Re: [PATCH v8 4/6] kho: fix kho_in_debugfs_init() to handle non-FDT blobs

Mike Rapoport
2026-03-10T10:36:51Z

On Mon, Mar 09, 2026 at 06:41:47AM -0700, Breno Leitao wrote:
> 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_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_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>

Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

> ---
> kernel/liveupdate/kexec_handover_debugfs.c | 34 ++++++++++++++++++++----------
> 1 file changed, 23 insertions(+), 11 deletions(-)
>
> diff --git a/kernel/liveupdate/kexec_handover_debugfs.c b/kernel/liveupdate/kexec_handover_debugfs.c
> index 7a100f2bf3947..257ee8a52be66 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 +122,34 @@ __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, "fdt", &len);
> - if (!fdt_phys)
> + blob_phys = fdt_getprop(fdt, child,
> + KHO_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_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;
> }
> }
>
> --
> 2.47.3
>

--
Sincerely yours,
Mike.