--- /dev/null
+/*
+ * Definitions for use by exception code on Book3-E
+ *
+ * Copyright (C) 2008 Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#ifndef _ASM_POWERPC_EXCEPTION_64E_H
+#define _ASM_POWERPC_EXCEPTION_64E_H
+
+/*
+ * SPRGs usage an other considerations...
+ *
+ * Since TLB miss and other standard exceptions can be interrupted by
+ * critical exceptions which can themselves be interrupted by machine
+ * checks, and since the two later can themselves cause a TLB miss when
+ * hitting the linear mapping for the kernel stacks, we need to be a bit
+ * creative on how we use SPRGs.
+ *
+ * The base idea is that we have one SRPG reserved for critical and one
+ * for machine check interrupts. Those are used to save a GPR that can
+ * then be used to get the PACA, and store as much context as we need
+ * to save in there. That includes saving the SPRGs used by the TLB miss
+ * handler for linear mapping misses and the associated SRR0/1 due to
+ * the above re-entrancy issue.
+ *
+ * So here's the current usage pattern. It's done regardless of which
+ * SPRGs are user-readable though, thus we might have to change some of
+ * this later. In order to do that more easily, we use special constants
+ * for naming them
+ *
+ * WARNING: Some of these SPRGs are user readable. We need to do something
+ * about it as some point by making sure they can't be used to leak kernel
+ * critical data
+ */
+
+
+/* We are out of SPRGs so we save some things in the PACA. The normal
+ * exception frame is smaller than the CRIT or MC one though
+ */
+#define EX_R1 (0 * 8)
+#define EX_CR (1 * 8)
+#define EX_R10 (2 * 8)
+#define EX_R11 (3 * 8)
+#define EX_R14 (4 * 8)
+#define EX_R15 (5 * 8)
+
+/* The TLB miss exception uses different slots */
+
+#define EX_TLB_R10 ( 0 * 8)
+#define EX_TLB_R11 ( 1 * 8)
+#define EX_TLB_R12 ( 2 * 8)
+#define EX_TLB_R13 ( 3 * 8)
+#define EX_TLB_R14 ( 4 * 8)
+#define EX_TLB_R15 ( 5 * 8)
+#define EX_TLB_R16 ( 6 * 8)
+#define EX_TLB_CR ( 7 * 8)
+#define EX_TLB_DEAR ( 8 * 8) /* Level 0 and 2 only */
+#define EX_TLB_ESR ( 9 * 8) /* Level 0 and 2 only */
+#define EX_TLB_SRR0 (10 * 8)
+#define EX_TLB_SRR1 (11 * 8)
+#define EX_TLB_MMUCR0 (12 * 8) /* Level 0 */
+#define EX_TLB_MAS1 (12 * 8) /* Level 0 */
+#define EX_TLB_MAS2 (13 * 8) /* Level 0 */
+#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
+#define EX_TLB_R8 (14 * 8)
+#define EX_TLB_R9 (15 * 8)
+#define EX_TLB_LR (16 * 8)
+#define EX_TLB_SIZE (17 * 8)
+#else
+#define EX_TLB_SIZE (14 * 8)
+#endif
+
+#define START_EXCEPTION(label) \
+ .globl exc_##label##_book3e; \
+exc_##label##_book3e:
+
+/* TLB miss exception prolog
+ *
+ * This prolog handles re-entrancy (up to 3 levels supported in the PACA
+ * though we currently don't test for overflow). It provides you with a
+ * re-entrancy safe working space of r10...r16 and CR with r12 being used
+ * as the exception area pointer in the PACA for that level of re-entrancy
+ * and r13 containing the PACA pointer.
+ *
+ * SRR0 and SRR1 are saved, but DEAR and ESR are not, since they don't apply
+ * as-is for instruction exceptions. It's up to the actual exception code
+ * to save them as well if required.
+ */
+#define TLB_MISS_PROLOG \
+ mtspr SPRN_SPRG_TLB_SCRATCH,r12; \
+ mfspr r12,SPRN_SPRG_TLB_EXFRAME; \
+ std r10,EX_TLB_R10(r12); \
+ mfcr r10; \
+ std r11,EX_TLB_R11(r12); \
+ mfspr r11,SPRN_SPRG_TLB_SCRATCH; \
+ std r13,EX_TLB_R13(r12); \
+ mfspr r13,SPRN_SPRG_PACA; \
+ std r14,EX_TLB_R14(r12); \
+ addi r14,r12,EX_TLB_SIZE; \
+ std r15,EX_TLB_R15(r12); \
+ mfspr r15,SPRN_SRR1; \
+ std r16,EX_TLB_R16(r12); \
+ mfspr r16,SPRN_SRR0; \
+ std r10,EX_TLB_CR(r12); \
+ std r11,EX_TLB_R12(r12); \
+ mtspr SPRN_SPRG_TLB_EXFRAME,r14; \
+ std r15,EX_TLB_SRR1(r12); \
+ std r16,EX_TLB_SRR0(r12); \
+ TLB_MISS_PROLOG_STATS
+
+/* And these are the matching epilogs that restores things
+ *
+ * There are 3 epilogs:
+ *
+ * - SUCCESS : Unwinds one level
+ * - ERROR : restore from level 0 and reset
+ * - ERROR_SPECIAL : restore from current level and reset
+ *
+ * Normal errors use ERROR, that is, they restore the initial fault context
+ * and trigger a fault. However, there is a special case for linear mapping
+ * errors. Those should basically never happen, but if they do happen, we
+ * want the error to point out the context that did that linear mapping
+ * fault, not the initial level 0 (basically, we got a bogus PGF or something
+ * like that). For userland errors on the linear mapping, there is no
+ * difference since those are always level 0 anyway
+ */
+
+#define TLB_MISS_RESTORE(freg) \
+ ld r14,EX_TLB_CR(r12); \
+ ld r10,EX_TLB_R10(r12); \
+ ld r15,EX_TLB_SRR0(r12); \
+ ld r16,EX_TLB_SRR1(r12); \
+ mtspr SPRN_SPRG_TLB_EXFRAME,freg; \
+ ld r11,EX_TLB_R11(r12); \
+ mtcr r14; \
+ ld r13,EX_TLB_R13(r12); \
+ ld r14,EX_TLB_R14(r12); \
+ mtspr SPRN_SRR0,r15; \
+ ld r15,EX_TLB_R15(r12); \
+ mtspr SPRN_SRR1,r16; \
+ TLB_MISS_RESTORE_STATS \
+ ld r16,EX_TLB_R16(r12); \
+ ld r12,EX_TLB_R12(r12); \
+
+#define TLB_MISS_EPILOG_SUCCESS \
+ TLB_MISS_RESTORE(r12)
+
+#define TLB_MISS_EPILOG_ERROR \
+ addi r12,r13,PACA_EXTLB; \
+ TLB_MISS_RESTORE(r12)
+
+#define TLB_MISS_EPILOG_ERROR_SPECIAL \
+ addi r11,r13,PACA_EXTLB; \
+ TLB_MISS_RESTORE(r11)
+
+#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
+#define TLB_MISS_PROLOG_STATS \
+ mflr r10; \
+ std r8,EX_TLB_R8(r12); \
+ std r9,EX_TLB_R9(r12); \
+ std r10,EX_TLB_LR(r12);
+#define TLB_MISS_RESTORE_STATS \
+ ld r16,EX_TLB_LR(r12); \
+ ld r9,EX_TLB_R9(r12); \
+ ld r8,EX_TLB_R8(r12); \
+ mtlr r16;
+#define TLB_MISS_STATS_D(name) \
+ addi r9,r13,MMSTAT_DSTATS+name; \
+ bl .tlb_stat_inc;
+#define TLB_MISS_STATS_I(name) \
+ addi r9,r13,MMSTAT_ISTATS+name; \
+ bl .tlb_stat_inc;
+#define TLB_MISS_STATS_X(name) \
+ ld r8,PACA_EXTLB+EX_TLB_ESR(r13); \
+ cmpdi cr2,r8,-1; \
+ beq cr2,61f; \
+ addi r9,r13,MMSTAT_DSTATS+name; \
+ b 62f; \
+61: addi r9,r13,MMSTAT_ISTATS+name; \
+62: bl .tlb_stat_inc;
+#define TLB_MISS_STATS_SAVE_INFO \
+ std r14,EX_TLB_ESR(r12); /* save ESR */ \
+
+
+#else
+#define TLB_MISS_PROLOG_STATS
+#define TLB_MISS_RESTORE_STATS
+#define TLB_MISS_STATS_D(name)
+#define TLB_MISS_STATS_I(name)
+#define TLB_MISS_STATS_X(name)
+#define TLB_MISS_STATS_Y(name)
+#define TLB_MISS_STATS_SAVE_INFO
+#endif
+
+
+#endif /* _ASM_POWERPC_EXCEPTION_64E_H */
+
projects / platform / kernel / linux-rpi.git / commitdiff