RE: kdf108_init() takes over 250 ms

[Elliott, Robert (Servers)]

> -----Original Message-----
> From: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
> Sent: Tuesday, August 23, 2022 9:52 AM
> To: Stephan Müller <smueller@xxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>; David S. Miller
> <davem@xxxxxxxxxxxxx>; linux-crypto@xxxxxxxxxxxxxxx; LKML <linux-
> kernel@xxxxxxxxxxxxxxx>
> Subject: kdf108_init() takes over 250 ms
> 
> Dear Stephan,
> 
> On the Dell XPS 13 9370 with Debian sid/unstable, I noticed with Linux
> 5.18.16, that  `crypto_kdf108_init()` takes 263 ms to run even with
> disabled self-tests:
> 
...
> [    0.000000] Command line: BOOT_IMAGE=/vmlinuz-5.18.0-4-amd64
> root=UUID=56f398e0-1e25-4fda-aa9f-611dece4b333 ro quiet
> module_blacklist=psmouse initcall_debug log_buf_len=4M cryptomgr.notests
...
> [    0.272127] calling  crypto_kdf108_init+0x0/0x149 @ 1
> [    0.530787] Freeing initrd memory: 39332K
> [    0.534667] alg: self-tests disabled
> [    0.534701] alg: self-tests for CTR-KDF (hmac(sha256)) passed
> [    0.534703] initcall crypto_kdf108_init+0x0/0x149 returned 0 after
> 262573 usecs
...
> 
> With self-tests enabled it’s only less than a millisecond longer.
> 
> ```
> [    0.282389] calling  crypto_kdf108_init+0x0/0x149 @ 1
> [    0.541096] Freeing initrd memory: 39332K
> [    0.545674] alg: self-tests for CTR-KDF (hmac(sha256)) passed
> [    0.545676] initcall crypto_kdf108_init+0x0/0x149 returned 0 after
> 263284 usecs
> ```

crypto_kdf108_init() call its self-test function directly rather
that alg_test(), which implements that notests flag. Maybe it
should go through alg_test().

Outside of that, check that Tim's x86-optimized SHA-256 module
is loaded, so it is used rather than the generic implementation.
One my system, that improves the kdf108 initialization time 
from 1.4 s to 0.38 s:

With sha256_generic:
  initcall sha256_generic_mod_init+0x0/0x16 returned 0 after 0 usecs
  ...
  initcall crypto_kdf108_init+0x0/0x18d returned 0 after 1425640 usecs

With sha256_ssse3 (using its AVX2 implementation):
  initcall sha256_ssse3_mod_init+0x0/0x1bf returned 0 after 12148 usecs
  ...
  initcall crypto_kdf108_init+0x0/0x153 returned 0 after 382799 usecs

That's controlled by CONFIG_CRYPTO_SHA256_SSSE3.