arch/powerpc/lib/code-patching.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright 2008 Michael Ellerman, IBM Corporation.
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/kprobes.h>
   8 #include <linux/vmalloc.h>
   9 #include <linux/init.h>
  10 #include <linux/mm.h>
  11 #include <linux/cpuhotplug.h>
  12 #include <linux/slab.h>
  13 #include <linux/uaccess.h>
  14
  15 #include <asm/pgtable.h>
  16 #include <asm/tlbflush.h>
  17 #include <asm/page.h>
  18 #include <asm/code-patching.h>
  19 #include <asm/setup.h>
  20 #include <asm/inst.h>
  21
  22 static int __patch_instruction(struct ppc_inst *exec_addr, struct ppc_inst instr,
  23                                struct ppc_inst *patch_addr)
  24 {
  25         int err = 0;
  26
  27         if (!ppc_inst_prefixed(instr)) {
  28                 __put_user_asm(ppc_inst_val(instr), patch_addr, err, "stw");
  29         } else {
  30                 __put_user_asm(ppc_inst_as_u64(instr), patch_addr, err, "std");
  31         }
  32
  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(struct ppc_inst *addr, struct ppc_inst 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), 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         p4d_t *p4dp;
 117         pgd_t *pgdp;
 118
 119         pgdp = pgd_offset_k(addr);
 120         if (unlikely(!pgdp))
 121                 return -EINVAL;
 122
 123         p4dp = p4d_offset(pgdp, addr);
 124         if (unlikely(!p4dp))
 125                 return -EINVAL;
 126
 127         pudp = pud_offset(p4dp, addr);
 128         if (unlikely(!pudp))
 129                 return -EINVAL;
 130
 131         pmdp = pmd_offset(pudp, addr);
 132         if (unlikely(!pmdp))
 133                 return -EINVAL;
 134
 135         ptep = pte_offset_kernel(pmdp, addr);
 136         if (unlikely(!ptep))
 137                 return -EINVAL;
 138
 139         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 140
 141         /*
 142          * In hash, pte_clear flushes the tlb, in radix, we have to
 143          */
 144         pte_clear(&init_mm, addr, ptep);
 145         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 146
 147         return 0;
 148 }
 149
 150 static int do_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 151 {
 152         int err;
 153         struct ppc_inst *patch_addr = NULL;
 154         unsigned long flags;
 155         unsigned long text_poke_addr;
 156         unsigned long kaddr = (unsigned long)addr;
 157
 158         /*
 159          * During early early boot patch_instruction is called
 160          * when text_poke_area is not ready, but we still need
 161          * to allow patching. We just do the plain old patching
 162          */
 163         if (!this_cpu_read(text_poke_area))
 164                 return raw_patch_instruction(addr, instr);
 165
 166         local_irq_save(flags);
 167
 168         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 169         if (map_patch_area(addr, text_poke_addr)) {
 170                 err = -1;
 171                 goto out;
 172         }
 173
 174         patch_addr = (struct ppc_inst *)(text_poke_addr + (kaddr & ~PAGE_MASK));
 175
 176         __patch_instruction(addr, instr, patch_addr);
 177
 178         err = unmap_patch_area(text_poke_addr);
 179         if (err)
 180                 pr_warn("failed to unmap %lx\n", text_poke_addr);
 181
 182 out:
 183         local_irq_restore(flags);
 184
 185         return err;
 186 }
 187 #else /* !CONFIG_STRICT_KERNEL_RWX */
 188
 189 static int do_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 190 {
 191         return raw_patch_instruction(addr, instr);
 192 }
 193
 194 #endif /* CONFIG_STRICT_KERNEL_RWX */
 195
 196 int patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 197 {
 198         /* Make sure we aren't patching a freed init section */
 199         if (init_mem_is_free && init_section_contains(addr, 4)) {
 200                 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
 201                 return 0;
 202         }
 203         return do_patch_instruction(addr, instr);
 204 }
 205 NOKPROBE_SYMBOL(patch_instruction);
 206
 207 int patch_branch(struct ppc_inst *addr, unsigned long target, int flags)
 208 {
 209         struct ppc_inst instr;
 210
 211         create_branch(&instr, addr, target, flags);
 212         return patch_instruction(addr, instr);
 213 }
 214
 215 bool is_offset_in_branch_range(long offset)
 216 {
 217         /*
 218          * Powerpc branch instruction is :
 219          *
 220          *  0         6                 30   31
 221          *  +---------+----------------+---+---+
 222          *  | opcode  |     LI         |AA |LK |
 223          *  +---------+----------------+---+---+
 224          *  Where AA = 0 and LK = 0
 225          *
 226          * LI is a signed 24 bits integer. The real branch offset is computed
 227          * by: imm32 = SignExtend(LI:'0b00', 32);
 228          *
 229          * So the maximum forward branch should be:
 230          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 231          * The maximum backward branch should be:
 232          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 233          */
 234         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 235 }
 236
 237 /*
 238  * Helper to check if a given instruction is a conditional branch
 239  * Derived from the conditional checks in analyse_instr()
 240  */
 241 bool is_conditional_branch(struct ppc_inst instr)
 242 {
 243         unsigned int opcode = ppc_inst_primary_opcode(instr);
 244
 245         if (opcode == 16)       /* bc, bca, bcl, bcla */
 246                 return true;
 247         if (opcode == 19) {
 248                 switch ((ppc_inst_val(instr) >> 1) & 0x3ff) {
 249                 case 16:        /* bclr, bclrl */
 250                 case 528:       /* bcctr, bcctrl */
 251                 case 560:       /* bctar, bctarl */
 252                         return true;
 253                 }
 254         }
 255         return false;
 256 }
 257 NOKPROBE_SYMBOL(is_conditional_branch);
 258
 259 int create_branch(struct ppc_inst *instr,
 260                   const struct ppc_inst *addr,
 261                   unsigned long target, int flags)
 262 {
 263         long offset;
 264
 265         *instr = ppc_inst(0);
 266         offset = target;
 267         if (! (flags & BRANCH_ABSOLUTE))
 268                 offset = offset - (unsigned long)addr;
 269
 270         /* Check we can represent the target in the instruction format */
 271         if (!is_offset_in_branch_range(offset))
 272                 return 1;
 273
 274         /* Mask out the flags and target, so they don't step on each other. */
 275         *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
 276
 277         return 0;
 278 }
 279
 280 int create_cond_branch(struct ppc_inst *instr, const struct ppc_inst *addr,
 281                        unsigned long target, int flags)
 282 {
 283         long offset;
 284
 285         offset = target;
 286         if (! (flags & BRANCH_ABSOLUTE))
 287                 offset = offset - (unsigned long)addr;
 288
 289         /* Check we can represent the target in the instruction format */
 290         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 291                 return 1;
 292
 293         /* Mask out the flags and target, so they don't step on each other. */
 294         *instr = ppc_inst(0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC));
 295
 296         return 0;
 297 }
 298
 299 static unsigned int branch_opcode(struct ppc_inst instr)
 300 {
 301         return ppc_inst_primary_opcode(instr) & 0x3F;
 302 }
 303
 304 static int instr_is_branch_iform(struct ppc_inst instr)
 305 {
 306         return branch_opcode(instr) == 18;
 307 }
 308
 309 static int instr_is_branch_bform(struct ppc_inst instr)
 310 {
 311         return branch_opcode(instr) == 16;
 312 }
 313
 314 int instr_is_relative_branch(struct ppc_inst instr)
 315 {
 316         if (ppc_inst_val(instr) & BRANCH_ABSOLUTE)
 317                 return 0;
 318
 319         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 320 }
 321
 322 int instr_is_relative_link_branch(struct ppc_inst instr)
 323 {
 324         return instr_is_relative_branch(instr) && (ppc_inst_val(instr) & BRANCH_SET_LINK);
 325 }
 326
 327 static unsigned long branch_iform_target(const struct ppc_inst *instr)
 328 {
 329         signed long imm;
 330
 331         imm = ppc_inst_val(*instr) & 0x3FFFFFC;
 332
 333         /* If the top bit of the immediate value is set this is negative */
 334         if (imm & 0x2000000)
 335                 imm -= 0x4000000;
 336
 337         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 338                 imm += (unsigned long)instr;
 339
 340         return (unsigned long)imm;
 341 }
 342
 343 static unsigned long branch_bform_target(const struct ppc_inst *instr)
 344 {
 345         signed long imm;
 346
 347         imm = ppc_inst_val(*instr) & 0xFFFC;
 348
 349         /* If the top bit of the immediate value is set this is negative */
 350         if (imm & 0x8000)
 351                 imm -= 0x10000;
 352
 353         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 354                 imm += (unsigned long)instr;
 355
 356         return (unsigned long)imm;
 357 }
 358
 359 unsigned long branch_target(const struct ppc_inst *instr)
 360 {
 361         if (instr_is_branch_iform(ppc_inst_read(instr)))
 362                 return branch_iform_target(instr);
 363         else if (instr_is_branch_bform(ppc_inst_read(instr)))
 364                 return branch_bform_target(instr);
 365
 366         return 0;
 367 }
 368
 369 int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
 370 {
 371         if (instr_is_branch_iform(ppc_inst_read(instr)) ||
 372             instr_is_branch_bform(ppc_inst_read(instr)))
 373                 return branch_target(instr) == addr;
 374
 375         return 0;
 376 }
 377
 378 int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
 379                      const struct ppc_inst *src)
 380 {
 381         unsigned long target;
 382         target = branch_target(src);
 383
 384         if (instr_is_branch_iform(ppc_inst_read(src)))
 385                 return create_branch(instr, dest, target,
 386                                      ppc_inst_val(ppc_inst_read(src)));
 387         else if (instr_is_branch_bform(ppc_inst_read(src)))
 388                 return create_cond_branch(instr, dest, target,
 389                                           ppc_inst_val(ppc_inst_read(src)));
 390
 391         return 1;
 392 }
 393
 394 #ifdef CONFIG_PPC_BOOK3E_64
 395 void __patch_exception(int exc, unsigned long addr)
 396 {
 397         extern unsigned int interrupt_base_book3e;
 398         unsigned int *ibase = &interrupt_base_book3e;
 399
 400         /* Our exceptions vectors start with a NOP and -then- a branch
 401          * to deal with single stepping from userspace which stops on
 402          * the second instruction. Thus we need to patch the second
 403          * instruction of the exception, not the first one
 404          */
 405
 406         patch_branch((struct ppc_inst *)(ibase + (exc / 4) + 1), addr, 0);
 407 }
 408 #endif
 409
 410 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 411
 412 static void __init test_trampoline(void)
 413 {
 414         asm ("nop;\n");
 415 }
 416
 417 #define check(x)        \
 418         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 419
 420 static void __init test_branch_iform(void)
 421 {
 422         int err;
 423         struct ppc_inst instr;
 424         unsigned long addr;
 425
 426         addr = (unsigned long)&instr;
 427
 428         /* The simplest case, branch to self, no flags */
 429         check(instr_is_branch_iform(ppc_inst(0x48000000)));
 430         /* All bits of target set, and flags */
 431         check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
 432         /* High bit of opcode set, which is wrong */
 433         check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
 434         /* Middle bits of opcode set, which is wrong */
 435         check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
 436
 437         /* Simplest case, branch to self with link */
 438         check(instr_is_branch_iform(ppc_inst(0x48000001)));
 439         /* All bits of targets set */
 440         check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
 441         /* Some bits of targets set */
 442         check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
 443         /* Must be a valid branch to start with */
 444         check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
 445
 446         /* Absolute branch to 0x100 */
 447         instr = ppc_inst(0x48000103);
 448         check(instr_is_branch_to_addr(&instr, 0x100));
 449         /* Absolute branch to 0x420fc */
 450         instr = ppc_inst(0x480420ff);
 451         check(instr_is_branch_to_addr(&instr, 0x420fc));
 452         /* Maximum positive relative branch, + 20MB - 4B */
 453         instr = ppc_inst(0x49fffffc);
 454         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 455         /* Smallest negative relative branch, - 4B */
 456         instr = ppc_inst(0x4bfffffc);
 457         check(instr_is_branch_to_addr(&instr, addr - 4));
 458         /* Largest negative relative branch, - 32 MB */
 459         instr = ppc_inst(0x4a000000);
 460         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 461
 462         /* Branch to self, with link */
 463         err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
 464         check(instr_is_branch_to_addr(&instr, addr));
 465
 466         /* Branch to self - 0x100, with link */
 467         err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
 468         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 469
 470         /* Branch to self + 0x100, no link */
 471         err = create_branch(&instr, &instr, addr + 0x100, 0);
 472         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 473
 474         /* Maximum relative negative offset, - 32 MB */
 475         err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
 476         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 477
 478         /* Out of range relative negative offset, - 32 MB + 4*/
 479         err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
 480         check(err);
 481
 482         /* Out of range relative positive offset, + 32 MB */
 483         err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
 484         check(err);
 485
 486         /* Unaligned target */
 487         err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
 488         check(err);
 489
 490         /* Check flags are masked correctly */
 491         err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
 492         check(instr_is_branch_to_addr(&instr, addr));
 493         check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 494 }
 495
 496 static void __init test_create_function_call(void)
 497 {
 498         struct ppc_inst *iptr;
 499         unsigned long dest;
 500         struct ppc_inst instr;
 501
 502         /* Check we can create a function call */
 503         iptr = (struct ppc_inst *)ppc_function_entry(test_trampoline);
 504         dest = ppc_function_entry(test_create_function_call);
 505         create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
 506         patch_instruction(iptr, instr);
 507         check(instr_is_branch_to_addr(iptr, dest));
 508 }
 509
 510 static void __init test_branch_bform(void)
 511 {
 512         int err;
 513         unsigned long addr;
 514         struct ppc_inst *iptr, instr;
 515         unsigned int flags;
 516
 517         iptr = &instr;
 518         addr = (unsigned long)iptr;
 519
 520         /* The simplest case, branch to self, no flags */
 521         check(instr_is_branch_bform(ppc_inst(0x40000000)));
 522         /* All bits of target set, and flags */
 523         check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
 524         /* High bit of opcode set, which is wrong */
 525         check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
 526         /* Middle bits of opcode set, which is wrong */
 527         check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 528
 529         /* Absolute conditional branch to 0x100 */
 530         instr = ppc_inst(0x43ff0103);
 531         check(instr_is_branch_to_addr(&instr, 0x100));
 532         /* Absolute conditional branch to 0x20fc */
 533         instr = ppc_inst(0x43ff20ff);
 534         check(instr_is_branch_to_addr(&instr, 0x20fc));
 535         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 536         instr = ppc_inst(0x43ff7ffc);
 537         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 538         /* Smallest negative relative conditional branch, - 4B */
 539         instr = ppc_inst(0x43fffffc);
 540         check(instr_is_branch_to_addr(&instr, addr - 4));
 541         /* Largest negative relative conditional branch, - 32 KB */
 542         instr = ppc_inst(0x43ff8000);
 543         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 544
 545         /* All condition code bits set & link */
 546         flags = 0x3ff000 | BRANCH_SET_LINK;
 547
 548         /* Branch to self */
 549         err = create_cond_branch(&instr, iptr, addr, flags);
 550         check(instr_is_branch_to_addr(&instr, addr));
 551
 552         /* Branch to self - 0x100 */
 553         err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
 554         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 555
 556         /* Branch to self + 0x100 */
 557         err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
 558         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 559
 560         /* Maximum relative negative offset, - 32 KB */
 561         err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
 562         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 563
 564         /* Out of range relative negative offset, - 32 KB + 4*/
 565         err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
 566         check(err);
 567
 568         /* Out of range relative positive offset, + 32 KB */
 569         err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
 570         check(err);
 571
 572         /* Unaligned target */
 573         err = create_cond_branch(&instr, iptr, addr + 3, flags);
 574         check(err);
 575
 576         /* Check flags are masked correctly */
 577         err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
 578         check(instr_is_branch_to_addr(&instr, addr));
 579         check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 580 }
 581
 582 static void __init test_translate_branch(void)
 583 {
 584         unsigned long addr;
 585         void *p, *q;
 586         struct ppc_inst instr;
 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 + 4;
 600         translate_branch(&instr, q, p);
 601         patch_instruction(q, instr);
 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         translate_branch(&instr, q, p);
 610         patch_instruction(q, instr);
 611         check(instr_is_branch_to_addr(p, addr));
 612         check(instr_is_branch_to_addr(q, addr));
 613         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 614
 615         /* Maximum positive case, move x to x - 32 MB + 4 */
 616         p = buf + 0x2000000;
 617         addr = (unsigned long)p;
 618         patch_branch(p, addr, 0);
 619         q = buf + 4;
 620         translate_branch(&instr, q, p);
 621         patch_instruction(q, instr);
 622         check(instr_is_branch_to_addr(p, addr));
 623         check(instr_is_branch_to_addr(q, addr));
 624         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 625
 626         /* Jump to x + 16 MB moved to x + 20 MB */
 627         p = buf;
 628         addr = 0x1000000 + (unsigned long)buf;
 629         patch_branch(p, addr, BRANCH_SET_LINK);
 630         q = buf + 0x1400000;
 631         translate_branch(&instr, q, p);
 632         patch_instruction(q, instr);
 633         check(instr_is_branch_to_addr(p, addr));
 634         check(instr_is_branch_to_addr(q, addr));
 635
 636         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 637         p = buf + 0x1000000;
 638         addr = 0x2000000 + (unsigned long)buf;
 639         patch_branch(p, addr, 0);
 640         q = buf + 4;
 641         translate_branch(&instr, q, p);
 642         patch_instruction(q, instr);
 643         check(instr_is_branch_to_addr(p, addr));
 644         check(instr_is_branch_to_addr(q, addr));
 645
 646
 647         /* Conditional branch tests */
 648
 649         /* Simple case, branch to self moved a little */
 650         p = buf;
 651         addr = (unsigned long)p;
 652         create_cond_branch(&instr, p, addr, 0);
 653         patch_instruction(p, instr);
 654         check(instr_is_branch_to_addr(p, addr));
 655         q = buf + 4;
 656         translate_branch(&instr, q, p);
 657         patch_instruction(q, instr);
 658         check(instr_is_branch_to_addr(q, addr));
 659
 660         /* Maximum negative case, move b . to addr + 32 KB */
 661         p = buf;
 662         addr = (unsigned long)p;
 663         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 664         patch_instruction(p, instr);
 665         q = buf + 0x8000;
 666         translate_branch(&instr, q, p);
 667         patch_instruction(q, instr);
 668         check(instr_is_branch_to_addr(p, addr));
 669         check(instr_is_branch_to_addr(q, addr));
 670         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 671
 672         /* Maximum positive case, move x to x - 32 KB + 4 */
 673         p = buf + 0x8000;
 674         addr = (unsigned long)p;
 675         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 676         patch_instruction(p, instr);
 677         q = buf + 4;
 678         translate_branch(&instr, q, p);
 679         patch_instruction(q, instr);
 680         check(instr_is_branch_to_addr(p, addr));
 681         check(instr_is_branch_to_addr(q, addr));
 682         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 683
 684         /* Jump to x + 12 KB moved to x + 20 KB */
 685         p = buf;
 686         addr = 0x3000 + (unsigned long)buf;
 687         create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
 688         patch_instruction(p, instr);
 689         q = buf + 0x5000;
 690         translate_branch(&instr, q, p);
 691         patch_instruction(q, instr);
 692         check(instr_is_branch_to_addr(p, addr));
 693         check(instr_is_branch_to_addr(q, addr));
 694
 695         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 696         p = buf + 0x2000;
 697         addr = 0x4000 + (unsigned long)buf;
 698         create_cond_branch(&instr, p, addr, 0);
 699         patch_instruction(p, instr);
 700         q = buf + 4;
 701         translate_branch(&instr, q, p);
 702         patch_instruction(q, instr);
 703         check(instr_is_branch_to_addr(p, addr));
 704         check(instr_is_branch_to_addr(q, addr));
 705
 706         /* Free the buffer we were using */
 707         vfree(buf);
 708 }
 709
 710 #ifdef CONFIG_PPC64
 711 static void __init test_prefixed_patching(void)
 712 {
 713         extern unsigned int code_patching_test1[];
 714         extern unsigned int code_patching_test1_expected[];
 715         extern unsigned int end_code_patching_test1[];
 716
 717         __patch_instruction((struct ppc_inst *)code_patching_test1,
 718                             ppc_inst_prefix(OP_PREFIX << 26, 0x00000000),
 719                             (struct ppc_inst *)code_patching_test1);
 720
 721         check(!memcmp(code_patching_test1,
 722                       code_patching_test1_expected,
 723                       sizeof(unsigned int) *
 724                       (end_code_patching_test1 - code_patching_test1)));
 725 }
 726 #else
 727 static inline void test_prefixed_patching(void) {}
 728 #endif
 729
 730 static int __init test_code_patching(void)
 731 {
 732         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 733
 734         test_branch_iform();
 735         test_branch_bform();
 736         test_create_function_call();
 737         test_translate_branch();
 738         test_prefixed_patching();
 739
 740         return 0;
 741 }
 742 late_initcall(test_code_patching);
 743
 744 #endif /* CONFIG_CODE_PATCHING_SELFTEST */