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// Rom layout and bios assembler to C interface.
//
// Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
// Copyright (C) 2002 MandrakeSoft S.A.
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
/****************************************************************
* Include of 16bit C code
****************************************************************/
.code16gcc
.include "out/ccode.16.s"
#include "config.h" // CONFIG_*
#include "ioport.h" // PORT_A20
#include "bregs.h" // CR0_*
#include "cmos.h" // CMOS_RESET_CODE
#include "../out/asm-offsets.h" // BREGS_*
#include "entryfuncs.S" // ENTRY_*
/****************************************************************
* Call trampolines
****************************************************************/
// Place CPU into 32bit mode from 16bit mode.
// Clobbers: flags, segment registers, cr0, idt/gdt
DECLFUNC transition32
transition32:
pushl %eax
// Disable irqs (and clear direction flag)
cli
cld
// Disable nmi
movl $CMOS_RESET_CODE|NMI_DISABLE_BIT, %eax
outb %al, $PORT_CMOS_INDEX
inb $PORT_CMOS_DATA, %al
// enable a20
inb $PORT_A20, %al
orb $A20_ENABLE_BIT, %al
outb %al, $PORT_A20
// Set segment descriptors
lidtw %cs:pmode_IDT_info
lgdtw %cs:rombios32_gdt_48
// Enable protected mode
movl %cr0, %eax
orl $CR0_PE, %eax
movl %eax, %cr0
// start 32bit protected mode code
ljmpl $SEG32_MODE32_CS, $(BUILD_BIOS_ADDR + 1f)
.code32
1:
// init data segments
movl $SEG32_MODE32_DS, %eax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw %ax, %fs
movw %ax, %gs
popl %eax
retl
// Call a 16bit function from 32bit mode.
// %eax = address of struct bregs
// Clobbers: %e[bcd]x, %e[ds]i, flags, segment registers, idt/gdt
DECLFUNC __call16_from32
.global __call16big_from32
__call16_from32:
pushl %eax
// restore data segment limits to 0xffff
movl $SEG32_MODE16_DS, %eax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw %ax, %fs
movw %ax, %gs
#if CONFIG_DISABLE_A20
// disable a20
inb $PORT_A20, %al
andb $~A20_ENABLE_BIT, %al
outb %al, $PORT_A20
#endif
// Jump to 16bit mode
ljmpw $SEG32_MODE16_CS, $1f
__call16big_from32:
pushl %eax
movl $SEG32_MODE16BIG_DS, %eax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw %ax, %fs
movw %ax, %gs
ljmpl $SEG32_MODE16BIG_CS, $(BUILD_BIOS_ADDR + 1f)
.code16gcc
1:
// Disable protected mode
movl %cr0, %eax
andl $~CR0_PE, %eax
movl %eax, %cr0
// far jump to flush CPU queue after transition to real mode
ljmpw $SEG_BIOS, $2f
2:
// restore IDT to normal real-mode defaults
lidtw %cs:rmode_IDT_info
// Clear segment registers
xorw %ax, %ax
movw %ax, %fs
movw %ax, %gs
movw %ax, %es
movw %ax, %ds
movw %ax, %ss // Assume stack is in segment 0
popl %eax
// Make call.
calll __call16
// Return via transition32
jmp transition32
// Call a 16bit function from 16bit mode with a specified cpu register state
// %eax = address of struct bregs
// Clobbers: %e[bcd]x, %e[ds]i, flags
DECLFUNC __call16
__call16:
// Save %eax, %ebp
pushl %ebp
pushl %eax
// Setup for iretw call
pushw %cs
pushw $1f // return point
pushw BREGS_flags(%eax) // flags
pushl BREGS_ip(%eax) // CS:IP
// Load calling registers.
movl BREGS_edi(%eax), %edi
movl BREGS_esi(%eax), %esi
movl BREGS_ebx(%eax), %ebx
movl BREGS_edx(%eax), %edx
movl BREGS_ecx(%eax), %ecx
movw BREGS_es(%eax), %es
movw BREGS_ds(%eax), %ds
movl %ss:BREGS_eax(%eax), %eax
// Invoke call
iretw // XXX - just do a lcalll
1:
// Store flags, eax, ecx
pushfw
pushl %eax
movl 0x06(%esp), %eax
movl %ecx, %ss:BREGS_ecx(%eax)
movw %ds, %ss:BREGS_ds(%eax)
movw %ss, %cx
movw %cx, %ds // Restore %ds == %ss
popl %ecx
movl %ecx, BREGS_eax(%eax)
popw %cx
movw %cx, BREGS_flags(%eax)
// Store remaining registers
movw %es, BREGS_es(%eax)
movl %edi, BREGS_edi(%eax)
movl %esi, BREGS_esi(%eax)
movl %ebx, BREGS_ebx(%eax)
movl %edx, BREGS_edx(%eax)
// Remove %eax, restore %ebp
popl %eax
popl %ebp
retl
// IRQ trampolines
.macro IRQ_TRAMPOLINE num
DECLFUNC irq_trampoline_0x\num
irq_trampoline_0x\num :
int $0x\num
lretw
.endm
IRQ_TRAMPOLINE 10
IRQ_TRAMPOLINE 13
IRQ_TRAMPOLINE 15
IRQ_TRAMPOLINE 16
IRQ_TRAMPOLINE 18
IRQ_TRAMPOLINE 19
/****************************************************************
* POST entry point
****************************************************************/
DECLFUNC entry_post
entry_post:
// Enable cache
movl %cr0, %eax
andl $~(CR0_CD|CR0_NW), %eax
movl %eax, %cr0
// Disable interrupts
cli
cld
// Check for restart indicator.
movl $CMOS_RESET_CODE|NMI_DISABLE_BIT, %eax
outb %al, $PORT_CMOS_INDEX
inb $PORT_CMOS_DATA, %al
cmpb $0x0, %al
jnz 1f
// Normal entry point
ENTRY_INTO32 _code32__start
// Entry point when a post call looks like a resume.
1:
// Save old shutdown status.
movl %eax, %ebx
// Clear shutdown status register.
movl $CMOS_RESET_CODE|NMI_DISABLE_BIT, %eax
outb %al, $PORT_CMOS_INDEX
xorl %eax, %eax
outb %al, $PORT_CMOS_DATA
// Use a stack in EBDA
movw $SEG_BDA, %ax
movw %ax, %ds
movw BDA_ebda_seg, %ax
// XXX - should verify ebda_seg looks sane.
movw %ax, %ds
movw %ax, %ss
movl $EBDA_OFFSET_TOP_STACK, %esp
// Call handler.
movl %ebx, %eax
jmp handle_resume
/****************************************************************
* Misc. entry points.
****************************************************************/
// PnP entry points
DECLFUNC entry_pnp_real
.global entry_pnp_prot
entry_pnp_prot:
pushl %esp
jmp 1f
entry_pnp_real:
pushl %esp // Backup %esp, then clear high bits
movzwl %sp, %esp
1:
pushfl // Save registers clobbered by C code
pushl %eax
pushl %ecx
pushl %edx
pushw %es
pushw %ds
movw %ss, %cx // Move %ss to %ds
movw %cx, %ds
lea 28(%esp), %eax // %eax points to start of u16 args
calll handle_pnp
movw %ax, 12(%esp) // Modify %eax to return %ax
popw %ds
popw %es
popl %edx
popl %ecx
popl %eax
popfl
popl %esp
lretw
// APM entry points
DECLFUNC apm16protected_entry
apm16protected_entry:
pushfw // save flags
pushl %eax // dummy
ENTRY_ARG handle_1553
addw $4, %sp // pop dummy
popfw // restore flags
lretw
.code32
DECLFUNC apm32protected_entry
apm32protected_entry:
pushfw
pushw %cs // Setup for long jump to 16bit mode
pushw $1f
addw $8, 2(%esp)
ljmpw *(%esp)
.code16gcc
1:
ENTRY_ARG_ESP handle_1553
movw $2f,(%esp) // Setup for long jump back to 32bit mode
subw $8, 2(%esp)
ljmpw *(%esp)
.code32
2:
addl $4, %esp // pop call address
popfw
lretl
// 32bit elf entry point
DECLFUNC post32
post32:
cli
cld
lidtl (BUILD_BIOS_ADDR + pmode_IDT_info)
lgdtl (BUILD_BIOS_ADDR + rombios32_gdt_48)
movl $SEG32_MODE32_DS, %eax
movw %ax, %ds
movw %ax, %es
movw %ax, %fs
movw %ax, %gs
movw %ax, %ss
movl $BUILD_STACK_ADDR, %esp
ljmpl $SEG32_MODE32_CS, $_code32__start
.code16gcc
/****************************************************************
* Interrupt entry points
****************************************************************/
// Define an entry point for an interrupt (no args passed).
.macro IRQ_ENTRY num
.global entry_\num
entry_\num :
pushl $ handle_\num
jmp irqentry
.endm
// Define an entry point for an interrupt (can read/modify args).
.macro IRQ_ENTRY_ARG num
.global entry_\num
entry_\num :
pushl $ handle_\num
jmp irqentryarg
.endm
// Macros that put each handler into its own section
.macro DECL_IRQ_ENTRY num
DECLFUNC entry_\num
IRQ_ENTRY \num
.endm
.macro DECL_IRQ_ENTRY_ARG num
DECLFUNC entry_\num
IRQ_ENTRY_ARG \num
.endm
// Main entry point for interrupts without args
DECLFUNC irqentry
irqentry:
ENTRY_ST
iretw
// Main entry point for interrupts with args
DECLFUNC irqentry
irqentryarg:
ENTRY_ARG_ST
iretw
DECL_IRQ_ENTRY_ARG 13
DECL_IRQ_ENTRY 76
DECL_IRQ_ENTRY 70
DECL_IRQ_ENTRY 74
DECL_IRQ_ENTRY 75
DECL_IRQ_ENTRY hwpic1
DECL_IRQ_ENTRY hwpic2
// int 18/19 are special - they reset stack and call into 32bit mode.
DECLFUNC entry_19
entry_19:
ENTRY_INTO32 _code32_handle_19
DECLFUNC entry_18
entry_18:
ENTRY_INTO32 _code32_handle_18
/****************************************************************
* Fixed position entry points
****************************************************************/
// Specify a location in the fixed part of bios area.
.macro ORG addr
.section .fixedaddr.\addr
.endm
ORG 0xe05b
entry_post_official:
jmp entry_post
ORG 0xe2c3
IRQ_ENTRY 02
ORG 0xe3fe
.global entry_13_official
entry_13_official:
jmp entry_13
// 0xe401 - OldFDPT in disk.c
ORG 0xe6f2
.global entry_19_official
entry_19_official:
jmp entry_19
// 0xe6f5 - BIOS_CONFIG_TABLE in misc.c
// 0xe729 - BaudTable in serial.c
ORG 0xe739
IRQ_ENTRY_ARG 14
ORG 0xe82e
IRQ_ENTRY_ARG 16
ORG 0xe987
IRQ_ENTRY 09
ORG 0xec59
IRQ_ENTRY_ARG 40
ORG 0xef57
IRQ_ENTRY 0e
// 0xefc7 - diskette_param_table in floppy.c
ORG 0xefd2
IRQ_ENTRY_ARG 17
ORG 0xf045
entry_10_0x0f:
// XXX - INT 10 Functions 0-Fh Entry Point
iretw
ORG 0xf065
IRQ_ENTRY_ARG 10
// 0xf0a4 - VideoParams in misc.c
ORG 0xf841
IRQ_ENTRY_ARG 12
ORG 0xf84d
IRQ_ENTRY_ARG 11
ORG 0xf859
IRQ_ENTRY_ARG 15
// 0xfa6e - vgafont8 in font.c
ORG 0xfe6e
IRQ_ENTRY_ARG 1a
ORG 0xfea5
IRQ_ENTRY 08
// 0xfef3 - InitVectors in misc.c
// 0xff00 - BiosCopyright in misc.c
ORG 0xff53
.global entry_iret_official
entry_iret_official:
iretw
ORG 0xff54
IRQ_ENTRY_ARG 05
ORG 0xfff0 // Power-up Entry Point
.global reset_vector
reset_vector:
ljmpw $SEG_BIOS, $entry_post_official
// 0xfff5 - BiosDate in misc.c
// 0xfffe - BiosModelId in misc.c
// 0xffff - BiosChecksum in misc.c
.end