kho: simplify serialization and remove __kho_abort

Currently, __kho_finalize() performs memory serialization in the middle of
FDT construction.  If FDT construction fails later, the function must
manually clean up the serialized memory via __kho_abort().

Refactor __kho_finalize() to perform kho_mem_serialize() only after the
FDT has been successfully constructed and finished.  This reordering has
two benefits:
1. It avoids expensive serialization work if FDT generation fails.
2. It removes the need for cleanup in the FDT error path.

As a result, the internal helper __kho_abort() is no longer needed for
internal error handling.  Inline its remaining logic (cleanup of the
preserved memory map) directly into kho_abort() and remove the helper.

Link: https://lkml.kernel.org/r/20251114190002.3311679-8-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 17 insertions, 24 deletions

diff --git a/kernel/liveupdate/kexec_handover.c b/kernel/liveupdate/kexec_handover.c
index 3e32c61a64b1..297136054f75 100644
--- a/kernel/liveupdate/kexec_handover.c
+++ b/kernel/liveupdate/kexec_handover.c
@@ -1214,14 +1214,6 @@ void kho_restore_free(void *mem)
 }
 EXPORT_SYMBOL_GPL(kho_restore_free);
 
-static void __kho_abort(void)
-{
-	if (kho_out.preserved_mem_map) {
-		kho_mem_ser_free(kho_out.preserved_mem_map);
-		kho_out.preserved_mem_map = NULL;
-	}
-}
-
 int kho_abort(void)
 {
 	if (!kho_enable)
@@ -1231,7 +1223,8 @@ int kho_abort(void)
 	if (!kho_out.finalized)
 		return -ENOENT;
 
-	__kho_abort();
+	kho_mem_ser_free(kho_out.preserved_mem_map);
+	kho_out.preserved_mem_map = NULL;
 	kho_out.finalized = false;
 
 	return 0;
@@ -1239,12 +1232,12 @@ int kho_abort(void)
 
 static int __kho_finalize(void)
 {
-	int err = 0;
-	u64 *preserved_mem_map;
 	void *root = kho_out.fdt;
 	struct kho_sub_fdt *fdt;
+	u64 *preserved_mem_map;
+	int err;
 
-	err |= fdt_create(root, PAGE_SIZE);
+	err = fdt_create(root, PAGE_SIZE);
 	err |= fdt_finish_reservemap(root);
 	err |= fdt_begin_node(root, "");
 	err |= fdt_property_string(root, "compatible", KHO_FDT_COMPATIBLE);
@@ -1257,13 +1250,7 @@ static int __kho_finalize(void)
 					sizeof(*preserved_mem_map),
 					(void **)&preserved_mem_map);
 	if (err)
-		goto abort;
-
-	err = kho_mem_serialize(&kho_out);
-	if (err)
-		goto abort;
-
-	*preserved_mem_map = (u64)virt_to_phys(kho_out.preserved_mem_map);
+		goto err_exit;
 
 	mutex_lock(&kho_out.fdts_lock);
 	list_for_each_entry(fdt, &kho_out.sub_fdts, l) {
@@ -1277,13 +1264,19 @@ static int __kho_finalize(void)
 
 	err |= fdt_end_node(root);
 	err |= fdt_finish(root);
+	if (err)
+		goto err_exit;
 
-abort:
-	if (err) {
-		pr_err("Failed to convert KHO state tree: %d\n", err);
-		__kho_abort();
-	}
+	err = kho_mem_serialize(&kho_out);
+	if (err)
+		goto err_exit;
+
+	*preserved_mem_map = (u64)virt_to_phys(kho_out.preserved_mem_map);
+
+	return 0;
 
+err_exit:
+	pr_err("Failed to convert KHO state tree: %d\n", err);
 	return err;
 }