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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/arm64/include/asm/asm-uaccess.h
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/* SPDX-License-Identifier: GPL-2.0 */

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#ifndef __ASM_ASM_UACCESS_H

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#define __ASM_ASM_UACCESS_H

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#include <asm/alternative-macros.h>

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#include <asm/asm-extable.h>

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#include <asm/assembler.h>

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#include <asm/kernel-pgtable.h>

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#include <asm/mmu.h>

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#include <asm/sysreg.h>

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/*

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 * User access enabling/disabling macros.

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 */

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#ifdef CONFIG_ARM64_SW_TTBR0_PAN

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	.macro	__uaccess_ttbr0_disable, tmp1

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	mrs	\tmp1, ttbr1_el1			// swapper_pg_dir

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	bic	\tmp1, \tmp1, #TTBR_ASID_MASK

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	sub	\tmp1, \tmp1, #RESERVED_SWAPPER_OFFSET	// reserved_pg_dir

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	msr	ttbr0_el1, \tmp1			// set reserved TTBR0_EL1

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	add	\tmp1, \tmp1, #RESERVED_SWAPPER_OFFSET

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	msr	ttbr1_el1, \tmp1		// set reserved ASID

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	isb

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	.endm

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	.macro	__uaccess_ttbr0_enable, tmp1, tmp2

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	get_current_task \tmp1

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	ldr	\tmp1, [\tmp1, #TSK_TI_TTBR0]	// load saved TTBR0_EL1

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	mrs	\tmp2, ttbr1_el1

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	extr    \tmp2, \tmp2, \tmp1, #48

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	ror     \tmp2, \tmp2, #16

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	msr	ttbr1_el1, \tmp2		// set the active ASID

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	msr	ttbr0_el1, \tmp1		// set the non-PAN TTBR0_EL1

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	isb

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	.endm

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	.macro	uaccess_ttbr0_disable, tmp1, tmp2

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alternative_if_not ARM64_HAS_PAN

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	save_and_disable_irq \tmp2		// avoid preemption

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	__uaccess_ttbr0_disable \tmp1

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	restore_irq \tmp2

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alternative_else_nop_endif

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	.endm

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	.macro	uaccess_ttbr0_enable, tmp1, tmp2, tmp3

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alternative_if_not ARM64_HAS_PAN

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	save_and_disable_irq \tmp3		// avoid preemption

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	__uaccess_ttbr0_enable \tmp1, \tmp2

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	restore_irq \tmp3

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alternative_else_nop_endif

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	.endm

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#else

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	.macro	uaccess_ttbr0_disable, tmp1, tmp2

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	.endm

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	.macro	uaccess_ttbr0_enable, tmp1, tmp2, tmp3

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	.endm

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#endif

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#define USER(l, x...)				\

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9999:	x;					\

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	_asm_extable_uaccess	9999b, l

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#define USER_CPY(l, uaccess_is_write, x...)	\

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9999:	x;					\

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	_asm_extable_uaccess_cpy 9999b, l, uaccess_is_write

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/*

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 * Generate the assembly for LDTR/STTR with exception table entries.

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 * This is complicated as there is no post-increment or pair versions of the

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 * unprivileged instructions, and USER() only works for single instructions.

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 */

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	.macro user_ldp l, reg1, reg2, addr, post_inc

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8888:		ldtr	\reg1, [\addr];

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8889:		ldtr	\reg2, [\addr, #8];

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		add	\addr, \addr, \post_inc;

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		_asm_extable_uaccess	8888b, \l;

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		_asm_extable_uaccess	8889b, \l;

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	.endm

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	.macro user_stp l, reg1, reg2, addr, post_inc

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8888:		sttr	\reg1, [\addr];

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8889:		sttr	\reg2, [\addr, #8];

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		add	\addr, \addr, \post_inc;

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		_asm_extable_uaccess	8888b,\l;

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		_asm_extable_uaccess	8889b,\l;

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	.endm

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	.macro user_ldst l, inst, reg, addr, post_inc

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8888:		\inst		\reg, [\addr];

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		add		\addr, \addr, \post_inc;

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		_asm_extable_uaccess	8888b, \l;

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	.endm

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#endif

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