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>

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;
+}

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_ */

src/lib/cbfs.c

@@ -72,18 +72,16 @@ int cbfs_boot_locate(struct cbfsf *fh, const char *name, uint32_t *type)
 
 void *cbfs_map(const char *name, size_t *size_out)
 {
-	struct cbfsf fh;
-	size_t fsize;
+	struct region_device rdev;
+	union cbfs_mdata mdata;
 
-	if (cbfs_boot_locate(&fh, name, NULL))
+	if (cbfs_boot_lookup(name, false, &mdata, &rdev))
 		return NULL;
 
-	fsize = region_device_sz(&fh.data);
-
 	if (size_out != NULL)
-		*size_out = fsize;
+		*size_out = region_device_sz(&rdev);
 
-	return rdev_mmap(&fh.data, 0, fsize);
+	return rdev_mmap_full(&rdev);
 }
 
 int cbfs_unmap(void *mapping)
@@ -285,21 +283,23 @@ void *cbfs_boot_map_optionrom_revision(uint16_t vendor, uint16_t device, uint8_t
 
 size_t cbfs_load(const char *name, void *buf, size_t buf_size)
 {
-	struct cbfsf fh;
-	uint32_t compression_algo;
-	size_t decompressed_size;
+	struct region_device rdev;
+	union cbfs_mdata mdata;
 
-	if (cbfs_boot_locate(&fh, name, NULL) < 0)
+	if (cbfs_boot_lookup(name, false, &mdata, &rdev))
 		return 0;
 
-	if (cbfsf_decompression_info(&fh, &compression_algo,
-				     &decompressed_size)
-		    < 0
-	    || decompressed_size > buf_size)
-		return 0;
+	uint32_t compression = CBFS_COMPRESS_NONE;
+	const struct cbfs_file_attr_compression *attr = cbfs_find_attr(&mdata,
+				CBFS_FILE_ATTR_TAG_COMPRESSION, sizeof(*attr));
+	if (attr) {
+		compression = be32toh(attr->compression);
+		if (buf_size < be32toh(attr->decompressed_size))
+			return 0;
+	}
 
-	return cbfs_load_and_decompress(&fh.data, 0, region_device_sz(&fh.data),
-					buf, buf_size, compression_algo);
+	return cbfs_load_and_decompress(&rdev, 0, region_device_sz(&rdev),
+					buf, buf_size, compression);
 }
 
 int cbfs_prog_stage_load(struct prog *pstage)