[PATCH v2 1/2] PBL: add pbl_sha256()

[Sascha Hauer]

The PBL open-codes SHA-256 as sha256_init()/sha256_update()/sha256_final()
wherever it needs to hash a blob, which always uses the generic C transform.
Add pbl_sha256(), a one-shot helper that hides this behind a single call and
is free to pick the best transform available in the PBL. For now it only
wraps the generic C implementation; an accelerated path is added on top in a
later commit.

Convert pbl_barebox_verify() in pbl/decomp.c to the new helper as the first
user.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 include/crypto/pbl-sha.h |  4 ++++
 pbl/Makefile             |  1 +
 pbl/decomp.c             |  6 +-----
 pbl/sha256.c             | 25 +++++++++++++++++++++++++
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/include/crypto/pbl-sha.h b/include/crypto/pbl-sha.h
index 7d323ab479..2508448ab4 100644
--- a/include/crypto/pbl-sha.h
+++ b/include/crypto/pbl-sha.h
@@ -3,6 +3,7 @@
 
 #define __PBL_SHA_H_
 
+#include <crypto/sha.h>
 #include <digest.h>
 #include <types.h>
 
@@ -10,4 +11,7 @@ int sha256_init(struct digest *desc);
 int sha256_update(struct digest *desc, const void *data, unsigned long len);
 int sha256_final(struct digest *desc, u8 *out);
 
+/* One-shot SHA-256 that picks the best transform available in the PBL. */
+void pbl_sha256(const void *buf, size_t len, u8 out[SHA256_DIGEST_SIZE]);
+
 #endif /* __PBL-SHA_H_ */
diff --git a/pbl/Makefile b/pbl/Makefile
index 45cfbf5fba..4506f192fe 100644
--- a/pbl/Makefile
+++ b/pbl/Makefile
@@ -6,6 +6,7 @@
 pbl-y += misc.o
 pbl-y += string.o
 pbl-y += malloc.o
+pbl-y += sha256.o
 pbl-$(CONFIG_HAVE_IMAGE_COMPRESSION) += decomp.o
 pbl-$(CONFIG_LIBFDT) += fdt.o
 pbl-$(CONFIG_PBL_CONSOLE) += console.o
diff --git a/pbl/decomp.c b/pbl/decomp.c
index 1539a6b67e..2b3c35012f 100644
--- a/pbl/decomp.c
+++ b/pbl/decomp.c
@@ -58,8 +58,6 @@ extern unsigned char sha_sum_end[];
 int pbl_barebox_verify(const void *compressed_start, unsigned int len,
 		       const void *hash, unsigned int hash_len)
 {
-	struct sha256_state sha_state = { 0 };
-	struct digest d = { .ctx = &sha_state };
 	char computed_hash[SHA256_DIGEST_SIZE];
 	int i;
 	const char *char_hash = hash;
@@ -67,9 +65,7 @@ int pbl_barebox_verify(const void *compressed_start, unsigned int len,
 	if (hash_len != SHA256_DIGEST_SIZE)
 		return -1;
 
-	sha256_init(&d);
-	sha256_update(&d, compressed_start, len);
-	sha256_final(&d, computed_hash);
+	pbl_sha256(compressed_start, len, computed_hash);
 	if (IS_ENABLED(CONFIG_DEBUG_LL)) {
 		puts_ll("CH ");
 
diff --git a/pbl/sha256.c b/pbl/sha256.c
new file mode 100644
index 0000000000..853d6bcbf6
--- /dev/null
+++ b/pbl/sha256.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * pbl_sha256() - one-shot SHA-256 for the PBL, picking the best available
+ * implementation.
+ */
+
+#include <common.h>
+#include <crypto/sha.h>
+#include <crypto/pbl-sha.h>
+#include <digest.h>
+
+static void pbl_sha256_generic(const void *buf, size_t len, u8 *out)
+{
+	struct sha256_state state = { };
+	struct digest d = { .ctx = &state, .length = SHA256_DIGEST_SIZE };
+
+	sha256_init(&d);
+	sha256_update(&d, buf, len);
+	sha256_final(&d, out);
+}
+
+void pbl_sha256(const void *buf, size_t len, u8 out[static SHA256_DIGEST_SIZE])
+{
+	pbl_sha256_generic(buf, len, out);
+}

-- 
2.47.3