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tlbflush_64.c

/*
 * 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();
}

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