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/personality.h> 13 #include <linux/kallsyms.h> 14 #include <linux/kprobes.h> 15 #include <linux/spinlock.h> 16 #include <linux/uaccess.h> 17 #include <linux/hardirq.h> 18 #include <linux/kdebug.h> 19 #include <linux/module.h> 20 #include <linux/kexec.h> 21 #include <linux/delay.h> 22 #include <linux/init.h> 23 #include <linux/sched/signal.h> 24 #include <linux/sched/debug.h> 25 #include <linux/sched/task_stack.h> 26 #include <linux/sizes.h> 27 #include <linux/syscalls.h> 28 #include <linux/mm_types.h> 29 #include <linux/kasan.h> 30 31 #include <asm/atomic.h> 32 #include <asm/bug.h> 33 #include <asm/cpufeature.h> 34 #include <asm/daifflags.h> 35 #include <asm/debug-monitors.h> 36 #include <asm/esr.h> 37 #include <asm/extable.h> 38 #include <asm/insn.h> 39 #include <asm/kprobes.h> 40 #include <asm/traps.h> 41 #include <asm/smp.h> 42 #include <asm/stack_pointer.h> 43 #include <asm/stacktrace.h> 44 #include <asm/exception.h> 45 #include <asm/system_misc.h> 46 #include <asm/sysreg.h> 47 48 static const char *handler[]= { 49 "Synchronous Abort", 50 "IRQ", 51 "FIQ", 52 "Error" 53 }; 54 55 int show_unhandled_signals = 0; 56 57 static void dump_kernel_instr(const char *lvl, struct pt_regs *regs) 58 { 59 unsigned long addr = instruction_pointer(regs); 60 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; 61 int i; 62 63 if (user_mode(regs)) 64 return; 65 66 for (i = -4; i < 1; i++) { 67 unsigned int val, bad; 68 69 bad = aarch64_insn_read(&((u32 *)addr)[i], &val); 70 71 if (!bad) 72 p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val); 73 else { 74 p += sprintf(p, "bad PC value"); 75 break; 76 } 77 } 78 79 printk("%sCode: %s\n", lvl, str); 80 } 81 82 #ifdef CONFIG_PREEMPT 83 #define S_PREEMPT " PREEMPT" 84 #elif defined(CONFIG_PREEMPT_RT) 85 #define S_PREEMPT " PREEMPT_RT" 86 #else 87 #define S_PREEMPT "" 88 #endif 89 90 #define S_SMP " SMP" 91 92 static int __die(const char *str, int err, struct pt_regs *regs) 93 { 94 static int die_counter; 95 int ret; 96 97 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n", 98 str, err, ++die_counter); 99 100 /* trap and error numbers are mostly meaningless on ARM */ 101 ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV); 102 if (ret == NOTIFY_STOP) 103 return ret; 104 105 print_modules(); 106 show_regs(regs); 107 108 dump_kernel_instr(KERN_EMERG, regs); 109 110 return ret; 111 } 112 113 static DEFINE_RAW_SPINLOCK(die_lock); 114 115 /* 116 * This function is protected against re-entrancy. 117 */ 118 void die(const char *str, struct pt_regs *regs, int err) 119 { 120 int ret; 121 unsigned long flags; 122 123 raw_spin_lock_irqsave(&die_lock, flags); 124 125 oops_enter(); 126 127 console_verbose(); 128 bust_spinlocks(1); 129 ret = __die(str, err, regs); 130 131 if (regs && kexec_should_crash(current)) 132 crash_kexec(regs); 133 134 bust_spinlocks(0); 135 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 136 oops_exit(); 137 138 if (in_interrupt()) 139 panic("%s: Fatal exception in interrupt", str); 140 if (panic_on_oops) 141 panic("%s: Fatal exception", str); 142 143 raw_spin_unlock_irqrestore(&die_lock, flags); 144 145 if (ret != NOTIFY_STOP) 146 do_exit(SIGSEGV); 147 } 148 149 static void arm64_show_signal(int signo, const char *str) 150 { 151 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, 152 DEFAULT_RATELIMIT_BURST); 153 struct task_struct *tsk = current; 154 unsigned int esr = tsk->thread.fault_code; 155 struct pt_regs *regs = task_pt_regs(tsk); 156 157 /* Leave if the signal won't be shown */ 158 if (!show_unhandled_signals || 159 !unhandled_signal(tsk, signo) || 160 !__ratelimit(&rs)) 161 return; 162 163 pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk)); 164 if (esr) 165 pr_cont("%s, ESR 0x%08x, ", esr_get_class_string(esr), esr); 166 167 pr_cont("%s", str); 168 print_vma_addr(KERN_CONT " in ", regs->pc); 169 pr_cont("\n"); 170 __show_regs(regs); 171 } 172 173 void arm64_force_sig_fault(int signo, int code, void __user *addr, 174 const char *str) 175 { 176 arm64_show_signal(signo, str); 177 if (signo == SIGKILL) 178 force_sig(SIGKILL); 179 else 180 force_sig_fault(signo, code, addr); 181 } 182 183 void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, 184 const char *str) 185 { 186 arm64_show_signal(SIGBUS, str); 187 force_sig_mceerr(code, addr, lsb); 188 } 189 190 void arm64_force_sig_ptrace_errno_trap(int errno, void __user *addr, 191 const char *str) 192 { 193 arm64_show_signal(SIGTRAP, str); 194 force_sig_ptrace_errno_trap(errno, addr); 195 } 196 197 void arm64_notify_die(const char *str, struct pt_regs *regs, 198 int signo, int sicode, void __user *addr, 199 int err) 200 { 201 if (user_mode(regs)) { 202 WARN_ON(regs != current_pt_regs()); 203 current->thread.fault_address = 0; 204 current->thread.fault_code = err; 205 206 arm64_force_sig_fault(signo, sicode, addr, str); 207 } else { 208 die(str, regs, err); 209 } 210 } 211 212 #ifdef CONFIG_COMPAT 213 #define PSTATE_IT_1_0_SHIFT 25 214 #define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT) 215 #define PSTATE_IT_7_2_SHIFT 10 216 #define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT) 217 218 static u32 compat_get_it_state(struct pt_regs *regs) 219 { 220 u32 it, pstate = regs->pstate; 221 222 it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT; 223 it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2; 224 225 return it; 226 } 227 228 static void compat_set_it_state(struct pt_regs *regs, u32 it) 229 { 230 u32 pstate_it; 231 232 pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK; 233 pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK; 234 235 regs->pstate &= ~PSR_AA32_IT_MASK; 236 regs->pstate |= pstate_it; 237 } 238 239 static void advance_itstate(struct pt_regs *regs) 240 { 241 u32 it; 242 243 /* ARM mode */ 244 if (!(regs->pstate & PSR_AA32_T_BIT) || 245 !(regs->pstate & PSR_AA32_IT_MASK)) 246 return; 247 248 it = compat_get_it_state(regs); 249 250 /* 251 * If this is the last instruction of the block, wipe the IT 252 * state. Otherwise advance it. 253 */ 254 if (!(it & 7)) 255 it = 0; 256 else 257 it = (it & 0xe0) | ((it << 1) & 0x1f); 258 259 compat_set_it_state(regs, it); 260 } 261 #else 262 static void advance_itstate(struct pt_regs *regs) 263 { 264 } 265 #endif 266 267 void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) 268 { 269 regs->pc += size; 270 271 /* 272 * If we were single stepping, we want to get the step exception after 273 * we return from the trap. 274 */ 275 if (user_mode(regs)) 276 user_fastforward_single_step(current); 277 278 if (compat_user_mode(regs)) 279 advance_itstate(regs); 280 else 281 regs->pstate &= ~PSR_BTYPE_MASK; 282 } 283 284 static LIST_HEAD(undef_hook); 285 static DEFINE_RAW_SPINLOCK(undef_lock); 286 287 void register_undef_hook(struct undef_hook *hook) 288 { 289 unsigned long flags; 290 291 raw_spin_lock_irqsave(&undef_lock, flags); 292 list_add(&hook->node, &undef_hook); 293 raw_spin_unlock_irqrestore(&undef_lock, flags); 294 } 295 296 void unregister_undef_hook(struct undef_hook *hook) 297 { 298 unsigned long flags; 299 300 raw_spin_lock_irqsave(&undef_lock, flags); 301 list_del(&hook->node); 302 raw_spin_unlock_irqrestore(&undef_lock, flags); 303 } 304 305 static int call_undef_hook(struct pt_regs *regs) 306 { 307 struct undef_hook *hook; 308 unsigned long flags; 309 u32 instr; 310 int (*fn)(struct pt_regs *regs, u32 instr) = NULL; 311 void __user *pc = (void __user *)instruction_pointer(regs); 312 313 if (!user_mode(regs)) { 314 __le32 instr_le; 315 if (get_kernel_nofault(instr_le, (__force __le32 *)pc)) 316 goto exit; 317 instr = le32_to_cpu(instr_le); 318 } else if (compat_thumb_mode(regs)) { 319 /* 16-bit Thumb instruction */ 320 __le16 instr_le; 321 if (get_user(instr_le, (__le16 __user *)pc)) 322 goto exit; 323 instr = le16_to_cpu(instr_le); 324 if (aarch32_insn_is_wide(instr)) { 325 u32 instr2; 326 327 if (get_user(instr_le, (__le16 __user *)(pc + 2))) 328 goto exit; 329 instr2 = le16_to_cpu(instr_le); 330 instr = (instr << 16) | instr2; 331 } 332 } else { 333 /* 32-bit ARM instruction */ 334 __le32 instr_le; 335 if (get_user(instr_le, (__le32 __user *)pc)) 336 goto exit; 337 instr = le32_to_cpu(instr_le); 338 } 339 340 raw_spin_lock_irqsave(&undef_lock, flags); 341 list_for_each_entry(hook, &undef_hook, node) 342 if ((instr & hook->instr_mask) == hook->instr_val && 343 (regs->pstate & hook->pstate_mask) == hook->pstate_val) 344 fn = hook->fn; 345 346 raw_spin_unlock_irqrestore(&undef_lock, flags); 347 exit: 348 return fn ? fn(regs, instr) : 1; 349 } 350 351 void force_signal_inject(int signal, int code, unsigned long address, unsigned int err) 352 { 353 const char *desc; 354 struct pt_regs *regs = current_pt_regs(); 355 356 if (WARN_ON(!user_mode(regs))) 357 return; 358 359 switch (signal) { 360 case SIGILL: 361 desc = "undefined instruction"; 362 break; 363 case SIGSEGV: 364 desc = "illegal memory access"; 365 break; 366 default: 367 desc = "unknown or unrecoverable error"; 368 break; 369 } 370 371 /* Force signals we don't understand to SIGKILL */ 372 if (WARN_ON(signal != SIGKILL && 373 siginfo_layout(signal, code) != SIL_FAULT)) { 374 signal = SIGKILL; 375 } 376 377 arm64_notify_die(desc, regs, signal, code, (void __user *)address, err); 378 } 379 380 /* 381 * Set up process info to signal segmentation fault - called on access error. 382 */ 383 void arm64_notify_segfault(unsigned long addr) 384 { 385 int code; 386 387 mmap_read_lock(current->mm); 388 if (find_vma(current->mm, addr) == NULL) 389 code = SEGV_MAPERR; 390 else 391 code = SEGV_ACCERR; 392 mmap_read_unlock(current->mm); 393 394 force_signal_inject(SIGSEGV, code, addr, 0); 395 } 396 397 void do_undefinstr(struct pt_regs *regs) 398 { 399 /* check for AArch32 breakpoint instructions */ 400 if (!aarch32_break_handler(regs)) 401 return; 402 403 if (call_undef_hook(regs) == 0) 404 return; 405 406 BUG_ON(!user_mode(regs)); 407 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 408 } 409 NOKPROBE_SYMBOL(do_undefinstr); 410 411 void do_bti(struct pt_regs *regs) 412 { 413 BUG_ON(!user_mode(regs)); 414 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 415 } 416 NOKPROBE_SYMBOL(do_bti); 417 418 void do_ptrauth_fault(struct pt_regs *regs, unsigned int esr) 419 { 420 /* 421 * Unexpected FPAC exception or pointer authentication failure in 422 * the kernel: kill the task before it does any more harm. 423 */ 424 BUG_ON(!user_mode(regs)); 425 force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); 426 } 427 NOKPROBE_SYMBOL(do_ptrauth_fault); 428 429 #define __user_cache_maint(insn, address, res) \ 430 if (address >= user_addr_max()) { \ 431 res = -EFAULT; \ 432 } else { \ 433 uaccess_ttbr0_enable(); \ 434 asm volatile ( \ 435 "1: " insn ", %1\n" \ 436 " mov %w0, #0\n" \ 437 "2:\n" \ 438 " .pushsection .fixup,\"ax\"\n" \ 439 " .align 2\n" \ 440 "3: mov %w0, %w2\n" \ 441 " b 2b\n" \ 442 " .popsection\n" \ 443 _ASM_EXTABLE(1b, 3b) \ 444 : "=r" (res) \ 445 : "r" (address), "i" (-EFAULT)); \ 446 uaccess_ttbr0_disable(); \ 447 } 448 449 static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) 450 { 451 unsigned long address; 452 int rt = ESR_ELx_SYS64_ISS_RT(esr); 453 int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; 454 int ret = 0; 455 456 address = untagged_addr(pt_regs_read_reg(regs, rt)); 457 458 switch (crm) { 459 case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ 460 __user_cache_maint("dc civac", address, ret); 461 break; 462 case ESR_ELx_SYS64_ISS_CRM_DC_CVAC: /* DC CVAC, gets promoted */ 463 __user_cache_maint("dc civac", address, ret); 464 break; 465 case ESR_ELx_SYS64_ISS_CRM_DC_CVADP: /* DC CVADP */ 466 __user_cache_maint("sys 3, c7, c13, 1", address, ret); 467 break; 468 case ESR_ELx_SYS64_ISS_CRM_DC_CVAP: /* DC CVAP */ 469 __user_cache_maint("sys 3, c7, c12, 1", address, ret); 470 break; 471 case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC: /* DC CIVAC */ 472 __user_cache_maint("dc civac", address, ret); 473 break; 474 case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */ 475 __user_cache_maint("ic ivau", address, ret); 476 break; 477 default: 478 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 479 return; 480 } 481 482 if (ret) 483 arm64_notify_segfault(address); 484 else 485 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 486 } 487 488 static void ctr_read_handler(unsigned int esr, struct pt_regs *regs) 489 { 490 int rt = ESR_ELx_SYS64_ISS_RT(esr); 491 unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); 492 493 if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { 494 /* Hide DIC so that we can trap the unnecessary maintenance...*/ 495 val &= ~BIT(CTR_DIC_SHIFT); 496 497 /* ... and fake IminLine to reduce the number of traps. */ 498 val &= ~CTR_IMINLINE_MASK; 499 val |= (PAGE_SHIFT - 2) & CTR_IMINLINE_MASK; 500 } 501 502 pt_regs_write_reg(regs, rt, val); 503 504 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 505 } 506 507 static void cntvct_read_handler(unsigned int esr, struct pt_regs *regs) 508 { 509 int rt = ESR_ELx_SYS64_ISS_RT(esr); 510 511 pt_regs_write_reg(regs, rt, arch_timer_read_counter()); 512 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 513 } 514 515 static void cntfrq_read_handler(unsigned int esr, struct pt_regs *regs) 516 { 517 int rt = ESR_ELx_SYS64_ISS_RT(esr); 518 519 pt_regs_write_reg(regs, rt, arch_timer_get_rate()); 520 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 521 } 522 523 static void mrs_handler(unsigned int esr, struct pt_regs *regs) 524 { 525 u32 sysreg, rt; 526 527 rt = ESR_ELx_SYS64_ISS_RT(esr); 528 sysreg = esr_sys64_to_sysreg(esr); 529 530 if (do_emulate_mrs(regs, sysreg, rt) != 0) 531 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 532 } 533 534 static void wfi_handler(unsigned int esr, struct pt_regs *regs) 535 { 536 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 537 } 538 539 struct sys64_hook { 540 unsigned int esr_mask; 541 unsigned int esr_val; 542 void (*handler)(unsigned int esr, struct pt_regs *regs); 543 }; 544 545 static const struct sys64_hook sys64_hooks[] = { 546 { 547 .esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK, 548 .esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL, 549 .handler = user_cache_maint_handler, 550 }, 551 { 552 /* Trap read access to CTR_EL0 */ 553 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 554 .esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ, 555 .handler = ctr_read_handler, 556 }, 557 { 558 /* Trap read access to CNTVCT_EL0 */ 559 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 560 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, 561 .handler = cntvct_read_handler, 562 }, 563 { 564 /* Trap read access to CNTFRQ_EL0 */ 565 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 566 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ, 567 .handler = cntfrq_read_handler, 568 }, 569 { 570 /* Trap read access to CPUID registers */ 571 .esr_mask = ESR_ELx_SYS64_ISS_SYS_MRS_OP_MASK, 572 .esr_val = ESR_ELx_SYS64_ISS_SYS_MRS_OP_VAL, 573 .handler = mrs_handler, 574 }, 575 { 576 /* Trap WFI instructions executed in userspace */ 577 .esr_mask = ESR_ELx_WFx_MASK, 578 .esr_val = ESR_ELx_WFx_WFI_VAL, 579 .handler = wfi_handler, 580 }, 581 {}, 582 }; 583 584 #ifdef CONFIG_COMPAT 585 static bool cp15_cond_valid(unsigned int esr, struct pt_regs *regs) 586 { 587 int cond; 588 589 /* Only a T32 instruction can trap without CV being set */ 590 if (!(esr & ESR_ELx_CV)) { 591 u32 it; 592 593 it = compat_get_it_state(regs); 594 if (!it) 595 return true; 596 597 cond = it >> 4; 598 } else { 599 cond = (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT; 600 } 601 602 return aarch32_opcode_cond_checks[cond](regs->pstate); 603 } 604 605 static void compat_cntfrq_read_handler(unsigned int esr, struct pt_regs *regs) 606 { 607 int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT; 608 609 pt_regs_write_reg(regs, reg, arch_timer_get_rate()); 610 arm64_skip_faulting_instruction(regs, 4); 611 } 612 613 static const struct sys64_hook cp15_32_hooks[] = { 614 { 615 .esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK, 616 .esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ, 617 .handler = compat_cntfrq_read_handler, 618 }, 619 {}, 620 }; 621 622 static void compat_cntvct_read_handler(unsigned int esr, struct pt_regs *regs) 623 { 624 int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT; 625 int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT; 626 u64 val = arch_timer_read_counter(); 627 628 pt_regs_write_reg(regs, rt, lower_32_bits(val)); 629 pt_regs_write_reg(regs, rt2, upper_32_bits(val)); 630 arm64_skip_faulting_instruction(regs, 4); 631 } 632 633 static const struct sys64_hook cp15_64_hooks[] = { 634 { 635 .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, 636 .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT, 637 .handler = compat_cntvct_read_handler, 638 }, 639 {}, 640 }; 641 642 void do_cp15instr(unsigned int esr, struct pt_regs *regs) 643 { 644 const struct sys64_hook *hook, *hook_base; 645 646 if (!cp15_cond_valid(esr, regs)) { 647 /* 648 * There is no T16 variant of a CP access, so we 649 * always advance PC by 4 bytes. 650 */ 651 arm64_skip_faulting_instruction(regs, 4); 652 return; 653 } 654 655 switch (ESR_ELx_EC(esr)) { 656 case ESR_ELx_EC_CP15_32: 657 hook_base = cp15_32_hooks; 658 break; 659 case ESR_ELx_EC_CP15_64: 660 hook_base = cp15_64_hooks; 661 break; 662 default: 663 do_undefinstr(regs); 664 return; 665 } 666 667 for (hook = hook_base; hook->handler; hook++) 668 if ((hook->esr_mask & esr) == hook->esr_val) { 669 hook->handler(esr, regs); 670 return; 671 } 672 673 /* 674 * New cp15 instructions may previously have been undefined at 675 * EL0. Fall back to our usual undefined instruction handler 676 * so that we handle these consistently. 677 */ 678 do_undefinstr(regs); 679 } 680 NOKPROBE_SYMBOL(do_cp15instr); 681 #endif 682 683 void do_sysinstr(unsigned int esr, struct pt_regs *regs) 684 { 685 const struct sys64_hook *hook; 686 687 for (hook = sys64_hooks; hook->handler; hook++) 688 if ((hook->esr_mask & esr) == hook->esr_val) { 689 hook->handler(esr, regs); 690 return; 691 } 692 693 /* 694 * New SYS instructions may previously have been undefined at EL0. Fall 695 * back to our usual undefined instruction handler so that we handle 696 * these consistently. 697 */ 698 do_undefinstr(regs); 699 } 700 NOKPROBE_SYMBOL(do_sysinstr); 701 702 static const char *esr_class_str[] = { 703 [0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC", 704 [ESR_ELx_EC_UNKNOWN] = "Unknown/Uncategorized", 705 [ESR_ELx_EC_WFx] = "WFI/WFE", 706 [ESR_ELx_EC_CP15_32] = "CP15 MCR/MRC", 707 [ESR_ELx_EC_CP15_64] = "CP15 MCRR/MRRC", 708 [ESR_ELx_EC_CP14_MR] = "CP14 MCR/MRC", 709 [ESR_ELx_EC_CP14_LS] = "CP14 LDC/STC", 710 [ESR_ELx_EC_FP_ASIMD] = "ASIMD", 711 [ESR_ELx_EC_CP10_ID] = "CP10 MRC/VMRS", 712 [ESR_ELx_EC_PAC] = "PAC", 713 [ESR_ELx_EC_CP14_64] = "CP14 MCRR/MRRC", 714 [ESR_ELx_EC_BTI] = "BTI", 715 [ESR_ELx_EC_ILL] = "PSTATE.IL", 716 [ESR_ELx_EC_SVC32] = "SVC (AArch32)", 717 [ESR_ELx_EC_HVC32] = "HVC (AArch32)", 718 [ESR_ELx_EC_SMC32] = "SMC (AArch32)", 719 [ESR_ELx_EC_SVC64] = "SVC (AArch64)", 720 [ESR_ELx_EC_HVC64] = "HVC (AArch64)", 721 [ESR_ELx_EC_SMC64] = "SMC (AArch64)", 722 [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)", 723 [ESR_ELx_EC_SVE] = "SVE", 724 [ESR_ELx_EC_ERET] = "ERET/ERETAA/ERETAB", 725 [ESR_ELx_EC_FPAC] = "FPAC", 726 [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF", 727 [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)", 728 [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)", 729 [ESR_ELx_EC_PC_ALIGN] = "PC Alignment", 730 [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", 731 [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", 732 [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", 733 [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", 734 [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", 735 [ESR_ELx_EC_SERROR] = "SError", 736 [ESR_ELx_EC_BREAKPT_LOW] = "Breakpoint (lower EL)", 737 [ESR_ELx_EC_BREAKPT_CUR] = "Breakpoint (current EL)", 738 [ESR_ELx_EC_SOFTSTP_LOW] = "Software Step (lower EL)", 739 [ESR_ELx_EC_SOFTSTP_CUR] = "Software Step (current EL)", 740 [ESR_ELx_EC_WATCHPT_LOW] = "Watchpoint (lower EL)", 741 [ESR_ELx_EC_WATCHPT_CUR] = "Watchpoint (current EL)", 742 [ESR_ELx_EC_BKPT32] = "BKPT (AArch32)", 743 [ESR_ELx_EC_VECTOR32] = "Vector catch (AArch32)", 744 [ESR_ELx_EC_BRK64] = "BRK (AArch64)", 745 }; 746 747 const char *esr_get_class_string(u32 esr) 748 { 749 return esr_class_str[ESR_ELx_EC(esr)]; 750 } 751 752 /* 753 * bad_mode handles the impossible case in the exception vector. This is always 754 * fatal. 755 */ 756 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr) 757 { 758 console_verbose(); 759 760 pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n", 761 handler[reason], smp_processor_id(), esr, 762 esr_get_class_string(esr)); 763 764 __show_regs(regs); 765 local_daif_mask(); 766 panic("bad mode"); 767 } 768 769 /* 770 * bad_el0_sync handles unexpected, but potentially recoverable synchronous 771 * exceptions taken from EL0. Unlike bad_mode, this returns. 772 */ 773 void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr) 774 { 775 void __user *pc = (void __user *)instruction_pointer(regs); 776 777 current->thread.fault_address = 0; 778 current->thread.fault_code = esr; 779 780 arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, 781 "Bad EL0 synchronous exception"); 782 } 783 784 #ifdef CONFIG_VMAP_STACK 785 786 DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack) 787 __aligned(16); 788 789 asmlinkage void handle_bad_stack(struct pt_regs *regs) 790 { 791 unsigned long tsk_stk = (unsigned long)current->stack; 792 unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr); 793 unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); 794 unsigned int esr = read_sysreg(esr_el1); 795 unsigned long far = read_sysreg(far_el1); 796 797 console_verbose(); 798 pr_emerg("Insufficient stack space to handle exception!"); 799 800 pr_emerg("ESR: 0x%08x -- %s\n", esr, esr_get_class_string(esr)); 801 pr_emerg("FAR: 0x%016lx\n", far); 802 803 pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", 804 tsk_stk, tsk_stk + THREAD_SIZE); 805 pr_emerg("IRQ stack: [0x%016lx..0x%016lx]\n", 806 irq_stk, irq_stk + IRQ_STACK_SIZE); 807 pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", 808 ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); 809 810 __show_regs(regs); 811 812 /* 813 * We use nmi_panic to limit the potential for recusive overflows, and 814 * to get a better stack trace. 815 */ 816 nmi_panic(NULL, "kernel stack overflow"); 817 cpu_park_loop(); 818 } 819 #endif 820 821 void __noreturn arm64_serror_panic(struct pt_regs *regs, u32 esr) 822 { 823 console_verbose(); 824 825 pr_crit("SError Interrupt on CPU%d, code 0x%08x -- %s\n", 826 smp_processor_id(), esr, esr_get_class_string(esr)); 827 if (regs) 828 __show_regs(regs); 829 830 nmi_panic(regs, "Asynchronous SError Interrupt"); 831 832 cpu_park_loop(); 833 unreachable(); 834 } 835 836 bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned int esr) 837 { 838 u32 aet = arm64_ras_serror_get_severity(esr); 839 840 switch (aet) { 841 case ESR_ELx_AET_CE: /* corrected error */ 842 case ESR_ELx_AET_UEO: /* restartable, not yet consumed */ 843 /* 844 * The CPU can make progress. We may take UEO again as 845 * a more severe error. 846 */ 847 return false; 848 849 case ESR_ELx_AET_UEU: /* Uncorrected Unrecoverable */ 850 case ESR_ELx_AET_UER: /* Uncorrected Recoverable */ 851 /* 852 * The CPU can't make progress. The exception may have 853 * been imprecise. 854 * 855 * Neoverse-N1 #1349291 means a non-KVM SError reported as 856 * Unrecoverable should be treated as Uncontainable. We 857 * call arm64_serror_panic() in both cases. 858 */ 859 return true; 860 861 case ESR_ELx_AET_UC: /* Uncontainable or Uncategorized error */ 862 default: 863 /* Error has been silently propagated */ 864 arm64_serror_panic(regs, esr); 865 } 866 } 867 868 asmlinkage void do_serror(struct pt_regs *regs, unsigned int esr) 869 { 870 nmi_enter(); 871 872 /* non-RAS errors are not containable */ 873 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr)) 874 arm64_serror_panic(regs, esr); 875 876 nmi_exit(); 877 } 878 879 asmlinkage void enter_from_user_mode(void) 880 { 881 CT_WARN_ON(ct_state() != CONTEXT_USER); 882 user_exit_irqoff(); 883 } 884 NOKPROBE_SYMBOL(enter_from_user_mode); 885 886 /* GENERIC_BUG traps */ 887 888 int is_valid_bugaddr(unsigned long addr) 889 { 890 /* 891 * bug_handler() only called for BRK #BUG_BRK_IMM. 892 * So the answer is trivial -- any spurious instances with no 893 * bug table entry will be rejected by report_bug() and passed 894 * back to the debug-monitors code and handled as a fatal 895 * unexpected debug exception. 896 */ 897 return 1; 898 } 899 900 static int bug_handler(struct pt_regs *regs, unsigned int esr) 901 { 902 switch (report_bug(regs->pc, regs)) { 903 case BUG_TRAP_TYPE_BUG: 904 die("Oops - BUG", regs, 0); 905 break; 906 907 case BUG_TRAP_TYPE_WARN: 908 break; 909 910 default: 911 /* unknown/unrecognised bug trap type */ 912 return DBG_HOOK_ERROR; 913 } 914 915 /* If thread survives, skip over the BUG instruction and continue: */ 916 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 917 return DBG_HOOK_HANDLED; 918 } 919 920 static struct break_hook bug_break_hook = { 921 .fn = bug_handler, 922 .imm = BUG_BRK_IMM, 923 }; 924 925 static int reserved_fault_handler(struct pt_regs *regs, unsigned int esr) 926 { 927 pr_err("%s generated an invalid instruction at %pS!\n", 928 in_bpf_jit(regs) ? "BPF JIT" : "Kernel text patching", 929 (void *)instruction_pointer(regs)); 930 931 /* We cannot handle this */ 932 return DBG_HOOK_ERROR; 933 } 934 935 static struct break_hook fault_break_hook = { 936 .fn = reserved_fault_handler, 937 .imm = FAULT_BRK_IMM, 938 }; 939 940 #ifdef CONFIG_KASAN_SW_TAGS 941 942 #define KASAN_ESR_RECOVER 0x20 943 #define KASAN_ESR_WRITE 0x10 944 #define KASAN_ESR_SIZE_MASK 0x0f 945 #define KASAN_ESR_SIZE(esr) (1 << ((esr) & KASAN_ESR_SIZE_MASK)) 946 947 static int kasan_handler(struct pt_regs *regs, unsigned int esr) 948 { 949 bool recover = esr & KASAN_ESR_RECOVER; 950 bool write = esr & KASAN_ESR_WRITE; 951 size_t size = KASAN_ESR_SIZE(esr); 952 u64 addr = regs->regs[0]; 953 u64 pc = regs->pc; 954 955 kasan_report(addr, size, write, pc); 956 957 /* 958 * The instrumentation allows to control whether we can proceed after 959 * a crash was detected. This is done by passing the -recover flag to 960 * the compiler. Disabling recovery allows to generate more compact 961 * code. 962 * 963 * Unfortunately disabling recovery doesn't work for the kernel right 964 * now. KASAN reporting is disabled in some contexts (for example when 965 * the allocator accesses slab object metadata; this is controlled by 966 * current->kasan_depth). All these accesses are detected by the tool, 967 * even though the reports for them are not printed. 968 * 969 * This is something that might be fixed at some point in the future. 970 */ 971 if (!recover) 972 die("Oops - KASAN", regs, 0); 973 974 /* If thread survives, skip over the brk instruction and continue: */ 975 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 976 return DBG_HOOK_HANDLED; 977 } 978 979 static struct break_hook kasan_break_hook = { 980 .fn = kasan_handler, 981 .imm = KASAN_BRK_IMM, 982 .mask = KASAN_BRK_MASK, 983 }; 984 #endif 985 986 /* 987 * Initial handler for AArch64 BRK exceptions 988 * This handler only used until debug_traps_init(). 989 */ 990 int __init early_brk64(unsigned long addr, unsigned int esr, 991 struct pt_regs *regs) 992 { 993 #ifdef CONFIG_KASAN_SW_TAGS 994 unsigned int comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; 995 996 if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) 997 return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; 998 #endif 999 return bug_handler(regs, esr) != DBG_HOOK_HANDLED; 1000 } 1001 1002 void __init trap_init(void) 1003 { 1004 register_kernel_break_hook(&bug_break_hook); 1005 register_kernel_break_hook(&fault_break_hook); 1006 #ifdef CONFIG_KASAN_SW_TAGS 1007 register_kernel_break_hook(&kasan_break_hook); 1008 #endif 1009 debug_traps_init(); 1010 } 1011