Subject: [PATCH v5 12/13] s390/kexec: refactor for kernel/Kconfig.kexec

From: Eric DeVolder <[email-masked]>
Date: Thu, 6 Jul 2023 18:20:26 -0400

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 <[email-masked]>: "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 <[email-masked]>
Acked-by: Alexander Gordeev <[email-masked]>
---
 arch/s390/Kconfig | 69 ++++++++++++++++-------------------------------
 1 file changed, 23 insertions(+), 46 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 5b39918b7042..44154246e4b7 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -213,6 +213,7 @@ config S390
 	select HAVE_VIRT_CPU_ACCOUNTING_IDLE
 	select IOMMU_HELPER		if PCI
 	select IOMMU_SUPPORT		if PCI
+	select KEXEC
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_GATHER_NO_GATHER
 	select MMU_GATHER_RCU_TABLE_FREE
@@ -244,6 +245,28 @@ 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_SUPPORTS_KEXEC_SIG
+	def_bool y
+
+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
@@ -482,36 +505,6 @@ 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"
@@ -733,22 +726,6 @@ 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
 
-- 
2.31.1