Subject: [PATCH v6 01/14] kexec: consolidate kexec and crash options into kernel/Kconfig.kexec

From: Eric DeVolder <[email-masked]>
Date: Wed, 12 Jul 2023 12:15:32 -0400

The config options for kexec and crash features are consolidated
into new file kernel/Kconfig.kexec. Under the "General Setup" submenu
is a new submenu "Kexec and crash handling". All the kexec and
crash options that were once in the arch-dependent submenu "Processor
type and features" are now consolidated in the new submenu.

The following options are impacted:

 - KEXEC
 - KEXEC_FILE
 - KEXEC_SIG
 - KEXEC_SIG_FORCE
 - KEXEC_BZIMAGE_VERIFY_SIG
 - KEXEC_JUMP
 - CRASH_DUMP

The three main options are KEXEC, KEXEC_FILE and CRASH_DUMP.

Architectures specify support of certain KEXEC and CRASH features with
similarly named new ARCH_SUPPORTS_<option> config options.

Architectures can utilize the new ARCH_SELECTS_<option> config
options to specify additional components when <option> is enabled.

To summarize, the ARCH_SUPPORTS_<option> permits the <option> to be
enabled, and the ARCH_SELECTS_<option> handles side effects (ie.
select statements).

Signed-off-by: Eric DeVolder <[email-masked]>
---
 arch/Kconfig         |  13 -----
 init/Kconfig         |   2 +
 kernel/Kconfig.kexec | 116 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 118 insertions(+), 13 deletions(-)
 create mode 100644 kernel/Kconfig.kexec

diff --git a/arch/Kconfig b/arch/Kconfig
index aff2746c8af2..b2872e9d3760 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -11,19 +11,6 @@ source "arch/$(SRCARCH)/Kconfig"
 
 menu "General architecture-dependent options"
 
-config CRASH_CORE
-	bool
-
-config KEXEC_CORE
-	select CRASH_CORE
-	bool
-
-config KEXEC_ELF
-	bool
-
-config HAVE_IMA_KEXEC
-	bool
-
 config ARCH_HAS_SUBPAGE_FAULTS
 	bool
 	help
diff --git a/init/Kconfig b/init/Kconfig
index f7f65af4ee12..639e8a3363c3 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1927,6 +1927,8 @@ config BINDGEN_VERSION_TEXT
 config TRACEPOINTS
 	bool
 
+source "kernel/Kconfig.kexec"
+
 endmenu		# General setup
 
 source "arch/Kconfig"
diff --git a/kernel/Kconfig.kexec b/kernel/Kconfig.kexec
new file mode 100644
index 000000000000..ff72e45cfaef
--- /dev/null
+++ b/kernel/Kconfig.kexec
@@ -0,0 +1,116 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Kexec and crash features"
+
+config CRASH_CORE
+	bool
+
+config KEXEC_CORE
+	select CRASH_CORE
+	bool
+
+config KEXEC_ELF
+	bool
+
+config HAVE_IMA_KEXEC
+	bool
+
+config KEXEC
+	bool "Enable kexec system call"
+	default ARCH_DEFAULT_KEXEC
+	depends on ARCH_SUPPORTS_KEXEC
+	select KEXEC_CORE
+	help
+	  kexec is a system call that implements the ability to shutdown your
+	  current kernel, and to start another kernel. It is like a reboot
+	  but it is independent of the system firmware. And like a reboot
+	  you can start any kernel with it, not just Linux.
+
+	  The name comes from the similarity to the exec system call.
+
+	  It is an ongoing process to be certain the hardware in a machine
+	  is properly shutdown, so do not be surprised if this code does not
+	  initially work for you. As of this writing the exact hardware
+	  interface is strongly in flux, so no good recommendation can be
+	  made.
+
+config KEXEC_FILE
+	bool "Enable kexec file based system call"
+	depends on ARCH_SUPPORTS_KEXEC_FILE
+	select KEXEC_CORE
+	help
+	  This is new version of kexec system call. This system call is
+	  file based and takes file descriptors as system call argument
+	  for kernel and initramfs as opposed to list of segments as
+	  accepted by kexec system call.
+
+config KEXEC_SIG
+	bool "Verify kernel signature during kexec_file_load() syscall"
+	depends on ARCH_SUPPORTS_KEXEC_SIG
+	depends on KEXEC_FILE
+	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
+	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
+	  there's a signature that we can check, then it must be valid.
+
+	  In addition to this option, you need to enable signature
+	  verification for the corresponding kernel image type being
+	  loaded in order for this to work.
+
+config KEXEC_SIG_FORCE
+	bool "Require a valid signature in kexec_file_load() syscall"
+	depends on ARCH_SUPPORTS_KEXEC_SIG_FORCE
+	depends on KEXEC_SIG
+	help
+	  This option makes kernel signature verification mandatory for
+	  the kexec_file_load() syscall.
+
+config KEXEC_IMAGE_VERIFY_SIG
+	bool "Enable Image signature verification support (ARM)"
+	default ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
+	depends on ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG
+	depends on KEXEC_SIG
+	depends on EFI && SIGNED_PE_FILE_VERIFICATION
+	help
+	  Enable Image signature verification support.
+
+config KEXEC_BZIMAGE_VERIFY_SIG
+	bool "Enable bzImage signature verification support"
+	depends on ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
+	depends on KEXEC_SIG
+	depends on SIGNED_PE_FILE_VERIFICATION
+	select SYSTEM_TRUSTED_KEYRING
+	help
+	  Enable bzImage signature verification support.
+
+config KEXEC_JUMP
+	bool "kexec jump"
+	depends on ARCH_SUPPORTS_KEXEC_JUMP
+	depends on KEXEC && HIBERNATION
+	help
+	  Jump between original kernel and kexeced kernel and invoke
+	  code in physical address mode via KEXEC
+
+config CRASH_DUMP
+	bool "kernel crash dumps"
+	depends on ARCH_SUPPORTS_CRASH_DUMP
+	depends on ARCH_SUPPORTS_KEXEC
+	select CRASH_CORE
+	select KEXEC_CORE
+	select KEXEC
+	help
+	  Generate crash dump after being started by kexec.
+	  This should be normally only set in special crash dump kernels
+	  which are loaded in the main kernel with kexec-tools into
+	  a specially reserved region and then later executed after
+	  a crash by kdump/kexec. The crash dump kernel must be compiled
+	  to a memory address not used by the main kernel or BIOS using
+	  PHYSICAL_START, or it must be built as a relocatable image
+	  (CONFIG_RELOCATABLE=y).
+	  For more details see Documentation/admin-guide/kdump/kdump.rst
+
+	  For s390, this option also enables zfcpdump.
+	  See also <file:Documentation/s390/zfcpdump.rst>
+
+endmenu
-- 
2.31.1