diff options
| author | Eric DeVolder <eric.devolder@oracle.com> | 2023-08-15 00:44:46 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-08-25 02:25:15 +0300 |
| commit | 543cd4c5e78b15def9d7e8626d7592cb3097f75e (patch) | |
| tree | 15decfce179c14c6c23ee6fd3ec2de3e7e0676d2 /arch/x86 | |
| parent | a396d0f81b1c81b1fa60b5554b5c0e3cea1f27c0 (diff) | |
| download | linux-543cd4c5e78b15def9d7e8626d7592cb3097f75e.tar.xz | |
x86/crash: optimize CPU changes
crash_prepare_elf64_headers() writes into the elfcorehdr an ELF PT_NOTE
for all possible CPUs. As such, subsequent changes to CPUs (ie. hot
un/plug, online/offline) do not need to rewrite the elfcorehdr.
The kimage->file_mode term covers kdump images loaded via the
kexec_file_load() syscall. Since crash_prepare_elf64_headers() wrote the
initial elfcorehdr, no update to the elfcorehdr is needed for CPU changes.
The kimage->elfcorehdr_updated term covers kdump images loaded via the
kexec_load() syscall. At least one memory or CPU change must occur to
cause crash_prepare_elf64_headers() to rewrite the elfcorehdr.
Afterwards, no update to the elfcorehdr is needed for CPU changes.
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.
Link: https://lkml.kernel.org/r/20230814214446.6659-9-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Akhil Raj <lf32.dev@gmail.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/crash.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 22461ce7044a..587c7743fd21 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -470,6 +470,16 @@ void arch_crash_handle_hotplug_event(struct kimage *image) 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. + */ + 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. */ |