You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
182 lines
3.8 KiB
182 lines
3.8 KiB
/*
|
|
* 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/init.h>
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
#include <asm/page_types.h>
|
|
#include <asm/boot.h>
|
|
#include <asm/asm-offsets.h>
|
|
|
|
__HEAD
|
|
ENTRY(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 (BP_scratch+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
|
|
movl BP_kernel_alignment(%esi), %eax
|
|
decl %eax
|
|
addl %eax, %ebx
|
|
notl %eax
|
|
andl %eax, %ebx
|
|
#else
|
|
movl $LOAD_PHYSICAL_ADDR, %ebx
|
|
#endif
|
|
|
|
/* Target address to relocate to for decompression */
|
|
addl $z_extract_offset, %ebx
|
|
|
|
/* Set up the stack */
|
|
leal boot_stack_end(%ebx), %esp
|
|
|
|
/* Zero EFLAGS */
|
|
pushl $0
|
|
popfl
|
|
|
|
/*
|
|
* Copy the compressed kernel to the end of our buffer
|
|
* where decompression in place becomes safe.
|
|
*/
|
|
pushl %esi
|
|
leal (_bss-4)(%ebp), %esi
|
|
leal (_bss-4)(%ebx), %edi
|
|
movl $(_bss - startup_32), %ecx
|
|
shrl $2, %ecx
|
|
std
|
|
rep movsl
|
|
cld
|
|
popl %esi
|
|
|
|
/*
|
|
* Jump to the relocated address.
|
|
*/
|
|
leal relocated(%ebx), %eax
|
|
jmp *%eax
|
|
ENDPROC(startup_32)
|
|
|
|
.text
|
|
relocated:
|
|
|
|
/*
|
|
* Clear BSS (stack is currently empty)
|
|
*/
|
|
xorl %eax, %eax
|
|
leal _bss(%ebx), %edi
|
|
leal _ebss(%ebx), %ecx
|
|
subl %edi, %ecx
|
|
shrl $2, %ecx
|
|
rep stosl
|
|
|
|
/*
|
|
* Do the decompression, and jump to the new kernel..
|
|
*/
|
|
leal z_extract_offset_negative(%ebx), %ebp
|
|
/* push arguments for decompress_kernel: */
|
|
pushl %ebp /* output address */
|
|
pushl $z_input_len /* input_len */
|
|
leal input_data(%ebx), %eax
|
|
pushl %eax /* input_data */
|
|
leal boot_heap(%ebx), %eax
|
|
pushl %eax /* heap area */
|
|
pushl %esi /* real mode pointer */
|
|
call decompress_kernel
|
|
addl $20, %esp
|
|
|
|
#if CONFIG_RELOCATABLE
|
|
/*
|
|
* Find the address of the relocations.
|
|
*/
|
|
leal z_output_len(%ebp), %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 (%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
|
|
|
|
/*
|
|
* Stack and heap for uncompression
|
|
*/
|
|
.bss
|
|
.balign 4
|
|
boot_heap:
|
|
.fill BOOT_HEAP_SIZE, 1, 0
|
|
boot_stack:
|
|
.fill BOOT_STACK_SIZE, 1, 0
|
|
boot_stack_end:
|
|
|