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/*
* This file is part of the coreboot project.
*
* Copyright 2016 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.
*/
#include <cpu/x86/mtrr.h>
#include <cpu/x86/cr.h>
.section ".module_parameters", "aw", @progbits
/* stack_top indicates the stack to pull MTRR information from. */
stack_top:
.long 0
.long 0
.text
.global _start
_start:
/* chipset_teardown_car() is expected to disable cache-as-ram. */
call chipset_teardown_car
/* Enable caching if not already enabled. */
mov %cr0, %eax
and $(~(CR0_CD | CR0_NW)), %eax
mov %eax, %cr0
/* Ensure cache is clean. */
invd
/* Set up new stack. */
mov stack_top, %esp
/*
* Honor variable MTRR information pushed on the stack with the
* following layout:
*
* Offset: Value
* ...
* 0x14: MTRR mask 0 63:32
* 0x10: MTRR mask 0 31:0
* 0x0c: MTRR base 0 63:32
* 0x08: MTRR base 0 31:0
* 0x04: Number of variable MTRRs to set
* 0x00: Number of variable MTRRs to clear
*/
#if IS_ENABLED(CONFIG_SOC_SETS_MSRS)
push %esp
call soc_set_mtrrs
/* eax: new top_of_stack with setup_stack_and_mtrrs data removed */
movl %eax, %esp
call soc_enable_mtrrs
#else /* CONFIG_SOC_SETS_MSRS */
/* Clear variable MTRRs. */
pop %ebx /* Number to clear */
test %ebx, %ebx
jz 2f
xor %eax, %eax
xor %edx, %edx
mov $(MTRR_PHYS_BASE(0)), %ecx
1:
wrmsr
inc %ecx
wrmsr
inc %ecx
dec %ebx
jnz 1b
2:
/* Set Variable MTRRs based on stack contents. */
pop %ebx /* Number to set. */
test %ebx, %ebx
jz 2f
mov $(MTRR_PHYS_BASE(0)), %ecx
1:
/* Write MTRR base. */
pop %eax
pop %edx
wrmsr
inc %ecx
/* Write MTRR mask. */
pop %eax
pop %edx
wrmsr
inc %ecx
dec %ebx
jnz 1b
2:
/* Enable MTRR. */
mov $(MTRR_DEF_TYPE_MSR), %ecx
rdmsr
/* Make default type uncacheable. */
and $(~(MTRR_DEF_TYPE_MASK)), %eax
or $(MTRR_DEF_TYPE_EN), %eax
wrmsr
#endif /* CONFIG_SOC_SETS_MSRS */
/* Call into main for postcar. */
call main
/* Should never return. */
1:
jmp 1b
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