[RFC PATCH 3/4] kho: Add support for multiple versions to debugfs

[Logan Odell <loganodell@google.com>]

Update kho_in_debugfs_init to search for versioned subnodes
(depth 2) and expose them as name-version in the input debugfs.
This ensures versioned subtrees are visible to userspace for debugging,
matching the behavior of the output side.

Signed-off-by: Logan Odell <loganodell@google.com>
---
 kernel/liveupdate/kexec_handover_debugfs.c | 57 +++++++++++++++++-----
 1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c
index 2f93939168ab..2ca055219900 100644
--- a/kernel/liveupdate/kexec_handover_debugfs.c
+++ b/kernel/liveupdate/kexec_handover_debugfs.c
@@ -13,6 +13,7 @@
 #include <linux/io.h>
 #include <linux/libfdt.h>
 #include <linux/mm.h>
+#include <linux/unaligned.h>
 #include "kexec_handover_internal.h"
 
 static struct dentry *debugfs_root;
@@ -140,19 +141,49 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt)
 		const u64 *fdt_phys;
 
 		fdt_phys = fdt_getprop(fdt, child, "fdt", &len);
-		if (!fdt_phys)
-			continue;
-		if (len != sizeof(*fdt_phys)) {
-			pr_warn("node %s prop fdt has invalid length: %d\n",
-				name, len);
-			continue;
-		}
-		err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir, name,
-					    phys_to_virt(*fdt_phys));
-		if (err) {
-			pr_warn("failed to add fdt %s to debugfs: %pe\n", name,
-				ERR_PTR(err));
-			continue;
+		if (fdt_phys) {
+			if (len != sizeof(*fdt_phys)) {
+				pr_warn("node %s prop fdt has invalid length: %d\n",
+					name, len);
+				continue;
+			}
+			err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir, name,
+						    phys_to_virt(get_unaligned(fdt_phys)));
+			if (err) {
+				pr_warn("failed to add fdt %s to debugfs: %pe\n", name,
+					ERR_PTR(err));
+			}
+		} else {
+			int grandchild;
+
+			fdt_for_each_subnode(grandchild, fdt, child) {
+				const char *gc_name = fdt_get_name(fdt, grandchild, NULL);
+				const u64 *gc_fdt_phys;
+				char *combined_name;
+
+				gc_fdt_phys = fdt_getprop(fdt, grandchild, "fdt", &len);
+				if (!gc_fdt_phys)
+					continue;
+
+				if (len != sizeof(*gc_fdt_phys)) {
+					pr_warn("node %s/%s prop fdt has invalid length: %d\n",
+						name, gc_name, len);
+					continue;
+				}
+
+				combined_name = kasprintf(GFP_KERNEL, "%s-%s", name, gc_name);
+				if (!combined_name)
+					continue;
+
+				err = __kho_debugfs_fdt_add(&dbg->fdt_list, sub_fdt_dir,
+							combined_name,
+							phys_to_virt(get_unaligned(gc_fdt_phys)));
+				kfree(combined_name);
+				if (err) {
+					pr_warn("failed to add fdt %s-%s to debugfs: %pe\n",
+						name, gc_name, ERR_PTR(err));
+				}
+			}
 		}
 	}
 
-- 
2.55.0.508.g3f0d502094-goog