/* SPDX-License-Identifier: GPL-2.0 */
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/*
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*
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* Trampoline.S Derived from Setup.S by Linus Torvalds
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*
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* 4 Jan 1997 Michael Chastain: changed to gnu as.
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*
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* This is only used for booting secondary CPUs in SMP machine
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*
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* Entry: CS:IP point to the start of our code, we are
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* in real mode with no stack, but the rest of the
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* trampoline page to make our stack and everything else
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* is a mystery.
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*
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* We jump into arch/x86/kernel/head_32.S.
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*
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* On entry to trampoline_start, the processor is in real mode
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* with 16-bit addressing and 16-bit data. CS has some value
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* and IP is zero. Thus, we load CS to the physical segment
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* of the real mode code before doing anything further.
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*/
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#include <linux/linkage.h>
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#include <asm/segment.h>
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#include <asm/page_types.h>
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#include "realmode.h"
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.text
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.code16
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.balign PAGE_SIZE
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SYM_CODE_START(trampoline_start)
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wbinvd # Needed for NUMA-Q should be harmless for others
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LJMPW_RM(1f)
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1:
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mov %cs, %ax # Code and data in the same place
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mov %ax, %ds
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cli # We should be safe anyway
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movl tr_start, %eax # where we need to go
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/*
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* GDT tables in non default location kernel can be beyond 16MB and
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* lgdt will not be able to load the address as in real mode default
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* operand size is 16bit. Use lgdtl instead to force operand size
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* to 32 bit.
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*/
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lidtl tr_idt # load idt with 0, 0
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lgdtl tr_gdt # load gdt with whatever is appropriate
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movw $1, %dx # protected mode (PE) bit
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lmsw %dx # into protected mode
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ljmpl $__BOOT_CS, $pa_startup_32
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SYM_CODE_END(trampoline_start)
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.section ".text32","ax"
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.code32
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SYM_CODE_START(startup_32) # note: also used from wakeup_asm.S
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jmp *%eax
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SYM_CODE_END(startup_32)
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.bss
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.balign 8
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SYM_DATA_START(trampoline_header)
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SYM_DATA_LOCAL(tr_start, .space 4)
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SYM_DATA_LOCAL(tr_gdt_pad, .space 2)
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SYM_DATA_LOCAL(tr_gdt, .space 6)
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SYM_DATA_END(trampoline_header)
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#include "trampoline_common.S"
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