192 lines
4.1 KiB
ArmAsm
192 lines
4.1 KiB
ArmAsm
/*
|
|
* 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_types.h>
|
|
#include <asm/boot.h>
|
|
#include <asm/asm-offsets.h>
|
|
|
|
.section ".text.head","ax",@progbits
|
|
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 (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
|
|
ENDPROC(startup_32)
|
|
|
|
.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
|
|
# push arguments for decompress_kernel:
|
|
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
|
|
pushl %esi # real mode pointer
|
|
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:
|