/*
 * arch/sh/mm/tlb-flush_64.c
 *
 * Copyright (C) 2000, 2001  Paolo Alberelli
 * Copyright (C) 2003  Richard Curnow (/proc/tlb, bug fixes)
 * Copyright (C) 2003  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/signal.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/tlb.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/mmu_context.h>

extern void die(const char *,struct pt_regs *,long);

#define PFLAG(val,flag)   (( (val) & (flag) ) ? #flag : "" )
#define PPROT(flag) PFLAG(pgprot_val(prot),flag)

static inline void print_prots(pgprot_t prot)
{
        printk("prot is 0x%08lx\n",pgprot_val(prot));

        printk("%s %s %s %s %s\n",PPROT(_PAGE_SHARED),PPROT(_PAGE_READ),
               PPROT(_PAGE_EXECUTE),PPROT(_PAGE_WRITE),PPROT(_PAGE_USER));
}

static inline void print_vma(struct vm_area_struct *vma)
{
        printk("vma start 0x%08lx\n", vma->vm_start);
        printk("vma end   0x%08lx\n", vma->vm_end);

        print_prots(vma->vm_page_prot);
        printk("vm_flags 0x%08lx\n", vma->vm_flags);
}

static inline void print_task(struct task_struct *tsk)
{
        printk("Task pid %d\n", task_pid_nr(tsk));
}

static pte_t *lookup_pte(struct mm_struct *mm, unsigned long address)
{
        pgd_t *dir;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
        pte_t entry;

        dir = pgd_offset(mm, address);
        if (pgd_none(*dir))
                return NULL;

        pud = pud_offset(dir, address);
        if (pud_none(*pud))
                return NULL;

        pmd = pmd_offset(pud, address);
        if (pmd_none(*pmd))
                return NULL;

        pte = pte_offset_kernel(pmd, address);
        entry = *pte;
        if (pte_none(entry) || !pte_present(entry))
                return NULL;

        return pte;
}

/*
 * This routine handles page faults.  It determines the address,
 * and the problem, and then passes it off to one of the appropriate
 * routines.
 */
asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
                              unsigned long textaccess, unsigned long address)
{
        struct task_struct *tsk;
        struct mm_struct *mm;
        struct vm_area_struct * vma;
        const struct exception_table_entry *fixup;
        pte_t *pte;
        int fault;

        /* SIM
         * Note this is now called with interrupts still disabled
         * This is to cope with being called for a missing IO port
         * address with interrupts disabled. This should be fixed as
         * soon as we have a better 'fast path' miss handler.
         *
         * Plus take care how you try and debug this stuff.
         * For example, writing debug data to a port which you
         * have just faulted on is not going to work.
         */

        tsk = current;
        mm = tsk->mm;

        /* Not an IO address, so reenable interrupts */
        local_irq_enable();

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

        /* TLB misses upon some cache flushes get done under cli() */
        down_read(&mm->mmap_sem);

        vma = find_vma(mm, address);

        if (!vma) {
#ifdef DEBUG_FAULT
                print_task(tsk);
                printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
                       __func__, __LINE__,
                       address,regs->pc,textaccess,writeaccess);
                show_regs(regs);
#endif
                goto bad_area;
        }
        if (vma->vm_start <= address) {
                goto good_area;
        }

        if (!(vma->vm_flags & VM_GROWSDOWN)) {
#ifdef DEBUG_FAULT
                print_task(tsk);
                printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
                       __func__, __LINE__,
                       address,regs->pc,textaccess,writeaccess);
                show_regs(regs);

                print_vma(vma);
#endif
                goto bad_area;
        }
        if (expand_stack(vma, address)) {
#ifdef DEBUG_FAULT
                print_task(tsk);
                printk("%s:%d fault, address is 0x%08x PC %016Lx textaccess %d writeaccess %d\n",
                       __func__, __LINE__,
                       address,regs->pc,textaccess,writeaccess);
                show_regs(regs);
#endif
                goto bad_area;
        }
/*
 * Ok, we have a good vm_area for this memory access, so
 * we can handle it..
 */
good_area:
        if (textaccess) {
                if (!(vma->vm_flags & VM_EXEC))
                        goto bad_area;
        } else {
                if (writeaccess) {
                        if (!(vma->vm_flags & VM_WRITE))
                                goto bad_area;
                } else {
                        if (!(vma->vm_flags & VM_READ))
                                goto bad_area;
                }
        }

        /*
         * If for any reason at all we couldn't handle the fault,
         * make sure we exit gracefully rather than endlessly redo
         * the fault.
         */
survive:
        fault = handle_mm_fault(mm, vma, address, writeaccess);
        if (unlikely(fault & VM_FAULT_ERROR)) {
                if (fault & VM_FAULT_OOM)
                        goto out_of_memory;
                else if (fault & VM_FAULT_SIGBUS)
                        goto do_sigbus;
                BUG();
        }
        if (fault & VM_FAULT_MAJOR)
                tsk->maj_flt++;
        else
                tsk->min_flt++;

        /* If we get here, the page fault has been handled.  Do the TLB refill
           now from the newly-setup PTE, to avoid having to fault again right
           away on the same instruction. */
        pte = lookup_pte (mm, address);
        if (!pte) {
                /* From empirical evidence, we can get here, due to
                   !pte_present(pte).  (e.g. if a swap-in occurs, and the page
                   is swapped back out again before the process that wanted it
                   gets rescheduled?) */
                goto no_pte;
        }

        __do_tlb_refill(address, textaccess, pte);

no_pte:

        up_read(&mm->mmap_sem);
        return;

/*
 * Something tried to access memory that isn't in our memory map..
 * Fix it, but check if it's kernel or user first..
 */
bad_area:
#ifdef DEBUG_FAULT
        printk("fault:bad area\n");
#endif
        up_read(&mm->mmap_sem);

        if (user_mode(regs)) {
                static int count=0;
                siginfo_t info;
                if (count < 4) {
                        /* This is really to help debug faults when starting
                         * usermode, so only need a few */
                        count++;
                        printk("user mode bad_area address=%08lx pid=%d (%s) pc=%08lx\n",
                                address, task_pid_nr(current), current->comm,
                                (unsigned long) regs->pc);
#if 0
                        show_regs(regs);
#endif
                }
                if (is_global_init(tsk)) {
                        panic("INIT had user mode bad_area\n");
                }
                tsk->thread.address = address;
                tsk->thread.error_code = writeaccess;
                info.si_signo = SIGSEGV;
                info.si_errno = 0;
                info.si_addr = (void *) address;
                force_sig_info(SIGSEGV, &info, tsk);
                return;
        }

no_context:
#ifdef DEBUG_FAULT
        printk("fault:No context\n");
#endif
        /* Are we prepared to handle this kernel fault?  */
        fixup = search_exception_tables(regs->pc);
        if (fixup) {
                regs->pc = fixup->fixup;
                return;
        }

/*
 * Oops. The kernel tried to access some bad page. We'll have to
 * terminate things with extreme prejudice.
 *
 */
        if (address < PAGE_SIZE)
                printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
        else
                printk(KERN_ALERT "Unable to handle kernel paging request");
        printk(" at virtual address %08lx\n", address);
        printk(KERN_ALERT "pc = %08Lx%08Lx\n", regs->pc >> 32, regs->pc & 0xffffffff);
        die("Oops", regs, writeaccess);
        do_exit(SIGKILL);

/*
 * We ran out of memory, or some other thing happened to us that made
 * us unable to handle the page fault gracefully.
 */
out_of_memory:
        if (is_global_init(current)) {
                panic("INIT out of memory\n");
                yield();
                goto survive;
        }
        printk("fault:Out of memory\n");
        up_read(&mm->mmap_sem);
        if (is_global_init(current)) {
                yield();
                down_read(&mm->mmap_sem);
                goto survive;
        }
        printk("VM: killing process %s\n", tsk->comm);
        if (user_mode(regs))
                do_group_exit(SIGKILL);
        goto no_context;

do_sigbus:
        printk("fault:Do sigbus\n");
        up_read(&mm->mmap_sem);

        /*
         * Send a sigbus, regardless of whether we were in kernel
         * or user mode.
         */
        tsk->thread.address = address;
        tsk->thread.error_code = writeaccess;
        tsk->thread.trap_no = 14;
        force_sig(SIGBUS, tsk);

        /* Kernel mode? Handle exceptions or die */
        if (!user_mode(regs))
                goto no_context;
}

void update_mmu_cache(struct vm_area_struct * vma,
                        unsigned long address, pte_t pte)
{
        /*
         * This appears to get called once for every pte entry that gets
         * established => I don't think it's efficient to try refilling the
         * TLBs with the pages - some may not get accessed even.  Also, for
         * executable pages, it is impossible to determine reliably here which
         * TLB they should be mapped into (or both even).
         *
         * So, just do nothing here and handle faults on demand.  In the
         * TLBMISS handling case, the refill is now done anyway after the pte
         * has been fixed up, so that deals with most useful cases.
         */
}

void local_flush_tlb_one(unsigned long asid, unsigned long page)
{
        unsigned long long match, pteh=0, lpage;
        unsigned long tlb;

        /*
         * Sign-extend based on neff.
         */
        lpage = (page & NEFF_SIGN) ? (page | NEFF_MASK) : page;
        match = (asid << PTEH_ASID_SHIFT) | PTEH_VALID;
        match |= lpage;

        for_each_itlb_entry(tlb) {
                asm volatile ("getcfg   %1, 0, %0"
                              : "=r" (pteh)
                              : "r" (tlb) );

                if (pteh == match) {
                        __flush_tlb_slot(tlb);
                        break;
                }
        }

        for_each_dtlb_entry(tlb) {
                asm volatile ("getcfg   %1, 0, %0"
                              : "=r" (pteh)
                              : "r" (tlb) );

                if (pteh == match) {
                        __flush_tlb_slot(tlb);
                        break;
                }

        }
}

void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
{
        unsigned long flags;

        if (vma->vm_mm) {
                page &= PAGE_MASK;
                local_irq_save(flags);
                local_flush_tlb_one(get_asid(), page);
                local_irq_restore(flags);
        }
}

void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
                           unsigned long end)
{
        unsigned long flags;
        unsigned long long match, pteh=0, pteh_epn, pteh_low;
        unsigned long tlb;
        unsigned int cpu = smp_processor_id();
        struct mm_struct *mm;

        mm = vma->vm_mm;
        if (cpu_context(cpu, mm) == NO_CONTEXT)
                return;

        local_irq_save(flags);

        start &= PAGE_MASK;
        end &= PAGE_MASK;

        match = (cpu_asid(cpu, mm) << PTEH_ASID_SHIFT) | PTEH_VALID;

        /* Flush ITLB */
        for_each_itlb_entry(tlb) {
                asm volatile ("getcfg   %1, 0, %0"
                              : "=r" (pteh)
                              : "r" (tlb) );

                pteh_epn = pteh & PAGE_MASK;
                pteh_low = pteh & ~PAGE_MASK;

                if (pteh_low == match && pteh_epn >= start && pteh_epn <= end)
                        __flush_tlb_slot(tlb);
        }

        /* Flush DTLB */
        for_each_dtlb_entry(tlb) {
                asm volatile ("getcfg   %1, 0, %0"
                              : "=r" (pteh)
                              : "r" (tlb) );

                pteh_epn = pteh & PAGE_MASK;
                pteh_low = pteh & ~PAGE_MASK;

                if (pteh_low == match && pteh_epn >= start && pteh_epn <= end)
                        __flush_tlb_slot(tlb);
        }

        local_irq_restore(flags);
}

void local_flush_tlb_mm(struct mm_struct *mm)
{
        unsigned long flags;
        unsigned int cpu = smp_processor_id();

        if (cpu_context(cpu, mm) == NO_CONTEXT)
                return;

        local_irq_save(flags);

        cpu_context(cpu, mm) = NO_CONTEXT;
        if (mm == current->mm)
                activate_context(mm, cpu);

        local_irq_restore(flags);
}

void local_flush_tlb_all(void)
{
        /* Invalidate all, including shared pages, excluding fixed TLBs */
        unsigned long flags, tlb;

        local_irq_save(flags);

        /* Flush each ITLB entry */
        for_each_itlb_entry(tlb)
                __flush_tlb_slot(tlb);

        /* Flush each DTLB entry */
        for_each_dtlb_entry(tlb)
                __flush_tlb_slot(tlb);

        local_irq_restore(flags);
}

void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
        /* FIXME: Optimize this later.. */
        flush_tlb_all();
}