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
  17 #include <asm/alternative.h>
  18 #include <asm/cpufeature.h>
  19 #include <asm/insn.h>
  20 #include <asm/opcodes.h>
  21 #include <asm/sysreg.h>
  22 #include <asm/system_misc.h>
  23 #include <asm/traps.h>
  24 #include <asm/uaccess.h>
  25 #include <asm/cpufeature.h>
  26
  27 #define CREATE_TRACE_POINTS
  28 #include "trace-events-emulation.h"
  29
  30 /*
  31  * The runtime support for deprecated instruction support can be in one of
  32  * following three states -
  33  *
  34  * 0 = undef
  35  * 1 = emulate (software emulation)
  36  * 2 = hw (supported in hardware)
  37  */
  38 enum insn_emulation_mode {
  39         INSN_UNDEF,
  40         INSN_EMULATE,
  41         INSN_HW,
  42 };
  43
  44 enum legacy_insn_status {
  45         INSN_DEPRECATED,
  46         INSN_OBSOLETE,
  47 };
  48
  49 struct insn_emulation_ops {
  50         const char              *name;
  51         enum legacy_insn_status status;
  52         struct undef_hook       *hooks;
  53         int                     (*set_hw_mode)(bool enable);
  54 };
  55
  56 struct insn_emulation {
  57         struct list_head node;
  58         struct insn_emulation_ops *ops;
  59         int current_mode;
  60         int min;
  61         int max;
  62 };
  63
  64 static LIST_HEAD(insn_emulation);
  65 static int nr_insn_emulated __initdata;
  66 static DEFINE_RAW_SPINLOCK(insn_emulation_lock);
  67
  68 static void register_emulation_hooks(struct insn_emulation_ops *ops)
  69 {
  70         struct undef_hook *hook;
  71
  72         BUG_ON(!ops->hooks);
  73
  74         for (hook = ops->hooks; hook->instr_mask; hook++)
  75                 register_undef_hook(hook);
  76
  77         pr_notice("Registered %s emulation handler\n", ops->name);
  78 }
  79
  80 static void remove_emulation_hooks(struct insn_emulation_ops *ops)
  81 {
  82         struct undef_hook *hook;
  83
  84         BUG_ON(!ops->hooks);
  85
  86         for (hook = ops->hooks; hook->instr_mask; hook++)
  87                 unregister_undef_hook(hook);
  88
  89         pr_notice("Removed %s emulation handler\n", ops->name);
  90 }
  91
  92 static void enable_insn_hw_mode(void *data)
  93 {
  94         struct insn_emulation *insn = (struct insn_emulation *)data;
  95         if (insn->ops->set_hw_mode)
  96                 insn->ops->set_hw_mode(true);
  97 }
  98
  99 static void disable_insn_hw_mode(void *data)
 100 {
 101         struct insn_emulation *insn = (struct insn_emulation *)data;
 102         if (insn->ops->set_hw_mode)
 103                 insn->ops->set_hw_mode(false);
 104 }
 105
 106 /* Run set_hw_mode(mode) on all active CPUs */
 107 static int run_all_cpu_set_hw_mode(struct insn_emulation *insn, bool enable)
 108 {
 109         if (!insn->ops->set_hw_mode)
 110                 return -EINVAL;
 111         if (enable)
 112                 on_each_cpu(enable_insn_hw_mode, (void *)insn, true);
 113         else
 114                 on_each_cpu(disable_insn_hw_mode, (void *)insn, true);
 115         return 0;
 116 }
 117
 118 /*
 119  * Run set_hw_mode for all insns on a starting CPU.
 120  * Returns:
 121  *  0           - If all the hooks ran successfully.
 122  * -EINVAL      - At least one hook is not supported by the CPU.
 123  */
 124 static int run_all_insn_set_hw_mode(unsigned long cpu)
 125 {
 126         int rc = 0;
 127         unsigned long flags;
 128         struct insn_emulation *insn;
 129
 130         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 131         list_for_each_entry(insn, &insn_emulation, node) {
 132                 bool enable = (insn->current_mode == INSN_HW);
 133                 if (insn->ops->set_hw_mode && insn->ops->set_hw_mode(enable)) {
 134                         pr_warn("CPU[%ld] cannot support the emulation of %s",
 135                                 cpu, insn->ops->name);
 136                         rc = -EINVAL;
 137                 }
 138         }
 139         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 140         return rc;
 141 }
 142
 143 static int update_insn_emulation_mode(struct insn_emulation *insn,
 144                                        enum insn_emulation_mode prev)
 145 {
 146         int ret = 0;
 147
 148         switch (prev) {
 149         case INSN_UNDEF: /* Nothing to be done */
 150                 break;
 151         case INSN_EMULATE:
 152                 remove_emulation_hooks(insn->ops);
 153                 break;
 154         case INSN_HW:
 155                 if (!run_all_cpu_set_hw_mode(insn, false))
 156                         pr_notice("Disabled %s support\n", insn->ops->name);
 157                 break;
 158         }
 159
 160         switch (insn->current_mode) {
 161         case INSN_UNDEF:
 162                 break;
 163         case INSN_EMULATE:
 164                 register_emulation_hooks(insn->ops);
 165                 break;
 166         case INSN_HW:
 167                 ret = run_all_cpu_set_hw_mode(insn, true);
 168                 if (!ret)
 169                         pr_notice("Enabled %s support\n", insn->ops->name);
 170                 break;
 171         }
 172
 173         return ret;
 174 }
 175
 176 static void __init register_insn_emulation(struct insn_emulation_ops *ops)
 177 {
 178         unsigned long flags;
 179         struct insn_emulation *insn;
 180
 181         insn = kzalloc(sizeof(*insn), GFP_KERNEL);
 182         insn->ops = ops;
 183         insn->min = INSN_UNDEF;
 184
 185         switch (ops->status) {
 186         case INSN_DEPRECATED:
 187                 insn->current_mode = INSN_EMULATE;
 188                 /* Disable the HW mode if it was turned on at early boot time */
 189                 run_all_cpu_set_hw_mode(insn, false);
 190                 insn->max = INSN_HW;
 191                 break;
 192         case INSN_OBSOLETE:
 193                 insn->current_mode = INSN_UNDEF;
 194                 insn->max = INSN_EMULATE;
 195                 break;
 196         }
 197
 198         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 199         list_add(&insn->node, &insn_emulation);
 200         nr_insn_emulated++;
 201         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 202
 203         /* Register any handlers if required */
 204         update_insn_emulation_mode(insn, INSN_UNDEF);
 205 }
 206
 207 static int emulation_proc_handler(struct ctl_table *table, int write,
 208                                   void __user *buffer, size_t *lenp,
 209                                   loff_t *ppos)
 210 {
 211         int ret = 0;
 212         struct insn_emulation *insn = (struct insn_emulation *) table->data;
 213         enum insn_emulation_mode prev_mode = insn->current_mode;
 214
 215         table->data = &insn->current_mode;
 216         ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
 217
 218         if (ret || !write || prev_mode == insn->current_mode)
 219                 goto ret;
 220
 221         ret = update_insn_emulation_mode(insn, prev_mode);
 222         if (ret) {
 223                 /* Mode change failed, revert to previous mode. */
 224                 insn->current_mode = prev_mode;
 225                 update_insn_emulation_mode(insn, INSN_UNDEF);
 226         }
 227 ret:
 228         table->data = insn;
 229         return ret;
 230 }
 231
 232 static struct ctl_table ctl_abi[] = {
 233         {
 234                 .procname = "abi",
 235                 .mode = 0555,
 236         },
 237         { }
 238 };
 239
 240 static void __init register_insn_emulation_sysctl(struct ctl_table *table)
 241 {
 242         unsigned long flags;
 243         int i = 0;
 244         struct insn_emulation *insn;
 245         struct ctl_table *insns_sysctl, *sysctl;
 246
 247         insns_sysctl = kzalloc(sizeof(*sysctl) * (nr_insn_emulated + 1),
 248                               GFP_KERNEL);
 249
 250         raw_spin_lock_irqsave(&insn_emulation_lock, flags);
 251         list_for_each_entry(insn, &insn_emulation, node) {
 252                 sysctl = &insns_sysctl[i];
 253
 254                 sysctl->mode = 0644;
 255                 sysctl->maxlen = sizeof(int);
 256
 257                 sysctl->procname = insn->ops->name;
 258                 sysctl->data = insn;
 259                 sysctl->extra1 = &insn->min;
 260                 sysctl->extra2 = &insn->max;
 261                 sysctl->proc_handler = emulation_proc_handler;
 262                 i++;
 263         }
 264         raw_spin_unlock_irqrestore(&insn_emulation_lock, flags);
 265
 266         table->child = insns_sysctl;
 267         register_sysctl_table(table);
 268 }
 269
 270 /*
 271  *  Implement emulation of the SWP/SWPB instructions using load-exclusive and
 272  *  store-exclusive.
 273  *
 274  *  Syntax of SWP{B} instruction: SWP{B}<c> <Rt>, <Rt2>, [<Rn>]
 275  *  Where: Rt  = destination
 276  *         Rt2 = source
 277  *         Rn  = address
 278  */
 279
 280 /*
 281  * Error-checking SWP macros implemented using ldxr{b}/stxr{b}
 282  */
 283 #define __user_swpX_asm(data, addr, res, temp, B)               \
 284         __asm__ __volatile__(                                   \
 285         ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,    \
 286                     CONFIG_ARM64_PAN)                           \
 287         "0:     ldxr"B"         %w2, [%3]\n"                    \
 288         "1:     stxr"B"         %w0, %w1, [%3]\n"               \
 289         "       cbz             %w0, 2f\n"                      \
 290         "       mov             %w0, %w4\n"                     \
 291         "       b               3f\n"                           \
 292         "2:\n"                                                  \
 293         "       mov             %w1, %w2\n"                     \
 294         "3:\n"                                                  \
 295         "       .pushsection     .fixup,\"ax\"\n"               \
 296         "       .align          2\n"                            \
 297         "4:     mov             %w0, %w5\n"                     \
 298         "       b               3b\n"                           \
 299         "       .popsection"                                    \
 300         _ASM_EXTABLE(0b, 4b)                                    \
 301         _ASM_EXTABLE(1b, 4b)                                    \
 302         ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,    \
 303                 CONFIG_ARM64_PAN)                               \
 304         : "=&r" (res), "+r" (data), "=&r" (temp)                \
 305         : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT)              \
 306         : "memory")
 307
 308 #define __user_swp_asm(data, addr, res, temp) \
 309         __user_swpX_asm(data, addr, res, temp, "")
 310 #define __user_swpb_asm(data, addr, res, temp) \
 311         __user_swpX_asm(data, addr, res, temp, "b")
 312
 313 /*
 314  * Bit 22 of the instruction encoding distinguishes between
 315  * the SWP and SWPB variants (bit set means SWPB).
 316  */
 317 #define TYPE_SWPB (1 << 22)
 318
 319 static int emulate_swpX(unsigned int address, unsigned int *data,
 320                         unsigned int type)
 321 {
 322         unsigned int res = 0;
 323
 324         if ((type != TYPE_SWPB) && (address & 0x3)) {
 325                 /* SWP to unaligned address not permitted */
 326                 pr_debug("SWP instruction on unaligned pointer!\n");
 327                 return -EFAULT;
 328         }
 329
 330         while (1) {
 331                 unsigned long temp;
 332
 333                 if (type == TYPE_SWPB)
 334                         __user_swpb_asm(*data, address, res, temp);
 335                 else
 336                         __user_swp_asm(*data, address, res, temp);
 337
 338                 if (likely(res != -EAGAIN) || signal_pending(current))
 339                         break;
 340
 341                 cond_resched();
 342         }
 343
 344         return res;
 345 }
 346
 347 /*
 348  * swp_handler logs the id of calling process, dissects the instruction, sanity
 349  * checks the memory location, calls emulate_swpX for the actual operation and
 350  * deals with fixup/error handling before returning
 351  */
 352 static int swp_handler(struct pt_regs *regs, u32 instr)
 353 {
 354         u32 destreg, data, type, address = 0;
 355         int rn, rt2, res = 0;
 356
 357         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 358
 359         type = instr & TYPE_SWPB;
 360
 361         switch (arm_check_condition(instr, regs->pstate)) {
 362         case ARM_OPCODE_CONDTEST_PASS:
 363                 break;
 364         case ARM_OPCODE_CONDTEST_FAIL:
 365                 /* Condition failed - return to next instruction */
 366                 goto ret;
 367         case ARM_OPCODE_CONDTEST_UNCOND:
 368                 /* If unconditional encoding - not a SWP, undef */
 369                 return -EFAULT;
 370         default:
 371                 return -EINVAL;
 372         }
 373
 374         rn = aarch32_insn_extract_reg_num(instr, A32_RN_OFFSET);
 375         rt2 = aarch32_insn_extract_reg_num(instr, A32_RT2_OFFSET);
 376
 377         address = (u32)regs->user_regs.regs[rn];
 378         data    = (u32)regs->user_regs.regs[rt2];
 379         destreg = aarch32_insn_extract_reg_num(instr, A32_RT_OFFSET);
 380
 381         pr_debug("addr in r%d->0x%08x, dest is r%d, source in r%d->0x%08x)\n",
 382                 rn, address, destreg,
 383                 aarch32_insn_extract_reg_num(instr, A32_RT2_OFFSET), data);
 384
 385         /* Check access in reasonable access range for both SWP and SWPB */
 386         if (!access_ok(VERIFY_WRITE, (address & ~3), 4)) {
 387                 pr_debug("SWP{B} emulation: access to 0x%08x not allowed!\n",
 388                         address);
 389                 goto fault;
 390         }
 391
 392         res = emulate_swpX(address, &data, type);
 393         if (res == -EFAULT)
 394                 goto fault;
 395         else if (res == 0)
 396                 regs->user_regs.regs[destreg] = data;
 397
 398 ret:
 399         if (type == TYPE_SWPB)
 400                 trace_instruction_emulation("swpb", regs->pc);
 401         else
 402                 trace_instruction_emulation("swp", regs->pc);
 403
 404         pr_warn_ratelimited("\"%s\" (%ld) uses obsolete SWP{B} instruction at 0x%llx\n",
 405                         current->comm, (unsigned long)current->pid, regs->pc);
 406
 407         regs->pc += 4;
 408         return 0;
 409
 410 fault:
 411         pr_debug("SWP{B} emulation: access caused memory abort!\n");
 412         arm64_notify_segfault(regs, address);
 413
 414         return 0;
 415 }
 416
 417 /*
 418  * Only emulate SWP/SWPB executed in ARM state/User mode.
 419  * The kernel must be SWP free and SWP{B} does not exist in Thumb.
 420  */
 421 static struct undef_hook swp_hooks[] = {
 422         {
 423                 .instr_mask     = 0x0fb00ff0,
 424                 .instr_val      = 0x01000090,
 425                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 426                 .pstate_val     = COMPAT_PSR_MODE_USR,
 427                 .fn             = swp_handler
 428         },
 429         { }
 430 };
 431
 432 static struct insn_emulation_ops swp_ops = {
 433         .name = "swp",
 434         .status = INSN_OBSOLETE,
 435         .hooks = swp_hooks,
 436         .set_hw_mode = NULL,
 437 };
 438
 439 static int cp15barrier_handler(struct pt_regs *regs, u32 instr)
 440 {
 441         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 442
 443         switch (arm_check_condition(instr, regs->pstate)) {
 444         case ARM_OPCODE_CONDTEST_PASS:
 445                 break;
 446         case ARM_OPCODE_CONDTEST_FAIL:
 447                 /* Condition failed - return to next instruction */
 448                 goto ret;
 449         case ARM_OPCODE_CONDTEST_UNCOND:
 450                 /* If unconditional encoding - not a barrier instruction */
 451                 return -EFAULT;
 452         default:
 453                 return -EINVAL;
 454         }
 455
 456         switch (aarch32_insn_mcr_extract_crm(instr)) {
 457         case 10:
 458                 /*
 459                  * dmb - mcr p15, 0, Rt, c7, c10, 5
 460                  * dsb - mcr p15, 0, Rt, c7, c10, 4
 461                  */
 462                 if (aarch32_insn_mcr_extract_opc2(instr) == 5) {
 463                         dmb(sy);
 464                         trace_instruction_emulation(
 465                                 "mcr p15, 0, Rt, c7, c10, 5 ; dmb", regs->pc);
 466                 } else {
 467                         dsb(sy);
 468                         trace_instruction_emulation(
 469                                 "mcr p15, 0, Rt, c7, c10, 4 ; dsb", regs->pc);
 470                 }
 471                 break;
 472         case 5:
 473                 /*
 474                  * isb - mcr p15, 0, Rt, c7, c5, 4
 475                  *
 476                  * Taking an exception or returning from one acts as an
 477                  * instruction barrier. So no explicit barrier needed here.
 478                  */
 479                 trace_instruction_emulation(
 480                         "mcr p15, 0, Rt, c7, c5, 4 ; isb", regs->pc);
 481                 break;
 482         }
 483
 484 ret:
 485         pr_warn_ratelimited("\"%s\" (%ld) uses deprecated CP15 Barrier instruction at 0x%llx\n",
 486                         current->comm, (unsigned long)current->pid, regs->pc);
 487
 488         regs->pc += 4;
 489         return 0;
 490 }
 491
 492 static int cp15_barrier_set_hw_mode(bool enable)
 493 {
 494         if (enable)
 495                 config_sctlr_el1(0, SCTLR_EL1_CP15BEN);
 496         else
 497                 config_sctlr_el1(SCTLR_EL1_CP15BEN, 0);
 498         return 0;
 499 }
 500
 501 static struct undef_hook cp15_barrier_hooks[] = {
 502         {
 503                 .instr_mask     = 0x0fff0fdf,
 504                 .instr_val      = 0x0e070f9a,
 505                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 506                 .pstate_val     = COMPAT_PSR_MODE_USR,
 507                 .fn             = cp15barrier_handler,
 508         },
 509         {
 510                 .instr_mask     = 0x0fff0fff,
 511                 .instr_val      = 0x0e070f95,
 512                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 513                 .pstate_val     = COMPAT_PSR_MODE_USR,
 514                 .fn             = cp15barrier_handler,
 515         },
 516         { }
 517 };
 518
 519 static struct insn_emulation_ops cp15_barrier_ops = {
 520         .name = "cp15_barrier",
 521         .status = INSN_DEPRECATED,
 522         .hooks = cp15_barrier_hooks,
 523         .set_hw_mode = cp15_barrier_set_hw_mode,
 524 };
 525
 526 static int setend_set_hw_mode(bool enable)
 527 {
 528         if (!cpu_supports_mixed_endian_el0())
 529                 return -EINVAL;
 530
 531         if (enable)
 532                 config_sctlr_el1(SCTLR_EL1_SED, 0);
 533         else
 534                 config_sctlr_el1(0, SCTLR_EL1_SED);
 535         return 0;
 536 }
 537
 538 static int compat_setend_handler(struct pt_regs *regs, u32 big_endian)
 539 {
 540         char *insn;
 541
 542         perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS, 1, regs, regs->pc);
 543
 544         if (big_endian) {
 545                 insn = "setend be";
 546                 regs->pstate |= COMPAT_PSR_E_BIT;
 547         } else {
 548                 insn = "setend le";
 549                 regs->pstate &= ~COMPAT_PSR_E_BIT;
 550         }
 551
 552         trace_instruction_emulation(insn, regs->pc);
 553         pr_warn_ratelimited("\"%s\" (%ld) uses deprecated setend instruction at 0x%llx\n",
 554                         current->comm, (unsigned long)current->pid, regs->pc);
 555
 556         return 0;
 557 }
 558
 559 static int a32_setend_handler(struct pt_regs *regs, u32 instr)
 560 {
 561         int rc = compat_setend_handler(regs, (instr >> 9) & 1);
 562         regs->pc += 4;
 563         return rc;
 564 }
 565
 566 static int t16_setend_handler(struct pt_regs *regs, u32 instr)
 567 {
 568         int rc = compat_setend_handler(regs, (instr >> 3) & 1);
 569         regs->pc += 2;
 570         return rc;
 571 }
 572
 573 static struct undef_hook setend_hooks[] = {
 574         {
 575                 .instr_mask     = 0xfffffdff,
 576                 .instr_val      = 0xf1010000,
 577                 .pstate_mask    = COMPAT_PSR_MODE_MASK,
 578                 .pstate_val     = COMPAT_PSR_MODE_USR,
 579                 .fn             = a32_setend_handler,
 580         },
 581         {
 582                 /* Thumb mode */
 583                 .instr_mask     = 0x0000fff7,
 584                 .instr_val      = 0x0000b650,
 585                 .pstate_mask    = (COMPAT_PSR_T_BIT | COMPAT_PSR_MODE_MASK),
 586                 .pstate_val     = (COMPAT_PSR_T_BIT | COMPAT_PSR_MODE_USR),
 587                 .fn             = t16_setend_handler,
 588         },
 589         {}
 590 };
 591
 592 static struct insn_emulation_ops setend_ops = {
 593         .name = "setend",
 594         .status = INSN_DEPRECATED,
 595         .hooks = setend_hooks,
 596         .set_hw_mode = setend_set_hw_mode,
 597 };
 598
 599 static int insn_cpu_hotplug_notify(struct notifier_block *b,
 600                               unsigned long action, void *hcpu)
 601 {
 602         int rc = 0;
 603         if ((action & ~CPU_TASKS_FROZEN) == CPU_STARTING)
 604                 rc = run_all_insn_set_hw_mode((unsigned long)hcpu);
 605
 606         return notifier_from_errno(rc);
 607 }
 608
 609 static struct notifier_block insn_cpu_hotplug_notifier = {
 610         .notifier_call = insn_cpu_hotplug_notify,
 611 };
 612
 613 /*
 614  * Invoked as late_initcall, since not needed before init spawned.
 615  */
 616 static int __init armv8_deprecated_init(void)
 617 {
 618         if (IS_ENABLED(CONFIG_SWP_EMULATION))
 619                 register_insn_emulation(&swp_ops);
 620
 621         if (IS_ENABLED(CONFIG_CP15_BARRIER_EMULATION))
 622                 register_insn_emulation(&cp15_barrier_ops);
 623
 624         if (IS_ENABLED(CONFIG_SETEND_EMULATION)) {
 625                 if(system_supports_mixed_endian_el0())
 626                         register_insn_emulation(&setend_ops);
 627                 else
 628                         pr_info("setend instruction emulation is not supported on the system");
 629         }
 630
 631         register_cpu_notifier(&insn_cpu_hotplug_notifier);
 632         register_insn_emulation_sysctl(ctl_abi);
 633
 634         return 0;
 635 }
 636
 637 late_initcall(armv8_deprecated_init);