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/efi.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 #include <linux/ubsan.h> 31 #include <linux/cfi.h> 32 33 #include <asm/atomic.h> 34 #include <asm/bug.h> 35 #include <asm/cpufeature.h> 36 #include <asm/daifflags.h> 37 #include <asm/debug-monitors.h> 38 #include <asm/efi.h> 39 #include <asm/esr.h> 40 #include <asm/exception.h> 41 #include <asm/extable.h> 42 #include <asm/insn.h> 43 #include <asm/kprobes.h> 44 #include <asm/patching.h> 45 #include <asm/traps.h> 46 #include <asm/smp.h> 47 #include <asm/stack_pointer.h> 48 #include <asm/stacktrace.h> 49 #include <asm/system_misc.h> 50 #include <asm/sysreg.h> 51 52 static bool __kprobes __check_eq(unsigned long pstate) 53 { 54 return (pstate & PSR_Z_BIT) != 0; 55 } 56 57 static bool __kprobes __check_ne(unsigned long pstate) 58 { 59 return (pstate & PSR_Z_BIT) == 0; 60 } 61 62 static bool __kprobes __check_cs(unsigned long pstate) 63 { 64 return (pstate & PSR_C_BIT) != 0; 65 } 66 67 static bool __kprobes __check_cc(unsigned long pstate) 68 { 69 return (pstate & PSR_C_BIT) == 0; 70 } 71 72 static bool __kprobes __check_mi(unsigned long pstate) 73 { 74 return (pstate & PSR_N_BIT) != 0; 75 } 76 77 static bool __kprobes __check_pl(unsigned long pstate) 78 { 79 return (pstate & PSR_N_BIT) == 0; 80 } 81 82 static bool __kprobes __check_vs(unsigned long pstate) 83 { 84 return (pstate & PSR_V_BIT) != 0; 85 } 86 87 static bool __kprobes __check_vc(unsigned long pstate) 88 { 89 return (pstate & PSR_V_BIT) == 0; 90 } 91 92 static bool __kprobes __check_hi(unsigned long pstate) 93 { 94 pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ 95 return (pstate & PSR_C_BIT) != 0; 96 } 97 98 static bool __kprobes __check_ls(unsigned long pstate) 99 { 100 pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ 101 return (pstate & PSR_C_BIT) == 0; 102 } 103 104 static bool __kprobes __check_ge(unsigned long pstate) 105 { 106 pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ 107 return (pstate & PSR_N_BIT) == 0; 108 } 109 110 static bool __kprobes __check_lt(unsigned long pstate) 111 { 112 pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ 113 return (pstate & PSR_N_BIT) != 0; 114 } 115 116 static bool __kprobes __check_gt(unsigned long pstate) 117 { 118 /*PSR_N_BIT ^= PSR_V_BIT */ 119 unsigned long temp = pstate ^ (pstate << 3); 120 121 temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ 122 return (temp & PSR_N_BIT) == 0; 123 } 124 125 static bool __kprobes __check_le(unsigned long pstate) 126 { 127 /*PSR_N_BIT ^= PSR_V_BIT */ 128 unsigned long temp = pstate ^ (pstate << 3); 129 130 temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ 131 return (temp & PSR_N_BIT) != 0; 132 } 133 134 static bool __kprobes __check_al(unsigned long pstate) 135 { 136 return true; 137 } 138 139 /* 140 * Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that 141 * it behaves identically to 0b1110 ("al"). 142 */ 143 pstate_check_t * const aarch32_opcode_cond_checks[16] = { 144 __check_eq, __check_ne, __check_cs, __check_cc, 145 __check_mi, __check_pl, __check_vs, __check_vc, 146 __check_hi, __check_ls, __check_ge, __check_lt, 147 __check_gt, __check_le, __check_al, __check_al 148 }; 149 150 int show_unhandled_signals = 0; 151 152 static void dump_kernel_instr(const char *lvl, struct pt_regs *regs) 153 { 154 unsigned long addr = instruction_pointer(regs); 155 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; 156 int i; 157 158 if (user_mode(regs)) 159 return; 160 161 for (i = -4; i < 1; i++) { 162 unsigned int val, bad; 163 164 bad = aarch64_insn_read(&((u32 *)addr)[i], &val); 165 166 if (!bad) 167 p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val); 168 else 169 p += sprintf(p, i == 0 ? "(????????) " : "???????? "); 170 } 171 172 printk("%sCode: %s\n", lvl, str); 173 } 174 175 #ifdef CONFIG_PREEMPT 176 #define S_PREEMPT " PREEMPT" 177 #elif defined(CONFIG_PREEMPT_RT) 178 #define S_PREEMPT " PREEMPT_RT" 179 #else 180 #define S_PREEMPT "" 181 #endif 182 183 #define S_SMP " SMP" 184 185 static int __die(const char *str, long err, struct pt_regs *regs) 186 { 187 static int die_counter; 188 int ret; 189 190 pr_emerg("Internal error: %s: %016lx [#%d]" S_PREEMPT S_SMP "\n", 191 str, err, ++die_counter); 192 193 /* trap and error numbers are mostly meaningless on ARM */ 194 ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV); 195 if (ret == NOTIFY_STOP) 196 return ret; 197 198 print_modules(); 199 show_regs(regs); 200 201 dump_kernel_instr(KERN_EMERG, regs); 202 203 return ret; 204 } 205 206 static DEFINE_RAW_SPINLOCK(die_lock); 207 208 /* 209 * This function is protected against re-entrancy. 210 */ 211 void die(const char *str, struct pt_regs *regs, long err) 212 { 213 int ret; 214 unsigned long flags; 215 216 raw_spin_lock_irqsave(&die_lock, flags); 217 218 oops_enter(); 219 220 console_verbose(); 221 bust_spinlocks(1); 222 ret = __die(str, err, regs); 223 224 if (regs && kexec_should_crash(current)) 225 crash_kexec(regs); 226 227 bust_spinlocks(0); 228 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); 229 oops_exit(); 230 231 if (in_interrupt()) 232 panic("%s: Fatal exception in interrupt", str); 233 if (panic_on_oops) 234 panic("%s: Fatal exception", str); 235 236 raw_spin_unlock_irqrestore(&die_lock, flags); 237 238 if (ret != NOTIFY_STOP) 239 make_task_dead(SIGSEGV); 240 } 241 242 static void arm64_show_signal(int signo, const char *str) 243 { 244 static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, 245 DEFAULT_RATELIMIT_BURST); 246 struct task_struct *tsk = current; 247 unsigned long esr = tsk->thread.fault_code; 248 struct pt_regs *regs = task_pt_regs(tsk); 249 250 /* Leave if the signal won't be shown */ 251 if (!show_unhandled_signals || 252 !unhandled_signal(tsk, signo) || 253 !__ratelimit(&rs)) 254 return; 255 256 pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk)); 257 if (esr) 258 pr_cont("%s, ESR 0x%016lx, ", esr_get_class_string(esr), esr); 259 260 pr_cont("%s", str); 261 print_vma_addr(KERN_CONT " in ", regs->pc); 262 pr_cont("\n"); 263 __show_regs(regs); 264 } 265 266 void arm64_force_sig_fault(int signo, int code, unsigned long far, 267 const char *str) 268 { 269 arm64_show_signal(signo, str); 270 if (signo == SIGKILL) 271 force_sig(SIGKILL); 272 else 273 force_sig_fault(signo, code, (void __user *)far); 274 } 275 276 void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, 277 const char *str) 278 { 279 arm64_show_signal(SIGBUS, str); 280 force_sig_mceerr(code, (void __user *)far, lsb); 281 } 282 283 void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, 284 const char *str) 285 { 286 arm64_show_signal(SIGTRAP, str); 287 force_sig_ptrace_errno_trap(errno, (void __user *)far); 288 } 289 290 void arm64_notify_die(const char *str, struct pt_regs *regs, 291 int signo, int sicode, unsigned long far, 292 unsigned long err) 293 { 294 if (user_mode(regs)) { 295 WARN_ON(regs != current_pt_regs()); 296 current->thread.fault_address = 0; 297 current->thread.fault_code = err; 298 299 arm64_force_sig_fault(signo, sicode, far, str); 300 } else { 301 die(str, regs, err); 302 } 303 } 304 305 #ifdef CONFIG_COMPAT 306 #define PSTATE_IT_1_0_SHIFT 25 307 #define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT) 308 #define PSTATE_IT_7_2_SHIFT 10 309 #define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT) 310 311 static u32 compat_get_it_state(struct pt_regs *regs) 312 { 313 u32 it, pstate = regs->pstate; 314 315 it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT; 316 it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2; 317 318 return it; 319 } 320 321 static void compat_set_it_state(struct pt_regs *regs, u32 it) 322 { 323 u32 pstate_it; 324 325 pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK; 326 pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK; 327 328 regs->pstate &= ~PSR_AA32_IT_MASK; 329 regs->pstate |= pstate_it; 330 } 331 332 static void advance_itstate(struct pt_regs *regs) 333 { 334 u32 it; 335 336 /* ARM mode */ 337 if (!(regs->pstate & PSR_AA32_T_BIT) || 338 !(regs->pstate & PSR_AA32_IT_MASK)) 339 return; 340 341 it = compat_get_it_state(regs); 342 343 /* 344 * If this is the last instruction of the block, wipe the IT 345 * state. Otherwise advance it. 346 */ 347 if (!(it & 7)) 348 it = 0; 349 else 350 it = (it & 0xe0) | ((it << 1) & 0x1f); 351 352 compat_set_it_state(regs, it); 353 } 354 #else 355 static void advance_itstate(struct pt_regs *regs) 356 { 357 } 358 #endif 359 360 void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) 361 { 362 regs->pc += size; 363 364 /* 365 * If we were single stepping, we want to get the step exception after 366 * we return from the trap. 367 */ 368 if (user_mode(regs)) 369 user_fastforward_single_step(current); 370 371 if (compat_user_mode(regs)) 372 advance_itstate(regs); 373 else 374 regs->pstate &= ~PSR_BTYPE_MASK; 375 } 376 377 static int user_insn_read(struct pt_regs *regs, u32 *insnp) 378 { 379 u32 instr; 380 unsigned long pc = instruction_pointer(regs); 381 382 if (compat_thumb_mode(regs)) { 383 /* 16-bit Thumb instruction */ 384 __le16 instr_le; 385 if (get_user(instr_le, (__le16 __user *)pc)) 386 return -EFAULT; 387 instr = le16_to_cpu(instr_le); 388 if (aarch32_insn_is_wide(instr)) { 389 u32 instr2; 390 391 if (get_user(instr_le, (__le16 __user *)(pc + 2))) 392 return -EFAULT; 393 instr2 = le16_to_cpu(instr_le); 394 instr = (instr << 16) | instr2; 395 } 396 } else { 397 /* 32-bit ARM instruction */ 398 __le32 instr_le; 399 if (get_user(instr_le, (__le32 __user *)pc)) 400 return -EFAULT; 401 instr = le32_to_cpu(instr_le); 402 } 403 404 *insnp = instr; 405 return 0; 406 } 407 408 void force_signal_inject(int signal, int code, unsigned long address, unsigned long err) 409 { 410 const char *desc; 411 struct pt_regs *regs = current_pt_regs(); 412 413 if (WARN_ON(!user_mode(regs))) 414 return; 415 416 switch (signal) { 417 case SIGILL: 418 desc = "undefined instruction"; 419 break; 420 case SIGSEGV: 421 desc = "illegal memory access"; 422 break; 423 default: 424 desc = "unknown or unrecoverable error"; 425 break; 426 } 427 428 /* Force signals we don't understand to SIGKILL */ 429 if (WARN_ON(signal != SIGKILL && 430 siginfo_layout(signal, code) != SIL_FAULT)) { 431 signal = SIGKILL; 432 } 433 434 arm64_notify_die(desc, regs, signal, code, address, err); 435 } 436 437 /* 438 * Set up process info to signal segmentation fault - called on access error. 439 */ 440 void arm64_notify_segfault(unsigned long addr) 441 { 442 int code; 443 444 mmap_read_lock(current->mm); 445 if (find_vma(current->mm, untagged_addr(addr)) == NULL) 446 code = SEGV_MAPERR; 447 else 448 code = SEGV_ACCERR; 449 mmap_read_unlock(current->mm); 450 451 force_signal_inject(SIGSEGV, code, addr, 0); 452 } 453 454 void do_el0_undef(struct pt_regs *regs, unsigned long esr) 455 { 456 u32 insn; 457 458 /* check for AArch32 breakpoint instructions */ 459 if (!aarch32_break_handler(regs)) 460 return; 461 462 if (user_insn_read(regs, &insn)) 463 goto out_err; 464 465 if (try_emulate_mrs(regs, insn)) 466 return; 467 468 if (try_emulate_armv8_deprecated(regs, insn)) 469 return; 470 471 out_err: 472 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 473 } 474 475 void do_el1_undef(struct pt_regs *regs, unsigned long esr) 476 { 477 u32 insn; 478 479 if (aarch64_insn_read((void *)regs->pc, &insn)) 480 goto out_err; 481 482 if (try_emulate_el1_ssbs(regs, insn)) 483 return; 484 485 out_err: 486 die("Oops - Undefined instruction", regs, esr); 487 } 488 489 void do_el0_bti(struct pt_regs *regs) 490 { 491 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 492 } 493 494 void do_el1_bti(struct pt_regs *regs, unsigned long esr) 495 { 496 if (efi_runtime_fixup_exception(regs, "BTI violation")) { 497 regs->pstate &= ~PSR_BTYPE_MASK; 498 return; 499 } 500 die("Oops - BTI", regs, esr); 501 } 502 503 void do_el0_fpac(struct pt_regs *regs, unsigned long esr) 504 { 505 force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); 506 } 507 508 void do_el1_fpac(struct pt_regs *regs, unsigned long esr) 509 { 510 /* 511 * Unexpected FPAC exception in the kernel: kill the task before it 512 * does any more harm. 513 */ 514 die("Oops - FPAC", regs, esr); 515 } 516 517 void do_el0_mops(struct pt_regs *regs, unsigned long esr) 518 { 519 bool wrong_option = esr & ESR_ELx_MOPS_ISS_WRONG_OPTION; 520 bool option_a = esr & ESR_ELx_MOPS_ISS_OPTION_A; 521 int dstreg = ESR_ELx_MOPS_ISS_DESTREG(esr); 522 int srcreg = ESR_ELx_MOPS_ISS_SRCREG(esr); 523 int sizereg = ESR_ELx_MOPS_ISS_SIZEREG(esr); 524 unsigned long dst, src, size; 525 526 dst = pt_regs_read_reg(regs, dstreg); 527 src = pt_regs_read_reg(regs, srcreg); 528 size = pt_regs_read_reg(regs, sizereg); 529 530 /* 531 * Put the registers back in the original format suitable for a 532 * prologue instruction, using the generic return routine from the 533 * Arm ARM (DDI 0487I.a) rules CNTMJ and MWFQH. 534 */ 535 if (esr & ESR_ELx_MOPS_ISS_MEM_INST) { 536 /* SET* instruction */ 537 if (option_a ^ wrong_option) { 538 /* Format is from Option A; forward set */ 539 pt_regs_write_reg(regs, dstreg, dst + size); 540 pt_regs_write_reg(regs, sizereg, -size); 541 } 542 } else { 543 /* CPY* instruction */ 544 if (!(option_a ^ wrong_option)) { 545 /* Format is from Option B */ 546 if (regs->pstate & PSR_N_BIT) { 547 /* Backward copy */ 548 pt_regs_write_reg(regs, dstreg, dst - size); 549 pt_regs_write_reg(regs, srcreg, src - size); 550 } 551 } else { 552 /* Format is from Option A */ 553 if (size & BIT(63)) { 554 /* Forward copy */ 555 pt_regs_write_reg(regs, dstreg, dst + size); 556 pt_regs_write_reg(regs, srcreg, src + size); 557 pt_regs_write_reg(regs, sizereg, -size); 558 } 559 } 560 } 561 562 if (esr & ESR_ELx_MOPS_ISS_FROM_EPILOGUE) 563 regs->pc -= 8; 564 else 565 regs->pc -= 4; 566 } 567 568 #define __user_cache_maint(insn, address, res) \ 569 if (address >= TASK_SIZE_MAX) { \ 570 res = -EFAULT; \ 571 } else { \ 572 uaccess_ttbr0_enable(); \ 573 asm volatile ( \ 574 "1: " insn ", %1\n" \ 575 " mov %w0, #0\n" \ 576 "2:\n" \ 577 _ASM_EXTABLE_UACCESS_ERR(1b, 2b, %w0) \ 578 : "=r" (res) \ 579 : "r" (address)); \ 580 uaccess_ttbr0_disable(); \ 581 } 582 583 static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs) 584 { 585 unsigned long tagged_address, address; 586 int rt = ESR_ELx_SYS64_ISS_RT(esr); 587 int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; 588 int ret = 0; 589 590 tagged_address = pt_regs_read_reg(regs, rt); 591 address = untagged_addr(tagged_address); 592 593 switch (crm) { 594 case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ 595 __user_cache_maint("dc civac", address, ret); 596 break; 597 case ESR_ELx_SYS64_ISS_CRM_DC_CVAC: /* DC CVAC, gets promoted */ 598 __user_cache_maint("dc civac", address, ret); 599 break; 600 case ESR_ELx_SYS64_ISS_CRM_DC_CVADP: /* DC CVADP */ 601 __user_cache_maint("sys 3, c7, c13, 1", address, ret); 602 break; 603 case ESR_ELx_SYS64_ISS_CRM_DC_CVAP: /* DC CVAP */ 604 __user_cache_maint("sys 3, c7, c12, 1", address, ret); 605 break; 606 case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC: /* DC CIVAC */ 607 __user_cache_maint("dc civac", address, ret); 608 break; 609 case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */ 610 __user_cache_maint("ic ivau", address, ret); 611 break; 612 default: 613 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 614 return; 615 } 616 617 if (ret) 618 arm64_notify_segfault(tagged_address); 619 else 620 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 621 } 622 623 static void ctr_read_handler(unsigned long esr, struct pt_regs *regs) 624 { 625 int rt = ESR_ELx_SYS64_ISS_RT(esr); 626 unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); 627 628 if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { 629 /* Hide DIC so that we can trap the unnecessary maintenance...*/ 630 val &= ~BIT(CTR_EL0_DIC_SHIFT); 631 632 /* ... and fake IminLine to reduce the number of traps. */ 633 val &= ~CTR_EL0_IminLine_MASK; 634 val |= (PAGE_SHIFT - 2) & CTR_EL0_IminLine_MASK; 635 } 636 637 pt_regs_write_reg(regs, rt, val); 638 639 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 640 } 641 642 static void cntvct_read_handler(unsigned long esr, struct pt_regs *regs) 643 { 644 int rt = ESR_ELx_SYS64_ISS_RT(esr); 645 646 pt_regs_write_reg(regs, rt, arch_timer_read_counter()); 647 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 648 } 649 650 static void cntfrq_read_handler(unsigned long esr, struct pt_regs *regs) 651 { 652 int rt = ESR_ELx_SYS64_ISS_RT(esr); 653 654 pt_regs_write_reg(regs, rt, arch_timer_get_rate()); 655 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 656 } 657 658 static void mrs_handler(unsigned long esr, struct pt_regs *regs) 659 { 660 u32 sysreg, rt; 661 662 rt = ESR_ELx_SYS64_ISS_RT(esr); 663 sysreg = esr_sys64_to_sysreg(esr); 664 665 if (do_emulate_mrs(regs, sysreg, rt) != 0) 666 force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); 667 } 668 669 static void wfi_handler(unsigned long esr, struct pt_regs *regs) 670 { 671 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 672 } 673 674 struct sys64_hook { 675 unsigned long esr_mask; 676 unsigned long esr_val; 677 void (*handler)(unsigned long esr, struct pt_regs *regs); 678 }; 679 680 static const struct sys64_hook sys64_hooks[] = { 681 { 682 .esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK, 683 .esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL, 684 .handler = user_cache_maint_handler, 685 }, 686 { 687 /* Trap read access to CTR_EL0 */ 688 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 689 .esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ, 690 .handler = ctr_read_handler, 691 }, 692 { 693 /* Trap read access to CNTVCT_EL0 */ 694 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 695 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, 696 .handler = cntvct_read_handler, 697 }, 698 { 699 /* Trap read access to CNTVCTSS_EL0 */ 700 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 701 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCTSS, 702 .handler = cntvct_read_handler, 703 }, 704 { 705 /* Trap read access to CNTFRQ_EL0 */ 706 .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, 707 .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ, 708 .handler = cntfrq_read_handler, 709 }, 710 { 711 /* Trap read access to CPUID registers */ 712 .esr_mask = ESR_ELx_SYS64_ISS_SYS_MRS_OP_MASK, 713 .esr_val = ESR_ELx_SYS64_ISS_SYS_MRS_OP_VAL, 714 .handler = mrs_handler, 715 }, 716 { 717 /* Trap WFI instructions executed in userspace */ 718 .esr_mask = ESR_ELx_WFx_MASK, 719 .esr_val = ESR_ELx_WFx_WFI_VAL, 720 .handler = wfi_handler, 721 }, 722 {}, 723 }; 724 725 #ifdef CONFIG_COMPAT 726 static bool cp15_cond_valid(unsigned long esr, struct pt_regs *regs) 727 { 728 int cond; 729 730 /* Only a T32 instruction can trap without CV being set */ 731 if (!(esr & ESR_ELx_CV)) { 732 u32 it; 733 734 it = compat_get_it_state(regs); 735 if (!it) 736 return true; 737 738 cond = it >> 4; 739 } else { 740 cond = (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT; 741 } 742 743 return aarch32_opcode_cond_checks[cond](regs->pstate); 744 } 745 746 static void compat_cntfrq_read_handler(unsigned long esr, struct pt_regs *regs) 747 { 748 int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT; 749 750 pt_regs_write_reg(regs, reg, arch_timer_get_rate()); 751 arm64_skip_faulting_instruction(regs, 4); 752 } 753 754 static const struct sys64_hook cp15_32_hooks[] = { 755 { 756 .esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK, 757 .esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ, 758 .handler = compat_cntfrq_read_handler, 759 }, 760 {}, 761 }; 762 763 static void compat_cntvct_read_handler(unsigned long esr, struct pt_regs *regs) 764 { 765 int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT; 766 int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT; 767 u64 val = arch_timer_read_counter(); 768 769 pt_regs_write_reg(regs, rt, lower_32_bits(val)); 770 pt_regs_write_reg(regs, rt2, upper_32_bits(val)); 771 arm64_skip_faulting_instruction(regs, 4); 772 } 773 774 static const struct sys64_hook cp15_64_hooks[] = { 775 { 776 .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, 777 .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT, 778 .handler = compat_cntvct_read_handler, 779 }, 780 { 781 .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, 782 .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCTSS, 783 .handler = compat_cntvct_read_handler, 784 }, 785 {}, 786 }; 787 788 void do_el0_cp15(unsigned long esr, struct pt_regs *regs) 789 { 790 const struct sys64_hook *hook, *hook_base; 791 792 if (!cp15_cond_valid(esr, regs)) { 793 /* 794 * There is no T16 variant of a CP access, so we 795 * always advance PC by 4 bytes. 796 */ 797 arm64_skip_faulting_instruction(regs, 4); 798 return; 799 } 800 801 switch (ESR_ELx_EC(esr)) { 802 case ESR_ELx_EC_CP15_32: 803 hook_base = cp15_32_hooks; 804 break; 805 case ESR_ELx_EC_CP15_64: 806 hook_base = cp15_64_hooks; 807 break; 808 default: 809 do_el0_undef(regs, esr); 810 return; 811 } 812 813 for (hook = hook_base; hook->handler; hook++) 814 if ((hook->esr_mask & esr) == hook->esr_val) { 815 hook->handler(esr, regs); 816 return; 817 } 818 819 /* 820 * New cp15 instructions may previously have been undefined at 821 * EL0. Fall back to our usual undefined instruction handler 822 * so that we handle these consistently. 823 */ 824 do_el0_undef(regs, esr); 825 } 826 #endif 827 828 void do_el0_sys(unsigned long esr, struct pt_regs *regs) 829 { 830 const struct sys64_hook *hook; 831 832 for (hook = sys64_hooks; hook->handler; hook++) 833 if ((hook->esr_mask & esr) == hook->esr_val) { 834 hook->handler(esr, regs); 835 return; 836 } 837 838 /* 839 * New SYS instructions may previously have been undefined at EL0. Fall 840 * back to our usual undefined instruction handler so that we handle 841 * these consistently. 842 */ 843 do_el0_undef(regs, esr); 844 } 845 846 static const char *esr_class_str[] = { 847 [0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC", 848 [ESR_ELx_EC_UNKNOWN] = "Unknown/Uncategorized", 849 [ESR_ELx_EC_WFx] = "WFI/WFE", 850 [ESR_ELx_EC_CP15_32] = "CP15 MCR/MRC", 851 [ESR_ELx_EC_CP15_64] = "CP15 MCRR/MRRC", 852 [ESR_ELx_EC_CP14_MR] = "CP14 MCR/MRC", 853 [ESR_ELx_EC_CP14_LS] = "CP14 LDC/STC", 854 [ESR_ELx_EC_FP_ASIMD] = "ASIMD", 855 [ESR_ELx_EC_CP10_ID] = "CP10 MRC/VMRS", 856 [ESR_ELx_EC_PAC] = "PAC", 857 [ESR_ELx_EC_CP14_64] = "CP14 MCRR/MRRC", 858 [ESR_ELx_EC_BTI] = "BTI", 859 [ESR_ELx_EC_ILL] = "PSTATE.IL", 860 [ESR_ELx_EC_SVC32] = "SVC (AArch32)", 861 [ESR_ELx_EC_HVC32] = "HVC (AArch32)", 862 [ESR_ELx_EC_SMC32] = "SMC (AArch32)", 863 [ESR_ELx_EC_SVC64] = "SVC (AArch64)", 864 [ESR_ELx_EC_HVC64] = "HVC (AArch64)", 865 [ESR_ELx_EC_SMC64] = "SMC (AArch64)", 866 [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)", 867 [ESR_ELx_EC_SVE] = "SVE", 868 [ESR_ELx_EC_ERET] = "ERET/ERETAA/ERETAB", 869 [ESR_ELx_EC_FPAC] = "FPAC", 870 [ESR_ELx_EC_SME] = "SME", 871 [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF", 872 [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)", 873 [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)", 874 [ESR_ELx_EC_PC_ALIGN] = "PC Alignment", 875 [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", 876 [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", 877 [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", 878 [ESR_ELx_EC_MOPS] = "MOPS", 879 [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", 880 [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", 881 [ESR_ELx_EC_SERROR] = "SError", 882 [ESR_ELx_EC_BREAKPT_LOW] = "Breakpoint (lower EL)", 883 [ESR_ELx_EC_BREAKPT_CUR] = "Breakpoint (current EL)", 884 [ESR_ELx_EC_SOFTSTP_LOW] = "Software Step (lower EL)", 885 [ESR_ELx_EC_SOFTSTP_CUR] = "Software Step (current EL)", 886 [ESR_ELx_EC_WATCHPT_LOW] = "Watchpoint (lower EL)", 887 [ESR_ELx_EC_WATCHPT_CUR] = "Watchpoint (current EL)", 888 [ESR_ELx_EC_BKPT32] = "BKPT (AArch32)", 889 [ESR_ELx_EC_VECTOR32] = "Vector catch (AArch32)", 890 [ESR_ELx_EC_BRK64] = "BRK (AArch64)", 891 }; 892 893 const char *esr_get_class_string(unsigned long esr) 894 { 895 return esr_class_str[ESR_ELx_EC(esr)]; 896 } 897 898 /* 899 * bad_el0_sync handles unexpected, but potentially recoverable synchronous 900 * exceptions taken from EL0. 901 */ 902 void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr) 903 { 904 unsigned long pc = instruction_pointer(regs); 905 906 current->thread.fault_address = 0; 907 current->thread.fault_code = esr; 908 909 arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, 910 "Bad EL0 synchronous exception"); 911 } 912 913 #ifdef CONFIG_VMAP_STACK 914 915 DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack) 916 __aligned(16); 917 918 void __noreturn panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far) 919 { 920 unsigned long tsk_stk = (unsigned long)current->stack; 921 unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr); 922 unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); 923 924 console_verbose(); 925 pr_emerg("Insufficient stack space to handle exception!"); 926 927 pr_emerg("ESR: 0x%016lx -- %s\n", esr, esr_get_class_string(esr)); 928 pr_emerg("FAR: 0x%016lx\n", far); 929 930 pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", 931 tsk_stk, tsk_stk + THREAD_SIZE); 932 pr_emerg("IRQ stack: [0x%016lx..0x%016lx]\n", 933 irq_stk, irq_stk + IRQ_STACK_SIZE); 934 pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", 935 ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); 936 937 __show_regs(regs); 938 939 /* 940 * We use nmi_panic to limit the potential for recusive overflows, and 941 * to get a better stack trace. 942 */ 943 nmi_panic(NULL, "kernel stack overflow"); 944 cpu_park_loop(); 945 } 946 #endif 947 948 void __noreturn arm64_serror_panic(struct pt_regs *regs, unsigned long esr) 949 { 950 console_verbose(); 951 952 pr_crit("SError Interrupt on CPU%d, code 0x%016lx -- %s\n", 953 smp_processor_id(), esr, esr_get_class_string(esr)); 954 if (regs) 955 __show_regs(regs); 956 957 nmi_panic(regs, "Asynchronous SError Interrupt"); 958 959 cpu_park_loop(); 960 } 961 962 bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned long esr) 963 { 964 unsigned long aet = arm64_ras_serror_get_severity(esr); 965 966 switch (aet) { 967 case ESR_ELx_AET_CE: /* corrected error */ 968 case ESR_ELx_AET_UEO: /* restartable, not yet consumed */ 969 /* 970 * The CPU can make progress. We may take UEO again as 971 * a more severe error. 972 */ 973 return false; 974 975 case ESR_ELx_AET_UEU: /* Uncorrected Unrecoverable */ 976 case ESR_ELx_AET_UER: /* Uncorrected Recoverable */ 977 /* 978 * The CPU can't make progress. The exception may have 979 * been imprecise. 980 * 981 * Neoverse-N1 #1349291 means a non-KVM SError reported as 982 * Unrecoverable should be treated as Uncontainable. We 983 * call arm64_serror_panic() in both cases. 984 */ 985 return true; 986 987 case ESR_ELx_AET_UC: /* Uncontainable or Uncategorized error */ 988 default: 989 /* Error has been silently propagated */ 990 arm64_serror_panic(regs, esr); 991 } 992 } 993 994 void do_serror(struct pt_regs *regs, unsigned long esr) 995 { 996 /* non-RAS errors are not containable */ 997 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr)) 998 arm64_serror_panic(regs, esr); 999 } 1000 1001 /* GENERIC_BUG traps */ 1002 1003 int is_valid_bugaddr(unsigned long addr) 1004 { 1005 /* 1006 * bug_handler() only called for BRK #BUG_BRK_IMM. 1007 * So the answer is trivial -- any spurious instances with no 1008 * bug table entry will be rejected by report_bug() and passed 1009 * back to the debug-monitors code and handled as a fatal 1010 * unexpected debug exception. 1011 */ 1012 return 1; 1013 } 1014 1015 static int bug_handler(struct pt_regs *regs, unsigned long esr) 1016 { 1017 switch (report_bug(regs->pc, regs)) { 1018 case BUG_TRAP_TYPE_BUG: 1019 die("Oops - BUG", regs, esr); 1020 break; 1021 1022 case BUG_TRAP_TYPE_WARN: 1023 break; 1024 1025 default: 1026 /* unknown/unrecognised bug trap type */ 1027 return DBG_HOOK_ERROR; 1028 } 1029 1030 /* If thread survives, skip over the BUG instruction and continue: */ 1031 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 1032 return DBG_HOOK_HANDLED; 1033 } 1034 1035 static struct break_hook bug_break_hook = { 1036 .fn = bug_handler, 1037 .imm = BUG_BRK_IMM, 1038 }; 1039 1040 #ifdef CONFIG_CFI_CLANG 1041 static int cfi_handler(struct pt_regs *regs, unsigned long esr) 1042 { 1043 unsigned long target; 1044 u32 type; 1045 1046 target = pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TARGET, esr)); 1047 type = (u32)pt_regs_read_reg(regs, FIELD_GET(CFI_BRK_IMM_TYPE, esr)); 1048 1049 switch (report_cfi_failure(regs, regs->pc, &target, type)) { 1050 case BUG_TRAP_TYPE_BUG: 1051 die("Oops - CFI", regs, esr); 1052 break; 1053 1054 case BUG_TRAP_TYPE_WARN: 1055 break; 1056 1057 default: 1058 return DBG_HOOK_ERROR; 1059 } 1060 1061 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 1062 return DBG_HOOK_HANDLED; 1063 } 1064 1065 static struct break_hook cfi_break_hook = { 1066 .fn = cfi_handler, 1067 .imm = CFI_BRK_IMM_BASE, 1068 .mask = CFI_BRK_IMM_MASK, 1069 }; 1070 #endif /* CONFIG_CFI_CLANG */ 1071 1072 static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr) 1073 { 1074 pr_err("%s generated an invalid instruction at %pS!\n", 1075 "Kernel text patching", 1076 (void *)instruction_pointer(regs)); 1077 1078 /* We cannot handle this */ 1079 return DBG_HOOK_ERROR; 1080 } 1081 1082 static struct break_hook fault_break_hook = { 1083 .fn = reserved_fault_handler, 1084 .imm = FAULT_BRK_IMM, 1085 }; 1086 1087 #ifdef CONFIG_KASAN_SW_TAGS 1088 1089 #define KASAN_ESR_RECOVER 0x20 1090 #define KASAN_ESR_WRITE 0x10 1091 #define KASAN_ESR_SIZE_MASK 0x0f 1092 #define KASAN_ESR_SIZE(esr) (1 << ((esr) & KASAN_ESR_SIZE_MASK)) 1093 1094 static int kasan_handler(struct pt_regs *regs, unsigned long esr) 1095 { 1096 bool recover = esr & KASAN_ESR_RECOVER; 1097 bool write = esr & KASAN_ESR_WRITE; 1098 size_t size = KASAN_ESR_SIZE(esr); 1099 u64 addr = regs->regs[0]; 1100 u64 pc = regs->pc; 1101 1102 kasan_report(addr, size, write, pc); 1103 1104 /* 1105 * The instrumentation allows to control whether we can proceed after 1106 * a crash was detected. This is done by passing the -recover flag to 1107 * the compiler. Disabling recovery allows to generate more compact 1108 * code. 1109 * 1110 * Unfortunately disabling recovery doesn't work for the kernel right 1111 * now. KASAN reporting is disabled in some contexts (for example when 1112 * the allocator accesses slab object metadata; this is controlled by 1113 * current->kasan_depth). All these accesses are detected by the tool, 1114 * even though the reports for them are not printed. 1115 * 1116 * This is something that might be fixed at some point in the future. 1117 */ 1118 if (!recover) 1119 die("Oops - KASAN", regs, esr); 1120 1121 /* If thread survives, skip over the brk instruction and continue: */ 1122 arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); 1123 return DBG_HOOK_HANDLED; 1124 } 1125 1126 static struct break_hook kasan_break_hook = { 1127 .fn = kasan_handler, 1128 .imm = KASAN_BRK_IMM, 1129 .mask = KASAN_BRK_MASK, 1130 }; 1131 #endif 1132 1133 #ifdef CONFIG_UBSAN_TRAP 1134 static int ubsan_handler(struct pt_regs *regs, unsigned long esr) 1135 { 1136 die(report_ubsan_failure(regs, esr & UBSAN_BRK_MASK), regs, esr); 1137 return DBG_HOOK_HANDLED; 1138 } 1139 1140 static struct break_hook ubsan_break_hook = { 1141 .fn = ubsan_handler, 1142 .imm = UBSAN_BRK_IMM, 1143 .mask = UBSAN_BRK_MASK, 1144 }; 1145 #endif 1146 1147 #define esr_comment(esr) ((esr) & ESR_ELx_BRK64_ISS_COMMENT_MASK) 1148 1149 /* 1150 * Initial handler for AArch64 BRK exceptions 1151 * This handler only used until debug_traps_init(). 1152 */ 1153 int __init early_brk64(unsigned long addr, unsigned long esr, 1154 struct pt_regs *regs) 1155 { 1156 #ifdef CONFIG_CFI_CLANG 1157 if ((esr_comment(esr) & ~CFI_BRK_IMM_MASK) == CFI_BRK_IMM_BASE) 1158 return cfi_handler(regs, esr) != DBG_HOOK_HANDLED; 1159 #endif 1160 #ifdef CONFIG_KASAN_SW_TAGS 1161 if ((esr_comment(esr) & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) 1162 return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; 1163 #endif 1164 #ifdef CONFIG_UBSAN_TRAP 1165 if ((esr_comment(esr) & ~UBSAN_BRK_MASK) == UBSAN_BRK_IMM) 1166 return ubsan_handler(regs, esr) != DBG_HOOK_HANDLED; 1167 #endif 1168 return bug_handler(regs, esr) != DBG_HOOK_HANDLED; 1169 } 1170 1171 void __init trap_init(void) 1172 { 1173 register_kernel_break_hook(&bug_break_hook); 1174 #ifdef CONFIG_CFI_CLANG 1175 register_kernel_break_hook(&cfi_break_hook); 1176 #endif 1177 register_kernel_break_hook(&fault_break_hook); 1178 #ifdef CONFIG_KASAN_SW_TAGS 1179 register_kernel_break_hook(&kasan_break_hook); 1180 #endif 1181 #ifdef CONFIG_UBSAN_TRAP 1182 register_kernel_break_hook(&ubsan_break_hook); 1183 #endif 1184 debug_traps_init(); 1185 } 1186