arch/arm64/mm/proc.S - linux - Git at Google

 /*
  * Based on arch/arm/mm/proc.S
  *
  * Copyright (C) 2001 Deep Blue Solutions Ltd.
  * Copyright (C) 2012 ARM Ltd.
  * Author: Catalin Marinas <catalin.marinas@arm.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/init.h>
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 #include <asm/asm-offsets.h>
 #include <asm/hwcap.h>
 #include <asm/pgtable.h>
 #include <asm/pgtable-hwdef.h>
 #include <asm/cpufeature.h>
 #include <asm/alternative.h>

 #ifdef CONFIG_ARM64_64K_PAGES
 #define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
 #elif defined(CONFIG_ARM64_16K_PAGES)
 #define TCR_TG_FLAGS	TCR_TG0_16K | TCR_TG1_16K
 #else /* CONFIG_ARM64_4K_PAGES */
 #define TCR_TG_FLAGS	TCR_TG0_4K | TCR_TG1_4K
 #endif

 #ifdef CONFIG_RANDOMIZE_BASE
 #define TCR_KASLR_FLAGS	TCR_NFD1
 #else
 #define TCR_KASLR_FLAGS	0
 #endif

 #define TCR_SMP_FLAGS	TCR_SHARED

 /* PTWs cacheable, inner/outer WBWA */
 #define TCR_CACHE_FLAGS	TCR_IRGN_WBWA | TCR_ORGN_WBWA

 #ifdef CONFIG_KASAN_SW_TAGS
 #define TCR_KASAN_FLAGS TCR_TBI1
 #else
 #define TCR_KASAN_FLAGS 0
 #endif

 #define MAIR(attr, mt)	((attr) << ((mt) * 8))

 #ifdef CONFIG_CPU_PM
 /**
  * cpu_do_suspend - save CPU registers context
  *
  * x0: virtual address of context pointer
  */
 ENTRY(cpu_do_suspend)
 	mrs	x2, tpidr_el0
 	mrs	x3, tpidrro_el0
 	mrs	x4, contextidr_el1
 	mrs	x5, osdlr_el1
 	mrs	x6, cpacr_el1
 	mrs	x7, tcr_el1
 	mrs	x8, vbar_el1
 	mrs	x9, mdscr_el1
 	mrs	x10, oslsr_el1
 	mrs	x11, sctlr_el1
 alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
 	mrs	x12, tpidr_el1
 alternative_else
 	mrs	x12, tpidr_el2
 alternative_endif
 	mrs	x13, sp_el0
 	stp	x2, x3, [x0]
 	stp	x4, x5, [x0, #16]
 	stp	x6, x7, [x0, #32]
 	stp	x8, x9, [x0, #48]
 	stp	x10, x11, [x0, #64]
 	stp	x12, x13, [x0, #80]
 	ret
 ENDPROC(cpu_do_suspend)

 /**
  * cpu_do_resume - restore CPU register context
  *
  * x0: Address of context pointer
  */
 	.pushsection ".idmap.text", "awx"
 ENTRY(cpu_do_resume)
 	ldp	x2, x3, [x0]
 	ldp	x4, x5, [x0, #16]
 	ldp	x6, x8, [x0, #32]
 	ldp	x9, x10, [x0, #48]
 	ldp	x11, x12, [x0, #64]
 	ldp	x13, x14, [x0, #80]
 	msr	tpidr_el0, x2
 	msr	tpidrro_el0, x3
 	msr	contextidr_el1, x4
 	msr	cpacr_el1, x6

 	/* Don't change t0sz here, mask those bits when restoring */
 	mrs	x7, tcr_el1
 	bfi	x8, x7, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH

 	msr	tcr_el1, x8
 	msr	vbar_el1, x9

 	/*
 	 * __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
 	 * debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
 	 * exception. Mask them until local_daif_restore() in cpu_suspend()
 	 * resets them.
 	 */
 	disable_daif
 	msr	mdscr_el1, x10

 	msr	sctlr_el1, x12
 alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
 	msr	tpidr_el1, x13
 alternative_else
 	msr	tpidr_el2, x13
 alternative_endif
 	msr	sp_el0, x14
 	/*
 	 * Restore oslsr_el1 by writing oslar_el1
 	 */
 	msr	osdlr_el1, x5
 	ubfx	x11, x11, #1, #1
 	msr	oslar_el1, x11
 	reset_pmuserenr_el0 x0			// Disable PMU access from EL0

 alternative_if ARM64_HAS_RAS_EXTN
 	msr_s	SYS_DISR_EL1, xzr
 alternative_else_nop_endif

 	isb
 	ret
 ENDPROC(cpu_do_resume)
 	.popsection
 #endif

 /*
  *	cpu_do_switch_mm(pgd_phys, tsk)
  *
  *	Set the translation table base pointer to be pgd_phys.
  *
  *	- pgd_phys - physical address of new TTB
  */
 ENTRY(cpu_do_switch_mm)
 	mrs	x2, ttbr1_el1
 	mmid	x1, x1				// get mm->context.id
 	phys_to_ttbr x3, x0

 alternative_if ARM64_HAS_CNP
 	cbz     x1, 1f                          // skip CNP for reserved ASID
 	orr     x3, x3, #TTBR_CNP_BIT
 1:
 alternative_else_nop_endif
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	bfi	x3, x1, #48, #16		// set the ASID field in TTBR0
 #endif
 	bfi	x2, x1, #48, #16		// set the ASID
 	msr	ttbr1_el1, x2			// in TTBR1 (since TCR.A1 is set)
 	isb
 	msr	ttbr0_el1, x3			// now update TTBR0
 	isb
 	b	post_ttbr_update_workaround	// Back to C code...
 ENDPROC(cpu_do_switch_mm)

 	.pushsection ".idmap.text", "awx"

 .macro	__idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
 	adrp	\tmp1, empty_zero_page
 	phys_to_ttbr \tmp2, \tmp1
 	offset_ttbr1 \tmp2
 	msr	ttbr1_el1, \tmp2
 	isb
 	tlbi	vmalle1
 	dsb	nsh
 	isb
 .endm

 /*
  * void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
  *
  * This is the low-level counterpart to cpu_replace_ttbr1, and should not be
  * called by anything else. It can only be executed from a TTBR0 mapping.
  */
 ENTRY(idmap_cpu_replace_ttbr1)
 	save_and_disable_daif flags=x2

 	__idmap_cpu_set_reserved_ttbr1 x1, x3

 	offset_ttbr1 x0
 	msr	ttbr1_el1, x0
 	isb

 	restore_daif x2

 	ret
 ENDPROC(idmap_cpu_replace_ttbr1)
 	.popsection

 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
 	.pushsection ".idmap.text", "awx"

 	.macro	__idmap_kpti_get_pgtable_ent, type
 	dc	cvac, cur_\()\type\()p		// Ensure any existing dirty
 	dmb	sy				// lines are written back before
 	ldr	\type, [cur_\()\type\()p]	// loading the entry
 	tbz	\type, #0, skip_\()\type	// Skip invalid and
 	tbnz	\type, #11, skip_\()\type	// non-global entries
 	.endm

 	.macro __idmap_kpti_put_pgtable_ent_ng, type
 	orr	\type, \type, #PTE_NG		// Same bit for blocks and pages
 	str	\type, [cur_\()\type\()p]	// Update the entry and ensure
 	dmb	sy				// that it is visible to all
 	dc	civac, cur_\()\type\()p		// CPUs.
 	.endm

 /*
  * void __kpti_install_ng_mappings(int cpu, int num_cpus, phys_addr_t swapper)
  *
  * Called exactly once from stop_machine context by each CPU found during boot.
  */
 __idmap_kpti_flag:
 	.long	1
 ENTRY(idmap_kpti_install_ng_mappings)
 	cpu		.req	w0
 	num_cpus	.req	w1
 	swapper_pa	.req	x2
 	swapper_ttb	.req	x3
 	flag_ptr	.req	x4
 	cur_pgdp	.req	x5
 	end_pgdp	.req	x6
 	pgd		.req	x7
 	cur_pudp	.req	x8
 	end_pudp	.req	x9
 	pud		.req	x10
 	cur_pmdp	.req	x11
 	end_pmdp	.req	x12
 	pmd		.req	x13
 	cur_ptep	.req	x14
 	end_ptep	.req	x15
 	pte		.req	x16

 	mrs	swapper_ttb, ttbr1_el1
 	restore_ttbr1	swapper_ttb
 	adr	flag_ptr, __idmap_kpti_flag

 	cbnz	cpu, __idmap_kpti_secondary

 	/* We're the boot CPU. Wait for the others to catch up */
 	sevl
 1:	wfe
 	ldaxr	w18, [flag_ptr]
 	eor	w18, w18, num_cpus
 	cbnz	w18, 1b

 	/* We need to walk swapper, so turn off the MMU. */
 	pre_disable_mmu_workaround
 	mrs	x18, sctlr_el1
 	bic	x18, x18, #SCTLR_ELx_M
 	msr	sctlr_el1, x18
 	isb

 	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
 	/* PGD */
 	mov	cur_pgdp, swapper_pa
 	add	end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8)
 do_pgd:	__idmap_kpti_get_pgtable_ent	pgd
 	tbnz	pgd, #1, walk_puds
 next_pgd:
 	__idmap_kpti_put_pgtable_ent_ng	pgd
 skip_pgd:
 	add	cur_pgdp, cur_pgdp, #8
 	cmp	cur_pgdp, end_pgdp
 	b.ne	do_pgd

 	/* Publish the updated tables and nuke all the TLBs */
 	dsb	sy
 	tlbi	vmalle1is
 	dsb	ish
 	isb

 	/* We're done: fire up the MMU again */
 	mrs	x18, sctlr_el1
 	orr	x18, x18, #SCTLR_ELx_M
 	msr	sctlr_el1, x18
 	isb

 	/* Set the flag to zero to indicate that we're all done */
 	str	wzr, [flag_ptr]
 	ret

 	/* PUD */
 walk_puds:
 	.if CONFIG_PGTABLE_LEVELS > 3
 	pte_to_phys	cur_pudp, pgd
 	add	end_pudp, cur_pudp, #(PTRS_PER_PUD * 8)
 do_pud:	__idmap_kpti_get_pgtable_ent	pud
 	tbnz	pud, #1, walk_pmds
 next_pud:
 	__idmap_kpti_put_pgtable_ent_ng	pud
 skip_pud:
 	add	cur_pudp, cur_pudp, 8
 	cmp	cur_pudp, end_pudp
 	b.ne	do_pud
 	b	next_pgd
 	.else /* CONFIG_PGTABLE_LEVELS <= 3 */
 	mov	pud, pgd
 	b	walk_pmds
 next_pud:
 	b	next_pgd
 	.endif

 	/* PMD */
 walk_pmds:
 	.if CONFIG_PGTABLE_LEVELS > 2
 	pte_to_phys	cur_pmdp, pud
 	add	end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8)
 do_pmd:	__idmap_kpti_get_pgtable_ent	pmd
 	tbnz	pmd, #1, walk_ptes
 next_pmd:
 	__idmap_kpti_put_pgtable_ent_ng	pmd
 skip_pmd:
 	add	cur_pmdp, cur_pmdp, #8
 	cmp	cur_pmdp, end_pmdp
 	b.ne	do_pmd
 	b	next_pud
 	.else /* CONFIG_PGTABLE_LEVELS <= 2 */
 	mov	pmd, pud
 	b	walk_ptes
 next_pmd:
 	b	next_pud
 	.endif

 	/* PTE */
 walk_ptes:
 	pte_to_phys	cur_ptep, pmd
 	add	end_ptep, cur_ptep, #(PTRS_PER_PTE * 8)
 do_pte:	__idmap_kpti_get_pgtable_ent	pte
 	__idmap_kpti_put_pgtable_ent_ng	pte
 skip_pte:
 	add	cur_ptep, cur_ptep, #8
 	cmp	cur_ptep, end_ptep
 	b.ne	do_pte
 	b	next_pmd

 	/* Secondary CPUs end up here */
 __idmap_kpti_secondary:
 	/* Uninstall swapper before surgery begins */
 	__idmap_cpu_set_reserved_ttbr1 x18, x17

 	/* Increment the flag to let the boot CPU we're ready */
 1:	ldxr	w18, [flag_ptr]
 	add	w18, w18, #1
 	stxr	w17, w18, [flag_ptr]
 	cbnz	w17, 1b

 	/* Wait for the boot CPU to finish messing around with swapper */
 	sevl
 1:	wfe
 	ldxr	w18, [flag_ptr]
 	cbnz	w18, 1b

 	/* All done, act like nothing happened */
 	offset_ttbr1 swapper_ttb
 	msr	ttbr1_el1, swapper_ttb
 	isb
 	ret

 	.unreq	cpu
 	.unreq	num_cpus
 	.unreq	swapper_pa
 	.unreq	swapper_ttb
 	.unreq	flag_ptr
 	.unreq	cur_pgdp
 	.unreq	end_pgdp
 	.unreq	pgd
 	.unreq	cur_pudp
 	.unreq	end_pudp
 	.unreq	pud
 	.unreq	cur_pmdp
 	.unreq	end_pmdp
 	.unreq	pmd
 	.unreq	cur_ptep
 	.unreq	end_ptep
 	.unreq	pte
 ENDPROC(idmap_kpti_install_ng_mappings)
 	.popsection
 #endif

 /*
  *	__cpu_setup
  *
  *	Initialise the processor for turning the MMU on.  Return in x0 the
  *	value of the SCTLR_EL1 register.
  */
 	.pushsection ".idmap.text", "awx"
 ENTRY(__cpu_setup)
 	tlbi	vmalle1				// Invalidate local TLB
 	dsb	nsh

 	mov	x0, #3 << 20
 	msr	cpacr_el1, x0			// Enable FP/ASIMD
 	mov	x0, #1 << 12			// Reset mdscr_el1 and disable
 	msr	mdscr_el1, x0			// access to the DCC from EL0
 	isb					// Unmask debug exceptions now,
 	enable_dbg				// since this is per-cpu
 	reset_pmuserenr_el0 x0			// Disable PMU access from EL0
 	/*
 	 * Memory region attributes for LPAE:
 	 *
 	 *   n = AttrIndx[2:0]
 	 *			n	MAIR
 	 *   DEVICE_nGnRnE	000	00000000
 	 *   DEVICE_nGnRE	001	00000100
 	 *   DEVICE_GRE		010	00001100
 	 *   NORMAL_NC		011	01000100
 	 *   NORMAL		100	11111111
 	 *   NORMAL_WT		101	10111011
 	 */
 	ldr	x5, =MAIR(0x00, MT_DEVICE_nGnRnE) | \
 		     MAIR(0x04, MT_DEVICE_nGnRE) | \
 		     MAIR(0x0c, MT_DEVICE_GRE) | \
 		     MAIR(0x44, MT_NORMAL_NC) | \
 		     MAIR(0xff, MT_NORMAL) | \
 		     MAIR(0xbb, MT_NORMAL_WT)
 	msr	mair_el1, x5
 	/*
 	 * Prepare SCTLR
 	 */
 	mov_q	x0, SCTLR_EL1_SET
 	/*
 	 * Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
 	 * both user and kernel.
 	 */
 	ldr	x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
 			TCR_TG_FLAGS | TCR_KASLR_FLAGS | TCR_ASID16 | \
 			TCR_TBI0 | TCR_A1 | TCR_KASAN_FLAGS
 	tcr_clear_errata_bits x10, x9, x5

 #ifdef CONFIG_ARM64_USER_VA_BITS_52
 	ldr_l		x9, vabits_user
 	sub		x9, xzr, x9
 	add		x9, x9, #64
 #else
 	ldr_l		x9, idmap_t0sz
 #endif
 	tcr_set_t0sz	x10, x9

 	/*
 	 * Set the IPS bits in TCR_EL1.
 	 */
 	tcr_compute_pa_size x10, #TCR_IPS_SHIFT, x5, x6
 #ifdef CONFIG_ARM64_HW_AFDBM
 	/*
 	 * Enable hardware update of the Access Flags bit.
 	 * Hardware dirty bit management is enabled later,
 	 * via capabilities.
 	 */
 	mrs	x9, ID_AA64MMFR1_EL1
 	and	x9, x9, #0xf
 	cbz	x9, 1f
 	orr	x10, x10, #TCR_HA		// hardware Access flag update
 1:
 #endif	/* CONFIG_ARM64_HW_AFDBM */
 	msr	tcr_el1, x10
 	ret					// return to head.S
 ENDPROC(__cpu_setup)
	/*
	* Based on arch/arm/mm/proc.S
	*
	* Copyright (C) 2001 Deep Blue Solutions Ltd.
	* Copyright (C) 2012 ARM Ltd.
	* Author: Catalin Marinas <catalin.marinas@arm.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License version 2 as
	* published by the Free Software Foundation.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/init.h>
	#include <linux/linkage.h>
	#include <asm/assembler.h>
	#include <asm/asm-offsets.h>
	#include <asm/hwcap.h>
	#include <asm/pgtable.h>
	#include <asm/pgtable-hwdef.h>
	#include <asm/cpufeature.h>
	#include <asm/alternative.h>

	#ifdef CONFIG_ARM64_64K_PAGES
	#define TCR_TG_FLAGS TCR_TG0_64K \| TCR_TG1_64K
	#elif defined(CONFIG_ARM64_16K_PAGES)
	#define TCR_TG_FLAGS TCR_TG0_16K \| TCR_TG1_16K
	#else /* CONFIG_ARM64_4K_PAGES */
	#define TCR_TG_FLAGS TCR_TG0_4K \| TCR_TG1_4K
	#endif

	#ifdef CONFIG_RANDOMIZE_BASE
	#define TCR_KASLR_FLAGS TCR_NFD1
	#else
	#define TCR_KASLR_FLAGS 0
	#endif

	#define TCR_SMP_FLAGS TCR_SHARED

	/* PTWs cacheable, inner/outer WBWA */
	#define TCR_CACHE_FLAGS TCR_IRGN_WBWA \| TCR_ORGN_WBWA

	#ifdef CONFIG_KASAN_SW_TAGS
	#define TCR_KASAN_FLAGS TCR_TBI1
	#else
	#define TCR_KASAN_FLAGS 0
	#endif

	#define MAIR(attr, mt) ((attr) << ((mt) * 8))

	#ifdef CONFIG_CPU_PM
	/**
	* cpu_do_suspend - save CPU registers context
	*
	* x0: virtual address of context pointer
	*/
	ENTRY(cpu_do_suspend)
	mrs x2, tpidr_el0
	mrs x3, tpidrro_el0
	mrs x4, contextidr_el1
	mrs x5, osdlr_el1
	mrs x6, cpacr_el1
	mrs x7, tcr_el1
	mrs x8, vbar_el1
	mrs x9, mdscr_el1
	mrs x10, oslsr_el1
	mrs x11, sctlr_el1
	alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
	mrs x12, tpidr_el1
	alternative_else
	mrs x12, tpidr_el2
	alternative_endif
	mrs x13, sp_el0
	stp x2, x3, [x0]
	stp x4, x5, [x0, #16]
	stp x6, x7, [x0, #32]
	stp x8, x9, [x0, #48]
	stp x10, x11, [x0, #64]
	stp x12, x13, [x0, #80]
	ret
	ENDPROC(cpu_do_suspend)

	/**
	* cpu_do_resume - restore CPU register context
	*
	* x0: Address of context pointer
	*/
	.pushsection ".idmap.text", "awx"
	ENTRY(cpu_do_resume)
	ldp x2, x3, [x0]
	ldp x4, x5, [x0, #16]
	ldp x6, x8, [x0, #32]
	ldp x9, x10, [x0, #48]
	ldp x11, x12, [x0, #64]
	ldp x13, x14, [x0, #80]
	msr tpidr_el0, x2
	msr tpidrro_el0, x3
	msr contextidr_el1, x4
	msr cpacr_el1, x6

	/* Don't change t0sz here, mask those bits when restoring */
	mrs x7, tcr_el1
	bfi x8, x7, TCR_T0SZ_OFFSET, TCR_TxSZ_WIDTH

	msr tcr_el1, x8
	msr vbar_el1, x9

	/*
	* __cpu_setup() cleared MDSCR_EL1.MDE and friends, before unmasking
	* debug exceptions. By restoring MDSCR_EL1 here, we may take a debug
	* exception. Mask them until local_daif_restore() in cpu_suspend()
	* resets them.
	*/
	disable_daif
	msr mdscr_el1, x10

	msr sctlr_el1, x12
	alternative_if_not ARM64_HAS_VIRT_HOST_EXTN
	msr tpidr_el1, x13
	alternative_else
	msr tpidr_el2, x13
	alternative_endif
	msr sp_el0, x14
	/*
	* Restore oslsr_el1 by writing oslar_el1
	*/
	msr osdlr_el1, x5
	ubfx x11, x11, #1, #1
	msr oslar_el1, x11
	reset_pmuserenr_el0 x0 // Disable PMU access from EL0

	alternative_if ARM64_HAS_RAS_EXTN
	msr_s SYS_DISR_EL1, xzr
	alternative_else_nop_endif

	isb
	ret
	ENDPROC(cpu_do_resume)
	.popsection
	#endif

	/*
	* cpu_do_switch_mm(pgd_phys, tsk)
	*
	* Set the translation table base pointer to be pgd_phys.
	*
	* - pgd_phys - physical address of new TTB
	*/
	ENTRY(cpu_do_switch_mm)
	mrs x2, ttbr1_el1
	mmid x1, x1 // get mm->context.id
	phys_to_ttbr x3, x0

	alternative_if ARM64_HAS_CNP
	cbz x1, 1f // skip CNP for reserved ASID
	orr x3, x3, #TTBR_CNP_BIT
	1:
	alternative_else_nop_endif
	#ifdef CONFIG_ARM64_SW_TTBR0_PAN
	bfi x3, x1, #48, #16 // set the ASID field in TTBR0
	#endif
	bfi x2, x1, #48, #16 // set the ASID
	msr ttbr1_el1, x2 // in TTBR1 (since TCR.A1 is set)
	isb
	msr ttbr0_el1, x3 // now update TTBR0
	isb
	b post_ttbr_update_workaround // Back to C code...
	ENDPROC(cpu_do_switch_mm)

	.pushsection ".idmap.text", "awx"

	.macro __idmap_cpu_set_reserved_ttbr1, tmp1, tmp2
	adrp \tmp1, empty_zero_page
	phys_to_ttbr \tmp2, \tmp1
	offset_ttbr1 \tmp2
	msr ttbr1_el1, \tmp2
	isb
	tlbi vmalle1
	dsb nsh
	isb
	.endm

	/*
	* void idmap_cpu_replace_ttbr1(phys_addr_t ttbr1)
	*
	* This is the low-level counterpart to cpu_replace_ttbr1, and should not be
	* called by anything else. It can only be executed from a TTBR0 mapping.
	*/
	ENTRY(idmap_cpu_replace_ttbr1)
	save_and_disable_daif flags=x2

	__idmap_cpu_set_reserved_ttbr1 x1, x3

	offset_ttbr1 x0
	msr ttbr1_el1, x0
	isb

	restore_daif x2

	ret
	ENDPROC(idmap_cpu_replace_ttbr1)
	.popsection

	#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
	.pushsection ".idmap.text", "awx"

	.macro __idmap_kpti_get_pgtable_ent, type
	dc cvac, cur_\()\type\()p // Ensure any existing dirty
	dmb sy // lines are written back before
	ldr \type, [cur_\()\type\()p] // loading the entry
	tbz \type, #0, skip_\()\type // Skip invalid and
	tbnz \type, #11, skip_\()\type // non-global entries
	.endm

	.macro __idmap_kpti_put_pgtable_ent_ng, type
	orr \type, \type, #PTE_NG // Same bit for blocks and pages
	str \type, [cur_\()\type\()p] // Update the entry and ensure
	dmb sy // that it is visible to all
	dc civac, cur_\()\type\()p // CPUs.
	.endm

	/*
	* void __kpti_install_ng_mappings(int cpu, int num_cpus, phys_addr_t swapper)
	*
	* Called exactly once from stop_machine context by each CPU found during boot.
	*/
	__idmap_kpti_flag:
	.long 1
	ENTRY(idmap_kpti_install_ng_mappings)
	cpu .req w0
	num_cpus .req w1
	swapper_pa .req x2
	swapper_ttb .req x3
	flag_ptr .req x4
	cur_pgdp .req x5
	end_pgdp .req x6
	pgd .req x7
	cur_pudp .req x8
	end_pudp .req x9
	pud .req x10
	cur_pmdp .req x11
	end_pmdp .req x12
	pmd .req x13
	cur_ptep .req x14
	end_ptep .req x15
	pte .req x16

	mrs swapper_ttb, ttbr1_el1
	restore_ttbr1 swapper_ttb
	adr flag_ptr, __idmap_kpti_flag

	cbnz cpu, __idmap_kpti_secondary

	/* We're the boot CPU. Wait for the others to catch up */
	sevl
	1: wfe
	ldaxr w18, [flag_ptr]
	eor w18, w18, num_cpus
	cbnz w18, 1b

	/* We need to walk swapper, so turn off the MMU. */
	pre_disable_mmu_workaround
	mrs x18, sctlr_el1
	bic x18, x18, #SCTLR_ELx_M
	msr sctlr_el1, x18
	isb

	/* Everybody is enjoying the idmap, so we can rewrite swapper. */
	/* PGD */
	mov cur_pgdp, swapper_pa
	add end_pgdp, cur_pgdp, #(PTRS_PER_PGD * 8)
	do_pgd: __idmap_kpti_get_pgtable_ent pgd
	tbnz pgd, #1, walk_puds
	next_pgd:
	__idmap_kpti_put_pgtable_ent_ng pgd
	skip_pgd:
	add cur_pgdp, cur_pgdp, #8
	cmp cur_pgdp, end_pgdp
	b.ne do_pgd

	/* Publish the updated tables and nuke all the TLBs */
	dsb sy
	tlbi vmalle1is
	dsb ish
	isb

	/* We're done: fire up the MMU again */
	mrs x18, sctlr_el1
	orr x18, x18, #SCTLR_ELx_M
	msr sctlr_el1, x18
	isb

	/* Set the flag to zero to indicate that we're all done */
	str wzr, [flag_ptr]
	ret

	/* PUD */
	walk_puds:
	.if CONFIG_PGTABLE_LEVELS > 3
	pte_to_phys cur_pudp, pgd
	add end_pudp, cur_pudp, #(PTRS_PER_PUD * 8)
	do_pud: __idmap_kpti_get_pgtable_ent pud
	tbnz pud, #1, walk_pmds
	next_pud:
	__idmap_kpti_put_pgtable_ent_ng pud
	skip_pud:
	add cur_pudp, cur_pudp, 8
	cmp cur_pudp, end_pudp
	b.ne do_pud
	b next_pgd
	.else /* CONFIG_PGTABLE_LEVELS <= 3 */
	mov pud, pgd
	b walk_pmds
	next_pud:
	b next_pgd
	.endif

	/* PMD */
	walk_pmds:
	.if CONFIG_PGTABLE_LEVELS > 2
	pte_to_phys cur_pmdp, pud
	add end_pmdp, cur_pmdp, #(PTRS_PER_PMD * 8)
	do_pmd: __idmap_kpti_get_pgtable_ent pmd
	tbnz pmd, #1, walk_ptes
	next_pmd:
	__idmap_kpti_put_pgtable_ent_ng pmd
	skip_pmd:
	add cur_pmdp, cur_pmdp, #8
	cmp cur_pmdp, end_pmdp
	b.ne do_pmd
	b next_pud
	.else /* CONFIG_PGTABLE_LEVELS <= 2 */
	mov pmd, pud
	b walk_ptes
	next_pmd:
	b next_pud
	.endif

	/* PTE */
	walk_ptes:
	pte_to_phys cur_ptep, pmd
	add end_ptep, cur_ptep, #(PTRS_PER_PTE * 8)
	do_pte: __idmap_kpti_get_pgtable_ent pte
	__idmap_kpti_put_pgtable_ent_ng pte
	skip_pte:
	add cur_ptep, cur_ptep, #8
	cmp cur_ptep, end_ptep
	b.ne do_pte
	b next_pmd

	/* Secondary CPUs end up here */
	__idmap_kpti_secondary:
	/* Uninstall swapper before surgery begins */
	__idmap_cpu_set_reserved_ttbr1 x18, x17

	/* Increment the flag to let the boot CPU we're ready */
	1: ldxr w18, [flag_ptr]
	add w18, w18, #1
	stxr w17, w18, [flag_ptr]
	cbnz w17, 1b

	/* Wait for the boot CPU to finish messing around with swapper */
	sevl
	1: wfe
	ldxr w18, [flag_ptr]
	cbnz w18, 1b

	/* All done, act like nothing happened */
	offset_ttbr1 swapper_ttb
	msr ttbr1_el1, swapper_ttb
	isb
	ret

	.unreq cpu
	.unreq num_cpus
	.unreq swapper_pa
	.unreq swapper_ttb
	.unreq flag_ptr
	.unreq cur_pgdp
	.unreq end_pgdp
	.unreq pgd
	.unreq cur_pudp
	.unreq end_pudp
	.unreq pud
	.unreq cur_pmdp
	.unreq end_pmdp
	.unreq pmd
	.unreq cur_ptep
	.unreq end_ptep
	.unreq pte
	ENDPROC(idmap_kpti_install_ng_mappings)
	.popsection
	#endif

	/*
	* __cpu_setup
	*
	* Initialise the processor for turning the MMU on. Return in x0 the
	* value of the SCTLR_EL1 register.
	*/
	.pushsection ".idmap.text", "awx"
	ENTRY(__cpu_setup)
	tlbi vmalle1 // Invalidate local TLB
	dsb nsh

	mov x0, #3 << 20
	msr cpacr_el1, x0 // Enable FP/ASIMD
	mov x0, #1 << 12 // Reset mdscr_el1 and disable
	msr mdscr_el1, x0 // access to the DCC from EL0
	isb // Unmask debug exceptions now,
	enable_dbg // since this is per-cpu
	reset_pmuserenr_el0 x0 // Disable PMU access from EL0
	/*
	* Memory region attributes for LPAE:
	*
	* n = AttrIndx[2:0]
	* n MAIR
	* DEVICE_nGnRnE 000 00000000
	* DEVICE_nGnRE 001 00000100
	* DEVICE_GRE 010 00001100
	* NORMAL_NC 011 01000100
	* NORMAL 100 11111111
	* NORMAL_WT 101 10111011
	*/
	ldr x5, =MAIR(0x00, MT_DEVICE_nGnRnE) \| \
	MAIR(0x04, MT_DEVICE_nGnRE) \| \
	MAIR(0x0c, MT_DEVICE_GRE) \| \
	MAIR(0x44, MT_NORMAL_NC) \| \
	MAIR(0xff, MT_NORMAL) \| \
	MAIR(0xbb, MT_NORMAL_WT)
	msr mair_el1, x5
	/*
	* Prepare SCTLR
	*/
	mov_q x0, SCTLR_EL1_SET
	/*
	* Set/prepare TCR and TTBR. We use 512GB (39-bit) address range for
	* both user and kernel.
	*/
	ldr x10, =TCR_TxSZ(VA_BITS) \| TCR_CACHE_FLAGS \| TCR_SMP_FLAGS \| \
	TCR_TG_FLAGS \| TCR_KASLR_FLAGS \| TCR_ASID16 \| \
	TCR_TBI0 \| TCR_A1 \| TCR_KASAN_FLAGS
	tcr_clear_errata_bits x10, x9, x5

	#ifdef CONFIG_ARM64_USER_VA_BITS_52
	ldr_l x9, vabits_user
	sub x9, xzr, x9
	add x9, x9, #64
	#else
	ldr_l x9, idmap_t0sz
	#endif
	tcr_set_t0sz x10, x9

	/*
	* Set the IPS bits in TCR_EL1.
	*/
	tcr_compute_pa_size x10, #TCR_IPS_SHIFT, x5, x6
	#ifdef CONFIG_ARM64_HW_AFDBM
	/*
	* Enable hardware update of the Access Flags bit.
	* Hardware dirty bit management is enabled later,
	* via capabilities.
	*/
	mrs x9, ID_AA64MMFR1_EL1
	and x9, x9, #0xf
	cbz x9, 1f
	orr x10, x10, #TCR_HA // hardware Access flag update
	1:
	#endif /* CONFIG_ARM64_HW_AFDBM */
	msr tcr_el1, x10
	ret // return to head.S
	ENDPROC(__cpu_setup)