83d290c56f
When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com>
304 lines
6.5 KiB
ArmAsm
304 lines
6.5 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* From coreboot x86_asm.S, cleaned up substantially
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*
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* Copyright (C) 2009-2010 coresystems GmbH
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*/
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#include <asm/processor.h>
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#include <asm/processor-flags.h>
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#include "bios.h"
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#define SEG(segment) $segment * X86_GDT_ENTRY_SIZE
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/*
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* This is the interrupt handler stub code. It gets copied to the IDT and
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* to some fixed addresses in the F segment. Before the code can used,
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* it gets patched up by the C function copying it: byte 3 (the $0 in
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* movb $0, %al) is overwritten with the interrupt numbers.
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*/
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.code16
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.globl __idt_handler
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__idt_handler:
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pushal
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movb $0, %al /* This instruction gets modified */
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ljmp $0, $__interrupt_handler_16bit
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.globl __idt_handler_size
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__idt_handler_size:
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.long . - __idt_handler
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.macro setup_registers
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/* initial register values */
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movl 44(%ebp), %eax
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movl %eax, __registers + 0 /* eax */
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movl 48(%ebp), %eax
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movl %eax, __registers + 4 /* ebx */
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movl 52(%ebp), %eax
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movl %eax, __registers + 8 /* ecx */
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movl 56(%ebp), %eax
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movl %eax, __registers + 12 /* edx */
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movl 60(%ebp), %eax
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movl %eax, __registers + 16 /* esi */
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movl 64(%ebp), %eax
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movl %eax, __registers + 20 /* edi */
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.endm
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.macro enter_real_mode
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/* Activate the right segment descriptor real mode. */
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ljmp SEG(X86_GDT_ENTRY_16BIT_CS), $PTR_TO_REAL_MODE(1f)
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1:
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.code16
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/*
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* Load the segment registers with properly configured segment
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* descriptors. They will retain these configurations (limits,
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* writability, etc.) once protected mode is turned off.
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*/
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mov SEG(X86_GDT_ENTRY_16BIT_DS), %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov %ax, %ss
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/* Turn off protection */
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movl %cr0, %eax
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andl $~X86_CR0_PE, %eax
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movl %eax, %cr0
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/* Now really going into real mode */
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ljmp $0, $PTR_TO_REAL_MODE(1f)
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1:
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/*
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* Set up a stack: Put the stack at the end of page zero. That way
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* we can easily share it between real and protected, since the
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* 16-bit ESP at segment 0 will work for any case.
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*/
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mov $0x0, %ax
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mov %ax, %ss
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/* Load 16 bit IDT */
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xor %ax, %ax
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mov %ax, %ds
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lidt __realmode_idt
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.endm
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.macro prepare_for_irom
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movl $0x1000, %eax
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movl %eax, %esp
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/* Initialise registers for option rom lcall */
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movl __registers + 0, %eax
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movl __registers + 4, %ebx
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movl __registers + 8, %ecx
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movl __registers + 12, %edx
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movl __registers + 16, %esi
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movl __registers + 20, %edi
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/* Set all segments to 0x0000, ds to 0x0040 */
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push %ax
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xor %ax, %ax
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mov %ax, %es
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mov %ax, %fs
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mov %ax, %gs
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mov SEG(X86_GDT_ENTRY_16BIT_FLAT_DS), %ax
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mov %ax, %ds
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pop %ax
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.endm
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.macro enter_protected_mode
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/* Go back to protected mode */
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movl %cr0, %eax
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orl $X86_CR0_PE, %eax
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movl %eax, %cr0
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/* Now that we are in protected mode jump to a 32 bit code segment */
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data32 ljmp SEG(X86_GDT_ENTRY_32BIT_CS), $PTR_TO_REAL_MODE(1f)
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1:
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.code32
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mov SEG(X86_GDT_ENTRY_32BIT_DS), %ax
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mov %ax, %ds
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mov %ax, %es
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mov %ax, %gs
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mov %ax, %ss
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mov SEG(X86_GDT_ENTRY_32BIT_FS), %ax
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mov %ax, %fs
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/* restore proper idt */
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lidt idt_ptr
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.endm
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/*
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* In order to be independent of U-Boot's position in RAM we relocate a part
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* of the code to the first megabyte of RAM, so the CPU can use it in
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* real-mode. This code lives at asm_realmode_code.
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*/
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.globl asm_realmode_code
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asm_realmode_code:
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/* Realmode IDT pointer structure. */
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__realmode_idt = PTR_TO_REAL_MODE(.)
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.word 1023 /* 16 bit limit */
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.long 0 /* 24 bit base */
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.word 0
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/* Preserve old stack */
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__stack = PTR_TO_REAL_MODE(.)
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.long 0
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/* Register store for realmode_call and realmode_interrupt */
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__registers = PTR_TO_REAL_MODE(.)
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.long 0 /* 0 - EAX */
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.long 0 /* 4 - EBX */
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.long 0 /* 8 - ECX */
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.long 0 /* 12 - EDX */
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.long 0 /* 16 - ESI */
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.long 0 /* 20 - EDI */
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/* 256 byte buffer, used by int10 */
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.globl asm_realmode_buffer
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asm_realmode_buffer:
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.skip 256
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.code32
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.globl asm_realmode_call
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asm_realmode_call:
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/* save all registers to the stack */
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pusha
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pushf
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movl %esp, __stack
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movl %esp, %ebp
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/*
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* This function is called with regparm=0 and we have to skip the
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* 36 bytes from pushf+pusha. Hence start at 40.
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* Set up our call instruction.
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*/
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movl 40(%ebp), %eax
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mov %ax, __lcall_instr + 1
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andl $0xffff0000, %eax
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shrl $4, %eax
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mov %ax, __lcall_instr + 3
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wbinvd
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setup_registers
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enter_real_mode
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prepare_for_irom
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__lcall_instr = PTR_TO_REAL_MODE(.)
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.byte 0x9a
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.word 0x0000, 0x0000
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enter_protected_mode
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/* restore stack pointer, eflags and register values and exit */
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movl __stack, %esp
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popf
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popa
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ret
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.globl __realmode_interrupt
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__realmode_interrupt:
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/* save all registers to the stack and store the stack pointer */
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pusha
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pushf
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movl %esp, __stack
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movl %esp, %ebp
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/*
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* This function is called with regparm=0 and we have to skip the
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* 36 bytes from pushf+pusha. Hence start at 40.
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* Prepare interrupt calling code.
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*/
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movl 40(%ebp), %eax
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movb %al, __intXX_instr + 1 /* intno */
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setup_registers
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enter_real_mode
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prepare_for_irom
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__intXX_instr = PTR_TO_REAL_MODE(.)
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.byte 0xcd, 0x00 /* This becomes intXX */
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enter_protected_mode
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/* restore stack pointer, eflags and register values and exit */
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movl __stack, %esp
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popf
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popa
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ret
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/*
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* This is the 16-bit interrupt entry point called by the IDT stub code.
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*
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* Before this code code is called, %eax is pushed to the stack, and the
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* interrupt number is loaded into %al. On return this function cleans up
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* for its caller.
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*/
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.code16
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__interrupt_handler_16bit = PTR_TO_REAL_MODE(.)
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push %ds
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push %es
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push %fs
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push %gs
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/* Save real mode SS */
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movw %ss, %cs:__realmode_ss
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/* Clear DF to not break ABI assumptions */
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cld
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/*
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* Clean up the interrupt number. We could do this in the stub, but
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* it would cost two more bytes per stub entry.
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*/
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andl $0xff, %eax
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pushl %eax /* ... and make it the first parameter */
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enter_protected_mode
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/*
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* Now we are in protected mode. We need compute the right ESP based
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* on saved real mode SS otherwise interrupt_handler() won't get
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* correct parameters from the stack.
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*/
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movzwl %cs:__realmode_ss, %ecx
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shll $4, %ecx
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addl %ecx, %esp
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/* Call the C interrupt handler */
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movl $interrupt_handler, %eax
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call *%eax
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/* Restore real mode ESP based on saved SS */
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movzwl %cs:__realmode_ss, %ecx
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shll $4, %ecx
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subl %ecx, %esp
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enter_real_mode
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/* Restore real mode SS */
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movw %cs:__realmode_ss, %ss
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/*
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* Restore all registers, including those manipulated by the C
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* handler
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*/
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popl %eax
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pop %gs
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pop %fs
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pop %es
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pop %ds
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popal
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iret
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__realmode_ss = PTR_TO_REAL_MODE(.)
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.word 0
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.globl asm_realmode_code_size
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asm_realmode_code_size:
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.long . - asm_realmode_code
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