linux/arch/powerpc/lib/code-patching.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *  Copyright 2008 Michael Ellerman, IBM Corporation.
   4 */
   5
   6#include <linux/kernel.h>
   7#include <linux/kprobes.h>
   8#include <linux/vmalloc.h>
   9#include <linux/init.h>
  10#include <linux/mm.h>
  11#include <linux/cpuhotplug.h>
  12#include <linux/slab.h>
  13#include <linux/uaccess.h>
  14
  15#include <asm/tlbflush.h>
  16#include <asm/page.h>
  17#include <asm/code-patching.h>
  18#include <asm/setup.h>
  19#include <asm/inst.h>
  20
  21static int __patch_instruction(u32 *exec_addr, struct ppc_inst instr, u32 *patch_addr)
  22{
  23        if (!ppc_inst_prefixed(instr)) {
  24                u32 val = ppc_inst_val(instr);
  25
  26                __put_kernel_nofault(patch_addr, &val, u32, failed);
  27        } else {
  28                u64 val = ppc_inst_as_ulong(instr);
  29
  30                __put_kernel_nofault(patch_addr, &val, u64, failed);
  31        }
  32
  33        asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
  34                                                            "r" (exec_addr));
  35
  36        return 0;
  37
  38failed:
  39        return -EFAULT;
  40}
  41
  42int raw_patch_instruction(u32 *addr, struct ppc_inst instr)
  43{
  44        return __patch_instruction(addr, instr, addr);
  45}
  46
  47#ifdef CONFIG_STRICT_KERNEL_RWX
  48static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
  49
  50static 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
  65static int text_area_cpu_down(unsigned int cpu)
  66{
  67        free_vm_area(this_cpu_read(text_poke_area));
  68        return 0;
  69}
  70
  71/*
  72 * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and
  73 * we judge it as being preferable to a kernel that will crash later when
  74 * someone tries to use patch_instruction().
  75 */
  76void __init poking_init(void)
  77{
  78        BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
  79                "powerpc/text_poke:online", text_area_cpu_up,
  80                text_area_cpu_down));
  81}
  82
  83/*
  84 * This can be called for kernel text or a module.
  85 */
  86static int map_patch_area(void *addr, unsigned long text_poke_addr)
  87{
  88        unsigned long pfn;
  89        int err;
  90
  91        if (is_vmalloc_or_module_addr(addr))
  92                pfn = vmalloc_to_pfn(addr);
  93        else
  94                pfn = __pa_symbol(addr) >> PAGE_SHIFT;
  95
  96        err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
  97
  98        pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
  99        if (err)
 100                return -1;
 101
 102        return 0;
 103}
 104
 105static inline int unmap_patch_area(unsigned long addr)
 106{
 107        pte_t *ptep;
 108        pmd_t *pmdp;
 109        pud_t *pudp;
 110        p4d_t *p4dp;
 111        pgd_t *pgdp;
 112
 113        pgdp = pgd_offset_k(addr);
 114        if (unlikely(!pgdp))
 115                return -EINVAL;
 116
 117        p4dp = p4d_offset(pgdp, addr);
 118        if (unlikely(!p4dp))
 119                return -EINVAL;
 120
 121        pudp = pud_offset(p4dp, addr);
 122        if (unlikely(!pudp))
 123                return -EINVAL;
 124
 125        pmdp = pmd_offset(pudp, addr);
 126        if (unlikely(!pmdp))
 127                return -EINVAL;
 128
 129        ptep = pte_offset_kernel(pmdp, addr);
 130        if (unlikely(!ptep))
 131                return -EINVAL;
 132
 133        pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 134
 135        /*
 136         * In hash, pte_clear flushes the tlb, in radix, we have to
 137         */
 138        pte_clear(&init_mm, addr, ptep);
 139        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 140
 141        return 0;
 142}
 143
 144static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
 145{
 146        int err;
 147        u32 *patch_addr = NULL;
 148        unsigned long flags;
 149        unsigned long text_poke_addr;
 150        unsigned long kaddr = (unsigned long)addr;
 151
 152        /*
 153         * During early early boot patch_instruction is called
 154         * when text_poke_area is not ready, but we still need
 155         * to allow patching. We just do the plain old patching
 156         */
 157        if (!this_cpu_read(text_poke_area))
 158                return raw_patch_instruction(addr, instr);
 159
 160        local_irq_save(flags);
 161
 162        text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 163        if (map_patch_area(addr, text_poke_addr)) {
 164                err = -1;
 165                goto out;
 166        }
 167
 168        patch_addr = (u32 *)(text_poke_addr + (kaddr & ~PAGE_MASK));
 169
 170        __patch_instruction(addr, instr, patch_addr);
 171
 172        err = unmap_patch_area(text_poke_addr);
 173        if (err)
 174                pr_warn("failed to unmap %lx\n", text_poke_addr);
 175
 176out:
 177        local_irq_restore(flags);
 178
 179        return err;
 180}
 181#else /* !CONFIG_STRICT_KERNEL_RWX */
 182
 183static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
 184{
 185        return raw_patch_instruction(addr, instr);
 186}
 187
 188#endif /* CONFIG_STRICT_KERNEL_RWX */
 189
 190int patch_instruction(u32 *addr, struct ppc_inst instr)
 191{
 192        /* Make sure we aren't patching a freed init section */
 193        if (init_mem_is_free && init_section_contains(addr, 4)) {
 194                pr_debug("Skipping init section patching addr: 0x%px\n", addr);
 195                return 0;
 196        }
 197        return do_patch_instruction(addr, instr);
 198}
 199NOKPROBE_SYMBOL(patch_instruction);
 200
 201int patch_branch(u32 *addr, unsigned long target, int flags)
 202{
 203        struct ppc_inst instr;
 204
 205        create_branch(&instr, addr, target, flags);
 206        return patch_instruction(addr, instr);
 207}
 208
 209bool is_offset_in_branch_range(long offset)
 210{
 211        /*
 212         * Powerpc branch instruction is :
 213         *
 214         *  0         6                 30   31
 215         *  +---------+----------------+---+---+
 216         *  | opcode  |     LI         |AA |LK |
 217         *  +---------+----------------+---+---+
 218         *  Where AA = 0 and LK = 0
 219         *
 220         * LI is a signed 24 bits integer. The real branch offset is computed
 221         * by: imm32 = SignExtend(LI:'0b00', 32);
 222         *
 223         * So the maximum forward branch should be:
 224         *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 225         * The maximum backward branch should be:
 226         *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 227         */
 228        return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 229}
 230
 231/*
 232 * Helper to check if a given instruction is a conditional branch
 233 * Derived from the conditional checks in analyse_instr()
 234 */
 235bool is_conditional_branch(struct ppc_inst instr)
 236{
 237        unsigned int opcode = ppc_inst_primary_opcode(instr);
 238
 239        if (opcode == 16)       /* bc, bca, bcl, bcla */
 240                return true;
 241        if (opcode == 19) {
 242                switch ((ppc_inst_val(instr) >> 1) & 0x3ff) {
 243                case 16:        /* bclr, bclrl */
 244                case 528:       /* bcctr, bcctrl */
 245                case 560:       /* bctar, bctarl */
 246                        return true;
 247                }
 248        }
 249        return false;
 250}
 251NOKPROBE_SYMBOL(is_conditional_branch);
 252
 253int create_branch(struct ppc_inst *instr, const u32 *addr,
 254                  unsigned long target, int flags)
 255{
 256        long offset;
 257
 258        *instr = ppc_inst(0);
 259        offset = target;
 260        if (! (flags & BRANCH_ABSOLUTE))
 261                offset = offset - (unsigned long)addr;
 262
 263        /* Check we can represent the target in the instruction format */
 264        if (!is_offset_in_branch_range(offset))
 265                return 1;
 266
 267        /* Mask out the flags and target, so they don't step on each other. */
 268        *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
 269
 270        return 0;
 271}
 272
 273int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
 274                       unsigned long target, int flags)
 275{
 276        long offset;
 277
 278        offset = target;
 279        if (! (flags & BRANCH_ABSOLUTE))
 280                offset = offset - (unsigned long)addr;
 281
 282        /* Check we can represent the target in the instruction format */
 283        if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 284                return 1;
 285
 286        /* Mask out the flags and target, so they don't step on each other. */
 287        *instr = ppc_inst(0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC));
 288
 289        return 0;
 290}
 291
 292static unsigned int branch_opcode(struct ppc_inst instr)
 293{
 294        return ppc_inst_primary_opcode(instr) & 0x3F;
 295}
 296
 297static int instr_is_branch_iform(struct ppc_inst instr)
 298{
 299        return branch_opcode(instr) == 18;
 300}
 301
 302static int instr_is_branch_bform(struct ppc_inst instr)
 303{
 304        return branch_opcode(instr) == 16;
 305}
 306
 307int instr_is_relative_branch(struct ppc_inst instr)
 308{
 309        if (ppc_inst_val(instr) & BRANCH_ABSOLUTE)
 310                return 0;
 311
 312        return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 313}
 314
 315int instr_is_relative_link_branch(struct ppc_inst instr)
 316{
 317        return instr_is_relative_branch(instr) && (ppc_inst_val(instr) & BRANCH_SET_LINK);
 318}
 319
 320static unsigned long branch_iform_target(const u32 *instr)
 321{
 322        signed long imm;
 323
 324        imm = ppc_inst_val(ppc_inst_read(instr)) & 0x3FFFFFC;
 325
 326        /* If the top bit of the immediate value is set this is negative */
 327        if (imm & 0x2000000)
 328                imm -= 0x4000000;
 329
 330        if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0)
 331                imm += (unsigned long)instr;
 332
 333        return (unsigned long)imm;
 334}
 335
 336static unsigned long branch_bform_target(const u32 *instr)
 337{
 338        signed long imm;
 339
 340        imm = ppc_inst_val(ppc_inst_read(instr)) & 0xFFFC;
 341
 342        /* If the top bit of the immediate value is set this is negative */
 343        if (imm & 0x8000)
 344                imm -= 0x10000;
 345
 346        if ((ppc_inst_val(ppc_inst_read(instr)) & BRANCH_ABSOLUTE) == 0)
 347                imm += (unsigned long)instr;
 348
 349        return (unsigned long)imm;
 350}
 351
 352unsigned long branch_target(const u32 *instr)
 353{
 354        if (instr_is_branch_iform(ppc_inst_read(instr)))
 355                return branch_iform_target(instr);
 356        else if (instr_is_branch_bform(ppc_inst_read(instr)))
 357                return branch_bform_target(instr);
 358
 359        return 0;
 360}
 361
 362int translate_branch(struct ppc_inst *instr, const u32 *dest, const u32 *src)
 363{
 364        unsigned long target;
 365        target = branch_target(src);
 366
 367        if (instr_is_branch_iform(ppc_inst_read(src)))
 368                return create_branch(instr, dest, target,
 369                                     ppc_inst_val(ppc_inst_read(src)));
 370        else if (instr_is_branch_bform(ppc_inst_read(src)))
 371                return create_cond_branch(instr, dest, target,
 372                                          ppc_inst_val(ppc_inst_read(src)));
 373
 374        return 1;
 375}
 376
 377#ifdef CONFIG_PPC_BOOK3E_64
 378void __patch_exception(int exc, unsigned long addr)
 379{
 380        extern unsigned int interrupt_base_book3e;
 381        unsigned int *ibase = &interrupt_base_book3e;
 382
 383        /* Our exceptions vectors start with a NOP and -then- a branch
 384         * to deal with single stepping from userspace which stops on
 385         * the second instruction. Thus we need to patch the second
 386         * instruction of the exception, not the first one
 387         */
 388
 389        patch_branch(ibase + (exc / 4) + 1, addr, 0);
 390}
 391#endif
 392
 393#ifdef CONFIG_CODE_PATCHING_SELFTEST
 394
 395static int instr_is_branch_to_addr(const u32 *instr, unsigned long addr)
 396{
 397        if (instr_is_branch_iform(ppc_inst_read(instr)) ||
 398            instr_is_branch_bform(ppc_inst_read(instr)))
 399                return branch_target(instr) == addr;
 400
 401        return 0;
 402}
 403
 404static void __init test_trampoline(void)
 405{
 406        asm ("nop;\n");
 407}
 408
 409#define check(x)        \
 410        if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 411
 412static void __init test_branch_iform(void)
 413{
 414        int err;
 415        struct ppc_inst instr;
 416        u32 tmp[2];
 417        u32 *iptr = tmp;
 418        unsigned long addr = (unsigned long)tmp;
 419
 420        /* The simplest case, branch to self, no flags */
 421        check(instr_is_branch_iform(ppc_inst(0x48000000)));
 422        /* All bits of target set, and flags */
 423        check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
 424        /* High bit of opcode set, which is wrong */
 425        check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
 426        /* Middle bits of opcode set, which is wrong */
 427        check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
 428
 429        /* Simplest case, branch to self with link */
 430        check(instr_is_branch_iform(ppc_inst(0x48000001)));
 431        /* All bits of targets set */
 432        check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
 433        /* Some bits of targets set */
 434        check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
 435        /* Must be a valid branch to start with */
 436        check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
 437
 438        /* Absolute branch to 0x100 */
 439        patch_instruction(iptr, ppc_inst(0x48000103));
 440        check(instr_is_branch_to_addr(iptr, 0x100));
 441        /* Absolute branch to 0x420fc */
 442        patch_instruction(iptr, ppc_inst(0x480420ff));
 443        check(instr_is_branch_to_addr(iptr, 0x420fc));
 444        /* Maximum positive relative branch, + 20MB - 4B */
 445        patch_instruction(iptr, ppc_inst(0x49fffffc));
 446        check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
 447        /* Smallest negative relative branch, - 4B */
 448        patch_instruction(iptr, ppc_inst(0x4bfffffc));
 449        check(instr_is_branch_to_addr(iptr, addr - 4));
 450        /* Largest negative relative branch, - 32 MB */
 451        patch_instruction(iptr, ppc_inst(0x4a000000));
 452        check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
 453
 454        /* Branch to self, with link */
 455        err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
 456        patch_instruction(iptr, instr);
 457        check(instr_is_branch_to_addr(iptr, addr));
 458
 459        /* Branch to self - 0x100, with link */
 460        err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
 461        patch_instruction(iptr, instr);
 462        check(instr_is_branch_to_addr(iptr, addr - 0x100));
 463
 464        /* Branch to self + 0x100, no link */
 465        err = create_branch(&instr, iptr, addr + 0x100, 0);
 466        patch_instruction(iptr, instr);
 467        check(instr_is_branch_to_addr(iptr, addr + 0x100));
 468
 469        /* Maximum relative negative offset, - 32 MB */
 470        err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
 471        patch_instruction(iptr, instr);
 472        check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
 473
 474        /* Out of range relative negative offset, - 32 MB + 4*/
 475        err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
 476        check(err);
 477
 478        /* Out of range relative positive offset, + 32 MB */
 479        err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
 480        check(err);
 481
 482        /* Unaligned target */
 483        err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
 484        check(err);
 485
 486        /* Check flags are masked correctly */
 487        err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
 488        patch_instruction(iptr, instr);
 489        check(instr_is_branch_to_addr(iptr, addr));
 490        check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 491}
 492
 493static void __init test_create_function_call(void)
 494{
 495        u32 *iptr;
 496        unsigned long dest;
 497        struct ppc_inst instr;
 498
 499        /* Check we can create a function call */
 500        iptr = (u32 *)ppc_function_entry(test_trampoline);
 501        dest = ppc_function_entry(test_create_function_call);
 502        create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
 503        patch_instruction(iptr, instr);
 504        check(instr_is_branch_to_addr(iptr, dest));
 505}
 506
 507static void __init test_branch_bform(void)
 508{
 509        int err;
 510        unsigned long addr;
 511        struct ppc_inst instr;
 512        u32 tmp[2];
 513        u32 *iptr = tmp;
 514        unsigned int flags;
 515
 516        addr = (unsigned long)iptr;
 517
 518        /* The simplest case, branch to self, no flags */
 519        check(instr_is_branch_bform(ppc_inst(0x40000000)));
 520        /* All bits of target set, and flags */
 521        check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
 522        /* High bit of opcode set, which is wrong */
 523        check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
 524        /* Middle bits of opcode set, which is wrong */
 525        check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 526
 527        /* Absolute conditional branch to 0x100 */
 528        patch_instruction(iptr, ppc_inst(0x43ff0103));
 529        check(instr_is_branch_to_addr(iptr, 0x100));
 530        /* Absolute conditional branch to 0x20fc */
 531        patch_instruction(iptr, ppc_inst(0x43ff20ff));
 532        check(instr_is_branch_to_addr(iptr, 0x20fc));
 533        /* Maximum positive relative conditional branch, + 32 KB - 4B */
 534        patch_instruction(iptr, ppc_inst(0x43ff7ffc));
 535        check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
 536        /* Smallest negative relative conditional branch, - 4B */
 537        patch_instruction(iptr, ppc_inst(0x43fffffc));
 538        check(instr_is_branch_to_addr(iptr, addr - 4));
 539        /* Largest negative relative conditional branch, - 32 KB */
 540        patch_instruction(iptr, ppc_inst(0x43ff8000));
 541        check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 542
 543        /* All condition code bits set & link */
 544        flags = 0x3ff000 | BRANCH_SET_LINK;
 545
 546        /* Branch to self */
 547        err = create_cond_branch(&instr, iptr, addr, flags);
 548        patch_instruction(iptr, instr);
 549        check(instr_is_branch_to_addr(iptr, addr));
 550
 551        /* Branch to self - 0x100 */
 552        err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
 553        patch_instruction(iptr, instr);
 554        check(instr_is_branch_to_addr(iptr, addr - 0x100));
 555
 556        /* Branch to self + 0x100 */
 557        err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
 558        patch_instruction(iptr, instr);
 559        check(instr_is_branch_to_addr(iptr, addr + 0x100));
 560
 561        /* Maximum relative negative offset, - 32 KB */
 562        err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
 563        patch_instruction(iptr, instr);
 564        check(instr_is_branch_to_addr(iptr, addr - 0x8000));
 565
 566        /* Out of range relative negative offset, - 32 KB + 4*/
 567        err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
 568        check(err);
 569
 570        /* Out of range relative positive offset, + 32 KB */
 571        err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
 572        check(err);
 573
 574        /* Unaligned target */
 575        err = create_cond_branch(&instr, iptr, addr + 3, flags);
 576        check(err);
 577
 578        /* Check flags are masked correctly */
 579        err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
 580        patch_instruction(iptr, instr);
 581        check(instr_is_branch_to_addr(iptr, addr));
 582        check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 583}
 584
 585static void __init test_translate_branch(void)
 586{
 587        unsigned long addr;
 588        void *p, *q;
 589        struct ppc_inst instr;
 590        void *buf;
 591
 592        buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 593        check(buf);
 594        if (!buf)
 595                return;
 596
 597        /* Simple case, branch to self moved a little */
 598        p = buf;
 599        addr = (unsigned long)p;
 600        patch_branch(p, addr, 0);
 601        check(instr_is_branch_to_addr(p, addr));
 602        q = p + 4;
 603        translate_branch(&instr, q, p);
 604        patch_instruction(q, instr);
 605        check(instr_is_branch_to_addr(q, addr));
 606
 607        /* Maximum negative case, move b . to addr + 32 MB */
 608        p = buf;
 609        addr = (unsigned long)p;
 610        patch_branch(p, addr, 0);
 611        q = buf + 0x2000000;
 612        translate_branch(&instr, q, p);
 613        patch_instruction(q, instr);
 614        check(instr_is_branch_to_addr(p, addr));
 615        check(instr_is_branch_to_addr(q, addr));
 616        check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 617
 618        /* Maximum positive case, move x to x - 32 MB + 4 */
 619        p = buf + 0x2000000;
 620        addr = (unsigned long)p;
 621        patch_branch(p, addr, 0);
 622        q = buf + 4;
 623        translate_branch(&instr, q, p);
 624        patch_instruction(q, instr);
 625        check(instr_is_branch_to_addr(p, addr));
 626        check(instr_is_branch_to_addr(q, addr));
 627        check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 628
 629        /* Jump to x + 16 MB moved to x + 20 MB */
 630        p = buf;
 631        addr = 0x1000000 + (unsigned long)buf;
 632        patch_branch(p, addr, BRANCH_SET_LINK);
 633        q = buf + 0x1400000;
 634        translate_branch(&instr, q, p);
 635        patch_instruction(q, instr);
 636        check(instr_is_branch_to_addr(p, addr));
 637        check(instr_is_branch_to_addr(q, addr));
 638
 639        /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 640        p = buf + 0x1000000;
 641        addr = 0x2000000 + (unsigned long)buf;
 642        patch_branch(p, addr, 0);
 643        q = buf + 4;
 644        translate_branch(&instr, q, p);
 645        patch_instruction(q, instr);
 646        check(instr_is_branch_to_addr(p, addr));
 647        check(instr_is_branch_to_addr(q, addr));
 648
 649
 650        /* Conditional branch tests */
 651
 652        /* Simple case, branch to self moved a little */
 653        p = buf;
 654        addr = (unsigned long)p;
 655        create_cond_branch(&instr, p, addr, 0);
 656        patch_instruction(p, instr);
 657        check(instr_is_branch_to_addr(p, addr));
 658        q = buf + 4;
 659        translate_branch(&instr, q, p);
 660        patch_instruction(q, instr);
 661        check(instr_is_branch_to_addr(q, addr));
 662
 663        /* Maximum negative case, move b . to addr + 32 KB */
 664        p = buf;
 665        addr = (unsigned long)p;
 666        create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 667        patch_instruction(p, instr);
 668        q = buf + 0x8000;
 669        translate_branch(&instr, q, p);
 670        patch_instruction(q, instr);
 671        check(instr_is_branch_to_addr(p, addr));
 672        check(instr_is_branch_to_addr(q, addr));
 673        check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 674
 675        /* Maximum positive case, move x to x - 32 KB + 4 */
 676        p = buf + 0x8000;
 677        addr = (unsigned long)p;
 678        create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 679        patch_instruction(p, instr);
 680        q = buf + 4;
 681        translate_branch(&instr, q, p);
 682        patch_instruction(q, instr);
 683        check(instr_is_branch_to_addr(p, addr));
 684        check(instr_is_branch_to_addr(q, addr));
 685        check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 686
 687        /* Jump to x + 12 KB moved to x + 20 KB */
 688        p = buf;
 689        addr = 0x3000 + (unsigned long)buf;
 690        create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
 691        patch_instruction(p, instr);
 692        q = buf + 0x5000;
 693        translate_branch(&instr, q, p);
 694        patch_instruction(q, instr);
 695        check(instr_is_branch_to_addr(p, addr));
 696        check(instr_is_branch_to_addr(q, addr));
 697
 698        /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 699        p = buf + 0x2000;
 700        addr = 0x4000 + (unsigned long)buf;
 701        create_cond_branch(&instr, p, addr, 0);
 702        patch_instruction(p, instr);
 703        q = buf + 4;
 704        translate_branch(&instr, q, p);
 705        patch_instruction(q, instr);
 706        check(instr_is_branch_to_addr(p, addr));
 707        check(instr_is_branch_to_addr(q, addr));
 708
 709        /* Free the buffer we were using */
 710        vfree(buf);
 711}
 712
 713#ifdef CONFIG_PPC64
 714static void __init test_prefixed_patching(void)
 715{
 716        extern unsigned int code_patching_test1[];
 717        extern unsigned int code_patching_test1_expected[];
 718        extern unsigned int end_code_patching_test1[];
 719
 720        __patch_instruction(code_patching_test1,
 721                            ppc_inst_prefix(OP_PREFIX << 26, 0x00000000),
 722                            code_patching_test1);
 723
 724        check(!memcmp(code_patching_test1,
 725                      code_patching_test1_expected,
 726                      sizeof(unsigned int) *
 727                      (end_code_patching_test1 - code_patching_test1)));
 728}
 729#else
 730static inline void test_prefixed_patching(void) {}
 731#endif
 732
 733static int __init test_code_patching(void)
 734{
 735        printk(KERN_DEBUG "Running code patching self-tests ...\n");
 736
 737        test_branch_iform();
 738        test_branch_bform();
 739        test_create_function_call();
 740        test_translate_branch();
 741        test_prefixed_patching();
 742
 743        return 0;
 744}
 745late_initcall(test_code_patching);
 746
 747#endif /* CONFIG_CODE_PATCHING_SELFTEST */
 748