| Message ID | 20250405182609.404216-1-ebiggers@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Remove per-architecture ChaCha skcipher glue code | expand |
Eric Biggers <ebiggers@kernel.org> wrote: > Currently each architecture exposes ChaCha not only through the library > API, but also through the crypto_skcipher API. That requires each > architecture to implement essentially the same skcipher glue code. > > Following the example of what's been done for crc32 and crc32c, > eliminate this redundancy by making crypto/chacha.c register both the > generic and architecture-optimized skcipher algorithms, implemented on > top of the appropriate library functions. This removes almost 800 lines > of code and disentangles the library code from the skcipher API. > > From what I remember, the following are the reasons why it wasn't just > done this way originally. But none of these really hold water: > > - The skcipher code was there first, so it may have seemed more natural > to add onto it rather than replace it. > > - Architectures could register multiple skcipher algorithms using > different CPU features and have them all be tested in a single boot. > This was convenient in theory, but it never really worked properly. > It didn't apply to the library code, the x86 ChaCha code wasn't > actually doing this (it used static keys instead), and this cannot > catch bugs like accidentally using an AVX instruction in SSE code. > Instead, a correct solution, which also doesn't require any special > kernel support, is to just boot the kernel in QEMU using different > -cpu arguments as needed to test all the code. > > - There was a concern about changing cra_driver_names potentially > breaking users. But in practice users rely on cra_name, not > cra_driver_name. We already change, add, and remove cra_driver_names > occasionally for various reasons. And even if someone was relying on > a specific cra_driver_name, there are some more lightweight > compatibility tricks that could be used. > > - There was a desire for users to be able to override the kernel's > choice of ChaCha implementation by blacklisting the arch-optimized > ChaCha module. But that already became mostly impossible when the > library functions were added to the same module. And in practice > users don't do this anyway. Even if, hypothetically, someone really > needed to do this and for some reason the kernel couldn't be fixed to > make the right choice in their case automatically, there are other > ways this could be implemented such as a module parameter. > > Eric Biggers (9): > crypto: riscv/chacha - implement library instead of skcipher > crypto: chacha - centralize the skcipher wrappers for arch code > crypto: arm/chacha - remove the redundant skcipher algorithms > crypto: arm64/chacha - remove the skcipher algorithms > crypto: mips/chacha - remove the skcipher algorithms > crypto: powerpc/chacha - remove the skcipher algorithms > crypto: s390/chacha - remove the skcipher algorithms > crypto: x86/chacha - remove the skcipher algorithms > crypto: chacha - remove <crypto/internal/chacha.h> > > arch/arm/crypto/Kconfig | 7 - > arch/arm/crypto/chacha-glue.c | 243 +--------------------- > arch/arm/crypto/chacha-neon-core.S | 2 +- > arch/arm64/crypto/Kconfig | 7 - > arch/arm64/crypto/chacha-neon-core.S | 2 +- > arch/arm64/crypto/chacha-neon-glue.c | 146 +------------ > arch/mips/crypto/Kconfig | 6 - > arch/mips/crypto/chacha-glue.c | 131 +----------- > arch/powerpc/crypto/Kconfig | 8 - > arch/powerpc/crypto/chacha-p10-glue.c | 147 +------------- > arch/riscv/crypto/Kconfig | 11 +- > arch/riscv/crypto/chacha-riscv64-glue.c | 112 ++++------ > arch/riscv/crypto/chacha-riscv64-zvkb.S | 71 +++---- > arch/s390/crypto/Kconfig | 7 - > arch/s390/crypto/chacha-glue.c | 99 ++------- > arch/x86/crypto/Kconfig | 9 - > arch/x86/crypto/chacha_glue.c | 144 +------------ > crypto/Makefile | 3 +- > crypto/chacha.c | 260 ++++++++++++++++++++++++ > crypto/chacha_generic.c | 139 ------------- > include/crypto/chacha.h | 9 + > include/crypto/internal/chacha.h | 43 ---- > 22 files changed, 413 insertions(+), 1193 deletions(-) > create mode 100644 crypto/chacha.c > delete mode 100644 crypto/chacha_generic.c > delete mode 100644 include/crypto/internal/chacha.h > > base-commit: 56f944529ec2292cbe63377a76df3759d702dd39 All applied. Thanks.