86 строки
2.4 KiB
ArmAsm
86 строки
2.4 KiB
ArmAsm
/*
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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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* In fact we don't actually need a stack so we don't
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* set one up.
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*
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* We jump into the boot/compressed/head.S code. So you'd
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* better be running a compressed kernel image or you
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* won't get very far.
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*
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* On entry to trampoline_data, 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, data addresses need to be absolute
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* (no relocation) and are taken with regard to r_base.
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*
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* If you work on this file, check the object module with
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* objdump --reloc to make sure there are no relocation
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* entries except for:
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*
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* TYPE VALUE
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* R_386_32 startup_32_smp
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* R_386_32 boot_gdt
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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.h>
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.data
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/* We can free up trampoline after bootup if cpu hotplug is not supported. */
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#ifndef CONFIG_HOTPLUG_CPU
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.section ".init.data","aw",@progbits
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#endif
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.code16
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ENTRY(trampoline_data)
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r_base = .
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wbinvd # Needed for NUMA-Q should be harmless for others
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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 $0xA5A5A5A5, trampoline_data - r_base
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# write marker for master knows we're running
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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 boot_idt_descr - r_base # load idt with 0, 0
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lgdtl boot_gdt_descr - r_base # load gdt with whatever is appropriate
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xor %ax, %ax
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inc %ax # protected mode (PE) bit
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lmsw %ax # into protected mode
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# flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S
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ljmpl $__BOOT_CS, $(startup_32_smp-__PAGE_OFFSET)
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# These need to be in the same 64K segment as the above;
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# hence we don't use the boot_gdt_descr defined in head.S
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boot_gdt_descr:
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.word __BOOT_DS + 7 # gdt limit
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.long boot_gdt - __PAGE_OFFSET # gdt base
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boot_idt_descr:
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.word 0 # idt limit = 0
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.long 0 # idt base = 0L
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.globl trampoline_end
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trampoline_end:
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