/* * * 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"