This patch is dependent upon the patch 'crash: change crash_prepare_elf64_headers() to for_each_possible_cpu()'. With that patch, crash_prepare_elf64_headers() writes out an ELF CPU PT_NOTE for all possible CPUs, thus further CPU changes to the elfcorehdr are not needed. This change works for kexec_file_load() and kexec_load() syscalls. For kexec_file_load(), crash_prepare_elf64_headers() is utilized directly and thus all ELF CPU PT_NOTEs are in the elfcorehdr already. This is the kimage->file_mode term. For kexec_load() syscall, one CPU or memory change will cause the elfcorehdr to be updated via crash_prepare_elf64_headers() and at that point all ELF CPU PT_NOTEs are in the elfcorehdr. This is the kimage->elfcorehdr_updated term. This code is intentionally *NOT* hoisted into crash_handle_hotplug_event() as it would prevent the arch-specific handler from running for CPU changes. This would break PPC, for example, which needs to update other information besides the elfcorehdr, on CPU changes. Signed-off-by: Eric DeVolder <eric.devolder@xxxxxxxxxx> Reviewed-by: Sourabh Jain <sourabhjain@xxxxxxxxxxxxx> Acked-by: Baoquan He <bhe@xxxxxxxxxx> --- arch/x86/kernel/crash.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 8064e65de6c0..3157e6068747 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -483,6 +483,16 @@ void arch_crash_handle_hotplug_event(struct kimage *image) unsigned long mem, memsz; unsigned long elfsz = 0; + /* As crash_prepare_elf64_headers() has already described all + * possible CPUs, there is no need to update the elfcorehdr + * for additional CPU changes. This works for both kexec_load() + * and kexec_file_load() syscalls. + */ + if ((image->file_mode || image->elfcorehdr_updated) && + ((image->hp_action == KEXEC_CRASH_HP_ADD_CPU) || + (image->hp_action == KEXEC_CRASH_HP_REMOVE_CPU))) + return; + /* * Create the new elfcorehdr reflecting the changes to CPU and/or * memory resources. -- 2.31.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
