memcpy.S

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */

#include <linux/export.h>
#include <asm/alternative-asm.h>
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/cpu.h>
#include <asm/regdef.h>
#include <asm/unwind_hints.h>

.section .noinstr.text, "ax"

SYM_FUNC_START(memcpy)
	/*
	 * Some CPUs support hardware unaligned access
	 */
	ALTERNATIVE	"b __memcpy_generic", \
			"b __memcpy_fast", CPU_FEATURE_UAL
SYM_FUNC_END(memcpy)
SYM_FUNC_ALIAS(__memcpy, memcpy)

EXPORT_SYMBOL(memcpy)
EXPORT_SYMBOL(__memcpy)

_ASM_NOKPROBE(memcpy)
_ASM_NOKPROBE(__memcpy)

/*
 * void *__memcpy_generic(void *dst, const void *src, size_t n)
 *
 * a0: dst
 * a1: src
 * a2: n
 */
SYM_FUNC_START(__memcpy_generic)
	move	a3, a0
	beqz	a2, 2f

1:	ld.b	t0, a1, 0
	st.b	t0, a0, 0
	addi.d	a0, a0, 1
	addi.d	a1, a1, 1
	addi.d	a2, a2, -1
	bgt	a2, zero, 1b

2:	move	a0, a3
	jr	ra
SYM_FUNC_END(__memcpy_generic)
_ASM_NOKPROBE(__memcpy_generic)

	.align	5
SYM_FUNC_START_NOALIGN(__memcpy_small)
	pcaddi	t0, 8
	slli.d	a2, a2, 5
	add.d	t0, t0, a2
	jr	t0

	.align	5
0:	jr	ra

	.align	5
1:	ld.b	t0, a1, 0
	st.b	t0, a0, 0
	jr	ra

	.align	5
2:	ld.h	t0, a1, 0
	st.h	t0, a0, 0
	jr	ra

	.align	5
3:	ld.h	t0, a1, 0
	ld.b	t1, a1, 2
	st.h	t0, a0, 0
	st.b	t1, a0, 2
	jr	ra

	.align	5
4:	ld.w	t0, a1, 0
	st.w	t0, a0, 0
	jr	ra

	.align	5
5:	ld.w	t0, a1, 0
	ld.b	t1, a1, 4
	st.w	t0, a0, 0
	st.b	t1, a0, 4
	jr	ra

	.align	5
6:	ld.w	t0, a1, 0
	ld.h	t1, a1, 4
	st.w	t0, a0, 0
	st.h	t1, a0, 4
	jr	ra

	.align	5
7:	ld.w	t0, a1, 0
	ld.w	t1, a1, 3
	st.w	t0, a0, 0
	st.w	t1, a0, 3
	jr	ra

	.align	5
8:	ld.d	t0, a1, 0
	st.d	t0, a0, 0
	jr	ra
SYM_FUNC_END(__memcpy_small)
_ASM_NOKPROBE(__memcpy_small)

/*
 * void *__memcpy_fast(void *dst, const void *src, size_t n)
 *
 * a0: dst
 * a1: src
 * a2: n
 */
SYM_FUNC_START(__memcpy_fast)
	sltui	t0, a2, 9
	bnez	t0, __memcpy_small

	add.d	a3, a1, a2
	add.d	a2, a0, a2
	ld.d	a6, a1, 0
	ld.d	a7, a3, -8

	/* align up destination address */
	andi	t1, a0, 7
	sub.d	t0, zero, t1
	addi.d	t0, t0, 8
	add.d	a1, a1, t0
	add.d	a5, a0, t0

	addi.d	a4, a3, -64
	bgeu	a1, a4, .Llt64

	/* copy 64 bytes at a time */
.Lloop64:
	ld.d	t0, a1, 0
	ld.d	t1, a1, 8
	ld.d	t2, a1, 16
	ld.d	t3, a1, 24
	ld.d	t4, a1, 32
	ld.d	t5, a1, 40
	ld.d	t6, a1, 48
	ld.d	t7, a1, 56
	addi.d	a1, a1, 64
	st.d	t0, a5, 0
	st.d	t1, a5, 8
	st.d	t2, a5, 16
	st.d	t3, a5, 24
	st.d	t4, a5, 32
	st.d	t5, a5, 40
	st.d	t6, a5, 48
	st.d	t7, a5, 56
	addi.d	a5, a5, 64
	bltu	a1, a4, .Lloop64

	/* copy the remaining bytes */
.Llt64:
	addi.d	a4, a3, -32
	bgeu	a1, a4, .Llt32
	ld.d	t0, a1, 0
	ld.d	t1, a1, 8
	ld.d	t2, a1, 16
	ld.d	t3, a1, 24
	addi.d	a1, a1, 32
	st.d	t0, a5, 0
	st.d	t1, a5, 8
	st.d	t2, a5, 16
	st.d	t3, a5, 24
	addi.d	a5, a5, 32

.Llt32:
	addi.d	a4, a3, -16
	bgeu	a1, a4, .Llt16
	ld.d	t0, a1, 0
	ld.d	t1, a1, 8
	addi.d	a1, a1, 16
	st.d	t0, a5, 0
	st.d	t1, a5, 8
	addi.d	a5, a5, 16

.Llt16:
	addi.d	a4, a3, -8
	bgeu	a1, a4, .Llt8
	ld.d	t0, a1, 0
	st.d	t0, a5, 0

.Llt8:
	st.d	a6, a0, 0
	st.d	a7, a2, -8

	/* return */
	jr	ra
SYM_FUNC_END(__memcpy_fast)
_ASM_NOKPROBE(__memcpy_fast)

STACK_FRAME_NON_STANDARD __memcpy_small