arch/powerpc/include/asm/exception-64e.h

   1 /*
   2  *  Definitions for use by exception code on Book3-E
   3  *
   4  *  Copyright (C) 2008 Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  */
  11 #ifndef _ASM_POWERPC_EXCEPTION_64E_H
  12 #define _ASM_POWERPC_EXCEPTION_64E_H
  13
  14 /*
  15  * SPRGs usage an other considerations...
  16  *
  17  * Since TLB miss and other standard exceptions can be interrupted by
  18  * critical exceptions which can themselves be interrupted by machine
  19  * checks, and since the two later can themselves cause a TLB miss when
  20  * hitting the linear mapping for the kernel stacks, we need to be a bit
  21  * creative on how we use SPRGs.
  22  *
  23  * The base idea is that we have one SRPG reserved for critical and one
  24  * for machine check interrupts. Those are used to save a GPR that can
  25  * then be used to get the PACA, and store as much context as we need
  26  * to save in there. That includes saving the SPRGs used by the TLB miss
  27  * handler for linear mapping misses and the associated SRR0/1 due to
  28  * the above re-entrancy issue.
  29  *
  30  * So here's the current usage pattern. It's done regardless of which
  31  * SPRGs are user-readable though, thus we might have to change some of
  32  * this later. In order to do that more easily, we use special constants
  33  * for naming them
  34  *
  35  * WARNING: Some of these SPRGs are user readable. We need to do something
  36  * about it as some point by making sure they can't be used to leak kernel
  37  * critical data
  38  */
  39
  40
  41 /* We are out of SPRGs so we save some things in the PACA. The normal
  42  * exception frame is smaller than the CRIT or MC one though
  43  */
  44 #define EX_R1           (0 * 8)
  45 #define EX_CR           (1 * 8)
  46 #define EX_R10          (2 * 8)
  47 #define EX_R11          (3 * 8)
  48 #define EX_R14          (4 * 8)
  49 #define EX_R15          (5 * 8)
  50
  51 /*
  52  * The TLB miss exception uses different slots.
  53  *
  54  * The bolted variant uses only the first six fields,
  55  * which in combination with pgd and kernel_pgd fits in
  56  * one 64-byte cache line.
  57  */
  58
  59 #define EX_TLB_R10      ( 0 * 8)
  60 #define EX_TLB_R11      ( 1 * 8)
  61 #define EX_TLB_R14      ( 2 * 8)
  62 #define EX_TLB_R15      ( 3 * 8)
  63 #define EX_TLB_R16      ( 4 * 8)
  64 #define EX_TLB_CR       ( 5 * 8)
  65 #define EX_TLB_R12      ( 6 * 8)
  66 #define EX_TLB_R13      ( 7 * 8)
  67 #define EX_TLB_DEAR     ( 8 * 8) /* Level 0 and 2 only */
  68 #define EX_TLB_ESR      ( 9 * 8) /* Level 0 and 2 only */
  69 #define EX_TLB_SRR0     (10 * 8)
  70 #define EX_TLB_SRR1     (11 * 8)
  71 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS
  72 #define EX_TLB_R8       (12 * 8)
  73 #define EX_TLB_R9       (13 * 8)
  74 #define EX_TLB_LR       (14 * 8)
  75 #define EX_TLB_SIZE     (15 * 8)
  76 #else
  77 #define EX_TLB_SIZE     (12 * 8)
  78 #endif
  79
  80 #define START_EXCEPTION(label)                                          \
  81         .globl exc_##label##_book3e;                                    \
  82 exc_##label##_book3e:
  83
  84 /* TLB miss exception prolog
  85  *
  86  * This prolog handles re-entrancy (up to 3 levels supported in the PACA
  87  * though we currently don't test for overflow). It provides you with a
  88  * re-entrancy safe working space of r10...r16 and CR with r12 being used
  89  * as the exception area pointer in the PACA for that level of re-entrancy
  90  * and r13 containing the PACA pointer.
  91  *
  92  * SRR0 and SRR1 are saved, but DEAR and ESR are not, since they don't apply
  93  * as-is for instruction exceptions. It's up to the actual exception code
  94  * to save them as well if required.
  95  */
  96 #define TLB_MISS_PROLOG                                                     \
  97         mtspr   SPRN_SPRG_TLB_SCRATCH,r12;                                  \
  98         mfspr   r12,SPRN_SPRG_TLB_EXFRAME;                                  \
  99         std     r10,EX_TLB_R10(r12);                                        \
 100         mfcr    r10;                                                        \
 101         std     r11,EX_TLB_R11(r12);                                        \
 102         mfspr   r11,SPRN_SPRG_TLB_SCRATCH;                                  \
 103         std     r13,EX_TLB_R13(r12);                                        \
 104         mfspr   r13,SPRN_SPRG_PACA;                                         \
 105         std     r14,EX_TLB_R14(r12);                                        \
 106         addi    r14,r12,EX_TLB_SIZE;                                        \
 107         std     r15,EX_TLB_R15(r12);                                        \
 108         mfspr   r15,SPRN_SRR1;                                              \
 109         std     r16,EX_TLB_R16(r12);                                        \
 110         mfspr   r16,SPRN_SRR0;                                              \
 111         std     r10,EX_TLB_CR(r12);                                         \
 112         std     r11,EX_TLB_R12(r12);                                        \
 113         mtspr   SPRN_SPRG_TLB_EXFRAME,r14;                                  \
 114         std     r15,EX_TLB_SRR1(r12);                                       \
 115         std     r16,EX_TLB_SRR0(r12);                                       \
 116         TLB_MISS_PROLOG_STATS
 117
 118 /* And these are the matching epilogs that restores things
 119  *
 120  * There are 3 epilogs:
 121  *
 122  * - SUCCESS       : Unwinds one level
 123  * - ERROR         : restore from level 0 and reset
 124  * - ERROR_SPECIAL : restore from current level and reset
 125  *
 126  * Normal errors use ERROR, that is, they restore the initial fault context
 127  * and trigger a fault. However, there is a special case for linear mapping
 128  * errors. Those should basically never happen, but if they do happen, we
 129  * want the error to point out the context that did that linear mapping
 130  * fault, not the initial level 0 (basically, we got a bogus PGF or something
 131  * like that). For userland errors on the linear mapping, there is no
 132  * difference since those are always level 0 anyway
 133  */
 134
 135 #define TLB_MISS_RESTORE(freg)                                              \
 136         ld      r14,EX_TLB_CR(r12);                                         \
 137         ld      r10,EX_TLB_R10(r12);                                        \
 138         ld      r15,EX_TLB_SRR0(r12);                                       \
 139         ld      r16,EX_TLB_SRR1(r12);                                       \
 140         mtspr   SPRN_SPRG_TLB_EXFRAME,freg;                                 \
 141         ld      r11,EX_TLB_R11(r12);                                        \
 142         mtcr    r14;                                                        \
 143         ld      r13,EX_TLB_R13(r12);                                        \
 144         ld      r14,EX_TLB_R14(r12);                                        \
 145         mtspr   SPRN_SRR0,r15;                                              \
 146         ld      r15,EX_TLB_R15(r12);                                        \
 147         mtspr   SPRN_SRR1,r16;                                              \
 148         TLB_MISS_RESTORE_STATS                                              \
 149         ld      r16,EX_TLB_R16(r12);                                        \
 150         ld      r12,EX_TLB_R12(r12);                                        \
 151
 152 #define TLB_MISS_EPILOG_SUCCESS                                             \
 153         TLB_MISS_RESTORE(r12)
 154
 155 #define TLB_MISS_EPILOG_ERROR                                               \
 156         addi    r12,r13,PACA_EXTLB;                                         \
 157         TLB_MISS_RESTORE(r12)
 158
 159 #define TLB_MISS_EPILOG_ERROR_SPECIAL                                       \
 160         addi    r11,r13,PACA_EXTLB;                                         \
 161         TLB_MISS_RESTORE(r11)
 162
 163 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS
 164 #define TLB_MISS_PROLOG_STATS                                               \
 165         mflr    r10;                                                        \
 166         std     r8,EX_TLB_R8(r12);                                          \
 167         std     r9,EX_TLB_R9(r12);                                          \
 168         std     r10,EX_TLB_LR(r12);
 169 #define TLB_MISS_RESTORE_STATS                                              \
 170         ld      r16,EX_TLB_LR(r12);                                         \
 171         ld      r9,EX_TLB_R9(r12);                                          \
 172         ld      r8,EX_TLB_R8(r12);                                          \
 173         mtlr    r16;
 174 #define TLB_MISS_PROLOG_STATS_BOLTED                                                \
 175         mflr    r10;                                                        \
 176         std     r8,PACA_EXTLB+EX_TLB_R8(r13);                               \
 177         std     r9,PACA_EXTLB+EX_TLB_R9(r13);                               \
 178         std     r10,PACA_EXTLB+EX_TLB_LR(r13);
 179 #define TLB_MISS_RESTORE_STATS_BOLTED                                               \
 180         ld      r16,PACA_EXTLB+EX_TLB_LR(r13);                              \
 181         ld      r9,PACA_EXTLB+EX_TLB_R9(r13);                               \
 182         ld      r8,PACA_EXTLB+EX_TLB_R8(r13);                               \
 183         mtlr    r16;
 184 #define TLB_MISS_STATS_D(name)                                              \
 185         addi    r9,r13,MMSTAT_DSTATS+name;                                  \
 186         bl      .tlb_stat_inc;
 187 #define TLB_MISS_STATS_I(name)                                              \
 188         addi    r9,r13,MMSTAT_ISTATS+name;                                  \
 189         bl      .tlb_stat_inc;
 190 #define TLB_MISS_STATS_X(name)                                              \
 191         ld      r8,PACA_EXTLB+EX_TLB_ESR(r13);                              \
 192         cmpdi   cr2,r8,-1;                                                  \
 193         beq     cr2,61f;                                                    \
 194         addi    r9,r13,MMSTAT_DSTATS+name;                                  \
 195         b       62f;                                                        \
 196 61:     addi    r9,r13,MMSTAT_ISTATS+name;                                  \
 197 62:     bl      .tlb_stat_inc;
 198 #define TLB_MISS_STATS_SAVE_INFO                                            \
 199         std     r14,EX_TLB_ESR(r12);    /* save ESR */
 200 #define TLB_MISS_STATS_SAVE_INFO_BOLTED                                     \
 201         std     r14,PACA_EXTLB+EX_TLB_ESR(r13); /* save ESR */
 202 #else
 203 #define TLB_MISS_PROLOG_STATS
 204 #define TLB_MISS_RESTORE_STATS
 205 #define TLB_MISS_PROLOG_STATS_BOLTED
 206 #define TLB_MISS_RESTORE_STATS_BOLTED
 207 #define TLB_MISS_STATS_D(name)
 208 #define TLB_MISS_STATS_I(name)
 209 #define TLB_MISS_STATS_X(name)
 210 #define TLB_MISS_STATS_Y(name)
 211 #define TLB_MISS_STATS_SAVE_INFO
 212 #define TLB_MISS_STATS_SAVE_INFO_BOLTED
 213 #endif
 214
 215 #define SET_IVOR(vector_number, vector_offset)  \
 216         li      r3,vector_offset@l;             \
 217         ori     r3,r3,interrupt_base_book3e@l;  \
 218         mtspr   SPRN_IVOR##vector_number,r3;
 219
 220 #endif /* _ASM_POWERPC_EXCEPTION_64E_H */
 221