477 lines
9.9 KiB
ArmAsm
477 lines
9.9 KiB
ArmAsm
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/*
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* exec_kernel/user_space/head.S
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*
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* Copyright (C) 2000, 2002, 2003 Eric Biederman
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*
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* Parts of this code were take from the linux startup
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* code of linux-2.4.0-test9
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*
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* Other parts were taken from etherboot-5.0.5
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*/
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#define ASSEMBLY 1
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#define RELOC 0x10000
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#define PROT_CODE_SEG 0x10
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#define PROT_DATA_SEG 0x18
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#define REAL_CODE_SEG 0x08
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#define REAL_DATA_SEG 0x20
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.equ CR0_PE,1
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.text
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.code32
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#include "convert.h"
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.globl startup_32
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startup_32:
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cld
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cli
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# Save the arguments safely out of the way
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movl %eax, boot_type
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movl %ebx, boot_data
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cmp $0,%esp
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jz 1f
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movl 4(%esp), %eax
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movl %eax, boot_param
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1:
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movl stack_start, %esp
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# Clear eflags
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pushl $0
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popfl
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# Clear BSS
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xorl %eax,%eax
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movl $ _edata,%edi
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movl $ _end,%ecx
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subl %edi,%ecx
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cld
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rep
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stosb
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# Move the gdt where Linux will not smash it during decompression
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movl $gdt, %esi
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movl $GDTLOC, %edi
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movl $(gdt_end - gdt), %ecx
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rep movsb
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# Linux makes stupid assumptions about the segments
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# that are already setup, so setup a new gdt & ldt
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# and then reload the segment registers.
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lgdt gdt_48
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lidt idt_48
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# Load the data segment registers
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movl $ PROT_DATA_SEG, %eax
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movl %eax, %ds
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movl %eax, %es
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movl %eax, %fs
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movl %eax, %gs
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movl %eax, %ss
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pushl $image_params # image build time parameters as forth arg
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pushl boot_param # boot_param pointer as third arg
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pushl boot_data # boot data pointer as second arg
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pushl boot_type # boot data type as first argument
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call convert_params
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movl %eax, %esi # put the real mode pointer in a safe place
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addl $16, %esp # pop the arguments
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# Setup the registers before jumping to linux
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# clear eflags
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pushl $0
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popfl
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# Flag to indicate we are the bootstrap processor
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xorl %ebx, %ebx
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# Clear the unspecified registers for good measure
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xorl %eax, %eax
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xorl %ecx, %ecx
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xorl %edx, %edx
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xorl %edi, %edi
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xorl %esp, %esp
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xorl %ebp, %ebp
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# Jump to the linux kernel
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ljmp $ PROT_CODE_SEG , $ 0x100000
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/* Routines to query the BIOS... */
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/**************************************************************************
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E820_MEMSIZE - Get a listing of memory regions
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**************************************************************************/
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#define SMAP 0x534d4150
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.globl meme820
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meme820:
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pushl %ebp
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movl %esp, %ebp
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pushl %ebx
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pushl %esi
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pushl %edi
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movl 8(%ebp), %edi /* Address to return e820 structures at */
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subl $RELOC, %edi
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movl 12(%ebp), %esi /* Maximum number of e820 structurs to return */
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pushl %esi
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call _prot_to_real
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.code16
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xorl %ebx, %ebx
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jmpe820:
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movl $0xe820, %eax
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movl $SMAP, %edx
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movl $20, %ecx
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/* %di was setup earlier */
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int $0x15
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jc bail820
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cmpl $SMAP, %eax
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jne bail820
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good820:
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/* If this is useable memory, we save it by simply advancing %di by
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* sizeof(e820rec)
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*/
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decl %esi
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testl %esi,%esi
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jz bail820
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addw $20, %di
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again820:
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cmpl $0, %ebx /* check to see if %ebx is set to EOF */
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jne jmpe820
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bail820:
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data32 call _real_to_prot
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.code32
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popl %eax
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subl %esi, %eax /* Compute how many structure we read */
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/* Restore everything else */
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popl %edi
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popl %esi
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popl %ebx
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movl %ebp, %esp
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popl %ebp
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ret
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/**************************************************************************
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MEME801 - Determine size of extended memory
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**************************************************************************/
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.globl meme801
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meme801:
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pushl %ebx
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pushl %esi
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pushl %edi
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call _prot_to_real
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.code16
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stc # fix to work around buggy
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xorw %cx,%cx # BIOSes which dont clear/set
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xorw %dx,%dx # carry on pass/error of
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# e801h memory size call
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# or merely pass cx,dx though
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# without changing them.
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movw $0xe801,%ax
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int $0x15
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jc e801absent
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cmpw $0x0, %cx # Kludge to handle BIOSes
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jne e801usecxdx # which report their extended
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cmpw $0x0, %dx # memory in AX/BX rather than
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jne e801usecxdx # CX/DX. The spec I have read
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movw %ax, %cx # seems to indicate AX/BX
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movw %bx, %dx # are more reasonable anyway...
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e801usecxdx:
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andl $0xffff, %edx # clear sign extend
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shll $6, %edx # and go from 64k to 1k chunks
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movl %edx, %eax # store extended memory size
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andl $0xffff, %ecx # clear sign extend
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addl %ecx, %eax # and add lower memory into
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jmp e801out
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e801absent:
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xorl %eax,%eax
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e801out:
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data32 call _real_to_prot
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.code32
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/* Restore Everything */
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popl %edi
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popl %esi
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popl %ebx
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ret
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/**************************************************************************
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MEM88 - Determine size of extended memory
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**************************************************************************/
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.globl mem88
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mem88:
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pushl %ebx
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pushl %esi
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pushl %edi
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call _prot_to_real
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.code16
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movb $0x88, %ah
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int $0x15
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andl $0xffff, %eax
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data32 call _real_to_prot
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.code32
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/* Restore Everything */
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popl %edi
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popl %esi
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popl %ebx
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ret
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/**************************************************************************
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BASEMEMSIZE - Get size of the conventional (base) memory
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**************************************************************************/
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.globl basememsize
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basememsize:
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call _prot_to_real
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.code16
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int $0x12
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movw %ax,%cx
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DATA32 call _real_to_prot
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.code32
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movw %cx,%ax
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ret
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/**************************************************************************
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_REAL_TO_PROT - Go from REAL mode to Protected Mode
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**************************************************************************/
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.globl _real_to_prot
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_real_to_prot:
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.code16
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cli
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cs
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addr32 lgdt gdt_48 - RELOC
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movl %cr0,%eax
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orl $CR0_PE,%eax
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movl %eax,%cr0 /* turn on protected mode */
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/* flush prefetch queue, and reload %cs:%eip */
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data32 ljmp $PROT_CODE_SEG,$1f
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1:
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.code32
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/* reload other segment registers */
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movl $PROT_DATA_SEG,%eax
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movl %eax,%ds
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movl %eax,%es
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movl %eax,%ss
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addl $RELOC,%esp /* Fix up stack pointer */
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xorl %eax,%eax
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movl %eax,%fs
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movl %eax,%gs
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popl %eax /* Fix up return address */
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addl $RELOC,%eax
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pushl %eax
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/* switch to protected mode idt */
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cs
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lidt idt_48
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ret
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/**************************************************************************
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_PROT_TO_REAL - Go from Protected Mode to REAL Mode
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**************************************************************************/
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.globl _prot_to_real
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_prot_to_real:
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.code32
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popl %eax
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subl $RELOC,%eax /* Adjust return address */
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pushl %eax
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subl $RELOC,%esp /* Adjust stack pointer */
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ljmp $REAL_CODE_SEG,$1f- RELOC /* jump to a 16 bit segment */
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1:
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.code16
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/* clear the PE bit of CR0 */
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movl %cr0,%eax
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andl $0!CR0_PE,%eax
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movl %eax,%cr0
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/* make intersegment jmp to flush the processor pipeline
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* and reload %cs:%eip (to clear upper 16 bits of %eip).
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*/
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data32 ljmp $(RELOC)>>4,$2f- RELOC
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2:
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/* we are in real mode now
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* set up the real mode segment registers : %ds, $ss, %es
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*/
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movw %cs,%ax
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movw %ax,%ds
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movw %ax,%es
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movw %ax,%ss
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movw %ax,%fs
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movw %ax,%gs
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/* Switch to the real mode idt */
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cs
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addr32 lidt idt_real - RELOC
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sti
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data32 ret /* There is a 32 bit return address on the stack */
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.code32
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boot_type: .long 0
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boot_data: .long 0
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boot_param: .long 0
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idt_real:
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.word 0x400 # idt limit = 256
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.word 0, 0
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idt_48:
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.word 0 # idt limit = 0
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.word 0, 0 # idt base = 0L
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gdt_48:
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.word gdt_end - gdt - 1 # gdt limit=40,
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# (5 GDT entries)
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.long GDTLOC # gdt base
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# Descriptor tables
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# These need to be in a seperate section so I can be
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# certain later activities dont stomp them
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gdt:
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/* 0x00 */
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.word 0, 0, 0, 0 # dummy
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/* 0x08 */
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/* 16 bit real mode code segment */
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.word 0xffff,(RELOC&0xffff)
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.byte (RELOC>>16),0x9b,0x00,(RELOC>>24)
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/* 0x10 */
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.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
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.word 0 # base address = 0
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.word 0x9A00 # code read/exec
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.word 0x00CF # granularity = 4096, 386
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# (+5th nibble of limit)
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/* 0x18 */
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.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
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.word 0 # base address = 0
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.word 0x9200 # data read/write
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.word 0x00CF # granularity = 4096, 386
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# (+5th nibble of limit)
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/* 0x20 */
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/* 16 bit real mode data segment */
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.word 0xffff,(RELOC&0xffff)
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.byte (RELOC>>16),0x93,0x00,(RELOC>>24)
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/* For 2.5.x the kernel segments have moved */
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/* 0x28 dummy */
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.quad 0
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/* 0x30 dummy */
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.quad 0
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/* 0x38 dummy */
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.quad 0
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/* 0x40 dummy */
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.quad 0
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/* 0x48 dummy */
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.quad 0
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/* 0x50 dummy */
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.quad 0
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/* 0x58 dummy */
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.quad 0
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/* 0x60 */
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.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
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.word 0 # base address = 0
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.word 0x9A00 # code read/exec
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.word 0x00CF # granularity = 4096, 386
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# (+5th nibble of limit)
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/* 0x68 */
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.word 0xFFFF # 4Gb - (0x100000*0x1000 = 4Gb)
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.word 0 # base address = 0
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.word 0x9200 # data read/write
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||
|
|
.word 0x00CF # granularity = 4096, 386
|
||
|
|
# (+5th nibble of limit)
|
||
|
|
/*
|
||
|
|
* The layout of the per-CPU GDT under Linux:
|
||
|
|
*
|
||
|
|
* 0 - null
|
||
|
|
* 1 - reserved
|
||
|
|
* 2 - reserved
|
||
|
|
* 3 - reserved
|
||
|
|
*
|
||
|
|
* 4 - default user CS <==== new cacheline
|
||
|
|
* 5 - default user DS
|
||
|
|
*
|
||
|
|
* ------- start of TLS (Thread-Local Storage) segments:
|
||
|
|
*
|
||
|
|
* 6 - TLS segment #1 [ glibc's TLS segment ]
|
||
|
|
* 7 - TLS segment #2 [ Wine's %fs Win32 segment ]
|
||
|
|
* 8 - TLS segment #3
|
||
|
|
* 9 - reserved
|
||
|
|
* 10 - reserved
|
||
|
|
* 11 - reserved
|
||
|
|
*
|
||
|
|
* ------- start of kernel segments:
|
||
|
|
*
|
||
|
|
* 12 - kernel code segment <==== new cacheline
|
||
|
|
* 13 - kernel data segment
|
||
|
|
* 14 - TSS
|
||
|
|
* 15 - LDT
|
||
|
|
* 16 - PNPBIOS support (16->32 gate)
|
||
|
|
* 17 - PNPBIOS support
|
||
|
|
* 18 - PNPBIOS support
|
||
|
|
* 19 - PNPBIOS support
|
||
|
|
* 20 - PNPBIOS support
|
||
|
|
* 21 - APM BIOS support
|
||
|
|
* 22 - APM BIOS support
|
||
|
|
* 23 - APM BIOS support
|
||
|
|
*/
|
||
|
|
gdt_end:
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
.section ".trailer", "a"
|
||
|
|
/* Constants set at build time, these are at the very end of my image */
|
||
|
|
.balign 16
|
||
|
|
.global image_params
|
||
|
|
image_params:
|
||
|
|
|
||
|
|
convert_magic:
|
||
|
|
.long CONVERT_MAGIC
|
||
|
|
gdt_size:
|
||
|
|
.long gdt_end - gdt
|
||
|
|
bss_size:
|
||
|
|
.long bss_size
|
||
|
|
ramdisk_flags:
|
||
|
|
.word 0
|
||
|
|
root_dev:
|
||
|
|
.word DEFAULT_ROOT_DEV
|
||
|
|
entry:
|
||
|
|
.long 0
|
||
|
|
initrd_start:
|
||
|
|
.long 0
|
||
|
|
initrd_size:
|
||
|
|
.long 0
|
||
|
|
cmdline:
|
||
|
|
.asciz "BOOT_IMAGE=head.S console=ttyS0 ip=dhcp root=/dev/nfs"
|
||
|
|
.org cmdline + CMDLINE_MAX, 0
|
||
|
|
cmdline_end:
|