/*
 * Based on arch/arm/mm/fault.c
 *
 * Copyright (C) 1995  Linus Torvalds
 * Copyright (C) 1995-2004 Russell King
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/extable.h>
#include <linux/signal.h>
#include <linux/mm.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/page-flags.h>
#include <linux/sched/signal.h>
#include <linux/sched/debug.h>
#include <linux/highmem.h>
#include <linux/perf_event.h>
#include <linux/preempt.h>
#include <linux/hugetlb.h>

#include <asm/bug.h>
#include <asm/cmpxchg.h>
#include <asm/cpufeature.h>
#include <asm/exception.h>
#include <asm/debug-monitors.h>
#include <asm/esr.h>
#include <asm/sysreg.h>
#include <asm/system_misc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>

#include <acpi/ghes.h>

struct fault_info {
        int     (*fn)(unsigned long addr, unsigned int esr,
                      struct pt_regs *regs);
        int     sig;
        int     code;
        const char *name;
};

static const struct fault_info fault_info[];

static inline const struct fault_info *esr_to_fault_info(unsigned int esr)
{
        return fault_info + (esr & 63);
}

#ifdef CONFIG_KPROBES
static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
{
        int ret = 0;

        /* kprobe_running() needs smp_processor_id() */
        if (!user_mode(regs)) {
                preempt_disable();
                if (kprobe_running() && kprobe_fault_handler(regs, esr))
                        ret = 1;
                preempt_enable();
        }

        return ret;
}
#else
static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
{
        return 0;
}
#endif

static void data_abort_decode(unsigned int esr)
{
        pr_alert("Data abort info:\n");

        if (esr & ESR_ELx_ISV) {
                pr_alert("  Access size = %u byte(s)\n",
                         1U << ((esr & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT));
                pr_alert("  SSE = %lu, SRT = %lu\n",
                         (esr & ESR_ELx_SSE) >> ESR_ELx_SSE_SHIFT,
                         (esr & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT);
                pr_alert("  SF = %lu, AR = %lu\n",
                         (esr & ESR_ELx_SF) >> ESR_ELx_SF_SHIFT,
                         (esr & ESR_ELx_AR) >> ESR_ELx_AR_SHIFT);
        } else {
                pr_alert("  ISV = 0, ISS = 0x%08lx\n", esr & ESR_ELx_ISS_MASK);
        }

        pr_alert("  CM = %lu, WnR = %lu\n",
                 (esr & ESR_ELx_CM) >> ESR_ELx_CM_SHIFT,
                 (esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT);
}

/*
 * Decode mem abort information
 */
static void mem_abort_decode(unsigned int esr)
{
        pr_alert("Mem abort info:\n");

        pr_alert("  Exception class = %s, IL = %u bits\n",
                 esr_get_class_string(esr),
                 (esr & ESR_ELx_IL) ? 32 : 16);
        pr_alert("  SET = %lu, FnV = %lu\n",
                 (esr & ESR_ELx_SET_MASK) >> ESR_ELx_SET_SHIFT,
                 (esr & ESR_ELx_FnV) >> ESR_ELx_FnV_SHIFT);
        pr_alert("  EA = %lu, S1PTW = %lu\n",
                 (esr & ESR_ELx_EA) >> ESR_ELx_EA_SHIFT,
                 (esr & ESR_ELx_S1PTW) >> ESR_ELx_S1PTW_SHIFT);

        if (esr_is_data_abort(esr))
                data_abort_decode(esr);
}

/*
 * Dump out the page tables associated with 'addr' in the currently active mm.
 */
void show_pte(unsigned long addr)
{
        struct mm_struct *mm;
        pgd_t *pgd;

        if (addr < TASK_SIZE) {
                /* TTBR0 */
                mm = current->active_mm;
                if (mm == &init_mm) {
                        pr_alert("[%016lx] user address but active_mm is swapper\n",
                                 addr);
                        return;
                }
        } else if (addr >= VA_START) {
                /* TTBR1 */
                mm = &init_mm;
        } else {
                pr_alert("[%016lx] address between user and kernel address ranges\n",
                         addr);
                return;
        }

        pr_alert("%s pgtable: %luk pages, %u-bit VAs, pgd = %p\n",
                 mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K,
                 VA_BITS, mm->pgd);
        pgd = pgd_offset(mm, addr);
        pr_alert("[%016lx] *pgd=%016llx", addr, pgd_val(*pgd));

        do {
                pud_t *pud;
                pmd_t *pmd;
                pte_t *pte;

                if (pgd_none(*pgd) || pgd_bad(*pgd))
                        break;

                pud = pud_offset(pgd, addr);
                pr_cont(", *pud=%016llx", pud_val(*pud));
                if (pud_none(*pud) || pud_bad(*pud))
                        break;

                pmd = pmd_offset(pud, addr);
                pr_cont(", *pmd=%016llx", pmd_val(*pmd));
                if (pmd_none(*pmd) || pmd_bad(*pmd))
                        break;

                pte = pte_offset_map(pmd, addr);
                pr_cont(", *pte=%016llx", pte_val(*pte));
                pte_unmap(pte);
        } while(0);

        pr_cont("\n");
}

/*
 * This function sets the access flags (dirty, accessed), as well as write
 * permission, and only to a more permissive setting.
 *
 * It needs to cope with hardware update of the accessed/dirty state by other
 * agents in the system and can safely skip the __sync_icache_dcache() call as,
 * like set_pte_at(), the PTE is never changed from no-exec to exec here.
 *
 * Returns whether or not the PTE actually changed.
 */
int ptep_set_access_flags(struct vm_area_struct *vma,
                          unsigned long address, pte_t *ptep,
                          pte_t entry, int dirty)
{
        pteval_t old_pteval, pteval;

        if (pte_same(*ptep, entry))
                return 0;

        /* only preserve the access flags and write permission */
        pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY;

        /*
         * Setting the flags must be done atomically to avoid racing with the
         * hardware update of the access/dirty state. The PTE_RDONLY bit must
         * be set to the most permissive (lowest value) of *ptep and entry
         * (calculated as: a & b == ~(~a | ~b)).
         */
        pte_val(entry) ^= PTE_RDONLY;
        pteval = READ_ONCE(pte_val(*ptep));
        do {
                old_pteval = pteval;
                pteval ^= PTE_RDONLY;
                pteval |= pte_val(entry);
                pteval ^= PTE_RDONLY;
                pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
        } while (pteval != old_pteval);

        flush_tlb_fix_spurious_fault(vma, address);
        return 1;
}

static bool is_el1_instruction_abort(unsigned int esr)
{
        return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
}

static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs,
                                       unsigned long addr)
{
        unsigned int ec       = ESR_ELx_EC(esr);
        unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;

        if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR)
                return false;

        if (fsc_type == ESR_ELx_FSC_PERM)
                return true;

        if (addr < USER_DS && system_uses_ttbr0_pan())
                return fsc_type == ESR_ELx_FSC_FAULT &&
                        (regs->pstate & PSR_PAN_BIT);

        return false;
}

/*
 * The kernel tried to access some page that wasn't present.
 */
static void __do_kernel_fault(unsigned long addr, unsigned int esr,
                              struct pt_regs *regs)
{
        const char *msg;

        /*
         * Are we prepared to handle this kernel fault?
         * We are almost certainly not prepared to handle instruction faults.
         */
        if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
                return;

        /*
         * No handler, we'll have to terminate things with extreme prejudice.
         */
        bust_spinlocks(1);

        if (is_permission_fault(esr, regs, addr)) {
                if (esr & ESR_ELx_WNR)
                        msg = "write to read-only memory";
                else
                        msg = "read from unreadable memory";
        } else if (addr < PAGE_SIZE) {
                msg = "NULL pointer dereference";
        } else {
                msg = "paging request";
        }

        pr_alert("Unable to handle kernel %s at virtual address %08lx\n", msg,
                 addr);

        mem_abort_decode(esr);

        show_pte(addr);
        die("Oops", regs, esr);
        bust_spinlocks(0);
        do_exit(SIGKILL);
}

/*
 * Something tried to access memory that isn't in our memory map. User mode
 * accesses just cause a SIGSEGV
 */
static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
                            unsigned int esr, unsigned int sig, int code,
                            struct pt_regs *regs, int fault)
{
        struct siginfo si;
        const struct fault_info *inf;
        unsigned int lsb = 0;

        if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
                inf = esr_to_fault_info(esr);
                pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x",
                        tsk->comm, task_pid_nr(tsk), inf->name, sig,
                        addr, esr);
                print_vma_addr(KERN_CONT ", in ", regs->pc);
                pr_cont("\n");
                __show_regs(regs);
        }

        tsk->thread.fault_address = addr;
        tsk->thread.fault_code = esr;
        si.si_signo = sig;
        si.si_errno = 0;
        si.si_code = code;
        si.si_addr = (void __user *)addr;
        /*
         * Either small page or large page may be poisoned.
         * In other words, VM_FAULT_HWPOISON_LARGE and
         * VM_FAULT_HWPOISON are mutually exclusive.
         */
        if (fault & VM_FAULT_HWPOISON_LARGE)
                lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
        else if (fault & VM_FAULT_HWPOISON)
                lsb = PAGE_SHIFT;
        si.si_addr_lsb = lsb;

        force_sig_info(sig, &si, tsk);
}

static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
        struct task_struct *tsk = current;
        const struct fault_info *inf;

        /*
         * If we are in kernel mode at this point, we have no context to
         * handle this fault with.
         */
        if (user_mode(regs)) {
                inf = esr_to_fault_info(esr);
                __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs, 0);
        } else
                __do_kernel_fault(addr, esr, regs);
}

#define VM_FAULT_BADMAP         0x010000
#define VM_FAULT_BADACCESS      0x020000

static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
                           unsigned int mm_flags, unsigned long vm_flags,
                           struct task_struct *tsk)
{
        struct vm_area_struct *vma;
        int fault;

        vma = find_vma(mm, addr);
        fault = VM_FAULT_BADMAP;
        if (unlikely(!vma))
                goto out;
        if (unlikely(vma->vm_start > addr))
                goto check_stack;

        /*
         * Ok, we have a good vm_area for this memory access, so we can handle
         * it.
         */
good_area:
        /*
         * Check that the permissions on the VMA allow for the fault which
         * occurred.
         */
        if (!(vma->vm_flags & vm_flags)) {
                fault = VM_FAULT_BADACCESS;
                goto out;
        }

        return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);

check_stack:
        if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
                goto good_area;
out:
        return fault;
}

static bool is_el0_instruction_abort(unsigned int esr)
{
        return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
}

static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
                                   struct pt_regs *regs)
{
        struct task_struct *tsk;
        struct mm_struct *mm;
        int fault, sig, code, major = 0;
        unsigned long vm_flags = VM_READ | VM_WRITE;
        unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;

        if (notify_page_fault(regs, esr))
                return 0;

        tsk = current;
        mm  = tsk->mm;

        /*
         * If we're in an interrupt or have no user context, we must not take
         * the fault.
         */
        if (faulthandler_disabled() || !mm)
                goto no_context;

        if (user_mode(regs))
                mm_flags |= FAULT_FLAG_USER;

        if (is_el0_instruction_abort(esr)) {
                vm_flags = VM_EXEC;
        } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
                vm_flags = VM_WRITE;
                mm_flags |= FAULT_FLAG_WRITE;
        }

        if (addr < USER_DS && is_permission_fault(esr, regs, addr)) {
                /* regs->orig_addr_limit may be 0 if we entered from EL0 */
                if (regs->orig_addr_limit == KERNEL_DS)
                        die("Accessing user space memory with fs=KERNEL_DS", regs, esr);

                if (is_el1_instruction_abort(esr))
                        die("Attempting to execute userspace memory", regs, esr);

                if (!search_exception_tables(regs->pc))
                        die("Accessing user space memory outside uaccess.h routines", regs, esr);
        }

        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);

        /*
         * As per x86, we may deadlock here. However, since the kernel only
         * validly references user space from well defined areas of the code,
         * we can bug out early if this is from code which shouldn't.
         */
        if (!down_read_trylock(&mm->mmap_sem)) {
                if (!user_mode(regs) && !search_exception_tables(regs->pc))
                        goto no_context;
retry:
                down_read(&mm->mmap_sem);
        } else {
                /*
                 * The above down_read_trylock() might have succeeded in which
                 * case, we'll have missed the might_sleep() from down_read().
                 */
                might_sleep();
#ifdef CONFIG_DEBUG_VM
                if (!user_mode(regs) && !search_exception_tables(regs->pc))
                        goto no_context;
#endif
        }

        fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
        major |= fault & VM_FAULT_MAJOR;

        if (fault & VM_FAULT_RETRY) {
                /*
                 * If we need to retry but a fatal signal is pending,
                 * handle the signal first. We do not need to release
                 * the mmap_sem because it would already be released
                 * in __lock_page_or_retry in mm/filemap.c.
                 */
                if (fatal_signal_pending(current)) {
                        if (!user_mode(regs))
                                goto no_context;
                        return 0;
                }

                /*
                 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
                 * starvation.
                 */
                if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
                        mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
                        mm_flags |= FAULT_FLAG_TRIED;
                        goto retry;
                }
        }
        up_read(&mm->mmap_sem);

        /*
         * Handle the "normal" (no error) case first.
         */
        if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
                              VM_FAULT_BADACCESS)))) {
                /*
                 * Major/minor page fault accounting is only done
                 * once. If we go through a retry, it is extremely
                 * likely that the page will be found in page cache at
                 * that point.
                 */
                if (major) {
                        tsk->maj_flt++;
                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
                                      addr);
                } else {
                        tsk->min_flt++;
                        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
                                      addr);
                }

                return 0;
        }

        /*
         * If we are in kernel mode at this point, we have no context to
         * handle this fault with.
         */
        if (!user_mode(regs))
                goto no_context;

        if (fault & VM_FAULT_OOM) {
                /*
                 * We ran out of memory, call the OOM killer, and return to
                 * userspace (which will retry the fault, or kill us if we got
                 * oom-killed).
                 */
                pagefault_out_of_memory();
                return 0;
        }

        if (fault & VM_FAULT_SIGBUS) {
                /*
                 * We had some memory, but were unable to successfully fix up
                 * this page fault.
                 */
                sig = SIGBUS;
                code = BUS_ADRERR;
        } else if (fault & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) {
                sig = SIGBUS;
                code = BUS_MCEERR_AR;
        } else {
                /*
                 * Something tried to access memory that isn't in our memory
                 * map.
                 */
                sig = SIGSEGV;
                code = fault == VM_FAULT_BADACCESS ?
                        SEGV_ACCERR : SEGV_MAPERR;
        }

        __do_user_fault(tsk, addr, esr, sig, code, regs, fault);
        return 0;

no_context:
        __do_kernel_fault(addr, esr, regs);
        return 0;
}

/*
 * First Level Translation Fault Handler
 *
 * We enter here because the first level page table doesn't contain a valid
 * entry for the address.
 *
 * If the address is in kernel space (>= TASK_SIZE), then we are probably
 * faulting in the vmalloc() area.
 *
 * If the init_task's first level page tables contains the relevant entry, we
 * copy the it to this task.  If not, we send the process a signal, fixup the
 * exception, or oops the kernel.
 *
 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
 * or a critical region, and should only copy the information from the master
 * page table, nothing more.
 */
static int __kprobes do_translation_fault(unsigned long addr,
                                          unsigned int esr,
                                          struct pt_regs *regs)
{
        if (addr < TASK_SIZE)
                return do_page_fault(addr, esr, regs);

        do_bad_area(addr, esr, regs);
        return 0;
}

static int do_alignment_fault(unsigned long addr, unsigned int esr,
                              struct pt_regs *regs)
{
        do_bad_area(addr, esr, regs);
        return 0;
}

/*
 * This abort handler always returns "fault".
 */
static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
        return 1;
}

/*
 * This abort handler deals with Synchronous External Abort.
 * It calls notifiers, and then returns "fault".
 */
static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
{
        struct siginfo info;
        const struct fault_info *inf;
        int ret = 0;

        inf = esr_to_fault_info(esr);
        pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
                inf->name, esr, addr);

        /*
         * Synchronous aborts may interrupt code which had interrupts masked.
         * Before calling out into the wider kernel tell the interested
         * subsystems.
         */
        if (IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
                if (interrupts_enabled(regs))
                        nmi_enter();

                ret = ghes_notify_sea();

                if (interrupts_enabled(regs))
                        nmi_exit();
        }

        info.si_signo = SIGBUS;
        info.si_errno = 0;
        info.si_code  = 0;
        if (esr & ESR_ELx_FnV)
                info.si_addr = NULL;
        else
                info.si_addr  = (void __user *)addr;
        arm64_notify_die("", regs, &info, esr);

        return ret;
}

static const struct fault_info fault_info[] = {
        { do_bad,               SIGBUS,  0,             "ttbr address size fault"       },
        { do_bad,               SIGBUS,  0,             "level 1 address size fault"    },
        { do_bad,               SIGBUS,  0,             "level 2 address size fault"    },
        { do_bad,               SIGBUS,  0,             "level 3 address size fault"    },
        { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 0 translation fault"     },
        { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 1 translation fault"     },
        { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 2 translation fault"     },
        { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 3 translation fault"     },
        { do_bad,               SIGBUS,  0,             "unknown 8"                     },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 access flag fault"     },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 access flag fault"     },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 access flag fault"     },
        { do_bad,               SIGBUS,  0,             "unknown 12"                    },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 permission fault"      },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 permission fault"      },
        { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 permission fault"      },
        { do_sea,               SIGBUS,  0,             "synchronous external abort"    },
        { do_bad,               SIGBUS,  0,             "unknown 17"                    },
        { do_bad,               SIGBUS,  0,             "unknown 18"                    },
        { do_bad,               SIGBUS,  0,             "unknown 19"                    },
        { do_sea,               SIGBUS,  0,             "level 0 (translation table walk)"      },
        { do_sea,               SIGBUS,  0,             "level 1 (translation table walk)"      },
        { do_sea,               SIGBUS,  0,             "level 2 (translation table walk)"      },
        { do_sea,               SIGBUS,  0,             "level 3 (translation table walk)"      },
        { do_sea,               SIGBUS,  0,             "synchronous parity or ECC error" },
        { do_bad,               SIGBUS,  0,             "unknown 25"                    },
        { do_bad,               SIGBUS,  0,             "unknown 26"                    },
        { do_bad,               SIGBUS,  0,             "unknown 27"                    },
        { do_sea,               SIGBUS,  0,             "level 0 synchronous parity error (translation table walk)"     },
        { do_sea,               SIGBUS,  0,             "level 1 synchronous parity error (translation table walk)"     },
        { do_sea,               SIGBUS,  0,             "level 2 synchronous parity error (translation table walk)"     },
        { do_sea,               SIGBUS,  0,             "level 3 synchronous parity error (translation table walk)"     },
        { do_bad,               SIGBUS,  0,             "unknown 32"                    },
        { do_alignment_fault,   SIGBUS,  BUS_ADRALN,    "alignment fault"               },
        { do_bad,               SIGBUS,  0,             "unknown 34"                    },
        { do_bad,               SIGBUS,  0,             "unknown 35"                    },
        { do_bad,               SIGBUS,  0,             "unknown 36"                    },
        { do_bad,               SIGBUS,  0,             "unknown 37"                    },
        { do_bad,               SIGBUS,  0,             "unknown 38"                    },
        { do_bad,               SIGBUS,  0,             "unknown 39"                    },
        { do_bad,               SIGBUS,  0,             "unknown 40"                    },
        { do_bad,               SIGBUS,  0,             "unknown 41"                    },
        { do_bad,               SIGBUS,  0,             "unknown 42"                    },
        { do_bad,               SIGBUS,  0,             "unknown 43"                    },
        { do_bad,               SIGBUS,  0,             "unknown 44"                    },
        { do_bad,               SIGBUS,  0,             "unknown 45"                    },
        { do_bad,               SIGBUS,  0,             "unknown 46"                    },
        { do_bad,               SIGBUS,  0,             "unknown 47"                    },
        { do_bad,               SIGBUS,  0,             "TLB conflict abort"            },
        { do_bad,               SIGBUS,  0,             "unknown 49"                    },
        { do_bad,               SIGBUS,  0,             "unknown 50"                    },
        { do_bad,               SIGBUS,  0,             "unknown 51"                    },
        { do_bad,               SIGBUS,  0,             "implementation fault (lockdown abort)" },
        { do_bad,               SIGBUS,  0,             "implementation fault (unsupported exclusive)" },
        { do_bad,               SIGBUS,  0,             "unknown 54"                    },
        { do_bad,               SIGBUS,  0,             "unknown 55"                    },
        { do_bad,               SIGBUS,  0,             "unknown 56"                    },
        { do_bad,               SIGBUS,  0,             "unknown 57"                    },
        { do_bad,               SIGBUS,  0,             "unknown 58"                    },
        { do_bad,               SIGBUS,  0,             "unknown 59"                    },
        { do_bad,               SIGBUS,  0,             "unknown 60"                    },
        { do_bad,               SIGBUS,  0,             "section domain fault"          },
        { do_bad,               SIGBUS,  0,             "page domain fault"             },
        { do_bad,               SIGBUS,  0,             "unknown 63"                    },
};

/*
 * Handle Synchronous External Aborts that occur in a guest kernel.
 *
 * The return value will be zero if the SEA was successfully handled
 * and non-zero if there was an error processing the error or there was
 * no error to process.
 */
int handle_guest_sea(phys_addr_t addr, unsigned int esr)
{
        int ret = -ENOENT;

        if (IS_ENABLED(CONFIG_ACPI_APEI_SEA))
                ret = ghes_notify_sea();

        return ret;
}

/*
 * Dispatch a data abort to the relevant handler.
 */
asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
                                         struct pt_regs *regs)
{
        const struct fault_info *inf = esr_to_fault_info(esr);
        struct siginfo info;

        if (!inf->fn(addr, esr, regs))
                return;

        pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
                 inf->name, esr, addr);

        mem_abort_decode(esr);

        info.si_signo = inf->sig;
        info.si_errno = 0;
        info.si_code  = inf->code;
        info.si_addr  = (void __user *)addr;
        arm64_notify_die("", regs, &info, esr);
}

/*
 * Handle stack alignment exceptions.
 */
asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
                                           unsigned int esr,
                                           struct pt_regs *regs)
{
        struct siginfo info;
        struct task_struct *tsk = current;

        if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
                pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
                                    tsk->comm, task_pid_nr(tsk),
                                    esr_get_class_string(esr), (void *)regs->pc,
                                    (void *)regs->sp);

        info.si_signo = SIGBUS;
        info.si_errno = 0;
        info.si_code  = BUS_ADRALN;
        info.si_addr  = (void __user *)addr;
        arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
}

int __init early_brk64(unsigned long addr, unsigned int esr,
                       struct pt_regs *regs);

/*
 * __refdata because early_brk64 is __init, but the reference to it is
 * clobbered at arch_initcall time.
 * See traps.c and debug-monitors.c:debug_traps_init().
 */
static struct fault_info __refdata debug_fault_info[] = {
        { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware breakpoint"   },
        { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware single-step"  },
        { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware watchpoint"   },
        { do_bad,       SIGBUS,         0,              "unknown 3"             },
        { do_bad,       SIGTRAP,        TRAP_BRKPT,     "aarch32 BKPT"          },
        { do_bad,       SIGTRAP,        0,              "aarch32 vector catch"  },
        { early_brk64,  SIGTRAP,        TRAP_BRKPT,     "aarch64 BRK"           },
        { do_bad,       SIGBUS,         0,              "unknown 7"             },
};

void __init hook_debug_fault_code(int nr,
                                  int (*fn)(unsigned long, unsigned int, struct pt_regs *),
                                  int sig, int code, const char *name)
{
        BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));

        debug_fault_info[nr].fn         = fn;
        debug_fault_info[nr].sig        = sig;
        debug_fault_info[nr].code       = code;
        debug_fault_info[nr].name       = name;
}

asmlinkage int __exception do_debug_exception(unsigned long addr,
                                              unsigned int esr,
                                              struct pt_regs *regs)
{
        const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
        struct siginfo info;
        int rv;

        /*
         * Tell lockdep we disabled irqs in entry.S. Do nothing if they were
         * already disabled to preserve the last enabled/disabled addresses.
         */
        if (interrupts_enabled(regs))
                trace_hardirqs_off();

        if (!inf->fn(addr, esr, regs)) {
                rv = 1;
        } else {
                pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
                         inf->name, esr, addr);

                info.si_signo = inf->sig;
                info.si_errno = 0;
                info.si_code  = inf->code;
                info.si_addr  = (void __user *)addr;
                arm64_notify_die("", regs, &info, 0);
                rv = 0;
        }

        if (interrupts_enabled(regs))
                trace_hardirqs_on();

        return rv;
}
NOKPROBE_SYMBOL(do_debug_exception);

#ifdef CONFIG_ARM64_PAN
int cpu_enable_pan(void *__unused)
{
        /*
         * We modify PSTATE. This won't work from irq context as the PSTATE
         * is discarded once we return from the exception.
         */
        WARN_ON_ONCE(in_interrupt());

        config_sctlr_el1(SCTLR_EL1_SPAN, 0);
        asm(SET_PSTATE_PAN(1));
        return 0;
}
#endif /* CONFIG_ARM64_PAN */