arch/cris/arch-v10/mm/fault.c

   1 /*
   2  *  linux/arch/cris/mm/fault.c
   3  *
   4  *  Low level bus fault handler
   5  *
   6  *
   7  *  Copyright (C) 2000-2007  Axis Communications AB
   8  *
   9  *  Authors:  Bjorn Wesen
  10  *
  11  */
  12
  13 #include <linux/mm.h>
  14 #include <asm/uaccess.h>
  15 #include <asm/pgtable.h>
  16 #include <arch/svinto.h>
  17 #include <asm/mmu_context.h>
  18
  19 /* debug of low-level TLB reload */
  20 #undef DEBUG
  21
  22 #ifdef DEBUG
  23 #define D(x) x
  24 #else
  25 #define D(x)
  26 #endif
  27
  28 extern const struct exception_table_entry
  29         *search_exception_tables(unsigned long addr);
  30
  31 asmlinkage void do_page_fault(unsigned long address, struct pt_regs *regs,
  32                               int protection, int writeaccess);
  33
  34 /* fast TLB-fill fault handler
  35  * this is called from entry.S with interrupts disabled
  36  */
  37
  38 void
  39 handle_mmu_bus_fault(struct pt_regs *regs)
  40 {
  41         int cause;
  42         int select;
  43 #ifdef DEBUG
  44         int index;
  45         int page_id;
  46         int acc, inv;
  47 #endif
  48         pgd_t* pgd = (pgd_t*)per_cpu(current_pgd, smp_processor_id());
  49         pmd_t *pmd;
  50         pte_t pte;
  51         int miss, we, writeac;
  52         unsigned long address;
  53         unsigned long flags;
  54
  55         cause = *R_MMU_CAUSE;
  56
  57         address = cause & PAGE_MASK; /* get faulting address */
  58         select = *R_TLB_SELECT;
  59
  60 #ifdef DEBUG
  61         page_id = IO_EXTRACT(R_MMU_CAUSE,  page_id,   cause);
  62         acc     = IO_EXTRACT(R_MMU_CAUSE,  acc_excp,  cause);
  63         inv     = IO_EXTRACT(R_MMU_CAUSE,  inv_excp,  cause);
  64         index   = IO_EXTRACT(R_TLB_SELECT, index,     select);
  65 #endif
  66         miss    = IO_EXTRACT(R_MMU_CAUSE,  miss_excp, cause);
  67         we      = IO_EXTRACT(R_MMU_CAUSE,  we_excp,   cause);
  68         writeac = IO_EXTRACT(R_MMU_CAUSE,  wr_rd,     cause);
  69
  70         D(printk("bus_fault from IRP 0x%lx: addr 0x%lx, miss %d, inv %d, we %d, acc %d, dx %d pid %d\n",
  71                  regs->irp, address, miss, inv, we, acc, index, page_id));
  72
  73         /* leave it to the MM system fault handler */
  74         if (miss)
  75                 do_page_fault(address, regs, 0, writeac);
  76         else
  77                 do_page_fault(address, regs, 1, we);
  78
  79         /* Reload TLB with new entry to avoid an extra miss exception.
  80          * do_page_fault may have flushed the TLB so we have to restore
  81          * the MMU registers.
  82          */
  83         local_irq_save(flags);
  84         pmd = (pmd_t *)(pgd + pgd_index(address));
  85         if (pmd_none(*pmd))
  86                 goto exit;
  87         pte = *pte_offset_kernel(pmd, address);
  88         if (!pte_present(pte))
  89                 goto exit;
  90         *R_TLB_SELECT = select;
  91         *R_TLB_HI = cause;
  92         *R_TLB_LO = pte_val(pte);
  93 exit:
  94         local_irq_restore(flags);
  95 }