xref: /kernel/linux/linux-5.10/arch/arm/lib/getuser.S

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 *  linux/arch/arm/lib/getuser.S
 *
 *  Copyright (C) 2001 Russell King
 *
 *  Idea from x86 version, (C) Copyright 1998 Linus Torvalds
 *
 * These functions have a non-standard call interface to make them more
 * efficient, especially as they return an error value in addition to
 * the "real" return value.
 *
 * __get_user_X
 *
 * Inputs:	r0 contains the address
 *		r1 contains the address limit, which must be preserved
 * Outputs:	r0 is the error code
 *		r2, r3 contains the zero-extended value
 *		lr corrupted
 *
 * No other registers must be altered.  (see <asm/uaccess.h>
 * for specific ASM register usage).
 *
 * Note that ADDR_LIMIT is either 0 or 0xc0000000.
 * Note also that it is intended that __get_user_bad is not global.
 */
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/extable.h>
#include <asm/domain.h>

ENTRY(__get_user_1)
	check_uaccess r0, 1, r1, r2, __get_user_bad
1: TUSER(ldrb)	r2, [r0]
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_1)
_ASM_NOKPROBE(__get_user_1)

ENTRY(__get_user_2)
	check_uaccess r0, 2, r1, r2, __get_user_bad
#if __LINUX_ARM_ARCH__ >= 6

2: TUSER(ldrh)	r2, [r0]

#else

#ifdef CONFIG_CPU_USE_DOMAINS
rb	.req	ip
2:	ldrbt	r2, [r0], #1
3:	ldrbt	rb, [r0], #0
#else
rb	.req	r0
2:	ldrb	r2, [r0]
3:	ldrb	rb, [r0, #1]
#endif
#ifndef __ARMEB__
	orr	r2, r2, rb, lsl #8
#else
	orr	r2, rb, r2, lsl #8
#endif

#endif /* __LINUX_ARM_ARCH__ >= 6 */

	mov	r0, #0
	ret	lr
ENDPROC(__get_user_2)
_ASM_NOKPROBE(__get_user_2)

ENTRY(__get_user_4)
	check_uaccess r0, 4, r1, r2, __get_user_bad
4: TUSER(ldr)	r2, [r0]
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_4)
_ASM_NOKPROBE(__get_user_4)

ENTRY(__get_user_8)
	check_uaccess r0, 8, r1, r2, __get_user_bad8
#ifdef CONFIG_THUMB2_KERNEL
5: TUSER(ldr)	r2, [r0]
6: TUSER(ldr)	r3, [r0, #4]
#else
5: TUSER(ldr)	r2, [r0], #4
6: TUSER(ldr)	r3, [r0]
#endif
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_8)
_ASM_NOKPROBE(__get_user_8)

#ifdef __ARMEB__
ENTRY(__get_user_32t_8)
	check_uaccess r0, 8, r1, r2, __get_user_bad
#ifdef CONFIG_CPU_USE_DOMAINS
	add	r0, r0, #4
7:	ldrt	r2, [r0]
#else
7:	ldr	r2, [r0, #4]
#endif
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_32t_8)
_ASM_NOKPROBE(__get_user_32t_8)

ENTRY(__get_user_64t_1)
	check_uaccess r0, 1, r1, r2, __get_user_bad8
8: TUSER(ldrb)	r3, [r0]
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_64t_1)
_ASM_NOKPROBE(__get_user_64t_1)

ENTRY(__get_user_64t_2)
	check_uaccess r0, 2, r1, r2, __get_user_bad8
#ifdef CONFIG_CPU_USE_DOMAINS
rb	.req	ip
9:	ldrbt	r3, [r0], #1
10:	ldrbt	rb, [r0], #0
#else
rb	.req	r0
9:	ldrb	r3, [r0]
10:	ldrb	rb, [r0, #1]
#endif
	orr	r3, rb, r3, lsl #8
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_64t_2)
_ASM_NOKPROBE(__get_user_64t_2)

ENTRY(__get_user_64t_4)
	check_uaccess r0, 4, r1, r2, __get_user_bad8
11: TUSER(ldr)	r3, [r0]
	mov	r0, #0
	ret	lr
ENDPROC(__get_user_64t_4)
_ASM_NOKPROBE(__get_user_64t_4)
#endif

__get_user_bad8:
	mov	r3, #0
__get_user_bad:
	mov	r2, #0
	mov	r0, #-EFAULT
	ret	lr
ENDPROC(__get_user_bad)
ENDPROC(__get_user_bad8)
_ASM_NOKPROBE(__get_user_bad)
_ASM_NOKPROBE(__get_user_bad8)

.pushsection __ex_table, "a"
	ex_entry	1b, __get_user_bad
	ex_entry	2b, __get_user_bad
#if __LINUX_ARM_ARCH__ < 6
	ex_entry	3b, __get_user_bad
#endif
	ex_entry	4b, __get_user_bad
	ex_entry	5b, __get_user_bad8
	ex_entry	6b, __get_user_bad8
#ifdef __ARMEB__
	ex_entry	7b, __get_user_bad
	ex_entry	8b, __get_user_bad8
	ex_entry	9b, __get_user_bad8
	ex_entry	10b, __get_user_bad8
	ex_entry	11b, __get_user_bad8
#endif