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 /*
 248  * Helper to check if a given instruction is a conditional branch
 249  * Derived from the conditional checks in analyse_instr()
 250  */
 251 bool is_conditional_branch(unsigned int instr)
 252 {
 253         unsigned int opcode = instr >> 26;
 254
 255         if (opcode == 16)       /* bc, bca, bcl, bcla */
 256                 return true;
 257         if (opcode == 19) {
 258                 switch ((instr >> 1) & 0x3ff) {
 259                 case 16:        /* bclr, bclrl */
 260                 case 528:       /* bcctr, bcctrl */
 261                 case 560:       /* bctar, bctarl */
 262                         return true;
 263                 }
 264         }
 265         return false;
 266 }
 267 NOKPROBE_SYMBOL(is_conditional_branch);
 268
 269 unsigned int create_branch(const unsigned int *addr,
 270                            unsigned long target, int flags)
 271 {
 272         unsigned int instruction;
 273         long offset;
 274
 275         offset = target;
 276         if (! (flags & BRANCH_ABSOLUTE))
 277                 offset = offset - (unsigned long)addr;
 278
 279         /* Check we can represent the target in the instruction format */
 280         if (!is_offset_in_branch_range(offset))
 281                 return 0;
 282
 283         /* Mask out the flags and target, so they don't step on each other. */
 284         instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
 285
 286         return instruction;
 287 }
 288
 289 unsigned int create_cond_branch(const unsigned int *addr,
 290                                 unsigned long target, int flags)
 291 {
 292         unsigned int instruction;
 293         long offset;
 294
 295         offset = target;
 296         if (! (flags & BRANCH_ABSOLUTE))
 297                 offset = offset - (unsigned long)addr;
 298
 299         /* Check we can represent the target in the instruction format */
 300         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 301                 return 0;
 302
 303         /* Mask out the flags and target, so they don't step on each other. */
 304         instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
 305
 306         return instruction;
 307 }
 308
 309 static unsigned int branch_opcode(unsigned int instr)
 310 {
 311         return (instr >> 26) & 0x3F;
 312 }
 313
 314 static int instr_is_branch_iform(unsigned int instr)
 315 {
 316         return branch_opcode(instr) == 18;
 317 }
 318
 319 static int instr_is_branch_bform(unsigned int instr)
 320 {
 321         return branch_opcode(instr) == 16;
 322 }
 323
 324 int instr_is_relative_branch(unsigned int instr)
 325 {
 326         if (instr & BRANCH_ABSOLUTE)
 327                 return 0;
 328
 329         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 330 }
 331
 332 int instr_is_relative_link_branch(unsigned int instr)
 333 {
 334         return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
 335 }
 336
 337 static unsigned long branch_iform_target(const unsigned int *instr)
 338 {
 339         signed long imm;
 340
 341         imm = *instr & 0x3FFFFFC;
 342
 343         /* If the top bit of the immediate value is set this is negative */
 344         if (imm & 0x2000000)
 345                 imm -= 0x4000000;
 346
 347         if ((*instr & BRANCH_ABSOLUTE) == 0)
 348                 imm += (unsigned long)instr;
 349
 350         return (unsigned long)imm;
 351 }
 352
 353 static unsigned long branch_bform_target(const unsigned int *instr)
 354 {
 355         signed long imm;
 356
 357         imm = *instr & 0xFFFC;
 358
 359         /* If the top bit of the immediate value is set this is negative */
 360         if (imm & 0x8000)
 361                 imm -= 0x10000;
 362
 363         if ((*instr & BRANCH_ABSOLUTE) == 0)
 364                 imm += (unsigned long)instr;
 365
 366         return (unsigned long)imm;
 367 }
 368
 369 unsigned long branch_target(const unsigned int *instr)
 370 {
 371         if (instr_is_branch_iform(*instr))
 372                 return branch_iform_target(instr);
 373         else if (instr_is_branch_bform(*instr))
 374                 return branch_bform_target(instr);
 375
 376         return 0;
 377 }
 378
 379 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
 380 {
 381         if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
 382                 return branch_target(instr) == addr;
 383
 384         return 0;
 385 }
 386
 387 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
 388 {
 389         unsigned long target;
 390
 391         target = branch_target(src);
 392
 393         if (instr_is_branch_iform(*src))
 394                 return create_branch(dest, target, *src);
 395         else if (instr_is_branch_bform(*src))
 396                 return create_cond_branch(dest, target, *src);
 397
 398         return 0;
 399 }
 400
 401 #ifdef CONFIG_PPC_BOOK3E_64
 402 void __patch_exception(int exc, unsigned long addr)
 403 {
 404         extern unsigned int interrupt_base_book3e;
 405         unsigned int *ibase = &interrupt_base_book3e;
 406
 407         /* Our exceptions vectors start with a NOP and -then- a branch
 408          * to deal with single stepping from userspace which stops on
 409          * the second instruction. Thus we need to patch the second
 410          * instruction of the exception, not the first one
 411          */
 412
 413         patch_branch(ibase + (exc / 4) + 1, addr, 0);
 414 }
 415 #endif
 416
 417 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 418
 419 static void __init test_trampoline(void)
 420 {
 421         asm ("nop;\n");
 422 }
 423
 424 #define check(x)        \
 425         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 426
 427 static void __init test_branch_iform(void)
 428 {
 429         unsigned int instr;
 430         unsigned long addr;
 431
 432         addr = (unsigned long)&instr;
 433
 434         /* The simplest case, branch to self, no flags */
 435         check(instr_is_branch_iform(0x48000000));
 436         /* All bits of target set, and flags */
 437         check(instr_is_branch_iform(0x4bffffff));
 438         /* High bit of opcode set, which is wrong */
 439         check(!instr_is_branch_iform(0xcbffffff));
 440         /* Middle bits of opcode set, which is wrong */
 441         check(!instr_is_branch_iform(0x7bffffff));
 442
 443         /* Simplest case, branch to self with link */
 444         check(instr_is_branch_iform(0x48000001));
 445         /* All bits of targets set */
 446         check(instr_is_branch_iform(0x4bfffffd));
 447         /* Some bits of targets set */
 448         check(instr_is_branch_iform(0x4bff00fd));
 449         /* Must be a valid branch to start with */
 450         check(!instr_is_branch_iform(0x7bfffffd));
 451
 452         /* Absolute branch to 0x100 */
 453         instr = 0x48000103;
 454         check(instr_is_branch_to_addr(&instr, 0x100));
 455         /* Absolute branch to 0x420fc */
 456         instr = 0x480420ff;
 457         check(instr_is_branch_to_addr(&instr, 0x420fc));
 458         /* Maximum positive relative branch, + 20MB - 4B */
 459         instr = 0x49fffffc;
 460         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 461         /* Smallest negative relative branch, - 4B */
 462         instr = 0x4bfffffc;
 463         check(instr_is_branch_to_addr(&instr, addr - 4));
 464         /* Largest negative relative branch, - 32 MB */
 465         instr = 0x4a000000;
 466         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 467
 468         /* Branch to self, with link */
 469         instr = create_branch(&instr, addr, BRANCH_SET_LINK);
 470         check(instr_is_branch_to_addr(&instr, addr));
 471
 472         /* Branch to self - 0x100, with link */
 473         instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
 474         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 475
 476         /* Branch to self + 0x100, no link */
 477         instr = create_branch(&instr, addr + 0x100, 0);
 478         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 479
 480         /* Maximum relative negative offset, - 32 MB */
 481         instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
 482         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 483
 484         /* Out of range relative negative offset, - 32 MB + 4*/
 485         instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
 486         check(instr == 0);
 487
 488         /* Out of range relative positive offset, + 32 MB */
 489         instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
 490         check(instr == 0);
 491
 492         /* Unaligned target */
 493         instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
 494         check(instr == 0);
 495
 496         /* Check flags are masked correctly */
 497         instr = create_branch(&instr, addr, 0xFFFFFFFC);
 498         check(instr_is_branch_to_addr(&instr, addr));
 499         check(instr == 0x48000000);
 500 }
 501
 502 static void __init test_create_function_call(void)
 503 {
 504         unsigned int *iptr;
 505         unsigned long dest;
 506
 507         /* Check we can create a function call */
 508         iptr = (unsigned int *)ppc_function_entry(test_trampoline);
 509         dest = ppc_function_entry(test_create_function_call);
 510         patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
 511         check(instr_is_branch_to_addr(iptr, dest));
 512 }
 513
 514 static void __init test_branch_bform(void)
 515 {
 516         unsigned long addr;
 517         unsigned int *iptr, instr, flags;
 518
 519         iptr = &instr;
 520         addr = (unsigned long)iptr;
 521
 522         /* The simplest case, branch to self, no flags */
 523         check(instr_is_branch_bform(0x40000000));
 524         /* All bits of target set, and flags */
 525         check(instr_is_branch_bform(0x43ffffff));
 526         /* High bit of opcode set, which is wrong */
 527         check(!instr_is_branch_bform(0xc3ffffff));
 528         /* Middle bits of opcode set, which is wrong */
 529         check(!instr_is_branch_bform(0x7bffffff));
 530
 531         /* Absolute conditional branch to 0x100 */
 532         instr = 0x43ff0103;
 533         check(instr_is_branch_to_addr(&instr, 0x100));
 534         /* Absolute conditional branch to 0x20fc */
 535         instr = 0x43ff20ff;
 536         check(instr_is_branch_to_addr(&instr, 0x20fc));
 537         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 538         instr = 0x43ff7ffc;
 539         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 540         /* Smallest negative relative conditional branch, - 4B */
 541         instr = 0x43fffffc;
 542         check(instr_is_branch_to_addr(&instr, addr - 4));
 543         /* Largest negative relative conditional branch, - 32 KB */
 544         instr = 0x43ff8000;
 545         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 546
 547         /* All condition code bits set & link */
 548         flags = 0x3ff000 | BRANCH_SET_LINK;
 549
 550         /* Branch to self */
 551         instr = create_cond_branch(iptr, addr, flags);
 552         check(instr_is_branch_to_addr(&instr, addr));
 553
 554         /* Branch to self - 0x100 */
 555         instr = create_cond_branch(iptr, addr - 0x100, flags);
 556         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 557
 558         /* Branch to self + 0x100 */
 559         instr = create_cond_branch(iptr, addr + 0x100, flags);
 560         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 561
 562         /* Maximum relative negative offset, - 32 KB */
 563         instr = create_cond_branch(iptr, addr - 0x8000, flags);
 564         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 565
 566         /* Out of range relative negative offset, - 32 KB + 4*/
 567         instr = create_cond_branch(iptr, addr - 0x8004, flags);
 568         check(instr == 0);
 569
 570         /* Out of range relative positive offset, + 32 KB */
 571         instr = create_cond_branch(iptr, addr + 0x8000, flags);
 572         check(instr == 0);
 573
 574         /* Unaligned target */
 575         instr = create_cond_branch(iptr, addr + 3, flags);
 576         check(instr == 0);
 577
 578         /* Check flags are masked correctly */
 579         instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
 580         check(instr_is_branch_to_addr(&instr, addr));
 581         check(instr == 0x43FF0000);
 582 }
 583
 584 static void __init test_translate_branch(void)
 585 {
 586         unsigned long addr;
 587         unsigned int *p, *q;
 588         void *buf;
 589
 590         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 591         check(buf);
 592         if (!buf)
 593                 return;
 594
 595         /* Simple case, branch to self moved a little */
 596         p = buf;
 597         addr = (unsigned long)p;
 598         patch_branch(p, addr, 0);
 599         check(instr_is_branch_to_addr(p, addr));
 600         q = p + 1;
 601         patch_instruction(q, translate_branch(q, p));
 602         check(instr_is_branch_to_addr(q, addr));
 603
 604         /* Maximum negative case, move b . to addr + 32 MB */
 605         p = buf;
 606         addr = (unsigned long)p;
 607         patch_branch(p, addr, 0);
 608         q = buf + 0x2000000;
 609         patch_instruction(q, translate_branch(q, p));
 610         check(instr_is_branch_to_addr(p, addr));
 611         check(instr_is_branch_to_addr(q, addr));
 612         check(*q == 0x4a000000);
 613
 614         /* Maximum positive case, move x to x - 32 MB + 4 */
 615         p = buf + 0x2000000;
 616         addr = (unsigned long)p;
 617         patch_branch(p, addr, 0);
 618         q = buf + 4;
 619         patch_instruction(q, translate_branch(q, p));
 620         check(instr_is_branch_to_addr(p, addr));
 621         check(instr_is_branch_to_addr(q, addr));
 622         check(*q == 0x49fffffc);
 623
 624         /* Jump to x + 16 MB moved to x + 20 MB */
 625         p = buf;
 626         addr = 0x1000000 + (unsigned long)buf;
 627         patch_branch(p, addr, BRANCH_SET_LINK);
 628         q = buf + 0x1400000;
 629         patch_instruction(q, translate_branch(q, p));
 630         check(instr_is_branch_to_addr(p, addr));
 631         check(instr_is_branch_to_addr(q, addr));
 632
 633         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 634         p = buf + 0x1000000;
 635         addr = 0x2000000 + (unsigned long)buf;
 636         patch_branch(p, addr, 0);
 637         q = buf + 4;
 638         patch_instruction(q, translate_branch(q, p));
 639         check(instr_is_branch_to_addr(p, addr));
 640         check(instr_is_branch_to_addr(q, addr));
 641
 642
 643         /* Conditional branch tests */
 644
 645         /* Simple case, branch to self moved a little */
 646         p = buf;
 647         addr = (unsigned long)p;
 648         patch_instruction(p, create_cond_branch(p, addr, 0));
 649         check(instr_is_branch_to_addr(p, addr));
 650         q = p + 1;
 651         patch_instruction(q, translate_branch(q, p));
 652         check(instr_is_branch_to_addr(q, addr));
 653
 654         /* Maximum negative case, move b . to addr + 32 KB */
 655         p = buf;
 656         addr = (unsigned long)p;
 657         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 658         q = buf + 0x8000;
 659         patch_instruction(q, translate_branch(q, p));
 660         check(instr_is_branch_to_addr(p, addr));
 661         check(instr_is_branch_to_addr(q, addr));
 662         check(*q == 0x43ff8000);
 663
 664         /* Maximum positive case, move x to x - 32 KB + 4 */
 665         p = buf + 0x8000;
 666         addr = (unsigned long)p;
 667         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 668         q = buf + 4;
 669         patch_instruction(q, translate_branch(q, p));
 670         check(instr_is_branch_to_addr(p, addr));
 671         check(instr_is_branch_to_addr(q, addr));
 672         check(*q == 0x43ff7ffc);
 673
 674         /* Jump to x + 12 KB moved to x + 20 KB */
 675         p = buf;
 676         addr = 0x3000 + (unsigned long)buf;
 677         patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
 678         q = buf + 0x5000;
 679         patch_instruction(q, translate_branch(q, p));
 680         check(instr_is_branch_to_addr(p, addr));
 681         check(instr_is_branch_to_addr(q, addr));
 682
 683         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 684         p = buf + 0x2000;
 685         addr = 0x4000 + (unsigned long)buf;
 686         patch_instruction(p, create_cond_branch(p, addr, 0));
 687         q = buf + 4;
 688         patch_instruction(q, translate_branch(q, p));
 689         check(instr_is_branch_to_addr(p, addr));
 690         check(instr_is_branch_to_addr(q, addr));
 691
 692         /* Free the buffer we were using */
 693         vfree(buf);
 694 }
 695
 696 static int __init test_code_patching(void)
 697 {
 698         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 699
 700         test_branch_iform();
 701         test_branch_bform();
 702         test_create_function_call();
 703         test_translate_branch();
 704
 705         return 0;
 706 }
 707 late_initcall(test_code_patching);
 708
 709 #endif /* CONFIG_CODE_PATCHING_SELFTEST */