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5aec715d7d
Our current switch_mm implementation suffers from a number of problems:
(1) The ASID allocator relies on IPIs to synchronise the CPUs on a
rollover event
(2) Because of (1), we cannot allocate ASIDs with interrupts disabled
and therefore make use of a TIF_SWITCH_MM flag to postpone the
actual switch to finish_arch_post_lock_switch
(3) We run context switch with a reserved (invalid) TTBR0 value, even
though the ASID and pgd are updated atomically
(4) We take a global spinlock (cpu_asid_lock) during context-switch
(5) We use h/w broadcast TLB operations when they are not required
(e.g. in flush_context)
This patch addresses these problems by rewriting the ASID algorithm to
match the bitmap-based arch/arm/ implementation more closely. This in
turn allows us to remove much of the complications surrounding switch_mm,
including the ugly thread flag.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
228 lines
5.3 KiB
ArmAsm
228 lines
5.3 KiB
ArmAsm
/*
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* Based on arch/arm/mm/proc.S
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*
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* Copyright (C) 2001 Deep Blue Solutions Ltd.
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* Copyright (C) 2012 ARM Ltd.
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* Author: Catalin Marinas <catalin.marinas@arm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/init.h>
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/asm-offsets.h>
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#include <asm/hwcap.h>
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#include <asm/pgtable-hwdef.h>
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#include <asm/pgtable.h>
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#include "proc-macros.S"
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#ifdef CONFIG_ARM64_64K_PAGES
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#define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
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#else
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#define TCR_TG_FLAGS TCR_TG0_4K | TCR_TG1_4K
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#endif
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#define TCR_SMP_FLAGS TCR_SHARED
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/* PTWs cacheable, inner/outer WBWA */
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#define TCR_CACHE_FLAGS TCR_IRGN_WBWA | TCR_ORGN_WBWA
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#define MAIR(attr, mt) ((attr) << ((mt) * 8))
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/*
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* cpu_do_idle()
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*
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* Idle the processor (wait for interrupt).
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*/
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ENTRY(cpu_do_idle)
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dsb sy // WFI may enter a low-power mode
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wfi
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ret
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ENDPROC(cpu_do_idle)
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#ifdef CONFIG_CPU_PM
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/**
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* cpu_do_suspend - save CPU registers context
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*
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* x0: virtual address of context pointer
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*/
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ENTRY(cpu_do_suspend)
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mrs x2, tpidr_el0
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mrs x3, tpidrro_el0
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mrs x4, contextidr_el1
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mrs x5, mair_el1
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mrs x6, cpacr_el1
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mrs x7, ttbr1_el1
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mrs x8, tcr_el1
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mrs x9, vbar_el1
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mrs x10, mdscr_el1
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mrs x11, oslsr_el1
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mrs x12, sctlr_el1
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stp x2, x3, [x0]
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stp x4, x5, [x0, #16]
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stp x6, x7, [x0, #32]
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stp x8, x9, [x0, #48]
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stp x10, x11, [x0, #64]
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str x12, [x0, #80]
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ret
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ENDPROC(cpu_do_suspend)
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/**
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* cpu_do_resume - restore CPU register context
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*
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* x0: Physical address of context pointer
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* x1: ttbr0_el1 to be restored
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*
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* Returns:
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* sctlr_el1 value in x0
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*/
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ENTRY(cpu_do_resume)
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/*
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* Invalidate local tlb entries before turning on MMU
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*/
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tlbi vmalle1
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ldp x2, x3, [x0]
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ldp x4, x5, [x0, #16]
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ldp x6, x7, [x0, #32]
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ldp x8, x9, [x0, #48]
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ldp x10, x11, [x0, #64]
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ldr x12, [x0, #80]
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msr tpidr_el0, x2
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msr tpidrro_el0, x3
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msr contextidr_el1, x4
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msr mair_el1, x5
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msr cpacr_el1, x6
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msr ttbr0_el1, x1
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msr ttbr1_el1, x7
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tcr_set_idmap_t0sz x8, x7
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msr tcr_el1, x8
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msr vbar_el1, x9
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msr mdscr_el1, x10
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/*
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* Restore oslsr_el1 by writing oslar_el1
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*/
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ubfx x11, x11, #1, #1
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msr oslar_el1, x11
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mov x0, x12
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dsb nsh // Make sure local tlb invalidation completed
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isb
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ret
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ENDPROC(cpu_do_resume)
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#endif
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/*
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* cpu_do_switch_mm(pgd_phys, tsk)
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*
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* Set the translation table base pointer to be pgd_phys.
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*
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* - pgd_phys - physical address of new TTB
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*/
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ENTRY(cpu_do_switch_mm)
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mmid x1, x1 // get mm->context.id
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bfi x0, x1, #48, #16 // set the ASID
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msr ttbr0_el1, x0 // set TTBR0
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isb
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ret
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ENDPROC(cpu_do_switch_mm)
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.section ".text.init", #alloc, #execinstr
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/*
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* __cpu_setup
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*
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* Initialise the processor for turning the MMU on. Return in x0 the
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* value of the SCTLR_EL1 register.
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*/
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ENTRY(__cpu_setup)
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tlbi vmalle1 // Invalidate local TLB
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dsb nsh
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mov x0, #3 << 20
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msr cpacr_el1, x0 // Enable FP/ASIMD
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mov x0, #1 << 12 // Reset mdscr_el1 and disable
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msr mdscr_el1, x0 // access to the DCC from EL0
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/*
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* Memory region attributes for LPAE:
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*
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* n = AttrIndx[2:0]
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* n MAIR
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* DEVICE_nGnRnE 000 00000000
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* DEVICE_nGnRE 001 00000100
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* DEVICE_GRE 010 00001100
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* NORMAL_NC 011 01000100
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* NORMAL 100 11111111
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*/
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ldr x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
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MAIR(0x04, MT_DEVICE_nGnRE) | \
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MAIR(0x0c, MT_DEVICE_GRE) | \
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MAIR(0x44, MT_NORMAL_NC) | \
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MAIR(0xff, MT_NORMAL)
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msr mair_el1, x5
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/*
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* Prepare SCTLR
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*/
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adr x5, crval
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ldp w5, w6, [x5]
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mrs x0, sctlr_el1
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bic x0, x0, x5 // clear bits
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orr x0, x0, x6 // set bits
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/*
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* Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
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* both user and kernel.
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*/
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ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
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TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0
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tcr_set_idmap_t0sz x10, x9
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/*
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* Read the PARange bits from ID_AA64MMFR0_EL1 and set the IPS bits in
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* TCR_EL1.
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*/
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mrs x9, ID_AA64MMFR0_EL1
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bfi x10, x9, #32, #3
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#ifdef CONFIG_ARM64_HW_AFDBM
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/*
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* Hardware update of the Access and Dirty bits.
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*/
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mrs x9, ID_AA64MMFR1_EL1
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and x9, x9, #0xf
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cbz x9, 2f
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cmp x9, #2
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b.lt 1f
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orr x10, x10, #TCR_HD // hardware Dirty flag update
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1: orr x10, x10, #TCR_HA // hardware Access flag update
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2:
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#endif /* CONFIG_ARM64_HW_AFDBM */
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msr tcr_el1, x10
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ret // return to head.S
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ENDPROC(__cpu_setup)
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/*
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* We set the desired value explicitly, including those of the
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* reserved bits. The values of bits EE & E0E were set early in
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* el2_setup, which are left untouched below.
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*
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* n n T
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* U E WT T UD US IHBS
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* CE0 XWHW CZ ME TEEA S
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* .... .IEE .... NEAI TE.I ..AD DEN0 ACAM
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* 0011 0... 1101 ..0. ..0. 10.. .0.. .... < hardware reserved
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* .... .1.. .... 01.1 11.1 ..01 0.01 1101 < software settings
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*/
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.type crval, #object
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crval:
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.word 0xfcffffff // clear
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.word 0x34d5d91d // set
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