tree e2f58ca6a2ef2f01c9c3ddc6d7a6e19e8108a108
parent af561c221d3af70bd0aa48024db4f1fcf1988eef
author David Benjamin <davidben@google.com> 1640629642 -0500
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> 1641412755 +0000

Enable SHA-512 ARM acceleration when available.

This imports the changes to sha512-armv8.pl from
upstream's af0fcf7b4668218b24d9250b95e0b96939ccb4d1.

Tweaks needed:
- Add an explicit .text because we put .LK$BITS in .rodata for XOM
- .LK$bits and code are in separate sections, so use adrp/add instead of
  plain adr
- Where glibc needs feature flags to *enable* pthread_rwlock, Apple
  interprets _XOPEN_SOURCE as a request to *disable* Apple extensions.
  Tighten the condition on the _XOPEN_SOURCE check.

Added support for macOS and Linux, tested manually on an ARM Mac and a
VM, respectively. Fuchsia and Windows do not currently have APIs to
expose this bit, so I've left in TODOs. Benchmarks from an Apple M1 Max:

Before:
Did 4647000 SHA-512 (16 bytes) operations in 1000103us (74.3 MB/sec)
Did 1614000 SHA-512 (256 bytes) operations in 1000379us (413.0 MB/sec)
Did 439000 SHA-512 (1350 bytes) operations in 1001694us (591.6 MB/sec)
Did 76000 SHA-512 (8192 bytes) operations in 1011821us (615.3 MB/sec)
Did 39000 SHA-512 (16384 bytes) operations in 1024311us (623.8 MB/sec)

After:
Did 10369000 SHA-512 (16 bytes) operations in 1000088us (165.9 MB/sec) [+123.1%]
Did 3650000 SHA-512 (256 bytes) operations in 1000079us (934.3 MB/sec) [+126.2%]
Did 1029000 SHA-512 (1350 bytes) operations in 1000521us (1388.4 MB/sec) [+134.7%]
Did 175000 SHA-512 (8192 bytes) operations in 1001874us (1430.9 MB/sec) [+132.5%]
Did 89000 SHA-512 (16384 bytes) operations in 1010314us (1443.3 MB/sec) [+131.4%]

(This doesn't seem to change the overall SHA-256 vs SHA-512 performance
question on ARM, when hashing perf matters. SHA-256 on the same chip
gets up to 2454.6 MB/s.)

In terms of build coverage, for now, we'll have build coverage
everywhere and test coverage on Chromium, which runs this code on macOS
CI. We should request a macOS ARM64 bot for our standalone CI.  Longer
term, we need a QEMU-based builder to test various features. QEMU seems
to have pretty good coverage of all this, which will at least give us
Linux.

I haven't added an OPENSSL_STATIC_ARMCAP_SHA512 for now. Instead, we
just look at the standard __ARM_FEATURE_SHA512 define. Strangely, the
corresponding -march tag is not sha512. Neither GCC and nor Clang have
-march=armv8-a+sha512. Instead, -march=armv8-a+sha3 implies both
__ARM_FEATURE_SHA3 and __ARM_FEATURE_SHA512! Yet everything else seems
to describe the SHA512 extension as separate from SHA3.
https://developer.arm.com/architectures/system-architectures/software-standards/acle

Update-Note: Consumers with a different build setup may need to
limit -D_XOPEN_SOURCE=700 to Linux or non-Apple platforms. Otherwise,
<sys/types.h> won't define some typedef needed by <sys/sysctl.h>. If you
see a build error about u_char, etc., being undefined in some system
header, that is probably the cause.

Change-Id: Ia213d3796b84c71b7966bb68e0aec92e5d7d26f0
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/50807
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: David Benjamin <davidben@google.com>