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/tlbflush.h>
  16 #include <asm/page.h>
  17 #include <asm/code-patching.h>
  18 #include <asm/setup.h>
  19 #include <asm/inst.h>
  20
  21 static int __patch_instruction(struct ppc_inst *exec_addr, struct ppc_inst instr,
  22                                struct ppc_inst *patch_addr)
  23 {
  24         int err = 0;
  25
  26         if (!ppc_inst_prefixed(instr)) {
  27                 __put_user_asm(ppc_inst_val(instr), patch_addr, err, "stw");
  28         } else {
  29                 __put_user_asm(ppc_inst_as_u64(instr), patch_addr, err, "std");
  30         }
  31
  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(struct ppc_inst *addr, struct ppc_inst 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), PAGE_KERNEL);
 102
 103         pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
 104         if (err)
 105                 return -1;
 106
 107         return 0;
 108 }
 109
 110 static inline int unmap_patch_area(unsigned long addr)
 111 {
 112         pte_t *ptep;
 113         pmd_t *pmdp;
 114         pud_t *pudp;
 115         p4d_t *p4dp;
 116         pgd_t *pgdp;
 117
 118         pgdp = pgd_offset_k(addr);
 119         if (unlikely(!pgdp))
 120                 return -EINVAL;
 121
 122         p4dp = p4d_offset(pgdp, addr);
 123         if (unlikely(!p4dp))
 124                 return -EINVAL;
 125
 126         pudp = pud_offset(p4dp, addr);
 127         if (unlikely(!pudp))
 128                 return -EINVAL;
 129
 130         pmdp = pmd_offset(pudp, addr);
 131         if (unlikely(!pmdp))
 132                 return -EINVAL;
 133
 134         ptep = pte_offset_kernel(pmdp, addr);
 135         if (unlikely(!ptep))
 136                 return -EINVAL;
 137
 138         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 139
 140         /*
 141          * In hash, pte_clear flushes the tlb, in radix, we have to
 142          */
 143         pte_clear(&init_mm, addr, ptep);
 144         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 145
 146         return 0;
 147 }
 148
 149 static int do_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 150 {
 151         int err;
 152         struct ppc_inst *patch_addr = NULL;
 153         unsigned long flags;
 154         unsigned long text_poke_addr;
 155         unsigned long kaddr = (unsigned long)addr;
 156
 157         /*
 158          * During early early boot patch_instruction is called
 159          * when text_poke_area is not ready, but we still need
 160          * to allow patching. We just do the plain old patching
 161          */
 162         if (!this_cpu_read(text_poke_area))
 163                 return raw_patch_instruction(addr, instr);
 164
 165         local_irq_save(flags);
 166
 167         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 168         if (map_patch_area(addr, text_poke_addr)) {
 169                 err = -1;
 170                 goto out;
 171         }
 172
 173         patch_addr = (struct ppc_inst *)(text_poke_addr + (kaddr & ~PAGE_MASK));
 174
 175         __patch_instruction(addr, instr, patch_addr);
 176
 177         err = unmap_patch_area(text_poke_addr);
 178         if (err)
 179                 pr_warn("failed to unmap %lx\n", text_poke_addr);
 180
 181 out:
 182         local_irq_restore(flags);
 183
 184         return err;
 185 }
 186 #else /* !CONFIG_STRICT_KERNEL_RWX */
 187
 188 static int do_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 189 {
 190         return raw_patch_instruction(addr, instr);
 191 }
 192
 193 #endif /* CONFIG_STRICT_KERNEL_RWX */
 194
 195 int patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 196 {
 197         /* Make sure we aren't patching a freed init section */
 198         if (init_mem_is_free && init_section_contains(addr, 4)) {
 199                 pr_debug("Skipping init section patching addr: 0x%px\n", addr);
 200                 return 0;
 201         }
 202         return do_patch_instruction(addr, instr);
 203 }
 204 NOKPROBE_SYMBOL(patch_instruction);
 205
 206 int patch_branch(struct ppc_inst *addr, unsigned long target, int flags)
 207 {
 208         struct ppc_inst instr;
 209
 210         create_branch(&instr, addr, target, flags);
 211         return patch_instruction(addr, instr);
 212 }
 213
 214 bool is_offset_in_branch_range(long offset)
 215 {
 216         /*
 217          * Powerpc branch instruction is :
 218          *
 219          *  0         6                 30   31
 220          *  +---------+----------------+---+---+
 221          *  | opcode  |     LI         |AA |LK |
 222          *  +---------+----------------+---+---+
 223          *  Where AA = 0 and LK = 0
 224          *
 225          * LI is a signed 24 bits integer. The real branch offset is computed
 226          * by: imm32 = SignExtend(LI:'0b00', 32);
 227          *
 228          * So the maximum forward branch should be:
 229          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 230          * The maximum backward branch should be:
 231          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 232          */
 233         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 234 }
 235
 236 /*
 237  * Helper to check if a given instruction is a conditional branch
 238  * Derived from the conditional checks in analyse_instr()
 239  */
 240 bool is_conditional_branch(struct ppc_inst instr)
 241 {
 242         unsigned int opcode = ppc_inst_primary_opcode(instr);
 243
 244         if (opcode == 16)       /* bc, bca, bcl, bcla */
 245                 return true;
 246         if (opcode == 19) {
 247                 switch ((ppc_inst_val(instr) >> 1) & 0x3ff) {
 248                 case 16:        /* bclr, bclrl */
 249                 case 528:       /* bcctr, bcctrl */
 250                 case 560:       /* bctar, bctarl */
 251                         return true;
 252                 }
 253         }
 254         return false;
 255 }
 256 NOKPROBE_SYMBOL(is_conditional_branch);
 257
 258 int create_branch(struct ppc_inst *instr,
 259                   const struct ppc_inst *addr,
 260                   unsigned long target, int flags)
 261 {
 262         long offset;
 263
 264         *instr = ppc_inst(0);
 265         offset = target;
 266         if (! (flags & BRANCH_ABSOLUTE))
 267                 offset = offset - (unsigned long)addr;
 268
 269         /* Check we can represent the target in the instruction format */
 270         if (!is_offset_in_branch_range(offset))
 271                 return 1;
 272
 273         /* Mask out the flags and target, so they don't step on each other. */
 274         *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
 275
 276         return 0;
 277 }
 278
 279 int create_cond_branch(struct ppc_inst *instr, const struct ppc_inst *addr,
 280                        unsigned long target, int flags)
 281 {
 282         long offset;
 283
 284         offset = target;
 285         if (! (flags & BRANCH_ABSOLUTE))
 286                 offset = offset - (unsigned long)addr;
 287
 288         /* Check we can represent the target in the instruction format */
 289         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 290                 return 1;
 291
 292         /* Mask out the flags and target, so they don't step on each other. */
 293         *instr = ppc_inst(0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC));
 294
 295         return 0;
 296 }
 297
 298 static unsigned int branch_opcode(struct ppc_inst instr)
 299 {
 300         return ppc_inst_primary_opcode(instr) & 0x3F;
 301 }
 302
 303 static int instr_is_branch_iform(struct ppc_inst instr)
 304 {
 305         return branch_opcode(instr) == 18;
 306 }
 307
 308 static int instr_is_branch_bform(struct ppc_inst instr)
 309 {
 310         return branch_opcode(instr) == 16;
 311 }
 312
 313 int instr_is_relative_branch(struct ppc_inst instr)
 314 {
 315         if (ppc_inst_val(instr) & BRANCH_ABSOLUTE)
 316                 return 0;
 317
 318         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 319 }
 320
 321 int instr_is_relative_link_branch(struct ppc_inst instr)
 322 {
 323         return instr_is_relative_branch(instr) && (ppc_inst_val(instr) & BRANCH_SET_LINK);
 324 }
 325
 326 static unsigned long branch_iform_target(const struct ppc_inst *instr)
 327 {
 328         signed long imm;
 329
 330         imm = ppc_inst_val(*instr) & 0x3FFFFFC;
 331
 332         /* If the top bit of the immediate value is set this is negative */
 333         if (imm & 0x2000000)
 334                 imm -= 0x4000000;
 335
 336         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 337                 imm += (unsigned long)instr;
 338
 339         return (unsigned long)imm;
 340 }
 341
 342 static unsigned long branch_bform_target(const struct ppc_inst *instr)
 343 {
 344         signed long imm;
 345
 346         imm = ppc_inst_val(*instr) & 0xFFFC;
 347
 348         /* If the top bit of the immediate value is set this is negative */
 349         if (imm & 0x8000)
 350                 imm -= 0x10000;
 351
 352         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 353                 imm += (unsigned long)instr;
 354
 355         return (unsigned long)imm;
 356 }
 357
 358 unsigned long branch_target(const struct ppc_inst *instr)
 359 {
 360         if (instr_is_branch_iform(ppc_inst_read(instr)))
 361                 return branch_iform_target(instr);
 362         else if (instr_is_branch_bform(ppc_inst_read(instr)))
 363                 return branch_bform_target(instr);
 364
 365         return 0;
 366 }
 367
 368 int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
 369 {
 370         if (instr_is_branch_iform(ppc_inst_read(instr)) ||
 371             instr_is_branch_bform(ppc_inst_read(instr)))
 372                 return branch_target(instr) == addr;
 373
 374         return 0;
 375 }
 376
 377 int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
 378                      const struct ppc_inst *src)
 379 {
 380         unsigned long target;
 381         target = branch_target(src);
 382
 383         if (instr_is_branch_iform(ppc_inst_read(src)))
 384                 return create_branch(instr, dest, target,
 385                                      ppc_inst_val(ppc_inst_read(src)));
 386         else if (instr_is_branch_bform(ppc_inst_read(src)))
 387                 return create_cond_branch(instr, dest, target,
 388                                           ppc_inst_val(ppc_inst_read(src)));
 389
 390         return 1;
 391 }
 392
 393 #ifdef CONFIG_PPC_BOOK3E_64
 394 void __patch_exception(int exc, unsigned long addr)
 395 {
 396         extern unsigned int interrupt_base_book3e;
 397         unsigned int *ibase = &interrupt_base_book3e;
 398
 399         /* Our exceptions vectors start with a NOP and -then- a branch
 400          * to deal with single stepping from userspace which stops on
 401          * the second instruction. Thus we need to patch the second
 402          * instruction of the exception, not the first one
 403          */
 404
 405         patch_branch((struct ppc_inst *)(ibase + (exc / 4) + 1), addr, 0);
 406 }
 407 #endif
 408
 409 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 410
 411 static void __init test_trampoline(void)
 412 {
 413         asm ("nop;\n");
 414 }
 415
 416 #define check(x)        \
 417         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 418
 419 static void __init test_branch_iform(void)
 420 {
 421         int err;
 422         struct ppc_inst instr;
 423         unsigned long addr;
 424
 425         addr = (unsigned long)&instr;
 426
 427         /* The simplest case, branch to self, no flags */
 428         check(instr_is_branch_iform(ppc_inst(0x48000000)));
 429         /* All bits of target set, and flags */
 430         check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
 431         /* High bit of opcode set, which is wrong */
 432         check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
 433         /* Middle bits of opcode set, which is wrong */
 434         check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
 435
 436         /* Simplest case, branch to self with link */
 437         check(instr_is_branch_iform(ppc_inst(0x48000001)));
 438         /* All bits of targets set */
 439         check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
 440         /* Some bits of targets set */
 441         check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
 442         /* Must be a valid branch to start with */
 443         check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
 444
 445         /* Absolute branch to 0x100 */
 446         instr = ppc_inst(0x48000103);
 447         check(instr_is_branch_to_addr(&instr, 0x100));
 448         /* Absolute branch to 0x420fc */
 449         instr = ppc_inst(0x480420ff);
 450         check(instr_is_branch_to_addr(&instr, 0x420fc));
 451         /* Maximum positive relative branch, + 20MB - 4B */
 452         instr = ppc_inst(0x49fffffc);
 453         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 454         /* Smallest negative relative branch, - 4B */
 455         instr = ppc_inst(0x4bfffffc);
 456         check(instr_is_branch_to_addr(&instr, addr - 4));
 457         /* Largest negative relative branch, - 32 MB */
 458         instr = ppc_inst(0x4a000000);
 459         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 460
 461         /* Branch to self, with link */
 462         err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
 463         check(instr_is_branch_to_addr(&instr, addr));
 464
 465         /* Branch to self - 0x100, with link */
 466         err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
 467         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 468
 469         /* Branch to self + 0x100, no link */
 470         err = create_branch(&instr, &instr, addr + 0x100, 0);
 471         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 472
 473         /* Maximum relative negative offset, - 32 MB */
 474         err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
 475         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 476
 477         /* Out of range relative negative offset, - 32 MB + 4*/
 478         err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
 479         check(err);
 480
 481         /* Out of range relative positive offset, + 32 MB */
 482         err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
 483         check(err);
 484
 485         /* Unaligned target */
 486         err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
 487         check(err);
 488
 489         /* Check flags are masked correctly */
 490         err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
 491         check(instr_is_branch_to_addr(&instr, addr));
 492         check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 493 }
 494
 495 static void __init test_create_function_call(void)
 496 {
 497         struct ppc_inst *iptr;
 498         unsigned long dest;
 499         struct ppc_inst instr;
 500
 501         /* Check we can create a function call */
 502         iptr = (struct ppc_inst *)ppc_function_entry(test_trampoline);
 503         dest = ppc_function_entry(test_create_function_call);
 504         create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
 505         patch_instruction(iptr, instr);
 506         check(instr_is_branch_to_addr(iptr, dest));
 507 }
 508
 509 static void __init test_branch_bform(void)
 510 {
 511         int err;
 512         unsigned long addr;
 513         struct ppc_inst *iptr, instr;
 514         unsigned int flags;
 515
 516         iptr = &instr;
 517         addr = (unsigned long)iptr;
 518
 519         /* The simplest case, branch to self, no flags */
 520         check(instr_is_branch_bform(ppc_inst(0x40000000)));
 521         /* All bits of target set, and flags */
 522         check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
 523         /* High bit of opcode set, which is wrong */
 524         check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
 525         /* Middle bits of opcode set, which is wrong */
 526         check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 527
 528         /* Absolute conditional branch to 0x100 */
 529         instr = ppc_inst(0x43ff0103);
 530         check(instr_is_branch_to_addr(&instr, 0x100));
 531         /* Absolute conditional branch to 0x20fc */
 532         instr = ppc_inst(0x43ff20ff);
 533         check(instr_is_branch_to_addr(&instr, 0x20fc));
 534         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 535         instr = ppc_inst(0x43ff7ffc);
 536         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 537         /* Smallest negative relative conditional branch, - 4B */
 538         instr = ppc_inst(0x43fffffc);
 539         check(instr_is_branch_to_addr(&instr, addr - 4));
 540         /* Largest negative relative conditional branch, - 32 KB */
 541         instr = ppc_inst(0x43ff8000);
 542         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 543
 544         /* All condition code bits set & link */
 545         flags = 0x3ff000 | BRANCH_SET_LINK;
 546
 547         /* Branch to self */
 548         err = create_cond_branch(&instr, iptr, addr, flags);
 549         check(instr_is_branch_to_addr(&instr, addr));
 550
 551         /* Branch to self - 0x100 */
 552         err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
 553         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 554
 555         /* Branch to self + 0x100 */
 556         err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
 557         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 558
 559         /* Maximum relative negative offset, - 32 KB */
 560         err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
 561         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 562
 563         /* Out of range relative negative offset, - 32 KB + 4*/
 564         err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
 565         check(err);
 566
 567         /* Out of range relative positive offset, + 32 KB */
 568         err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
 569         check(err);
 570
 571         /* Unaligned target */
 572         err = create_cond_branch(&instr, iptr, addr + 3, flags);
 573         check(err);
 574
 575         /* Check flags are masked correctly */
 576         err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
 577         check(instr_is_branch_to_addr(&instr, addr));
 578         check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 579 }
 580
 581 static void __init test_translate_branch(void)
 582 {
 583         unsigned long addr;
 584         void *p, *q;
 585         struct ppc_inst instr;
 586         void *buf;
 587
 588         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 589         check(buf);
 590         if (!buf)
 591                 return;
 592
 593         /* Simple case, branch to self moved a little */
 594         p = buf;
 595         addr = (unsigned long)p;
 596         patch_branch(p, addr, 0);
 597         check(instr_is_branch_to_addr(p, addr));
 598         q = p + 4;
 599         translate_branch(&instr, q, p);
 600         patch_instruction(q, instr);
 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         translate_branch(&instr, q, p);
 609         patch_instruction(q, instr);
 610         check(instr_is_branch_to_addr(p, addr));
 611         check(instr_is_branch_to_addr(q, addr));
 612         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 613
 614         /* Maximum positive case, move x to x - 32 MB + 4 */
 615         p = buf + 0x2000000;
 616         addr = (unsigned long)p;
 617         patch_branch(p, addr, 0);
 618         q = buf + 4;
 619         translate_branch(&instr, q, p);
 620         patch_instruction(q, instr);
 621         check(instr_is_branch_to_addr(p, addr));
 622         check(instr_is_branch_to_addr(q, addr));
 623         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 624
 625         /* Jump to x + 16 MB moved to x + 20 MB */
 626         p = buf;
 627         addr = 0x1000000 + (unsigned long)buf;
 628         patch_branch(p, addr, BRANCH_SET_LINK);
 629         q = buf + 0x1400000;
 630         translate_branch(&instr, q, p);
 631         patch_instruction(q, instr);
 632         check(instr_is_branch_to_addr(p, addr));
 633         check(instr_is_branch_to_addr(q, addr));
 634
 635         /* Jump to x + 16 MB moved to x - 16 MB + 4 */
 636         p = buf + 0x1000000;
 637         addr = 0x2000000 + (unsigned long)buf;
 638         patch_branch(p, addr, 0);
 639         q = buf + 4;
 640         translate_branch(&instr, q, p);
 641         patch_instruction(q, instr);
 642         check(instr_is_branch_to_addr(p, addr));
 643         check(instr_is_branch_to_addr(q, addr));
 644
 645
 646         /* Conditional branch tests */
 647
 648         /* Simple case, branch to self moved a little */
 649         p = buf;
 650         addr = (unsigned long)p;
 651         create_cond_branch(&instr, p, addr, 0);
 652         patch_instruction(p, instr);
 653         check(instr_is_branch_to_addr(p, addr));
 654         q = buf + 4;
 655         translate_branch(&instr, q, p);
 656         patch_instruction(q, instr);
 657         check(instr_is_branch_to_addr(q, addr));
 658
 659         /* Maximum negative case, move b . to addr + 32 KB */
 660         p = buf;
 661         addr = (unsigned long)p;
 662         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 663         patch_instruction(p, instr);
 664         q = buf + 0x8000;
 665         translate_branch(&instr, q, p);
 666         patch_instruction(q, instr);
 667         check(instr_is_branch_to_addr(p, addr));
 668         check(instr_is_branch_to_addr(q, addr));
 669         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 670
 671         /* Maximum positive case, move x to x - 32 KB + 4 */
 672         p = buf + 0x8000;
 673         addr = (unsigned long)p;
 674         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 675         patch_instruction(p, instr);
 676         q = buf + 4;
 677         translate_branch(&instr, q, p);
 678         patch_instruction(q, instr);
 679         check(instr_is_branch_to_addr(p, addr));
 680         check(instr_is_branch_to_addr(q, addr));
 681         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 682
 683         /* Jump to x + 12 KB moved to x + 20 KB */
 684         p = buf;
 685         addr = 0x3000 + (unsigned long)buf;
 686         create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
 687         patch_instruction(p, instr);
 688         q = buf + 0x5000;
 689         translate_branch(&instr, q, p);
 690         patch_instruction(q, instr);
 691         check(instr_is_branch_to_addr(p, addr));
 692         check(instr_is_branch_to_addr(q, addr));
 693
 694         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 695         p = buf + 0x2000;
 696         addr = 0x4000 + (unsigned long)buf;
 697         create_cond_branch(&instr, p, addr, 0);
 698         patch_instruction(p, instr);
 699         q = buf + 4;
 700         translate_branch(&instr, q, p);
 701         patch_instruction(q, instr);
 702         check(instr_is_branch_to_addr(p, addr));
 703         check(instr_is_branch_to_addr(q, addr));
 704
 705         /* Free the buffer we were using */
 706         vfree(buf);
 707 }
 708
 709 #ifdef CONFIG_PPC64
 710 static void __init test_prefixed_patching(void)
 711 {
 712         extern unsigned int code_patching_test1[];
 713         extern unsigned int code_patching_test1_expected[];
 714         extern unsigned int end_code_patching_test1[];
 715
 716         __patch_instruction((struct ppc_inst *)code_patching_test1,
 717                             ppc_inst_prefix(OP_PREFIX << 26, 0x00000000),
 718                             (struct ppc_inst *)code_patching_test1);
 719
 720         check(!memcmp(code_patching_test1,
 721                       code_patching_test1_expected,
 722                       sizeof(unsigned int) *
 723                       (end_code_patching_test1 - code_patching_test1)));
 724 }
 725 #else
 726 static inline void test_prefixed_patching(void) {}
 727 #endif
 728
 729 static int __init test_code_patching(void)
 730 {
 731         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 732
 733         test_branch_iform();
 734         test_branch_bform();
 735         test_create_function_call();
 736         test_translate_branch();
 737         test_prefixed_patching();
 738
 739         return 0;
 740 }
 741 late_initcall(test_code_patching);
 742
 743 #endif /* CONFIG_CODE_PATCHING_SELFTEST */