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entry64.S
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/* entry64.S
*
* Copyright (c) 2013 Brian Swetland
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#define mboot_magic 0x1badb002
#define mboot_flags 0x00010000
.code32
.global mboot_header
.global mboot_entry
mboot_header:
.long mboot_magic
.long mboot_flags
.long (-mboot_magic -mboot_flags) # checksum
.long mboot_load_addr # header_addr
.long mboot_load_addr
.long mboot_load_end
.long mboot_bss_end
.long mboot_entry_addr
mboot_entry:
# zero 4 pages for our bootstrap page tables
xor %eax, %eax
mov $0x1000, %edi
mov $0x5000, %ecx
rep stosb
# P4ML[0] -> 0x2000 (PDPT-A)
mov $(0x2000 | 3), %eax
mov %eax, 0x1000
# P4ML[511] -> 0x3000 (PDPT-B)
mov $(0x3000 | 3), %eax
mov %eax, 0x1FF8
# PDPT-A[0] -> 0x4000 (PD)
mov $(0x4000 | 3), %eax
mov %eax, 0x2000
# PDPT-B[510] -> 0x4000 (PD)
mov $(0x4000 | 3), %eax
mov %eax, 0x3FF0
# PD[0..511] -> 0..1022MB
mov $0x83, %eax
mov $0x4000, %ebx
mov $512, %ecx
ptbl_loop:
mov %eax, (%ebx)
add $0x200000, %eax
add $0x8, %ebx
dec %ecx
jnz ptbl_loop
# Clear ebx for initial processor boot.
# When secondary processors boot, they'll call through
# entry32mp (from entryother), but with a nonzero ebx.
# We'll reuse these bootstrap pagetables and GDT.
xor %ebx, %ebx
.global entry32mp
entry32mp:
# CR3 -> 0x1000 (P4ML)
mov $0x1000, %eax
mov %eax, %cr3
lgdt (gdtr64 - mboot_header + mboot_load_addr)
# Enable PAE - CR4.PAE=1
mov %cr4, %eax
bts $5, %eax
mov %eax, %cr4
# enable long mode - EFER.LME=1
mov $0xc0000080, %ecx
rdmsr
bts $8, %eax
wrmsr
# enable paging
mov %cr0, %eax
bts $31, %eax
mov %eax, %cr0
# shift to 64bit segment
ljmp $8,$(entry64low - mboot_header + mboot_load_addr)
.align 16
gdtr64:
.word gdt64_end - gdt64_begin - 1;
.quad gdt64_begin - mboot_header + mboot_load_addr
.align 16
gdt64_begin:
.long 0x00000000 # 0: null desc
.long 0x00000000
.long 0x00000000 # 1: Code, R/X, Nonconforming
.long 0x00209800
.long 0x00000000 # 2: Data, R/W, Expand Down
.long 0x00009000
gdt64_end:
.align 16
.code64
entry64low:
movq $entry64high, %rax
jmp *%rax
.global _start
_start:
entry64high:
# ensure data segment registers are sane
xor %rax, %rax
mov %ax, %ss
mov %ax, %ds
mov %ax, %es
mov %ax, %fs
mov %ax, %gs
# check to see if we're booting a secondary core
test %ebx, %ebx
jnz entry64mp
# setup initial stack
mov $0xFFFFFFFF80010000, %rax
mov %rax, %rsp
# enter main()
jmp main
.global __deadloop
__deadloop:
# we should never return here...
jmp .
entry64mp:
# obtain kstack from data block before entryother
mov $0x7000, %rax
mov -16(%rax), %rsp
jmp mpenter
.global wrmsr
wrmsr:
mov %rdi, %rcx # arg0 -> msrnum
mov %rsi, %rax # val.low -> eax
shr $32, %rsi
mov %rsi, %rdx # val.high -> edx
wrmsr
retq