firmware_loader: Add debug message with checksum for FW file

Enable dynamic-debug logging of firmware filenames and SHA256 checksums
to clearly identify the firmware files that are loaded by the system.

Example output:
[   34.944619] firmware_class:_request_firmware: i915 0000:00:02.0: Loaded FW: i915/kbl_dmc_ver1_04.bin, sha256: 2cde41c3e5ad181423bcc3e98ff9c49f743c88f18646af4d0b3c3a9664b831a1
[   48.155884] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/cnl/dsp_basefw.bin, sha256: 43f6ac1b066e9bd0423d914960fbbdccb391af27d2b1da1085eee3ea8df0f357
[   49.579540] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/rt274-tplg.bin, sha256: 4b3580da96dc3d2c443ba20c6728d8b665fceb3ed57223c3a57582bbad8e2413
[   49.798196] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/hda-8086280c-tplg.bin, sha256: 5653172579b2be1b51fd69f5cf46e2bac8d63f2a1327924311c13b2f1fe6e601
[   49.859627] firmware_class:_request_firmware: snd_soc_avs 0000:00:1f.3: Loaded FW: intel/avs/dmic-tplg.bin, sha256: 00fb7fbdb74683333400d7e46925dae60db448b88638efcca0b30215db9df63f

Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Reviewed-by: Russ Weight <russell.h.weight@intel.com>
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Link: https://lore.kernel.org/r/20230317224729.1025879-1-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/base/firmware_loader/Kconfig

@@ -24,6 +24,18 @@ config FW_LOADER
 	  You also want to be sure to enable this built-in if you are going to
 	  enable built-in firmware (CONFIG_EXTRA_FIRMWARE).
 
+config FW_LOADER_DEBUG
+	bool "Log filenames and checksums for loaded firmware"
+	depends on DYNAMIC_DEBUG
+	depends on FW_LOADER
+	depends on CRYPTO
+	depends on CRYPTO_SHA256
+	default FW_LOADER
+	help
+	  Select this option to use dynamic debug to log firmware filenames and
+	  SHA256 checksums to the kernel log for each firmware file that is
+	  loaded.
+
 if FW_LOADER
 
 config FW_LOADER_PAGED_BUF

drivers/base/firmware_loader/main.c

@@ -791,6 +791,50 @@ static void fw_abort_batch_reqs(struct firmware *fw)
 	mutex_unlock(&fw_lock);
 }
 
+#if defined(CONFIG_FW_LOADER_DEBUG)
+#include <crypto/hash.h>
+#include <crypto/sha2.h>
+
+static void fw_log_firmware_info(const struct firmware *fw, const char *name, struct device *device)
+{
+	struct shash_desc *shash;
+	struct crypto_shash *alg;
+	u8 *sha256buf;
+	char *outbuf;
+
+	alg = crypto_alloc_shash("sha256", 0, 0);
+	if (!alg)
+		return;
+
+	sha256buf = kmalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
+	outbuf = kmalloc(SHA256_BLOCK_SIZE + 1, GFP_KERNEL);
+	shash = kmalloc(sizeof(*shash) + crypto_shash_descsize(alg), GFP_KERNEL);
+	if (!sha256buf || !outbuf || !shash)
+		goto out_free;
+
+	shash->tfm = alg;
+
+	if (crypto_shash_digest(shash, fw->data, fw->size, sha256buf) < 0)
+		goto out_shash;
+
+	for (int i = 0; i < SHA256_DIGEST_SIZE; i++)
+		sprintf(&outbuf[i * 2], "%02x", sha256buf[i]);
+	outbuf[SHA256_BLOCK_SIZE] = 0;
+	dev_dbg(device, "Loaded FW: %s, sha256: %s\n", name, outbuf);
+
+out_shash:
+	crypto_free_shash(alg);
+out_free:
+	kfree(shash);
+	kfree(outbuf);
+	kfree(sha256buf);
+}
+#else
+static void fw_log_firmware_info(const struct firmware *fw, const char *name,
+				 struct device *device)
+{}
+#endif
+
 /* called from request_firmware() and request_firmware_work_func() */
 static int
 _request_firmware(const struct firmware **firmware_p, const char *name,
@@ -861,11 +905,13 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
 	revert_creds(old_cred);
 	put_cred(kern_cred);
 
- out:
+out:
 	if (ret < 0) {
 		fw_abort_batch_reqs(fw);
 		release_firmware(fw);
 		fw = NULL;
+	} else {
+		fw_log_firmware_info(fw, name, device);
 	}
 
 	*firmware_p = fw;