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x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline

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This patch changes 64-bit trampoline so that CR4 and
EFER are provided by the kernel instead of using fixed
values.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-24-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Jarkko Sakkinen
2012-05-08 21:22:46 +03:00
committed by H. Peter Anvin
parent bf8b88e977
commit cda846f101
7 changed files with 49 additions and 28 deletions
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1
arch/x86/realmode/rm/header.S
View File

@@ -9,6 +9,7 @@
.section ".header", "a"
.balign 16
GLOBAL(real_mode_header)
.long pa_text_start
.long pa_ro_end

32
arch/x86/realmode/rm/trampoline_64.S
View File

@@ -34,9 +34,9 @@
#include "realmode.h"
.text
.balign PAGE_SIZE
.code16
.balign PAGE_SIZE
ENTRY(trampoline_start)
cli # We should be safe anyway
wbinvd
@@ -65,8 +65,8 @@ ENTRY(trampoline_start)
* to 32 bit.
*/
lidtl tidt # load idt with 0, 0
lgdtl tgdt # load gdt with whatever is appropriate
lidtl tr_idt # load idt with 0, 0
lgdtl tr_gdt # load gdt with whatever is appropriate
movw $__KERNEL_DS, %dx # Data segment descriptor
@@ -93,16 +93,17 @@ ENTRY(startup_32)
movl %edx, %fs
movl %edx, %gs
movl $X86_CR4_PAE, %eax
movl pa_tr_cr4, %eax
movl %eax, %cr4 # Enable PAE mode
# Setup trampoline 4 level pagetables
movl $pa_trampoline_pgd, %eax
movl %eax, %cr3
# Set up EFER
movl pa_tr_efer, %eax
movl pa_tr_efer + 4, %edx
movl $MSR_EFER, %ecx
movl $((1 << _EFER_LME) | (1 << _EFER_NX)), %eax # Enable Long Mode
xorl %edx, %edx
wrmsr
# Enable paging and in turn activate Long Mode
@@ -124,23 +125,4 @@ ENTRY(startup_64)
# Now jump into the kernel using virtual addresses
jmpq *tr_start(%rip)
.section ".rodata","a"
.balign 16
tidt:
.word 0 # idt limit = 0
.word 0, 0 # idt base = 0L
# Duplicate the global descriptor table
# so the kernel can live anywhere
.balign 16
.globl tgdt
tgdt:
.short tgdt_end - tgdt - 1 # gdt limit
.long pa_tgdt
.short 0
.quad 0x00cf9b000000ffff # __KERNEL32_CS
.quad 0x00af9b000000ffff # __KERNEL_CS
.quad 0x00cf93000000ffff # __KERNEL_DS
tgdt_end:
#include "trampoline_common.S"

19
arch/x86/realmode/rm/trampoline_common.S
View File

@@ -1,5 +1,20 @@
.section ".rodata","a"
#ifdef CONFIG_X86_64
# Duplicate the global descriptor table
# so the kernel can live anywhere
.balign 16
.globl tr_gdt
tr_gdt:
.short tr_gdt_end - tr_gdt - 1 # gdt limit
.long pa_tr_gdt
.short 0
.quad 0x00cf9b000000ffff # __KERNEL32_CS
.quad 0x00af9b000000ffff # __KERNEL_CS
.quad 0x00cf93000000ffff # __KERNEL_DS
tr_gdt_end:
#endif
.balign 4
tr_idt: .fill 1, 6, 0
@@ -8,12 +23,16 @@ tr_idt: .fill 1, 6, 0
.balign 4
GLOBAL(trampoline_status) .space 4
.balign 8
GLOBAL(trampoline_header)
#ifdef CONFIG_X86_32
tr_start: .space 4
tr_gdt_pad: .space 2
tr_gdt: .space 6
#else
tr_start: .space 8
GLOBAL(tr_cr4) .space 4
GLOBAL(tr_efer) .space 8
#endif
END(trampoline_header)