kho: fix kho_in_debugfs_init() to handle non-FDT blobs

kho_in_debugfs_init() calls fdt_totalsize() to determine blob sizes, which
assumes all blobs are FDTs.  This breaks for non-FDT blobs like struct
kho_kexec_metadata.

Fix this by reading the "blob-size" property from the FDT (persisted by
kho_add_subtree()) instead of calling fdt_totalsize().  Also rename local
variables from fdt_phys/sub_fdt to blob_phys/blob for consistency with the
non-FDT-specific naming.

Link: https://lore.kernel.org/20260316-kho-v9-4-ed6dcd951988@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 21 insertions, 11 deletions

diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c
index b416846810d7..257ee8a52be6 100644
--- a/kernel/liveupdate/kexec_handover_debugfs.c
+++ b/kernel/liveupdate/kexec_handover_debugfs.c
@@ -122,24 +122,34 @@ __init void kho_in_debugfs_init(struct kho_debugfs *dbg, const void *fdt)
 	fdt_for_each_subnode(child, fdt, 0) {
 		int len = 0;
 		const char *name = fdt_get_name(fdt, child, NULL);
-		const u64 *fdt_phys;
-		void *sub_fdt;
+		const u64 *blob_phys;
+		const u64 *blob_size;
+		void *blob;
 
-		fdt_phys = fdt_getprop(fdt, child,
+		blob_phys = fdt_getprop(fdt, child,
 					KHO_SUB_TREE_PROP_NAME, &len);
-		if (!fdt_phys)
+		if (!blob_phys)
 			continue;
-		if (len != sizeof(*fdt_phys)) {
-			pr_warn("node %s prop fdt has invalid length: %d\n",
-				name, len);
+		if (len != sizeof(*blob_phys)) {
+			pr_warn("node %s prop %s has invalid length: %d\n",
+				name, KHO_SUB_TREE_PROP_NAME, len);
 			continue;
 		}
-		sub_fdt = phys_to_virt(*fdt_phys);
+
+		blob_size = fdt_getprop(fdt, child,
+					KHO_SUB_TREE_SIZE_PROP_NAME, &len);
+		if (!blob_size || len != sizeof(*blob_size)) {
+			pr_warn("node %s missing or invalid %s property\n",
+				name, KHO_SUB_TREE_SIZE_PROP_NAME);
+			continue;
+		}
+
+		blob = phys_to_virt(*blob_phys);
 		err = __kho_debugfs_blob_add(&dbg->fdt_list, sub_fdt_dir, name,
-					     sub_fdt, fdt_totalsize(sub_fdt));
+					     blob, *blob_size);
 		if (err) {
-			pr_warn("failed to add fdt %s to debugfs: %pe\n", name,
-				ERR_PTR(err));
+			pr_warn("failed to add blob %s to debugfs: %pe\n",
+				name, ERR_PTR(err));
 			continue;
 		}
 	}