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         if (!ppc_inst_prefixed(instr))
  25                 __put_user_asm_goto(ppc_inst_val(instr), patch_addr, failed, "stw");
  26         else
  27                 __put_user_asm_goto(ppc_inst_as_u64(instr), patch_addr, failed, "std");
  28
  29         asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
  30                                                             "r" (exec_addr));
  31
  32         return 0;
  33
  34 failed:
  35         return -EFAULT;
  36 }
  37
  38 int raw_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
  39 {
  40         return __patch_instruction(addr, instr, addr);
  41 }
  42
  43 #ifdef CONFIG_STRICT_KERNEL_RWX
  44 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
  45
  46 static int text_area_cpu_up(unsigned int cpu)
  47 {
  48         struct vm_struct *area;
  49
  50         area = get_vm_area(PAGE_SIZE, VM_ALLOC);
  51         if (!area) {
  52                 WARN_ONCE(1, "Failed to create text area for cpu %d\n",
  53                         cpu);
  54                 return -1;
  55         }
  56         this_cpu_write(text_poke_area, area);
  57
  58         return 0;
  59 }
  60
  61 static int text_area_cpu_down(unsigned int cpu)
  62 {
  63         free_vm_area(this_cpu_read(text_poke_area));
  64         return 0;
  65 }
  66
  67 /*
  68  * Run as a late init call. This allows all the boot time patching to be done
  69  * simply by patching the code, and then we're called here prior to
  70  * mark_rodata_ro(), which happens after all init calls are run. Although
  71  * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge
  72  * it as being preferable to a kernel that will crash later when someone tries
  73  * to use patch_instruction().
  74  */
  75 static int __init setup_text_poke_area(void)
  76 {
  77         BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
  78                 "powerpc/text_poke:online", text_area_cpu_up,
  79                 text_area_cpu_down));
  80
  81         return 0;
  82 }
  83 late_initcall(setup_text_poke_area);
  84
  85 /*
  86  * This can be called for kernel text or a module.
  87  */
  88 static int map_patch_area(void *addr, unsigned long text_poke_addr)
  89 {
  90         unsigned long pfn;
  91         int err;
  92
  93         if (is_vmalloc_or_module_addr(addr))
  94                 pfn = vmalloc_to_pfn(addr);
  95         else
  96                 pfn = __pa_symbol(addr) >> PAGE_SHIFT;
  97
  98         err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
  99
 100         pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
 101         if (err)
 102                 return -1;
 103
 104         return 0;
 105 }
 106
 107 static inline int unmap_patch_area(unsigned long addr)
 108 {
 109         pte_t *ptep;
 110         pmd_t *pmdp;
 111         pud_t *pudp;
 112         p4d_t *p4dp;
 113         pgd_t *pgdp;
 114
 115         pgdp = pgd_offset_k(addr);
 116         if (unlikely(!pgdp))
 117                 return -EINVAL;
 118
 119         p4dp = p4d_offset(pgdp, addr);
 120         if (unlikely(!p4dp))
 121                 return -EINVAL;
 122
 123         pudp = pud_offset(p4dp, addr);
 124         if (unlikely(!pudp))
 125                 return -EINVAL;
 126
 127         pmdp = pmd_offset(pudp, addr);
 128         if (unlikely(!pmdp))
 129                 return -EINVAL;
 130
 131         ptep = pte_offset_kernel(pmdp, addr);
 132         if (unlikely(!ptep))
 133                 return -EINVAL;
 134
 135         pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
 136
 137         /*
 138          * In hash, pte_clear flushes the tlb, in radix, we have to
 139          */
 140         pte_clear(&init_mm, addr, ptep);
 141         flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
 142
 143         return 0;
 144 }
 145
 146 static int do_patch_instruction(struct ppc_inst *addr, struct ppc_inst instr)
 147 {
 148         int err;
 149         struct ppc_inst *patch_addr = NULL;
 150         unsigned long flags;
 151         unsigned long text_poke_addr;
 152         unsigned long kaddr = (unsigned long)addr;
 153
 154         /*
 155          * During early early boot patch_instruction is called
 156          * when text_poke_area is not ready, but we still need
 157          * to allow patching. We just do the plain old patching
 158          */
 159         if (!this_cpu_read(text_poke_area))
 160                 return raw_patch_instruction(addr, instr);
 161
 162         local_irq_save(flags);
 163
 164         text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
 165         if (map_patch_area(addr, text_poke_addr)) {
 166                 err = -1;
 167                 goto out;
 168         }
 169
 170         patch_addr = (struct ppc_inst *)(text_poke_addr + (kaddr & ~PAGE_MASK));
 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(struct ppc_inst *addr, struct ppc_inst instr)
 186 {
 187         return raw_patch_instruction(addr, instr);
 188 }
 189
 190 #endif /* CONFIG_STRICT_KERNEL_RWX */
 191
 192 int patch_instruction(struct ppc_inst *addr, struct ppc_inst 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(struct ppc_inst *addr, unsigned long target, int flags)
 204 {
 205         struct ppc_inst instr;
 206
 207         create_branch(&instr, addr, target, flags);
 208         return patch_instruction(addr, instr);
 209 }
 210
 211 bool is_offset_in_branch_range(long offset)
 212 {
 213         /*
 214          * Powerpc branch instruction is :
 215          *
 216          *  0         6                 30   31
 217          *  +---------+----------------+---+---+
 218          *  | opcode  |     LI         |AA |LK |
 219          *  +---------+----------------+---+---+
 220          *  Where AA = 0 and LK = 0
 221          *
 222          * LI is a signed 24 bits integer. The real branch offset is computed
 223          * by: imm32 = SignExtend(LI:'0b00', 32);
 224          *
 225          * So the maximum forward branch should be:
 226          *   (0x007fffff << 2) = 0x01fffffc =  0x1fffffc
 227          * The maximum backward branch should be:
 228          *   (0xff800000 << 2) = 0xfe000000 = -0x2000000
 229          */
 230         return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
 231 }
 232
 233 /*
 234  * Helper to check if a given instruction is a conditional branch
 235  * Derived from the conditional checks in analyse_instr()
 236  */
 237 bool is_conditional_branch(struct ppc_inst instr)
 238 {
 239         unsigned int opcode = ppc_inst_primary_opcode(instr);
 240
 241         if (opcode == 16)       /* bc, bca, bcl, bcla */
 242                 return true;
 243         if (opcode == 19) {
 244                 switch ((ppc_inst_val(instr) >> 1) & 0x3ff) {
 245                 case 16:        /* bclr, bclrl */
 246                 case 528:       /* bcctr, bcctrl */
 247                 case 560:       /* bctar, bctarl */
 248                         return true;
 249                 }
 250         }
 251         return false;
 252 }
 253 NOKPROBE_SYMBOL(is_conditional_branch);
 254
 255 int create_branch(struct ppc_inst *instr,
 256                   const struct ppc_inst *addr,
 257                   unsigned long target, int flags)
 258 {
 259         long offset;
 260
 261         *instr = ppc_inst(0);
 262         offset = target;
 263         if (! (flags & BRANCH_ABSOLUTE))
 264                 offset = offset - (unsigned long)addr;
 265
 266         /* Check we can represent the target in the instruction format */
 267         if (!is_offset_in_branch_range(offset))
 268                 return 1;
 269
 270         /* Mask out the flags and target, so they don't step on each other. */
 271         *instr = ppc_inst(0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC));
 272
 273         return 0;
 274 }
 275
 276 int create_cond_branch(struct ppc_inst *instr, const struct ppc_inst *addr,
 277                        unsigned long target, int flags)
 278 {
 279         long offset;
 280
 281         offset = target;
 282         if (! (flags & BRANCH_ABSOLUTE))
 283                 offset = offset - (unsigned long)addr;
 284
 285         /* Check we can represent the target in the instruction format */
 286         if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
 287                 return 1;
 288
 289         /* Mask out the flags and target, so they don't step on each other. */
 290         *instr = ppc_inst(0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC));
 291
 292         return 0;
 293 }
 294
 295 static unsigned int branch_opcode(struct ppc_inst instr)
 296 {
 297         return ppc_inst_primary_opcode(instr) & 0x3F;
 298 }
 299
 300 static int instr_is_branch_iform(struct ppc_inst instr)
 301 {
 302         return branch_opcode(instr) == 18;
 303 }
 304
 305 static int instr_is_branch_bform(struct ppc_inst instr)
 306 {
 307         return branch_opcode(instr) == 16;
 308 }
 309
 310 int instr_is_relative_branch(struct ppc_inst instr)
 311 {
 312         if (ppc_inst_val(instr) & BRANCH_ABSOLUTE)
 313                 return 0;
 314
 315         return instr_is_branch_iform(instr) || instr_is_branch_bform(instr);
 316 }
 317
 318 int instr_is_relative_link_branch(struct ppc_inst instr)
 319 {
 320         return instr_is_relative_branch(instr) && (ppc_inst_val(instr) & BRANCH_SET_LINK);
 321 }
 322
 323 static unsigned long branch_iform_target(const struct ppc_inst *instr)
 324 {
 325         signed long imm;
 326
 327         imm = ppc_inst_val(*instr) & 0x3FFFFFC;
 328
 329         /* If the top bit of the immediate value is set this is negative */
 330         if (imm & 0x2000000)
 331                 imm -= 0x4000000;
 332
 333         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 334                 imm += (unsigned long)instr;
 335
 336         return (unsigned long)imm;
 337 }
 338
 339 static unsigned long branch_bform_target(const struct ppc_inst *instr)
 340 {
 341         signed long imm;
 342
 343         imm = ppc_inst_val(*instr) & 0xFFFC;
 344
 345         /* If the top bit of the immediate value is set this is negative */
 346         if (imm & 0x8000)
 347                 imm -= 0x10000;
 348
 349         if ((ppc_inst_val(*instr) & BRANCH_ABSOLUTE) == 0)
 350                 imm += (unsigned long)instr;
 351
 352         return (unsigned long)imm;
 353 }
 354
 355 unsigned long branch_target(const struct ppc_inst *instr)
 356 {
 357         if (instr_is_branch_iform(ppc_inst_read(instr)))
 358                 return branch_iform_target(instr);
 359         else if (instr_is_branch_bform(ppc_inst_read(instr)))
 360                 return branch_bform_target(instr);
 361
 362         return 0;
 363 }
 364
 365 int instr_is_branch_to_addr(const struct ppc_inst *instr, unsigned long addr)
 366 {
 367         if (instr_is_branch_iform(ppc_inst_read(instr)) ||
 368             instr_is_branch_bform(ppc_inst_read(instr)))
 369                 return branch_target(instr) == addr;
 370
 371         return 0;
 372 }
 373
 374 int translate_branch(struct ppc_inst *instr, const struct ppc_inst *dest,
 375                      const struct ppc_inst *src)
 376 {
 377         unsigned long target;
 378         target = branch_target(src);
 379
 380         if (instr_is_branch_iform(ppc_inst_read(src)))
 381                 return create_branch(instr, dest, target,
 382                                      ppc_inst_val(ppc_inst_read(src)));
 383         else if (instr_is_branch_bform(ppc_inst_read(src)))
 384                 return create_cond_branch(instr, dest, target,
 385                                           ppc_inst_val(ppc_inst_read(src)));
 386
 387         return 1;
 388 }
 389
 390 #ifdef CONFIG_PPC_BOOK3E_64
 391 void __patch_exception(int exc, unsigned long addr)
 392 {
 393         extern unsigned int interrupt_base_book3e;
 394         unsigned int *ibase = &interrupt_base_book3e;
 395
 396         /* Our exceptions vectors start with a NOP and -then- a branch
 397          * to deal with single stepping from userspace which stops on
 398          * the second instruction. Thus we need to patch the second
 399          * instruction of the exception, not the first one
 400          */
 401
 402         patch_branch((struct ppc_inst *)(ibase + (exc / 4) + 1), addr, 0);
 403 }
 404 #endif
 405
 406 #ifdef CONFIG_CODE_PATCHING_SELFTEST
 407
 408 static void __init test_trampoline(void)
 409 {
 410         asm ("nop;\n");
 411 }
 412
 413 #define check(x)        \
 414         if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
 415
 416 static void __init test_branch_iform(void)
 417 {
 418         int err;
 419         struct ppc_inst instr;
 420         unsigned long addr;
 421
 422         addr = (unsigned long)&instr;
 423
 424         /* The simplest case, branch to self, no flags */
 425         check(instr_is_branch_iform(ppc_inst(0x48000000)));
 426         /* All bits of target set, and flags */
 427         check(instr_is_branch_iform(ppc_inst(0x4bffffff)));
 428         /* High bit of opcode set, which is wrong */
 429         check(!instr_is_branch_iform(ppc_inst(0xcbffffff)));
 430         /* Middle bits of opcode set, which is wrong */
 431         check(!instr_is_branch_iform(ppc_inst(0x7bffffff)));
 432
 433         /* Simplest case, branch to self with link */
 434         check(instr_is_branch_iform(ppc_inst(0x48000001)));
 435         /* All bits of targets set */
 436         check(instr_is_branch_iform(ppc_inst(0x4bfffffd)));
 437         /* Some bits of targets set */
 438         check(instr_is_branch_iform(ppc_inst(0x4bff00fd)));
 439         /* Must be a valid branch to start with */
 440         check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
 441
 442         /* Absolute branch to 0x100 */
 443         instr = ppc_inst(0x48000103);
 444         check(instr_is_branch_to_addr(&instr, 0x100));
 445         /* Absolute branch to 0x420fc */
 446         instr = ppc_inst(0x480420ff);
 447         check(instr_is_branch_to_addr(&instr, 0x420fc));
 448         /* Maximum positive relative branch, + 20MB - 4B */
 449         instr = ppc_inst(0x49fffffc);
 450         check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
 451         /* Smallest negative relative branch, - 4B */
 452         instr = ppc_inst(0x4bfffffc);
 453         check(instr_is_branch_to_addr(&instr, addr - 4));
 454         /* Largest negative relative branch, - 32 MB */
 455         instr = ppc_inst(0x4a000000);
 456         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 457
 458         /* Branch to self, with link */
 459         err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
 460         check(instr_is_branch_to_addr(&instr, addr));
 461
 462         /* Branch to self - 0x100, with link */
 463         err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
 464         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 465
 466         /* Branch to self + 0x100, no link */
 467         err = create_branch(&instr, &instr, addr + 0x100, 0);
 468         check(instr_is_branch_to_addr(&instr, addr + 0x100));
 469
 470         /* Maximum relative negative offset, - 32 MB */
 471         err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
 472         check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
 473
 474         /* Out of range relative negative offset, - 32 MB + 4*/
 475         err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
 476         check(err);
 477
 478         /* Out of range relative positive offset, + 32 MB */
 479         err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
 480         check(err);
 481
 482         /* Unaligned target */
 483         err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
 484         check(err);
 485
 486         /* Check flags are masked correctly */
 487         err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
 488         check(instr_is_branch_to_addr(&instr, addr));
 489         check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
 490 }
 491
 492 static void __init test_create_function_call(void)
 493 {
 494         struct ppc_inst *iptr;
 495         unsigned long dest;
 496         struct ppc_inst instr;
 497
 498         /* Check we can create a function call */
 499         iptr = (struct ppc_inst *)ppc_function_entry(test_trampoline);
 500         dest = ppc_function_entry(test_create_function_call);
 501         create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
 502         patch_instruction(iptr, instr);
 503         check(instr_is_branch_to_addr(iptr, dest));
 504 }
 505
 506 static void __init test_branch_bform(void)
 507 {
 508         int err;
 509         unsigned long addr;
 510         struct ppc_inst *iptr, instr;
 511         unsigned int flags;
 512
 513         iptr = &instr;
 514         addr = (unsigned long)iptr;
 515
 516         /* The simplest case, branch to self, no flags */
 517         check(instr_is_branch_bform(ppc_inst(0x40000000)));
 518         /* All bits of target set, and flags */
 519         check(instr_is_branch_bform(ppc_inst(0x43ffffff)));
 520         /* High bit of opcode set, which is wrong */
 521         check(!instr_is_branch_bform(ppc_inst(0xc3ffffff)));
 522         /* Middle bits of opcode set, which is wrong */
 523         check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
 524
 525         /* Absolute conditional branch to 0x100 */
 526         instr = ppc_inst(0x43ff0103);
 527         check(instr_is_branch_to_addr(&instr, 0x100));
 528         /* Absolute conditional branch to 0x20fc */
 529         instr = ppc_inst(0x43ff20ff);
 530         check(instr_is_branch_to_addr(&instr, 0x20fc));
 531         /* Maximum positive relative conditional branch, + 32 KB - 4B */
 532         instr = ppc_inst(0x43ff7ffc);
 533         check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
 534         /* Smallest negative relative conditional branch, - 4B */
 535         instr = ppc_inst(0x43fffffc);
 536         check(instr_is_branch_to_addr(&instr, addr - 4));
 537         /* Largest negative relative conditional branch, - 32 KB */
 538         instr = ppc_inst(0x43ff8000);
 539         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 540
 541         /* All condition code bits set & link */
 542         flags = 0x3ff000 | BRANCH_SET_LINK;
 543
 544         /* Branch to self */
 545         err = create_cond_branch(&instr, iptr, addr, flags);
 546         check(instr_is_branch_to_addr(&instr, addr));
 547
 548         /* Branch to self - 0x100 */
 549         err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
 550         check(instr_is_branch_to_addr(&instr, addr - 0x100));
 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         /* Maximum relative negative offset, - 32 KB */
 557         err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
 558         check(instr_is_branch_to_addr(&instr, addr - 0x8000));
 559
 560         /* Out of range relative negative offset, - 32 KB + 4*/
 561         err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
 562         check(err);
 563
 564         /* Out of range relative positive offset, + 32 KB */
 565         err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
 566         check(err);
 567
 568         /* Unaligned target */
 569         err = create_cond_branch(&instr, iptr, addr + 3, flags);
 570         check(err);
 571
 572         /* Check flags are masked correctly */
 573         err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
 574         check(instr_is_branch_to_addr(&instr, addr));
 575         check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
 576 }
 577
 578 static void __init test_translate_branch(void)
 579 {
 580         unsigned long addr;
 581         void *p, *q;
 582         struct ppc_inst instr;
 583         void *buf;
 584
 585         buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
 586         check(buf);
 587         if (!buf)
 588                 return;
 589
 590         /* Simple case, branch to self moved a little */
 591         p = buf;
 592         addr = (unsigned long)p;
 593         patch_branch(p, addr, 0);
 594         check(instr_is_branch_to_addr(p, addr));
 595         q = p + 4;
 596         translate_branch(&instr, q, p);
 597         patch_instruction(q, instr);
 598         check(instr_is_branch_to_addr(q, addr));
 599
 600         /* Maximum negative case, move b . to addr + 32 MB */
 601         p = buf;
 602         addr = (unsigned long)p;
 603         patch_branch(p, addr, 0);
 604         q = buf + 0x2000000;
 605         translate_branch(&instr, q, p);
 606         patch_instruction(q, instr);
 607         check(instr_is_branch_to_addr(p, addr));
 608         check(instr_is_branch_to_addr(q, addr));
 609         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x4a000000)));
 610
 611         /* Maximum positive case, move x to x - 32 MB + 4 */
 612         p = buf + 0x2000000;
 613         addr = (unsigned long)p;
 614         patch_branch(p, addr, 0);
 615         q = buf + 4;
 616         translate_branch(&instr, q, p);
 617         patch_instruction(q, instr);
 618         check(instr_is_branch_to_addr(p, addr));
 619         check(instr_is_branch_to_addr(q, addr));
 620         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x49fffffc)));
 621
 622         /* Jump to x + 16 MB moved to x + 20 MB */
 623         p = buf;
 624         addr = 0x1000000 + (unsigned long)buf;
 625         patch_branch(p, addr, BRANCH_SET_LINK);
 626         q = buf + 0x1400000;
 627         translate_branch(&instr, q, p);
 628         patch_instruction(q, instr);
 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         translate_branch(&instr, q, p);
 638         patch_instruction(q, instr);
 639         check(instr_is_branch_to_addr(p, addr));
 640         check(instr_is_branch_to_addr(q, addr));
 641
 642
 643         /* Conditional branch tests */
 644
 645         /* Simple case, branch to self moved a little */
 646         p = buf;
 647         addr = (unsigned long)p;
 648         create_cond_branch(&instr, p, addr, 0);
 649         patch_instruction(p, instr);
 650         check(instr_is_branch_to_addr(p, addr));
 651         q = buf + 4;
 652         translate_branch(&instr, q, p);
 653         patch_instruction(q, instr);
 654         check(instr_is_branch_to_addr(q, addr));
 655
 656         /* Maximum negative case, move b . to addr + 32 KB */
 657         p = buf;
 658         addr = (unsigned long)p;
 659         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 660         patch_instruction(p, instr);
 661         q = buf + 0x8000;
 662         translate_branch(&instr, q, p);
 663         patch_instruction(q, instr);
 664         check(instr_is_branch_to_addr(p, addr));
 665         check(instr_is_branch_to_addr(q, addr));
 666         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff8000)));
 667
 668         /* Maximum positive case, move x to x - 32 KB + 4 */
 669         p = buf + 0x8000;
 670         addr = (unsigned long)p;
 671         create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
 672         patch_instruction(p, instr);
 673         q = buf + 4;
 674         translate_branch(&instr, q, p);
 675         patch_instruction(q, instr);
 676         check(instr_is_branch_to_addr(p, addr));
 677         check(instr_is_branch_to_addr(q, addr));
 678         check(ppc_inst_equal(ppc_inst_read(q), ppc_inst(0x43ff7ffc)));
 679
 680         /* Jump to x + 12 KB moved to x + 20 KB */
 681         p = buf;
 682         addr = 0x3000 + (unsigned long)buf;
 683         create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
 684         patch_instruction(p, instr);
 685         q = buf + 0x5000;
 686         translate_branch(&instr, q, p);
 687         patch_instruction(q, instr);
 688         check(instr_is_branch_to_addr(p, addr));
 689         check(instr_is_branch_to_addr(q, addr));
 690
 691         /* Jump to x + 8 KB moved to x - 8 KB + 4 */
 692         p = buf + 0x2000;
 693         addr = 0x4000 + (unsigned long)buf;
 694         create_cond_branch(&instr, p, addr, 0);
 695         patch_instruction(p, instr);
 696         q = buf + 4;
 697         translate_branch(&instr, q, p);
 698         patch_instruction(q, instr);
 699         check(instr_is_branch_to_addr(p, addr));
 700         check(instr_is_branch_to_addr(q, addr));
 701
 702         /* Free the buffer we were using */
 703         vfree(buf);
 704 }
 705
 706 #ifdef CONFIG_PPC64
 707 static void __init test_prefixed_patching(void)
 708 {
 709         extern unsigned int code_patching_test1[];
 710         extern unsigned int code_patching_test1_expected[];
 711         extern unsigned int end_code_patching_test1[];
 712
 713         __patch_instruction((struct ppc_inst *)code_patching_test1,
 714                             ppc_inst_prefix(OP_PREFIX << 26, 0x00000000),
 715                             (struct ppc_inst *)code_patching_test1);
 716
 717         check(!memcmp(code_patching_test1,
 718                       code_patching_test1_expected,
 719                       sizeof(unsigned int) *
 720                       (end_code_patching_test1 - code_patching_test1)));
 721 }
 722 #else
 723 static inline void test_prefixed_patching(void) {}
 724 #endif
 725
 726 static int __init test_code_patching(void)
 727 {
 728         printk(KERN_DEBUG "Running code patching self-tests ...\n");
 729
 730         test_branch_iform();
 731         test_branch_bform();
 732         test_create_function_call();
 733         test_translate_branch();
 734         test_prefixed_patching();
 735
 736         return 0;
 737 }
 738 late_initcall(test_code_patching);
 739
 740 #endif /* CONFIG_CODE_PATCHING_SELFTEST */