tree 31310dd9ee63dd6cd498c46ee4a87b697dfced32
parent 94a608a1f5d4339d95252902a9e9381c2cc1c225
author Adam Langley <alangley@gmail.com> 1625096027 -0700
committer Boringssl LUCI CQ <boringssl-scoped@luci-project-accounts.iam.gserviceaccount.com> 1626376721 +0000

hrss: use less stack space.

The stack consumption of the HRSS functions is causing issues in
stack-constrained environments. Therefore allocate many variables on the
heap. This means that several HRSS_ functions now allocate, and thus can
fail, where they couldn't before. Callers that ignore the return value
and don't have crash-on-failure mallocs will still be safe, although
things will fail to decrypt later on.

Somehow, this actually makes key generation _faster_ on my machine. (I
don't know. Better alignment? Fewer L1 collisions?) The other operations
are slightly slower, as expected.

Before:

Did 17390 HRSS generate operations in 3054088us (5694.0 ops/sec)
Did 225000 HRSS encap operations in 3000512us (74987.2 ops/sec)
Did 87000 HRSS decap operations in 3014525us (28860.3 ops/sec)

After:

Did 21300 HRSS generate operations in 3026637us (7037.5 ops/sec)
Did 221000 HRSS encap operations in 3008911us (73448.5 ops/sec)
Did 84000 HRSS decap operations in 3007622us (27929.0 ops/sec)

Change-Id: I2312df8909af7d8d250c7c483c65038123f21ad9
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/48345
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: David Benjamin <davidben@google.com>