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Diffstat (limited to 'arch/powerpc/include/asm/exception-64e.h')
| -rw-r--r-- | arch/powerpc/include/asm/exception-64e.h | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/exception-64e.h b/arch/powerpc/include/asm/exception-64e.h new file mode 100644 index 000000000..40cdcb2fb --- /dev/null +++ b/arch/powerpc/include/asm/exception-64e.h @@ -0,0 +1,168 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Definitions for use by exception code on Book3-E + * + * Copyright (C) 2008 Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp. + */ +#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 + */ + +#define PACA_EXGDBELL PACA_EXGEN + +/* 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. + * + * The bolted variant uses only the first six fields, + * which in combination with pgd and kernel_pgd fits in + * one 64-byte cache line. + */ + +#define EX_TLB_R10 ( 0 * 8) +#define EX_TLB_R11 ( 1 * 8) +#define EX_TLB_R14 ( 2 * 8) +#define EX_TLB_R15 ( 3 * 8) +#define EX_TLB_R16 ( 4 * 8) +#define EX_TLB_CR ( 5 * 8) +#define EX_TLB_R12 ( 6 * 8) +#define EX_TLB_R13 ( 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_R7 (12 * 8) +#define EX_TLB_SIZE (13 * 8) + +#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); + +/* 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; \ + 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) + +#define SET_IVOR(vector_number, vector_offset) \ + LOAD_REG_ADDR(r3,interrupt_base_book3e);\ + ori r3,r3,vector_offset@l; \ + mtspr SPRN_IVOR##vector_number,r3; +/* + * powerpc relies on return from interrupt/syscall being context synchronising + * (which rfi is) to support ARCH_HAS_MEMBARRIER_SYNC_CORE without additional + * synchronisation instructions. + */ +#define RFI_TO_KERNEL \ + rfi + +#define RFI_TO_USER \ + rfi + +#endif /* _ASM_POWERPC_EXCEPTION_64E_H */ + |