xv6-65oo2/entryother.S

94 lines
2.7 KiB
ArmAsm
Raw Normal View History

#include "asm.h"
#include "memlayout.h"
#include "mmu.h"
# Each non-boot CPU ("AP") is started up in response to a STARTUP
# IPI from the boot CPU. Section B.4.2 of the Multi-Processor
# Specification says that the AP will start in real mode with CS:IP
# set to XY00:0000, where XY is an 8-bit value sent with the
# STARTUP. Thus this code must start at a 4096-byte boundary.
2006-09-06 19:08:14 +00:00
#
# Because this code sets DS to zero, it must sit
# at an address in the low 2^16 bytes.
#
2011-09-04 19:56:16 +00:00
# Startothers (in main.c) sends the STARTUPs one at a time.
2011-09-01 14:25:20 +00:00
# It copies this code (start) at 0x7000. It puts the address of
# a newly allocated per-core stack in start-4,the address of the
# place to jump to (mpenter) in start-8, and the physical address
2011-09-04 19:56:16 +00:00
# of entrypgdir in start-12.
#
2016-08-10 15:35:28 +00:00
# This code combines elements of bootasm.S and entry.S.
.code16
.globl start
start:
cli
2016-08-10 15:35:28 +00:00
# Zero data segment registers DS, ES, and SS.
xorw %ax,%ax
movw %ax,%ds
movw %ax,%es
movw %ax,%ss
2016-08-10 15:35:28 +00:00
# Switch from real to protected mode. Use a bootstrap GDT that makes
# virtual addresses map directly to physical addresses so that the
# effective memory map doesn't change during the transition.
lgdt gdtdesc
movl %cr0, %eax
2009-07-12 02:15:32 +00:00
orl $CR0_PE, %eax
movl %eax, %cr0
2006-09-06 19:08:14 +00:00
2016-08-10 15:35:28 +00:00
# Complete the transition to 32-bit protected mode by using a long jmp
# to reload %cs and %eip. The segment descriptors are set up with no
# translation, so that the mapping is still the identity mapping.
ljmpl $(SEG_KCODE<<3), $(start32)
2016-08-10 16:06:02 +00:00
//PAGEBREAK!
2016-08-10 15:35:28 +00:00
.code32 # Tell assembler to generate 32-bit code now.
start32:
2016-08-10 15:35:28 +00:00
# Set up the protected-mode data segment registers
movw $(SEG_KDATA<<3), %ax # Our data segment selector
movw %ax, %ds # -> DS: Data Segment
movw %ax, %es # -> ES: Extra Segment
movw %ax, %ss # -> SS: Stack Segment
movw $0, %ax # Zero segments not ready for use
movw %ax, %fs # -> FS
movw %ax, %gs # -> GS
2011-08-15 21:41:58 +00:00
# Turn on page size extension for 4Mbyte pages
movl %cr4, %eax
orl $(CR4_PSE), %eax
movl %eax, %cr4
# Use entrypgdir as our initial page table
movl (start-12), %eax
movl %eax, %cr3
# Turn on paging.
movl %cr0, %eax
orl $(CR0_PE|CR0_PG|CR0_WP), %eax
movl %eax, %cr0
2011-08-16 00:11:13 +00:00
# Switch to the stack allocated by startothers()
movl (start-4), %esp
2011-08-16 00:11:13 +00:00
# Call mpenter()
call *(start-8)
movw $0x8a00, %ax
movw %ax, %dx
outw %ax, %dx
movw $0x8ae0, %ax
outw %ax, %dx
spin:
jmp spin
2006-09-06 17:27:19 +00:00
.p2align 2
gdt:
SEG_NULLASM
SEG_ASM(STA_X|STA_R, 0, 0xffffffff)
SEG_ASM(STA_W, 0, 0xffffffff)
2006-09-06 17:27:19 +00:00
gdtdesc:
.word (gdtdesc - gdt - 1)
.long gdt