| /* |
| * |
| * 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_data, the processor is in real mode |
| * with 16-bit addressing and 16-bit data. CS has some value |
| * and IP is zero. Thus, data addresses need to be absolute |
| * (no relocation) and are taken with regard to r_base. |
| * |
| * If you work on this file, check the object module with |
| * objdump --reloc to make sure there are no relocation |
| * entries except for: |
| * |
| * TYPE VALUE |
| * R_386_32 startup_32_smp |
| * R_386_32 boot_gdt |
| */ |
| |
| #include <linux/linkage.h> |
| #include <asm/segment.h> |
| #include <asm/page.h> |
| |
| /* We can free up trampoline after bootup if cpu hotplug is not supported. */ |
| #ifndef CONFIG_HOTPLUG_CPU |
| .section ".init.data","aw",@progbits |
| #else |
| .section .rodata,"a",@progbits |
| #endif |
| |
| .code16 |
| |
| ENTRY(trampoline_data) |
| r_base = . |
| wbinvd # Needed for NUMA-Q should be harmless for others |
| mov %cs, %ax # Code and data in the same place |
| mov %ax, %ds |
| |
| cli # We should be safe anyway |
| |
| movl $0xA5A5A5A5, trampoline_data - r_base |
| # 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 boot_idt_descr - r_base # load idt with 0, 0 |
| lgdtl boot_gdt_descr - r_base # load gdt with whatever is appropriate |
| |
| xor %ax, %ax |
| inc %ax # protected mode (PE) bit |
| lmsw %ax # into protected mode |
| # flush prefetch and jump to startup_32_smp in arch/i386/kernel/head.S |
| ljmpl $__BOOT_CS, $(startup_32_smp-__PAGE_OFFSET) |
| |
| # These need to be in the same 64K segment as the above; |
| # hence we don't use the boot_gdt_descr defined in head.S |
| boot_gdt_descr: |
| .word __BOOT_DS + 7 # gdt limit |
| .long boot_gdt - __PAGE_OFFSET # gdt base |
| |
| boot_idt_descr: |
| .word 0 # idt limit = 0 |
| .long 0 # idt base = 0L |
| |
| .globl trampoline_end |
| trampoline_end: |
