Re: [PATCH v1 01/21] kexec: consolidate kexec and crash options into kernel/Kconfig.kexec
From: Eric DeVolder
Date: Wed Jun 14 2023 - 07:55:30 EST
On 6/13/23 20:19, Leizhen (ThunderTown) wrote:
On 2023/6/13 1:27, Eric DeVolder wrote:
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" where all the kexec and
crash options that were once in the arch-dependent submenu "Processor
type and features" are now consolidated.
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_HAS_<option> config options.
Architectures can utilize the new ARCH_SUPPORTS_<option> config
options to specify additional components when <option> is enabled.
To summarize, the ARCH_HAS_<option> permits the <option> to be
enabled, and the ARCH_SUPPORTS_<option> handles side effects (ie.
select statements).
Signed-off-by: Eric DeVolder <eric.devolder@xxxxxxxxxx>
---
arch/Kconfig | 13 ------
init/Kconfig | 2 +
kernel/Kconfig.kexec | 103 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 105 insertions(+), 13 deletions(-)
create mode 100644 kernel/Kconfig.kexec
diff --git a/arch/Kconfig b/arch/Kconfig
index 205fd23e0cad..a37730679730 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 32c24950c4ce..4424447e23a5 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1917,6 +1917,8 @@ 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..660048099865
--- /dev/null
+++ b/kernel/Kconfig.kexec
@@ -0,0 +1,103 @@
+# 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_HAS_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.
"kernel. It is like", "firmware. And like"
A few more spaces, I don't know the original author's intention, perhaps can be removed.
I'll remove the extra spaces.
+
+ 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_HAS_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 previous system call.
+
+config KEXEC_SIG
+ bool "Verify kernel signature during kexec_file_load() syscall"
+ depends on KEXEC_FILE && MODULE_SIG_FORMAT
I see that there is no "depends on MODULE_SIG_FORMAT" on x86 and arm64.
Good catch, I'll remove MODULE_SIG_FORMAT and place it on just s390 (which is the only arch that had
it this way).
+ help
+
This blank line can be deleted.
I will remove it.
Thank you, Zhen!
eric
+ 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 KEXEC_SIG
+ help
+ This option makes kernel signature verification mandatory for
+ the kexec_file_load() syscall.
+
+config KEXEC_BZIMAGE_VERIFY_SIG
+ bool "Enable bzImage signature verification support"
+ 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 KEXEC && HIBERNATION
+ depends on ARCH_HAS_KEXEC_JUMP
+ 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_HAS_CRASH_DUMP
+ select KEXEC_CORE
+ select CRASH_CORE
+ 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