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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/nios2/boot/compressed/head.S
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/*

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 * Copyright (C) 2009 Thomas Chou <[email protected]>

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 *

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 * Based on arch/nios2/kernel/head.S

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 *

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 * This file is subject to the terms and conditions of the GNU General Public

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 * License. See the file "COPYING" in the main directory of this archive

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 * for more details.

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 *

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 */

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/*

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 *  This code can be loaded anywhere, eg FLASH ROM as reset vector,

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 *  as long as output does not overlap it.

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 */

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#include <linux/linkage.h>

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#include <asm/cache.h>

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	.text

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	.set noat

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ENTRY(_start)

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	wrctl	status, r0		/* disable interrupt */

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	/* invalidate all instruction cache */

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	movia	r1, NIOS2_ICACHE_SIZE

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	movui	r2, NIOS2_ICACHE_LINE_SIZE

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1:	initi	r1

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	sub	r1, r1, r2

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	bgt	r1, r0, 1b

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	/* invalidate all data cache */

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	movia	r1, NIOS2_DCACHE_SIZE

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	movui	r2, NIOS2_DCACHE_LINE_SIZE

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1:	initd	0(r1)

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	sub	r1, r1, r2

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	bgt	r1, r0, 1b

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	nextpc	r1			/* Find out where we are */

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chkadr:

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	movia	r2, chkadr

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	beq	r1, r2, finish_move	/* We are running in correct address,

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					   done */

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	/* move code, r1: src, r2: dest, r3: last dest */

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	addi	r1, r1, (_start - chkadr)	/* Source */

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	movia	r2, _start		/* Destination */

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	movia	r3, __bss_start		/* End of copy */

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1:	ldw	r8, 0(r1)		/* load a word from [r1] */

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	stw	r8, 0(r2)		/* stort a word to dest [r2] */

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	addi	r1, r1, 4		/* inc the src addr */

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	addi	r2, r2, 4		/* inc the dest addr */

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	blt	r2, r3, 1b

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	/* flush the data cache after moving */

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	movia	r1, NIOS2_DCACHE_SIZE

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	movui	r2, NIOS2_DCACHE_LINE_SIZE

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1:	flushd	0(r1)

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	sub	r1, r1, r2

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	bgt	r1, r0, 1b

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	movia	r1, finish_move

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	jmp	r1			/* jmp to linked address */

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finish_move:

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	/* zero out the .bss segment (uninitialized common data) */

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	movia	r2, __bss_start		/* presume nothing is between */

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	movia	r1, _end		/* the .bss and _end. */

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1: 	stb	r0, 0(r2)

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	addi	r2, r2, 1

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	bne	r1, r2, 1b

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	/*

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	 * set up the stack pointer, some where higher than _end.

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	 * The stack space must be greater than 32K for decompress.

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	 */

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	movia	sp, 0x10000

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	add	sp, sp, r1

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	/* save args passed from u-boot, maybe */

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	addi	sp, sp, -16

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	stw	r4, 0(sp)

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	stw	r5, 4(sp)

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	stw	r6, 8(sp)

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	stw	r7, 12(sp)

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	/* decompress the kernel */

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	call	decompress_kernel

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	/* pass saved args to kernel */

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	ldw	r4, 0(sp)

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	ldw	r5, 4(sp)

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	ldw	r6, 8(sp)

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	ldw	r7, 12(sp)

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	/* flush all data cache after decompressing */

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	movia	r1, NIOS2_DCACHE_SIZE

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	movui	r2, NIOS2_DCACHE_LINE_SIZE

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1:	flushd	0(r1)

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	sub	r1, r1, r2

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	bgt	r1, r0, 1b

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	/* flush all instruction cache */

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	movia	r1, NIOS2_ICACHE_SIZE

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	movui	r2, NIOS2_ICACHE_LINE_SIZE

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1:	flushi	r1

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	sub	r1, r1, r2

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	bgt	r1, r0, 1b

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	flushp

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	/* jump to start real kernel */

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	movia	r1, (CONFIG_NIOS2_MEM_BASE | CONFIG_NIOS2_KERNEL_REGION_BASE)

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	jmp	r1

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	.balign 512

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fake_headers_as_bzImage:

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	.short	0

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	.ascii	"HdrS"

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	.short	0x0202

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	.short	0

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	.short	0

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	.byte	0x00, 0x10

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	.short	0

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	.byte	0

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	.byte	1

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	.byte	0x00, 0x80

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	.long	0

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	.long	0

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