arch/arm64/kernel/traps.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Based on arch/arm/kernel/traps.c
   4  *
   5  * Copyright (C) 1995-2009 Russell King
   6  * Copyright (C) 2012 ARM Ltd.
   7  */
   8
   9 #include <linux/bug.h>
  10 #include <linux/context_tracking.h>
  11 #include <linux/signal.h>
  12 #include <linux/kallsyms.h>
  13 #include <linux/kprobes.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/hardirq.h>
  17 #include <linux/kdebug.h>
  18 #include <linux/module.h>
  19 #include <linux/kexec.h>
  20 #include <linux/delay.h>
  21 #include <linux/init.h>
  22 #include <linux/sched/signal.h>
  23 #include <linux/sched/debug.h>
  24 #include <linux/sched/task_stack.h>
  25 #include <linux/sizes.h>
  26 #include <linux/syscalls.h>
  27 #include <linux/mm_types.h>
  28 #include <linux/kasan.h>
  29
  30 #include <asm/atomic.h>
  31 #include <asm/bug.h>
  32 #include <asm/cpufeature.h>
  33 #include <asm/daifflags.h>
  34 #include <asm/debug-monitors.h>
  35 #include <asm/esr.h>
  36 #include <asm/exception.h>
  37 #include <asm/extable.h>
  38 #include <asm/insn.h>
  39 #include <asm/kprobes.h>
  40 #include <asm/patching.h>
  41 #include <asm/traps.h>
  42 #include <asm/smp.h>
  43 #include <asm/stack_pointer.h>
  44 #include <asm/stacktrace.h>
  45 #include <asm/system_misc.h>
  46 #include <asm/sysreg.h>
  47
  48 static bool __kprobes __check_eq(unsigned long pstate)
  49 {
  50         return (pstate & PSR_Z_BIT) != 0;
  51 }
  52
  53 static bool __kprobes __check_ne(unsigned long pstate)
  54 {
  55         return (pstate & PSR_Z_BIT) == 0;
  56 }
  57
  58 static bool __kprobes __check_cs(unsigned long pstate)
  59 {
  60         return (pstate & PSR_C_BIT) != 0;
  61 }
  62
  63 static bool __kprobes __check_cc(unsigned long pstate)
  64 {
  65         return (pstate & PSR_C_BIT) == 0;
  66 }
  67
  68 static bool __kprobes __check_mi(unsigned long pstate)
  69 {
  70         return (pstate & PSR_N_BIT) != 0;
  71 }
  72
  73 static bool __kprobes __check_pl(unsigned long pstate)
  74 {
  75         return (pstate & PSR_N_BIT) == 0;
  76 }
  77
  78 static bool __kprobes __check_vs(unsigned long pstate)
  79 {
  80         return (pstate & PSR_V_BIT) != 0;
  81 }
  82
  83 static bool __kprobes __check_vc(unsigned long pstate)
  84 {
  85         return (pstate & PSR_V_BIT) == 0;
  86 }
  87
  88 static bool __kprobes __check_hi(unsigned long pstate)
  89 {
  90         pstate &= ~(pstate >> 1);       /* PSR_C_BIT &= ~PSR_Z_BIT */
  91         return (pstate & PSR_C_BIT) != 0;
  92 }
  93
  94 static bool __kprobes __check_ls(unsigned long pstate)
  95 {
  96         pstate &= ~(pstate >> 1);       /* PSR_C_BIT &= ~PSR_Z_BIT */
  97         return (pstate & PSR_C_BIT) == 0;
  98 }
  99
 100 static bool __kprobes __check_ge(unsigned long pstate)
 101 {
 102         pstate ^= (pstate << 3);        /* PSR_N_BIT ^= PSR_V_BIT */
 103         return (pstate & PSR_N_BIT) == 0;
 104 }
 105
 106 static bool __kprobes __check_lt(unsigned long pstate)
 107 {
 108         pstate ^= (pstate << 3);        /* PSR_N_BIT ^= PSR_V_BIT */
 109         return (pstate & PSR_N_BIT) != 0;
 110 }
 111
 112 static bool __kprobes __check_gt(unsigned long pstate)
 113 {
 114         /*PSR_N_BIT ^= PSR_V_BIT */
 115         unsigned long temp = pstate ^ (pstate << 3);
 116
 117         temp |= (pstate << 1);  /*PSR_N_BIT |= PSR_Z_BIT */
 118         return (temp & PSR_N_BIT) == 0;
 119 }
 120
 121 static bool __kprobes __check_le(unsigned long pstate)
 122 {
 123         /*PSR_N_BIT ^= PSR_V_BIT */
 124         unsigned long temp = pstate ^ (pstate << 3);
 125
 126         temp |= (pstate << 1);  /*PSR_N_BIT |= PSR_Z_BIT */
 127         return (temp & PSR_N_BIT) != 0;
 128 }
 129
 130 static bool __kprobes __check_al(unsigned long pstate)
 131 {
 132         return true;
 133 }
 134
 135 /*
 136  * Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that
 137  * it behaves identically to 0b1110 ("al").
 138  */
 139 pstate_check_t * const aarch32_opcode_cond_checks[16] = {
 140         __check_eq, __check_ne, __check_cs, __check_cc,
 141         __check_mi, __check_pl, __check_vs, __check_vc,
 142         __check_hi, __check_ls, __check_ge, __check_lt,
 143         __check_gt, __check_le, __check_al, __check_al
 144 };
 145
 146 int show_unhandled_signals = 0;
 147
 148 static void dump_kernel_instr(const char *lvl, struct pt_regs *regs)
 149 {
 150         unsigned long addr = instruction_pointer(regs);
 151         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 152         int i;
 153
 154         if (user_mode(regs))
 155                 return;
 156
 157         for (i = -4; i < 1; i++) {
 158                 unsigned int val, bad;
 159
 160                 bad = aarch64_insn_read(&((u32 *)addr)[i], &val);
 161
 162                 if (!bad)
 163                         p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
 164                 else {
 165                         p += sprintf(p, "bad PC value");
 166                         break;
 167                 }
 168         }
 169
 170         printk("%sCode: %s\n", lvl, str);
 171 }
 172
 173 #ifdef CONFIG_PREEMPT
 174 #define S_PREEMPT " PREEMPT"
 175 #elif defined(CONFIG_PREEMPT_RT)
 176 #define S_PREEMPT " PREEMPT_RT"
 177 #else
 178 #define S_PREEMPT ""
 179 #endif
 180
 181 #define S_SMP " SMP"
 182
 183 static int __die(const char *str, int err, struct pt_regs *regs)
 184 {
 185         static int die_counter;
 186         int ret;
 187
 188         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 189                  str, err, ++die_counter);
 190
 191         /* trap and error numbers are mostly meaningless on ARM */
 192         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 193         if (ret == NOTIFY_STOP)
 194                 return ret;
 195
 196         print_modules();
 197         show_regs(regs);
 198
 199         dump_kernel_instr(KERN_EMERG, regs);
 200
 201         return ret;
 202 }
 203
 204 static DEFINE_RAW_SPINLOCK(die_lock);
 205
 206 /*
 207  * This function is protected against re-entrancy.
 208  */
 209 void die(const char *str, struct pt_regs *regs, int err)
 210 {
 211         int ret;
 212         unsigned long flags;
 213
 214         raw_spin_lock_irqsave(&die_lock, flags);
 215
 216         oops_enter();
 217
 218         console_verbose();
 219         bust_spinlocks(1);
 220         ret = __die(str, err, regs);
 221
 222         if (regs && kexec_should_crash(current))
 223                 crash_kexec(regs);
 224
 225         bust_spinlocks(0);
 226         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 227         oops_exit();
 228
 229         if (in_interrupt())
 230                 panic("%s: Fatal exception in interrupt", str);
 231         if (panic_on_oops)
 232                 panic("%s: Fatal exception", str);
 233
 234         raw_spin_unlock_irqrestore(&die_lock, flags);
 235
 236         if (ret != NOTIFY_STOP)
 237                 make_task_dead(SIGSEGV);
 238 }
 239
 240 static void arm64_show_signal(int signo, const char *str)
 241 {
 242         static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
 243                                       DEFAULT_RATELIMIT_BURST);
 244         struct task_struct *tsk = current;
 245         unsigned long esr = tsk->thread.fault_code;
 246         struct pt_regs *regs = task_pt_regs(tsk);
 247
 248         /* Leave if the signal won't be shown */
 249         if (!show_unhandled_signals ||
 250             !unhandled_signal(tsk, signo) ||
 251             !__ratelimit(&rs))
 252                 return;
 253
 254         pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk));
 255         if (esr)
 256                 pr_cont("%s, ESR 0x%016lx, ", esr_get_class_string(esr), esr);
 257
 258         pr_cont("%s", str);
 259         print_vma_addr(KERN_CONT " in ", regs->pc);
 260         pr_cont("\n");
 261         __show_regs(regs);
 262 }
 263
 264 void arm64_force_sig_fault(int signo, int code, unsigned long far,
 265                            const char *str)
 266 {
 267         arm64_show_signal(signo, str);
 268         if (signo == SIGKILL)
 269                 force_sig(SIGKILL);
 270         else
 271                 force_sig_fault(signo, code, (void __user *)far);
 272 }
 273
 274 void arm64_force_sig_mceerr(int code, unsigned long far, short lsb,
 275                             const char *str)
 276 {
 277         arm64_show_signal(SIGBUS, str);
 278         force_sig_mceerr(code, (void __user *)far, lsb);
 279 }
 280
 281 void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far,
 282                                        const char *str)
 283 {
 284         arm64_show_signal(SIGTRAP, str);
 285         force_sig_ptrace_errno_trap(errno, (void __user *)far);
 286 }
 287
 288 void arm64_notify_die(const char *str, struct pt_regs *regs,
 289                       int signo, int sicode, unsigned long far,
 290                       unsigned long err)
 291 {
 292         if (user_mode(regs)) {
 293                 WARN_ON(regs != current_pt_regs());
 294                 current->thread.fault_address = 0;
 295                 current->thread.fault_code = err;
 296
 297                 arm64_force_sig_fault(signo, sicode, far, str);
 298         } else {
 299                 die(str, regs, err);
 300         }
 301 }
 302
 303 #ifdef CONFIG_COMPAT
 304 #define PSTATE_IT_1_0_SHIFT     25
 305 #define PSTATE_IT_1_0_MASK      (0x3 << PSTATE_IT_1_0_SHIFT)
 306 #define PSTATE_IT_7_2_SHIFT     10
 307 #define PSTATE_IT_7_2_MASK      (0x3f << PSTATE_IT_7_2_SHIFT)
 308
 309 static u32 compat_get_it_state(struct pt_regs *regs)
 310 {
 311         u32 it, pstate = regs->pstate;
 312
 313         it  = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT;
 314         it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2;
 315
 316         return it;
 317 }
 318
 319 static void compat_set_it_state(struct pt_regs *regs, u32 it)
 320 {
 321         u32 pstate_it;
 322
 323         pstate_it  = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK;
 324         pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK;
 325
 326         regs->pstate &= ~PSR_AA32_IT_MASK;
 327         regs->pstate |= pstate_it;
 328 }
 329
 330 static void advance_itstate(struct pt_regs *regs)
 331 {
 332         u32 it;
 333
 334         /* ARM mode */
 335         if (!(regs->pstate & PSR_AA32_T_BIT) ||
 336             !(regs->pstate & PSR_AA32_IT_MASK))
 337                 return;
 338
 339         it  = compat_get_it_state(regs);
 340
 341         /*
 342          * If this is the last instruction of the block, wipe the IT
 343          * state. Otherwise advance it.
 344          */
 345         if (!(it & 7))
 346                 it = 0;
 347         else
 348                 it = (it & 0xe0) | ((it << 1) & 0x1f);
 349
 350         compat_set_it_state(regs, it);
 351 }
 352 #else
 353 static void advance_itstate(struct pt_regs *regs)
 354 {
 355 }
 356 #endif
 357
 358 void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size)
 359 {
 360         regs->pc += size;
 361
 362         /*
 363          * If we were single stepping, we want to get the step exception after
 364          * we return from the trap.
 365          */
 366         if (user_mode(regs))
 367                 user_fastforward_single_step(current);
 368
 369         if (compat_user_mode(regs))
 370                 advance_itstate(regs);
 371         else
 372                 regs->pstate &= ~PSR_BTYPE_MASK;
 373 }
 374
 375 static LIST_HEAD(undef_hook);
 376 static DEFINE_RAW_SPINLOCK(undef_lock);
 377
 378 void register_undef_hook(struct undef_hook *hook)
 379 {
 380         unsigned long flags;
 381
 382         raw_spin_lock_irqsave(&undef_lock, flags);
 383         list_add(&hook->node, &undef_hook);
 384         raw_spin_unlock_irqrestore(&undef_lock, flags);
 385 }
 386
 387 void unregister_undef_hook(struct undef_hook *hook)
 388 {
 389         unsigned long flags;
 390
 391         raw_spin_lock_irqsave(&undef_lock, flags);
 392         list_del(&hook->node);
 393         raw_spin_unlock_irqrestore(&undef_lock, flags);
 394 }
 395
 396 static int call_undef_hook(struct pt_regs *regs)
 397 {
 398         struct undef_hook *hook;
 399         unsigned long flags;
 400         u32 instr;
 401         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 402         unsigned long pc = instruction_pointer(regs);
 403
 404         if (!user_mode(regs)) {
 405                 __le32 instr_le;
 406                 if (get_kernel_nofault(instr_le, (__le32 *)pc))
 407                         goto exit;
 408                 instr = le32_to_cpu(instr_le);
 409         } else if (compat_thumb_mode(regs)) {
 410                 /* 16-bit Thumb instruction */
 411                 __le16 instr_le;
 412                 if (get_user(instr_le, (__le16 __user *)pc))
 413                         goto exit;
 414                 instr = le16_to_cpu(instr_le);
 415                 if (aarch32_insn_is_wide(instr)) {
 416                         u32 instr2;
 417
 418                         if (get_user(instr_le, (__le16 __user *)(pc + 2)))
 419                                 goto exit;
 420                         instr2 = le16_to_cpu(instr_le);
 421                         instr = (instr << 16) | instr2;
 422                 }
 423         } else {
 424                 /* 32-bit ARM instruction */
 425                 __le32 instr_le;
 426                 if (get_user(instr_le, (__le32 __user *)pc))
 427                         goto exit;
 428                 instr = le32_to_cpu(instr_le);
 429         }
 430
 431         raw_spin_lock_irqsave(&undef_lock, flags);
 432         list_for_each_entry(hook, &undef_hook, node)
 433                 if ((instr & hook->instr_mask) == hook->instr_val &&
 434                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 435                         fn = hook->fn;
 436
 437         raw_spin_unlock_irqrestore(&undef_lock, flags);
 438 exit:
 439         return fn ? fn(regs, instr) : 1;
 440 }
 441
 442 void force_signal_inject(int signal, int code, unsigned long address, unsigned long err)
 443 {
 444         const char *desc;
 445         struct pt_regs *regs = current_pt_regs();
 446
 447         if (WARN_ON(!user_mode(regs)))
 448                 return;
 449
 450         switch (signal) {
 451         case SIGILL:
 452                 desc = "undefined instruction";
 453                 break;
 454         case SIGSEGV:
 455                 desc = "illegal memory access";
 456                 break;
 457         default:
 458                 desc = "unknown or unrecoverable error";
 459                 break;
 460         }
 461
 462         /* Force signals we don't understand to SIGKILL */
 463         if (WARN_ON(signal != SIGKILL &&
 464                     siginfo_layout(signal, code) != SIL_FAULT)) {
 465                 signal = SIGKILL;
 466         }
 467
 468         arm64_notify_die(desc, regs, signal, code, address, err);
 469 }
 470
 471 /*
 472  * Set up process info to signal segmentation fault - called on access error.
 473  */
 474 void arm64_notify_segfault(unsigned long addr)
 475 {
 476         int code;
 477
 478         mmap_read_lock(current->mm);
 479         if (find_vma(current->mm, untagged_addr(addr)) == NULL)
 480                 code = SEGV_MAPERR;
 481         else
 482                 code = SEGV_ACCERR;
 483         mmap_read_unlock(current->mm);
 484
 485         force_signal_inject(SIGSEGV, code, addr, 0);
 486 }
 487
 488 void do_undefinstr(struct pt_regs *regs)
 489 {
 490         /* check for AArch32 breakpoint instructions */
 491         if (!aarch32_break_handler(regs))
 492                 return;
 493
 494         if (call_undef_hook(regs) == 0)
 495                 return;
 496
 497         BUG_ON(!user_mode(regs));
 498         force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
 499 }
 500 NOKPROBE_SYMBOL(do_undefinstr);
 501
 502 void do_bti(struct pt_regs *regs)
 503 {
 504         BUG_ON(!user_mode(regs));
 505         force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
 506 }
 507 NOKPROBE_SYMBOL(do_bti);
 508
 509 void do_ptrauth_fault(struct pt_regs *regs, unsigned long esr)
 510 {
 511         /*
 512          * Unexpected FPAC exception or pointer authentication failure in
 513          * the kernel: kill the task before it does any more harm.
 514          */
 515         BUG_ON(!user_mode(regs));
 516         force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr);
 517 }
 518 NOKPROBE_SYMBOL(do_ptrauth_fault);
 519
 520 #define __user_cache_maint(insn, address, res)                  \
 521         if (address >= TASK_SIZE_MAX) {                         \
 522                 res = -EFAULT;                                  \
 523         } else {                                                \
 524                 uaccess_ttbr0_enable();                         \
 525                 asm volatile (                                  \
 526                         "1:     " insn ", %1\n"                 \
 527                         "       mov     %w0, #0\n"              \
 528                         "2:\n"                                  \
 529                         _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0)   \
 530                         : "=r" (res)                            \
 531                         : "r" (address));                       \
 532                 uaccess_ttbr0_disable();                        \
 533         }
 534
 535 static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs)
 536 {
 537         unsigned long tagged_address, address;
 538         int rt = ESR_ELx_SYS64_ISS_RT(esr);
 539         int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT;
 540         int ret = 0;
 541
 542         tagged_address = pt_regs_read_reg(regs, rt);
 543         address = untagged_addr(tagged_address);
 544
 545         switch (crm) {
 546         case ESR_ELx_SYS64_ISS_CRM_DC_CVAU:     /* DC CVAU, gets promoted */
 547                 __user_cache_maint("dc civac", address, ret);
 548                 break;
 549         case ESR_ELx_SYS64_ISS_CRM_DC_CVAC:     /* DC CVAC, gets promoted */
 550                 __user_cache_maint("dc civac", address, ret);
 551                 break;
 552         case ESR_ELx_SYS64_ISS_CRM_DC_CVADP:    /* DC CVADP */
 553                 __user_cache_maint("sys 3, c7, c13, 1", address, ret);
 554                 break;
 555         case ESR_ELx_SYS64_ISS_CRM_DC_CVAP:     /* DC CVAP */
 556                 __user_cache_maint("sys 3, c7, c12, 1", address, ret);
 557                 break;
 558         case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC:    /* DC CIVAC */
 559                 __user_cache_maint("dc civac", address, ret);
 560                 break;
 561         case ESR_ELx_SYS64_ISS_CRM_IC_IVAU:     /* IC IVAU */
 562                 __user_cache_maint("ic ivau", address, ret);
 563                 break;
 564         default:
 565                 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
 566                 return;
 567         }
 568
 569         if (ret)
 570                 arm64_notify_segfault(tagged_address);
 571         else
 572                 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 573 }
 574
 575 static void ctr_read_handler(unsigned long esr, struct pt_regs *regs)
 576 {
 577         int rt = ESR_ELx_SYS64_ISS_RT(esr);
 578         unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0);
 579
 580         if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) {
 581                 /* Hide DIC so that we can trap the unnecessary maintenance...*/
 582                 val &= ~BIT(CTR_EL0_DIC_SHIFT);
 583
 584                 /* ... and fake IminLine to reduce the number of traps. */
 585                 val &= ~CTR_EL0_IminLine_MASK;
 586                 val |= (PAGE_SHIFT - 2) & CTR_EL0_IminLine_MASK;
 587         }
 588
 589         pt_regs_write_reg(regs, rt, val);
 590
 591         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 592 }
 593
 594 static void cntvct_read_handler(unsigned long esr, struct pt_regs *regs)
 595 {
 596         int rt = ESR_ELx_SYS64_ISS_RT(esr);
 597
 598         pt_regs_write_reg(regs, rt, arch_timer_read_counter());
 599         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 600 }
 601
 602 static void cntfrq_read_handler(unsigned long esr, struct pt_regs *regs)
 603 {
 604         int rt = ESR_ELx_SYS64_ISS_RT(esr);
 605
 606         pt_regs_write_reg(regs, rt, arch_timer_get_rate());
 607         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 608 }
 609
 610 static void mrs_handler(unsigned long esr, struct pt_regs *regs)
 611 {
 612         u32 sysreg, rt;
 613
 614         rt = ESR_ELx_SYS64_ISS_RT(esr);
 615         sysreg = esr_sys64_to_sysreg(esr);
 616
 617         if (do_emulate_mrs(regs, sysreg, rt) != 0)
 618                 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0);
 619 }
 620
 621 static void wfi_handler(unsigned long esr, struct pt_regs *regs)
 622 {
 623         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 624 }
 625
 626 struct sys64_hook {
 627         unsigned long esr_mask;
 628         unsigned long esr_val;
 629         void (*handler)(unsigned long esr, struct pt_regs *regs);
 630 };
 631
 632 static const struct sys64_hook sys64_hooks[] = {
 633         {
 634                 .esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK,
 635                 .esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL,
 636                 .handler = user_cache_maint_handler,
 637         },
 638         {
 639                 /* Trap read access to CTR_EL0 */
 640                 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
 641                 .esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ,
 642                 .handler = ctr_read_handler,
 643         },
 644         {
 645                 /* Trap read access to CNTVCT_EL0 */
 646                 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
 647                 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT,
 648                 .handler = cntvct_read_handler,
 649         },
 650         {
 651                 /* Trap read access to CNTVCTSS_EL0 */
 652                 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
 653                 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCTSS,
 654                 .handler = cntvct_read_handler,
 655         },
 656         {
 657                 /* Trap read access to CNTFRQ_EL0 */
 658                 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK,
 659                 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ,
 660                 .handler = cntfrq_read_handler,
 661         },
 662         {
 663                 /* Trap read access to CPUID registers */
 664                 .esr_mask = ESR_ELx_SYS64_ISS_SYS_MRS_OP_MASK,
 665                 .esr_val = ESR_ELx_SYS64_ISS_SYS_MRS_OP_VAL,
 666                 .handler = mrs_handler,
 667         },
 668         {
 669                 /* Trap WFI instructions executed in userspace */
 670                 .esr_mask = ESR_ELx_WFx_MASK,
 671                 .esr_val = ESR_ELx_WFx_WFI_VAL,
 672                 .handler = wfi_handler,
 673         },
 674         {},
 675 };
 676
 677 #ifdef CONFIG_COMPAT
 678 static bool cp15_cond_valid(unsigned long esr, struct pt_regs *regs)
 679 {
 680         int cond;
 681
 682         /* Only a T32 instruction can trap without CV being set */
 683         if (!(esr & ESR_ELx_CV)) {
 684                 u32 it;
 685
 686                 it = compat_get_it_state(regs);
 687                 if (!it)
 688                         return true;
 689
 690                 cond = it >> 4;
 691         } else {
 692                 cond = (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT;
 693         }
 694
 695         return aarch32_opcode_cond_checks[cond](regs->pstate);
 696 }
 697
 698 static void compat_cntfrq_read_handler(unsigned long esr, struct pt_regs *regs)
 699 {
 700         int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT;
 701
 702         pt_regs_write_reg(regs, reg, arch_timer_get_rate());
 703         arm64_skip_faulting_instruction(regs, 4);
 704 }
 705
 706 static const struct sys64_hook cp15_32_hooks[] = {
 707         {
 708                 .esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK,
 709                 .esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ,
 710                 .handler = compat_cntfrq_read_handler,
 711         },
 712         {},
 713 };
 714
 715 static void compat_cntvct_read_handler(unsigned long esr, struct pt_regs *regs)
 716 {
 717         int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT;
 718         int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT;
 719         u64 val = arch_timer_read_counter();
 720
 721         pt_regs_write_reg(regs, rt, lower_32_bits(val));
 722         pt_regs_write_reg(regs, rt2, upper_32_bits(val));
 723         arm64_skip_faulting_instruction(regs, 4);
 724 }
 725
 726 static const struct sys64_hook cp15_64_hooks[] = {
 727         {
 728                 .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK,
 729                 .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT,
 730                 .handler = compat_cntvct_read_handler,
 731         },
 732         {
 733                 .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK,
 734                 .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCTSS,
 735                 .handler = compat_cntvct_read_handler,
 736         },
 737         {},
 738 };
 739
 740 void do_cp15instr(unsigned long esr, struct pt_regs *regs)
 741 {
 742         const struct sys64_hook *hook, *hook_base;
 743
 744         if (!cp15_cond_valid(esr, regs)) {
 745                 /*
 746                  * There is no T16 variant of a CP access, so we
 747                  * always advance PC by 4 bytes.
 748                  */
 749                 arm64_skip_faulting_instruction(regs, 4);
 750                 return;
 751         }
 752
 753         switch (ESR_ELx_EC(esr)) {
 754         case ESR_ELx_EC_CP15_32:
 755                 hook_base = cp15_32_hooks;
 756                 break;
 757         case ESR_ELx_EC_CP15_64:
 758                 hook_base = cp15_64_hooks;
 759                 break;
 760         default:
 761                 do_undefinstr(regs);
 762                 return;
 763         }
 764
 765         for (hook = hook_base; hook->handler; hook++)
 766                 if ((hook->esr_mask & esr) == hook->esr_val) {
 767                         hook->handler(esr, regs);
 768                         return;
 769                 }
 770
 771         /*
 772          * New cp15 instructions may previously have been undefined at
 773          * EL0. Fall back to our usual undefined instruction handler
 774          * so that we handle these consistently.
 775          */
 776         do_undefinstr(regs);
 777 }
 778 NOKPROBE_SYMBOL(do_cp15instr);
 779 #endif
 780
 781 void do_sysinstr(unsigned long esr, struct pt_regs *regs)
 782 {
 783         const struct sys64_hook *hook;
 784
 785         for (hook = sys64_hooks; hook->handler; hook++)
 786                 if ((hook->esr_mask & esr) == hook->esr_val) {
 787                         hook->handler(esr, regs);
 788                         return;
 789                 }
 790
 791         /*
 792          * New SYS instructions may previously have been undefined at EL0. Fall
 793          * back to our usual undefined instruction handler so that we handle
 794          * these consistently.
 795          */
 796         do_undefinstr(regs);
 797 }
 798 NOKPROBE_SYMBOL(do_sysinstr);
 799
 800 static const char *esr_class_str[] = {
 801         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 802         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 803         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 804         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 805         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 806         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 807         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 808         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 809         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 810         [ESR_ELx_EC_PAC]                = "PAC",
 811         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 812         [ESR_ELx_EC_BTI]                = "BTI",
 813         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 814         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 815         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 816         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 817         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 818         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 819         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 820         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 821         [ESR_ELx_EC_SVE]                = "SVE",
 822         [ESR_ELx_EC_ERET]               = "ERET/ERETAA/ERETAB",
 823         [ESR_ELx_EC_FPAC]               = "FPAC",
 824         [ESR_ELx_EC_SME]                = "SME",
 825         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 826         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 827         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 828         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 829         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 830         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 831         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 832         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 833         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 834         [ESR_ELx_EC_SERROR]             = "SError",
 835         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 836         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 837         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 838         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 839         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 840         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 841         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 842         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 843         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 844 };
 845
 846 const char *esr_get_class_string(unsigned long esr)
 847 {
 848         return esr_class_str[ESR_ELx_EC(esr)];
 849 }
 850
 851 /*
 852  * bad_el0_sync handles unexpected, but potentially recoverable synchronous
 853  * exceptions taken from EL0.
 854  */
 855 void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr)
 856 {
 857         unsigned long pc = instruction_pointer(regs);
 858
 859         current->thread.fault_address = 0;
 860         current->thread.fault_code = esr;
 861
 862         arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc,
 863                               "Bad EL0 synchronous exception");
 864 }
 865
 866 #ifdef CONFIG_VMAP_STACK
 867
 868 DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack)
 869         __aligned(16);
 870
 871 void panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far)
 872 {
 873         unsigned long tsk_stk = (unsigned long)current->stack;
 874         unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
 875         unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack);
 876
 877         console_verbose();
 878         pr_emerg("Insufficient stack space to handle exception!");
 879
 880         pr_emerg("ESR: 0x%016lx -- %s\n", esr, esr_get_class_string(esr));
 881         pr_emerg("FAR: 0x%016lx\n", far);
 882
 883         pr_emerg("Task stack:     [0x%016lx..0x%016lx]\n",
 884                  tsk_stk, tsk_stk + THREAD_SIZE);
 885         pr_emerg("IRQ stack:      [0x%016lx..0x%016lx]\n",
 886                  irq_stk, irq_stk + IRQ_STACK_SIZE);
 887         pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n",
 888                  ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE);
 889
 890         __show_regs(regs);
 891
 892         /*
 893          * We use nmi_panic to limit the potential for recusive overflows, and
 894          * to get a better stack trace.
 895          */
 896         nmi_panic(NULL, "kernel stack overflow");
 897         cpu_park_loop();
 898 }
 899 #endif
 900
 901 void __noreturn arm64_serror_panic(struct pt_regs *regs, unsigned long esr)
 902 {
 903         console_verbose();
 904
 905         pr_crit("SError Interrupt on CPU%d, code 0x%016lx -- %s\n",
 906                 smp_processor_id(), esr, esr_get_class_string(esr));
 907         if (regs)
 908                 __show_regs(regs);
 909
 910         nmi_panic(regs, "Asynchronous SError Interrupt");
 911
 912         cpu_park_loop();
 913         unreachable();
 914 }
 915
 916 bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned long esr)
 917 {
 918         unsigned long aet = arm64_ras_serror_get_severity(esr);
 919
 920         switch (aet) {
 921         case ESR_ELx_AET_CE:    /* corrected error */
 922         case ESR_ELx_AET_UEO:   /* restartable, not yet consumed */
 923                 /*
 924                  * The CPU can make progress. We may take UEO again as
 925                  * a more severe error.
 926                  */
 927                 return false;
 928
 929         case ESR_ELx_AET_UEU:   /* Uncorrected Unrecoverable */
 930         case ESR_ELx_AET_UER:   /* Uncorrected Recoverable */
 931                 /*
 932                  * The CPU can't make progress. The exception may have
 933                  * been imprecise.
 934                  *
 935                  * Neoverse-N1 #1349291 means a non-KVM SError reported as
 936                  * Unrecoverable should be treated as Uncontainable. We
 937                  * call arm64_serror_panic() in both cases.
 938                  */
 939                 return true;
 940
 941         case ESR_ELx_AET_UC:    /* Uncontainable or Uncategorized error */
 942         default:
 943                 /* Error has been silently propagated */
 944                 arm64_serror_panic(regs, esr);
 945         }
 946 }
 947
 948 void do_serror(struct pt_regs *regs, unsigned long esr)
 949 {
 950         /* non-RAS errors are not containable */
 951         if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr))
 952                 arm64_serror_panic(regs, esr);
 953 }
 954
 955 /* GENERIC_BUG traps */
 956
 957 int is_valid_bugaddr(unsigned long addr)
 958 {
 959         /*
 960          * bug_handler() only called for BRK #BUG_BRK_IMM.
 961          * So the answer is trivial -- any spurious instances with no
 962          * bug table entry will be rejected by report_bug() and passed
 963          * back to the debug-monitors code and handled as a fatal
 964          * unexpected debug exception.
 965          */
 966         return 1;
 967 }
 968
 969 static int bug_handler(struct pt_regs *regs, unsigned long esr)
 970 {
 971         switch (report_bug(regs->pc, regs)) {
 972         case BUG_TRAP_TYPE_BUG:
 973                 die("Oops - BUG", regs, 0);
 974                 break;
 975
 976         case BUG_TRAP_TYPE_WARN:
 977                 break;
 978
 979         default:
 980                 /* unknown/unrecognised bug trap type */
 981                 return DBG_HOOK_ERROR;
 982         }
 983
 984         /* If thread survives, skip over the BUG instruction and continue: */
 985         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
 986         return DBG_HOOK_HANDLED;
 987 }
 988
 989 static struct break_hook bug_break_hook = {
 990         .fn = bug_handler,
 991         .imm = BUG_BRK_IMM,
 992 };
 993
 994 static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr)
 995 {
 996         pr_err("%s generated an invalid instruction at %pS!\n",
 997                 "Kernel text patching",
 998                 (void *)instruction_pointer(regs));
 999
1000         /* We cannot handle this */
1001         return DBG_HOOK_ERROR;
1002 }
1003
1004 static struct break_hook fault_break_hook = {
1005         .fn = reserved_fault_handler,
1006         .imm = FAULT_BRK_IMM,
1007 };
1008
1009 #ifdef CONFIG_KASAN_SW_TAGS
1010
1011 #define KASAN_ESR_RECOVER       0x20
1012 #define KASAN_ESR_WRITE 0x10
1013 #define KASAN_ESR_SIZE_MASK     0x0f
1014 #define KASAN_ESR_SIZE(esr)     (1 << ((esr) & KASAN_ESR_SIZE_MASK))
1015
1016 static int kasan_handler(struct pt_regs *regs, unsigned long esr)
1017 {
1018         bool recover = esr & KASAN_ESR_RECOVER;
1019         bool write = esr & KASAN_ESR_WRITE;
1020         size_t size = KASAN_ESR_SIZE(esr);
1021         u64 addr = regs->regs[0];
1022         u64 pc = regs->pc;
1023
1024         kasan_report(addr, size, write, pc);
1025
1026         /*
1027          * The instrumentation allows to control whether we can proceed after
1028          * a crash was detected. This is done by passing the -recover flag to
1029          * the compiler. Disabling recovery allows to generate more compact
1030          * code.
1031          *
1032          * Unfortunately disabling recovery doesn't work for the kernel right
1033          * now. KASAN reporting is disabled in some contexts (for example when
1034          * the allocator accesses slab object metadata; this is controlled by
1035          * current->kasan_depth). All these accesses are detected by the tool,
1036          * even though the reports for them are not printed.
1037          *
1038          * This is something that might be fixed at some point in the future.
1039          */
1040         if (!recover)
1041                 die("Oops - KASAN", regs, 0);
1042
1043         /* If thread survives, skip over the brk instruction and continue: */
1044         arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
1045         return DBG_HOOK_HANDLED;
1046 }
1047
1048 static struct break_hook kasan_break_hook = {
1049         .fn     = kasan_handler,
1050         .imm    = KASAN_BRK_IMM,
1051         .mask   = KASAN_BRK_MASK,
1052 };
1053 #endif
1054
1055 /*
1056  * Initial handler for AArch64 BRK exceptions
1057  * This handler only used until debug_traps_init().
1058  */
1059 int __init early_brk64(unsigned long addr, unsigned long esr,
1060                 struct pt_regs *regs)
1061 {
1062 #ifdef CONFIG_KASAN_SW_TAGS
1063         unsigned long comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK;
1064
1065         if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM)
1066                 return kasan_handler(regs, esr) != DBG_HOOK_HANDLED;
1067 #endif
1068         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
1069 }
1070
1071 void __init trap_init(void)
1072 {
1073         register_kernel_break_hook(&bug_break_hook);
1074         register_kernel_break_hook(&fault_break_hook);
1075 #ifdef CONFIG_KASAN_SW_TAGS
1076         register_kernel_break_hook(&kasan_break_hook);
1077 #endif
1078         debug_traps_init();
1079 }