arch/arm64/kernel/armv8_deprecated.c

   1 /*
   2  *  Copyright (C) 2014 ARM Limited
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  */
   8
   9 #include <linux/cpu.h>
  10 #include <linux/init.h>
  11 #include <linux/list.h>
  12 #include <linux/perf_event.h>
  13 #include <linux/sched.h>
  14 #include <linux/slab.h>
  15 #include <linux/sysctl.h>
  16 #include <linux/uaccess.h>
  17
  18 #include <asm/cpufeature.h>
  19 #include <asm/insn.h>
  20 #include <asm/sysreg.h>
  21 #include <asm/system_misc.h>
  22 #include <asm/traps.h>
  23 #include <asm/kprobes.h>
  24
  25 #define CREATE_TRACE_POINTS
  26 #include "trace-events-emulation.h"
  27
  28 /*
  29  * The runtime support for deprecated instruction support can be in one of
  30  * following three states -
  31  *
  32  * 0 = undef
  33  * 1 = emulate (software emulation)
  34  * 2 = hw (supported in hardware)
  35  */
  36 enum insn_emulation_mode {
  37         INSN_UNDEF,
  38         INSN_EMULATE,
  39         INSN_HW,
  40 };
  41
  42 enum legacy_insn_status {
  43         INSN_DEPRECATED,
  44         INSN_OBSOLETE,
  45 };
  46
  47 struct insn_emulation_ops {
  48         const char              *name;
  49         enum legacy_insn_status status;
  50         struct undef_hook       *hooks;
  51         int                     (*set_hw_mode)(bool enable);
  52 };
  53
  54 struct insn_emulation {
  55         struct list_head node;
  56         struct insn_emulation_ops *ops;
  57         int current_mode;
  58         int min;
  59         int max;
  60 };
  61
  62 static LIST_HEAD(insn_emulation);
  63 static int nr_insn_emulated __initdata;
  64 static DEFINE_RAW_SPINLOCK(insn_emulation_lock);
  65
  66 static void register_emulation_hooks(struct insn_emulation_ops *ops)
  67 {
  68         struct undef_hook *hook;
  69
  70         BUG_ON(!ops->hooks);
  71
  72         for (hook = ops->hooks; hook->instr_mask; hook++)
  73                 register_undef_hook(hook);
  74
  75         pr_notice("Registered %s emulation handler\n", ops->name);
  76 }
  77
  78 static void remove_emulation_hooks(struct insn_emulation_ops *ops)
  79 {
  80         struct undef_hook *hook;
  81
  82         BUG_ON(!ops->hooks);
  83
  84         for (hook = ops->hooks; hook->instr_mask; hook++)
  85                 unregister_undef_hook(hook);
  86
  87         pr_notice("Removed %s emulation handler\n", ops->name);
  88 }
  89
  90 static void enable_insn_hw_mode(void *data)
  91 {
  92         struct insn_emulation *insn = (struct insn_emulation *)data;
  93         if (insn->ops->set_hw_mode)
  94                 insn->ops->set_hw_mode(true);
  95 }
  96
  97 static void disable_insn_hw_mode(void *data)
  98 {
  99         struct insn_emulation *insn = (struct insn_emulation *)data;
 100         if (insn->ops->set_hw_mode)
 101                 insn->ops->set_hw_mode(false);
 102 }
 103
 104 /* Run set_hw_mode(mode) on all active CPUs */
 105 static int run_all_cpu_set_hw_mode(struct insn_emulation *insn, bool enable)
 106 {
 107         if (!insn->ops->set_hw_mode)
 108                 return -EINVAL;
 109         if (enable)
 110                 on_each_cpu(enable_insn_hw_mode, (void *)insn, true);
 111         else
 112                 on_each_cpu(disable_insn_hw_mode, (void *)insn, true);
 113         return 0;
 114 }
 115
 116 /*
 117  * Run set_hw_mode for all insns on a starting CPU.
 118  * Returns:
 119  *  0           - If all the hooks ran successfully.
 120  * -EINVAL      - At least one hook is not supported by the CPU.
 121  */
 122 static int run_all_insn_set_hw_mode(unsigned int cpu)
 123 {
 124         int rc = 0;
 125         unsigned long flags;
 126         struct insn_emulation *insn;
 127
 128         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 129         list_for_each_entry(insn, &insn_emulation, node) {
 130                 bool enable = (insn->current_mode == INSN_HW);
 131                 if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(enable)) {
 132                         pr_warn("CPU[%u] cannot support the emulation of %s",
 133                                 cpu, insn->ops->name);
 134                         rc = -EINVAL;
 135                 }
 136         }
 137         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 138         return rc;
 139 }
 140
 141 static int update_insn_emulation_mode(struct insn_emulation *insn,
 142                                        enum insn_emulation_mode prev)
 143 {
 144         int ret = 0;
 145
 146         switch (prev) {
 147         case INSN_UNDEF: /* Nothing to be done */
 148                 break;
 149         case INSN_EMULATE:
 150                 remove_emulation_hooks(insn->ops);
 151                 break;
 152         case INSN_HW:
 153                 if (!run_all_cpu_set_hw_mode(insn, false))
 154                         pr_notice("Disabled %s support\n", insn->ops->name);
 155                 break;
 156         }
 157
 158         switch (insn->current_mode) {
 159         case INSN_UNDEF:
 160                 break;
 161         case INSN_EMULATE:
 162                 register_emulation_hooks(insn->ops);
 163                 break;
 164         case INSN_HW:
 165                 ret = run_all_cpu_set_hw_mode(insn, true);
 166                 if (!ret)
 167                         pr_notice("Enabled %s support\n", insn->ops->name);
 168                 break;
 169         }
 170
 171         return ret;
 172 }
 173
 174 static void __init register_insn_emulation(struct insn_emulation_ops *ops)
 175 {
 176         unsigned long flags;
 177         struct insn_emulation *insn;
 178
 179         insn = kzalloc(sizeof(*insn), GFP_KERNEL);
 180         insn->ops = ops;
 181         insn->min = INSN_UNDEF;
 182
 183         switch (ops->status) {
 184         case INSN_DEPRECATED:
 185                 insn->current_mode = INSN_EMULATE;
 186                 /* Disable the HW mode if it was turned on at early boot time */
 187                 run_all_cpu_set_hw_mode(insn, false);
 188                 insn->max = INSN_HW;
 189                 break;
 190         case INSN_OBSOLETE:
 191                 insn->current_mode = INSN_UNDEF;
 192                 insn->max = INSN_EMULATE;
 193                 break;
 194         }
 195
 196         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 197         list_add(&insn->node, &insn_emulation);
 198         nr_insn_emulated++;
 199         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 200
 201         /* Register any handlers if required */
 202         update_insn_emulation_mode(insn, INSN_UNDEF);
 203 }
 204
 205 static int emulation_proc_handler(struct ctl_table *table, int write,
 206                                   void __user *buffer, size_t *lenp,
 207                                   loff_t *ppos)
 208 {
 209         int ret = 0;
 210         struct insn_emulation *insn = (struct insn_emulation *) table->data;
 211         enum insn_emulation_mode prev_mode = insn->current_mode;
 212
 213         table->data = &insn->current_mode;
 214         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 215
 216         if (ret || !write || prev_mode == insn->current_mode)
 217                 goto ret;
 218
 219         ret = update_insn_emulation_mode(insn, prev_mode);
 220         if (ret) {
 221                 /* Mode change failed, revert to previous mode. */
 222                 insn->current_mode = prev_mode;
 223                 update_insn_emulation_mode(insn, INSN_UNDEF);
 224         }
 225 ret:
 226         table->data = insn;
 227         return ret;
 228 }
 229
 230 static void __init register_insn_emulation_sysctl(void)
 231 {
 232         unsigned long flags;
 233         int i = 0;
 234         struct insn_emulation *insn;
 235         struct ctl_table *insns_sysctl, *sysctl;
 236
 237         insns_sysctl = kcalloc(nr_insn_emulated + 1, sizeof(*sysctl),
 238                                GFP_KERNEL);
 239
 240         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 241         list_for_each_entry(insn, &insn_emulation, node) {
 242                 sysctl = &insns_sysctl[i];
 243
 244                 sysctl->mode = 0644;
 245                 sysctl->maxlen = sizeof(int);
 246
 247                 sysctl->procname = insn->ops->name;
 248                 sysctl->data = insn;
 249                 sysctl->extra1 = &insn->min;
 250                 sysctl->extra2 = &insn->max;
 251                 sysctl->proc_handler = emulation_proc_handler;
 252                 i++;
 253         }
 254         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 255
 256         register_sysctl("abi", insns_sysctl);
 257 }
 258
 259 /*
 260  *  Implement emulation of the SWP/SWPB instructions using load-exclusive and
 261  *  store-exclusive.
 262  *
 263  *  Syntax of SWP{B} instruction: SWP{B}<c> <Rt>, <Rt2>, [<Rn>]
 264  *  Where: Rt  = destination
 265  *         Rt2 = source
 266  *         Rn  = address
 267  */
 268
 269 /*
 270  * Error-checking SWP macros implemented using ldxr{b}/stxr{b}
 271  */
 272
 273 /* Arbitrary constant to ensure forward-progress of the LL/SC loop */
 274 #define __SWP_LL_SC_LOOPS       4
 275
 276 #define __user_swpX_asm(data, addr, res, temp, temp2, B)        \
 277 do {                                                            \
 278         uaccess_enable();                                       \
 279         __asm__ __volatile__(                                   \
 280         "       mov             %w3, %w7\n"                     \
 281         "0:     ldxr"B"         %w2, [%4]\n"                    \
 282         "1:     stxr"B"         %w0, %w1, [%4]\n"               \
 283         "       cbz             %w0, 2f\n"                      \
 284         "       sub             %w3, %w3, #1\n"                 \
 285         "       cbnz            %w3, 0b\n"                      \
 286         "       mov             %w0, %w5\n"                     \
 287         "       b               3f\n"                           \
 288         "2:\n"                                                  \
 289         "       mov             %w1, %w2\n"                     \
 290         "3:\n"                                                  \
 291         "       .pushsection     .fixup,\"ax\"\n"               \
 292         "       .align          2\n"                            \
 293         "4:     mov             %w0, %w6\n"                     \
 294         "       b               3b\n"                           \
 295         "       .popsection"                                    \
 296         _ASM_EXTABLE(0b, 4b)                                    \
 297         _ASM_EXTABLE(1b, 4b)                                    \
 298         : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \
 299         : "r" ((unsigned long)addr), "i" (-EAGAIN),             \
 300           "i" (-EFAULT),                                        \
 301           "i" (__SWP_LL_SC_LOOPS)                               \
 302         : "memory");                                            \
 303         uaccess_disable();                                      \
 304 } while (0)
 305
 306 #define __user_swp_asm(data, addr, res, temp, temp2) \
 307         __user_swpX_asm(data, addr, res, temp, temp2, "")
 308 #define __user_swpb_asm(data, addr, res, temp, temp2) \
 309         __user_swpX_asm(data, addr, res, temp, temp2, "b")
 310
 311 /*
 312  * Bit 22 of the instruction encoding distinguishes between
 313  * the SWP and SWPB variants (bit set means SWPB).
 314  */
 315 #define TYPE_SWPB (1 << 22)
 316
 317 static int emulate_swpX(unsigned int address, unsigned int *data,
 318                         unsigned int type)
 319 {
 320         unsigned int res = 0;
 321
 322         if ((type != TYPE_SWPB) && (address & 0x3)) {
 323                 /* SWP to unaligned address not permitted */
 324                 pr_debug("SWP instruction on unaligned pointer!\n");
 325                 return -EFAULT;
 326         }
 327
 328         while (1) {
 329                 unsigned long temp, temp2;
 330
 331                 if (type == TYPE_SWPB)
 332                         __user_swpb_asm(*data, address, res, temp, temp2);
 333                 else
 334                         __user_swp_asm(*data, address, res, temp, temp2);
 335
 336                 if (likely(res != -EAGAIN) || signal_pending(current))
 337                         break;
 338
 339                 cond_resched();
 340         }
 341
 342         return res;
 343 }
 344
 345 #define ARM_OPCODE_CONDTEST_FAIL   0
 346 #define ARM_OPCODE_CONDTEST_PASS   1
 347 #define ARM_OPCODE_CONDTEST_UNCOND 2
 348
 349 #define ARM_OPCODE_CONDITION_UNCOND     0xf
 350
 351 static unsigned int __kprobes aarch32_check_condition(u32 opcode, u32 psr)
 352 {
 353         u32 cc_bits  = opcode >> 28;
 354
 355         if (cc_bits != ARM_OPCODE_CONDITION_UNCOND) {
 356                 if ((*aarch32_opcode_cond_checks[cc_bits])(psr))
 357                         return ARM_OPCODE_CONDTEST_PASS;
 358                 else
 359                         return ARM_OPCODE_CONDTEST_FAIL;
 360         }
 361         return ARM_OPCODE_CONDTEST_UNCOND;
 362 }
 363
 364 /*
 365  * swp_handler logs the id of calling process, dissects the instruction, sanity
 366  * checks the memory location, calls emulate_swpX for the actual operation and
 367  * deals with fixup/error handling before returning
 368  */
 369 static int swp_handler(struct pt_regs *regs, u32 instr)
 370 {
 371         u32 destreg, data, type, address = 0;
 372         const void __user *user_ptr;
 373         int rn, rt2, res = 0;
 374
 375         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 376
 377         type = instr & TYPE_SWPB;
 378
 379         switch (aarch32_check_condition(instr, regs->pstate)) {
 380         case ARM_OPCODE_CONDTEST_PASS:
 381                 break;
 382         case ARM_OPCODE_CONDTEST_FAIL:
 383                 /* Condition failed - return to next instruction */
 384                 goto ret;
 385         case ARM_OPCODE_CONDTEST_UNCOND:
 386                 /* If unconditional encoding - not a SWP, undef */
 387                 return -EFAULT;
 388         default:
 389                 return -EINVAL;
 390         }
 391
 392         rn = aarch32_insn_extract_reg_num(instr, A32_RN_OFFSET);
 393         rt2 = aarch32_insn_extract_reg_num(instr, A32_RT2_OFFSET);
 394
 395         address = (u32)regs->user_regs.regs[rn];
 396         data    = (u32)regs->user_regs.regs[rt2];
 397         destreg = aarch32_insn_extract_reg_num(instr, A32_RT_OFFSET);
 398
 399         pr_debug("addr in r%d->0x%08x, dest is r%d, source in r%d->0x%08x)\n",
 400                 rn, address, destreg,
 401                 aarch32_insn_extract_reg_num(instr, A32_RT2_OFFSET), data);
 402
 403         /* Check access in reasonable access range for both SWP and SWPB */
 404         user_ptr = (const void __user *)(unsigned long)(address & ~3);
 405         if (!access_ok(VERIFY_WRITE, user_ptr, 4)) {
 406                 pr_debug("SWP{B} emulation: access to 0x%08x not allowed!\n",
 407                         address);
 408                 goto fault;
 409         }
 410
 411         res = emulate_swpX(address, &data, type);
 412         if (res == -EFAULT)
 413                 goto fault;
 414         else if (res == 0)
 415                 regs->user_regs.regs[destreg] = data;
 416
 417 ret:
 418         if (type == TYPE_SWPB)
 419                 trace_instruction_emulation("swpb", regs->pc);
 420         else
 421                 trace_instruction_emulation("swp", regs->pc);
 422
 423         pr_warn_ratelimited("\"%s\" (%ld) uses obsolete SWP{B} instruction at 0x%llx\n",
 424                         current->comm, (unsigned long)current->pid, regs->pc);
 425
 426         arm64_skip_faulting_instruction(regs, 4);
 427         return 0;
 428
 429 fault:
 430         pr_debug("SWP{B} emulation: access caused memory abort!\n");
 431         arm64_notify_segfault(address);
 432
 433         return 0;
 434 }
 435
 436 /*
 437  * Only emulate SWP/SWPB executed in ARM state/User mode.
 438  * The kernel must be SWP free and SWP{B} does not exist in Thumb.
 439  */
 440 static struct undef_hook swp_hooks[] = {
 441         {
 442                 .instr_mask     = 0x0fb00ff0,
 443                 .instr_val      = 0x01000090,
 444                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 445                 .pstate_val     = COMPAT_PSR_MODE_USR,
 446                 .fn             = swp_handler
 447         },
 448         { }
 449 };
 450
 451 static struct insn_emulation_ops swp_ops = {
 452         .name = "swp",
 453         .status = INSN_OBSOLETE,
 454         .hooks = swp_hooks,
 455         .set_hw_mode = NULL,
 456 };
 457
 458 static int cp15barrier_handler(struct pt_regs *regs, u32 instr)
 459 {
 460         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 461
 462         switch (aarch32_check_condition(instr, regs->pstate)) {
 463         case ARM_OPCODE_CONDTEST_PASS:
 464                 break;
 465         case ARM_OPCODE_CONDTEST_FAIL:
 466                 /* Condition failed - return to next instruction */
 467                 goto ret;
 468         case ARM_OPCODE_CONDTEST_UNCOND:
 469                 /* If unconditional encoding - not a barrier instruction */
 470                 return -EFAULT;
 471         default:
 472                 return -EINVAL;
 473         }
 474
 475         switch (aarch32_insn_mcr_extract_crm(instr)) {
 476         case 10:
 477                 /*
 478                  * dmb - mcr p15, 0, Rt, c7, c10, 5
 479                  * dsb - mcr p15, 0, Rt, c7, c10, 4
 480                  */
 481                 if (aarch32_insn_mcr_extract_opc2(instr) == 5) {
 482                         dmb(sy);
 483                         trace_instruction_emulation(
 484                                 "mcr p15, 0, Rt, c7, c10, 5 ; dmb", regs->pc);
 485                 } else {
 486                         dsb(sy);
 487                         trace_instruction_emulation(
 488                                 "mcr p15, 0, Rt, c7, c10, 4 ; dsb", regs->pc);
 489                 }
 490                 break;
 491         case 5:
 492                 /*
 493                  * isb - mcr p15, 0, Rt, c7, c5, 4
 494                  *
 495                  * Taking an exception or returning from one acts as an
 496                  * instruction barrier. So no explicit barrier needed here.
 497                  */
 498                 trace_instruction_emulation(
 499                         "mcr p15, 0, Rt, c7, c5, 4 ; isb", regs->pc);
 500                 break;
 501         }
 502
 503 ret:
 504         pr_warn_ratelimited("\"%s\" (%ld) uses deprecated CP15 Barrier instruction at 0x%llx\n",
 505                         current->comm, (unsigned long)current->pid, regs->pc);
 506
 507         arm64_skip_faulting_instruction(regs, 4);
 508         return 0;
 509 }
 510
 511 static int cp15_barrier_set_hw_mode(bool enable)
 512 {
 513         if (enable)
 514                 config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
 515         else
 516                 config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
 517         return 0;
 518 }
 519
 520 static struct undef_hook cp15_barrier_hooks[] = {
 521         {
 522                 .instr_mask     = 0x0fff0fdf,
 523                 .instr_val      = 0x0e070f9a,
 524                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 525                 .pstate_val     = COMPAT_PSR_MODE_USR,
 526                 .fn             = cp15barrier_handler,
 527         },
 528         {
 529                 .instr_mask     = 0x0fff0fff,
 530                 .instr_val      = 0x0e070f95,
 531                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 532                 .pstate_val     = COMPAT_PSR_MODE_USR,
 533                 .fn             = cp15barrier_handler,
 534         },
 535         { }
 536 };
 537
 538 static struct insn_emulation_ops cp15_barrier_ops = {
 539         .name = "cp15_barrier",
 540         .status = INSN_DEPRECATED,
 541         .hooks = cp15_barrier_hooks,
 542         .set_hw_mode = cp15_barrier_set_hw_mode,
 543 };
 544
 545 static int setend_set_hw_mode(bool enable)
 546 {
 547         if (!cpu_supports_mixed_endian_el0())
 548                 return -EINVAL;
 549
 550         if (enable)
 551                 config_sctlr_el1(SCTLR_EL1_SED, 0);
 552         else
 553                 config_sctlr_el1(0, SCTLR_EL1_SED);
 554         return 0;
 555 }
 556
 557 static int compat_setend_handler(struct pt_regs *regs, u32 big_endian)
 558 {
 559         char *insn;
 560
 561         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 562
 563         if (big_endian) {
 564                 insn = "setend be";
 565                 regs->pstate |= COMPAT_PSR_E_BIT;
 566         } else {
 567                 insn = "setend le";
 568                 regs->pstate &= ~COMPAT_PSR_E_BIT;
 569         }
 570
 571         trace_instruction_emulation(insn, regs->pc);
 572         pr_warn_ratelimited("\"%s\" (%ld) uses deprecated setend instruction at 0x%llx\n",
 573                         current->comm, (unsigned long)current->pid, regs->pc);
 574
 575         return 0;
 576 }
 577
 578 static int a32_setend_handler(struct pt_regs *regs, u32 instr)
 579 {
 580         int rc = compat_setend_handler(regs, (instr >> 9) & 1);
 581         arm64_skip_faulting_instruction(regs, 4);
 582         return rc;
 583 }
 584
 585 static int t16_setend_handler(struct pt_regs *regs, u32 instr)
 586 {
 587         int rc = compat_setend_handler(regs, (instr >> 3) & 1);
 588         arm64_skip_faulting_instruction(regs, 2);
 589         return rc;
 590 }
 591
 592 static struct undef_hook setend_hooks[] = {
 593         {
 594                 .instr_mask     = 0xfffffdff,
 595                 .instr_val      = 0xf1010000,
 596                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 597                 .pstate_val     = COMPAT_PSR_MODE_USR,
 598                 .fn             = a32_setend_handler,
 599         },
 600         {
 601                 /* Thumb mode */
 602                 .instr_mask     = 0x0000fff7,
 603                 .instr_val      = 0x0000b650,
 604                 .pstate_mask    = (COMPAT_PSR_T_BIT | COMPAT_PSR_MODE_MASK),
 605                 .pstate_val     = (COMPAT_PSR_T_BIT | COMPAT_PSR_MODE_USR),
 606                 .fn             = t16_setend_handler,
 607         },
 608         {}
 609 };
 610
 611 static struct insn_emulation_ops setend_ops = {
 612         .name = "setend",
 613         .status = INSN_DEPRECATED,
 614         .hooks = setend_hooks,
 615         .set_hw_mode = setend_set_hw_mode,
 616 };
 617
 618 /*
 619  * Invoked as late_initcall, since not needed before init spawned.
 620  */
 621 static int __init armv8_deprecated_init(void)
 622 {
 623         if (IS_ENABLED(CONFIG_SWP_EMULATION))
 624                 register_insn_emulation(&swp_ops);
 625
 626         if (IS_ENABLED(CONFIG_CP15_BARRIER_EMULATION))
 627                 register_insn_emulation(&cp15_barrier_ops);
 628
 629         if (IS_ENABLED(CONFIG_SETEND_EMULATION)) {
 630                 if(system_supports_mixed_endian_el0())
 631                         register_insn_emulation(&setend_ops);
 632                 else
 633                         pr_info("setend instruction emulation is not supported on this system\n");
 634         }
 635
 636         cpuhp_setup_state_nocalls(CPUHP_AP_ARM64_ISNDEP_STARTING,
 637                                   "arm64/isndep:starting",
 638                                   run_all_insn_set_hw_mode, NULL);
 639         register_insn_emulation_sysctl();
 640
 641         return 0;
 642 }
 643
 644 core_initcall(armv8_deprecated_init);