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
  26 static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
  27                                unsigned int *patch_addr)
  28 {
  29         int err;
  30
  31         __put_user_size(instr, patch_addr, 4, err);
  32         if (err)
  33                 return err;
  34
  35         asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
  36                                                             "r" (exec_addr));
  37
  38         return 0;
  39 }
  40
  41 int raw_patch_instruction(unsigned int *addr, unsigned int instr)
  42 {
  43         return __patch_instruction(addr, instr, addr);
  44 }
  45
  46 #ifdef CONFIG_STRICT_KERNEL_RWX
  47 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
  48
  49 static int text_area_cpu_up(unsigned int cpu)
  50 {
  51         struct vm_struct *area;
  52
  53         area = get_vm_area(PAGE_SIZE, VM_ALLOC);
  54         if (!area) {
  55                 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
  56                         cpu);
  57                 return -1;
  58         }
  59         this_cpu_write(text_poke_area, area);
  60
  61         return 0;
  62 }
  63
  64 static int text_area_cpu_down(unsigned int cpu)
  65 {
  66         free_vm_area(this_cpu_read(text_poke_area));
  67         return 0;
  68 }
  69
  70 /*
  71  * Run as a late init call. This allows all the boot time patching to be done
  72  * simply by patching the code, and then we're called here prior to
  73  * mark_rodata_ro(), which happens after all init calls are run. Although
  74  * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
  75  * it as being preferable to a kernel that will crash later when someone tries
  76  * to use patch_instruction().
  77  */
  78 static int __init setup_text_poke_area(void)
  79 {
  80         BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
  81                 "powerpc/text_poke:online", text_area_cpu_up,
  82                 text_area_cpu_down));
  83
  84         return 0;
  85 }
  86 late_initcall(setup_text_poke_area);
  87
  88 /*
  89  * This can be called for kernel text or a module.
  90  */
  91 static int map_patch_area(void *addr, unsigned long text_poke_addr)
  92 {
  93         unsigned long pfn;
  94         int err;
  95
  96         if (is_vmalloc_addr(addr))
  97                 pfn = vmalloc_to_pfn(addr);
  98         else
  99                 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
 100
 101         err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT),
 102                                 pgprot_val(PAGE_KERNEL));
 103
 104         pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
 105         if (err)
 106                 return -1;
 107
 108         return 0;
 109 }
 110
 111 static inline int unmap_patch_area(unsigned long addr)
 112 {
 113         pte_t *ptep;
 114         pmd_t *pmdp;
 115         pud_t *pudp;
 116         pgd_t *pgdp;
 117
 118         pgdp = pgd_offset_k(addr);
 119         if (unlikely(!pgdp))
 120                 return -EINVAL;
 121
 122         pudp = pud_offset(pgdp, addr);
 123         if (unlikely(!pudp))
 124                 return -EINVAL;
 125
 126         pmdp = pmd_offset(pudp, addr);
 127         if (unlikely(!pmdp))
 128                 return -EINVAL;
 129
 130         ptep = pte_offset_kernel(pmdp, addr);
 131         if (unlikely(!ptep))
 132                 return -EINVAL;
 133
 134         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 135
 136         /*
 137          * In hash, pte_clear flushes the tlb, in radix, we have to
 138          */
 139         pte_clear(&init_mm, addr, ptep);
 140         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 141
 142         return 0;
 143 }
 144
 145 static int do_patch_instruction(unsigned int *addr, unsigned int instr)
 146 {
 147         int err;
 148         unsigned int *patch_addr = NULL;
 149         unsigned long flags;
 150         unsigned long text_poke_addr;
 151         unsigned long kaddr = (unsigned long)addr;
 152
 153         /*
 154          * During early early boot patch_instruction is called
 155          * when text_poke_area is not ready, but we still need
 156          * to allow patching. We just do the plain old patching
 157          */
 158         if (!this_cpu_read(text_poke_area))
 159                 return raw_patch_instruction(addr, instr);
 160
 161         local_irq_save(flags);
 162
 163         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 164         if (map_patch_area(addr, text_poke_addr)) {
 165                 err = -1;
 166                 goto out;
 167         }
 168
 169         patch_addr = (unsigned int *)(text_poke_addr) +
 170                         ((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
 171
 172         __patch_instruction(addr, instr, patch_addr);
 173
 174         err = unmap_patch_area(text_poke_addr);
 175         if (err)
 176                 pr_warn("failed to unmap %lx\n", text_poke_addr);
 177
 178 out:
 179         local_irq_restore(flags);
 180
 181         return err;
 182 }
 183 #else /* !CONFIG_STRICT_KERNEL_RWX */
 184
 185 static int do_patch_instruction(unsigned int *addr, unsigned int instr)
 186 {
 187         return raw_patch_instruction(addr, instr);
 188 }
 189
 190 #endif /* CONFIG_STRICT_KERNEL_RWX */
 191
 192 int patch_instruction(unsigned int *addr, unsigned int instr)
 193 {
 194         /* Make sure we aren't patching a freed init section */
 195         if (init_mem_is_free && init_section_contains(addr, 4)) {
 196                 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
 197                 return 0;
 198         }
 199         return do_patch_instruction(addr, instr);
 200 }
 201 NOKPROBE_SYMBOL(patch_instruction);
 202
 203 int patch_branch(unsigned int *addr, unsigned long target, int flags)
 204 {
 205         return patch_instruction(addr, create_branch(addr, target, flags));
 206 }
 207
 208 int patch_branch_site(s32 *site, unsigned long target, int flags)
 209 {
 210         unsigned int *addr;
 211
 212         addr = (unsigned int *)((unsigned long)site + *site);
 213         return patch_instruction(addr, create_branch(addr, target, flags));
 214 }
 215
 216 int patch_instruction_site(s32 *site, unsigned int instr)
 217 {
 218         unsigned int *addr;
 219
 220         addr = (unsigned int *)((unsigned long)site + *site);
 221         return patch_instruction(addr, instr);
 222 }
 223
 224 bool is_offset_in_branch_range(long offset)
 225 {
 226         /*
 227          * Powerpc branch instruction is :
 228          *
 229          *  0         6                 30   31
 230          *  +---------+----------------+---+---+
 231          *  | opcode  |     LI         |AA |LK |
 232          *  +---------+----------------+---+---+
 233          *  Where AA = 0 and LK = 0
 234          *
 235          * LI is a signed 24 bits integer. The real branch offset is computed
 236          * by: imm32 = SignExtend(LI:'0b00', 32);
 237          *
 238          * So the maximum forward branch should be:
 239          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 240          * The maximum backward branch should be:
 241          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 242          */
 243         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 244 }
 245
 246 /*
 247  * Helper to check if a given instruction is a conditional branch
 248  * Derived from the conditional checks in analyse_instr()
 249  */
 250 bool is_conditional_branch(unsigned int instr)
 251 {
 252         unsigned int opcode = instr >> 26;
 253
 254         if (opcode == 16)       /* bc, bca, bcl, bcla */
 255                 return true;
 256         if (opcode == 19) {
 257                 switch ((instr >> 1) & 0x3ff) {
 258                 case 16:        /* bclr, bclrl */
 259                 case 528:       /* bcctr, bcctrl */
 260                 case 560:       /* bctar, bctarl */
 261                         return true;
 262                 }
 263         }
 264         return false;
 265 }
 266 NOKPROBE_SYMBOL(is_conditional_branch);
 267
 268 unsigned int create_branch(const unsigned int *addr,
 269                            unsigned long target, int flags)
 270 {
 271         unsigned int instruction;
 272         long offset;
 273
 274         offset = target;
 275         if (! (flags & BRANCH_ABSOLUTE))
 276                 offset = offset - (unsigned long)addr;
 277
 278         /* Check we can represent the target in the instruction format */
 279         if (!is_offset_in_branch_range(offset))
 280                 return 0;
 281
 282         /* Mask out the flags and target, so they don't step on each other. */
 283         instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
 284
 285         return instruction;
 286 }
 287
 288 unsigned int create_cond_branch(const unsigned int *addr,
 289                                 unsigned long target, int flags)
 290 {
 291         unsigned int instruction;
 292         long offset;
 293
 294         offset = target;
 295         if (! (flags & BRANCH_ABSOLUTE))
 296                 offset = offset - (unsigned long)addr;
 297
 298         /* Check we can represent the target in the instruction format */
 299         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 300                 return 0;
 301
 302         /* Mask out the flags and target, so they don't step on each other. */
 303         instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
 304
 305         return instruction;
 306 }
 307
 308 static unsigned int branch_opcode(unsigned int instr)
 309 {
 310         return (instr >> 26) & 0x3F;
 311 }
 312
 313 static int instr_is_branch_iform(unsigned int instr)
 314 {
 315         return branch_opcode(instr) == 18;
 316 }
 317
 318 static int instr_is_branch_bform(unsigned int instr)
 319 {
 320         return branch_opcode(instr) == 16;
 321 }
 322
 323 int instr_is_relative_branch(unsigned int instr)
 324 {
 325         if (instr & BRANCH_ABSOLUTE)
 326                 return 0;
 327
 328         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 329 }
 330
 331 int instr_is_relative_link_branch(unsigned int instr)
 332 {
 333         return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK);
 334 }
 335
 336 static unsigned long branch_iform_target(const unsigned int *instr)
 337 {
 338         signed long imm;
 339
 340         imm = *instr & 0x3FFFFFC;
 341
 342         /* If the top bit of the immediate value is set this is negative */
 343         if (imm & 0x2000000)
 344                 imm -= 0x4000000;
 345
 346         if ((*instr & BRANCH_ABSOLUTE) == 0)
 347                 imm += (unsigned long)instr;
 348
 349         return (unsigned long)imm;
 350 }
 351
 352 static unsigned long branch_bform_target(const unsigned int *instr)
 353 {
 354         signed long imm;
 355
 356         imm = *instr & 0xFFFC;
 357
 358         /* If the top bit of the immediate value is set this is negative */
 359         if (imm & 0x8000)
 360                 imm -= 0x10000;
 361
 362         if ((*instr & BRANCH_ABSOLUTE) == 0)
 363                 imm += (unsigned long)instr;
 364
 365         return (unsigned long)imm;
 366 }
 367
 368 unsigned long branch_target(const unsigned int *instr)
 369 {
 370         if (instr_is_branch_iform(*instr))
 371                 return branch_iform_target(instr);
 372         else if (instr_is_branch_bform(*instr))
 373                 return branch_bform_target(instr);
 374
 375         return 0;
 376 }
 377
 378 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
 379 {
 380         if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr))
 381                 return branch_target(instr) == addr;
 382
 383         return 0;
 384 }
 385
 386 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
 387 {
 388         unsigned long target;
 389
 390         target = branch_target(src);
 391
 392         if (instr_is_branch_iform(*src))
 393                 return create_branch(dest, target, *src);
 394         else if (instr_is_branch_bform(*src))
 395                 return create_cond_branch(dest, target, *src);
 396
 397         return 0;
 398 }
 399
 400 #ifdef CONFIG_PPC_BOOK3E_64
 401 void __patch_exception(int exc, unsigned long addr)
 402 {
 403         extern unsigned int interrupt_base_book3e;
 404         unsigned int *ibase = &interrupt_base_book3e;
 405
 406         /* Our exceptions vectors start with a NOP and -then- a branch
 407          * to deal with single stepping from userspace which stops on
 408          * the second instruction. Thus we need to patch the second
 409          * instruction of the exception, not the first one
 410          */
 411
 412         patch_branch(ibase + (exc / 4) + 1, addr, 0);
 413 }
 414 #endif
 415
 416 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 417
 418 static void __init test_trampoline(void)
 419 {
 420         asm ("nop;\n");
 421 }
 422
 423 #define check(x)        \
 424         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 425
 426 static void __init test_branch_iform(void)
 427 {
 428         unsigned int instr;
 429         unsigned long addr;
 430
 431         addr = (unsigned long)&instr;
 432
 433         /* The simplest case, branch to self, no flags */
 434         check(instr_is_branch_iform(0x48000000));
 435         /* All bits of target set, and flags */
 436         check(instr_is_branch_iform(0x4bffffff));
 437         /* High bit of opcode set, which is wrong */
 438         check(!instr_is_branch_iform(0xcbffffff));
 439         /* Middle bits of opcode set, which is wrong */
 440         check(!instr_is_branch_iform(0x7bffffff));
 441
 442         /* Simplest case, branch to self with link */
 443         check(instr_is_branch_iform(0x48000001));
 444         /* All bits of targets set */
 445         check(instr_is_branch_iform(0x4bfffffd));
 446         /* Some bits of targets set */
 447         check(instr_is_branch_iform(0x4bff00fd));
 448         /* Must be a valid branch to start with */
 449         check(!instr_is_branch_iform(0x7bfffffd));
 450
 451         /* Absolute branch to 0x100 */
 452         instr = 0x48000103;
 453         check(instr_is_branch_to_addr(&instr, 0x100));
 454         /* Absolute branch to 0x420fc */
 455         instr = 0x480420ff;
 456         check(instr_is_branch_to_addr(&instr, 0x420fc));
 457         /* Maximum positive relative branch, + 20MB - 4B */
 458         instr = 0x49fffffc;
 459         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 460         /* Smallest negative relative branch, - 4B */
 461         instr = 0x4bfffffc;
 462         check(instr_is_branch_to_addr(&instr, addr - 4));
 463         /* Largest negative relative branch, - 32 MB */
 464         instr = 0x4a000000;
 465         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 466
 467         /* Branch to self, with link */
 468         instr = create_branch(&instr, addr, BRANCH_SET_LINK);
 469         check(instr_is_branch_to_addr(&instr, addr));
 470
 471         /* Branch to self - 0x100, with link */
 472         instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
 473         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 474
 475         /* Branch to self + 0x100, no link */
 476         instr = create_branch(&instr, addr + 0x100, 0);
 477         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 478
 479         /* Maximum relative negative offset, - 32 MB */
 480         instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
 481         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 482
 483         /* Out of range relative negative offset, - 32 MB + 4*/
 484         instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
 485         check(instr == 0);
 486
 487         /* Out of range relative positive offset, + 32 MB */
 488         instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
 489         check(instr == 0);
 490
 491         /* Unaligned target */
 492         instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
 493         check(instr == 0);
 494
 495         /* Check flags are masked correctly */
 496         instr = create_branch(&instr, addr, 0xFFFFFFFC);
 497         check(instr_is_branch_to_addr(&instr, addr));
 498         check(instr == 0x48000000);
 499 }
 500
 501 static void __init test_create_function_call(void)
 502 {
 503         unsigned int *iptr;
 504         unsigned long dest;
 505
 506         /* Check we can create a function call */
 507         iptr = (unsigned int *)ppc_function_entry(test_trampoline);
 508         dest = ppc_function_entry(test_create_function_call);
 509         patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
 510         check(instr_is_branch_to_addr(iptr, dest));
 511 }
 512
 513 static void __init test_branch_bform(void)
 514 {
 515         unsigned long addr;
 516         unsigned int *iptr, instr, flags;
 517
 518         iptr = &instr;
 519         addr = (unsigned long)iptr;
 520
 521         /* The simplest case, branch to self, no flags */
 522         check(instr_is_branch_bform(0x40000000));
 523         /* All bits of target set, and flags */
 524         check(instr_is_branch_bform(0x43ffffff));
 525         /* High bit of opcode set, which is wrong */
 526         check(!instr_is_branch_bform(0xc3ffffff));
 527         /* Middle bits of opcode set, which is wrong */
 528         check(!instr_is_branch_bform(0x7bffffff));
 529
 530         /* Absolute conditional branch to 0x100 */
 531         instr = 0x43ff0103;
 532         check(instr_is_branch_to_addr(&instr, 0x100));
 533         /* Absolute conditional branch to 0x20fc */
 534         instr = 0x43ff20ff;
 535         check(instr_is_branch_to_addr(&instr, 0x20fc));
 536         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 537         instr = 0x43ff7ffc;
 538         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 539         /* Smallest negative relative conditional branch, - 4B */
 540         instr = 0x43fffffc;
 541         check(instr_is_branch_to_addr(&instr, addr - 4));
 542         /* Largest negative relative conditional branch, - 32 KB */
 543         instr = 0x43ff8000;
 544         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 545
 546         /* All condition code bits set & link */
 547         flags = 0x3ff000 | BRANCH_SET_LINK;
 548
 549         /* Branch to self */
 550         instr = create_cond_branch(iptr, addr, flags);
 551         check(instr_is_branch_to_addr(&instr, addr));
 552
 553         /* Branch to self - 0x100 */
 554         instr = create_cond_branch(iptr, addr - 0x100, flags);
 555         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 556
 557         /* Branch to self + 0x100 */
 558         instr = create_cond_branch(iptr, addr + 0x100, flags);
 559         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 560
 561         /* Maximum relative negative offset, - 32 KB */
 562         instr = create_cond_branch(iptr, addr - 0x8000, flags);
 563         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 564
 565         /* Out of range relative negative offset, - 32 KB + 4*/
 566         instr = create_cond_branch(iptr, addr - 0x8004, flags);
 567         check(instr == 0);
 568
 569         /* Out of range relative positive offset, + 32 KB */
 570         instr = create_cond_branch(iptr, addr + 0x8000, flags);
 571         check(instr == 0);
 572
 573         /* Unaligned target */
 574         instr = create_cond_branch(iptr, addr + 3, flags);
 575         check(instr == 0);
 576
 577         /* Check flags are masked correctly */
 578         instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
 579         check(instr_is_branch_to_addr(&instr, addr));
 580         check(instr == 0x43FF0000);
 581 }
 582
 583 static void __init test_translate_branch(void)
 584 {
 585         unsigned long addr;
 586         unsigned int *p, *q;
 587         void *buf;
 588
 589         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 590         check(buf);
 591         if (!buf)
 592                 return;
 593
 594         /* Simple case, branch to self moved a little */
 595         p = buf;
 596         addr = (unsigned long)p;
 597         patch_branch(p, addr, 0);
 598         check(instr_is_branch_to_addr(p, addr));
 599         q = p + 1;
 600         patch_instruction(q, translate_branch(q, p));
 601         check(instr_is_branch_to_addr(q, addr));
 602
 603         /* Maximum negative case, move b . to addr + 32 MB */
 604         p = buf;
 605         addr = (unsigned long)p;
 606         patch_branch(p, addr, 0);
 607         q = buf + 0x2000000;
 608         patch_instruction(q, translate_branch(q, p));
 609         check(instr_is_branch_to_addr(p, addr));
 610         check(instr_is_branch_to_addr(q, addr));
 611         check(*q == 0x4a000000);
 612
 613         /* Maximum positive case, move x to x - 32 MB + 4 */
 614         p = buf + 0x2000000;
 615         addr = (unsigned long)p;
 616         patch_branch(p, addr, 0);
 617         q = buf + 4;
 618         patch_instruction(q, translate_branch(q, p));
 619         check(instr_is_branch_to_addr(p, addr));
 620         check(instr_is_branch_to_addr(q, addr));
 621         check(*q == 0x49fffffc);
 622
 623         /* Jump to x + 16 MB moved to x + 20 MB */
 624         p = buf;
 625         addr = 0x1000000 + (unsigned long)buf;
 626         patch_branch(p, addr, BRANCH_SET_LINK);
 627         q = buf + 0x1400000;
 628         patch_instruction(q, translate_branch(q, p));
 629         check(instr_is_branch_to_addr(p, addr));
 630         check(instr_is_branch_to_addr(q, addr));
 631
 632         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 633         p = buf + 0x1000000;
 634         addr = 0x2000000 + (unsigned long)buf;
 635         patch_branch(p, addr, 0);
 636         q = buf + 4;
 637         patch_instruction(q, translate_branch(q, p));
 638         check(instr_is_branch_to_addr(p, addr));
 639         check(instr_is_branch_to_addr(q, addr));
 640
 641
 642         /* Conditional branch tests */
 643
 644         /* Simple case, branch to self moved a little */
 645         p = buf;
 646         addr = (unsigned long)p;
 647         patch_instruction(p, create_cond_branch(p, addr, 0));
 648         check(instr_is_branch_to_addr(p, addr));
 649         q = p + 1;
 650         patch_instruction(q, translate_branch(q, p));
 651         check(instr_is_branch_to_addr(q, addr));
 652
 653         /* Maximum negative case, move b . to addr + 32 KB */
 654         p = buf;
 655         addr = (unsigned long)p;
 656         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 657         q = buf + 0x8000;
 658         patch_instruction(q, translate_branch(q, p));
 659         check(instr_is_branch_to_addr(p, addr));
 660         check(instr_is_branch_to_addr(q, addr));
 661         check(*q == 0x43ff8000);
 662
 663         /* Maximum positive case, move x to x - 32 KB + 4 */
 664         p = buf + 0x8000;
 665         addr = (unsigned long)p;
 666         patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
 667         q = buf + 4;
 668         patch_instruction(q, translate_branch(q, p));
 669         check(instr_is_branch_to_addr(p, addr));
 670         check(instr_is_branch_to_addr(q, addr));
 671         check(*q == 0x43ff7ffc);
 672
 673         /* Jump to x + 12 KB moved to x + 20 KB */
 674         p = buf;
 675         addr = 0x3000 + (unsigned long)buf;
 676         patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
 677         q = buf + 0x5000;
 678         patch_instruction(q, translate_branch(q, p));
 679         check(instr_is_branch_to_addr(p, addr));
 680         check(instr_is_branch_to_addr(q, addr));
 681
 682         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 683         p = buf + 0x2000;
 684         addr = 0x4000 + (unsigned long)buf;
 685         patch_instruction(p, create_cond_branch(p, addr, 0));
 686         q = buf + 4;
 687         patch_instruction(q, translate_branch(q, p));
 688         check(instr_is_branch_to_addr(p, addr));
 689         check(instr_is_branch_to_addr(q, addr));
 690
 691         /* Free the buffer we were using */
 692         vfree(buf);
 693 }
 694
 695 static int __init test_code_patching(void)
 696 {
 697         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 698
 699         test_branch_iform();
 700         test_branch_bform();
 701         test_create_function_call();
 702         test_translate_branch();
 703
 704         return 0;
 705 }
 706 late_initcall(test_code_patching);
 707
 708 #endif /* CONFIG_CODE_PATCHING_SELFTEST */