[PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Tony W Wang-oc]

While the UMIP (User-Mode Instruction Prevention) is a generic X86 CPU
feature, there is no need to tie X86_UMIP only to Intel and AMD.

So remove that dependency from the Kconfig rules.

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
---
 arch/x86/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5ad3957..ca16b762 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1871,7 +1871,6 @@ config X86_SMAP
 
 config X86_UMIP
 	def_bool y
-	depends on CPU_SUP_INTEL || CPU_SUP_AMD
 	prompt "User Mode Instruction Prevention" if EXPERT
 	---help---
 	  User Mode Instruction Prevention (UMIP) is a security feature in
-- 
2.7.4

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Borislav Petkov]

On Mon, Mar 09, 2020 at 02:06:30PM +0800, Tony W Wang-oc wrote:
> While the UMIP (User-Mode Instruction Prevention) is a generic X86 CPU
> feature, there is no need to tie X86_UMIP only to Intel and AMD.

It is not generic - it just lost the "INTEL" in its name.

> So remove that dependency from the Kconfig rules.
> 
> Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
> ---
>  arch/x86/Kconfig | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 5ad3957..ca16b762 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1871,7 +1871,6 @@ config X86_SMAP
>  
>  config X86_UMIP
>  	def_bool y
> -	depends on CPU_SUP_INTEL || CPU_SUP_AMD
>  	prompt "User Mode Instruction Prevention" if EXPERT
>  	---help---
>  	  User Mode Instruction Prevention (UMIP) is a security feature in
> -- 

If you're going to do that, is there even any use for that config option
at all?

AFAICT, it adds ~1K to kernel text so we might just as well remove the
ifdeffery completely. The code ends up built in in 99% of the cases
anyway...

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[H. Peter Anvin]

On 2020-03-09 13:36, Borislav Petkov wrote:
> 
> If you're going to do that, is there even any use for that config option
> at all?
> 
> AFAICT, it adds ~1K to kernel text so we might just as well remove the
> ifdeffery completely. The code ends up built in in 99% of the cases
> anyway...
> 

Perhaps the super-tiny-embedded kernel guys care? Otherwise it seems
pointless.

In general, once INTEL and AMD is enabled, it is just a matter of time
until other (still existent) vendors add those features, at least for
core features.

	-hpa

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Tony W Wang-oc]

On 10/03/2020 08:25, H. Peter Anvin wrote:
> On 2020-03-09 13:36, Borislav Petkov wrote:
>>
>> If you're going to do that, is there even any use for that config option
>> at all?
>>
>> AFAICT, it adds ~1K to kernel text so we might just as well remove the
>> ifdeffery completely. The code ends up built in in 99% of the cases
>> anyway...
>>
> 
> Perhaps the super-tiny-embedded kernel guys care? Otherwise it seems
> pointless.

Agree, and I think leave this config to some users are meaningful.

Moreover, if remove the X86_UMIP config, a kernel-parameter like
"noumip" may be needed?

Sincerely
TonyWWang-oc

> 
> In general, once INTEL and AMD is enabled, it is just a matter of time
> until other (still existent) vendors add those features, at least for
> core features.
> 
> 	-hpa
> .
> 

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Borislav Petkov]

On Mon, Mar 09, 2020 at 05:25:59PM -0700, H. Peter Anvin wrote:
> Perhaps the super-tiny-embedded kernel guys care? Otherwise it seems
> pointless.

Yeah and I haven't heard anything from them in a while. I guess we can
leave it until someone removes it later.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Borislav Petkov]

On Tue, Mar 10, 2020 at 03:24:37PM +0800, Tony W Wang-oc wrote:
> Moreover, if remove the X86_UMIP config, a kernel-parameter like
> "noumip" may be needed?

Not the same thing. Also, why would one need it? If one did, one would
need it now too.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

[tip: x86/cpu] x86/Kconfig: Drop vendor dependency for X86_UMIP

[tip-bot2 for Tony W Wang-oc]

The following commit has been merged into the x86/cpu branch of tip:

Commit-ID:     bdb04a1abbf92c998f1afb5f00a037f2edaec1f7
Gitweb:        https://git.kernel.org/tip/bdb04a1abbf92c998f1afb5f00a037f2edaec1f7
Author:        Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
AuthorDate:    Mon, 09 Mar 2020 14:06:30 +08:00
Committer:     Borislav Petkov <bp@suse.de>
CommitterDate: Tue, 10 Mar 2020 10:10:53 +01:00

x86/Kconfig: Drop vendor dependency for X86_UMIP

Some Centaur family 7 CPUs and Zhaoxin family 7 CPUs support the UMIP
feature too. The text size growth which UMIP adds is ~1K and distro
kernels enable it anyway so remove the vendor dependency.

 [ bp: Rewrite commit message. ]

Signed-off-by: Tony W Wang-oc <TonyWWang-oc@zhaoxin.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/1583733990-2587-1-git-send-email-TonyWWang-oc@zhaoxin.com
---
 arch/x86/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index beea770..cb3633d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1875,7 +1875,6 @@ config X86_SMAP
 
 config X86_UMIP
 	def_bool y
-	depends on CPU_SUP_INTEL || CPU_SUP_AMD
 	prompt "User Mode Instruction Prevention" if EXPERT
 	---help---
 	  User Mode Instruction Prevention (UMIP) is a security feature in

Re: [PATCH] x86/Kconfig: make X86_UMIP to cover any X86 CPU

[Tony W Wang-oc]

On 10/03/2020 17:09, Borislav Petkov wrote:
> On Tue, Mar 10, 2020 at 03:24:37PM +0800, Tony W Wang-oc wrote:
>> Moreover, if remove the X86_UMIP config, a kernel-parameter like
>> "noumip" may be needed?
> 
> Not the same thing. Also, why would one need it? If one did, one would
> need it now too.
> 
Yes, you are right, thank you point this. Let us focus on X86_UMIP config.

Sincerely
TonyWWang-oc