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kernel/linux-rt-4.4.41/arch/x86/realmode/rm/trampoline_32.S 1.79 KB
5113f6f70   김현기   kernel add
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  /*
   *
   *	Trampoline.S	Derived from Setup.S by Linus Torvalds
   *
   *	4 Jan 1997 Michael Chastain: changed to gnu as.
   *
   *	This is only used for booting secondary CPUs in SMP machine
   *
   *	Entry: CS:IP point to the start of our code, we are
   *	in real mode with no stack, but the rest of the
   *	trampoline page to make our stack and everything else
   *	is a mystery.
   *
   *	We jump into arch/x86/kernel/head_32.S.
   *
   *	On entry to trampoline_start, the processor is in real mode
   *	with 16-bit addressing and 16-bit data.  CS has some value
   *	and IP is zero.  Thus, we load CS to the physical segment
   *	of the real mode code before doing anything further.
   */
  
  #include <linux/linkage.h>
  #include <asm/segment.h>
  #include <asm/page_types.h>
  #include "realmode.h"
  
  	.text
  	.code16
  
  	.balign	PAGE_SIZE
  ENTRY(trampoline_start)
  	wbinvd			# Needed for NUMA-Q should be harmless for others
  
  	LJMPW_RM(1f)
  1:
  	mov	%cs, %ax	# Code and data in the same place
  	mov	%ax, %ds
  
  	cli			# We should be safe anyway
  
  	movl	tr_start, %eax	# where we need to go
  
  	movl	$0xA5A5A5A5, trampoline_status
  				# write marker for master knows we're running
  
  	/*
  	 * GDT tables in non default location kernel can be beyond 16MB and
  	 * lgdt will not be able to load the address as in real mode default
  	 * operand size is 16bit. Use lgdtl instead to force operand size
  	 * to 32 bit.
  	 */
  	lidtl	tr_idt			# load idt with 0, 0
  	lgdtl	tr_gdt			# load gdt with whatever is appropriate
  
  	movw	$1, %dx			# protected mode (PE) bit
  	lmsw	%dx			# into protected mode
  
  	ljmpl	$__BOOT_CS, $pa_startup_32
  
  	.section ".text32","ax"
  	.code32
  ENTRY(startup_32)			# note: also used from wakeup_asm.S
  	jmp	*%eax
  
  	.bss
  	.balign 8
  GLOBAL(trampoline_header)
  	tr_start:		.space	4
  	tr_gdt_pad:		.space	2
  	tr_gdt:			.space	6
  END(trampoline_header)
  	
  #include "trampoline_common.S"