[RESEND PATCH v1 1/1] s390/kexec: Make KEXEC_SIG available when CONFIG_MODULES=n

[RESEND PATCH v1 1/1] s390/kexec: Make KEXEC_SIG available when CONFIG_MODULES=n

[Alexander Egorenkov]

The commit c8424e776b09 ("MODSIGN: Export module signature definitions")
replaced the dependency of KEXEC_SIG on SYSTEM_DATA_VERIFICATION with
the dependency on MODULE_SIG_FORMAT. This change disables KEXEC_SIG
in s390 kernels built with MODULES=n if nothing else selects
MODULE_SIG_FORMAT.

Furthermore, the signature verification in s390 kexec does not require
MODULE_SIG_FORMAT because it requires only the struct module_signature and,
therefore, does not depend on code in kernel/module_signature.c.

But making ARCH_SUPPORTS_KEXEC_SIG depend on SYSTEM_DATA_VERIFICATION
is also incorrect because it makes KEXEC_SIG available on s390 only
if some other arbitrary option (for instance a file system or device driver)
selects it directly or indirectly.

To properly make KEXEC_SIG available for s390 kernels built with MODULES=y
as well as MODULES=n _and_ also not depend on arbitrary options selecting
SYSTEM_DATA_VERIFICATION, we set ARCH_SUPPORTS_KEXEC_SIG=y for s390 and
select SYSTEM_DATA_VERIFICATION when KEXEC_SIG=y.

Fixes: c8424e776b09 ("MODSIGN: Export module signature definitions")
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
---
 arch/s390/Kconfig    | 2 +-
 kernel/Kconfig.kexec | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index c2c7bf974397..385c1052cf45 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -313,7 +313,7 @@ config ARCH_SUPPORTS_KEXEC_FILE
 	def_bool y
 
 config ARCH_SUPPORTS_KEXEC_SIG
-	def_bool MODULE_SIG_FORMAT
+	def_bool y
 
 config ARCH_SUPPORTS_KEXEC_PURGATORY
 	def_bool y
diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
index 15632358bcf7..df97227cfca9 100644
--- a/kernel/Kconfig.kexec
+++ b/kernel/Kconfig.kexec
@@ -50,6 +50,7 @@ config KEXEC_SIG
 	bool "Verify kernel signature during kexec_file_load() syscall"
 	depends on ARCH_SUPPORTS_KEXEC_SIG
 	depends on KEXEC_FILE
+	select SYSTEM_DATA_VERIFICATION if S390
 	help
 	  This option makes the kexec_file_load() syscall check for a valid
 	  signature of the kernel image. The image can still be loaded without
-- 
2.51.0

Re: [RESEND PATCH v1 1/1] s390/kexec: Make KEXEC_SIG available when CONFIG_MODULES=n

[Baoquan He]

On 02/09/26 at 02:33pm, Alexander Egorenkov wrote:
> The commit c8424e776b09 ("MODSIGN: Export module signature definitions")
> replaced the dependency of KEXEC_SIG on SYSTEM_DATA_VERIFICATION with
> the dependency on MODULE_SIG_FORMAT. This change disables KEXEC_SIG
> in s390 kernels built with MODULES=n if nothing else selects
> MODULE_SIG_FORMAT.
> 
> Furthermore, the signature verification in s390 kexec does not require
> MODULE_SIG_FORMAT because it requires only the struct module_signature and,
> therefore, does not depend on code in kernel/module_signature.c.
> 
> But making ARCH_SUPPORTS_KEXEC_SIG depend on SYSTEM_DATA_VERIFICATION
> is also incorrect because it makes KEXEC_SIG available on s390 only
> if some other arbitrary option (for instance a file system or device driver)
> selects it directly or indirectly.
> 
> To properly make KEXEC_SIG available for s390 kernels built with MODULES=y
> as well as MODULES=n _and_ also not depend on arbitrary options selecting
> SYSTEM_DATA_VERIFICATION, we set ARCH_SUPPORTS_KEXEC_SIG=y for s390 and
> select SYSTEM_DATA_VERIFICATION when KEXEC_SIG=y.

Thanks for fixing the issue.

Seems the background and change is a little twisting, and selecting
SYSTEM_DATA_VERIFICATION will cause a bunch of verification feature
selected. While the change is only s390 related, request s390 expert to
have look at this change. If no concern from s390 developer, I am also
fine to it.

Thanks
Baoquan
> 
> Fixes: c8424e776b09 ("MODSIGN: Export module signature definitions")
> Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
> ---
>  arch/s390/Kconfig    | 2 +-
>  kernel/Kconfig.kexec | 1 +
>  2 files changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index c2c7bf974397..385c1052cf45 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -313,7 +313,7 @@ config ARCH_SUPPORTS_KEXEC_FILE
>  	def_bool y
>  
>  config ARCH_SUPPORTS_KEXEC_SIG
> -	def_bool MODULE_SIG_FORMAT
> +	def_bool y
>  
>  config ARCH_SUPPORTS_KEXEC_PURGATORY
>  	def_bool y
> diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
> index 15632358bcf7..df97227cfca9 100644
> --- a/kernel/Kconfig.kexec
> +++ b/kernel/Kconfig.kexec
> @@ -50,6 +50,7 @@ config KEXEC_SIG
>  	bool "Verify kernel signature during kexec_file_load() syscall"
>  	depends on ARCH_SUPPORTS_KEXEC_SIG
>  	depends on KEXEC_FILE
> +	select SYSTEM_DATA_VERIFICATION if S390
>  	help
>  	  This option makes the kexec_file_load() syscall check for a valid
>  	  signature of the kernel image. The image can still be loaded without
> -- 
> 2.51.0
> 

Re: [RESEND PATCH v1 1/1] s390/kexec: Make KEXEC_SIG available when CONFIG_MODULES=n

[Heiko Carstens]

On Tue, Feb 10, 2026 at 10:23:01AM +0800, Baoquan He wrote:
> On 02/09/26 at 02:33pm, Alexander Egorenkov wrote:
> > The commit c8424e776b09 ("MODSIGN: Export module signature definitions")
> > replaced the dependency of KEXEC_SIG on SYSTEM_DATA_VERIFICATION with
> > the dependency on MODULE_SIG_FORMAT. This change disables KEXEC_SIG
> > in s390 kernels built with MODULES=n if nothing else selects
> > MODULE_SIG_FORMAT.
> > 
> > Furthermore, the signature verification in s390 kexec does not require
> > MODULE_SIG_FORMAT because it requires only the struct module_signature and,
> > therefore, does not depend on code in kernel/module_signature.c.
> > 
> > But making ARCH_SUPPORTS_KEXEC_SIG depend on SYSTEM_DATA_VERIFICATION
> > is also incorrect because it makes KEXEC_SIG available on s390 only
> > if some other arbitrary option (for instance a file system or device driver)
> > selects it directly or indirectly.
> > 
> > To properly make KEXEC_SIG available for s390 kernels built with MODULES=y
> > as well as MODULES=n _and_ also not depend on arbitrary options selecting
> > SYSTEM_DATA_VERIFICATION, we set ARCH_SUPPORTS_KEXEC_SIG=y for s390 and
> > select SYSTEM_DATA_VERIFICATION when KEXEC_SIG=y.
> 
> Thanks for fixing the issue.
> 
> Seems the background and change is a little twisting, and selecting
> SYSTEM_DATA_VERIFICATION will cause a bunch of verification feature
> selected. While the change is only s390 related, request s390 expert to
> have look at this change. If no concern from s390 developer, I am also
> fine to it.

...

> > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> > index c2c7bf974397..385c1052cf45 100644
> > --- a/arch/s390/Kconfig
> > +++ b/arch/s390/Kconfig
> > @@ -313,7 +313,7 @@ config ARCH_SUPPORTS_KEXEC_FILE
> >  	def_bool y
> >  
> >  config ARCH_SUPPORTS_KEXEC_SIG
> > -	def_bool MODULE_SIG_FORMAT
> > +	def_bool y
> >  
> >  config ARCH_SUPPORTS_KEXEC_PURGATORY
> >  	def_bool y
> > diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
> > index 15632358bcf7..df97227cfca9 100644
> > --- a/kernel/Kconfig.kexec
> > +++ b/kernel/Kconfig.kexec
> > @@ -50,6 +50,7 @@ config KEXEC_SIG
> >  	bool "Verify kernel signature during kexec_file_load() syscall"
> >  	depends on ARCH_SUPPORTS_KEXEC_SIG
> >  	depends on KEXEC_FILE
> > +	select SYSTEM_DATA_VERIFICATION if S390

Alexander, would it make sense to move this to arch/s390/Kconfig and
add something like

	select SYSTEM_DATA_VERIFICATION if KEXEC_SIG

instead? This would have the slight advantage to keep arch specifics
out of common code Kconfig.

Re: [RESEND PATCH v1 1/1] s390/kexec: Make KEXEC_SIG available when CONFIG_MODULES=n

[Alexander Egorenkov]

>> > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
>> > index c2c7bf974397..385c1052cf45 100644
>> > --- a/arch/s390/Kconfig
>> > +++ b/arch/s390/Kconfig
>> > @@ -313,7 +313,7 @@ config ARCH_SUPPORTS_KEXEC_FILE
>> >  	def_bool y
>> >  
>> >  config ARCH_SUPPORTS_KEXEC_SIG
>> > -	def_bool MODULE_SIG_FORMAT
>> > +	def_bool y
>> >  
>> >  config ARCH_SUPPORTS_KEXEC_PURGATORY
>> >  	def_bool y
>> > diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
>> > index 15632358bcf7..df97227cfca9 100644
>> > --- a/kernel/Kconfig.kexec
>> > +++ b/kernel/Kconfig.kexec
>> > @@ -50,6 +50,7 @@ config KEXEC_SIG
>> >  	bool "Verify kernel signature during kexec_file_load() syscall"
>> >  	depends on ARCH_SUPPORTS_KEXEC_SIG
>> >  	depends on KEXEC_FILE
>> > +	select SYSTEM_DATA_VERIFICATION if S390
>
> Alexander, would it make sense to move this to arch/s390/Kconfig and
> add something like
>
> 	select SYSTEM_DATA_VERIFICATION if KEXEC_SIG
>
> instead? This would have the slight advantage to keep arch specifics
> out of common code Kconfig.

That's even better, what i was actually looking for.
And works as expected too.

Thanks, Heiko.