| Mikael Starvik | 51533b6 | 2005-07-27 11:44:44 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2003 Axis Communications AB |
| 3 | * |
| 4 | * Authors: Mikael Starvik (starvik@axis.com) |
| 5 | * |
| 6 | * Code for the fault low-level handling routines. |
| 7 | * |
| 8 | */ |
| 9 | |
| 10 | #include <asm/page.h> |
| 11 | #include <asm/pgtable.h> |
| 12 | |
| 13 | ; Save all register. Must save in same order as struct pt_regs. |
| 14 | .macro SAVE_ALL |
| 15 | subq 12, $sp |
| 16 | move $erp, [$sp] |
| 17 | subq 4, $sp |
| 18 | move $srp, [$sp] |
| 19 | subq 4, $sp |
| 20 | move $ccs, [$sp] |
| 21 | subq 4, $sp |
| 22 | move $spc, [$sp] |
| 23 | subq 4, $sp |
| 24 | move $mof, [$sp] |
| 25 | subq 4, $sp |
| 26 | move $srs, [$sp] |
| 27 | subq 4, $sp |
| 28 | move.d $acr, [$sp] |
| 29 | subq 14*4, $sp |
| 30 | movem $r13, [$sp] |
| 31 | subq 4, $sp |
| 32 | move.d $r10, [$sp] |
| 33 | .endm |
| 34 | |
| 35 | ; Bus fault handler. Extracts relevant information and calls mm subsystem |
| 36 | ; to handle the fault. |
| 37 | .macro MMU_BUS_FAULT_HANDLER handler, mmu, we, ex |
| 38 | .globl \handler |
| 39 | \handler: |
| 40 | SAVE_ALL |
| 41 | move \mmu, $srs ; Select MMU support register bank |
| 42 | move.d $sp, $r11 ; regs |
| 43 | moveq 1, $r12 ; protection fault |
| 44 | moveq \we, $r13 ; write exception? |
| 45 | orq \ex << 1, $r13 ; execute? |
| 46 | move $s3, $r10 ; rw_mm_cause |
| 47 | and.d ~8191, $r10 ; Get faulting page start address |
| 48 | |
| 49 | jsr do_page_fault |
| 50 | nop |
| 51 | ba ret_from_intr |
| 52 | nop |
| 53 | .endm |
| 54 | |
| 55 | ; Refill handler. Three cases may occur: |
| 56 | ; 1. PMD and PTE exists in mm subsystem but not in TLB |
| 57 | ; 2. PMD exists but not PTE |
| 58 | ; 3. PMD doesn't exist |
| 59 | ; The code below handles case 1 and calls the mm subsystem for case 2 and 3. |
| 60 | ; Do not touch this code without very good reasons and extensive testing. |
| 61 | ; Note that the code is optimized to minimize stalls (makes the code harder |
| 62 | ; to read). |
| 63 | ; |
| 64 | ; Each page is 8 KB. Each PMD holds 8192/4 PTEs (each PTE is 4 bytes) so each |
| 65 | ; PMD holds 16 MB of virtual memory. |
| 66 | ; Bits 0-12 : Offset within a page |
| 67 | ; Bits 13-23 : PTE offset within a PMD |
| 68 | ; Bits 24-31 : PMD offset within the PGD |
| 69 | |
| 70 | .macro MMU_REFILL_HANDLER handler, mmu |
| 71 | .globl \handler |
| 72 | \handler: |
| 73 | subq 4, $sp |
| 74 | ; (The pipeline stalls for one cycle; $sp used as address in the next cycle.) |
| 75 | move $srs, [$sp] |
| 76 | subq 4, $sp |
| 77 | move \mmu, $srs ; Select MMU support register bank |
| 78 | move.d $acr, [$sp] |
| 79 | subq 4, $sp |
| 80 | move.d $r0, [$sp] |
| 81 | #ifdef CONFIG_SMP |
| 82 | move $s7, $acr ; PGD |
| 83 | #else |
| 84 | move.d per_cpu__current_pgd, $acr ; PGD |
| 85 | #endif |
| 86 | ; Look up PMD in PGD |
| 87 | move $s3, $r0 ; rw_mm_cause |
| 88 | lsrq 24, $r0 ; Get PMD index into PGD (bit 24-31) |
| 89 | move.d [$acr], $acr ; PGD for the current process |
| 90 | addi $r0.d, $acr, $acr |
| 91 | move $s3, $r0 ; rw_mm_cause |
| 92 | move.d [$acr], $acr ; Get PMD |
| 93 | beq 1f |
| 94 | ; Look up PTE in PMD |
| 95 | lsrq PAGE_SHIFT, $r0 |
| 96 | and.w PAGE_MASK, $acr ; Remove PMD flags |
| 97 | and.d 0x7ff, $r0 ; Get PTE index into PMD (bit 13-23) |
| 98 | addi $r0.d, $acr, $acr |
| 99 | move.d [$acr], $acr ; Get PTE |
| 100 | beq 2f |
| 101 | move.d [$sp+], $r0 ; Pop r0 in delayslot |
| 102 | ; Store in TLB |
| 103 | move $acr, $s5 |
| 104 | ; Return |
| 105 | move.d [$sp+], $acr |
| 106 | move [$sp], $srs |
| 107 | addq 4, $sp |
| 108 | rete |
| 109 | rfe |
| 110 | 1: ; PMD missing, let the mm subsystem fix it up. |
| 111 | move.d [$sp+], $r0 ; Pop r0 |
| 112 | 2: ; PTE missing, let the mm subsystem fix it up. |
| 113 | move.d [$sp+], $acr |
| 114 | move [$sp], $srs |
| 115 | addq 4, $sp |
| 116 | SAVE_ALL |
| 117 | move \mmu, $srs |
| 118 | move.d $sp, $r11 ; regs |
| 119 | clear.d $r12 ; Not a protection fault |
| 120 | move.w PAGE_MASK, $acr |
| 121 | move $s3, $r10 ; rw_mm_cause |
| 122 | btstq 9, $r10 ; Check if write access |
| 123 | smi $r13 |
| 124 | and.w PAGE_MASK, $r10 ; Get VPN (virtual address) |
| 125 | jsr do_page_fault |
| 126 | and.w $acr, $r10 |
| 127 | ; Return |
| 128 | ba ret_from_intr |
| 129 | nop |
| 130 | .endm |
| 131 | |
| 132 | ; This is the MMU bus fault handlers. |
| 133 | |
| 134 | MMU_REFILL_HANDLER i_mmu_refill, 1 |
| 135 | MMU_BUS_FAULT_HANDLER i_mmu_invalid, 1, 0, 0 |
| 136 | MMU_BUS_FAULT_HANDLER i_mmu_access, 1, 0, 0 |
| 137 | MMU_BUS_FAULT_HANDLER i_mmu_execute, 1, 0, 1 |
| 138 | MMU_REFILL_HANDLER d_mmu_refill, 2 |
| 139 | MMU_BUS_FAULT_HANDLER d_mmu_invalid, 2, 0, 0 |
| 140 | MMU_BUS_FAULT_HANDLER d_mmu_access, 2, 0, 0 |
| 141 | MMU_BUS_FAULT_HANDLER d_mmu_write, 2, 1, 0 |