uaccess-user.s

linux-2.6.15.6

/*
 *  linux/arch/arm26/lib/uaccess-user.S
 *
 *  Copyright (C) 1995, 1996,1997,1998 Russell King
 *
 * 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.
 *
 *  Routines to block copy data to/from user memory
 *   These are highly optimised both for the 4k page size
 *   and for various alignments.
 */
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/errno.h>
#include <asm/page.h>

		.text

//FIXME - surely this can be done in C not asm, removing the problem of keeping C and asm in sync? (this is a struct uaccess_t)
                .globl  uaccess_user
uaccess_user:
                .word   uaccess_user_put_byte
                .word   uaccess_user_get_byte
                .word   uaccess_user_put_half
                .word   uaccess_user_get_half
                .word   uaccess_user_put_word
                .word   uaccess_user_get_word
		.word   uaccess_user_put_dword
                .word   uaccess_user_copy_from_user
                .word   uaccess_user_copy_to_user
                .word   uaccess_user_clear_user
                .word   uaccess_user_strncpy_from_user
                .word   uaccess_user_strnlen_user


@ In : r0 = x, r1 = addr, r2 = error
@ Out: r2 = error
uaccess_user_put_byte:
                stmfd   sp!, {lr}
USER(           strbt   r0, [r1])
                ldmfd   sp!, {pc}^

@ In : r0 = x, r1 = addr, r2 = error
@ Out: r2 = error
uaccess_user_put_half:
                stmfd   sp!, {lr}
USER(           strbt   r0, [r1], #1)
                mov     r0, r0, lsr #8
USER(           strbt   r0, [r1])
                ldmfd   sp!, {pc}^

@ In : r0 = x, r1 = addr, r2 = error
@ Out: r2 = error
uaccess_user_put_word:
                stmfd   sp!, {lr}
USER(           strt    r0, [r1])
                ldmfd   sp!, {pc}^

@ In : r0 = x, r1 = addr, r2 = error
@ Out: r2 = error
uaccess_user_put_dword:
                stmfd   sp!, {lr}
USER(           strt    r0, [r1], #4)
USER(           strt    r0, [r1], #0)
                ldmfd   sp!, {pc}^

9001:           mov     r2, #-EFAULT
                ldmfd   sp!, {pc}^


@ In : r0 = addr, r1 = error
@ Out: r0 = x, r1 = error
uaccess_user_get_byte:
                stmfd   sp!, {lr}
USER(           ldrbt   r0, [r0])
                ldmfd   sp!, {pc}^

@ In : r0 = addr, r1 = error
@ Out: r0 = x, r1 = error
uaccess_user_get_half:
                stmfd   sp!, {lr}
USER(           ldrt    r0, [r0])
                mov     r0, r0, lsl #16
                mov     r0, r0, lsr #16
                ldmfd   sp!, {pc}^

@ In : r0 = addr, r1 = error
@ Out: r0 = x, r1 = error
uaccess_user_get_word:
                stmfd   sp!, {lr}
USER(           ldrt    r0, [r0])
                ldmfd   sp!, {pc}^

9001:           mov     r1, #-EFAULT
                ldmfd   sp!, {pc}^

/* Prototype: int uaccess_user_copy_to_user(void *to, const char *from, size_t n)
 * Purpose  : copy a block to user memory from kernel memory
 * Params   : to   - user memory
 *          : from - kernel memory
 *          : n    - number of bytes to copy
 * Returns  : Number of bytes NOT copied.
 */

.c2u_dest_not_aligned:
		rsb	ip, ip, #4
		cmp	ip, #2
		ldrb	r3, [r1], #1
USER(		strbt	r3, [r0], #1)			@ May fault
		ldrgeb	r3, [r1], #1
USER(		strgebt	r3, [r0], #1)			@ May fault
		ldrgtb	r3, [r1], #1
USER(		strgtbt	r3, [r0], #1)			@ May fault
		sub	r2, r2, ip
		b	.c2u_dest_aligned

ENTRY(uaccess_user_copy_to_user)
		stmfd	sp!, {r2, r4 - r7, lr}
		cmp	r2, #4
		blt	.c2u_not_enough
		ands	ip, r0, #3
		bne	.c2u_dest_not_aligned
.c2u_dest_aligned:

		ands	ip, r1, #3
		bne	.c2u_src_not_aligned
/*
 * Seeing as there has to be at least 8 bytes to copy, we can
 * copy one word, and force a user-mode page fault...
 */

.c2u_0fupi:	subs	r2, r2, #4
		addmi	ip, r2, #4
		bmi	.c2u_0nowords
		ldr	r3, [r1], #4
USER(		strt	r3, [r0], #4)			@ May fault
		mov	ip, r0, lsl #32 - PAGE_SHIFT	@ On each page, use a ld/st??t instruction
		rsb	ip, ip, #0
		movs	ip, ip, lsr #32 - PAGE_SHIFT
		beq	.c2u_0fupi
/*
 * ip = max no. of bytes to copy before needing another "strt" insn
 */
		cmp	r2, ip
		movlt	ip, r2
		sub	r2, r2, ip
		subs	ip, ip, #32
		blt	.c2u_0rem8lp

.c2u_0cpy8lp:	ldmia	r1!, {r3 - r6}
		stmia	r0!, {r3 - r6}			@ Shouldnt fault
		ldmia	r1!, {r3 - r6}
		stmia	r0!, {r3 - r6}			@ Shouldnt fault
		subs	ip, ip, #32
		bpl	.c2u_0cpy8lp
.c2u_0rem8lp:	cmn	ip, #16
		ldmgeia	r1!, {r3 - r6}
		stmgeia	r0!, {r3 - r6}			@ Shouldnt fault
		tst	ip, #8
		ldmneia	r1!, {r3 - r4}
		stmneia	r0!, {r3 - r4}			@ Shouldnt fault
		tst	ip, #4
		ldrne	r3, [r1], #4
		strnet	r3, [r0], #4			@ Shouldnt fault
		ands	ip, ip, #3
		beq	.c2u_0fupi
.c2u_0nowords:	teq	ip, #0
		beq	.c2u_finished
.c2u_nowords:	cmp	ip, #2
		ldrb	r3, [r1], #1
USER(		strbt	r3, [r0], #1)			@ May fault
		ldrgeb	r3, [r1], #1
USER(		strgebt	r3, [r0], #1)			@ May fault
		ldrgtb	r3, [r1], #1
USER(		strgtbt	r3, [r0], #1)			@ May fault
		b	.c2u_finished

.c2u_not_enough:
		movs	ip, r2
		bne	.c2u_nowords
.c2u_finished:	mov	r0, #0
		LOADREGS(fd,sp!,{r2, r4 - r7, pc})

.c2u_src_not_aligned:
		bic	r1, r1, #3
		ldr	r7, [r1], #4
		cmp	ip, #2
		bgt	.c2u_3fupi
		beq	.c2u_2fupi
.c2u_1fupi:	subs	r2, r2, #4
		addmi	ip, r2, #4
		bmi	.c2u_1nowords
		mov	r3, r7, pull #8
		ldr	r7, [r1], #4
		orr	r3, r3, r7, push #24
USER(		strt	r3, [r0], #4)			@ May fault
		mov	ip, r0, lsl #32 - PAGE_SHIFT
		rsb	ip, ip, #0
		movs	ip, ip, lsr #32 - PAGE_SHIFT
		beq	.c2u_1fupi
		cmp	r2, ip
		movlt	ip, r2
		sub	r2, r2, ip
		subs	ip, ip, #16
		blt	.c2u_1rem8lp

.c2u_1cpy8lp:	mov	r3, r7, pull #8
		ldmia	r1!, {r4 - r7}
		orr	r3, r3, r4, push #24
		mov	r4, r4, pull #8
		orr	r4, r4, r5, push #24
		mov	r5, r5, pull #8
		orr	r5, r5, r6, push #24
		mov	r6, r6, pull #8
		orr	r6, r6, r7, push #24
		stmia	r0!, {r3 - r6}			@ Shouldnt fault
		subs	ip, ip, #16
		bpl	.c2u_1cpy8lp
.c2u_1rem8lp:	tst	ip, #8
		movne	r3, r7, pull #8
		ldmneia	r1!, {r4, r7}
		orrne	r3, r3, r4, push #24
		movne	r4, r4, pull #8
		orrne	r4, r4, r7, push #24
		stmneia	r0!, {r3 - r4}			@ Shouldnt fault
		tst	ip, #4
		movne	r3, r7, pull #8
		ldrne	r7, [r1], #4
		orrne	r3, r3, r7, push #24
		strnet	r3, [r0], #4			@ Shouldnt fault
		ands	ip, ip, #3
		beq	.c2u_1fupi
.c2u_1nowords:	mov	r3, r7, lsr #byte(1)
		teq	ip, #0
		beq	.c2u_finished
		cmp	ip, #2
USER(		strbt	r3, [r0], #1)			@ May fault
		movge	r3, r7, lsr #byte(2)
USER(		strgebt	r3, [r0], #1)			@ May fault
		movgt	r3, r7, lsr #byte(3)
USER(		strgtbt	r3, [r0], #1)			@ May fault
		b	.c2u_finished

.c2u_2fupi:	subs	r2, r2, #4
		addmi	ip, r2, #4
		bmi	.c2u_2nowords
		mov	r3, r7, pull #16
		ldr	r7, [r1], #4
		orr	r3, r3, r7, push #16
USER(		strt	r3, [r0], #4)			@ May fault
		mov	ip, r0, lsl #32 - PAGE_SHIFT
		rsb	ip, ip, #0
		movs	ip, ip, lsr #32 - PAGE_SHIFT
		beq	.c2u_2fupi
		cmp	r2, ip
		movlt	ip, r2
		sub	r2, r2, ip
		subs	ip, ip, #16
		blt	.c2u_2rem8lp

.c2u_2cpy8lp:	mov	r3, r7, pull #16
		ldmia	r1!, {r4 - r7}
		orr	r3, r3, r4, push #16
		mov	r4, r4, pull #16
		orr	r4, r4, r5, push #16
		mov	r5, r5, pull #16
		orr	r5, r5, r6, push #16
		mov	r6, r6, pull #16
		orr	r6, r6, r7, push #16
		stmia	r0!, {r3 - r6}			@ Shouldnt fault
		subs	ip, ip, #16
		bpl	.c2u_2cpy8lp
.c2u_2rem8lp:	tst	ip, #8
		movne	r3, r7, pull #16
		ldmneia	r1!, {r4, r7}
		orrne	r3, r3, r4, push #16
		movne	r4, r4, pull #16
		orrne	r4, r4, r7, push #16
		stmneia	r0!, {r3 - r4}			@ Shouldnt fault
		tst	ip, #4
		movne	r3, r7, pull #16
		ldrne	r7, [r1], #4
		orrne	r3, r3, r7, push #16
		strnet	r3, [r0], #4			@ Shouldnt fault
		ands	ip, ip, #3
		beq	.c2u_2fupi
.c2u_2nowords:	mov	r3, r7, lsr #byte(2)
		teq	ip, #0
		beq	.c2u_finished
		cmp	ip, #2
USER(		strbt	r3, [r0], #1)			@ May fault
		movge	r3, r7, lsr #byte(3)
USER(		strgebt	r3, [r0], #1)			@ May fault
		ldrgtb	r3, [r1], #0
USER(		strgtbt	r3, [r0], #1)			@ May fault
		b	.c2u_finished

.c2u_3fupi:	subs	r2, r2, #4
		addmi	ip, r2, #4
		bmi	.c2u_3nowords
		mov	r3, r7, pull #24
		ldr	r7, [r1], #4
		orr	r3, r3, r7, push #8
USER(		strt	r3, [r0], #4)			@ May fault
		mov	ip, r0, lsl #32 - PAGE_SHIFT
		rsb	ip, ip, #0
		movs	ip, ip, lsr #32 - PAGE_SHIFT
		beq	.c2u_3fupi
		cmp	r2, ip
		movlt	ip, r2
		sub	r2, r2, ip
		subs	ip, ip, #16
		blt	.c2u_3rem8lp

.c2u_3cpy8lp:	mov	r3, r7, pull #24
		ldmia	r1!, {r4 - r7}
		orr	r3, r3, r4, push #8
		mov	r4, r4, pull #24
		orr	r4, r4, r5, push #8
		mov	r5, r5, pull #24
		orr	r5, r5, r6, push #8
		mov	r6, r6, pull #24
		orr	r6, r6, r7, push #8
		stmia	r0!, {r3 - r6}			@ Shouldnt fault
		subs	ip, ip, #16
		bpl	.c2u_3cpy8lp
.c2u_3rem8lp:	tst	ip, #8
		movne	r3, r7, pull #24
		ldmneia	r1!, {r4, r7}
		orrne	r3, r3, r4, push #8
		movne	r4, r4, pull #24
		orrne	r4, r4, r7, push #8
		stmneia	r0!, {r3 - r4}			@ Shouldnt fault
		tst	ip, #4
		movne	r3, r7, pull #24
		ldrne	r7, [r1], #4
		orrne	r3, r3, r7, push #8
		strnet	r3, [r0], #4			@ Shouldnt fault
		ands	ip, ip, #3
		beq	.c2u_3fupi
.c2u_3nowords:	mov	r3, r7, lsr #byte(3)
		teq	ip, #0
		beq	.c2u_finished
		cmp	ip, #2
USER(		strbt	r3, [r0], #1)			@ May fault
		ldrgeb	r3, [r1], #1
USER(		strgebt	r3, [r0], #1)			@ May fault
		ldrgtb	r3, [r1], #0
USER(		strgtbt	r3, [r0], #1)			@ May fault
		b	.c2u_finished

		.section .fixup,"ax"
		.align	0
9001:		LOADREGS(fd,sp!, {r0, r4 - r7, pc})
		.previous

/* Prototype: unsigned long uaccess_user_copy_from_user(void *to,const void *from,unsigned long n);
 * Purpose  : copy a block from user memory to kernel memory