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
handle_mmu_bus_fault(struct pt_regs * regs)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 }
96