cbfs: Port cbfs_load() and cbfs_map() to new API

This patch adapts cbfs_load() and cbfs_map() to use the new CBFS API
directly, rather than through cbfs_boot_locate(). For cbfs_load() this
means that attribute metadata does not need to be read twice.

Change-Id: I754cc34b1c1471129e15475aa0f1891e02439a02
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39305
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

2 files changed, 37 insertions, 0 deletions

diff --git a/src/commonlib/bsd/cbfs_private.c b/src/commonlib/bsd/cbfs_private.c
index 035684b91e6f..7814c4a7271b 100644
--- a/src/commonlib/bsd/cbfs_private.c
+++ b/src/commonlib/bsd/cbfs_private.c
@@ -159,3 +159,35 @@ cb_err_t cbfs_lookup(cbfs_dev_t dev, const char *name, union cbfs_mdata *mdata_o
 	};
 	return cbfs_walk(dev, lookup_walker, &args, metadata_hash, 0);
 }
+
+const void *cbfs_find_attr(const union cbfs_mdata *mdata, uint32_t attr_tag, size_t size_check)
+{
+	uint32_t offset = be32toh(mdata->h.attributes_offset);
+	uint32_t end = be32toh(mdata->h.offset);
+
+	if (!offset)
+		return NULL;
+
+	while (offset + sizeof(struct cbfs_file_attribute) <= end) {
+		const struct cbfs_file_attribute *attr = (const void *)mdata->raw + offset;
+		const uint32_t tag = be32toh(attr->tag);
+		const uint32_t len = be32toh(attr->len);
+
+		if (offset + len > end) {
+			ERROR("Attribute %s[%u] overflows end of metadata\n",
+			      mdata->filename, tag);
+			return NULL;
+		}
+		if (tag == attr_tag) {
+			if (size_check && len != size_check) {
+				ERROR("Attribute %s[%u] size mismatch: %u != %zu\n",
+				      mdata->filename, tag, len, size_check);
+				return NULL;
+			}
+			return attr;
+		}
+		offset += len;
+	}
+
+	return NULL;
+}
diff --git a/src/commonlib/bsd/include/commonlib/bsd/cbfs_private.h b/src/commonlib/bsd/include/commonlib/bsd/cbfs_private.h
index 64dcf9f5bac8..b72463aba3df 100644
--- a/src/commonlib/bsd/include/commonlib/bsd/cbfs_private.h
+++ b/src/commonlib/bsd/include/commonlib/bsd/cbfs_private.h
@@ -134,4 +134,9 @@ cb_err_t cbfs_mcache_lookup(const void *mcache, size_t mcache_size, const char *
 /* Returns the amount of bytes actually used by the CBFS metadata cache in |mcache|. */
 size_t cbfs_mcache_real_size(const void *mcache, size_t mcache_size);
 
+/* Finds a CBFS attribute in a metadata block. Attribute returned as-is (still big-endian).
+   If |size| is not 0, will check that it matches the length of the attribute (if found)...
+   else caller is responsible for checking the |len| field to avoid reading out-of-bounds. */
+const void *cbfs_find_attr(const union cbfs_mdata *mdata, uint32_t attr_tag, size_t size_check);
+
 #endif	/* _COMMONLIB_BSD_CBFS_PRIVATE_H_ */