// 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 <linux/bug.h>
#include <linux/signal.h>
#include <linux/personality.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/kexec.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/sizes.h>
#include <linux/syscalls.h>
#include <linux/mm_types.h>
#include <linux/kasan.h>

#include <asm/atomic.h>
#include <asm/bug.h>
#include <asm/cpufeature.h>
#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/insn.h>
#include <asm/traps.h>
#include <asm/smp.h>
#include <asm/stack_pointer.h>
#include <asm/stacktrace.h>
#include <asm/exception.h>
#include <asm/system_misc.h>
#include <asm/sysreg.h>

static const char *handler[]= {
        "Synchronous Abort",
        "IRQ",
        "FIQ",
        "Error"
};

int show_unhandled_signals = 0;

static void dump_backtrace_entry(unsigned long where)
{
        printk(" %pS\n", (void *)where);
}

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);
}

void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
        struct stackframe frame;
        int skip = 0;

        pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);

        if (regs) {
                if (user_mode(regs))
                        return;
                skip = 1;
        }

        if (!tsk)
                tsk = current;

        if (!try_get_task_stack(tsk))
                return;

        if (tsk == current) {
                start_backtrace(&frame,
                                (unsigned long)__builtin_frame_address(0),
                                (unsigned long)dump_backtrace);
        } else {
                /*
                 * task blocked in __switch_to
                 */
                start_backtrace(&frame,
                                thread_saved_fp(tsk),
                                thread_saved_pc(tsk));
        }

        printk("Call trace:\n");
        do {
                /* skip until specified stack frame */
                if (!skip) {
                        dump_backtrace_entry(frame.pc);
                } else if (frame.fp == regs->regs[29]) {
                        skip = 0;
                        /*
                         * Mostly, this is the case where this function is
                         * called in panic/abort. As exception handler's
                         * stack frame does not contain the corresponding pc
                         * at which an exception has taken place, use regs->pc
                         * instead.
                         */
                        dump_backtrace_entry(regs->pc);
                }
        } while (!unwind_frame(tsk, &frame));

        put_task_stack(tsk);
}

void show_stack(struct task_struct *tsk, unsigned long *sp)
{
        dump_backtrace(NULL, tsk);
        barrier();
}

#ifdef CONFIG_PREEMPT
#define S_PREEMPT " PREEMPT"
#else
#define S_PREEMPT ""
#endif
#define S_SMP " SMP"

static int __die(const char *str, int err, struct pt_regs *regs)
{
        static int die_counter;
        int ret;

        pr_emerg("Internal error: %s: %x [#%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, int 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("Fatal exception in interrupt");
        if (panic_on_oops)
                panic("Fatal exception");

        raw_spin_unlock_irqrestore(&die_lock, flags);

        if (ret != NOTIFY_STOP)
                do_exit(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 int 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%08x, ", 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, void __user *addr,
                           const char *str)
{
        arm64_show_signal(signo, str);
        if (signo == SIGKILL)
                force_sig(SIGKILL);
        else
                force_sig_fault(signo, code, addr);
}

void arm64_force_sig_mceerr(int code, void __user *addr, short lsb,
                            const char *str)
{
        arm64_show_signal(SIGBUS, str);
        force_sig_mceerr(code, addr, lsb);
}

void arm64_force_sig_ptrace_errno_trap(int errno, void __user *addr,
                                       const char *str)
{
        arm64_show_signal(SIGTRAP, str);
        force_sig_ptrace_errno_trap(errno, addr);
}

void arm64_notify_die(const char *str, struct pt_regs *regs,
                      int signo, int sicode, void __user *addr,
                      int 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, addr, str);
        } else {
                die(str, regs, err);
        }
}

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);
}

static LIST_HEAD(undef_hook);
static DEFINE_RAW_SPINLOCK(undef_lock);

void register_undef_hook(struct undef_hook *hook)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&undef_lock, flags);
        list_add(&hook->node, &undef_hook);
        raw_spin_unlock_irqrestore(&undef_lock, flags);
}

void unregister_undef_hook(struct undef_hook *hook)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&undef_lock, flags);
        list_del(&hook->node);
        raw_spin_unlock_irqrestore(&undef_lock, flags);
}

static int call_undef_hook(struct pt_regs *regs)
{
        struct undef_hook *hook;
        unsigned long flags;
        u32 instr;
        int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
        void __user *pc = (void __user *)instruction_pointer(regs);

        if (!user_mode(regs)) {
                __le32 instr_le;
                if (probe_kernel_address((__force __le32 *)pc, instr_le))
                        goto exit;
                instr = le32_to_cpu(instr_le);
        } else if (compat_thumb_mode(regs)) {
                /* 16-bit Thumb instruction */
                __le16 instr_le;
                if (get_user(instr_le, (__le16 __user *)pc))
                        goto exit;
                instr = le16_to_cpu(instr_le);
                if (aarch32_insn_is_wide(instr)) {
                        u32 instr2;

                        if (get_user(instr_le, (__le16 __user *)(pc + 2)))
                                goto exit;
                        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))
                        goto exit;
                instr = le32_to_cpu(instr_le);
        }

        raw_spin_lock_irqsave(&undef_lock, flags);
        list_for_each_entry(hook, &undef_hook, node)
                if ((instr & hook->instr_mask) == hook->instr_val &&
                        (regs->pstate & hook->pstate_mask) == hook->pstate_val)
                        fn = hook->fn;

        raw_spin_unlock_irqrestore(&undef_lock, flags);
exit:
        return fn ? fn(regs, instr) : 1;
}

void force_signal_inject(int signal, int code, unsigned long address)
{
        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, (void __user *)address, 0);
}

/*
 * Set up process info to signal segmentation fault - called on access error.
 */
void arm64_notify_segfault(unsigned long addr)
{
        int code;

        down_read(&current->mm->mmap_sem);
        if (find_vma(current->mm, addr) == NULL)
                code = SEGV_MAPERR;
        else
                code = SEGV_ACCERR;
        up_read(&current->mm->mmap_sem);

        force_signal_inject(SIGSEGV, code, addr);
}

asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
{
        /* check for AArch32 breakpoint instructions */
        if (!aarch32_break_handler(regs))
                return;

        if (call_undef_hook(regs) == 0)
                return;

        BUG_ON(!user_mode(regs));
        force_signal_inject(SIGILL, ILL_ILLOPC, regs->pc);
}

#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 int esr, struct pt_regs *regs)
{
        unsigned long 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;

        address = untagged_addr(pt_regs_read_reg(regs, rt));

        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);
                return;
        }

        if (ret)
                arm64_notify_segfault(address);
        else
                arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}

static void ctr_read_handler(unsigned int 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);

        pt_regs_write_reg(regs, rt, val);

        arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}

static void cntvct_read_handler(unsigned int 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 int 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 int 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);
}

static void wfi_handler(unsigned int esr, struct pt_regs *regs)
{
        arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE);
}

struct sys64_hook {
        unsigned int esr_mask;
        unsigned int esr_val;
        void (*handler)(unsigned int esr, struct pt_regs *regs);
};

static 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
#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 bool cp15_cond_valid(unsigned int 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 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);
}

static void arm64_compat_skip_faulting_instruction(struct pt_regs *regs,
                                                   unsigned int sz)
{
        advance_itstate(regs);
        arm64_skip_faulting_instruction(regs, sz);
}

static void compat_cntfrq_read_handler(unsigned int 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_compat_skip_faulting_instruction(regs, 4);
}

static 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 int 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_compat_skip_faulting_instruction(regs, 4);
}

static 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,
        },
        {},
};

asmlinkage void __exception do_cp15instr(unsigned int esr, struct pt_regs *regs)
{
        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_compat_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_undefinstr(regs);
                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_undefinstr(regs);
}
#endif

asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
{
        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_undefinstr(regs);
}

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_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_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(u32 esr)
{
        return esr_class_str[ESR_ELx_EC(esr)];
}

/*
 * bad_mode handles the impossible case in the exception vector. This is always
 * fatal.
 */
asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
{
        console_verbose();

        pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
                handler[reason], smp_processor_id(), esr,
                esr_get_class_string(esr));

        local_daif_mask();
        panic("bad mode");
}

/*
 * bad_el0_sync handles unexpected, but potentially recoverable synchronous
 * exceptions taken from EL0. Unlike bad_mode, this returns.
 */
asmlinkage void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr)
{
        void __user *pc = (void __user *)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);

asmlinkage void handle_bad_stack(struct pt_regs *regs)
{
        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);
        unsigned int esr = read_sysreg(esr_el1);
        unsigned long far = read_sysreg(far_el1);

        console_verbose();
        pr_emerg("Insufficient stack space to handle exception!");

        pr_emerg("ESR: 0x%08x -- %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 + THREAD_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, u32 esr)
{
        console_verbose();

        pr_crit("SError Interrupt on CPU%d, code 0x%08x -- %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 int esr)
{
        u32 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);
        }
}

asmlinkage void do_serror(struct pt_regs *regs, unsigned int esr)
{
        const bool was_in_nmi = in_nmi();

        if (!was_in_nmi)
                nmi_enter();

        /* non-RAS errors are not containable */
        if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr))
                arm64_serror_panic(regs, esr);

        if (!was_in_nmi)
                nmi_exit();
}

void __pte_error(const char *file, int line, unsigned long val)
{
        pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
}

void __pmd_error(const char *file, int line, unsigned long val)
{
        pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
}

void __pud_error(const char *file, int line, unsigned long val)
{
        pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
}

void __pgd_error(const char *file, int line, unsigned long val)
{
        pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
}

/* 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 int esr)
{
        switch (report_bug(regs->pc, regs)) {
        case BUG_TRAP_TYPE_BUG:
                die("Oops - BUG", regs, 0);
                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,
};

#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 int 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, 0);

        /* 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 int esr,
                struct pt_regs *regs)
{
#ifdef CONFIG_KASAN_SW_TAGS
        unsigned int 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;
}

/* This registration must happen early, before debug_traps_init(). */
void __init trap_init(void)
{
        register_kernel_break_hook(&bug_break_hook);
#ifdef CONFIG_KASAN_SW_TAGS
        register_kernel_break_hook(&kasan_break_hook);
#endif
}