Current File : //usr/src/linux-headers-5.15.0-43/arch/powerpc/include/asm/exception-64e.h
/* 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 */
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