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/sections.h>
  25 #include <asm/setup.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         /* Make sure we aren't patching a freed init section */
  33         if (init_mem_is_free && init_section_contains(exec_addr, 4)) {
  34                 pr_debug("Skipping init section patching addr: 0x%px\n", exec_addr);
  35                 return 0;
  36         }
  37
  38         __put_user_size(instr, patch_addr, 4, err);
  39         if (err)
  40                 return err;
  41
  42         asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
  43                                                             "r" (exec_addr));
  44
  45         return 0;
  46 }
  47
  48 int raw_patch_instruction(unsigned int *addr, unsigned int instr)
  49 {
  50         return __patch_instruction(addr, instr, addr);
  51 }
  52
  53 #ifdef CONFIG_STRICT_KERNEL_RWX
  54 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
  55
  56 static int text_area_cpu_up(unsigned int cpu)
  57 {
  58         struct vm_struct *area;
  59
  60         area = get_vm_area(PAGE_SIZE, VM_ALLOC);
  61         if (!area) {
  62                 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
  63                         cpu);
  64                 return -1;
  65         }
  66         this_cpu_write(text_poke_area, area);
  67
  68         return 0;
  69 }
  70
  71 static int text_area_cpu_down(unsigned int cpu)
  72 {
  73         free_vm_area(this_cpu_read(text_poke_area));
  74         return 0;
  75 }
  76
  77 /*
  78  * Run as a late init call. This allows all the boot time patching to be done
  79  * simply by patching the code, and then we're called here prior to
  80  * mark_rodata_ro(), which happens after all init calls are run. Although
  81  * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
  82  * it as being preferable to a kernel that will crash later when someone tries
  83  * to use patch_instruction().
  84  */
  85 static int __init setup_text_poke_area(void)
  86 {
  87         BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
  88                 "powerpc/text_poke:online", text_area_cpu_up,
  89                 text_area_cpu_down));
  90
  91         return 0;
  92 }
  93 late_initcall(setup_text_poke_area);
  94
  95 /*
  96  * This can be called for kernel text or a module.
  97  */
  98 static int map_patch_area(void *addr, unsigned long text_poke_addr)
  99 {
 100         unsigned long pfn;
 101         int err;
 102
 103         if (is_vmalloc_addr(addr))
 104                 pfn = vmalloc_to_pfn(addr);
 105         else
 106                 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
 107
 108         err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT),
 109                                 pgprot_val(PAGE_KERNEL));
 110
 111         pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
 112         if (err)
 113                 return -1;
 114
 115         return 0;
 116 }
 117
 118 static inline int unmap_patch_area(unsigned long addr)
 119 {
 120         pte_t *ptep;
 121         pmd_t *pmdp;
 122         pud_t *pudp;
 123         pgd_t *pgdp;
 124
 125         pgdp = pgd_offset_k(addr);
 126         if (unlikely(!pgdp))
 127                 return -EINVAL;
 128
 129         pudp = pud_offset(pgdp, addr);
 130         if (unlikely(!pudp))
 131                 return -EINVAL;
 132
 133         pmdp = pmd_offset(pudp, addr);
 134         if (unlikely(!pmdp))
 135                 return -EINVAL;
 136
 137         ptep = pte_offset_kernel(pmdp, addr);
 138         if (unlikely(!ptep))
 139                 return -EINVAL;
 140
 141         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 142
 143         /*
 144          * In hash, pte_clear flushes the tlb, in radix, we have to
 145          */
 146         pte_clear(&init_mm, addr, ptep);
 147         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 148
 149         return 0;
 150 }
 151
 152 int patch_instruction(unsigned int *addr, unsigned int instr)
 153 {
 154         int err;
 155         unsigned int *patch_addr = NULL;
 156         unsigned long flags;
 157         unsigned long text_poke_addr;
 158         unsigned long kaddr = (unsigned long)addr;
 159
 160         /*
 161          * During early early boot patch_instruction is called
 162          * when text_poke_area is not ready, but we still need
 163          * to allow patching. We just do the plain old patching
 164          */
 165         if (!this_cpu_read(text_poke_area))
 166                 return raw_patch_instruction(addr, instr);
 167
 168         local_irq_save(flags);
 169
 170         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 171         if (map_patch_area(addr, text_poke_addr)) {
 172                 err = -1;
 173                 goto out;
 174         }
 175
 176         patch_addr = (unsigned int *)(text_poke_addr) +
 177                         ((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
 178
 179         __patch_instruction(addr, instr, patch_addr);
 180
 181         err = unmap_patch_area(text_poke_addr);
 182         if (err)
 183                 pr_warn("failed to unmap %lx\n", text_poke_addr);
 184
 185 out:
 186         local_irq_restore(flags);
 187
 188         return err;
 189 }
 190 #else /* !CONFIG_STRICT_KERNEL_RWX */
 191
 192 int patch_instruction(unsigned int *addr, unsigned int instr)
 193 {
 194         return raw_patch_instruction(addr, instr);
 195 }
 196
 197 #endif /* CONFIG_STRICT_KERNEL_RWX */
 198 NOKPROBE_SYMBOL(patch_instruction);
 199
 200 int patch_branch(unsigned int *addr, unsigned long target, int flags)
 201 {
 202         return patch_instruction(addr, create_branch(addr, target, flags));
 203 }
 204
 205 int patch_branch_site(s32 *site, unsigned long target, int flags)
 206 {
 207         unsigned int *addr;
 208
 209         addr = (unsigned int *)((unsigned long)site + *site);
 210         return patch_instruction(addr, create_branch(addr, target, flags));
 211 }
 212
 213 int patch_instruction_site(s32 *site, unsigned int instr)
 214 {
 215         unsigned int *addr;
 216
 217         addr = (unsigned int *)((unsigned long)site + *site);
 218         return patch_instruction(addr, instr);
 219 }
 220
 221 bool is_offset_in_branch_range(long offset)
 222 {
 223         /*
 224          * Powerpc branch instruction is :
 225          *
 226          *  0         6                 30   31
 227          *  +---------+----------------+---+---+
 228          *  | opcode  |     LI         |AA |LK |
 229          *  +---------+----------------+---+---+
 230          *  Where AA = 0 and LK = 0
 231          *
 232          * LI is a signed 24 bits integer. The real branch offset is computed
 233          * by: imm32 = SignExtend(LI:'0b00', 32);
 234          *
 235          * So the maximum forward branch should be:
 236          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 237          * The maximum backward branch should be:
 238          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 239          */
 240         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 241 }
 242
 243 /*
 244  * Helper to check if a given instruction is a conditional branch
 245  * Derived from the conditional checks in analyse_instr()
 246  */
 247 bool is_conditional_branch(unsigned int instr)
 248 {
 249         unsigned int opcode = instr >> 26;
 250
 251         if (opcode == 16)       /* bc, bca, bcl, bcla */
 252                 return true;
 253         if (opcode == 19) {
 254                 switch ((instr >> 1) & 0x3ff) {
 255                 case 16:        /* bclr, bclrl */
 256                 case 528:       /* bcctr, bcctrl */
 257                 case 560:       /* bctar, bctarl */
 258                         return true;
 259                 }
 260         }
 261         return false;
 262 }
 263 NOKPROBE_SYMBOL(is_conditional_branch);
 264
 265 unsigned int create_branch(const unsigned int *addr,
 266                            unsigned long target, int flags)
 267 {
 268         unsigned int instruction;
 269         long offset;
 270
 271         offset = target;
 272         if (! (flags & BRANCH_ABSOLUTE))
 273                 offset = offset - (unsigned long)addr;
 274
 275         /* Check we can represent the target in the instruction format */
 276         if (!is_offset_in_branch_range(offset))
 277                 return 0;
 278
 279         /* Mask out the flags and target, so they don't step on each other. */
 280         instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
 281
 282         return instruction;
 283 }
 284
 285 unsigned int create_cond_branch(const unsigned int *addr,
 286                                 unsigned long target, int flags)
 287 {
 288         unsigned int instruction;
 289         long offset;
 290
 291         offset = target;
 292         if (! (flags & BRANCH_ABSOLUTE))
 293                 offset = offset - (unsigned long)addr;
 294
 295         /* Check we can represent the target in the instruction format */
 296         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 297                 return 0;
 298
 299         /* Mask out the flags and target, so they don't step on each other. */
 300         instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
 301
 302         return instruction;
 303 }
 304
 305 static unsigned int branch_opcode(unsigned int instr)
 306 {
 307         return (instr >> 26) & 0x3F;
 308 }
 309
 310 static int instr_is_branch_iform(unsigned int instr)
 311 {
 312         return branch_opcode(instr) == 18;
 313 }
 314
 315 static int instr_is_branch_bform(unsigned int instr)
 316 {
 317         return branch_opcode(instr) == 16;
 318 }
 319
 320 int instr_is_relative_branch(unsigned int instr)
 321 {
 322         if (instr & BRANCH_ABSOLUTE)
 323                 return 0;
 324
 325         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 326 }
 327
 328 int instr_is_relative_link_branch(unsigned int instr)
 329 {
 330         return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
 331 }
 332
 333 static unsigned long branch_iform_target(const unsigned int *instr)
 334 {
 335         signed long imm;
 336
 337         imm = *instr & 0x3FFFFFC;
 338
 339         /* If the top bit of the immediate value is set this is negative */
 340         if (imm & 0x2000000)
 341                 imm -= 0x4000000;
 342
 343         if ((*instr & BRANCH_ABSOLUTE) == 0)
 344                 imm += (unsigned long)instr;
 345
 346         return (unsigned long)imm;
 347 }
 348
 349 static unsigned long branch_bform_target(const unsigned int *instr)
 350 {
 351         signed long imm;
 352
 353         imm = *instr & 0xFFFC;
 354
 355         /* If the top bit of the immediate value is set this is negative */
 356         if (imm & 0x8000)
 357                 imm -= 0x10000;
 358
 359         if ((*instr & BRANCH_ABSOLUTE) == 0)
 360                 imm += (unsigned long)instr;
 361
 362         return (unsigned long)imm;
 363 }
 364
 365 unsigned long branch_target(const unsigned int *instr)
 366 {
 367         if (instr_is_branch_iform(*instr))
 368                 return branch_iform_target(instr);
 369         else if (instr_is_branch_bform(*instr))
 370                 return branch_bform_target(instr);
 371
 372         return 0;
 373 }
 374
 375 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
 376 {
 377         if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
 378                 return branch_target(instr) == addr;
 379
 380         return 0;
 381 }
 382
 383 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
 384 {
 385         unsigned long target;
 386
 387         target = branch_target(src);
 388
 389         if (instr_is_branch_iform(*src))
 390                 return create_branch(dest, target, *src);
 391         else if (instr_is_branch_bform(*src))
 392                 return create_cond_branch(dest, target, *src);
 393
 394         return 0;
 395 }
 396
 397 #ifdef CONFIG_PPC_BOOK3E_64
 398 void __patch_exception(int exc, unsigned long addr)
 399 {
 400         extern unsigned int interrupt_base_book3e;
 401         unsigned int *ibase = &interrupt_base_book3e;
 402
 403         /* Our exceptions vectors start with a NOP and -then- a branch
 404          * to deal with single stepping from userspace which stops on
 405          * the second instruction. Thus we need to patch the second
 406          * instruction of the exception, not the first one
 407          */
 408
 409         patch_branch(ibase + (exc / 4) + 1, addr, 0);
 410 }
 411 #endif
 412
 413 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 414
 415 static void __init test_trampoline(void)
 416 {
 417         asm ("nop;\n");
 418 }
 419
 420 #define check(x)        \
 421         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 422
 423 static void __init test_branch_iform(void)
 424 {
 425         unsigned int instr;
 426         unsigned long addr;
 427
 428         addr = (unsigned long)&instr;
 429
 430         /* The simplest case, branch to self, no flags */
 431         check(instr_is_branch_iform(0x48000000));
 432         /* All bits of target set, and flags */
 433         check(instr_is_branch_iform(0x4bffffff));
 434         /* High bit of opcode set, which is wrong */
 435         check(!instr_is_branch_iform(0xcbffffff));
 436         /* Middle bits of opcode set, which is wrong */
 437         check(!instr_is_branch_iform(0x7bffffff));
 438
 439         /* Simplest case, branch to self with link */
 440         check(instr_is_branch_iform(0x48000001));
 441         /* All bits of targets set */
 442         check(instr_is_branch_iform(0x4bfffffd));
 443         /* Some bits of targets set */
 444         check(instr_is_branch_iform(0x4bff00fd));
 445         /* Must be a valid branch to start with */
 446         check(!instr_is_branch_iform(0x7bfffffd));
 447
 448         /* Absolute branch to 0x100 */
 449         instr = 0x48000103;
 450         check(instr_is_branch_to_addr(&instr, 0x100));
 451         /* Absolute branch to 0x420fc */
 452         instr = 0x480420ff;
 453         check(instr_is_branch_to_addr(&instr, 0x420fc));
 454         /* Maximum positive relative branch, + 20MB - 4B */
 455         instr = 0x49fffffc;
 456         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 457         /* Smallest negative relative branch, - 4B */
 458         instr = 0x4bfffffc;
 459         check(instr_is_branch_to_addr(&instr, addr - 4));
 460         /* Largest negative relative branch, - 32 MB */
 461         instr = 0x4a000000;
 462         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 463
 464         /* Branch to self, with link */
 465         instr = create_branch(&instr, addr, BRANCH_SET_LINK);
 466         check(instr_is_branch_to_addr(&instr, addr));
 467
 468         /* Branch to self - 0x100, with link */
 469         instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
 470         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 471
 472         /* Branch to self + 0x100, no link */
 473         instr = create_branch(&instr, addr + 0x100, 0);
 474         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 475
 476         /* Maximum relative negative offset, - 32 MB */
 477         instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
 478         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 479
 480         /* Out of range relative negative offset, - 32 MB + 4*/
 481         instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
 482         check(instr == 0);
 483
 484         /* Out of range relative positive offset, + 32 MB */
 485         instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
 486         check(instr == 0);
 487
 488         /* Unaligned target */
 489         instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
 490         check(instr == 0);
 491
 492         /* Check flags are masked correctly */
 493         instr = create_branch(&instr, addr, 0xFFFFFFFC);
 494         check(instr_is_branch_to_addr(&instr, addr));
 495         check(instr == 0x48000000);
 496 }
 497
 498 static void __init test_create_function_call(void)
 499 {
 500         unsigned int *iptr;
 501         unsigned long dest;
 502
 503         /* Check we can create a function call */
 504         iptr = (unsigned int *)ppc_function_entry(test_trampoline);
 505         dest = ppc_function_entry(test_create_function_call);
 506         patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
 507         check(instr_is_branch_to_addr(iptr, dest));
 508 }
 509
 510 static void __init test_branch_bform(void)
 511 {
 512         unsigned long addr;
 513         unsigned int *iptr, instr, flags;
 514
 515         iptr = &instr;
 516         addr = (unsigned long)iptr;
 517
 518         /* The simplest case, branch to self, no flags */
 519         check(instr_is_branch_bform(0x40000000));
 520         /* All bits of target set, and flags */
 521         check(instr_is_branch_bform(0x43ffffff));
 522         /* High bit of opcode set, which is wrong */
 523         check(!instr_is_branch_bform(0xc3ffffff));
 524         /* Middle bits of opcode set, which is wrong */
 525         check(!instr_is_branch_bform(0x7bffffff));
 526
 527         /* Absolute conditional branch to 0x100 */
 528         instr = 0x43ff0103;
 529         check(instr_is_branch_to_addr(&instr, 0x100));
 530         /* Absolute conditional branch to 0x20fc */
 531         instr = 0x43ff20ff;
 532         check(instr_is_branch_to_addr(&instr, 0x20fc));
 533         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 534         instr = 0x43ff7ffc;
 535         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 536         /* Smallest negative relative conditional branch, - 4B */
 537         instr = 0x43fffffc;
 538         check(instr_is_branch_to_addr(&instr, addr - 4));
 539         /* Largest negative relative conditional branch, - 32 KB */
 540         instr = 0x43ff8000;
 541         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 542
 543         /* All condition code bits set & link */
 544         flags = 0x3ff000 | BRANCH_SET_LINK;
 545
 546         /* Branch to self */
 547         instr = create_cond_branch(iptr, addr, flags);
 548         check(instr_is_branch_to_addr(&instr, addr));
 549
 550         /* Branch to self - 0x100 */
 551         instr = create_cond_branch(iptr, addr - 0x100, flags);
 552         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 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         /* Maximum relative negative offset, - 32 KB */
 559         instr = create_cond_branch(iptr, addr - 0x8000, flags);
 560         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 561
 562         /* Out of range relative negative offset, - 32 KB + 4*/
 563         instr = create_cond_branch(iptr, addr - 0x8004, flags);
 564         check(instr == 0);
 565
 566         /* Out of range relative positive offset, + 32 KB */
 567         instr = create_cond_branch(iptr, addr + 0x8000, flags);
 568         check(instr == 0);
 569
 570         /* Unaligned target */
 571         instr = create_cond_branch(iptr, addr + 3, flags);
 572         check(instr == 0);
 573
 574         /* Check flags are masked correctly */
 575         instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
 576         check(instr_is_branch_to_addr(&instr, addr));
 577         check(instr == 0x43FF0000);
 578 }
 579
 580 static void __init test_translate_branch(void)
 581 {
 582         unsigned long addr;
 583         unsigned int *p, *q;
 584         void *buf;
 585
 586         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 587         check(buf);
 588         if (!buf)
 589                 return;
 590
 591         /* Simple case, branch to self moved a little */
 592         p = buf;
 593         addr = (unsigned long)p;
 594         patch_branch(p, addr, 0);
 595         check(instr_is_branch_to_addr(p, addr));
 596         q = p + 1;
 597         patch_instruction(q, translate_branch(q, p));
 598         check(instr_is_branch_to_addr(q, addr));
 599
 600         /* Maximum negative case, move b . to addr + 32 MB */
 601         p = buf;
 602         addr = (unsigned long)p;
 603         patch_branch(p, addr, 0);
 604         q = buf + 0x2000000;
 605         patch_instruction(q, translate_branch(q, p));
 606         check(instr_is_branch_to_addr(p, addr));
 607         check(instr_is_branch_to_addr(q, addr));
 608         check(*q == 0x4a000000);
 609
 610         /* Maximum positive case, move x to x - 32 MB + 4 */
 611         p = buf + 0x2000000;
 612         addr = (unsigned long)p;
 613         patch_branch(p, addr, 0);
 614         q = buf + 4;
 615         patch_instruction(q, translate_branch(q, p));
 616         check(instr_is_branch_to_addr(p, addr));
 617         check(instr_is_branch_to_addr(q, addr));
 618         check(*q == 0x49fffffc);
 619
 620         /* Jump to x + 16 MB moved to x + 20 MB */
 621         p = buf;
 622         addr = 0x1000000 + (unsigned long)buf;
 623         patch_branch(p, addr, BRANCH_SET_LINK);
 624         q = buf + 0x1400000;
 625         patch_instruction(q, translate_branch(q, p));
 626         check(instr_is_branch_to_addr(p, addr));
 627         check(instr_is_branch_to_addr(q, addr));
 628
 629         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 630         p = buf + 0x1000000;
 631         addr = 0x2000000 + (unsigned long)buf;
 632         patch_branch(p, addr, 0);
 633         q = buf + 4;
 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
 639         /* Conditional branch tests */
 640
 641         /* Simple case, branch to self moved a little */
 642         p = buf;
 643         addr = (unsigned long)p;
 644         patch_instruction(p, create_cond_branch(p, addr, 0));
 645         check(instr_is_branch_to_addr(p, addr));
 646         q = p + 1;
 647         patch_instruction(q, translate_branch(q, p));
 648         check(instr_is_branch_to_addr(q, addr));
 649
 650         /* Maximum negative case, move b . to addr + 32 KB */
 651         p = buf;
 652         addr = (unsigned long)p;
 653         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 654         q = buf + 0x8000;
 655         patch_instruction(q, translate_branch(q, p));
 656         check(instr_is_branch_to_addr(p, addr));
 657         check(instr_is_branch_to_addr(q, addr));
 658         check(*q == 0x43ff8000);
 659
 660         /* Maximum positive case, move x to x - 32 KB + 4 */
 661         p = buf + 0x8000;
 662         addr = (unsigned long)p;
 663         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 664         q = buf + 4;
 665         patch_instruction(q, translate_branch(q, p));
 666         check(instr_is_branch_to_addr(p, addr));
 667         check(instr_is_branch_to_addr(q, addr));
 668         check(*q == 0x43ff7ffc);
 669
 670         /* Jump to x + 12 KB moved to x + 20 KB */
 671         p = buf;
 672         addr = 0x3000 + (unsigned long)buf;
 673         patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
 674         q = buf + 0x5000;
 675         patch_instruction(q, translate_branch(q, p));
 676         check(instr_is_branch_to_addr(p, addr));
 677         check(instr_is_branch_to_addr(q, addr));
 678
 679         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 680         p = buf + 0x2000;
 681         addr = 0x4000 + (unsigned long)buf;
 682         patch_instruction(p, create_cond_branch(p, addr, 0));
 683         q = buf + 4;
 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         /* Free the buffer we were using */
 689         vfree(buf);
 690 }
 691
 692 static int __init test_code_patching(void)
 693 {
 694         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 695
 696         test_branch_iform();
 697         test_branch_bform();
 698         test_create_function_call();
 699         test_translate_branch();
 700
 701         return 0;
 702 }
 703 late_initcall(test_code_patching);
 704
 705 #endif /* CONFIG_CODE_PATCHING_SELFTEST */