fit: Refactor config node handling

This patch makes some minor refactoring to the way the FIT parser
handles config nodes. A lot of this code was written in the dawn age of
depthcharge when its device tree library wasn't as well-stocked yet, so
some of it can be rewritten nicer with more high-level primitives.
There's no point in storing both the string name and the actual FDT node
of a FIT image node separately, since the latter also contains the
former, so remove that. Also eliminate code for the case of not having
an FDT (which makes no sense), and move some more FDT validity/compat
checking into fit_update_compat() (mostly in anticipation of later
changes).

This patch was adapted from depthcharge's http://crosreview.com/1553456
with a couple of modifications specific to coreboot's custom FIT loading
code.

Change-Id: Ia79e0fd0e1159c4aca64c453b82a0379b133350d
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32870
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 89 insertions, 113 deletions

diff --git a/src/arch/arm64/fit_payload.c b/src/arch/arm64/fit_payload.c
index c4bbceee4c..fd1bae171a 100644
--- a/src/arch/arm64/fit_payload.c
+++ b/src/arch/arm64/fit_payload.c
@@ -184,20 +184,14 @@ bool fit_payload_arch(struct prog *payload, struct fit_config_node *config,
 	bool place_anywhere;
 	void *arg = NULL;
 
-	if (!config->fdt || !fdt) {
-		printk(BIOS_CRIT, "CRIT: Providing a valid FDT is mandatory to "
-		       "boot an ARM64 kernel!\n");
-		return false;
-	}
-
-	if (!decompress_kernel_header(config->kernel_node)) {
+	if (!decompress_kernel_header(config->kernel)) {
 		printk(BIOS_CRIT, "CRIT: Payload doesn't look like an ARM64"
 		       " kernel Image.\n");
 		return false;
 	}
 
 	/* Update kernel size from image header, if possible */
-	kernel->size = get_kernel_size(config->kernel_node);
+	kernel->size = get_kernel_size(config->kernel);
 	printk(BIOS_DEBUG, "FIT: Using kernel size of 0x%zx bytes\n",
 	       kernel->size);
 
diff --git a/src/include/fit.h b/src/include/fit.h
index 6e0667f6cf..758ee70c9c 100644
--- a/src/include/fit.h
+++ b/src/include/fit.h
@@ -27,7 +27,7 @@
 struct fit_image_node
 {
 	const char *name;
-	const void *data;
+	void *data;
 	uint32_t size;
 	int compression;
 
@@ -37,12 +37,9 @@ struct fit_image_node
 struct fit_config_node
 {
 	const char *name;
-	const char *kernel;
-	struct fit_image_node *kernel_node;
-	const char *fdt;
-	struct fit_image_node *fdt_node;
-	const char *ramdisk;
-	struct fit_image_node *ramdisk_node;
+	struct fit_image_node *kernel;
+	struct fit_image_node *fdt;
+	struct fit_image_node *ramdisk;
 	struct fdt_property compat;
 	int compat_rank;
 	int compat_pos;
diff --git a/src/lib/fit.c b/src/lib/fit.c
index c98ba2f802..5fbcd77407 100644
--- a/src/lib/fit.c
+++ b/src/lib/fit.c
@@ -85,6 +85,17 @@ static void fit_add_default_compat_strings(void)
 	fit_add_compat_string(compat_string);
 }
 
+static struct fit_image_node *find_image(const char *name)
+{
+	struct fit_image_node *image;
+	list_for_each(image, image_nodes, list_node) {
+		if (!strcmp(image->name, name))
+			return image;
+	}
+	printk(BIOS_ERR, "ERROR: Cannot find image node %s!\n", name);
+	return NULL;
+}
+
 static void image_node(struct device_tree_node *node)
 {
 	struct fit_image_node *image = xzalloc(sizeof(*image));
@@ -120,11 +131,11 @@ static void config_node(struct device_tree_node *node)
 	struct device_tree_property *prop;
 	list_for_each(prop, node->properties, list_node) {
 		if (!strcmp("kernel", prop->prop.name))
-			config->kernel = prop->prop.data;
+			config->kernel = find_image(prop->prop.data);
 		else if (!strcmp("fdt", prop->prop.name))
-			config->fdt = prop->prop.data;
+			config->fdt = find_image(prop->prop.data);
 		else if (!strcmp("ramdisk", prop->prop.name))
-			config->ramdisk = prop->prop.data;
+			config->ramdisk = find_image(prop->prop.data);
 	}
 
 	list_insert_after(&config->list_node, &config_nodes);
@@ -132,40 +143,22 @@ static void config_node(struct device_tree_node *node)
 
 static void fit_unpack(struct device_tree *tree, const char **default_config)
 {
-	assert(tree && tree->root);
-
-	struct device_tree_node *top;
-	list_for_each(top, tree->root->children, list_node) {
-		struct device_tree_node *child;
-		if (!strcmp("images", top->name)) {
-
-			list_for_each(child, top->children, list_node)
-				image_node(child);
-
-		} else if (!strcmp("configurations", top->name)) {
-			struct device_tree_property *prop;
-			list_for_each(prop, top->properties, list_node) {
-				if (!strcmp("default", prop->prop.name) &&
-						default_config)
-					*default_config = prop->prop.data;
-			}
-
-			list_for_each(child, top->children, list_node)
-				config_node(child);
-		}
+	struct device_tree_node *child;
+	struct device_tree_node *images = dt_find_node_by_path(tree, "/images",
+							       NULL, NULL, 0);
+	if (images)
+		list_for_each(child, images->children, list_node)
+			image_node(child);
+
+	struct device_tree_node *configs = dt_find_node_by_path(tree,
+		"/configurations", NULL, NULL, 0);
+	if (configs) {
+		*default_config = dt_find_string_prop(configs, "default");
+		list_for_each(child, configs->children, list_node)
+			config_node(child);
 	}
 }
 
-static struct fit_image_node *find_image(const char *name)
-{
-	struct fit_image_node *image;
-	list_for_each(image, image_nodes, list_node) {
-		if (!strcmp(image->name, name))
-			return image;
-	}
-	return NULL;
-}
-
 static int fdt_find_compat(const void *blob, uint32_t start_offset,
 			   struct fdt_property *prop)
 {
@@ -393,18 +386,27 @@ void fit_update_memory(struct device_tree *tree)
 
 /*
  * Finds a compat string and updates the compat position and rank.
- * @param fdt_blob Pointer to FDT
  * @param config The current config node to operate on
+ * @return 0 if compat updated, -1 if this FDT cannot be used.
  */
-static void fit_update_compat(const void *fdt_blob,
-			      struct fit_config_node *config)
+static int fit_update_compat(struct fit_config_node *config)
 {
+	if (config->fdt->compression != CBFS_COMPRESS_NONE) {
+		printk(BIOS_ERR,
+		       "FDT compression not yet supported, skipping %s.\n",
+		       config->name);
+		return -1;
+	}
+
+	void *fdt_blob = config->fdt->data;
 	struct compat_string_entry *compat_node;
 	const struct fdt_header *fdt_header =
 		(const struct fdt_header *)fdt_blob;
 	uint32_t fdt_offset = be32_to_cpu(fdt_header->structure_offset);
 	size_t i = 0;
 
+	config->compat_pos = -1;
+	config->compat_rank = -1;
 	if (!fdt_find_compat(fdt_blob, fdt_offset, &config->compat)) {
 		list_for_each(compat_node, compat_strings, list_node) {
 			int pos = fit_check_compat(&config->compat,
@@ -419,6 +421,8 @@ static void fit_update_compat(const void *fdt_blob,
 			i++;
 		}
 	}
+
+	return 0;
 }
 
 struct fit_config_node *fit_load(void *fit)
@@ -457,55 +461,41 @@ struct fit_config_node *fit_load(void *fit)
 	printk(BIOS_DEBUG, "\n");
 	/* Process and list the configs. */
 	list_for_each(config, config_nodes, list_node) {
-		if (config->kernel)
-			config->kernel_node = find_image(config->kernel);
-		if (config->fdt)
-			config->fdt_node = find_image(config->fdt);
-		if (config->ramdisk)
-			config->ramdisk_node = find_image(config->ramdisk);
+		if (!config->kernel) {
+			printk(BIOS_ERR,
+			       "ERROR: config %s has no kernel, skipping.\n",
+			       config->name);
+			continue;
+		}
+		if (!config->fdt) {
+			printk(BIOS_ERR,
+			       "ERROR: config %s has no FDT, skipping.\n",
+			       config->name);
+			continue;
+		}
 
-		if (config->ramdisk_node &&
-		    config->ramdisk_node->compression < 0) {
+		if (config->ramdisk &&
+		    config->ramdisk->compression < 0) {
 			printk(BIOS_WARNING, "WARN: Ramdisk is compressed with "
 			       "an unsupported algorithm, discarding config %s."
 			       "\n", config->name);
-			list_remove(&config->list_node);
 			continue;
 		}
 
-		if (!config->kernel_node ||
-		    (config->fdt && !config->fdt_node)) {
-			printk(BIOS_DEBUG, "FIT: Missing image, discarding "
-			       "config %s.\n", config->name);
-			list_remove(&config->list_node);
+		if (fit_update_compat(config))
 			continue;
-		}
 
-		if (config->fdt_node) {
-			if (config->fdt_node->compression !=
-			    CBFS_COMPRESS_NONE) {
-				printk(BIOS_DEBUG,
-				       "FIT: FDT compression not yet supported,"
-				       " skipping config %s.\n", config->name);
-				list_remove(&config->list_node);
-				continue;
-			}
-
-			config->compat_pos = -1;
-			config->compat_rank = -1;
-
-			fit_update_compat(config->fdt_node->data, config);
-		}
 		printk(BIOS_DEBUG, "FIT: config %s", config->name);
 		if (default_config_name &&
 		    !strcmp(config->name, default_config_name)) {
 			printk(BIOS_DEBUG, " (default)");
 			default_config = config;
 		}
-		if (config->fdt)
-			printk(BIOS_DEBUG, ", fdt %s", config->fdt);
+		printk(BIOS_DEBUG, ", kernel %s", config->kernel->name);
+		printk(BIOS_DEBUG, ", fdt %s", config->fdt->name);
 		if (config->ramdisk)
-			printk(BIOS_DEBUG, ", ramdisk %s", config->ramdisk);
+			printk(BIOS_DEBUG, ", ramdisk %s",
+			       config->ramdisk->name);
 		if (config->compat.name) {
 			printk(BIOS_DEBUG, ", compat");
 			int bytes = config->compat.size;
diff --git a/src/lib/fit_payload.c b/src/lib/fit_payload.c
index e0158f2129..4bc6622b19 100644
--- a/src/lib/fit_payload.c
+++ b/src/lib/fit_payload.c
@@ -176,37 +176,34 @@ void fit_payload(struct prog *payload)
 
 	struct fit_config_node *config = fit_load(data);
 
-	if (!config || !config->kernel_node) {
+	if (!config) {
 		printk(BIOS_ERR, "ERROR: Could not load FIT\n");
 		rdev_munmap(prog_rdev(payload), data);
 		return;
 	}
 
-	if (config->fdt_node) {
-		dt = fdt_unflatten(config->fdt_node->data);
-		if (!dt) {
-			printk(BIOS_ERR,
-			       "ERROR: Failed to unflatten the FDT.\n");
-			rdev_munmap(prog_rdev(payload), data);
-			return;
-		}
+	dt = fdt_unflatten(config->fdt->data);
+	if (!dt) {
+		printk(BIOS_ERR, "ERROR: Failed to unflatten the FDT.\n");
+		rdev_munmap(prog_rdev(payload), data);
+		return;
+	}
 
-		dt_apply_fixups(dt);
+	dt_apply_fixups(dt);
 
-		/* Insert coreboot specific information */
-		add_cb_fdt_data(dt);
+	/* Insert coreboot specific information */
+	add_cb_fdt_data(dt);
 
-		/* Update device_tree */
+	/* Update device_tree */
 #if defined(CONFIG_LINUX_COMMAND_LINE)
-		fit_update_chosen(dt, (char *)CONFIG_LINUX_COMMAND_LINE);
+	fit_update_chosen(dt, (char *)CONFIG_LINUX_COMMAND_LINE);
 #endif
-		fit_update_memory(dt);
-	}
+	fit_update_memory(dt);
 
 	/* Collect infos for fit_payload_arch */
-	kernel.size = config->kernel_node->size;
+	kernel.size = config->kernel->size;
 	fdt.size = dt ? dt_flat_size(dt) : 0;
-	initrd.size = config->ramdisk_node ? config->ramdisk_node->size : 0;
+	initrd.size = config->ramdisk ? config->ramdisk->size : 0;
 
 	/* Invoke arch specific payload placement and fixups */
 	if (!fit_payload_arch(payload, config, &kernel, &fdt, &initrd)) {
@@ -216,17 +213,15 @@ void fit_payload(struct prog *payload)
 		return;
 	}
 
-	/* Load the images to given position */
-	if (config->fdt_node) {
-		/* Update device_tree */
-		if (config->ramdisk_node)
-			fit_add_ramdisk(dt, (void *)initrd.offset, initrd.size);
+	/* Update ramdisk location in FDT */
+	if (config->ramdisk)
+		fit_add_ramdisk(dt, (void *)initrd.offset, initrd.size);
 
-		pack_fdt(&fdt, dt);
-	}
+	/* Repack FDT for handoff to kernel */
+	pack_fdt(&fdt, dt);
 
-	if (config->ramdisk_node &&
-	    extract(&initrd, config->ramdisk_node)) {
+	if (config->ramdisk &&
+	    extract(&initrd, config->ramdisk)) {
 		printk(BIOS_ERR, "ERROR: Failed to extract initrd\n");
 		prog_set_entry(payload, NULL, NULL);
 		rdev_munmap(prog_rdev(payload), data);
@@ -235,7 +230,7 @@ void fit_payload(struct prog *payload)
 
 	timestamp_add_now(TS_KERNEL_DECOMPRESSION);
 
-	if (extract(&kernel, config->kernel_node)) {
+	if (extract(&kernel, config->kernel)) {
 		printk(BIOS_ERR, "ERROR: Failed to extract kernel\n");
 		prog_set_entry(payload, NULL, NULL);
 		rdev_munmap(prog_rdev(payload), data);