1/*
2 *  linux/arch/cris/mm/fault.c
3 *
4 *  Low level bus fault handler
5 *
6 *
7 *  Copyright (C) 2000, 2001  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 <asm/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
28extern const struct exception_table_entry
29	*search_exception_tables(unsigned long addr);
30
31asmlinkage 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
38void
39handle_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_save_flags(flags);
84	local_irq_disable();
85	pmd = (pmd_t *)(pgd + pgd_index(address));
86	if (pmd_none(*pmd))
87		return;
88	pte = *pte_offset_kernel(pmd, address);
89	if (!pte_present(pte))
90		return;
91	*R_TLB_SELECT = select;
92	*R_TLB_HI = cause;
93	*R_TLB_LO = pte_val(pte);
94	local_irq_restore(flags);
95}
96