lib/crypto: poly1305: Consolidate into single module

Consolidate the Poly1305 code into a single module, similar to various
other algorithms (SHA-1, SHA-256, SHA-512, etc.):

- Each arch now provides a header file lib/crypto/$(SRCARCH)/poly1305.h,
  replacing lib/crypto/$(SRCARCH)/poly1305*.c.  The header defines
  poly1305_block_init(), poly1305_blocks(), poly1305_emit(), and
  optionally poly1305_mod_init_arch().  It is included by
  lib/crypto/poly1305.c, and thus the code gets built into the single
  libpoly1305 module, with improved inlining in some cases.

- Whether arch-optimized Poly1305 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.  (The PPC64 one
  remains unconditionally disabled due to 'depends on BROKEN'.)

- Any additional arch-specific translation units for the optimized
  Poly1305 code, such as assembly files, are now compiled by
  lib/crypto/Makefile instead of lib/crypto/$(SRCARCH)/Makefile.

A special consideration is needed because the Adiantum code uses the
poly1305_core_*() functions directly.  For now, just carry forward that
approach.  This means retaining the CRYPTO_LIB_POLY1305_GENERIC kconfig
symbol, and keeping the poly1305_core_*() functions in separate
translation units.  So it's not quite as streamlined I've done with the
other hash functions, but we still get a single libpoly1305 module.

Note: to see the diff from the arm, arm64, and x86 .c files to the new
.h files, view this commit with 'git show -M10'.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250829152513.92459-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 27 insertions, 23 deletions

diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig
index 79b848448e07..9991118c41a9 100644
--- a/lib/crypto/Kconfig
+++ b/lib/crypto/Kconfig
@@ -114,6 +114,33 @@ config CRYPTO_LIB_MD5_ARCH
 	default y if PPC
 	default y if SPARC64
 
+config CRYPTO_LIB_POLY1305
+	tristate
+	help
+	  The Poly1305 library functions.  Select this if your module uses any
+	  of the functions from <crypto/poly1305.h>.
+
+config CRYPTO_LIB_POLY1305_ARCH
+	bool
+	depends on CRYPTO_LIB_POLY1305 && !UML
+	default y if ARM
+	default y if ARM64 && KERNEL_MODE_NEON
+	default y if MIPS
+	# The PPC64 code needs to be fixed to work in softirq context.
+	default y if PPC64 && CPU_LITTLE_ENDIAN && VSX && BROKEN
+	default y if X86_64
+
+# This symbol controls the inclusion of the Poly1305 generic code.  This differs
+# from most of the other algorithms, which handle the generic code
+# "automatically" via __maybe_unused.  This is needed so that the Adiantum code,
+# which calls the poly1305_core_*() functions directly, can enable them.
+config CRYPTO_LIB_POLY1305_GENERIC
+	bool
+	depends on CRYPTO_LIB_POLY1305
+	# Enable if there's no arch impl or the arch impl requires the generic
+	# impl as a fallback.  (Or if selected explicitly.)
+	default y if !CRYPTO_LIB_POLY1305_ARCH || PPC64
+
 config CRYPTO_LIB_POLY1305_RSIZE
 	int
 	default 2 if MIPS
@@ -121,29 +148,6 @@ config CRYPTO_LIB_POLY1305_RSIZE
 	default 9 if ARM || ARM64
 	default 1
 
-config CRYPTO_ARCH_HAVE_LIB_POLY1305
-	bool
-	help
-	  Declares whether the architecture provides an arch-specific
-	  accelerated implementation of the Poly1305 library interface,
-	  either builtin or as a module.
-
-config CRYPTO_LIB_POLY1305_GENERIC
-	tristate
-	default CRYPTO_LIB_POLY1305 if !CRYPTO_ARCH_HAVE_LIB_POLY1305
-	help
-	  This symbol can be selected by arch implementations of the Poly1305
-	  library interface that require the generic code as a fallback, e.g.,
-	  for SIMD implementations. If no arch specific implementation is
-	  enabled, this implementation serves the users of CRYPTO_LIB_POLY1305.
-
-config CRYPTO_LIB_POLY1305
-	tristate
-	help
-	  Enable the Poly1305 library interface. This interface may be fulfilled
-	  by either the generic implementation or an arch-specific one, if one
-	  is available and enabled.
-
 config CRYPTO_LIB_CHACHA20POLY1305
 	tristate
 	select CRYPTO_LIB_CHACHA