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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2013 Google Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; version 2 of
* the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
/* The SIPI vector is responsible for initializing the APs in the sytem. It
* loads microcode, sets up MSRs, and enables caching before calling into
* C code. */
/* These segment selectors need to match the gdt entries in c_start.S. */
#define CODE_SEG 0x10
#define DATA_SEG 0x18
#define IA32_UPDT_TRIG 0x79
#define IA32_BIOS_SIGN_ID 0x8b
.section ".module_parameters", "aw", @progbits
ap_start_params:
gdtaddr:
.word 0 /* limit */
.long 0 /* table */
.word 0 /* unused */
idt_ptr:
.long 0
stack_top:
.long 0
stack_size:
.long 0
microcode_lock:
.long 0
microcode_ptr:
.long 0
msr_table_ptr:
.long 0
msr_count:
.long 0
c_handler:
.long 0
ap_count:
.long 0
.text
.code16
.global _start
_start:
cli
xorl %eax, %eax
movl %eax, %cr3 /* Invalidate TLB*/
/* On hyper threaded cpus, invalidating the cache here is
* very very bad. Don't.
*/
/* setup the data segment */
movw %cs, %ax
movw %ax, %ds
/* The gdtaddr needs to be releative to the data segment in order
* to properly dereference it. The .text section comes first in an
* rmodule so _start can be used as a proxy for the load address. */
movl $(gdtaddr), %ebx
sub $(_start), %ebx
data32 lgdt (%ebx)
movl %cr0, %eax
andl $0x7FFAFFD1, %eax /* PG,AM,WP,NE,TS,EM,MP = 0 */
orl $0x60000001, %eax /* CD, NW, PE = 1 */
movl %eax, %cr0
ljmpl $CODE_SEG, $1f
1:
.code32
movw $DATA_SEG, %ax
movw %ax, %ds
movw %ax, %es
movw %ax, %ss
movw %ax, %fs
movw %ax, %gs
/* Load the Interrupt descriptor table */
mov idt_ptr, %ebx
lidt (%ebx)
/* Obtain CPU number. */
movl ap_count, %eax
1:
movl %eax, %ecx
inc %ecx
lock cmpxchg %ecx, ap_count
jnz 1b
/* Setup stacks for each CPU. */
movl stack_size, %eax
mul %ecx
movl stack_top, %edx
subl %eax, %edx
mov %edx, %esp
/* Save CPU number. */
mov %ecx, %esi
/* Determine if one should check microcode versions. */
mov microcode_ptr, %edi
test %edi, %edi
jz microcode_done /* Bypass if no microde exists. */
/* Get the Microcode version. */
mov $1, %eax
cpuid
mov $IA32_BIOS_SIGN_ID, %ecx
rdmsr
/* If something already loaded skip loading again. */
test %edx, %edx
jnz microcode_done
/* Determine if parallel microcode loading is allowed. */
cmp $0xffffffff, microcode_lock
je load_microcode
/* Protect microcode loading. */
lock_microcode:
lock bts $0, microcode_lock
jc lock_microcode
load_microcode:
/* Load new microcode. */
mov $IA32_UPDT_TRIG, %ecx
xor %edx, %edx
mov %edi, %eax
/* The microcode pointer is passed in pointing to the header. Adjust
* pointer to reflect the payload (header size is 48 bytes). */
add $48, %eax
pusha
wrmsr
popa
/* Unconditionally unlock microcode loading. */
cmp $0xffffffff, microcode_lock
je microcode_done
xor %eax, %eax
mov %eax, microcode_lock
microcode_done:
/*
* Load MSRs. Each entry in the table consists of:
* 0: index,
* 4: value[31:0]
* 8: value[63:32]
*/
mov msr_table_ptr, %edi
mov msr_count, %ebx
test %ebx, %ebx
jz 1f
load_msr:
mov (%edi), %ecx
mov 4(%edi), %eax
mov 8(%edi), %edx
wrmsr
add $12, %edi
dec %ebx
jnz load_msr
1:
/* Enable caching. */
mov %cr0, %eax
and $0x9fffffff, %eax /* CD, NW = 0 */
mov %eax, %cr0
/* c_handler(cpu_num) */
push %esi /* cpu_num */
mov c_handler, %eax
call *%eax
halt_jump:
hlt
jmp halt_jump
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