arch/powerpc/lib/code-patching.c

   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
  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  * 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  */
  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  * 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_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          * 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
 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          * 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
 172 out:
 173         local_irq_restore(flags);
 174
 175         return err;
 176 }
 177 #else /* !CONFIG_STRICT_KERNEL_RWX */
 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 /* CONFIG_STRICT_KERNEL_RWX */
 185
 186 int 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 }
 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          * 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 bool is_offset_in_cond_branch_range(long offset)
 225 {
 226         return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
 227 }
 228
 229 /*
 230  * Helper to check if a given instruction is a conditional branch
 231  * Derived from the conditional checks in analyse_instr()
 232  */
 233 bool is_conditional_branch(unsigned int instr)
 234 {
 235         unsigned int opcode = instr >> 26;
 236
 237         if (opcode == 16)       /* bc, bca, bcl, bcla */
 238                 return true;
 239         if (opcode == 19) {
 240                 switch ((instr >> 1) & 0x3ff) {
 241                 case 16:        /* bclr, bclrl */
 242                 case 528:       /* bcctr, bcctrl */
 243                 case 560:       /* bctar, bctarl */
 244                         return true;
 245                 }
 246         }
 247         return false;
 248 }
 249 NOKPROBE_SYMBOL(is_conditional_branch);
 250
 251 unsigned int create_branch(const unsigned int *addr,
 252                            unsigned long target, int flags)
 253 {
 254         unsigned int instruction;
 255         long offset;
 256
 257         offset = target;
 258         if (! (flags & BRANCH_ABSOLUTE))
 259                 offset = offset - (unsigned long)addr;
 260
 261         /* Check we can represent the target in the instruction format */
 262         if (!is_offset_in_branch_range(offset))
 263                 return 0;
 264
 265         /* Mask out the flags and target, so they don't step on each other. */
 266         instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
 267
 268         return instruction;
 269 }
 270
 271 unsigned int create_cond_branch(const unsigned int *addr,
 272                                 unsigned long target, int flags)
 273 {
 274         unsigned int instruction;
 275         long offset;
 276
 277         offset = target;
 278         if (! (flags & BRANCH_ABSOLUTE))
 279                 offset = offset - (unsigned long)addr;
 280
 281         /* Check we can represent the target in the instruction format */
 282         if (!is_offset_in_cond_branch_range(offset))
 283                 return 0;
 284
 285         /* Mask out the flags and target, so they don't step on each other. */
 286         instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
 287
 288         return instruction;
 289 }
 290
 291 static unsigned int branch_opcode(unsigned int instr)
 292 {
 293         return (instr >> 26) & 0x3F;
 294 }
 295
 296 static int instr_is_branch_iform(unsigned int instr)
 297 {
 298         return branch_opcode(instr) == 18;
 299 }
 300
 301 static int instr_is_branch_bform(unsigned int instr)
 302 {
 303         return branch_opcode(instr) == 16;
 304 }
 305
 306 int instr_is_relative_branch(unsigned int instr)
 307 {
 308         if (instr & BRANCH_ABSOLUTE)
 309                 return 0;
 310
 311         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 312 }
 313
 314 int instr_is_relative_link_branch(unsigned int instr)
 315 {
 316         return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
 317 }
 318
 319 static unsigned long branch_iform_target(const unsigned int *instr)
 320 {
 321         signed long imm;
 322
 323         imm = *instr & 0x3FFFFFC;
 324
 325         /* If the top bit of the immediate value is set this is negative */
 326         if (imm & 0x2000000)
 327                 imm -= 0x4000000;
 328
 329         if ((*instr & BRANCH_ABSOLUTE) == 0)
 330                 imm += (unsigned long)instr;
 331
 332         return (unsigned long)imm;
 333 }
 334
 335 static unsigned long branch_bform_target(const unsigned int *instr)
 336 {
 337         signed long imm;
 338
 339         imm = *instr & 0xFFFC;
 340
 341         /* If the top bit of the immediate value is set this is negative */
 342         if (imm & 0x8000)
 343                 imm -= 0x10000;
 344
 345         if ((*instr & BRANCH_ABSOLUTE) == 0)
 346                 imm += (unsigned long)instr;
 347
 348         return (unsigned long)imm;
 349 }
 350
 351 unsigned long branch_target(const unsigned int *instr)
 352 {
 353         if (instr_is_branch_iform(*instr))
 354                 return branch_iform_target(instr);
 355         else if (instr_is_branch_bform(*instr))
 356                 return branch_bform_target(instr);
 357
 358         return 0;
 359 }
 360
 361 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
 362 {
 363         if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
 364                 return branch_target(instr) == addr;
 365
 366         return 0;
 367 }
 368
 369 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
 370 {
 371         unsigned long target;
 372
 373         target = branch_target(src);
 374
 375         if (instr_is_branch_iform(*src))
 376                 return create_branch(dest, target, *src);
 377         else if (instr_is_branch_bform(*src))
 378                 return create_cond_branch(dest, target, *src);
 379
 380         return 0;
 381 }
 382
 383 #ifdef CONFIG_PPC_BOOK3E_64
 384 void __patch_exception(int exc, unsigned long addr)
 385 {
 386         extern unsigned int interrupt_base_book3e;
 387         unsigned int *ibase = &interrupt_base_book3e;
 388
 389         /* Our exceptions vectors start with a NOP and -then- a branch
 390          * to deal with single stepping from userspace which stops on
 391          * the second instruction. Thus we need to patch the second
 392          * instruction of the exception, not the first one
 393          */
 394
 395         patch_branch(ibase + (exc / 4) + 1, addr, 0);
 396 }
 397 #endif
 398
 399 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 400
 401 static void __init test_trampoline(void)
 402 {
 403         asm ("nop;\n");
 404 }
 405
 406 #define check(x)        \
 407         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 408
 409 static void __init test_branch_iform(void)
 410 {
 411         unsigned int instr;
 412         unsigned long addr;
 413
 414         addr = (unsigned long)&instr;
 415
 416         /* The simplest case, branch to self, no flags */
 417         check(instr_is_branch_iform(0x48000000));
 418         /* All bits of target set, and flags */
 419         check(instr_is_branch_iform(0x4bffffff));
 420         /* High bit of opcode set, which is wrong */
 421         check(!instr_is_branch_iform(0xcbffffff));
 422         /* Middle bits of opcode set, which is wrong */
 423         check(!instr_is_branch_iform(0x7bffffff));
 424
 425         /* Simplest case, branch to self with link */
 426         check(instr_is_branch_iform(0x48000001));
 427         /* All bits of targets set */
 428         check(instr_is_branch_iform(0x4bfffffd));
 429         /* Some bits of targets set */
 430         check(instr_is_branch_iform(0x4bff00fd));
 431         /* Must be a valid branch to start with */
 432         check(!instr_is_branch_iform(0x7bfffffd));
 433
 434         /* Absolute branch to 0x100 */
 435         instr = 0x48000103;
 436         check(instr_is_branch_to_addr(&instr, 0x100));
 437         /* Absolute branch to 0x420fc */
 438         instr = 0x480420ff;
 439         check(instr_is_branch_to_addr(&instr, 0x420fc));
 440         /* Maximum positive relative branch, + 20MB - 4B */
 441         instr = 0x49fffffc;
 442         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 443         /* Smallest negative relative branch, - 4B */
 444         instr = 0x4bfffffc;
 445         check(instr_is_branch_to_addr(&instr, addr - 4));
 446         /* Largest negative relative branch, - 32 MB */
 447         instr = 0x4a000000;
 448         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 449
 450         /* Branch to self, with link */
 451         instr = create_branch(&instr, addr, BRANCH_SET_LINK);
 452         check(instr_is_branch_to_addr(&instr, addr));
 453
 454         /* Branch to self - 0x100, with link */
 455         instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
 456         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 457
 458         /* Branch to self + 0x100, no link */
 459         instr = create_branch(&instr, addr + 0x100, 0);
 460         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 461
 462         /* Maximum relative negative offset, - 32 MB */
 463         instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
 464         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 465
 466         /* Out of range relative negative offset, - 32 MB + 4*/
 467         instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
 468         check(instr == 0);
 469
 470         /* Out of range relative positive offset, + 32 MB */
 471         instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
 472         check(instr == 0);
 473
 474         /* Unaligned target */
 475         instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
 476         check(instr == 0);
 477
 478         /* Check flags are masked correctly */
 479         instr = create_branch(&instr, addr, 0xFFFFFFFC);
 480         check(instr_is_branch_to_addr(&instr, addr));
 481         check(instr == 0x48000000);
 482 }
 483
 484 static void __init test_create_function_call(void)
 485 {
 486         unsigned int *iptr;
 487         unsigned long dest;
 488
 489         /* Check we can create a function call */
 490         iptr = (unsigned int *)ppc_function_entry(test_trampoline);
 491         dest = ppc_function_entry(test_create_function_call);
 492         patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
 493         check(instr_is_branch_to_addr(iptr, dest));
 494 }
 495
 496 static void __init test_branch_bform(void)
 497 {
 498         unsigned long addr;
 499         unsigned int *iptr, instr, flags;
 500
 501         iptr = &instr;
 502         addr = (unsigned long)iptr;
 503
 504         /* The simplest case, branch to self, no flags */
 505         check(instr_is_branch_bform(0x40000000));
 506         /* All bits of target set, and flags */
 507         check(instr_is_branch_bform(0x43ffffff));
 508         /* High bit of opcode set, which is wrong */
 509         check(!instr_is_branch_bform(0xc3ffffff));
 510         /* Middle bits of opcode set, which is wrong */
 511         check(!instr_is_branch_bform(0x7bffffff));
 512
 513         /* Absolute conditional branch to 0x100 */
 514         instr = 0x43ff0103;
 515         check(instr_is_branch_to_addr(&instr, 0x100));
 516         /* Absolute conditional branch to 0x20fc */
 517         instr = 0x43ff20ff;
 518         check(instr_is_branch_to_addr(&instr, 0x20fc));
 519         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 520         instr = 0x43ff7ffc;
 521         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 522         /* Smallest negative relative conditional branch, - 4B */
 523         instr = 0x43fffffc;
 524         check(instr_is_branch_to_addr(&instr, addr - 4));
 525         /* Largest negative relative conditional branch, - 32 KB */
 526         instr = 0x43ff8000;
 527         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 528
 529         /* All condition code bits set & link */
 530         flags = 0x3ff000 | BRANCH_SET_LINK;
 531
 532         /* Branch to self */
 533         instr = create_cond_branch(iptr, addr, flags);
 534         check(instr_is_branch_to_addr(&instr, addr));
 535
 536         /* Branch to self - 0x100 */
 537         instr = create_cond_branch(iptr, addr - 0x100, flags);
 538         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 539
 540         /* Branch to self + 0x100 */
 541         instr = create_cond_branch(iptr, addr + 0x100, flags);
 542         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 543
 544         /* Maximum relative negative offset, - 32 KB */
 545         instr = create_cond_branch(iptr, addr - 0x8000, flags);
 546         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 547
 548         /* Out of range relative negative offset, - 32 KB + 4*/
 549         instr = create_cond_branch(iptr, addr - 0x8004, flags);
 550         check(instr == 0);
 551
 552         /* Out of range relative positive offset, + 32 KB */
 553         instr = create_cond_branch(iptr, addr + 0x8000, flags);
 554         check(instr == 0);
 555
 556         /* Unaligned target */
 557         instr = create_cond_branch(iptr, addr + 3, flags);
 558         check(instr == 0);
 559
 560         /* Check flags are masked correctly */
 561         instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
 562         check(instr_is_branch_to_addr(&instr, addr));
 563         check(instr == 0x43FF0000);
 564 }
 565
 566 static void __init test_translate_branch(void)
 567 {
 568         unsigned long addr;
 569         unsigned int *p, *q;
 570         void *buf;
 571
 572         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 573         check(buf);
 574         if (!buf)
 575                 return;
 576
 577         /* Simple case, branch to self moved a little */
 578         p = buf;
 579         addr = (unsigned long)p;
 580         patch_branch(p, addr, 0);
 581         check(instr_is_branch_to_addr(p, addr));
 582         q = p + 1;
 583         patch_instruction(q, translate_branch(q, p));
 584         check(instr_is_branch_to_addr(q, addr));
 585
 586         /* Maximum negative case, move b . to addr + 32 MB */
 587         p = buf;
 588         addr = (unsigned long)p;
 589         patch_branch(p, addr, 0);
 590         q = buf + 0x2000000;
 591         patch_instruction(q, translate_branch(q, p));
 592         check(instr_is_branch_to_addr(p, addr));
 593         check(instr_is_branch_to_addr(q, addr));
 594         check(*q == 0x4a000000);
 595
 596         /* Maximum positive case, move x to x - 32 MB + 4 */
 597         p = buf + 0x2000000;
 598         addr = (unsigned long)p;
 599         patch_branch(p, addr, 0);
 600         q = buf + 4;
 601         patch_instruction(q, translate_branch(q, p));
 602         check(instr_is_branch_to_addr(p, addr));
 603         check(instr_is_branch_to_addr(q, addr));
 604         check(*q == 0x49fffffc);
 605
 606         /* Jump to x + 16 MB moved to x + 20 MB */
 607         p = buf;
 608         addr = 0x1000000 + (unsigned long)buf;
 609         patch_branch(p, addr, BRANCH_SET_LINK);
 610         q = buf + 0x1400000;
 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         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 616         p = buf + 0x1000000;
 617         addr = 0x2000000 + (unsigned long)buf;
 618         patch_branch(p, addr, 0);
 619         q = buf + 4;
 620         patch_instruction(q, translate_branch(q, p));
 621         check(instr_is_branch_to_addr(p, addr));
 622         check(instr_is_branch_to_addr(q, addr));
 623
 624
 625         /* Conditional branch tests */
 626
 627         /* Simple case, branch to self moved a little */
 628         p = buf;
 629         addr = (unsigned long)p;
 630         patch_instruction(p, create_cond_branch(p, addr, 0));
 631         check(instr_is_branch_to_addr(p, addr));
 632         q = p + 1;
 633         patch_instruction(q, translate_branch(q, p));
 634         check(instr_is_branch_to_addr(q, addr));
 635
 636         /* Maximum negative case, move b . to addr + 32 KB */
 637         p = buf;
 638         addr = (unsigned long)p;
 639         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 640         q = buf + 0x8000;
 641         patch_instruction(q, translate_branch(q, p));
 642         check(instr_is_branch_to_addr(p, addr));
 643         check(instr_is_branch_to_addr(q, addr));
 644         check(*q == 0x43ff8000);
 645
 646         /* Maximum positive case, move x to x - 32 KB + 4 */
 647         p = buf + 0x8000;
 648         addr = (unsigned long)p;
 649         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 650         q = buf + 4;
 651         patch_instruction(q, translate_branch(q, p));
 652         check(instr_is_branch_to_addr(p, addr));
 653         check(instr_is_branch_to_addr(q, addr));
 654         check(*q == 0x43ff7ffc);
 655
 656         /* Jump to x + 12 KB moved to x + 20 KB */
 657         p = buf;
 658         addr = 0x3000 + (unsigned long)buf;
 659         patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
 660         q = buf + 0x5000;
 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         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 666         p = buf + 0x2000;
 667         addr = 0x4000 + (unsigned long)buf;
 668         patch_instruction(p, create_cond_branch(p, addr, 0));
 669         q = buf + 4;
 670         patch_instruction(q, translate_branch(q, p));
 671         check(instr_is_branch_to_addr(p, addr));
 672         check(instr_is_branch_to_addr(q, addr));
 673
 674         /* Free the buffer we were using */
 675         vfree(buf);
 676 }
 677
 678 static int __init test_code_patching(void)
 679 {
 680         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 681
 682         test_branch_iform();
 683         test_branch_bform();
 684         test_create_function_call();
 685         test_translate_branch();
 686
 687         return 0;
 688 }
 689 late_initcall(test_code_patching);
 690
 691 #endif /* CONFIG_CODE_PATCHING_SELFTEST */