powerpc/kdump: Adding symbols in vmcoreinfo to facilitate dump filtering

When CONFIG_SPARSEMEM_VMEMMAP option is used in kernel, makedumpfile fails
to filter vmcore dump as it fails to do vmemmap translations. So far
dump filtering on ppc64 never had to deal with vmemmap addresses seperately
as vmemmap regions where mapped in zone normal. But with the inclusion of
CONFIG_SPARSEMEM_VMEMMAP config option in kernel, this vmemmap address
translation support becomes necessary for dump filtering. For vmemmap adress
translation, few kernel symbols are needed by dump filtering tool. This patch
adds those symbols to vmcoreinfo, which a dump filtering tool can use for
filtering the kernel dump. Tested this changes successfully with makedumpfile
tool that supports vmemmap to physical address translation outside zone normal.

[ Removed unneeded #ifdef as suggested by Michael Ellerman --BenH ]
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/pgalloc-64.h

@@ -16,6 +16,7 @@ struct vmemmap_backing {
 	unsigned long phys;
 	unsigned long virt_addr;
 };
+extern struct vmemmap_backing *vmemmap_list;
 
 /*
  * Functions that deal with pagetables that could be at any level of

arch/powerpc/kernel/machine_kexec.c

@@ -18,6 +18,7 @@
 #include <linux/ftrace.h>
 
 #include <asm/machdep.h>
+#include <asm/pgalloc.h>
 #include <asm/prom.h>
 #include <asm/sections.h>
 
@@ -75,6 +76,17 @@ void arch_crash_save_vmcoreinfo(void)
 #ifndef CONFIG_NEED_MULTIPLE_NODES
 	VMCOREINFO_SYMBOL(contig_page_data);
 #endif
+#if defined(CONFIG_PPC64) && defined(CONFIG_SPARSEMEM_VMEMMAP)
+	VMCOREINFO_SYMBOL(vmemmap_list);
+	VMCOREINFO_SYMBOL(mmu_vmemmap_psize);
+	VMCOREINFO_SYMBOL(mmu_psize_defs);
+	VMCOREINFO_STRUCT_SIZE(vmemmap_backing);
+	VMCOREINFO_OFFSET(vmemmap_backing, list);
+	VMCOREINFO_OFFSET(vmemmap_backing, phys);
+	VMCOREINFO_OFFSET(vmemmap_backing, virt_addr);
+	VMCOREINFO_STRUCT_SIZE(mmu_psize_def);
+	VMCOREINFO_OFFSET(mmu_psize_def, shift);
+#endif
 }
 
 /*