dccf78d39f
Ignat Korchagin complained that a potential config regression was introduced by commit89cde45591("kexec: consolidate kexec and crash options into kernel/Kconfig.kexec"). Before the commit, CONFIG_CRASH_DUMP has no dependency on CONFIG_KEXEC. After the commit, CRASH_DUMP selects KEXEC. That enforces system to have CONFIG_KEXEC=y as long as CONFIG_CRASH_DUMP=Y which people may not want. In Ignat's case, he sets CONFIG_CRASH_DUMP=y, CONFIG_KEXEC_FILE=y and CONFIG_KEXEC=n because kexec_load interface could have security issue if kernel/initrd has no chance to be signed and verified. CRASH_DUMP has select of KEXEC because Eric, author of above commit, met a LKP report of build failure when posting patch of earlier version. Please see below link to get detail of the LKP report: https://lore.kernel.org/all/3e8eecd1-a277-2cfb-690e-5de2eb7b988e@oracle.com/T/#u In fact, that LKP report is triggered because arm's <asm/kexec.h> is wrapped in CONFIG_KEXEC ifdeffery scope. That is wrong. CONFIG_KEXEC controls the enabling/disabling of kexec_load interface, but not kexec feature. Removing the wrongly added CONFIG_KEXEC ifdeffery scope in <asm/kexec.h> of arm allows us to drop the select KEXEC for CRASH_DUMP. Meanwhile, change arch/arm/kernel/Makefile to let machine_kexec.o relocate_kernel.o depend on KEXEC_CORE. Link: https://lkml.kernel.org/r/20231128054457.659452-1-bhe@redhat.com Fixes:89cde45591("kexec: consolidate kexec and crash options into kernel/Kconfig.kexec") Signed-off-by: Baoquan He <bhe@redhat.com> Reported-by: Ignat Korchagin <ignat@cloudflare.com> Tested-by: Ignat Korchagin <ignat@cloudflare.com> [compile-time only] Tested-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Eric DeVolder <eric_devolder@yahoo.com> Tested-by: Eric DeVolder <eric_devolder@yahoo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
150 lines
5.1 KiB
Plaintext
150 lines
5.1 KiB
Plaintext
# SPDX-License-Identifier: GPL-2.0-only
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menu "Kexec and crash features"
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config CRASH_CORE
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bool
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config KEXEC_CORE
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select CRASH_CORE
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bool
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config KEXEC_ELF
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bool
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config HAVE_IMA_KEXEC
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bool
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config KEXEC
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bool "Enable kexec system call"
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depends on ARCH_SUPPORTS_KEXEC
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select KEXEC_CORE
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help
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kexec is a system call that implements the ability to shutdown your
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current kernel, and to start another kernel. It is like a reboot
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but it is independent of the system firmware. And like a reboot
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you can start any kernel with it, not just Linux.
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The name comes from the similarity to the exec system call.
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It is an ongoing process to be certain the hardware in a machine
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is properly shutdown, so do not be surprised if this code does not
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initially work for you. As of this writing the exact hardware
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interface is strongly in flux, so no good recommendation can be
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made.
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config KEXEC_FILE
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bool "Enable kexec file based system call"
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depends on ARCH_SUPPORTS_KEXEC_FILE
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select KEXEC_CORE
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help
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This is new version of kexec system call. This system call is
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file based and takes file descriptors as system call argument
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for kernel and initramfs as opposed to list of segments as
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accepted by kexec system call.
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config KEXEC_SIG
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bool "Verify kernel signature during kexec_file_load() syscall"
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depends on ARCH_SUPPORTS_KEXEC_SIG
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depends on KEXEC_FILE
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help
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This option makes the kexec_file_load() syscall check for a valid
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signature of the kernel image. The image can still be loaded without
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a valid signature unless you also enable KEXEC_SIG_FORCE, though if
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there's a signature that we can check, then it must be valid.
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In addition to this option, you need to enable signature
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verification for the corresponding kernel image type being
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loaded in order for this to work.
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config KEXEC_SIG_FORCE
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bool "Require a valid signature in kexec_file_load() syscall"
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depends on ARCH_SUPPORTS_KEXEC_SIG_FORCE
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depends on KEXEC_SIG
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help
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This option makes kernel signature verification mandatory for
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the kexec_file_load() syscall.
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config KEXEC_IMAGE_VERIFY_SIG
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bool "Enable Image signature verification support (ARM)"
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default ARCH_DEFAULT_KEXEC_IMAGE_VERIFY_SIG
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depends on ARCH_SUPPORTS_KEXEC_IMAGE_VERIFY_SIG
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depends on KEXEC_SIG
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depends on EFI && SIGNED_PE_FILE_VERIFICATION
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help
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Enable Image signature verification support.
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config KEXEC_BZIMAGE_VERIFY_SIG
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bool "Enable bzImage signature verification support"
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depends on ARCH_SUPPORTS_KEXEC_BZIMAGE_VERIFY_SIG
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depends on KEXEC_SIG
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depends on SIGNED_PE_FILE_VERIFICATION
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select SYSTEM_TRUSTED_KEYRING
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help
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Enable bzImage signature verification support.
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config KEXEC_JUMP
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bool "kexec jump"
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depends on ARCH_SUPPORTS_KEXEC_JUMP
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depends on KEXEC && HIBERNATION
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help
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Jump between original kernel and kexeced kernel and invoke
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code in physical address mode via KEXEC
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config CRASH_DUMP
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bool "kernel crash dumps"
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depends on ARCH_SUPPORTS_CRASH_DUMP
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depends on ARCH_SUPPORTS_KEXEC
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select CRASH_CORE
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select KEXEC_CORE
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help
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Generate crash dump after being started by kexec.
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This should be normally only set in special crash dump kernels
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which are loaded in the main kernel with kexec-tools into
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a specially reserved region and then later executed after
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a crash by kdump/kexec. The crash dump kernel must be compiled
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to a memory address not used by the main kernel or BIOS using
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PHYSICAL_START, or it must be built as a relocatable image
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(CONFIG_RELOCATABLE=y).
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For more details see Documentation/admin-guide/kdump/kdump.rst
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For s390, this option also enables zfcpdump.
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See also <file:Documentation/arch/s390/zfcpdump.rst>
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config CRASH_HOTPLUG
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bool "Update the crash elfcorehdr on system configuration changes"
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default y
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depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG)
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depends on ARCH_SUPPORTS_CRASH_HOTPLUG
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help
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Enable direct update to the crash elfcorehdr (which contains
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the list of CPUs and memory regions to be dumped upon a crash)
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in response to hot plug/unplug or online/offline of CPUs or
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memory. This is a much more advanced approach than userspace
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attempting that.
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If unsure, say Y.
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config CRASH_MAX_MEMORY_RANGES
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int "Specify the maximum number of memory regions for the elfcorehdr"
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default 8192
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depends on CRASH_HOTPLUG
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help
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For the kexec_file_load() syscall path, specify the maximum number of
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memory regions that the elfcorehdr buffer/segment can accommodate.
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These regions are obtained via walk_system_ram_res(); eg. the
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'System RAM' entries in /proc/iomem.
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This value is combined with NR_CPUS_DEFAULT and multiplied by
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sizeof(Elf64_Phdr) to determine the final elfcorehdr memory buffer/
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segment size.
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The value 8192, for example, covers a (sparsely populated) 1TiB system
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consisting of 128MiB memblocks, while resulting in an elfcorehdr
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memory buffer/segment size under 1MiB. This represents a sane choice
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to accommodate both baremetal and virtual machine configurations.
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For the kexec_load() syscall path, CRASH_MAX_MEMORY_RANGES is part of
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the computation behind the value provided through the
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/sys/kernel/crash_elfcorehdr_size attribute.
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endmenu
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