arch/arm64/include/asm/asm-uaccess.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_ASM_UACCESS_H
#define __ASM_ASM_UACCESS_H

#include <asm/alternative.h>
#include <asm/kernel-pgtable.h>
#include <asm/mmu.h>
#include <asm/sysreg.h>
#include <asm/assembler.h>

/*
 * User access enabling/disabling macros.
 */
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
	.macro	__uaccess_ttbr0_disable, tmp1
	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir
	bic	\tmp1, \tmp1, #TTBR_ASID_MASK
	sub	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE	// reserved_ttbr0 just before swapper_pg_dir
	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1
	isb
	add	\tmp1, \tmp1, #RESERVED_TTBR0_SIZE
	msr	ttbr1_el1, \tmp1		// set reserved ASID
	isb
	.endm

	.macro	__uaccess_ttbr0_enable, tmp1, tmp2
	get_current_task \tmp1
	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1
	mrs	\tmp2, ttbr1_el1
	extr    \tmp2, \tmp2, \tmp1, #48
	ror     \tmp2, \tmp2, #16
	msr	ttbr1_el1, \tmp2		// set the active ASID
	isb
	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1
	isb
	.endm

	.macro	uaccess_ttbr0_disable, tmp1, tmp2
alternative_if_not ARM64_HAS_PAN
	save_and_disable_irq \tmp2		// avoid preemption
	__uaccess_ttbr0_disable \tmp1
	restore_irq \tmp2
alternative_else_nop_endif
	.endm

	.macro	uaccess_ttbr0_enable, tmp1, tmp2, tmp3
alternative_if_not ARM64_HAS_PAN
	save_and_disable_irq \tmp3		// avoid preemption
	__uaccess_ttbr0_enable \tmp1, \tmp2
	restore_irq \tmp3
alternative_else_nop_endif
	.endm
#else
	.macro	uaccess_ttbr0_disable, tmp1, tmp2
	.endm

	.macro	uaccess_ttbr0_enable, tmp1, tmp2, tmp3
	.endm
#endif

#endif