kdump: add vmlist.addr to vmcoreinfo for x86 vmalloc translation.

Add the symbols 'vmlist' and offset 'vm_struct.addr' to the vmcoreinfo[1]
data for i386 vmalloc translation.

makedumpfile[2] needs VMALLOC_START value for distinguishing a vmalloc
address or not, because it should choose suitable translation method.  If
applying this patch, makedumpfile will be able to take VMALLOC_START value
from 'vmlist.addr'.

vmcoreinfo[1]:
The vmcoreinfo data has the minimum debugging information only for dump
filtering. makedumpfile[2] uses it to distinguish unnecessary pages and
creates a small dumpfile.

makedumpfile[2]:
dump filtering command
https://sourceforge.net/projects/makedumpfile/

Signed-off-by: Ken'ichi Ohmichi <oomichi@mxs.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/kexec.c

@@ -1371,6 +1371,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_SYMBOL(node_online_map);
 	VMCOREINFO_SYMBOL(swapper_pg_dir);
 	VMCOREINFO_SYMBOL(_stext);
+	VMCOREINFO_SYMBOL(vmlist);
 
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 	VMCOREINFO_SYMBOL(mem_map);
@@ -1406,6 +1407,7 @@ static int __init crash_save_vmcoreinfo_init(void)
 	VMCOREINFO_OFFSET(free_area, free_list);
 	VMCOREINFO_OFFSET(list_head, next);
 	VMCOREINFO_OFFSET(list_head, prev);
+	VMCOREINFO_OFFSET(vm_struct, addr);
 	VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
 	VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
 	VMCOREINFO_NUMBER(NR_FREE_PAGES);