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kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP

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Ignat Korchagin complained that a potential config regression was
introduced by commit 89cde455915f ("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: 89cde455915f ("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>
This commit is contained in:
Baoquan He 2023-11-28 13:44:57 +08:00 committed by Andrew Morton
parent 8e92157d7f
commit dccf78d39f
3 changed files with 1 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/arm/include/asm/kexec.h
View File

@ -2,8 +2,6 @@
#ifndef _ARM_KEXEC_H #ifndef _ARM_KEXEC_H
#define _ARM_KEXEC_H #define _ARM_KEXEC_H
#ifdef CONFIG_KEXEC
/* Maximum physical address we can use pages from */ /* Maximum physical address we can use pages from */
#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL) #define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
/* Maximum address we can reach in physical address mode */ /* Maximum address we can reach in physical address mode */
@ -82,6 +80,4 @@ static inline struct page *boot_pfn_to_page(unsigned long boot_pfn)
#endif /* __ASSEMBLY__ */ #endif /* __ASSEMBLY__ */
#endif /* CONFIG_KEXEC */
#endif /* _ARM_KEXEC_H */ #endif /* _ARM_KEXEC_H */

2
arch/arm/kernel/Makefile
View File

@ -59,7 +59,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += entry-ftrace.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o patch.o obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o patch.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o patch.o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o patch.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o obj-$(CONFIG_KEXEC_CORE) += machine_kexec.o relocate_kernel.o
# Main staffs in KPROBES are in arch/arm/probes/ . # Main staffs in KPROBES are in arch/arm/probes/ .
obj-$(CONFIG_KPROBES) += patch.o insn.o obj-$(CONFIG_KPROBES) += patch.o insn.o
obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o

1
kernel/Kconfig.kexec
View File

@ -97,7 +97,6 @@ config CRASH_DUMP
depends on ARCH_SUPPORTS_KEXEC depends on ARCH_SUPPORTS_KEXEC
select CRASH_CORE select CRASH_CORE
select KEXEC_CORE select KEXEC_CORE
select KEXEC
help help
Generate crash dump after being started by kexec. Generate crash dump after being started by kexec.
This should be normally only set in special crash dump kernels This should be normally only set in special crash dump kernels