As I did for sha512_blocks(), reorganize x86's sha256_blocks() to be
just a static_call. To achieve that, for each assembly function add a C
function that handles the kernel-mode FPU section and fallback. While
this increases total code size slightly, the amount of code actually
executed on a given system does not increase, and it is slightly more
efficient since it eliminates the extra static_key. It also makes the
assembly functions be called with standard direct calls instead of
static calls, eliminating the need for ANNOTATE_NOENDBR.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250704023958.73274-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Consolidate the CPU-based SHA-256 code into a single module, following
what I did with SHA-512:
- Each arch now provides a header file lib/crypto/$(SRCARCH)/sha256.h,
replacing lib/crypto/$(SRCARCH)/sha256.c. The header defines
sha256_blocks() and optionally sha256_mod_init_arch(). It is included
by lib/crypto/sha256.c, and thus the code gets built into the single
libsha256 module, with proper inlining and dead code elimination.
- sha256_blocks_generic() is moved from lib/crypto/sha256-generic.c into
lib/crypto/sha256.c. It's now a static function marked with
__maybe_unused, so the compiler automatically eliminates it in any
cases where it's not used.
- Whether arch-optimized SHA-256 is buildable is now controlled
centrally by lib/crypto/Kconfig instead of by
lib/crypto/$(SRCARCH)/Kconfig. The conditions for enabling it remain
the same as before, and it remains enabled by default.
- Any additional arch-specific translation units for the optimized
SHA-256 code (such as assembly files) are now compiled by
lib/crypto/Makefile instead of lib/crypto/$(SRCARCH)/Makefile.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-13-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
