[linux-2.6-block.git] / arch / x86 / boot / compressed / head_32.S

/*
 *  linux/boot/head.S
 *
 *  Copyright (C) 1991, 1992, 1993  Linus Torvalds
 */

/*
 *  head.S contains the 32-bit startup code.
 *
 * NOTE!!! Startup happens at absolute address 0x00001000, which is also where
 * the page directory will exist. The startup code will be overwritten by
 * the page directory. [According to comments etc elsewhere on a compressed
 * kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
 *
 * Page 0 is deliberately kept safe, since System Management Mode code in 
 * laptops may need to access the BIOS data stored there.  This is also
 * useful for future device drivers that either access the BIOS via VM86 
 * mode.
 */

/*
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 */
.text

#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page.h>
#include <asm/boot.h>
#include <asm/asm-offsets.h>

.section ".text.head","ax",@progbits
	.globl startup_32

startup_32:
	cld
	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
	 * us to not reload segments */
	testb $(1<<6), BP_loadflags(%esi)
	jnz 1f

	cli
	movl $(__BOOT_DS),%eax
	movl %eax,%ds
	movl %eax,%es
	movl %eax,%fs
	movl %eax,%gs
	movl %eax,%ss
1:

/* Calculate the delta between where we were compiled to run
 * at and where we were actually loaded at.  This can only be done
 * with a short local call on x86.  Nothing  else will tell us what
 * address we are running at.  The reserved chunk of the real-mode
 * data at 0x1e4 (defined as a scratch field) are used as the stack
 * for this calculation. Only 4 bytes are needed.
 */
	leal (0x1e4+4)(%esi), %esp
	call 1f
1:	popl %ebp
	subl $1b, %ebp

/* %ebp contains the address we are loaded at by the boot loader and %ebx
 * contains the address where we should move the kernel image temporarily
 * for safe in-place decompression.
 */

#ifdef CONFIG_RELOCATABLE
	movl 	%ebp, %ebx
	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
	andl    $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
#else
	movl $LOAD_PHYSICAL_ADDR, %ebx
#endif

	/* Replace the compressed data size with the uncompressed size */
	subl input_len(%ebp), %ebx
	movl output_len(%ebp), %eax
	addl %eax, %ebx
	/* Add 8 bytes for every 32K input block */
	shrl $12, %eax
	addl %eax, %ebx
	/* Add 32K + 18 bytes of extra slack */
	addl $(32768 + 18), %ebx
	/* Align on a 4K boundary */
	addl $4095, %ebx
	andl $~4095, %ebx

/* Copy the compressed kernel to the end of our buffer
 * where decompression in place becomes safe.
 */
	pushl %esi
	leal _end(%ebp), %esi
	leal _end(%ebx), %edi
	movl $(_end - startup_32), %ecx
	std
	rep
	movsb
	cld
	popl %esi

/* Compute the kernel start address.
 */
#ifdef CONFIG_RELOCATABLE
	addl    $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
	andl    $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp
#else
	movl	$LOAD_PHYSICAL_ADDR, %ebp
#endif

/*
 * Jump to the relocated address.
 */
	leal relocated(%ebx), %eax
	jmp *%eax
.section ".text"
relocated:

/*
 * Clear BSS
 */
	xorl %eax,%eax
	leal _edata(%ebx),%edi
	leal _end(%ebx), %ecx
	subl %edi,%ecx
	cld
	rep
	stosb

/*
 * Setup the stack for the decompressor
 */
	leal boot_stack_end(%ebx), %esp

/*
 * Do the decompression, and jump to the new kernel..
 */
	movl output_len(%ebx), %eax
	pushl %eax
	pushl %ebp	# output address
	movl input_len(%ebx), %eax
	pushl %eax	# input_len
	leal input_data(%ebx), %eax
	pushl %eax	# input_data
	leal boot_heap(%ebx), %eax
	pushl %eax	# heap area as third argument
	pushl %esi	# real mode pointer as second arg
	call decompress_kernel
	addl $20, %esp
	popl %ecx

#if CONFIG_RELOCATABLE
/* Find the address of the relocations.
 */
	movl %ebp, %edi
	addl %ecx, %edi

/* Calculate the delta between where vmlinux was compiled to run
 * and where it was actually loaded.
 */
	movl %ebp, %ebx
	subl $LOAD_PHYSICAL_ADDR, %ebx
	jz   2f		/* Nothing to be done if loaded at compiled addr. */
/*
 * Process relocations.
 */

1:	subl $4, %edi
	movl 0(%edi), %ecx
	testl %ecx, %ecx
	jz 2f
	addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
	jmp 1b
2:
#endif

/*
 * Jump to the decompressed kernel.
 */
	xorl %ebx,%ebx
	jmp *%ebp

.bss
/* Stack and heap for uncompression */
.balign 4
boot_heap:
	.fill BOOT_HEAP_SIZE, 1, 0
boot_stack:
	.fill BOOT_STACK_SIZE, 1, 0
boot_stack_end:
Commit	Line	Data
1da177e4 LT	1	/*
	2	* linux/boot/head.S
	3	*
	4	* Copyright (C) 1991, 1992, 1993 Linus Torvalds
	5	*/
	6
	7	/*
	8	* head.S contains the 32-bit startup code.
	9	*
	10	* NOTE!!! Startup happens at absolute address 0x00001000, which is also where
	11	* the page directory will exist. The startup code will be overwritten by
	12	* the page directory. [According to comments etc elsewhere on a compressed
	13	* kernel it will end up at 0x1000 + 1Mb I hope so as I assume this. - AC]
	14	*
	15	* Page 0 is deliberately kept safe, since System Management Mode code in
	16	* laptops may need to access the BIOS data stored there. This is also
	17	* useful for future device drivers that either access the BIOS via VM86
	18	* mode.
	19	*/
	20
	21	/*
	22	* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
	23	*/
	24	.text
	25
	26	#include <linux/linkage.h>
	27	#include <asm/segment.h>
968de4f0	28	#include <asm/page.h>
e69f202d	29	#include <asm/boot.h>
a24e7851	30	#include <asm/asm-offsets.h>
1da177e4	31
c6b33cc4	32	.section ".text.head","ax",@progbits
1da177e4	33	.globl startup_32
968de4f0	34
1da177e4	35	startup_32:
bd53147d	36	cld
a24e7851 RR	37	/* test KEEP_SEGMENTS flag to see if the bootloader is asking
	38	* us to not reload segments */
	39	testb $(1<<6), BP_loadflags(%esi)
bd53147d	40	jnz 1f
a24e7851	41
bd53147d	42	cli
1da177e4 LT	43	movl $(__BOOT_DS),%eax
	44	movl %eax,%ds
	45	movl %eax,%es
	46	movl %eax,%fs
	47	movl %eax,%gs
968de4f0	48	movl %eax,%ss
bd53147d	49	1:
a24e7851	50
968de4f0 EB	51	/* Calculate the delta between where we were compiled to run
	52	* at and where we were actually loaded at. This can only be done
	53	* with a short local call on x86. Nothing else will tell us what
	54	* address we are running at. The reserved chunk of the real-mode
85414b69 PA	55	* data at 0x1e4 (defined as a scratch field) are used as the stack
85414b69 PA	56	* for this calculation. Only 4 bytes are needed.
968de4f0	57	*/
85414b69	58	leal (0x1e4+4)(%esi), %esp
968de4f0 EB	59	call 1f
	60	1: popl %ebp
	61	subl $1b, %ebp
	62
e69f202d VG	63	/* %ebp contains the address we are loaded at by the boot loader and %ebx
	64	* contains the address where we should move the kernel image temporarily
	65	* for safe in-place decompression.
968de4f0	66	*/
e69f202d	67
968de4f0	68	#ifdef CONFIG_RELOCATABLE
e69f202d VG	69	movl %ebp, %ebx
	70	addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
	71	andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
968de4f0	72	#else
e69f202d	73	movl $LOAD_PHYSICAL_ADDR, %ebx
968de4f0 EB	74	#endif
	75
	76	/* Replace the compressed data size with the uncompressed size */
	77	subl input_len(%ebp), %ebx
	78	movl output_len(%ebp), %eax
	79	addl %eax, %ebx
	80	/* Add 8 bytes for every 32K input block */
	81	shrl $12, %eax
	82	addl %eax, %ebx
	83	/* Add 32K + 18 bytes of extra slack */
	84	addl $(32768 + 18), %ebx
	85	/* Align on a 4K boundary */
	86	addl $4095, %ebx
	87	andl $~4095, %ebx
	88
	89	/* Copy the compressed kernel to the end of our buffer
	90	* where decompression in place becomes safe.
	91	*/
	92	pushl %esi
	93	leal _end(%ebp), %esi
	94	leal _end(%ebx), %edi
	95	movl $(_end - startup_32), %ecx
	96	std
	97	rep
	98	movsb
	99	cld
	100	popl %esi
	101
	102	/* Compute the kernel start address.
	103	*/
	104	#ifdef CONFIG_RELOCATABLE
e69f202d VG	105	addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
e69f202d VG	106	andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp
968de4f0	107	#else
e69f202d	108	movl $LOAD_PHYSICAL_ADDR, %ebp
968de4f0	109	#endif
1da177e4 LT	110
1da177e4 LT	111	/*
968de4f0	112	* Jump to the relocated address.
1da177e4	113	*/
968de4f0 EB	114	leal relocated(%ebx), %eax
	115	jmp *%eax
	116	.section ".text"
	117	relocated:
	118
1da177e4 LT	119	/*
	120	* Clear BSS
	121	*/
	122	xorl %eax,%eax
968de4f0 EB	123	leal _edata(%ebx),%edi
968de4f0 EB	124	leal _end(%ebx), %ecx
1da177e4 LT	125	subl %edi,%ecx
	126	cld
	127	rep
	128	stosb
968de4f0 EB	129
	130	/*
	131	* Setup the stack for the decompressor
	132	*/
7c539764	133	leal boot_stack_end(%ebx), %esp
968de4f0	134
1da177e4 LT	135	/*
	136	* Do the decompression, and jump to the new kernel..
	137	*/
968de4f0 EB	138	movl output_len(%ebx), %eax
	139	pushl %eax
	140	pushl %ebp # output address
	141	movl input_len(%ebx), %eax
	142	pushl %eax # input_len
	143	leal input_data(%ebx), %eax
	144	pushl %eax # input_data
7c539764 AH	145	leal boot_heap(%ebx), %eax
7c539764 AH	146	pushl %eax # heap area as third argument
1da177e4	147	pushl %esi # real mode pointer as second arg
1da177e4	148	call decompress_kernel
968de4f0 EB	149	addl $20, %esp
	150	popl %ecx
	151
	152	#if CONFIG_RELOCATABLE
	153	/* Find the address of the relocations.
	154	*/
	155	movl %ebp, %edi
	156	addl %ecx, %edi
	157
	158	/* Calculate the delta between where vmlinux was compiled to run
	159	* and where it was actually loaded.
	160	*/
	161	movl %ebp, %ebx
e69f202d VG	162	subl $LOAD_PHYSICAL_ADDR, %ebx
e69f202d VG	163	jz 2f /* Nothing to be done if loaded at compiled addr. */
1da177e4	164	/*
968de4f0	165	* Process relocations.
1da177e4	166	*/
968de4f0 EB	167
	168	1: subl $4, %edi
	169	movl 0(%edi), %ecx
	170	testl %ecx, %ecx
	171	jz 2f
	172	addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
	173	jmp 1b
	174	2:
	175	#endif
1da177e4 LT	176
1da177e4 LT	177	/*
968de4f0	178	* Jump to the decompressed kernel.
1da177e4	179	*/
1da177e4	180	xorl %ebx,%ebx
968de4f0 EB	181	jmp *%ebp
	182
	183	.bss
7c539764	184	/* Stack and heap for uncompression */
968de4f0	185	.balign 4
7c539764 AH	186	boot_heap:
	187	.fill BOOT_HEAP_SIZE, 1, 0
	188	boot_stack:
	189	.fill BOOT_STACK_SIZE, 1, 0
	190	boot_stack_end: