/* 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) #ifndef __ASSEMBLY__ extern unsigned int interrupt_base_book3e; #endif #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 */