kernel/crash: handle multi-page vmcoreinfo in crash kernel copy

kernel/crash: handle multi-page vmcoreinfo in crash kernel copy

kimage_crash_copy_vmcoreinfo() currently assumes vmcoreinfo fits in a
single page.  This breaks if VMCOREINFO_BYTES exceeds PAGE_SIZE.

Allocate the required order of control pages and vmap all pages needed to
safely copy vmcoreinfo into the crash kernel image.

Link: https://lkml.kernel.org/r/20251216132801.807260-3-pnina.feder@mobileye.com
Signed-off-by: Pnina Feder <pnina.feder@mobileye.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>