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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
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 */
40 #define PACA_EXGDBELL PACA_EXGEN
42 /* We are out of SPRGs so we save some things in the PACA. The normal
43 * exception frame is smaller than the CRIT or MC one though
44 */
45 #define EX_R1 (0 * 8)
46 #define EX_CR (1 * 8)
47 #define EX_R10 (2 * 8)
48 #define EX_R11 (3 * 8)
49 #define EX_R14 (4 * 8)
50 #define EX_R15 (5 * 8)
52 /*
53 * The TLB miss exception uses different slots.
54 *
55 * The bolted variant uses only the first six fields,
56 * which in combination with pgd and kernel_pgd fits in
57 * one 64-byte cache line.
58 */
60 #define EX_TLB_R10 ( 0 * 8)
61 #define EX_TLB_R11 ( 1 * 8)
62 #define EX_TLB_R14 ( 2 * 8)
63 #define EX_TLB_R15 ( 3 * 8)
64 #define EX_TLB_R16 ( 4 * 8)
65 #define EX_TLB_CR ( 5 * 8)
66 #define EX_TLB_R12 ( 6 * 8)
67 #define EX_TLB_R13 ( 7 * 8)
70 #define EX_TLB_SRR0 (10 * 8)
71 #define EX_TLB_SRR1 (11 * 8)
72 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS
73 #define EX_TLB_R8 (12 * 8)
74 #define EX_TLB_R9 (13 * 8)
75 #define EX_TLB_LR (14 * 8)
76 #define EX_TLB_SIZE (15 * 8)
77 #else
78 #define EX_TLB_SIZE (12 * 8)
79 #endif
81 #define START_EXCEPTION(label) \
82 .globl exc_##label##_book3e; \
83 exc_##label##_book3e:
85 /* TLB miss exception prolog
86 *
87 * This prolog handles re-entrancy (up to 3 levels supported in the PACA
88 * though we currently don't test for overflow). It provides you with a
89 * re-entrancy safe working space of r10...r16 and CR with r12 being used
90 * as the exception area pointer in the PACA for that level of re-entrancy
91 * and r13 containing the PACA pointer.
92 *
93 * SRR0 and SRR1 are saved, but DEAR and ESR are not, since they don't apply
94 * as-is for instruction exceptions. It's up to the actual exception code
95 * to save them as well if required.
96 */
97 #define TLB_MISS_PROLOG \
98 mtspr SPRN_SPRG_TLB_SCRATCH,r12; \
99 mfspr r12,SPRN_SPRG_TLB_EXFRAME; \
100 std r10,EX_TLB_R10(r12); \
101 mfcr r10; \
102 std r11,EX_TLB_R11(r12); \
103 mfspr r11,SPRN_SPRG_TLB_SCRATCH; \
104 std r13,EX_TLB_R13(r12); \
105 mfspr r13,SPRN_SPRG_PACA; \
106 std r14,EX_TLB_R14(r12); \
107 addi r14,r12,EX_TLB_SIZE; \
108 std r15,EX_TLB_R15(r12); \
109 mfspr r15,SPRN_SRR1; \
110 std r16,EX_TLB_R16(r12); \
111 mfspr r16,SPRN_SRR0; \
112 std r10,EX_TLB_CR(r12); \
113 std r11,EX_TLB_R12(r12); \
114 mtspr SPRN_SPRG_TLB_EXFRAME,r14; \
115 std r15,EX_TLB_SRR1(r12); \
116 std r16,EX_TLB_SRR0(r12); \
117 TLB_MISS_PROLOG_STATS
119 /* And these are the matching epilogs that restores things
120 *
121 * There are 3 epilogs:
122 *
123 * - SUCCESS : Unwinds one level
124 * - ERROR : restore from level 0 and reset
125 * - ERROR_SPECIAL : restore from current level and reset
126 *
127 * Normal errors use ERROR, that is, they restore the initial fault context
128 * and trigger a fault. However, there is a special case for linear mapping
129 * errors. Those should basically never happen, but if they do happen, we
130 * want the error to point out the context that did that linear mapping
131 * fault, not the initial level 0 (basically, we got a bogus PGF or something
132 * like that). For userland errors on the linear mapping, there is no
133 * difference since those are always level 0 anyway
134 */
136 #define TLB_MISS_RESTORE(freg) \
137 ld r14,EX_TLB_CR(r12); \
138 ld r10,EX_TLB_R10(r12); \
139 ld r15,EX_TLB_SRR0(r12); \
140 ld r16,EX_TLB_SRR1(r12); \
141 mtspr SPRN_SPRG_TLB_EXFRAME,freg; \
142 ld r11,EX_TLB_R11(r12); \
143 mtcr r14; \
144 ld r13,EX_TLB_R13(r12); \
145 ld r14,EX_TLB_R14(r12); \
146 mtspr SPRN_SRR0,r15; \
147 ld r15,EX_TLB_R15(r12); \
148 mtspr SPRN_SRR1,r16; \
149 TLB_MISS_RESTORE_STATS \
150 ld r16,EX_TLB_R16(r12); \
151 ld r12,EX_TLB_R12(r12); \
153 #define TLB_MISS_EPILOG_SUCCESS \
154 TLB_MISS_RESTORE(r12)
156 #define TLB_MISS_EPILOG_ERROR \
157 addi r12,r13,PACA_EXTLB; \
158 TLB_MISS_RESTORE(r12)
160 #define TLB_MISS_EPILOG_ERROR_SPECIAL \
161 addi r11,r13,PACA_EXTLB; \
162 TLB_MISS_RESTORE(r11)
164 #ifdef CONFIG_BOOK3E_MMU_TLB_STATS
165 #define TLB_MISS_PROLOG_STATS \
166 mflr r10; \
167 std r8,EX_TLB_R8(r12); \
168 std r9,EX_TLB_R9(r12); \
169 std r10,EX_TLB_LR(r12);
170 #define TLB_MISS_RESTORE_STATS \
171 ld r16,EX_TLB_LR(r12); \
172 ld r9,EX_TLB_R9(r12); \
173 ld r8,EX_TLB_R8(r12); \
174 mtlr r16;
175 #define TLB_MISS_STATS_D(name) \
176 addi r9,r13,MMSTAT_DSTATS+name; \
177 bl tlb_stat_inc;
178 #define TLB_MISS_STATS_I(name) \
179 addi r9,r13,MMSTAT_ISTATS+name; \
180 bl tlb_stat_inc;
181 #define TLB_MISS_STATS_X(name) \
182 ld r8,PACA_EXTLB+EX_TLB_ESR(r13); \
183 cmpdi cr2,r8,-1; \
184 beq cr2,61f; \
185 addi r9,r13,MMSTAT_DSTATS+name; \
186 b 62f; \
187 61: addi r9,r13,MMSTAT_ISTATS+name; \
188 62: bl tlb_stat_inc;
189 #define TLB_MISS_STATS_SAVE_INFO \
191 #define TLB_MISS_STATS_SAVE_INFO_BOLTED \
193 #else
194 #define TLB_MISS_PROLOG_STATS
195 #define TLB_MISS_RESTORE_STATS
196 #define TLB_MISS_PROLOG_STATS_BOLTED
197 #define TLB_MISS_RESTORE_STATS_BOLTED
198 #define TLB_MISS_STATS_D(name)
199 #define TLB_MISS_STATS_I(name)
200 #define TLB_MISS_STATS_X(name)
201 #define TLB_MISS_STATS_Y(name)
202 #define TLB_MISS_STATS_SAVE_INFO
203 #define TLB_MISS_STATS_SAVE_INFO_BOLTED
204 #endif
206 #define SET_IVOR(vector_number, vector_offset) \
207 li r3,vector_offset@l; \
208 ori r3,r3,interrupt_base_book3e@l; \
209 mtspr SPRN_IVOR##vector_number,r3;