[PATCH v2]x86: Fix override new_cpu_data.x86 with 486

[PATCH v2]x86: Fix override new_cpu_data.x86 with 486

[Wang YanQing]

We should set X86 to 486 before use cpuid
to detect the cpu type, if we set X86 to 486
after cpuid, then we will get 486 until
cpu_detect runs.

Signed-off-by: Wang YanQing <udknight@gmail.com>
---
ChangeLog
v1-v2:
1:Use more accurate and short commit log

 arch/x86/kernel/head_32.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 73afd11..24c6675 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -410,6 +410,7 @@ enable_paging:
 /*
  * Check if it is 486
  */
+	movb $4,X86			# at least 486
 	cmpl $-1,X86_CPUID
 	je is486
 
@@ -437,7 +438,6 @@ enable_paging:
 	movl %edx,X86_CAPABILITY
 
 is486:
-	movb $4,X86
 	movl $0x50022,%ecx	# set AM, WP, NE and MP
 	movl %cr0,%eax
 	andl $0x80000011,%eax	# Save PG,PE,ET
-- 
1.7.12.4.dirty

Re: [PATCH v2]x86: Fix override new_cpu_data.x86 with 486

[Borislav Petkov]

On Fri, Jun 28, 2013 at 10:45:16PM +0800, Wang YanQing wrote:
> We should set X86 to 486 before use cpuid
> to detect the cpu type, if we set X86 to 486
> after cpuid, then we will get 486 until
> cpu_detect runs.
> 
> Signed-off-by: Wang YanQing <udknight@gmail.com>

Acked-by: Borislav Petkov <bp@suse.de>

Since this is not a critical bugfix but a mere correctness issue, and it
is too late for 3.11 anyway, it is most likely going to go straight to
3.12.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

[tip:x86/cpu] x86: Fix override new_cpu_data.x86 with 486

[tip-bot for Wang YanQing]

Commit-ID:  237d1548543312fcc8c99d302ab68fbf8ef6f97f
Gitweb:     http://git.kernel.org/tip/237d1548543312fcc8c99d302ab68fbf8ef6f97f
Author:     Wang YanQing <udknight@gmail.com>
AuthorDate: Fri, 28 Jun 2013 22:45:16 +0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Fri, 28 Jun 2013 15:27:29 -0700

x86: Fix override new_cpu_data.x86 with 486

We should set X86 to 486 before use cpuid to detect the cpu type, if
we set X86 to 486 after cpuid, then we will get 486 until cpu_detect
runs.

Signed-off-by: Wang YanQing <udknight@gmail.com>
Link: http://lkml.kernel.org/r/20130628144516.GA2177@udknight
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 arch/x86/kernel/head_32.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index e65ddc6..fe79573 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -410,6 +410,7 @@ enable_paging:
 /*
  * Check if it is 486
  */
+	movb $4,X86			# at least 486
 	cmpl $-1,X86_CPUID
 	je is486
 
@@ -437,7 +438,6 @@ enable_paging:
 	movl %edx,X86_CAPABILITY
 
 is486:
-	movb $4,X86
 	movl $0x50022,%ecx	# set AM, WP, NE and MP
 	movl %cr0,%eax
 	andl $0x80000011,%eax	# Save PG,PE,ET