On Mon, 21 Jul 2025 at 14:18, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > On Mon, Jul 21, 2025 at 01:31:47PM +1000, Ard Biesheuvel wrote: > > On Sat, 19 Jul 2025 at 08:07, Eric Biggers <ebiggers@xxxxxxxxxx> wrote: > > > > > > Now that the oldest supported binutils version is 2.30, the macros that > > > emit the SHA-512 instructions as '.inst' words are no longer needed. So > > > drop them. No change in the generated machine code. > > > > > > Changed from the original patch by Ard Biesheuvel: > > > (https://lore.kernel.org/r/20250515142702.2592942-2-ardb+git@xxxxxxxxxx): > > > - Reduced scope to just SHA-512 > > > - Added comment that explains why "sha3" is used instead of "sha2" > > > > > > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx> > > > > Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > > > Nit below > > > > > --- > > > > > > This patch is targeting libcrypto-next > > > > > > lib/crypto/arm64/sha512-ce-core.S | 27 +++++++-------------------- > > > 1 file changed, 7 insertions(+), 20 deletions(-) > > > > > > diff --git a/lib/crypto/arm64/sha512-ce-core.S b/lib/crypto/arm64/sha512-ce-core.S > > > index 7d870a435ea38..eaa485244af52 100644 > > > --- a/lib/crypto/arm64/sha512-ce-core.S > > > +++ b/lib/crypto/arm64/sha512-ce-core.S > > > @@ -10,30 +10,17 @@ > > > */ > > > > > > #include <linux/linkage.h> > > > #include <asm/assembler.h> > > > > > > - .irp b,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19 > > > - .set .Lq\b, \b > > > - .set .Lv\b\().2d, \b > > > - .endr > > > - > > > - .macro sha512h, rd, rn, rm > > > - .inst 0xce608000 | .L\rd | (.L\rn << 5) | (.L\rm << 16) > > > - .endm > > > - > > > - .macro sha512h2, rd, rn, rm > > > - .inst 0xce608400 | .L\rd | (.L\rn << 5) | (.L\rm << 16) > > > - .endm > > > - > > > - .macro sha512su0, rd, rn > > > - .inst 0xcec08000 | .L\rd | (.L\rn << 5) > > > - .endm > > > - > > > - .macro sha512su1, rd, rn, rm > > > - .inst 0xce608800 | .L\rd | (.L\rn << 5) | (.L\rm << 16) > > > - .endm > > > + /* > > > + * While SHA-512 is part of the SHA-2 family of algorithms, the > > > + * corresponding arm64 instructions are actually part of the "sha3" CPU > > > + * feature. (Except in binutils 2.30 through 2.42, which used "sha2". > > > > Nit: the ARM ARM describes these features as FEAT_SHA256, FEAT_SHA512 > > and FEAT_SHA3, and the latter two happen to have appeared in the same > > architecture revision. So this is likely just the GCC/binutils devs > > getting confused, and assuming a) that SHA-3 implies SHA-2 (which is > > silly if you know the difference) and b) SHA512 has anything to do > > with SHA-3. > > How does the following look? > > /* > * We have to specify the "sha3" feature here, since the GNU and clang > * assemblers both consider the SHA-512 instructions to be part of the > * "sha3" feature. (Except binutils 2.30 through 2.42, which used > * "sha2". But "sha3" implies "sha2", so "sha3" still works in those > * versions.) "sha3" doesn't make a lot of sense, since SHA-512 is part > * of the SHA-2 family of algorithms, and also the Arm Architecture > * Reference Manual defines FEAT_SHA512 and FEAT_SHA3 separately. > * Regardless, we must use "sha3" to be compatible with the assemblers. > */ > LGTM > By the way, the ARM ARM does actually have the following: > > If FEAT_SHA256 is implemented, then FEAT_SHA1 is implemented. > If FEAT_SHA512 is implemented, then FEAT_SHA256 and FEAT_SHA1 are implemented. > If FEAT_SHA3 is implemented, then FEAT_SHA256 and FEAT_SHA1 are implemented. > > So some of the SHAs do imply other ones. But notably absent is > FEAT_SHA3 implying FEAT_SHA512... Yeah, and such policies usually evaporate into thin air as soon as Apple decides to implement something different, so they tend to be rather meaningless. (E.g, FEAT_SME used to imply FEAT_SVE but it no longer does)
