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

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/arch/cris/mm/fault.c
   4  *
   5  *  Low level bus fault handler
   6  *
   7  *
   8  *  Copyright (C) 2000-2007  Axis Communications AB
   9  *
  10  *  Authors:  Bjorn Wesen
  11  *
  12  */
  13
  14 #include <linux/mm.h>
  15 #include <linux/uaccess.h>
  16 #include <asm/pgtable.h>
  17 #include <arch/svinto.h>
  18 #include <asm/mmu_context.h>
  19
  20 /* debug of low-level TLB reload */
  21 #undef DEBUG
  22
  23 #ifdef DEBUG
  24 #define D(x) x
  25 #else
  26 #define D(x)
  27 #endif
  28
  29 extern const struct exception_table_entry
  30         *search_exception_tables(unsigned long addr);
  31
  32 asmlinkage void do_page_fault(unsigned long address, struct pt_regs *regs,
  33                               int protection, int writeaccess);
  34
  35 /* fast TLB-fill fault handler
  36  * this is called from entry.S with interrupts disabled
  37  */
  38
  39 void
  40 handle_mmu_bus_fault(struct pt_regs *regs)
  41 {
  42         int cause;
  43         int select;
  44 #ifdef DEBUG
  45         int index;
  46         int page_id;
  47         int acc, inv;
  48 #endif
  49         pgd_t* pgd = (pgd_t*)per_cpu(current_pgd, smp_processor_id());
  50         pmd_t *pmd;
  51         pte_t pte;
  52         int miss, we, writeac;
  53         unsigned long address;
  54         unsigned long flags;
  55
  56         cause = *R_MMU_CAUSE;
  57
  58         address = cause & PAGE_MASK; /* get faulting address */
  59         select = *R_TLB_SELECT;
  60
  61 #ifdef DEBUG
  62         page_id = IO_EXTRACT(R_MMU_CAUSE,  page_id,   cause);
  63         acc     = IO_EXTRACT(R_MMU_CAUSE,  acc_excp,  cause);
  64         inv     = IO_EXTRACT(R_MMU_CAUSE,  inv_excp,  cause);
  65         index   = IO_EXTRACT(R_TLB_SELECT, index,     select);
  66 #endif
  67         miss    = IO_EXTRACT(R_MMU_CAUSE,  miss_excp, cause);
  68         we      = IO_EXTRACT(R_MMU_CAUSE,  we_excp,   cause);
  69         writeac = IO_EXTRACT(R_MMU_CAUSE,  wr_rd,     cause);
  70
  71         D(printk("bus_fault from IRP 0x%lx: addr 0x%lx, miss %d, inv %d, we %d, acc %d, dx %d pid %d\n",
  72                  regs->irp, address, miss, inv, we, acc, index, page_id));
  73
  74         /* leave it to the MM system fault handler */
  75         if (miss)
  76                 do_page_fault(address, regs, 0, writeac);
  77         else
  78                 do_page_fault(address, regs, 1, we);
  79
  80         /* Reload TLB with new entry to avoid an extra miss exception.
  81          * do_page_fault may have flushed the TLB so we have to restore
  82          * the MMU registers.
  83          */
  84         local_irq_save(flags);
  85         pmd = (pmd_t *)(pgd + pgd_index(address));
  86         if (pmd_none(*pmd))
  87                 goto exit;
  88         pte = *pte_offset_kernel(pmd, address);
  89         if (!pte_present(pte))
  90                 goto exit;
  91         *R_TLB_SELECT = select;
  92         *R_TLB_HI = cause;
  93         *R_TLB_LO = pte_val(pte);
  94 exit:
  95         local_irq_restore(flags);
  96 }