forked from Minki/linux
ee8348496c
Commit863771a28e("powerpc/32s: Convert switch_mmu_context() to C") moved the switch_mmu_context() to C. While in principle a good idea, it meant that the function now uses the stack. The stack is not accessible from real mode though. So to keep calling the function, let's turn on MSR_DR while we call it. That way, all pointer references to the stack are handled virtually. In addition, make sure to save/restore r12 on the stack, as it may get clobbered by the C function. Fixes:863771a28e("powerpc/32s: Convert switch_mmu_context() to C") Cc: stable@vger.kernel.org # v5.14+ Reported-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Alexander Graf <graf@amazon.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220510123717.24508-1-graf@amazon.com
149 lines
3.4 KiB
ArmAsm
149 lines
3.4 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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*
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* Copyright SUSE Linux Products GmbH 2009
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*
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* Authors: Alexander Graf <agraf@suse.de>
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*/
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/******************************************************************************
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* *
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* Entry code *
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* *
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*****************************************************************************/
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.macro LOAD_GUEST_SEGMENTS
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/* Required state:
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*
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* MSR = ~IR|DR
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* R1 = host R1
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* R2 = host R2
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* R3 = shadow vcpu
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* all other volatile GPRS = free except R4, R6
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* SVCPU[CR] = guest CR
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* SVCPU[XER] = guest XER
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* SVCPU[CTR] = guest CTR
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* SVCPU[LR] = guest LR
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*/
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#define XCHG_SR(n) lwz r9, (SVCPU_SR+(n*4))(r3); \
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mtsr n, r9
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XCHG_SR(0)
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XCHG_SR(1)
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XCHG_SR(2)
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XCHG_SR(3)
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XCHG_SR(4)
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XCHG_SR(5)
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XCHG_SR(6)
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XCHG_SR(7)
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XCHG_SR(8)
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XCHG_SR(9)
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XCHG_SR(10)
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XCHG_SR(11)
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XCHG_SR(12)
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XCHG_SR(13)
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XCHG_SR(14)
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XCHG_SR(15)
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/* Clear BATs. */
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#define KVM_KILL_BAT(n, reg) \
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mtspr SPRN_IBAT##n##U,reg; \
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mtspr SPRN_IBAT##n##L,reg; \
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mtspr SPRN_DBAT##n##U,reg; \
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mtspr SPRN_DBAT##n##L,reg; \
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li r9, 0
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KVM_KILL_BAT(0, r9)
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KVM_KILL_BAT(1, r9)
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KVM_KILL_BAT(2, r9)
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KVM_KILL_BAT(3, r9)
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.endm
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/******************************************************************************
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* *
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* Exit code *
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* *
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*****************************************************************************/
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.macro LOAD_HOST_SEGMENTS
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/* Register usage at this point:
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*
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* R1 = host R1
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* R2 = host R2
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* R12 = exit handler id
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* R13 = shadow vcpu - SHADOW_VCPU_OFF
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* SVCPU.* = guest *
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* SVCPU[CR] = guest CR
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* SVCPU[XER] = guest XER
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* SVCPU[CTR] = guest CTR
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* SVCPU[LR] = guest LR
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*
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*/
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/* Restore BATs */
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/* We only overwrite the upper part, so we only restoree
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the upper part. */
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#define KVM_LOAD_BAT(n, reg, RA, RB) \
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lwz RA,(n*16)+0(reg); \
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lwz RB,(n*16)+4(reg); \
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mtspr SPRN_IBAT##n##U,RA; \
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mtspr SPRN_IBAT##n##L,RB; \
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lwz RA,(n*16)+8(reg); \
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lwz RB,(n*16)+12(reg); \
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mtspr SPRN_DBAT##n##U,RA; \
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mtspr SPRN_DBAT##n##L,RB; \
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lis r9, BATS@ha
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addi r9, r9, BATS@l
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tophys(r9, r9)
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KVM_LOAD_BAT(0, r9, r10, r11)
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KVM_LOAD_BAT(1, r9, r10, r11)
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KVM_LOAD_BAT(2, r9, r10, r11)
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KVM_LOAD_BAT(3, r9, r10, r11)
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/* Restore Segment Registers */
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/* 0xc - 0xf */
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li r0, 4
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mtctr r0
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LOAD_REG_IMMEDIATE(r3, 0x20000000 | (0x111 * 0xc))
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lis r4, 0xc000
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3: mtsrin r3, r4
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addi r3, r3, 0x111 /* increment VSID */
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addis r4, r4, 0x1000 /* address of next segment */
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bdnz 3b
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/* 0x0 - 0xb */
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/* switch_mmu_context() needs paging, let's enable it */
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mfmsr r9
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ori r11, r9, MSR_DR
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mtmsr r11
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sync
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/* switch_mmu_context() clobbers r12, rescue it */
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SAVE_GPR(12, r1)
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/* Calling switch_mmu_context(<inv>, current->mm, <inv>); */
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lwz r4, MM(r2)
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bl switch_mmu_context
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/* restore r12 */
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REST_GPR(12, r1)
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/* Disable paging again */
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mfmsr r9
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li r6, MSR_DR
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andc r9, r9, r6
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mtmsr r9
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sync
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.endm
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