Messages in this thread | | | Date | Wed, 25 May 2022 19:56:39 +0530 | Subject | Re: [PATCH v8 7/7] x86/crash: Add x86 crash hotplug support for kexec_load | From | Sourabh Jain <> |
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Hello Eric,
On 06/05/22 00:16, Eric DeVolder wrote: > For kexec_file_load support, the loading of the crash kernel occurs > entirely within the kernel, and as such the elfcorehdr is readily > identified (so that it can be modified upon hotplug events). > > This change enables support for kexec_load by identifying the > elfcorehdr segment in the arch_crash_handle_hotplug_event(), > if it has not already been identified. > > Signed-off-by: Eric DeVolder <eric.devolder@oracle.com> > Acked-by: Baoquan He <bhe@redhat.com> > --- > arch/x86/kernel/crash.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index 951ef365f0a7..845d7c77854d 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -485,6 +485,30 @@ void arch_crash_handle_hotplug_event(struct kimage *image, > void *elfbuf = NULL; > unsigned long mem, memsz; > > + /* > + * When the struct kimage is alloced, it is wiped to zero, so > + * the elfcorehdr_index_valid defaults to false. It is set on the > + * kexec_file_load path, or here for kexec_load, if not already > + * identified. > + */ > + if (!image->elfcorehdr_index_valid) { > + unsigned int n; > + > + for (n = 0; n < image->nr_segments; n++) { > + mem = image->segment[n].mem; > + memsz = image->segment[n].memsz; > + ptr = map_crash_pages(mem, memsz); > + if (ptr) { > + /* The segment containing elfcorehdr */ > + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { > + image->elfcorehdr_index = (int)n; > + image->elfcorehdr_index_valid = true;
How about finding elfcorehdr index on kexec_load path post kimage_load_segment call in do_kexec_load (kernel/kexec.c) or other suitable place? This way we can avoid checking for elfcorehdr index for every hotplug. Also we might not need image->elfcorehdr_index_valid.
Thanks, Sourabh Jain
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