addr);
176         if (err)
177                 pr_warn("failed to unmap %lx\n", text_poke_addr);
178
179 out:
180         local_irq_restore(flags);
181
182         return err;
183 }
184 #else /* !CONFIG_STRICT_KERNEL_RWX */
185
186 static int do_patch_instruction(unsigned int *addr, unsigned int instr)
187 {
188         return raw_patch_instruction(addr, instr);
189 }
190
191 #endif /* CONFIG_STRICT_KERNEL_RWX */
192
193 int patch_instruction(unsigned int *addr, unsigned int instr)
194 {
195         /* Make sure we aren't patching a freed init section */
196         if (init_mem_is_free && init_section_contains(addr, 4)) {
197                 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
198                 return 0;
199         }
200         return do_patch_instruction(addr, instr);
201 }
202 NOKPROBE_SYMBOL(patch_instruction);
203
204 int patch_branch(unsigned int *addr, unsigned long target, int flags)
205 {
206         return patch_instruction(addr, create_branch(addr, target, flags));
207 }
208
209 int patch_branch_site(s32 *site, unsigned long target, int flags)
210 {
211         unsigned int *addr;
212
213         addr = (unsigned int *)((unsigned long)site + *site);
214         return patch_instruction(addr, create_branch(addr, target, flags));
215 }
216
217 int patch_instruction_site(s32 *site, unsigned int instr)
218 {
219         unsigned int *addr;
220
221         addr = (unsigned int *)((unsigned long)site + *site);
222         return patch_instruction(addr, instr);
223 }
224
225 bool is_offset_in_branch_range(long offset)
226 {
227         /*
228          * Powerpc branch instruction is :
229          *
230          *  0         6                 30   31
231          *  +---------+----------------+---+---+
232          *  | opcode  |     LI         |AA |LK |
233          *  +---------+----------------+---+---+
234          *  Where AA = 0 and LK = 0
235          *
236          * LI is a signed 24 bits integer. The real branch offset is computed
237          * by: imm32 = SignExtend(LI:'0b00', 32);
238          *
239          * So the maximum forward branch should be:
240          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
241          * The maximum backward branch should be:
242          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
243          */
244         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
245 }
246
247 bool is_offset_in_cond_branch_range(long offset)
248 {
249         return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
250 }
251
252 /*
253  * Helper to check if a given instruction is a conditional branch
254  * Derived from the conditional checks in analyse_instr()
255  */
256 bool is_conditional_branch(unsigned int instr)
257 {
258         unsigned int opcode = instr >> 26;
259
260         if (opcode == 16)       /* bc, bca, bcl, bcla */
261                 return true;
262         if (opcode == 19) {
263                 switch ((instr >> 1) & 0x3ff) {
264                 case 16:        /* bclr, bclrl */
265                 case 528:       /* bcctr, bcctrl */
266                 case 560:       /* bctar, bctarl */
267                         return true;
268                 }
269         }
270         return false;
271 }
272 NOKPROBE_SYMBOL(is_conditional_branch);
273
274 unsigned int create_branch(const unsigned int *addr,
275                            unsigned long target, int flags)
276 {
277         unsigned int instruction;
278         long offset;
279
280         offset = target;
281         if (! (flags & BRANCH_ABSOLUTE))
282                 offset = offset - (unsigned long)addr;
283
284         /* Check we can represent the target in the instruction format */
285         if (!is_offset_in_branch_range(offset))
286                 return 0;
287
288         /* Mask out the flags and target, so they don't step on each other. */
289         instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
290
291         return instruction;
292 }
293
294 unsigned int create_cond_branch(const unsigned int *addr,
295                                 unsigned long target, int flags)
296 {
297         unsigned int instruction;
298         long offset;
299
300         offset = target;
301         if (! (flags & BRANCH_ABSOLUTE))
302                 offset = offset - (unsigned long)addr;
303
304         /* Check we can represent the target in the instruction format */
305         if (!is_offset_in_cond_branch_range(offset))
306                 return 0;
307
308         /* Mask out the flags and target, so they don't step on each other. */
309         instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
310
311         return instruction;
312 }
313
314 static unsigned int branch_opcode(unsigned int instr)
315 {
316         return (instr >> 26) & 0x3F;
317 }
318
319 static int instr_is_branch_iform(unsigned int instr)
320 {
321         return branch_opcode(instr) == 18;
322 }
323
324 static int instr_is_branch_bform(unsigned int instr)
325 {
326         return branch_opcode(instr) == 16;
327 }
328
329 int instr_is_relative_branch(unsigned int instr)
330 {
331         if (instr & BRANCH_ABSOLUTE)
332                 return 0;
333
334         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
335 }
336
337 int instr_is_relative_link_branch(unsigned int instr)
338 {
339         return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
340 }
341
342 static unsigned long branch_iform_target(const unsigned int *instr)
343 {
344         signed long imm;
345
346         imm = *instr & 0x3FFFFFC;
347
348         /* If the top bit of the immediate value is set this is negative */
349         if (imm & 0x2000000)
350                 imm -= 0x4000000;
351
352         if ((*instr & BRANCH_ABSOLUTE) == 0)
353                 imm += (unsigned long)instr;
354
355         return (unsigned long)imm;
356 }
357
358 static unsigned long branch_bform_target(const unsigned int *instr)
359 {
360         signed long imm;
361
362         imm = *instr & 0xFFFC;
363
364         /* If the top bit of the immediate value is set this is negative */
365         if (imm & 0x8000)
366                 imm -= 0x10000;
367
368         if ((*instr & BRANCH_ABSOLUTE) == 0)
369                 imm += (unsigned long)instr;
370
371         return (unsigned long)imm;
372 }
373
374 unsigned long branch_target(const unsigned int *instr)
375 {
376         if (instr_is_branch_iform(*instr))
377                 return branch_iform_target(instr);
378         else if (instr_is_branch_bform(*instr))
379                 return branch_bform_target(instr);
380
381         return 0;
382 }
383
384 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
385 {
386         if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
387                 return branch_target(instr) == addr;
388
389         return 0;
390 }
391
392 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
393 {
394         unsigned long target;
395
396         target = branch_target(src);
397
398         if (instr_is_branch_iform(*src))
399                 return create_branch(dest, target, *src);
400         else if (instr_is_branch_bform(*src))
401                 return create_cond_branch(dest, target, *src);
402
403         return 0;
404 }
405
406 #ifdef CONFIG_PPC_BOOK3E_64
407 void __patch_exception(int exc, unsigned long addr)
408 {
409         extern unsigned int interrupt_base_book3e;
410         unsigned int *ibase = &interrupt_base_book3e;
411
412         /* Our exceptions vectors start with a NOP and -then- a branch
413          * to deal with single stepping from userspace which stops on
414          * the second instruction. Thus we need to patch the second
415          * instruction of the exception, not the first one
416          */
417
418         patch_branch(ibase + (exc / 4) + 1, addr, 0);
419 }
420 #endif
421
422 #ifdef CONFIG_CODE_PATCHING_SELFTEST
423
424 static void __init test_trampoline(void)
425 {
426         asm ("nop;\n");
427 }
428
429 #define check(x)        \
430         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
431
432 static void __init test_branch_iform(void)
433 {
434         unsigned int instr;
435         unsigned long addr;
436
437         addr = (unsigned long)&instr;
438
439         /* The simplest case, branch to self, no flags */
440         check(instr_is_branch_iform(0x48000000));
441         /* All bits of target set, and flags */
442         check(instr_is_branch_iform(0x4bffffff));
443         /* High bit of opcode set, which is wrong */
444         check(!instr_is_branch_iform(0xcbffffff));
445         /* Middle bits of opcode set, which is wrong */
446         check(!instr_is_branch_iform(0x7bffffff));
447
448         /* Simplest case, branch to self with link */
449         check(instr_is_branch_iform(0x48000001));
450         /* All bits of targets set */
451         check(instr_is_branch_iform(0x4bfffffd));
452         /* Some bits of targets set */
453         check(instr_is_branch_iform(0x4bff00fd));
454         /* Must be a valid branch to start with */
455         check(!instr_is_branch_iform(0x7bfffffd));
456
457         /* Absolute branch to 0x100 */
458         instr = 0x48000103;
459         check(instr_is_branch_to_addr(&instr, 0x100));
460         /* Absolute branch to 0x420fc */
461         instr = 0x480420ff;
462         check(instr_is_branch_to_addr(&instr, 0x420fc));
463         /* Maximum positive relative branch, + 20MB - 4B */
464         instr = 0x49fffffc;
465         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
466         /* Smallest negative relative branch, - 4B */
467         instr = 0x4bfffffc;
468         check(instr_is_branch_to_addr(&instr, addr - 4));
469         /* Largest negative relative branch, - 32 MB */
470         instr = 0x4a000000;
471         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
472
473         /* Branch to self, with link */
474         instr = create_branch(&instr, addr, BRANCH_SET_LINK);
475         check(instr_is_branch_to_addr(&instr, addr));
476
477         /* Branch to self - 0x100, with link */
478         instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
479         check(instr_is_branch_to_addr(&instr, addr - 0x100));
480
481         /* Branch to self + 0x100, no link */
482         instr = create_branch(&instr, addr + 0x100, 0);
483         check(instr_is_branch_to_addr(&instr, addr + 0x100));
484
485         /* Maximum relative negative offset, - 32 MB */
486         instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
487         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
488
489         /* Out of range relative negative offset, - 32 MB + 4*/
490         instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
491         check(instr == 0);
492
493         /* Out of range relative positive offset, + 32 MB */
494         instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
495         check(instr == 0);
496
497         /* Unaligned target */
498         instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
499         check(instr == 0);
500
501         /* Check flags are masked correctly */
502         instr = create_branch(&instr, addr, 0xFFFFFFFC);
503         check(instr_is_branch_to_addr(&instr, addr));
504         check(instr == 0x48000000);
505 }
506
507 static void __init test_create_function_call(void)
508 {
509         unsigned int *iptr;
510         unsigned long dest;
511
512         /* Check we can create a function call */
513         iptr = (unsigned int *)ppc_function_entry(test_trampoline);
514         dest = ppc_function_entry(test_create_function_call);
515         patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
516         check(instr_is_branch_to_addr(iptr, dest));
517 }
518
519 static void __init test_branch_bform(void)
520 {
521         unsigned long addr;
522         unsigned int *iptr, instr, flags;
523
524         iptr = &instr;
525         addr = (unsigned long)iptr;
526
527         /* The simplest case, branch to self, no flags */
528         check(instr_is_branch_bform(0x40000000));
529         /* All bits of target set, and flags */
530         check(instr_is_branch_bform(0x43ffffff));
531         /* High bit of opcode set, which is wrong */
532         check(!instr_is_branch_bform(0xc3ffffff));
533         /* Middle bits of opcode set, which is wrong */
534         check(!instr_is_branch_bform(0x7bffffff));
535
536         /* Absolute conditional branch to 0x100 */
537         instr = 0x43ff0103;
538         check(instr_is_branch_to_addr(&instr, 0x100));
539         /* Absolute conditional branch to 0x20fc */
540         instr = 0x43ff20ff;
541         check(instr_is_branch_to_addr(&instr, 0x20fc));
542         /* Maximum positive relative conditional branch, + 32 KB - 4B */
543         instr = 0x43ff7ffc;
544         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
545         /* Smallest negative relative conditional branch, - 4B */
546         instr = 0x43fffffc;
547         check(instr_is_branch_to_addr(&instr, addr - 4));
548         /* Largest negative relative conditional branch, - 32 KB */
549         instr = 0x43ff8000;
550         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
551
552         /* All condition code bits set & link */
553         flags = 0x3ff000 | BRANCH_SET_LINK;
554
555         /* Branch to self */
556         instr = create_cond_branch(iptr, addr, flags);
557         check(instr_is_branch_to_addr(&instr, addr));
558
559         /* Branch to self - 0x100 */
560         instr = create_cond_branch(iptr, addr - 0x100, flags);
561         check(instr_is_branch_to_addr(&instr, addr - 0x100));
562
563         /* Branch to self + 0x100 */
564         instr = create_cond_branch(iptr, addr + 0x100, flags);
565         check(instr_is_branch_to_addr(&instr, addr + 0x100));
566
567         /* Maximum relative negative offset, - 32 KB */
568         instr = create_cond_branch(iptr, addr - 0x8000, flags);
569         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
570
571         /* Out of range relative negative offset, - 32 KB + 4*/
572         instr = create_cond_branch(iptr, addr - 0x8004, flags);
573         check(instr == 0);
574
575         /* Out of range relative positive offset, + 32 KB */
576         instr = create_cond_branch(iptr, addr + 0x8000, flags);
577         check(instr == 0);
578
579         /* Unaligned target */
580         instr = create_cond_branch(iptr, addr + 3, flags);
581         check(instr == 0);
582
583         /* Check flags are masked correctly */
584         instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
585         check(instr_is_branch_to_addr(&instr, addr));
586         check(instr == 0x43FF0000);
587 }
588
589 static void __init test_translate_branch(void)
590 {
591         unsigned long addr;
592         unsigned int *p, *q;
593         void *buf;
594
595         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
596         check(buf);
597         if (!buf)
598                 return;
599
600         /* Simple case, branch to self moved a little */
601         p = buf;
602         addr = (unsigned long)p;
603         patch_branch(p, addr, 0);
604         check(instr_is_branch_to_addr(p, addr));
605         q = p + 1;
606         patch_instruction(q, translate_branch(q, p));
607         check(instr_is_branch_to_addr(q, addr));
608
609         /* Maximum negative case, move b . to addr + 32 MB */
610         p = buf;
611         addr = (unsigned long)p;
612         patch_branch(p, addr, 0);
613         q = buf + 0x2000000;
614         patch_instruction(q, translate_branch(q, p));
615         check(instr_is_branch_to_addr(p, addr));
616         check(instr_is_branch_to_addr(q, addr));
617         check(*q == 0x4a000000);
618
619         /* Maximum positive case, move x to x - 32 MB + 4 */
620         p = buf + 0x2000000;
621         addr = (unsigned long)p;
622         patch_branch(p, addr, 0);
623         q = buf + 4;
624         patch_instruction(q, translate_branch(q, p));
625         check(instr_is_branch_to_addr(p, addr));
626         check(instr_is_branch_to_addr(q, addr));
627         check(*q == 0x49fffffc);
628
629         /* Jump to x + 16 MB moved to x + 20 MB */
630         p = buf;
631         addr = 0x1000000 + (unsigned long)buf;
632         patch_branch(p, addr, BRANCH_SET_LINK);
633         q = buf + 0x1400000;
634         patch_instruction(q, translate_branch(q, p));
635         check(instr_is_branch_to_addr(p, addr));
636         check(instr_is_branch_to_addr(q, addr));
637
638         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
639         p = buf + 0x1000000;
640         addr = 0x2000000 + (unsigned long)buf;
641         patch_branch(p, addr, 0);
642         q = buf + 4;
643         patch_instruction(q, translate_branch(q, p));
644         check(instr_is_branch_to_addr(p, addr));
645         check(instr_is_branch_to_addr(q, addr));
646
647
648         /* Conditional branch tests */
649
650         /* Simple case, branch to self moved a little */
651         p = buf;
652         addr = (unsigned long)p;
653         patch_instruction(p, create_cond_branch(p, addr, 0));
654         check(instr_is_branch_to_addr(p, addr));
655         q = p + 1;
656         patch_instruction(q, translate_branch(q, p));
657         check(instr_is_branch_to_addr(q, addr));
658
659         /* Maximum negative case, move b . to addr + 32 KB */
660         p = buf;
661         addr = (unsigned long)p;
662         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
663         q = buf + 0x8000;
664         patch_instruction(q, translate_branch(q, p));
665         check(instr_is_branch_to_addr(p, addr));
666         check(instr_is_branch_to_addr(q, addr));
667         check(*q == 0x43ff8000);
668
669         /* Maximum positive case, move x to x - 32 KB + 4 */
670         p = buf + 0x8000;
671         addr = (unsigned long)p;
672         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
673         q = buf + 4;
674         patch_instruction(q, translate_branch(q, p));
675         check(instr_is_branch_to_addr(p, addr));
676         check(instr_is_branch_to_addr(q, addr));
677         check(*q == 0x43ff7ffc);
678
679         /* Jump to x + 12 KB moved to x + 20 KB */
680         p = buf;
681         addr = 0x3000 + (unsigned long)buf;
682         patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
683         q = buf + 0x5000;
684         patch_instruction(q, translate_branch(q, p));
685         check(instr_is_branch_to_addr(p, addr));
686         check(instr_is_branch_to_addr(q, addr));
687
688         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
689         p = buf + 0x2000;
690         addr = 0x4000 + (unsigned long)buf;
691         patch_instruction(p, create_cond_branch(p, addr, 0));
692         q = buf + 4;
693         patch_instruction(q, translate_branch(q, p));
694         check(instr_is_branch_to_addr(p, addr));
695         check(instr_is_branch_to_addr(q, addr));
696
697         /* Free the buffer we were using */
698         vfree(buf);
699 }
700
701 static int __init test_code_patching(void)
702 {
703         printk(KERN_DEBUG "Running code patching self-tests ...\n");
704
705         test_branch_iform();
706         test_branch_bform();
707         test_create_function_call();
708         test_translate_branch();
709
710         return 0;
711 }
712 late_initcall(test_code_patching);
713
714 #endif /* CONFIG_CODE_PATCHING_SELFTEST */