72 lines
1.9 KiB
ArmAsm
72 lines
1.9 KiB
ArmAsm
/*
|
|
*
|
|
* Trampoline.S Derived from Setup.S by Linus Torvalds
|
|
*
|
|
* 4 Jan 1997 Michael Chastain: changed to gnu as.
|
|
*
|
|
* 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.
|
|
*
|
|
* In fact we don't actually need a stack so we don't
|
|
* set one up.
|
|
*
|
|
* 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
|
|
* --full-contents --reloc to make sure there are no relocation
|
|
* entries. For the GDT entry we do hand relocation in smpboot.c
|
|
* because of 64bit linker limitations.
|
|
*/
|
|
|
|
#include <linux/linkage.h>
|
|
#include <asm/segment.h>
|
|
#include <asm/page.h>
|
|
|
|
.data
|
|
|
|
.code16
|
|
|
|
ENTRY(trampoline_data)
|
|
r_base = .
|
|
wbinvd
|
|
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 idt_48 - r_base # load idt with 0, 0
|
|
lgdtl gdt_48 - r_base # load gdt with whatever is appropriate
|
|
|
|
xor %ax, %ax
|
|
inc %ax # protected mode (PE) bit
|
|
lmsw %ax # into protected mode
|
|
# flaush prefetch and jump to startup_32 in arch/x86_64/kernel/head.S
|
|
ljmpl $__KERNEL32_CS, $(startup_32-__START_KERNEL_map)
|
|
|
|
# Careful these need to be in the same 64K segment as the above;
|
|
idt_48:
|
|
.word 0 # idt limit = 0
|
|
.word 0, 0 # idt base = 0L
|
|
|
|
gdt_48:
|
|
.short __KERNEL32_CS + 7 # gdt limit
|
|
.long cpu_gdt_table-__START_KERNEL_map
|
|
|
|
.globl trampoline_end
|
|
trampoline_end:
|