1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Definitions for use by exception code on Book3-E 4 * 5 * Copyright (C) 2008 Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp. 6 */ 7 #ifndef _ASM_POWERPC_EXCEPTION_64E_H 8 #define _ASM_POWERPC_EXCEPTION_64E_H 9 10 /* 11 * SPRGs usage an other considerations... 12 * 13 * Since TLB miss and other standard exceptions can be interrupted by 14 * critical exceptions which can themselves be interrupted by machine 15 * checks, and since the two later can themselves cause a TLB miss when 16 * hitting the linear mapping for the kernel stacks, we need to be a bit 17 * creative on how we use SPRGs. 18 * 19 * The base idea is that we have one SRPG reserved for critical and one 20 * for machine check interrupts. Those are used to save a GPR that can 21 * then be used to get the PACA, and store as much context as we need 22 * to save in there. That includes saving the SPRGs used by the TLB miss 23 * handler for linear mapping misses and the associated SRR0/1 due to 24 * the above re-entrancy issue. 25 * 26 * So here's the current usage pattern. It's done regardless of which 27 * SPRGs are user-readable though, thus we might have to change some of 28 * this later. In order to do that more easily, we use special constants 29 * for naming them 30 * 31 * WARNING: Some of these SPRGs are user readable. We need to do something 32 * about it as some point by making sure they can't be used to leak kernel 33 * critical data 34 */ 35 36 #define PACA_EXGDBELL PACA_EXGEN 37 38 /* We are out of SPRGs so we save some things in the PACA. The normal 39 * exception frame is smaller than the CRIT or MC one though 40 */ 41 #define EX_R1 (0 * 8) 42 #define EX_CR (1 * 8) 43 #define EX_R10 (2 * 8) 44 #define EX_R11 (3 * 8) 45 #define EX_R14 (4 * 8) 46 #define EX_R15 (5 * 8) 47 48 /* 49 * The TLB miss exception uses different slots. 50 * 51 * The bolted variant uses only the first six fields, 52 * which in combination with pgd and kernel_pgd fits in 53 * one 64-byte cache line. 54 */ 55 56 #define EX_TLB_R10 ( 0 * 8) 57 #define EX_TLB_R11 ( 1 * 8) 58 #define EX_TLB_R14 ( 2 * 8) 59 #define EX_TLB_R15 ( 3 * 8) 60 #define EX_TLB_R16 ( 4 * 8) 61 #define EX_TLB_CR ( 5 * 8) 62 #define EX_TLB_R12 ( 6 * 8) 63 #define EX_TLB_R13 ( 7 * 8) 64 #define EX_TLB_DEAR ( 8 * 8) /* Level 0 and 2 only */ 65 #define EX_TLB_ESR ( 9 * 8) /* Level 0 and 2 only */ 66 #define EX_TLB_SRR0 (10 * 8) 67 #define EX_TLB_SRR1 (11 * 8) 68 #define EX_TLB_R7 (12 * 8) 69 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS 70 #define EX_TLB_R8 (13 * 8) 71 #define EX_TLB_R9 (14 * 8) 72 #define EX_TLB_LR (15 * 8) 73 #define EX_TLB_SIZE (16 * 8) 74 #else 75 #define EX_TLB_SIZE (13 * 8) 76 #endif 77 78 #define START_EXCEPTION(label) \ 79 .globl exc_##label##_book3e; \ 80 exc_##label##_book3e: 81 82 /* TLB miss exception prolog 83 * 84 * This prolog handles re-entrancy (up to 3 levels supported in the PACA 85 * though we currently don't test for overflow). It provides you with a 86 * re-entrancy safe working space of r10...r16 and CR with r12 being used 87 * as the exception area pointer in the PACA for that level of re-entrancy 88 * and r13 containing the PACA pointer. 89 * 90 * SRR0 and SRR1 are saved, but DEAR and ESR are not, since they don't apply 91 * as-is for instruction exceptions. It's up to the actual exception code 92 * to save them as well if required. 93 */ 94 #define TLB_MISS_PROLOG \ 95 mtspr SPRN_SPRG_TLB_SCRATCH,r12; \ 96 mfspr r12,SPRN_SPRG_TLB_EXFRAME; \ 97 std r10,EX_TLB_R10(r12); \ 98 mfcr r10; \ 99 std r11,EX_TLB_R11(r12); \ 100 mfspr r11,SPRN_SPRG_TLB_SCRATCH; \ 101 std r13,EX_TLB_R13(r12); \ 102 mfspr r13,SPRN_SPRG_PACA; \ 103 std r14,EX_TLB_R14(r12); \ 104 addi r14,r12,EX_TLB_SIZE; \ 105 std r15,EX_TLB_R15(r12); \ 106 mfspr r15,SPRN_SRR1; \ 107 std r16,EX_TLB_R16(r12); \ 108 mfspr r16,SPRN_SRR0; \ 109 std r10,EX_TLB_CR(r12); \ 110 std r11,EX_TLB_R12(r12); \ 111 mtspr SPRN_SPRG_TLB_EXFRAME,r14; \ 112 std r15,EX_TLB_SRR1(r12); \ 113 std r16,EX_TLB_SRR0(r12); \ 114 TLB_MISS_PROLOG_STATS 115 116 /* And these are the matching epilogs that restores things 117 * 118 * There are 3 epilogs: 119 * 120 * - SUCCESS : Unwinds one level 121 * - ERROR : restore from level 0 and reset 122 * - ERROR_SPECIAL : restore from current level and reset 123 * 124 * Normal errors use ERROR, that is, they restore the initial fault context 125 * and trigger a fault. However, there is a special case for linear mapping 126 * errors. Those should basically never happen, but if they do happen, we 127 * want the error to point out the context that did that linear mapping 128 * fault, not the initial level 0 (basically, we got a bogus PGF or something 129 * like that). For userland errors on the linear mapping, there is no 130 * difference since those are always level 0 anyway 131 */ 132 133 #define TLB_MISS_RESTORE(freg) \ 134 ld r14,EX_TLB_CR(r12); \ 135 ld r10,EX_TLB_R10(r12); \ 136 ld r15,EX_TLB_SRR0(r12); \ 137 ld r16,EX_TLB_SRR1(r12); \ 138 mtspr SPRN_SPRG_TLB_EXFRAME,freg; \ 139 ld r11,EX_TLB_R11(r12); \ 140 mtcr r14; \ 141 ld r13,EX_TLB_R13(r12); \ 142 ld r14,EX_TLB_R14(r12); \ 143 mtspr SPRN_SRR0,r15; \ 144 ld r15,EX_TLB_R15(r12); \ 145 mtspr SPRN_SRR1,r16; \ 146 TLB_MISS_RESTORE_STATS \ 147 ld r16,EX_TLB_R16(r12); \ 148 ld r12,EX_TLB_R12(r12); \ 149 150 #define TLB_MISS_EPILOG_SUCCESS \ 151 TLB_MISS_RESTORE(r12) 152 153 #define TLB_MISS_EPILOG_ERROR \ 154 addi r12,r13,PACA_EXTLB; \ 155 TLB_MISS_RESTORE(r12) 156 157 #define TLB_MISS_EPILOG_ERROR_SPECIAL \ 158 addi r11,r13,PACA_EXTLB; \ 159 TLB_MISS_RESTORE(r11) 160 161 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS 162 #define TLB_MISS_PROLOG_STATS \ 163 mflr r10; \ 164 std r8,EX_TLB_R8(r12); \ 165 std r9,EX_TLB_R9(r12); \ 166 std r10,EX_TLB_LR(r12); 167 #define TLB_MISS_RESTORE_STATS \ 168 ld r16,EX_TLB_LR(r12); \ 169 ld r9,EX_TLB_R9(r12); \ 170 ld r8,EX_TLB_R8(r12); \ 171 mtlr r16; 172 #define TLB_MISS_STATS_D(name) \ 173 addi r9,r13,MMSTAT_DSTATS+name; \ 174 bl tlb_stat_inc; 175 #define TLB_MISS_STATS_I(name) \ 176 addi r9,r13,MMSTAT_ISTATS+name; \ 177 bl tlb_stat_inc; 178 #define TLB_MISS_STATS_X(name) \ 179 ld r8,PACA_EXTLB+EX_TLB_ESR(r13); \ 180 cmpdi cr2,r8,-1; \ 181 beq cr2,61f; \ 182 addi r9,r13,MMSTAT_DSTATS+name; \ 183 b 62f; \ 184 61: addi r9,r13,MMSTAT_ISTATS+name; \ 185 62: bl tlb_stat_inc; 186 #define TLB_MISS_STATS_SAVE_INFO \ 187 std r14,EX_TLB_ESR(r12); /* save ESR */ 188 #define TLB_MISS_STATS_SAVE_INFO_BOLTED \ 189 std r14,PACA_EXTLB+EX_TLB_ESR(r13); /* save ESR */ 190 #else 191 #define TLB_MISS_PROLOG_STATS 192 #define TLB_MISS_RESTORE_STATS 193 #define TLB_MISS_PROLOG_STATS_BOLTED 194 #define TLB_MISS_RESTORE_STATS_BOLTED 195 #define TLB_MISS_STATS_D(name) 196 #define TLB_MISS_STATS_I(name) 197 #define TLB_MISS_STATS_X(name) 198 #define TLB_MISS_STATS_Y(name) 199 #define TLB_MISS_STATS_SAVE_INFO 200 #define TLB_MISS_STATS_SAVE_INFO_BOLTED 201 #endif 202 203 #define SET_IVOR(vector_number, vector_offset) \ 204 LOAD_REG_ADDR(r3,interrupt_base_book3e);\ 205 ori r3,r3,vector_offset@l; \ 206 mtspr SPRN_IVOR##vector_number,r3; 207 208 #define RFI_TO_KERNEL \ 209 rfi 210 211 #define RFI_TO_USER \ 212 rfi 213 214 #endif /* _ASM_POWERPC_EXCEPTION_64E_H */ 215 216