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Linux/arch/powerpc/lib/code-patching.c

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  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/tlbflush.h>
 16 #include <asm/page.h>
 17 #include <asm/code-patching.h>
 18 #include <asm/setup.h>
 19 #include <asm/inst.h>
 20 
 21 static int __patch_instruction(u32 *exec_addr, struct ppc_inst instr, u32 *patch_addr)
 22 {
 23         if (!ppc_inst_prefixed(instr)) {
 24                 u32 val = ppc_inst_val(instr);
 25 
 26                 __put_kernel_nofault(patch_addr, &val, u32, failed);
 27         } else {
 28                 u64 val = ppc_inst_as_ulong(instr);
 29 
 30                 __put_kernel_nofault(patch_addr, &val, u64, failed);
 31         }
 32 
 33         asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
 34                                                             "r" (exec_addr));
 35 
 36         return 0;
 37 
 38 failed:
 39         return -EFAULT;
 40 }
 41 
 42 int raw_patch_instruction(u32 *addr, struct ppc_inst 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  * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and
 73  * we judge it as being preferable to a kernel that will crash later when
 74  * someone tries to use patch_instruction().
 75  */
 76 void __init poking_init(void)
 77 {
 78         BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
 79                 "powerpc/text_poke:online", text_area_cpu_up,
 80                 text_area_cpu_down));
 81 }
 82 
 83 /*
 84  * This can be called for kernel text or a module.
 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_or_module_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         p4d_t *p4dp;
111         pgd_t *pgdp;
112 
113         pgdp = pgd_offset_k(addr);
114         if (unlikely(!pgdp))
115                 return -EINVAL;
116 
117         p4dp = p4d_offset(pgdp, addr);
118         if (unlikely(!p4dp))
119                 return -EINVAL;
120 
121         pudp = pud_offset(p4dp, addr);
122         if (unlikely(!pudp))
123                 return -EINVAL;
124 
125         pmdp = pmd_offset(pudp, addr);
126         if (unlikely(!pmdp))
127                 return -EINVAL;
128 
129         ptep = pte_offset_kernel(pmdp, addr);
130         if (unlikely(!ptep))
131                 return -EINVAL;
132 
133         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
134 
135         /*
136          * In hash, pte_clear flushes the tlb, in radix, we have to
137          */
138         pte_clear(&init_mm, addr, ptep);
139         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
140 
141         return 0;
142 }
143 
144 static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
145 {
146         int err;
147         u32 *patch_addr = NULL;
148         unsigned long flags;
149         unsigned long text_poke_addr;
150         unsigned long kaddr = (unsigned long)addr;
151 
152         /*
153          * During early early boot patch_instruction is called
154          * when text_poke_area is not ready, but we still need
155          * to allow patching. We just do the plain old patching
156          */
157         if (!this_cpu_read(text_poke_area))
158                 return raw_patch_instruction(addr, instr);
159 
160         local_irq_save(flags);
161 
162         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
163         if (map_patch_area(addr, text_poke_addr)) {
164                 err = -1;
165                 goto out;
166         }
167 
168         patch_addr = (u32 *)(text_poke_addr + (kaddr & ~PAGE_MASK));
169 
170         __patch_instruction(addr, instr, patch_addr);
171 
172         err = unmap_patch_area(text_poke_addr);
173         if (err)
174                 pr_warn("failed to unmap %lx\n", text_poke_addr);
175 
176 out:
177         local_irq_restore(flags);
178 
179         return err;
180 }
181 #else /* !CONFIG_STRICT_KERNEL_RWX */
182 
183 static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
184 {
185         return raw_patch_instruction(addr, instr);
186 }
187 
188 #endif /* CONFIG_STRICT_KERNEL_RWX */
189 
190 int patch_instruction(u32 *addr, struct ppc_inst instr)
191 {
192         /* Make sure we aren't patching a freed init section */
193         if (init_mem_is_free && init_section_contains(addr, 4)) {
194                 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
195                 return 0;
196         }
197         return do_patch_instruction(addr, instr);
198 }
199 NOKPROBE_SYMBOL(patch_instruction);
200 
201 int patch_branch(u32 *addr, unsigned long target, int flags)
202 {
203         struct ppc_inst instr;
204 
205         create_branch(&instr, addr, target, flags);
206         return patch_instruction(addr, instr);
207 }
208 
209 bool is_offset_in_branch_range(long offset)
210 {
211         /*
212          * Powerpc branch instruction is :
213          *
214          *  0         6                 30   31
215          *  +---------+----------------+---+---+
216          *  | opcode  |     LI         |AA |LK |
217          *  +---------+----------------+---+---+
218          *  Where AA = 0 and LK = 0
219          *
220          * LI is a signed 24 bits integer. The real branch offset is computed
221          * by: imm32 = SignExtend(LI:'0b00', 32);
222          *
223          * So the maximum forward branch should be:
224          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
225          * The maximum backward branch should be:
226          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
227          */
228         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
229 }
230 
231 bool is_offset_in_cond_branch_range(long offset)
232 {
233         return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
234 }
235 
236 /*
237  * Helper to check if a given instruction is a conditional branch
238  * Derived from the conditional checks in analyse_instr()
239  */
240 bool is_conditional_branch(struct ppc_inst instr)
241 {
242         unsigned int opcode = ppc_inst_primary_opcode(instr);
243 
244         if (opcode == 16)       /* bc, bca, bcl, bcla */
245                 return true;
246         if (opcode == 19) {
247                 switch ((ppc_inst_val(instr) >> 1) & 0x3ff) {
248                 case 16:        /* bclr, bclrl */
249                 case 528:       /* bcctr, bcctrl */
250                 case 560:       /* bctar, bctarl */
251                         return true;
252                 }
253         }
254         return false;
255 }
256 NOKPROBE_SYMBOL(is_conditional_branch);
257 
258 int create_branch(struct ppc_inst *instr, const u32 *addr,
259                   unsigned long target, int flags)
260 {
261         long offset;
262 
263         *instr = ppc_inst(0);
264         offset = target;
265         if (! (flags & BRANCH_ABSOLUTE))
266                 offset = offset - (unsigned long)addr;
267 
268         /* Check we can represent the target in the instruction format */
269         if (!is_offset_in_branch_range(offset))
270                 return 1;
271 
272         /* Mask out the flags and target, so they don't step on each other. */
273         *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
274 
275         return 0;
276 }
277 
278 int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
279                        unsigned long target, int flags)
280 {
281         long offset;
282 
283         offset = target;
284         if (! (flags & BRANCH_ABSOLUTE))
285                 offset = offset - (unsigned long)addr;
286 
287         /* Check we can represent the target in the instruction format */
288         if (!is_offset_in_cond_branch_range(offset))
289                 return 1;
290 
291         /* Mask out the flags and target, so they don't step on each other. */
292         *instr = ppc_inst(0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC));
293 
294         return 0;
295 }
296 
297 static unsigned int branch_opcode(struct ppc_inst instr)
298 {
299         return ppc_inst_primary_opcode(instr) & 0x3F;
300 }
301 
302 static int instr_is_branch_iform(struct ppc_inst instr)
303 {
304         return branch_opcode(instr) == 18;
305 }
306 
307 static int instr_is_branch_bform(struct ppc_inst instr)
308 {
309         return branch_opcode(instr) == 16;
310 }
311 
312 int instr_is_relative_branch(struct ppc_inst instr)
313 {
314         if (ppc_inst_val(instr) & BRANCH_ABSOLUTE)
315                 return 0;
316 
317         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
318 }
319 
320 int instr_is_relative_link_branch(struct ppc_inst instr)
321 {
322         return instr_is_relative_branch(instr) && (ppc_inst_val(instr) & BRANCH_SET_LINK);
323 }
324 
325 static unsigned long branch_iform_target(const u32 *instr)
326 {
327         signed long imm;
328 
329         imm = ppc_inst_val(ppc_inst_read(instr)) & 0x3FFFFFC;
330 
331         /* If the top bit of the immediate value is set this is negative */
332         if (imm & 0x2000000)
333                 imm -= 0x4000000;
334 
335         if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0)
336                 imm += (unsigned long)instr;
337 
338         return (unsigned long)imm;
339 }
340 
341 static unsigned long branch_bform_target(const u32 *instr)
342 {
343         signed long imm;
344 
345         imm = ppc_inst_val(ppc_inst_read(instr)) & 0xFFFC;
346 
347         /* If the top bit of the immediate value is set this is negative */
348         if (imm & 0x8000)
349                 imm -= 0x10000;
350 
351         if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0)
352                 imm += (unsigned long)instr;
353 
354         return (unsigned long)imm;
355 }
356 
357 unsigned long branch_target(const u32 *instr)
358 {
359         if (instr_is_branch_iform(ppc_inst_read(instr)))
360                 return branch_iform_target(instr);
361         else if (instr_is_branch_bform(ppc_inst_read(instr)))
362                 return branch_bform_target(instr);
363 
364         return 0;
365 }
366 
367 int translate_branch(struct ppc_inst *instr, const u32 *dest, const u32 *src)
368 {
369         unsigned long target;
370         target = branch_target(src);
371 
372         if (instr_is_branch_iform(ppc_inst_read(src)))
373                 return create_branch(instr, dest, target,
374                                      ppc_inst_val(ppc_inst_read(src)));
375         else if (instr_is_branch_bform(ppc_inst_read(src)))
376                 return create_cond_branch(instr, dest, target,
377                                           ppc_inst_val(ppc_inst_read(src)));
378 
379         return 1;
380 }
381 
382 #ifdef CONFIG_PPC_BOOK3E_64
383 void __patch_exception(int exc, unsigned long addr)
384 {
385         extern unsigned int interrupt_base_book3e;
386         unsigned int *ibase = &interrupt_base_book3e;
387 
388         /* Our exceptions vectors start with a NOP and -then- a branch
389          * to deal with single stepping from userspace which stops on
390          * the second instruction. Thus we need to patch the second
391          * instruction of the exception, not the first one
392          */
393 
394         patch_branch(ibase + (exc / 4) + 1, addr, 0);
395 }
396 #endif
397 
398 #ifdef CONFIG_CODE_PATCHING_SELFTEST
399 
400 static int instr_is_branch_to_addr(const u32 *instr, unsigned long addr)
401 {
402         if (instr_is_branch_iform(ppc_inst_read(instr)) ||
403             instr_is_branch_bform(ppc_inst_read(instr)))
404                 return branch_target(instr) == addr;
405 
406         return 0;
407 }
408 
409 static void __init test_trampoline(void)
410 {
411         asm ("nop;\n");
412 }
413 
414 #define check(x)        \
415         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
416 
417 static void __init test_branch_iform(void)
418 {
419         int err;
420         struct ppc_inst instr;
421         u32 tmp[2];
422         u32 *iptr = tmp;
423         unsigned long addr = (unsigned long)tmp;
424 
425         /* The simplest case, branch to self, no flags */
426         check(instr_is_branch_iform(ppc_inst(0x48000000)));
427         /* All bits of target set, and flags */
428         check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
429         /* High bit of opcode set, which is wrong */
430         check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
431         /* Middle bits of opcode set, which is wrong */
432         check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
433 
434         /* Simplest case, branch to self with link */
435         check(instr_is_branch_iform(ppc_inst(0x48000001)));
436         /* All bits of targets set */
437         check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
438         /* Some bits of targets set */
439         check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
440         /* Must be a valid branch to start with */
441         check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
442 
443         /* Absolute branch to 0x100 */
444         patch_instruction(iptr, ppc_inst(0x48000103));
445         check(instr_is_branch_to_addr(iptr, 0x100));
446         /* Absolute branch to 0x420fc */
447         patch_instruction(iptr, ppc_inst(0x480420ff));
448         check(instr_is_branch_to_addr(iptr, 0x420fc));
449         /* Maximum positive relative branch, + 20MB - 4B */
450         patch_instruction(iptr, ppc_inst(0x49fffffc));
451         check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
452         /* Smallest negative relative branch, - 4B */
453         patch_instruction(iptr, ppc_inst(0x4bfffffc));
454         check(instr_is_branch_to_addr(iptr, addr - 4));
455         /* Largest negative relative branch, - 32 MB */
456         patch_instruction(iptr, ppc_inst(0x4a000000));
457         check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
458 
459         /* Branch to self, with link */
460         err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
461         patch_instruction(iptr, instr);
462         check(instr_is_branch_to_addr(iptr, addr));
463 
464         /* Branch to self - 0x100, with link */
465         err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
466         patch_instruction(iptr, instr);
467         check(instr_is_branch_to_addr(iptr, addr - 0x100));
468 
469         /* Branch to self + 0x100, no link */
470         err = create_branch(&instr, iptr, addr + 0x100, 0);
471         patch_instruction(iptr, instr);
472         check(instr_is_branch_to_addr(iptr, addr + 0x100));
473 
474         /* Maximum relative negative offset, - 32 MB */
475         err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
476         patch_instruction(iptr, instr);
477         check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
478 
479         /* Out of range relative negative offset, - 32 MB + 4*/
480         err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
481         check(err);
482 
483         /* Out of range relative positive offset, + 32 MB */
484         err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
485         check(err);
486 
487         /* Unaligned target */
488         err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
489         check(err);
490 
491         /* Check flags are masked correctly */
492         err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
493         patch_instruction(iptr, instr);
494         check(instr_is_branch_to_addr(iptr, addr));
495         check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
496 }
497 
498 static void __init test_create_function_call(void)
499 {
500         u32 *iptr;
501         unsigned long dest;
502         struct ppc_inst instr;
503 
504         /* Check we can create a function call */
505         iptr = (u32 *)ppc_function_entry(test_trampoline);
506         dest = ppc_function_entry(test_create_function_call);
507         create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
508         patch_instruction(iptr, instr);
509         check(instr_is_branch_to_addr(iptr, dest));
510 }
511 
512 static void __init test_branch_bform(void)
513 {
514         int err;
515         unsigned long addr;
516         struct ppc_inst instr;
517         u32 tmp[2];
518         u32 *iptr = tmp;
519         unsigned int flags;
520 
521         addr = (unsigned long)iptr;
522 
523         /* The simplest case, branch to self, no flags */
524         check(instr_is_branch_bform(ppc_inst(0x40000000)));
525         /* All bits of target set, and flags */
526         check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
527         /* High bit of opcode set, which is wrong */
528         check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
529         /* Middle bits of opcode set, which is wrong */
530         check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
531 
532         /* Absolute conditional branch to 0x100 */
533         patch_instruction(iptr, ppc_inst(0x43ff0103));
534         check(instr_is_branch_to_addr(iptr, 0x100));
535         /* Absolute conditional branch to 0x20fc */
536         patch_instruction(iptr, ppc_inst(0x43ff20ff));
537         check(instr_is_branch_to_addr(iptr, 0x20fc));
538         /* Maximum positive relative conditional branch, + 32 KB - 4B */
539         patch_instruction(iptr, ppc_inst(0x43ff7ffc));
540         check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
541         /* Smallest negative relative conditional branch, - 4B */
542         patch_instruction(iptr, ppc_inst(0x43fffffc));
543         check(instr_is_branch_to_addr(iptr, addr - 4));
544         /* Largest negative relative conditional branch, - 32 KB */
545         patch_instruction(iptr, ppc_inst(0x43ff8000));
546         check(instr_is_branch_to_addr(iptr, addr - 0x8000));
547 
548         /* All condition code bits set & link */
549         flags = 0x3ff000 | BRANCH_SET_LINK;
550 
551         /* Branch to self */
552         err = create_cond_branch(&instr, iptr, addr, flags);
553         patch_instruction(iptr, instr);
554         check(instr_is_branch_to_addr(iptr, addr));
555 
556         /* Branch to self - 0x100 */
557         err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
558         patch_instruction(iptr, instr);
559         check(instr_is_branch_to_addr(iptr, addr - 0x100));
560 
561         /* Branch to self + 0x100 */
562         err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
563         patch_instruction(iptr, instr);
564         check(instr_is_branch_to_addr(iptr, addr + 0x100));
565 
566         /* Maximum relative negative offset, - 32 KB */
567         err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
568         patch_instruction(iptr, instr);
569         check(instr_is_branch_to_addr(iptr, addr - 0x8000));
570 
571         /* Out of range relative negative offset, - 32 KB + 4*/
572         err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
573         check(err);
574 
575         /* Out of range relative positive offset, + 32 KB */
576         err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
577         check(err);
578 
579         /* Unaligned target */
580         err = create_cond_branch(&instr, iptr, addr + 3, flags);
581         check(err);
582 
583         /* Check flags are masked correctly */
584         err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
585         patch_instruction(iptr, instr);
586         check(instr_is_branch_to_addr(iptr, addr));
587         check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
588 }
589 
590 static void __init test_translate_branch(void)
591 {
592         unsigned long addr;
593         void *p, *q;
594         struct ppc_inst instr;
595         void *buf;
596 
597         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
598         check(buf);
599         if (!buf)
600                 return;
601 
602         /* Simple case, branch to self moved a little */
603         p = buf;
604         addr = (unsigned long)p;
605         patch_branch(p, addr, 0);
606         check(instr_is_branch_to_addr(p, addr));
607         q = p + 4;
608         translate_branch(&instr, q, p);
609         patch_instruction(q, instr);
610         check(instr_is_branch_to_addr(q, addr));
611 
612         /* Maximum negative case, move b . to addr + 32 MB */
613         p = buf;
614         addr = (unsigned long)p;
615         patch_branch(p, addr, 0);
616         q = buf + 0x2000000;
617         translate_branch(&instr, q, p);
618         patch_instruction(q, instr);
619         check(instr_is_branch_to_addr(p, addr));
620         check(instr_is_branch_to_addr(q, addr));
621         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
622 
623         /* Maximum positive case, move x to x - 32 MB + 4 */
624         p = buf + 0x2000000;
625         addr = (unsigned long)p;
626         patch_branch(p, addr, 0);
627         q = buf + 4;
628         translate_branch(&instr, q, p);
629         patch_instruction(q, instr);
630         check(instr_is_branch_to_addr(p, addr));
631         check(instr_is_branch_to_addr(q, addr));
632         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
633 
634         /* Jump to x + 16 MB moved to x + 20 MB */
635         p = buf;
636         addr = 0x1000000 + (unsigned long)buf;
637         patch_branch(p, addr, BRANCH_SET_LINK);
638         q = buf + 0x1400000;
639         translate_branch(&instr, q, p);
640         patch_instruction(q, instr);
641         check(instr_is_branch_to_addr(p, addr));
642         check(instr_is_branch_to_addr(q, addr));
643 
644         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
645         p = buf + 0x1000000;
646         addr = 0x2000000 + (unsigned long)buf;
647         patch_branch(p, addr, 0);
648         q = buf + 4;
649         translate_branch(&instr, q, p);
650         patch_instruction(q, instr);
651         check(instr_is_branch_to_addr(p, addr));
652         check(instr_is_branch_to_addr(q, addr));
653 
654 
655         /* Conditional branch tests */
656 
657         /* Simple case, branch to self moved a little */
658         p = buf;
659         addr = (unsigned long)p;
660         create_cond_branch(&instr, p, addr, 0);
661         patch_instruction(p, instr);
662         check(instr_is_branch_to_addr(p, addr));
663         q = buf + 4;
664         translate_branch(&instr, q, p);
665         patch_instruction(q, instr);
666         check(instr_is_branch_to_addr(q, addr));
667 
668         /* Maximum negative case, move b . to addr + 32 KB */
669         p = buf;
670         addr = (unsigned long)p;
671         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
672         patch_instruction(p, instr);
673         q = buf + 0x8000;
674         translate_branch(&instr, q, p);
675         patch_instruction(q, instr);
676         check(instr_is_branch_to_addr(p, addr));
677         check(instr_is_branch_to_addr(q, addr));
678         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
679 
680         /* Maximum positive case, move x to x - 32 KB + 4 */
681         p = buf + 0x8000;
682         addr = (unsigned long)p;
683         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
684         patch_instruction(p, instr);
685         q = buf + 4;
686         translate_branch(&instr, q, p);
687         patch_instruction(q, instr);
688         check(instr_is_branch_to_addr(p, addr));
689         check(instr_is_branch_to_addr(q, addr));
690         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
691 
692         /* Jump to x + 12 KB moved to x + 20 KB */
693         p = buf;
694         addr = 0x3000 + (unsigned long)buf;
695         create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
696         patch_instruction(p, instr);
697         q = buf + 0x5000;
698         translate_branch(&instr, q, p);
699         patch_instruction(q, instr);
700         check(instr_is_branch_to_addr(p, addr));
701         check(instr_is_branch_to_addr(q, addr));
702 
703         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
704         p = buf + 0x2000;
705         addr = 0x4000 + (unsigned long)buf;
706         create_cond_branch(&instr, p, addr, 0);
707         patch_instruction(p, instr);
708         q = buf + 4;
709         translate_branch(&instr, q, p);
710         patch_instruction(q, instr);
711         check(instr_is_branch_to_addr(p, addr));
712         check(instr_is_branch_to_addr(q, addr));
713 
714         /* Free the buffer we were using */
715         vfree(buf);
716 }
717 
718 #ifdef CONFIG_PPC64
719 static void __init test_prefixed_patching(void)
720 {
721         extern unsigned int code_patching_test1[];
722         extern unsigned int code_patching_test1_expected[];
723         extern unsigned int end_code_patching_test1[];
724 
725         __patch_instruction(code_patching_test1,
726                             ppc_inst_prefix(OP_PREFIX << 26, 0x00000000),
727                             code_patching_test1);
728 
729         check(!memcmp(code_patching_test1,
730                       code_patching_test1_expected,
731                       sizeof(unsigned int) *
732                       (end_code_patching_test1 - code_patching_test1)));
733 }
734 #else
735 static inline void test_prefixed_patching(void) {}
736 #endif
737 
738 static int __init test_code_patching(void)
739 {
740         printk(KERN_DEBUG "Running code patching self-tests ...\n");
741 
742         test_branch_iform();
743         test_branch_bform();
744         test_create_function_call();
745         test_translate_branch();
746         test_prefixed_patching();
747 
748         return 0;
749 }
750 late_initcall(test_code_patching);
751 
752 #endif /* CONFIG_CODE_PATCHING_SELFTEST */
753 

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