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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/cris/arch-v10/mm/fault.c
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/*

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 *  linux/arch/cris/mm/fault.c

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 *

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 *  Low level bus fault handler

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 *

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 *

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 *  Copyright (C) 2000-2007  Axis Communications AB

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 *

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 *  Authors:  Bjorn Wesen

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 *

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 */

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#include <linux/mm.h>

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#include <asm/uaccess.h>

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#include <asm/pgtable.h>

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#include <arch/svinto.h>

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#include <asm/mmu_context.h>

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/* debug of low-level TLB reload */

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#undef DEBUG

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#ifdef DEBUG

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#define D(x) x

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#else

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#define D(x)

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#endif

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extern const struct exception_table_entry

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	*search_exception_tables(unsigned long addr);

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asmlinkage void do_page_fault(unsigned long address, struct pt_regs *regs,

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                              int protection, int writeaccess);

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/* fast TLB-fill fault handler

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 * this is called from entry.S with interrupts disabled

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 */

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void

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handle_mmu_bus_fault(struct pt_regs *regs)

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{

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	int cause;

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	int select;

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#ifdef DEBUG

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	int index;

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	int page_id;

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	int acc, inv;

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#endif

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	pgd_t* pgd = (pgd_t*)per_cpu(current_pgd, smp_processor_id());

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	pmd_t *pmd;

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	pte_t pte;

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	int miss, we, writeac;

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	unsigned long address;

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	unsigned long flags;

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	cause = *R_MMU_CAUSE;

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	address = cause & PAGE_MASK; /* get faulting address */

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	select = *R_TLB_SELECT;

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#ifdef DEBUG

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	page_id = IO_EXTRACT(R_MMU_CAUSE,  page_id,   cause);

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	acc     = IO_EXTRACT(R_MMU_CAUSE,  acc_excp,  cause);

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	inv     = IO_EXTRACT(R_MMU_CAUSE,  inv_excp,  cause);

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	index   = IO_EXTRACT(R_TLB_SELECT, index,     select);

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#endif

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	miss    = IO_EXTRACT(R_MMU_CAUSE,  miss_excp, cause);

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	we      = IO_EXTRACT(R_MMU_CAUSE,  we_excp,   cause);

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	writeac = IO_EXTRACT(R_MMU_CAUSE,  wr_rd,     cause);

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	D(printk("bus_fault from IRP 0x%lx: addr 0x%lx, miss %d, inv %d, we %d, acc %d, dx %d pid %d\n",

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		 regs->irp, address, miss, inv, we, acc, index, page_id));

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	/* leave it to the MM system fault handler */

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	if (miss)

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		do_page_fault(address, regs, 0, writeac);

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        else

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		do_page_fault(address, regs, 1, we);

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        /* Reload TLB with new entry to avoid an extra miss exception.

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	 * do_page_fault may have flushed the TLB so we have to restore

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	 * the MMU registers.

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	 */

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	local_irq_save(flags);

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	pmd = (pmd_t *)(pgd + pgd_index(address));

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	if (pmd_none(*pmd))

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		goto exit;

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	pte = *pte_offset_kernel(pmd, address);

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	if (!pte_present(pte))

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		goto exit;

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	*R_TLB_SELECT = select;

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	*R_TLB_HI = cause;

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	*R_TLB_LO = pte_val(pte);

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exit:

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	local_irq_restore(flags);

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}

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