SECLIB-667: Accelerate SHA-512 with A64 crypto extensions
Provide an additional pair of #defines, MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
and MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY. At most one of them may be
specified. If used, it is necessary to compile with -march=armv8.2-a+sha3.
The MBEDTLS_SHA512_PROCESS_ALT and MBEDTLS_SHA512_ALT mechanisms
continue to work, and are mutually exclusive with SHA512_USE_A64_CRYPTO.
There should be minimal code size impact if no A64_CRYPTO option is set.
The SHA-512 implementation was originally written by Simon Tatham for PuTTY,
under the MIT licence; dual-licensed as Apache 2 with his kind permission.
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
diff --git a/include/mbedtls/check_config.h b/include/mbedtls/check_config.h
index 06ba6b7..45f4cc5 100644
--- a/include/mbedtls/check_config.h
+++ b/include/mbedtls/check_config.h
@@ -605,6 +605,61 @@
#error "MBEDTLS_SHA384_C defined without MBEDTLS_SHA512_C"
#endif
+#if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT) && \
+ defined(MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY)
+#error "Must only define one of MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#endif
+
+#if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT) || \
+ defined(MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY)
+#if !defined(MBEDTLS_SHA512_C)
+#error "MBEDTLS_SHA512_USE_A64_CRYPTO_* defined without MBEDTLS_SHA512_C"
+#endif
+#if defined(MBEDTLS_SHA512_ALT) || defined(MBEDTLS_SHA512_PROCESS_ALT)
+#error "MBEDTLS_SHA512_*ALT can't be used with MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+#endif
+/*
+ * Best performance comes from most recent compilers, with intrinsics and -O3.
+ * Must compile with -march=armv8.2-a+sha3, but we can't detect armv8.2-a, and
+ * can't always detect __ARM_FEATURE_SHA512 (notably clang 7-12).
+ *
+ * GCC < 8 won't work at all (lacks the sha512 instructions)
+ * GCC >= 8 uses intrinsics, sets __ARM_FEATURE_SHA512
+ *
+ * Clang < 7 won't work at all (lacks the sha512 instructions)
+ * Clang 7-12 don't have intrinsics (but we work around that with inline
+ * assembler) or __ARM_FEATURE_SHA512
+ * Clang == 13.0.0 same as clang 12 (only seen on macOS)
+ * Clang >= 13.0.1 has __ARM_FEATURE_SHA512 and intrinsics
+ */
+#if defined(__aarch64__) && !defined(__ARM_FEATURE_SHA512)
+ /* Test Clang first, as it defines __GNUC__ */
+# if defined(__clang__)
+# if __clang_major__ < 7
+# error "A more recent Clang is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+# elif __clang_major__ < 13 || \
+ (__clang_major__ == 13 && __clang_minor__ == 0 && __clang_patchlevel__ == 0)
+ /* We implement the intrinsics with inline assembler, so don't error */
+# else
+# error "Must use minimum -march=armv8.2-a+sha3 for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+# endif
+# elif defined(__GNUC__)
+# if __GNUC__ < 8
+# error "A more recent GCC is required for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+# else
+# error "Must use minimum -march=armv8.2-a+sha3 for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+# endif
+# else
+# error "Only GCC and Clang supported for MBEDTLS_SHA512_USE_A64_CRYPTO_*"
+# endif
+#endif
+
+#endif /* MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT || MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY */
+
+#if defined(MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY) && !defined(__aarch64__)
+#error "MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY defined on non-Aarch64 system"
+#endif
+
#if defined(MBEDTLS_SHA224_C) && !defined(MBEDTLS_SHA256_C)
#error "MBEDTLS_SHA224_C defined without MBEDTLS_SHA256_C"
#endif
diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 1c631b5..fe1b7d4 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -2841,6 +2841,60 @@
#define MBEDTLS_SHA512_C
/**
+ * \def MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
+ *
+ * Enable acceleration of the SHA-512 cryptographic hash algorithm with the
+ * Arm A64 cryptographic extensions if they are available at runtime. If not,
+ * it will fall back to the C implementation.
+ *
+ * \note If MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT is defined when building
+ * for a non-Aarch64 build it will be silently ignored.
+ *
+ * \note The code uses the SHA-512 Neon intrinsics, so requires GCC >= 8 or
+ * Clang >= 7, and \c CFLAGS must be set to a minimum of
+ * \c -march=armv8.2-a+sha3. An optimisation level of \c -O3 generates the
+ * fastest code.
+ *
+ * \warning MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT cannot be defined at the
+ * same time as MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY.
+ *
+ * Requires: MBEDTLS_SHA512_C.
+ *
+ * Module: library/sha512.c
+ *
+ * Uncomment to have the library check for the A64 SHA-512 crypto extensions
+ * and use them if available.
+ */
+//#define MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
+
+/**
+ * \def MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY
+ *
+ * Enable acceleration of the SHA-512 cryptographic hash algorithm with the
+ * Arm A64 cryptographic extensions, which must be available at runtime (or
+ * an illegal instruction fault will occur).
+ *
+ * \note This allows builds with a smaller code size than with
+ * MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT
+ *
+ * \note The code uses the SHA-512 Neon intrinsics, so requires GCC >= 8 or
+ * Clang >= 7, and \c CFLAGS must be set to a minimum of
+ * \c -march=armv8.2-a+sha3. An optimisation level of \c -O3 generates the
+ * fastest code.
+ *
+ * \warning MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY cannot be defined at the same
+ * time as MBEDTLS_SHA512_USE_A64_CRYPTO_IF_PRESENT.
+ *
+ * Requires: MBEDTLS_SHA512_C.
+ *
+ * Module: library/sha512.c
+ *
+ * Uncomment to have the library use the A64 SHA-512 crypto extensions
+ * unconditionally.
+ */
+//#define MBEDTLS_SHA512_USE_A64_CRYPTO_ONLY
+
+/**
* \def MBEDTLS_SSL_CACHE_C
*
* Enable simple SSL cache implementation.