[PATCH v7 4/6] kho: fix kho_in_debugfs_init() to handle non-FDT blobs

[Breno Leitao <leitao@debian.org>]

kho_in_debugfs_init() has two problems when displaying incoming
sub-blobs in debugfs:

1. It uses the hardcoded property name "fdt" instead of
   KHO_FDT_SUB_TREE_PROP_NAME ("preserved-data"), so it never finds
   subtrees stored by the current kho_add_subtree().

2. It 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 both issues by using KHO_FDT_SUB_TREE_PROP_NAME to find subtrees
and reading the "blob-size" property from the FDT (persisted by
kho_add_subtree()) instead of calling fdt_totalsize().

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 kernel/liveupdate/kexec_handover_debugfs.c | 38 ++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c
index 7a100f2bf3947..fc2baa8b104fd 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/kho/abi/kexec_handover.h>
 #include "kexec_handover_internal.h"
 
 static struct dentry *debugfs_root;
@@ -121,23 +122,36 @@ __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;
-
-		fdt_phys = fdt_getprop(fdt, child, "fdt", &len);
-		if (!fdt_phys)
+		const u64 *blob_phys;
+		const u64 *blob_size;
+		void *blob;
+		size_t size;
+
+		blob_phys = fdt_getprop(fdt, child,
+					KHO_FDT_SUB_TREE_PROP_NAME, &len);
+		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_FDT_SUB_TREE_PROP_NAME, len);
 			continue;
 		}
-		sub_fdt = phys_to_virt(*fdt_phys);
+
+		blob_size = fdt_getprop(fdt, child,
+					KHO_FDT_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_FDT_SUB_TREE_SIZE_PROP_NAME);
+			continue;
+		}
+		size = (size_t)*blob_size;
+
+		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, 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;
 		}
 	}

-- 
2.47.3