1 /* 2 * Copyright 2008 Michael Ellerman, IBM Corporation. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 */ 9 10 #include <linux/kernel.h> 11 #include <linux/kprobes.h> 12 #include <linux/vmalloc.h> 13 #include <linux/init.h> 14 #include <linux/mm.h> 15 #include <linux/cpuhotplug.h> 16 #include <linux/slab.h> 17 #include <linux/uaccess.h> 18 #include <linux/kprobes.h> 19 20 #include <asm/pgtable.h> 21 #include <asm/tlbflush.h> 22 #include <asm/page.h> 23 #include <asm/code-patching.h> 24 #include <asm/setup.h> 25 26 static int __patch_instruction(unsigned int *exec_addr, unsigned int instr, 27 unsigned int *patch_addr) 28 { 29 int err; 30 31 __put_user_size(instr, patch_addr, 4, err); 32 if (err) 33 return err; 34 35 asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr), 36 "r" (exec_addr)); 37 38 return 0; 39 } 40 41 int raw_patch_instruction(unsigned int *addr, unsigned int instr) 42 { 43 return __patch_instruction(addr, instr, addr); 44 } 45 46 #ifdef CONFIG_STRICT_KERNEL_RWX 47 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area); 48 49 static int text_area_cpu_up(unsigned int cpu) 50 { 51 struct vm_struct *area; 52 53 area = get_vm_area(PAGE_SIZE, VM_ALLOC); 54 if (!area) { 55 WARN_ONCE(1, "Failed to create text area for cpu %d\n", 56 cpu); 57 return -1; 58 } 59 this_cpu_write(text_poke_area, area); 60 61 return 0; 62 } 63 64 static int text_area_cpu_down(unsigned int cpu) 65 { 66 free_vm_area(this_cpu_read(text_poke_area)); 67 return 0; 68 } 69 70 /* 71 * Run as a late init call. This allows all the boot time patching to be done 72 * simply by patching the code, and then we're called here prior to 73 * mark_rodata_ro(), which happens after all init calls are run. Although 74 * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge 75 * it as being preferable to a kernel that will crash later when someone tries 76 * to use patch_instruction(). 77 */ 78 static int __init setup_text_poke_area(void) 79 { 80 BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, 81 "powerpc/text_poke:online", text_area_cpu_up, 82 text_area_cpu_down)); 83 84 return 0; 85 } 86 late_initcall(setup_text_poke_area); 87 88 /* 89 * This can be called for kernel text or a module. 90 */ 91 static int map_patch_area(void *addr, unsigned long text_poke_addr) 92 { 93 unsigned long pfn; 94 int err; 95 96 if (is_vmalloc_addr(addr)) 97 pfn = vmalloc_to_pfn(addr); 98 else 99 pfn = __pa_symbol(addr) >> PAGE_SHIFT; 100 101 err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), 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 pgd_t *pgdp; 116 117 pgdp = pgd_offset_k(addr); 118 if (unlikely(!pgdp)) 119 return -EINVAL; 120 121 pudp = pud_offset(pgdp, 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 } 143 144 static int do_patch_instruction(unsigned int *addr, unsigned int instr) 145 { 146 int err; 147 unsigned int *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 = (unsigned int *)(text_poke_addr) + 169 ((kaddr & ~PAGE_MASK) / sizeof(unsigned int)); 170 171 __patch_instruction(addr, instr, patch_addr); 172 173 err = unmap_patch_area(text_poke_addr); 174 if (err) 175 pr_warn("failed to unmap %lx\n", text_poke_addr); 176 177 out: 178 local_irq_restore(flags); 179 180 return err; 181 } 182 #else /* !CONFIG_STRICT_KERNEL_RWX */ 183 184 static int do_patch_instruction(unsigned int *addr, unsigned int instr) 185 { 186 return raw_patch_instruction(addr, instr); 187 } 188 189 #endif /* CONFIG_STRICT_KERNEL_RWX */ 190 191 int patch_instruction(unsigned int *addr, unsigned int instr) 192 { 193 /* Make sure we aren't patching a freed init section */ 194 if (init_mem_is_free && init_section_contains(addr, 4)) { 195 pr_debug("Skipping init section patching addr: 0x%px\n", addr); 196 return 0; 197 } 198 return do_patch_instruction(addr, instr); 199 } 200 NOKPROBE_SYMBOL(patch_instruction); 201 202 int patch_branch(unsigned int *addr, unsigned long target, int flags) 203 { 204 return patch_instruction(addr, create_branch(addr, target, flags)); 205 } 206 207 bool is_offset_in_branch_range(long offset) 208 { 209 /* 210 * Powerpc branch instruction is : 211 * 212 * 0 6 30 31 213 * +---------+----------------+---+---+ 214 * | opcode | LI |AA |LK | 215 * +---------+----------------+---+---+ 216 * Where AA = 0 and LK = 0 217 * 218 * LI is a signed 24 bits integer. The real branch offset is computed 219 * by: imm32 = SignExtend(LI:'0b00', 32); 220 * 221 * So the maximum forward branch should be: 222 * (0x007fffff << 2) = 0x01fffffc = 0x1fffffc 223 * The maximum backward branch should be: 224 * (0xff800000 << 2) = 0xfe000000 = -0x2000000 225 */ 226 return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3)); 227 } 228 229 /* 230 * Helper to check if a given instruction is a conditional branch 231 * Derived from the conditional checks in analyse_instr() 232 */ 233 bool is_conditional_branch(unsigned int instr) 234 { 235 unsigned int opcode = instr >> 26; 236 237 if (opcode == 16) /* bc, bca, bcl, bcla */ 238 return true; 239 if (opcode == 19) { 240 switch ((instr >> 1) & 0x3ff) { 241 case 16: /* bclr, bclrl */ 242 case 528: /* bcctr, bcctrl */ 243 case 560: /* bctar, bctarl */ 244 return true; 245 } 246 } 247 return false; 248 } 249 NOKPROBE_SYMBOL(is_conditional_branch); 250 251 unsigned int create_branch(const unsigned int *addr, 252 unsigned long target, int flags) 253 { 254 unsigned int instruction; 255 long offset; 256 257 offset = target; 258 if (! (flags & BRANCH_ABSOLUTE)) 259 offset = offset - (unsigned long)addr; 260 261 /* Check we can represent the target in the instruction format */ 262 if (!is_offset_in_branch_range(offset)) 263 return 0; 264 265 /* Mask out the flags and target, so they don't step on each other. */ 266 instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC); 267 268 return instruction; 269 } 270 271 unsigned int create_cond_branch(const unsigned int *addr, 272 unsigned long target, int flags) 273 { 274 unsigned int instruction; 275 long offset; 276 277 offset = target; 278 if (! (flags & BRANCH_ABSOLUTE)) 279 offset = offset - (unsigned long)addr; 280 281 /* Check we can represent the target in the instruction format */ 282 if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3) 283 return 0; 284 285 /* Mask out the flags and target, so they don't step on each other. */ 286 instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC); 287 288 return instruction; 289 } 290 291 static unsigned int branch_opcode(unsigned int instr) 292 { 293 return (instr >> 26) & 0x3F; 294 } 295 296 static int instr_is_branch_iform(unsigned int instr) 297 { 298 return branch_opcode(instr) == 18; 299 } 300 301 static int instr_is_branch_bform(unsigned int instr) 302 { 303 return branch_opcode(instr) == 16; 304 } 305 306 int instr_is_relative_branch(unsigned int instr) 307 { 308 if (instr & BRANCH_ABSOLUTE) 309 return 0; 310 311 return instr_is_branch_iform(instr) || instr_is_branch_bform(instr); 312 } 313 314 int instr_is_relative_link_branch(unsigned int instr) 315 { 316 return instr_is_relative_branch(instr) && (instr & BRANCH_SET_LINK); 317 } 318 319 static unsigned long branch_iform_target(const unsigned int *instr) 320 { 321 signed long imm; 322 323 imm = *instr & 0x3FFFFFC; 324 325 /* If the top bit of the immediate value is set this is negative */ 326 if (imm & 0x2000000) 327 imm -= 0x4000000; 328 329 if ((*instr & BRANCH_ABSOLUTE) == 0) 330 imm += (unsigned long)instr; 331 332 return (unsigned long)imm; 333 } 334 335 static unsigned long branch_bform_target(const unsigned int *instr) 336 { 337 signed long imm; 338 339 imm = *instr & 0xFFFC; 340 341 /* If the top bit of the immediate value is set this is negative */ 342 if (imm & 0x8000) 343 imm -= 0x10000; 344 345 if ((*instr & BRANCH_ABSOLUTE) == 0) 346 imm += (unsigned long)instr; 347 348 return (unsigned long)imm; 349 } 350 351 unsigned long branch_target(const unsigned int *instr) 352 { 353 if (instr_is_branch_iform(*instr)) 354 return branch_iform_target(instr); 355 else if (instr_is_branch_bform(*instr)) 356 return branch_bform_target(instr); 357 358 return 0; 359 } 360 361 int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr) 362 { 363 if (instr_is_branch_iform(*instr) || instr_is_branch_bform(*instr)) 364 return branch_target(instr) == addr; 365 366 return 0; 367 } 368 369 unsigned int translate_branch(const unsigned int *dest, const unsigned int *src) 370 { 371 unsigned long target; 372 373 target = branch_target(src); 374 375 if (instr_is_branch_iform(*src)) 376 return create_branch(dest, target, *src); 377 else if (instr_is_branch_bform(*src)) 378 return create_cond_branch(dest, target, *src); 379 380 return 0; 381 } 382 383 #ifdef CONFIG_PPC_BOOK3E_64 384 void __patch_exception(int exc, unsigned long addr) 385 { 386 extern unsigned int interrupt_base_book3e; 387 unsigned int *ibase = &interrupt_base_book3e; 388 389 /* Our exceptions vectors start with a NOP and -then- a branch 390 * to deal with single stepping from userspace which stops on 391 * the second instruction. Thus we need to patch the second 392 * instruction of the exception, not the first one 393 */ 394 395 patch_branch(ibase + (exc / 4) + 1, addr, 0); 396 } 397 #endif 398 399 #ifdef CONFIG_CODE_PATCHING_SELFTEST 400 401 static void __init test_trampoline(void) 402 { 403 asm ("nop;\n"); 404 } 405 406 #define check(x) \ 407 if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__); 408 409 static void __init test_branch_iform(void) 410 { 411 unsigned int instr; 412 unsigned long addr; 413 414 addr = (unsigned long)&instr; 415 416 /* The simplest case, branch to self, no flags */ 417 check(instr_is_branch_iform(0x48000000)); 418 /* All bits of target set, and flags */ 419 check(instr_is_branch_iform(0x4bffffff)); 420 /* High bit of opcode set, which is wrong */ 421 check(!instr_is_branch_iform(0xcbffffff)); 422 /* Middle bits of opcode set, which is wrong */ 423 check(!instr_is_branch_iform(0x7bffffff)); 424 425 /* Simplest case, branch to self with link */ 426 check(instr_is_branch_iform(0x48000001)); 427 /* All bits of targets set */ 428 check(instr_is_branch_iform(0x4bfffffd)); 429 /* Some bits of targets set */ 430 check(instr_is_branch_iform(0x4bff00fd)); 431 /* Must be a valid branch to start with */ 432 check(!instr_is_branch_iform(0x7bfffffd)); 433 434 /* Absolute branch to 0x100 */ 435 instr = 0x48000103; 436 check(instr_is_branch_to_addr(&instr, 0x100)); 437 /* Absolute branch to 0x420fc */ 438 instr = 0x480420ff; 439 check(instr_is_branch_to_addr(&instr, 0x420fc)); 440 /* Maximum positive relative branch, + 20MB - 4B */ 441 instr = 0x49fffffc; 442 check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC)); 443 /* Smallest negative relative branch, - 4B */ 444 instr = 0x4bfffffc; 445 check(instr_is_branch_to_addr(&instr, addr - 4)); 446 /* Largest negative relative branch, - 32 MB */ 447 instr = 0x4a000000; 448 check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); 449 450 /* Branch to self, with link */ 451 instr = create_branch(&instr, addr, BRANCH_SET_LINK); 452 check(instr_is_branch_to_addr(&instr, addr)); 453 454 /* Branch to self - 0x100, with link */ 455 instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK); 456 check(instr_is_branch_to_addr(&instr, addr - 0x100)); 457 458 /* Branch to self + 0x100, no link */ 459 instr = create_branch(&instr, addr + 0x100, 0); 460 check(instr_is_branch_to_addr(&instr, addr + 0x100)); 461 462 /* Maximum relative negative offset, - 32 MB */ 463 instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK); 464 check(instr_is_branch_to_addr(&instr, addr - 0x2000000)); 465 466 /* Out of range relative negative offset, - 32 MB + 4*/ 467 instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK); 468 check(instr == 0); 469 470 /* Out of range relative positive offset, + 32 MB */ 471 instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK); 472 check(instr == 0); 473 474 /* Unaligned target */ 475 instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK); 476 check(instr == 0); 477 478 /* Check flags are masked correctly */ 479 instr = create_branch(&instr, addr, 0xFFFFFFFC); 480 check(instr_is_branch_to_addr(&instr, addr)); 481 check(instr == 0x48000000); 482 } 483 484 static void __init test_create_function_call(void) 485 { 486 unsigned int *iptr; 487 unsigned long dest; 488 489 /* Check we can create a function call */ 490 iptr = (unsigned int *)ppc_function_entry(test_trampoline); 491 dest = ppc_function_entry(test_create_function_call); 492 patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK)); 493 check(instr_is_branch_to_addr(iptr, dest)); 494 } 495 496 static void __init test_branch_bform(void) 497 { 498 unsigned long addr; 499 unsigned int *iptr, instr, flags; 500 501 iptr = &instr; 502 addr = (unsigned long)iptr; 503 504 /* The simplest case, branch to self, no flags */ 505 check(instr_is_branch_bform(0x40000000)); 506 /* All bits of target set, and flags */ 507 check(instr_is_branch_bform(0x43ffffff)); 508 /* High bit of opcode set, which is wrong */ 509 check(!instr_is_branch_bform(0xc3ffffff)); 510 /* Middle bits of opcode set, which is wrong */ 511 check(!instr_is_branch_bform(0x7bffffff)); 512 513 /* Absolute conditional branch to 0x100 */ 514 instr = 0x43ff0103; 515 check(instr_is_branch_to_addr(&instr, 0x100)); 516 /* Absolute conditional branch to 0x20fc */ 517 instr = 0x43ff20ff; 518 check(instr_is_branch_to_addr(&instr, 0x20fc)); 519 /* Maximum positive relative conditional branch, + 32 KB - 4B */ 520 instr = 0x43ff7ffc; 521 check(instr_is_branch_to_addr(&instr, addr + 0x7FFC)); 522 /* Smallest negative relative conditional branch, - 4B */ 523 instr = 0x43fffffc; 524 check(instr_is_branch_to_addr(&instr, addr - 4)); 525 /* Largest negative relative conditional branch, - 32 KB */ 526 instr = 0x43ff8000; 527 check(instr_is_branch_to_addr(&instr, addr - 0x8000)); 528 529 /* All condition code bits set & link */ 530 flags = 0x3ff000 | BRANCH_SET_LINK; 531 532 /* Branch to self */ 533 instr = create_cond_branch(iptr, addr, flags); 534 check(instr_is_branch_to_addr(&instr, addr)); 535 536 /* Branch to self - 0x100 */ 537 instr = create_cond_branch(iptr, addr - 0x100, flags); 538 check(instr_is_branch_to_addr(&instr, addr - 0x100)); 539 540 /* Branch to self + 0x100 */ 541 instr = create_cond_branch(iptr, addr + 0x100, flags); 542 check(instr_is_branch_to_addr(&instr, addr + 0x100)); 543 544 /* Maximum relative negative offset, - 32 KB */ 545 instr = create_cond_branch(iptr, addr - 0x8000, flags); 546 check(instr_is_branch_to_addr(&instr, addr - 0x8000)); 547 548 /* Out of range relative negative offset, - 32 KB + 4*/ 549 instr = create_cond_branch(iptr, addr - 0x8004, flags); 550 check(instr == 0); 551 552 /* Out of range relative positive offset, + 32 KB */ 553 instr = create_cond_branch(iptr, addr + 0x8000, flags); 554 check(instr == 0); 555 556 /* Unaligned target */ 557 instr = create_cond_branch(iptr, addr + 3, flags); 558 check(instr == 0); 559 560 /* Check flags are masked correctly */ 561 instr = create_cond_branch(iptr, addr, 0xFFFFFFFC); 562 check(instr_is_branch_to_addr(&instr, addr)); 563 check(instr == 0x43FF0000); 564 } 565 566 static void __init test_translate_branch(void) 567 { 568 unsigned long addr; 569 unsigned int *p, *q; 570 void *buf; 571 572 buf = vmalloc(PAGE_ALIGN(0x2000000 + 1)); 573 check(buf); 574 if (!buf) 575 return; 576 577 /* Simple case, branch to self moved a little */ 578 p = buf; 579 addr = (unsigned long)p; 580 patch_branch(p, addr, 0); 581 check(instr_is_branch_to_addr(p, addr)); 582 q = p + 1; 583 patch_instruction(q, translate_branch(q, p)); 584 check(instr_is_branch_to_addr(q, addr)); 585 586 /* Maximum negative case, move b . to addr + 32 MB */ 587 p = buf; 588 addr = (unsigned long)p; 589 patch_branch(p, addr, 0); 590 q = buf + 0x2000000; 591 patch_instruction(q, translate_branch(q, p)); 592 check(instr_is_branch_to_addr(p, addr)); 593 check(instr_is_branch_to_addr(q, addr)); 594 check(*q == 0x4a000000); 595 596 /* Maximum positive case, move x to x - 32 MB + 4 */ 597 p = buf + 0x2000000; 598 addr = (unsigned long)p; 599 patch_branch(p, addr, 0); 600 q = buf + 4; 601 patch_instruction(q, translate_branch(q, p)); 602 check(instr_is_branch_to_addr(p, addr)); 603 check(instr_is_branch_to_addr(q, addr)); 604 check(*q == 0x49fffffc); 605 606 /* Jump to x + 16 MB moved to x + 20 MB */ 607 p = buf; 608 addr = 0x1000000 + (unsigned long)buf; 609 patch_branch(p, addr, BRANCH_SET_LINK); 610 q = buf + 0x1400000; 611 patch_instruction(q, translate_branch(q, p)); 612 check(instr_is_branch_to_addr(p, addr)); 613 check(instr_is_branch_to_addr(q, addr)); 614 615 /* Jump to x + 16 MB moved to x - 16 MB + 4 */ 616 p = buf + 0x1000000; 617 addr = 0x2000000 + (unsigned long)buf; 618 patch_branch(p, addr, 0); 619 q = buf + 4; 620 patch_instruction(q, translate_branch(q, p)); 621 check(instr_is_branch_to_addr(p, addr)); 622 check(instr_is_branch_to_addr(q, addr)); 623 624 625 /* Conditional branch tests */ 626 627 /* Simple case, branch to self moved a little */ 628 p = buf; 629 addr = (unsigned long)p; 630 patch_instruction(p, create_cond_branch(p, addr, 0)); 631 check(instr_is_branch_to_addr(p, addr)); 632 q = p + 1; 633 patch_instruction(q, translate_branch(q, p)); 634 check(instr_is_branch_to_addr(q, addr)); 635 636 /* Maximum negative case, move b . to addr + 32 KB */ 637 p = buf; 638 addr = (unsigned long)p; 639 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); 640 q = buf + 0x8000; 641 patch_instruction(q, translate_branch(q, p)); 642 check(instr_is_branch_to_addr(p, addr)); 643 check(instr_is_branch_to_addr(q, addr)); 644 check(*q == 0x43ff8000); 645 646 /* Maximum positive case, move x to x - 32 KB + 4 */ 647 p = buf + 0x8000; 648 addr = (unsigned long)p; 649 patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC)); 650 q = buf + 4; 651 patch_instruction(q, translate_branch(q, p)); 652 check(instr_is_branch_to_addr(p, addr)); 653 check(instr_is_branch_to_addr(q, addr)); 654 check(*q == 0x43ff7ffc); 655 656 /* Jump to x + 12 KB moved to x + 20 KB */ 657 p = buf; 658 addr = 0x3000 + (unsigned long)buf; 659 patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK)); 660 q = buf + 0x5000; 661 patch_instruction(q, translate_branch(q, p)); 662 check(instr_is_branch_to_addr(p, addr)); 663 check(instr_is_branch_to_addr(q, addr)); 664 665 /* Jump to x + 8 KB moved to x - 8 KB + 4 */ 666 p = buf + 0x2000; 667 addr = 0x4000 + (unsigned long)buf; 668 patch_instruction(p, create_cond_branch(p, addr, 0)); 669 q = buf + 4; 670 patch_instruction(q, translate_branch(q, p)); 671 check(instr_is_branch_to_addr(p, addr)); 672 check(instr_is_branch_to_addr(q, addr)); 673 674 /* Free the buffer we were using */ 675 vfree(buf); 676 } 677 678 static int __init test_code_patching(void) 679 { 680 printk(KERN_DEBUG "Running code patching self-tests ...\n"); 681 682 test_branch_iform(); 683 test_branch_bform(); 684 test_create_function_call(); 685 test_translate_branch(); 686 687 return 0; 688 } 689 late_initcall(test_code_patching); 690 691 #endif /* CONFIG_CODE_PATCHING_SELFTEST */ 692