// SPDX-License-Identifier: GPL-2.0-only /* * Based on arch/arm/kernel/traps.c * * Copyright (C) 1995-2009 Russell King * Copyright (C) 2012 ARM Ltd. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static bool __kprobes __check_eq(unsigned long pstate) { return (pstate & PSR_Z_BIT) != 0; } static bool __kprobes __check_ne(unsigned long pstate) { return (pstate & PSR_Z_BIT) == 0; } static bool __kprobes __check_cs(unsigned long pstate) { return (pstate & PSR_C_BIT) != 0; } static bool __kprobes __check_cc(unsigned long pstate) { return (pstate & PSR_C_BIT) == 0; } static bool __kprobes __check_mi(unsigned long pstate) { return (pstate & PSR_N_BIT) != 0; } static bool __kprobes __check_pl(unsigned long pstate) { return (pstate & PSR_N_BIT) == 0; } static bool __kprobes __check_vs(unsigned long pstate) { return (pstate & PSR_V_BIT) != 0; } static bool __kprobes __check_vc(unsigned long pstate) { return (pstate & PSR_V_BIT) == 0; } static bool __kprobes __check_hi(unsigned long pstate) { pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ return (pstate & PSR_C_BIT) != 0; } static bool __kprobes __check_ls(unsigned long pstate) { pstate &= ~(pstate >> 1); /* PSR_C_BIT &= ~PSR_Z_BIT */ return (pstate & PSR_C_BIT) == 0; } static bool __kprobes __check_ge(unsigned long pstate) { pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ return (pstate & PSR_N_BIT) == 0; } static bool __kprobes __check_lt(unsigned long pstate) { pstate ^= (pstate << 3); /* PSR_N_BIT ^= PSR_V_BIT */ return (pstate & PSR_N_BIT) != 0; } static bool __kprobes __check_gt(unsigned long pstate) { /*PSR_N_BIT ^= PSR_V_BIT */ unsigned long temp = pstate ^ (pstate << 3); temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ return (temp & PSR_N_BIT) == 0; } static bool __kprobes __check_le(unsigned long pstate) { /*PSR_N_BIT ^= PSR_V_BIT */ unsigned long temp = pstate ^ (pstate << 3); temp |= (pstate << 1); /*PSR_N_BIT |= PSR_Z_BIT */ return (temp & PSR_N_BIT) != 0; } static bool __kprobes __check_al(unsigned long pstate) { return true; } /* * Note that the ARMv8 ARM calls condition code 0b1111 "nv", but states that * it behaves identically to 0b1110 ("al"). */ pstate_check_t * const aarch32_opcode_cond_checks[16] = { __check_eq, __check_ne, __check_cs, __check_cc, __check_mi, __check_pl, __check_vs, __check_vc, __check_hi, __check_ls, __check_ge, __check_lt, __check_gt, __check_le, __check_al, __check_al }; int show_unhandled_signals = 0; static void dump_kernel_instr(const char *lvl, struct pt_regs *regs) { unsigned long addr = instruction_pointer(regs); char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str; int i; if (user_mode(regs)) return; for (i = -4; i < 1; i++) { unsigned int val, bad; bad = aarch64_insn_read(&((u32 *)addr)[i], &val); if (!bad) p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val); else { p += sprintf(p, "bad PC value"); break; } } printk("%sCode: %s\n", lvl, str); } #ifdef CONFIG_PREEMPT #define S_PREEMPT " PREEMPT" #elif defined(CONFIG_PREEMPT_RT) #define S_PREEMPT " PREEMPT_RT" #else #define S_PREEMPT "" #endif #define S_SMP " SMP" static int __die(const char *str, long err, struct pt_regs *regs) { static int die_counter; int ret; pr_emerg("Internal error: %s: %016lx [#%d]" S_PREEMPT S_SMP "\n", str, err, ++die_counter); /* trap and error numbers are mostly meaningless on ARM */ ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV); if (ret == NOTIFY_STOP) return ret; print_modules(); show_regs(regs); dump_kernel_instr(KERN_EMERG, regs); return ret; } static DEFINE_RAW_SPINLOCK(die_lock); /* * This function is protected against re-entrancy. */ void die(const char *str, struct pt_regs *regs, long err) { int ret; unsigned long flags; raw_spin_lock_irqsave(&die_lock, flags); oops_enter(); console_verbose(); bust_spinlocks(1); ret = __die(str, err, regs); if (regs && kexec_should_crash(current)) crash_kexec(regs); bust_spinlocks(0); add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE); oops_exit(); if (in_interrupt()) panic("%s: Fatal exception in interrupt", str); if (panic_on_oops) panic("%s: Fatal exception", str); raw_spin_unlock_irqrestore(&die_lock, flags); if (ret != NOTIFY_STOP) make_task_dead(SIGSEGV); } static void arm64_show_signal(int signo, const char *str) { static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); struct task_struct *tsk = current; unsigned long esr = tsk->thread.fault_code; struct pt_regs *regs = task_pt_regs(tsk); /* Leave if the signal won't be shown */ if (!show_unhandled_signals || !unhandled_signal(tsk, signo) || !__ratelimit(&rs)) return; pr_info("%s[%d]: unhandled exception: ", tsk->comm, task_pid_nr(tsk)); if (esr) pr_cont("%s, ESR 0x%016lx, ", esr_get_class_string(esr), esr); pr_cont("%s", str); print_vma_addr(KERN_CONT " in ", regs->pc); pr_cont("\n"); __show_regs(regs); } void arm64_force_sig_fault(int signo, int code, unsigned long far, const char *str) { arm64_show_signal(signo, str); if (signo == SIGKILL) force_sig(SIGKILL); else force_sig_fault(signo, code, (void __user *)far); } void arm64_force_sig_mceerr(int code, unsigned long far, short lsb, const char *str) { arm64_show_signal(SIGBUS, str); force_sig_mceerr(code, (void __user *)far, lsb); } void arm64_force_sig_ptrace_errno_trap(int errno, unsigned long far, const char *str) { arm64_show_signal(SIGTRAP, str); force_sig_ptrace_errno_trap(errno, (void __user *)far); } void arm64_notify_die(const char *str, struct pt_regs *regs, int signo, int sicode, unsigned long far, unsigned long err) { if (user_mode(regs)) { WARN_ON(regs != current_pt_regs()); current->thread.fault_address = 0; current->thread.fault_code = err; arm64_force_sig_fault(signo, sicode, far, str); } else { die(str, regs, err); } } #ifdef CONFIG_COMPAT #define PSTATE_IT_1_0_SHIFT 25 #define PSTATE_IT_1_0_MASK (0x3 << PSTATE_IT_1_0_SHIFT) #define PSTATE_IT_7_2_SHIFT 10 #define PSTATE_IT_7_2_MASK (0x3f << PSTATE_IT_7_2_SHIFT) static u32 compat_get_it_state(struct pt_regs *regs) { u32 it, pstate = regs->pstate; it = (pstate & PSTATE_IT_1_0_MASK) >> PSTATE_IT_1_0_SHIFT; it |= ((pstate & PSTATE_IT_7_2_MASK) >> PSTATE_IT_7_2_SHIFT) << 2; return it; } static void compat_set_it_state(struct pt_regs *regs, u32 it) { u32 pstate_it; pstate_it = (it << PSTATE_IT_1_0_SHIFT) & PSTATE_IT_1_0_MASK; pstate_it |= ((it >> 2) << PSTATE_IT_7_2_SHIFT) & PSTATE_IT_7_2_MASK; regs->pstate &= ~PSR_AA32_IT_MASK; regs->pstate |= pstate_it; } static void advance_itstate(struct pt_regs *regs) { u32 it; /* ARM mode */ if (!(regs->pstate & PSR_AA32_T_BIT) || !(regs->pstate & PSR_AA32_IT_MASK)) return; it = compat_get_it_state(regs); /* * If this is the last instruction of the block, wipe the IT * state. Otherwise advance it. */ if (!(it & 7)) it = 0; else it = (it & 0xe0) | ((it << 1) & 0x1f); compat_set_it_state(regs, it); } #else static void advance_itstate(struct pt_regs *regs) { } #endif void arm64_skip_faulting_instruction(struct pt_regs *regs, unsigned long size) { regs->pc += size; /* * If we were single stepping, we want to get the step exception after * we return from the trap. */ if (user_mode(regs)) user_fastforward_single_step(current); if (compat_user_mode(regs)) advance_itstate(regs); else regs->pstate &= ~PSR_BTYPE_MASK; } static int user_insn_read(struct pt_regs *regs, u32 *insnp) { u32 instr; void __user *pc = (void __user *)instruction_pointer(regs); if (compat_thumb_mode(regs)) { /* 16-bit Thumb instruction */ __le16 instr_le; if (get_user(instr_le, (__le16 __user *)pc)) return -EFAULT; instr = le16_to_cpu(instr_le); if (aarch32_insn_is_wide(instr)) { u32 instr2; if (get_user(instr_le, (__le16 __user *)(pc + 2))) return -EFAULT; instr2 = le16_to_cpu(instr_le); instr = (instr << 16) | instr2; } } else { /* 32-bit ARM instruction */ __le32 instr_le; if (get_user(instr_le, (__le32 __user *)pc)) return -EFAULT; instr = le32_to_cpu(instr_le); } *insnp = instr; return 0; } void force_signal_inject(int signal, int code, unsigned long address, unsigned long err) { const char *desc; struct pt_regs *regs = current_pt_regs(); if (WARN_ON(!user_mode(regs))) return; switch (signal) { case SIGILL: desc = "undefined instruction"; break; case SIGSEGV: desc = "illegal memory access"; break; default: desc = "unknown or unrecoverable error"; break; } /* Force signals we don't understand to SIGKILL */ if (WARN_ON(signal != SIGKILL && siginfo_layout(signal, code) != SIL_FAULT)) { signal = SIGKILL; } arm64_notify_die(desc, regs, signal, code, address, err); } /* * Set up process info to signal segmentation fault - called on access error. */ void arm64_notify_segfault(unsigned long addr) { int code; mmap_read_lock(current->mm); if (find_vma(current->mm, untagged_addr(addr)) == NULL) code = SEGV_MAPERR; else code = SEGV_ACCERR; mmap_read_unlock(current->mm); force_signal_inject(SIGSEGV, code, addr, 0); } void do_el0_undef(struct pt_regs *regs, unsigned long esr) { u32 insn; /* check for AArch32 breakpoint instructions */ if (!aarch32_break_handler(regs)) return; if (user_insn_read(regs, &insn)) goto out_err; if (try_emulate_mrs(regs, insn)) return; if (try_emulate_armv8_deprecated(regs, insn)) return; out_err: force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); } void do_el1_undef(struct pt_regs *regs, unsigned long esr) { u32 insn; if (aarch64_insn_read((void *)regs->pc, &insn)) goto out_err; if (try_emulate_el1_ssbs(regs, insn)) return; out_err: die("Oops - Undefined instruction", regs, esr); } void do_el0_bti(struct pt_regs *regs) { force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); } void do_el1_bti(struct pt_regs *regs, unsigned long esr) { die("Oops - BTI", regs, esr); } void do_el0_fpac(struct pt_regs *regs, unsigned long esr) { force_signal_inject(SIGILL, ILL_ILLOPN, regs->pc, esr); } void do_el1_fpac(struct pt_regs *regs, unsigned long esr) { /* * Unexpected FPAC exception in the kernel: kill the task before it * does any more harm. */ die("Oops - FPAC", regs, esr); } #define __user_cache_maint(insn, address, res) \ if (address >= user_addr_max()) { \ res = -EFAULT; \ } else { \ uaccess_ttbr0_enable(); \ asm volatile ( \ "1: " insn ", %1\n" \ " mov %w0, #0\n" \ "2:\n" \ " .pushsection .fixup,\"ax\"\n" \ " .align 2\n" \ "3: mov %w0, %w2\n" \ " b 2b\n" \ " .popsection\n" \ _ASM_EXTABLE(1b, 3b) \ : "=r" (res) \ : "r" (address), "i" (-EFAULT)); \ uaccess_ttbr0_disable(); \ } static void user_cache_maint_handler(unsigned long esr, struct pt_regs *regs) { unsigned long tagged_address, address; int rt = ESR_ELx_SYS64_ISS_RT(esr); int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; int ret = 0; tagged_address = pt_regs_read_reg(regs, rt); address = untagged_addr(tagged_address); switch (crm) { case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ __user_cache_maint("dc civac", address, ret); break; case ESR_ELx_SYS64_ISS_CRM_DC_CVAC: /* DC CVAC, gets promoted */ __user_cache_maint("dc civac", address, ret); break; case ESR_ELx_SYS64_ISS_CRM_DC_CVADP: /* DC CVADP */ __user_cache_maint("sys 3, c7, c13, 1", address, ret); break; case ESR_ELx_SYS64_ISS_CRM_DC_CVAP: /* DC CVAP */ __user_cache_maint("sys 3, c7, c12, 1", address, ret); break; case ESR_ELx_SYS64_ISS_CRM_DC_CIVAC: /* DC CIVAC */ __user_cache_maint("dc civac", address, ret); break; case ESR_ELx_SYS64_ISS_CRM_IC_IVAU: /* IC IVAU */ __user_cache_maint("ic ivau", address, ret); break; default: force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); return; } if (ret) arm64_notify_segfault(tagged_address); else arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); } static void ctr_read_handler(unsigned long esr, struct pt_regs *regs) { int rt = ESR_ELx_SYS64_ISS_RT(esr); unsigned long val = arm64_ftr_reg_user_value(&arm64_ftr_reg_ctrel0); if (cpus_have_const_cap(ARM64_WORKAROUND_1542419)) { /* Hide DIC so that we can trap the unnecessary maintenance...*/ val &= ~BIT(CTR_DIC_SHIFT); /* ... and fake IminLine to reduce the number of traps. */ val &= ~CTR_IMINLINE_MASK; val |= (PAGE_SHIFT - 2) & CTR_IMINLINE_MASK; } pt_regs_write_reg(regs, rt, val); arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); } static void cntvct_read_handler(unsigned long esr, struct pt_regs *regs) { int rt = ESR_ELx_SYS64_ISS_RT(esr); pt_regs_write_reg(regs, rt, arch_timer_read_counter()); arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); } static void cntfrq_read_handler(unsigned long esr, struct pt_regs *regs) { int rt = ESR_ELx_SYS64_ISS_RT(esr); pt_regs_write_reg(regs, rt, arch_timer_get_rate()); arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); } static void mrs_handler(unsigned long esr, struct pt_regs *regs) { u32 sysreg, rt; rt = ESR_ELx_SYS64_ISS_RT(esr); sysreg = esr_sys64_to_sysreg(esr); if (do_emulate_mrs(regs, sysreg, rt) != 0) force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc, 0); } static void wfi_handler(unsigned long esr, struct pt_regs *regs) { arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); } struct sys64_hook { unsigned long esr_mask; unsigned long esr_val; void (*handler)(unsigned long esr, struct pt_regs *regs); }; static const struct sys64_hook sys64_hooks[] = { { .esr_mask = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_MASK, .esr_val = ESR_ELx_SYS64_ISS_EL0_CACHE_OP_VAL, .handler = user_cache_maint_handler, }, { /* Trap read access to CTR_EL0 */ .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, .esr_val = ESR_ELx_SYS64_ISS_SYS_CTR_READ, .handler = ctr_read_handler, }, { /* Trap read access to CNTVCT_EL0 */ .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTVCT, .handler = cntvct_read_handler, }, { /* Trap read access to CNTFRQ_EL0 */ .esr_mask = ESR_ELx_SYS64_ISS_SYS_OP_MASK, .esr_val = ESR_ELx_SYS64_ISS_SYS_CNTFRQ, .handler = cntfrq_read_handler, }, { /* Trap read access to CPUID registers */ .esr_mask = ESR_ELx_SYS64_ISS_SYS_MRS_OP_MASK, .esr_val = ESR_ELx_SYS64_ISS_SYS_MRS_OP_VAL, .handler = mrs_handler, }, { /* Trap WFI instructions executed in userspace */ .esr_mask = ESR_ELx_WFx_MASK, .esr_val = ESR_ELx_WFx_WFI_VAL, .handler = wfi_handler, }, {}, }; #ifdef CONFIG_COMPAT static bool cp15_cond_valid(unsigned long esr, struct pt_regs *regs) { int cond; /* Only a T32 instruction can trap without CV being set */ if (!(esr & ESR_ELx_CV)) { u32 it; it = compat_get_it_state(regs); if (!it) return true; cond = it >> 4; } else { cond = (esr & ESR_ELx_COND_MASK) >> ESR_ELx_COND_SHIFT; } return aarch32_opcode_cond_checks[cond](regs->pstate); } static void compat_cntfrq_read_handler(unsigned long esr, struct pt_regs *regs) { int reg = (esr & ESR_ELx_CP15_32_ISS_RT_MASK) >> ESR_ELx_CP15_32_ISS_RT_SHIFT; pt_regs_write_reg(regs, reg, arch_timer_get_rate()); arm64_skip_faulting_instruction(regs, 4); } static const struct sys64_hook cp15_32_hooks[] = { { .esr_mask = ESR_ELx_CP15_32_ISS_SYS_MASK, .esr_val = ESR_ELx_CP15_32_ISS_SYS_CNTFRQ, .handler = compat_cntfrq_read_handler, }, {}, }; static void compat_cntvct_read_handler(unsigned long esr, struct pt_regs *regs) { int rt = (esr & ESR_ELx_CP15_64_ISS_RT_MASK) >> ESR_ELx_CP15_64_ISS_RT_SHIFT; int rt2 = (esr & ESR_ELx_CP15_64_ISS_RT2_MASK) >> ESR_ELx_CP15_64_ISS_RT2_SHIFT; u64 val = arch_timer_read_counter(); pt_regs_write_reg(regs, rt, lower_32_bits(val)); pt_regs_write_reg(regs, rt2, upper_32_bits(val)); arm64_skip_faulting_instruction(regs, 4); } static const struct sys64_hook cp15_64_hooks[] = { { .esr_mask = ESR_ELx_CP15_64_ISS_SYS_MASK, .esr_val = ESR_ELx_CP15_64_ISS_SYS_CNTVCT, .handler = compat_cntvct_read_handler, }, {}, }; void do_el0_cp15(unsigned long esr, struct pt_regs *regs) { const struct sys64_hook *hook, *hook_base; if (!cp15_cond_valid(esr, regs)) { /* * There is no T16 variant of a CP access, so we * always advance PC by 4 bytes. */ arm64_skip_faulting_instruction(regs, 4); return; } switch (ESR_ELx_EC(esr)) { case ESR_ELx_EC_CP15_32: hook_base = cp15_32_hooks; break; case ESR_ELx_EC_CP15_64: hook_base = cp15_64_hooks; break; default: do_el0_undef(regs, esr); return; } for (hook = hook_base; hook->handler; hook++) if ((hook->esr_mask & esr) == hook->esr_val) { hook->handler(esr, regs); return; } /* * New cp15 instructions may previously have been undefined at * EL0. Fall back to our usual undefined instruction handler * so that we handle these consistently. */ do_el0_undef(regs, esr); } #endif void do_el0_sys(unsigned long esr, struct pt_regs *regs) { const struct sys64_hook *hook; for (hook = sys64_hooks; hook->handler; hook++) if ((hook->esr_mask & esr) == hook->esr_val) { hook->handler(esr, regs); return; } /* * New SYS instructions may previously have been undefined at EL0. Fall * back to our usual undefined instruction handler so that we handle * these consistently. */ do_el0_undef(regs, esr); } static const char *esr_class_str[] = { [0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC", [ESR_ELx_EC_UNKNOWN] = "Unknown/Uncategorized", [ESR_ELx_EC_WFx] = "WFI/WFE", [ESR_ELx_EC_CP15_32] = "CP15 MCR/MRC", [ESR_ELx_EC_CP15_64] = "CP15 MCRR/MRRC", [ESR_ELx_EC_CP14_MR] = "CP14 MCR/MRC", [ESR_ELx_EC_CP14_LS] = "CP14 LDC/STC", [ESR_ELx_EC_FP_ASIMD] = "ASIMD", [ESR_ELx_EC_CP10_ID] = "CP10 MRC/VMRS", [ESR_ELx_EC_PAC] = "PAC", [ESR_ELx_EC_CP14_64] = "CP14 MCRR/MRRC", [ESR_ELx_EC_BTI] = "BTI", [ESR_ELx_EC_ILL] = "PSTATE.IL", [ESR_ELx_EC_SVC32] = "SVC (AArch32)", [ESR_ELx_EC_HVC32] = "HVC (AArch32)", [ESR_ELx_EC_SMC32] = "SMC (AArch32)", [ESR_ELx_EC_SVC64] = "SVC (AArch64)", [ESR_ELx_EC_HVC64] = "HVC (AArch64)", [ESR_ELx_EC_SMC64] = "SMC (AArch64)", [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)", [ESR_ELx_EC_SVE] = "SVE", [ESR_ELx_EC_ERET] = "ERET/ERETAA/ERETAB", [ESR_ELx_EC_FPAC] = "FPAC", [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF", [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)", [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)", [ESR_ELx_EC_PC_ALIGN] = "PC Alignment", [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)", [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)", [ESR_ELx_EC_SP_ALIGN] = "SP Alignment", [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)", [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)", [ESR_ELx_EC_SERROR] = "SError", [ESR_ELx_EC_BREAKPT_LOW] = "Breakpoint (lower EL)", [ESR_ELx_EC_BREAKPT_CUR] = "Breakpoint (current EL)", [ESR_ELx_EC_SOFTSTP_LOW] = "Software Step (lower EL)", [ESR_ELx_EC_SOFTSTP_CUR] = "Software Step (current EL)", [ESR_ELx_EC_WATCHPT_LOW] = "Watchpoint (lower EL)", [ESR_ELx_EC_WATCHPT_CUR] = "Watchpoint (current EL)", [ESR_ELx_EC_BKPT32] = "BKPT (AArch32)", [ESR_ELx_EC_VECTOR32] = "Vector catch (AArch32)", [ESR_ELx_EC_BRK64] = "BRK (AArch64)", }; const char *esr_get_class_string(unsigned long esr) { return esr_class_str[ESR_ELx_EC(esr)]; } /* * bad_el0_sync handles unexpected, but potentially recoverable synchronous * exceptions taken from EL0. */ void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr) { unsigned long pc = instruction_pointer(regs); current->thread.fault_address = 0; current->thread.fault_code = esr; arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, "Bad EL0 synchronous exception"); } #ifdef CONFIG_VMAP_STACK DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack) __aligned(16); void panic_bad_stack(struct pt_regs *regs, unsigned long esr, unsigned long far) { unsigned long tsk_stk = (unsigned long)current->stack; unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr); unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); console_verbose(); pr_emerg("Insufficient stack space to handle exception!"); pr_emerg("ESR: 0x%016lx -- %s\n", esr, esr_get_class_string(esr)); pr_emerg("FAR: 0x%016lx\n", far); pr_emerg("Task stack: [0x%016lx..0x%016lx]\n", tsk_stk, tsk_stk + THREAD_SIZE); pr_emerg("IRQ stack: [0x%016lx..0x%016lx]\n", irq_stk, irq_stk + IRQ_STACK_SIZE); pr_emerg("Overflow stack: [0x%016lx..0x%016lx]\n", ovf_stk, ovf_stk + OVERFLOW_STACK_SIZE); __show_regs(regs); /* * We use nmi_panic to limit the potential for recusive overflows, and * to get a better stack trace. */ nmi_panic(NULL, "kernel stack overflow"); cpu_park_loop(); } #endif void __noreturn arm64_serror_panic(struct pt_regs *regs, unsigned long esr) { console_verbose(); pr_crit("SError Interrupt on CPU%d, code 0x%016lx -- %s\n", smp_processor_id(), esr, esr_get_class_string(esr)); if (regs) __show_regs(regs); nmi_panic(regs, "Asynchronous SError Interrupt"); cpu_park_loop(); unreachable(); } bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned long esr) { unsigned long aet = arm64_ras_serror_get_severity(esr); switch (aet) { case ESR_ELx_AET_CE: /* corrected error */ case ESR_ELx_AET_UEO: /* restartable, not yet consumed */ /* * The CPU can make progress. We may take UEO again as * a more severe error. */ return false; case ESR_ELx_AET_UEU: /* Uncorrected Unrecoverable */ case ESR_ELx_AET_UER: /* Uncorrected Recoverable */ /* * The CPU can't make progress. The exception may have * been imprecise. * * Neoverse-N1 #1349291 means a non-KVM SError reported as * Unrecoverable should be treated as Uncontainable. We * call arm64_serror_panic() in both cases. */ return true; case ESR_ELx_AET_UC: /* Uncontainable or Uncategorized error */ default: /* Error has been silently propagated */ arm64_serror_panic(regs, esr); } } void do_serror(struct pt_regs *regs, unsigned long esr) { /* non-RAS errors are not containable */ if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr)) arm64_serror_panic(regs, esr); } /* GENERIC_BUG traps */ int is_valid_bugaddr(unsigned long addr) { /* * bug_handler() only called for BRK #BUG_BRK_IMM. * So the answer is trivial -- any spurious instances with no * bug table entry will be rejected by report_bug() and passed * back to the debug-monitors code and handled as a fatal * unexpected debug exception. */ return 1; } static int bug_handler(struct pt_regs *regs, unsigned long esr) { switch (report_bug(regs->pc, regs)) { case BUG_TRAP_TYPE_BUG: die("Oops - BUG", regs, esr); break; case BUG_TRAP_TYPE_WARN: break; default: /* unknown/unrecognised bug trap type */ return DBG_HOOK_ERROR; } /* If thread survives, skip over the BUG instruction and continue: */ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); return DBG_HOOK_HANDLED; } static struct break_hook bug_break_hook = { .fn = bug_handler, .imm = BUG_BRK_IMM, }; static int reserved_fault_handler(struct pt_regs *regs, unsigned long esr) { pr_err("%s generated an invalid instruction at %pS!\n", "Kernel text patching", (void *)instruction_pointer(regs)); /* We cannot handle this */ return DBG_HOOK_ERROR; } static struct break_hook fault_break_hook = { .fn = reserved_fault_handler, .imm = FAULT_BRK_IMM, }; #ifdef CONFIG_KASAN_SW_TAGS #define KASAN_ESR_RECOVER 0x20 #define KASAN_ESR_WRITE 0x10 #define KASAN_ESR_SIZE_MASK 0x0f #define KASAN_ESR_SIZE(esr) (1 << ((esr) & KASAN_ESR_SIZE_MASK)) static int kasan_handler(struct pt_regs *regs, unsigned long esr) { bool recover = esr & KASAN_ESR_RECOVER; bool write = esr & KASAN_ESR_WRITE; size_t size = KASAN_ESR_SIZE(esr); u64 addr = regs->regs[0]; u64 pc = regs->pc; kasan_report(addr, size, write, pc); /* * The instrumentation allows to control whether we can proceed after * a crash was detected. This is done by passing the -recover flag to * the compiler. Disabling recovery allows to generate more compact * code. * * Unfortunately disabling recovery doesn't work for the kernel right * now. KASAN reporting is disabled in some contexts (for example when * the allocator accesses slab object metadata; this is controlled by * current->kasan_depth). All these accesses are detected by the tool, * even though the reports for them are not printed. * * This is something that might be fixed at some point in the future. */ if (!recover) die("Oops - KASAN", regs, esr); /* If thread survives, skip over the brk instruction and continue: */ arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); return DBG_HOOK_HANDLED; } static struct break_hook kasan_break_hook = { .fn = kasan_handler, .imm = KASAN_BRK_IMM, .mask = KASAN_BRK_MASK, }; #endif /* * Initial handler for AArch64 BRK exceptions * This handler only used until debug_traps_init(). */ int __init early_brk64(unsigned long addr, unsigned long esr, struct pt_regs *regs) { #ifdef CONFIG_KASAN_SW_TAGS unsigned long comment = esr & ESR_ELx_BRK64_ISS_COMMENT_MASK; if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; #endif return bug_handler(regs, esr) != DBG_HOOK_HANDLED; } void __init trap_init(void) { register_kernel_break_hook(&bug_break_hook); register_kernel_break_hook(&fault_break_hook); #ifdef CONFIG_KASAN_SW_TAGS register_kernel_break_hook(&kasan_break_hook); #endif debug_traps_init(); }