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bcba6b9024
commit 50e51c13b3 upstream.
The rfid/hrfid ((Hypervisor) Return From Interrupt) instruction is
used for switching from the kernel to userspace, and from the
hypervisor to the guest kernel. However it can and is also used for
other transitions, eg. from real mode kernel code to virtual mode
kernel code, and it's not always clear from the code what the
destination context is.
To make it clearer when reading the code, add macros which encode the
expected destination context.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
220 lines
7.2 KiB
C
220 lines
7.2 KiB
C
/*
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* Definitions for use by exception code on Book3-E
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*
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* Copyright (C) 2008 Ben. Herrenschmidt (benh@kernel.crashing.org), IBM Corp.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#ifndef _ASM_POWERPC_EXCEPTION_64E_H
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#define _ASM_POWERPC_EXCEPTION_64E_H
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/*
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* SPRGs usage an other considerations...
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*
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* Since TLB miss and other standard exceptions can be interrupted by
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* critical exceptions which can themselves be interrupted by machine
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* checks, and since the two later can themselves cause a TLB miss when
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* hitting the linear mapping for the kernel stacks, we need to be a bit
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* creative on how we use SPRGs.
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*
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* The base idea is that we have one SRPG reserved for critical and one
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* for machine check interrupts. Those are used to save a GPR that can
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* then be used to get the PACA, and store as much context as we need
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* to save in there. That includes saving the SPRGs used by the TLB miss
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* handler for linear mapping misses and the associated SRR0/1 due to
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* the above re-entrancy issue.
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*
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* So here's the current usage pattern. It's done regardless of which
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* SPRGs are user-readable though, thus we might have to change some of
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* this later. In order to do that more easily, we use special constants
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* for naming them
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*
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* WARNING: Some of these SPRGs are user readable. We need to do something
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* about it as some point by making sure they can't be used to leak kernel
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* critical data
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*/
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#define PACA_EXGDBELL PACA_EXGEN
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/* We are out of SPRGs so we save some things in the PACA. The normal
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* exception frame is smaller than the CRIT or MC one though
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*/
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#define EX_R1 (0 * 8)
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#define EX_CR (1 * 8)
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#define EX_R10 (2 * 8)
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#define EX_R11 (3 * 8)
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#define EX_R14 (4 * 8)
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#define EX_R15 (5 * 8)
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/*
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* The TLB miss exception uses different slots.
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*
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* The bolted variant uses only the first six fields,
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* which in combination with pgd and kernel_pgd fits in
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* one 64-byte cache line.
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*/
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#define EX_TLB_R10 ( 0 * 8)
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#define EX_TLB_R11 ( 1 * 8)
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#define EX_TLB_R14 ( 2 * 8)
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#define EX_TLB_R15 ( 3 * 8)
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#define EX_TLB_R16 ( 4 * 8)
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#define EX_TLB_CR ( 5 * 8)
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#define EX_TLB_R12 ( 6 * 8)
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#define EX_TLB_R13 ( 7 * 8)
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#define EX_TLB_DEAR ( 8 * 8) /* Level 0 and 2 only */
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#define EX_TLB_ESR ( 9 * 8) /* Level 0 and 2 only */
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#define EX_TLB_SRR0 (10 * 8)
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#define EX_TLB_SRR1 (11 * 8)
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#define EX_TLB_R7 (12 * 8)
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#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
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#define EX_TLB_R8 (13 * 8)
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#define EX_TLB_R9 (14 * 8)
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#define EX_TLB_LR (15 * 8)
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#define EX_TLB_SIZE (16 * 8)
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#else
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#define EX_TLB_SIZE (13 * 8)
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#endif
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#define START_EXCEPTION(label) \
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.globl exc_##label##_book3e; \
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exc_##label##_book3e:
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/* TLB miss exception prolog
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*
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* This prolog handles re-entrancy (up to 3 levels supported in the PACA
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* though we currently don't test for overflow). It provides you with a
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* re-entrancy safe working space of r10...r16 and CR with r12 being used
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* as the exception area pointer in the PACA for that level of re-entrancy
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* and r13 containing the PACA pointer.
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*
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* SRR0 and SRR1 are saved, but DEAR and ESR are not, since they don't apply
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* as-is for instruction exceptions. It's up to the actual exception code
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* to save them as well if required.
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*/
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#define TLB_MISS_PROLOG \
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mtspr SPRN_SPRG_TLB_SCRATCH,r12; \
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mfspr r12,SPRN_SPRG_TLB_EXFRAME; \
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std r10,EX_TLB_R10(r12); \
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mfcr r10; \
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std r11,EX_TLB_R11(r12); \
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mfspr r11,SPRN_SPRG_TLB_SCRATCH; \
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std r13,EX_TLB_R13(r12); \
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mfspr r13,SPRN_SPRG_PACA; \
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std r14,EX_TLB_R14(r12); \
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addi r14,r12,EX_TLB_SIZE; \
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std r15,EX_TLB_R15(r12); \
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mfspr r15,SPRN_SRR1; \
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std r16,EX_TLB_R16(r12); \
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mfspr r16,SPRN_SRR0; \
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std r10,EX_TLB_CR(r12); \
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std r11,EX_TLB_R12(r12); \
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mtspr SPRN_SPRG_TLB_EXFRAME,r14; \
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std r15,EX_TLB_SRR1(r12); \
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std r16,EX_TLB_SRR0(r12); \
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TLB_MISS_PROLOG_STATS
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/* And these are the matching epilogs that restores things
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*
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* There are 3 epilogs:
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*
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* - SUCCESS : Unwinds one level
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* - ERROR : restore from level 0 and reset
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* - ERROR_SPECIAL : restore from current level and reset
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*
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* Normal errors use ERROR, that is, they restore the initial fault context
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* and trigger a fault. However, there is a special case for linear mapping
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* errors. Those should basically never happen, but if they do happen, we
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* want the error to point out the context that did that linear mapping
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* fault, not the initial level 0 (basically, we got a bogus PGF or something
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* like that). For userland errors on the linear mapping, there is no
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* difference since those are always level 0 anyway
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*/
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#define TLB_MISS_RESTORE(freg) \
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ld r14,EX_TLB_CR(r12); \
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ld r10,EX_TLB_R10(r12); \
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ld r15,EX_TLB_SRR0(r12); \
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ld r16,EX_TLB_SRR1(r12); \
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mtspr SPRN_SPRG_TLB_EXFRAME,freg; \
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ld r11,EX_TLB_R11(r12); \
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mtcr r14; \
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ld r13,EX_TLB_R13(r12); \
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ld r14,EX_TLB_R14(r12); \
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mtspr SPRN_SRR0,r15; \
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ld r15,EX_TLB_R15(r12); \
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mtspr SPRN_SRR1,r16; \
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TLB_MISS_RESTORE_STATS \
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ld r16,EX_TLB_R16(r12); \
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ld r12,EX_TLB_R12(r12); \
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#define TLB_MISS_EPILOG_SUCCESS \
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TLB_MISS_RESTORE(r12)
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#define TLB_MISS_EPILOG_ERROR \
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addi r12,r13,PACA_EXTLB; \
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TLB_MISS_RESTORE(r12)
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#define TLB_MISS_EPILOG_ERROR_SPECIAL \
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addi r11,r13,PACA_EXTLB; \
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TLB_MISS_RESTORE(r11)
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#ifdef CONFIG_BOOK3E_MMU_TLB_STATS
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#define TLB_MISS_PROLOG_STATS \
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mflr r10; \
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std r8,EX_TLB_R8(r12); \
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std r9,EX_TLB_R9(r12); \
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std r10,EX_TLB_LR(r12);
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#define TLB_MISS_RESTORE_STATS \
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ld r16,EX_TLB_LR(r12); \
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ld r9,EX_TLB_R9(r12); \
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ld r8,EX_TLB_R8(r12); \
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mtlr r16;
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#define TLB_MISS_STATS_D(name) \
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addi r9,r13,MMSTAT_DSTATS+name; \
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bl tlb_stat_inc;
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#define TLB_MISS_STATS_I(name) \
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addi r9,r13,MMSTAT_ISTATS+name; \
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bl tlb_stat_inc;
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#define TLB_MISS_STATS_X(name) \
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ld r8,PACA_EXTLB+EX_TLB_ESR(r13); \
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cmpdi cr2,r8,-1; \
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beq cr2,61f; \
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addi r9,r13,MMSTAT_DSTATS+name; \
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b 62f; \
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61: addi r9,r13,MMSTAT_ISTATS+name; \
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62: bl tlb_stat_inc;
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#define TLB_MISS_STATS_SAVE_INFO \
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std r14,EX_TLB_ESR(r12); /* save ESR */
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#define TLB_MISS_STATS_SAVE_INFO_BOLTED \
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std r14,PACA_EXTLB+EX_TLB_ESR(r13); /* save ESR */
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#else
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#define TLB_MISS_PROLOG_STATS
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#define TLB_MISS_RESTORE_STATS
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#define TLB_MISS_PROLOG_STATS_BOLTED
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#define TLB_MISS_RESTORE_STATS_BOLTED
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#define TLB_MISS_STATS_D(name)
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#define TLB_MISS_STATS_I(name)
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#define TLB_MISS_STATS_X(name)
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#define TLB_MISS_STATS_Y(name)
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#define TLB_MISS_STATS_SAVE_INFO
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#define TLB_MISS_STATS_SAVE_INFO_BOLTED
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#endif
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#define SET_IVOR(vector_number, vector_offset) \
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LOAD_REG_ADDR(r3,interrupt_base_book3e);\
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ori r3,r3,vector_offset@l; \
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mtspr SPRN_IVOR##vector_number,r3;
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#define RFI_TO_KERNEL \
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rfi
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#define RFI_TO_USER \
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rfi
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#endif /* _ASM_POWERPC_EXCEPTION_64E_H */
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