x86/boot/compressed/64: Check return value of kernel_ident_mapping_init()

The function can fail to create an identity mapping, check for that
and bail out if it happens.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-22-joro@8bytes.org

arch/x86/boot/compressed/ident_map_64.c

@@ -91,6 +91,8 @@ static struct x86_mapping_info mapping_info;
  */
 static void add_identity_map(unsigned long start, unsigned long end)
 {
+	int ret;
+
 	/* Align boundary to 2M. */
 	start = round_down(start, PMD_SIZE);
 	end = round_up(end, PMD_SIZE);
@@ -98,8 +100,9 @@ static void add_identity_map(unsigned long start, unsigned long end)
 		return;
 
 	/* Build the mapping. */
-	kernel_ident_mapping_init(&mapping_info, (pgd_t *)top_level_pgt,
-				  start, end);
+	ret = kernel_ident_mapping_init(&mapping_info, (pgd_t *)top_level_pgt, start, end);
+	if (ret)
+		error("Error: kernel_ident_mapping_init() failed\n");
 }
 
 /* Locates and clears a region for a new top level page table. */