[tip:x86/trampoline] x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline
From: tip-bot for Jarkko Sakkinen
Date: Tue May 08 2012 - 18:32:37 EST
Commit-ID: cda846f101fb1396b6924f1d9b68ac3d42de5403
Gitweb: http://git.kernel.org/tip/cda846f101fb1396b6924f1d9b68ac3d42de5403
Author: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxx>
AuthorDate: Tue, 8 May 2012 21:22:46 +0300
Committer: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
CommitDate: Tue, 8 May 2012 15:04:27 -0700
x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline
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@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1336501366-28617-24-git-send-email-jarkko.sakkinen@xxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/processor.h | 7 +++++-
arch/x86/include/asm/realmode.h | 8 +++++-
arch/x86/kernel/realmode.c | 8 +++++++
arch/x86/kernel/setup.c | 2 +
arch/x86/realmode/rm/header.S | 1 +
arch/x86/realmode/rm/trampoline_64.S | 32 ++++++-----------------------
arch/x86/realmode/rm/trampoline_common.S | 19 +++++++++++++++++
7 files changed, 49 insertions(+), 28 deletions(-)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4fa7dcc..404583c 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -544,13 +544,16 @@ static inline void load_sp0(struct tss_struct *tss,
* enable), so that any CPU's that boot up
* after us can get the correct flags.
*/
-extern unsigned long mmu_cr4_features;
+extern unsigned long mmu_cr4_features;
+extern u32 *trampoline_cr4_features;
static inline void set_in_cr4(unsigned long mask)
{
unsigned long cr4;
mmu_cr4_features |= mask;
+ if (trampoline_cr4_features)
+ *trampoline_cr4_features = mmu_cr4_features;
cr4 = read_cr4();
cr4 |= mask;
write_cr4(cr4);
@@ -561,6 +564,8 @@ static inline void clear_in_cr4(unsigned long mask)
unsigned long cr4;
mmu_cr4_features &= ~mask;
+ if (trampoline_cr4_features)
+ *trampoline_cr4_features = mmu_cr4_features;
cr4 = read_cr4();
cr4 &= ~mask;
write_cr4(cr4);
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index 1421eed..937dc60 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -24,18 +24,22 @@ struct real_mode_header {
#ifdef CONFIG_X86_32
u32 machine_real_restart_asm;
#endif
-} __attribute__((__packed__));
+};
/* This must match data at trampoline_32/64.S */
struct trampoline_header {
#ifdef CONFIG_X86_32
u32 start;
+ u16 gdt_pad;
u16 gdt_limit;
u32 gdt_base;
#else
u64 start;
+ u32 cr4;
+ u32 efer_low;
+ u32 efer_high;
#endif
-} __attribute__((__packed__));
+};
extern struct real_mode_header *real_mode_header;
extern unsigned char real_mode_blob_end[];
diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c
index 712fba8..66ac276 100644
--- a/arch/x86/kernel/realmode.c
+++ b/arch/x86/kernel/realmode.c
@@ -6,6 +6,7 @@
#include <asm/realmode.h>
struct real_mode_header *real_mode_header;
+u32 *trampoline_cr4_features;
void __init setup_real_mode(void)
{
@@ -64,7 +65,14 @@ void __init setup_real_mode(void)
trampoline_header->gdt_limit = __BOOT_DS + 7;
trampoline_header->gdt_base = __pa(boot_gdt);
#else
+ if (rdmsr_safe(MSR_EFER, &trampoline_header->efer_low,
+ &trampoline_header->efer_high))
+ BUG();
+
trampoline_header->start = (u64) secondary_startup_64;
+ trampoline_cr4_features = &trampoline_header->cr4;
+ *trampoline_cr4_features = read_cr4();
+
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
trampoline_pgd[0] = __pa(level3_ident_pgt) + _KERNPG_TABLE;
trampoline_pgd[511] = __pa(level3_kernel_pgt) + _KERNPG_TABLE;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 7a14fec..efcf305 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -975,6 +975,8 @@ void __init setup_arch(char **cmdline_p)
if (boot_cpu_data.cpuid_level >= 0) {
/* A CPU has %cr4 if and only if it has CPUID */
mmu_cr4_features = read_cr4();
+ if (trampoline_cr4_features)
+ *trampoline_cr4_features = mmu_cr4_features;
}
#ifdef CONFIG_X86_32
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index b4c3263..4612d53 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -9,6 +9,7 @@
.section ".header", "a"
+ .balign 16
GLOBAL(real_mode_header)
.long pa_text_start
.long pa_ro_end
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
index 3f72932..66e26f0 100644
--- a/arch/x86/realmode/rm/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -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"
diff --git a/arch/x86/realmode/rm/trampoline_common.S b/arch/x86/realmode/rm/trampoline_common.S
index c3f951c..cac444b 100644
--- a/arch/x86/realmode/rm/trampoline_common.S
+++ b/arch/x86/realmode/rm/trampoline_common.S
@@ -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)
--
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