Re: [PATCH v3 12/13] s390/kexec: refactor for kernel/Kconfig.kexec

Eric DeVolder
2023-06-30T14:35:07Z

On 6/30/23 08:07, Alexander Gordeev wrote:
> On Mon, Jun 26, 2023 at 12:13:31PM -0400, Eric DeVolder wrote:
>> The kexec and crash kernel options are provided in the common
>> kernel/Kconfig.kexec. Utilize the common options and provide
>> the ARCH_SUPPORTS_ and ARCH_SELECTS_ entries to recreate the
>> equivalent set of KEXEC and CRASH options.
>>
>> NOTE: The original Kconfig has a KEXEC_SIG which depends on
>> MODULE_SIG_FORMAT. However, attempts to keep the MODULE_SIG_FORMAT
>> dependency (using the strategy outlined in this series, and other
>> techniques) results in 'error: recursive dependency detected'
>> on CRYPTO.
>>
>> Per Alexander Gordeev <agordeev@linux.ibm.com>: "the MODULE_SIG_FORMAT
>> dependency was introduced with [git commit below] and in fact was not
>> necessary, since s390 did/does not use mod_check_sig() anyway.
>>
>> commit c8424e776b09 ("MODSIGN: Export module signature definitions")
>>
>> MODULE_SIG_FORMAT is needed to select SYSTEM_DATA_VERIFICATION. But
>> SYSTEM_DATA_VERIFICATION is also selected by FS_VERITY*, so dropping
>> MODULE_SIG_FORMAT does not hurt."
>>
>> Therefore, the solution is to drop the MODULE_SIG_FORMAT dependency
>> from KEXEC_SIG. Still results in equivalent .config files for s390.
>>
>> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
>> ---
>> arch/s390/Kconfig | 65 ++++++++++++++---------------------------------
>> 1 file changed, 19 insertions(+), 46 deletions(-)
>>
>> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
>> index 6dab9c1be508..58dc124433ca 100644
>> --- a/arch/s390/Kconfig
>> +++ b/arch/s390/Kconfig
>> @@ -243,6 +243,25 @@ config PGTABLE_LEVELS
>>
>> source "kernel/livepatch/Kconfig"
>>
>> +config ARCH_DEFAULT_KEXEC
>> + def_bool y
>> +
>> +config ARCH_SUPPORTS_KEXEC
>> + def_bool y
>> +
>> +config ARCH_SUPPORTS_KEXEC_FILE
>> + def_bool CRYPTO && CRYPTO_SHA256 && CRYPTO_SHA256_S390
>> +
>> +config ARCH_HAS_KEXEC_PURGATORY
>> + def_bool KEXEC_FILE
>> +
>> +config ARCH_SUPPORTS_CRASH_DUMP
>> + def_bool y
>> + help
>> + Refer to <file:Documentation/s390/zfcpdump.rst> for more details on this.
>> + This option also enables s390 zfcpdump.
>> + See also <file:Documentation/s390/zfcpdump.rst>
>> +
>> menu "Processor type and features"
>>
>> config HAVE_MARCH_Z10_FEATURES
>> @@ -481,36 +500,6 @@ config SCHED_TOPOLOGY
>>
>> source "kernel/Kconfig.hz"
>>
>> -config KEXEC
>> - def_bool y
>> - select KEXEC_CORE
>> -
>> -config KEXEC_FILE
>> - bool "kexec file based system call"
>> - select KEXEC_CORE
>> - depends on CRYPTO
>> - depends on CRYPTO_SHA256
>> - depends on CRYPTO_SHA256_S390
>> - help
>> - Enable the kexec file based system call. In contrast to the normal
>> - kexec system call this system call takes file descriptors for the
>> - kernel and initramfs as arguments.
>> -
>> -config ARCH_HAS_KEXEC_PURGATORY
>> - def_bool y
>> - depends on KEXEC_FILE
>> -
>> -config KEXEC_SIG
>> - bool "Verify kernel signature during kexec_file_load() syscall"
>> - depends on KEXEC_FILE && MODULE_SIG_FORMAT
>> - help
>> - This option makes kernel signature verification mandatory for
>> - the kexec_file_load() syscall.
>> -
>> - In addition to that option, you need to enable signature
>> - verification for the corresponding kernel image type being
>> - loaded in order for this to work.
>> -
>> config KERNEL_NOBP
>> def_bool n
>> prompt "Enable modified branch prediction for the kernel by default"
>> @@ -732,22 +721,6 @@ config VFIO_AP
>>
>> endmenu
>>
>> -menu "Dump support"
>> -
>> -config CRASH_DUMP
>> - bool "kernel crash dumps"
>> - select KEXEC
>> - help
>> - Generate crash dump after being started by kexec.
>> - Crash dump kernels are loaded in the main kernel with kexec-tools
>> - into a specially reserved region and then later executed after
>> - a crash by kdump/kexec.
>> - Refer to <file:Documentation/s390/zfcpdump.rst> for more details on this.
>> - This option also enables s390 zfcpdump.
>> - See also <file:Documentation/s390/zfcpdump.rst>
>> -
>> -endmenu
>> -
>> config CCW
>> def_bool y
>
> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>

Thank you Alexander!
eric