On Fri, Oct 25, 2024 at 10:32:14PM +0200, Ard Biesheuvel wrote: > On Fri, 25 Oct 2024 at 21:15, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > > > From: Eric Biggers <ebiggers@xxxxxxxxxx> > > > > Make the CRC32 library export some flags that indicate which CRC32 > > functions are actually executing optimized code at runtime. Set these > > correctly from the architectures that implement the CRC32 functions. > > > > This will be used to determine whether the crc32[c]-$arch shash > > algorithms should be registered in the crypto API. btrfs could also > > start using these flags instead of the hack that it currently uses where > > it parses the crypto_shash_driver_name. > > > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > > --- > > arch/arm64/lib/crc32-glue.c | 15 +++++++++++++++ > > arch/riscv/lib/crc32-riscv.c | 15 +++++++++++++++ > > include/linux/crc32.h | 15 +++++++++++++++ > > lib/crc32.c | 5 +++++ > > 4 files changed, 50 insertions(+) > > > ... > > diff --git a/include/linux/crc32.h b/include/linux/crc32.h > > index 58c632533b08..bf26d454b60d 100644 > > --- a/include/linux/crc32.h > > +++ b/include/linux/crc32.h > > @@ -35,10 +35,25 @@ static inline u32 __pure __crc32c_le(u32 crc, const u8 *p, size_t len) > > if (IS_ENABLED(CONFIG_CRC32_ARCH)) > > return crc32c_le_arch(crc, p, len); > > return crc32c_le_base(crc, p, len); > > } > > > > +/* > > + * crc32_optimizations contains flags that indicate which CRC32 library > > + * functions are using architecture-specific optimizations. Unlike > > + * IS_ENABLED(CONFIG_CRC32_ARCH) it takes into account the different CRC32 > > + * variants and also whether any needed CPU features are available at runtime. > > + */ > > +#define CRC32_LE_OPTIMIZATION BIT(0) /* crc32_le() is optimized */ > > +#define CRC32_BE_OPTIMIZATION BIT(1) /* crc32_be() is optimized */ > > +#define CRC32C_OPTIMIZATION BIT(2) /* __crc32c_le() is optimized */ > > +#if IS_ENABLED(CONFIG_CRC32_ARCH) > > +extern u32 crc32_optimizations; > > +#else > > +#define crc32_optimizations 0 > > +#endif > > + > > Wouldn't it be cleaner to add a new library function for this, instead > of using a global variable? The architecture crc32 modules need to be able to write to this. There could be a setter function and a getter function, but just using a variable is simpler. - Eric
