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    Subject[PATCH v11 4/7] kexec: exclude elfcorehdr from the segment digest
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    When a crash kernel is loaded via the kexec_file_load syscall, the
    kernel places the various segments (ie crash kernel, crash initrd,
    boot_params, elfcorehdr, purgatory, etc) in memory. For those
    architectures that utilize purgatory, a hash digest of the segments
    is calculated for integrity checking. This digest is embedded into
    the purgatory image prior to placing purgatory in memory.

    Since hotplug events cause changes to the elfcorehdr, purgatory
    integrity checking fails (at crash time, and no kdump created).
    As a result, this change explicitly excludes the elfcorehdr segment
    from the list of segments used to create the digest. By doing so,
    this permits changes to the elfcorehdr in response to hotplug events,
    without having to also reload purgatory due to the change to the
    digest.

    Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
    Acked-by: Baoquan He <bhe@redhat.com>
    ---
    kernel/kexec_file.c | 6 ++++++
    1 file changed, 6 insertions(+)

    diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
    index 8017eeb43036..d0c2661b3509 100644
    --- a/kernel/kexec_file.c
    +++ b/kernel/kexec_file.c
    @@ -723,6 +723,12 @@ static int kexec_calculate_store_digests(struct kimage *image)
    for (j = i = 0; i < image->nr_segments; i++) {
    struct kexec_segment *ksegment;

    +#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
    + /* Exclude elfcorehdr segment to allow future changes via hotplug */
    + if (image->elfcorehdr_index_valid && (j == image->elfcorehdr_index))
    + continue;
    +#endif
    +
    ksegment = &image->segment[i];
    /*
    * Skip purgatory as it will be modified once we put digest
    --
    2.31.1
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