path: root/arch/arm26/boot/compressed/head.S

/*
 *  linux/arch/arm26/boot/compressed/head.S
 *
 *  Copyright (C) 1996-2002 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.
 */
#include <linux/linkage.h>

/*
 * Debugging stuff
 *
 * Note that these macros must not contain any code which is not
 * 100% relocatable.  Any attempt to do so will result in a crash.
 * Please select one of the following when turning on debugging.
 */

		.macro	kputc,val
		mov	r0, \val
		bl	putc
		.endm

		.macro	kphex,val,len
		mov	r0, \val
		mov	r1, #\len
		bl	phex
		.endm

		.macro	debug_reloc_start
		.endm

		.macro	debug_reloc_end
		.endm

		.section ".start", #alloc, #execinstr
/*
 * sort out different calling conventions
 */
		.align
start:
		.type	start,#function
		.rept	8
		mov	r0, r0
		.endr

		b	1f
		.word	0x016f2818		@ Magic numbers to help the loader
		.word	start			@ absolute load/run zImage address
		.word	_edata			@ zImage end address
1:		mov	r7, r1			@ save architecture ID
		mov	r8, #0			@ save r0
		teqp	pc, #0x0c000003		@ turn off interrupts

		.text
		adr	r0, LC0
		ldmia	r0, {r1, r2, r3, r4, r5, r6, ip, sp}
		subs	r0, r0, r1		@ calculate the delta offset

		teq	r0, #0			@ if delta is zero, we're
		beq	not_relocated		@ running at the address we
						@ were linked at.

		add	r2, r2, r0		@ different address, so we
		add	r3, r3, r0		@ need to fix up various
		add	r5, r5, r0		@ pointers.
		add	r6, r6, r0
		add	ip, ip, r0
		add	sp, sp, r0

1:		ldr	r1, [r6, #0]		@ relocate entries in the GOT
		add	r1, r1, r0		@ table.  This fixes up the
		str	r1, [r6], #4		@ C references.
		cmp	r6, ip
		blo	1b

not_relocated:	mov	r0, #0
1:		str	r0, [r2], #4		@ clear bss
		str	r0, [r2], #4
		str	r0, [r2], #4
		str	r0, [r2], #4
		cmp	r2, r3
		blo	1b

		bl	cache_on

		mov	r1, sp			@ malloc space above stack
		add	r2, sp, #0x10000	@ 64k max

/*
 * Check to see if we will overwrite ourselves.
 *   r4 = final kernel address
 *   r5 = start of this image
 *   r2 = end of malloc space (and therefore this image)
 * We basically want:
 *   r4 >= r2 -> OK
 *   r4 + image length <= r5 -> OK
 */
		cmp	r4, r2
		bhs	wont_overwrite
		add	r0, r4, #4096*1024	@ 4MB largest kernel size
		cmp	r0, r5
		bls	wont_overwrite

		mov	r5, r2			@ decompress after malloc space
		mov	r0, r5
		mov	r3, r7
		bl	decompress_kernel

		add	r0, r0, #127
		bic	r0, r0, #127		@ align the kernel length
/*
 * r0     = decompressed kernel length
 * r1-r3  = unused
 * r4     = kernel execution address
 * r5     = decompressed kernel start
 * r6     = processor ID
 * r7     = architecture ID
 * r8-r14 = unused
 */
		add	r1, r5, r0		@ end of decompressed kernel
		adr	r2, reloc_start
		ldr	r3, LC1
		add	r3, r2, r3
1:		ldmia	r2!, {r8 - r13}		@ copy relocation code
		stmia	r1!, {r8 - r13}
		ldmia	r2!, {r8 - r13}
		stmia	r1!, {r8 - r13}
		cmp	r2, r3
		blo	1b

		bl	cache_clean_flush
		add	pc, r5, r0		@ call relocation code

/*
 * We're not in danger of overwriting ourselves.  Do this the simple way.
 *
 * r4     = kernel execution address
 * r7     = architecture ID
 */
wont_overwrite:	mov	r0, r4
		mov	r3, r7
		bl	decompress_kernel
		b	call_kernel

		.type	LC0, #object
LC0:		.word	LC0			@ r1
		.word	__bss_start		@ r2
		.word	_end			@ r3
		.word	_load_addr		@ r4
		.word	_start			@ r5
		.word	_got_start		@ r6
		.word	_got_end		@ ip
		.word	user_stack+4096		@ sp
LC1:		.word	reloc_end - reloc_start
		.size	LC0, . - LC0

/*
 * Turn on the cache.  We need to setup some page tables so that we
 * can have both the I and D caches on.
 *
 * We place the page tables 16k down from the kernel execution address,
 * and we hope that nothing else is using it.  If we're using it, we
 * will go pop!
 *
 * On entry,
 *  r4 = kernel execution address
 *  r6 = processor ID
 *  r7 = architecture number
 *  r8 = run-time address of "start"
 * On exit,
 *  r1, r2, r3, r8, r9, r12 corrupted
 * This routine must preserve:
 *  r4, r5, r6, r7
 */
		.align	5
cache_on:	mov	r3, #8			@ cache_on function
		b	call_cache_fn

__setup_mmu:	sub	r3, r4, #16384		@ Page directory size
		bic	r3, r3, #0xff		@ Align the pointer
		bic	r3, r3, #0x3f00
/*
 * Initialise the page tables, turning on the cacheable and bufferable
 * bits for the RAM area only.
 */
		mov	r0, r3
		mov	r8, r0, lsr #18
		mov	r8, r8, lsl #18		@ start of RAM
		add	r9, r8, #0x10000000	@ a reasonable RAM size
		mov	r1, #0x12
		orr	r1, r1, #3 << 10
		add	r2, r3, #16384
1:		cmp	r1, r8			@ if virt > start of RAM
		orrhs	r1, r1, #0x0c		@ set cacheable, bufferable
		cmp	r1, r9			@ if virt > end of RAM
		bichs	r1, r1