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| author |   Stephan Müller <smueller@chronox.de> | 2021-11-21 15:14:20 +0100 |
|---|---|---|
| committer |   Herbert Xu <herbert@gondor.apana.org.au> | 2021-11-26 16:25:18 +1100 |
| commit | 552d03a223eda3df84526ab2c1f4d82e15eaee7a (patch) | |
| tree | e680fe92fefee834aaadbd5b22ec0b0673ac145f /crypto/rsa.c | |
| parent | crypto: hisilicon/qm - simplified the calculation of qos shaper parameters (diff) | |
| download | wireguard-linux-552d03a223eda3df84526ab2c1f4d82e15eaee7a.tar.xz wireguard-linux-552d03a223eda3df84526ab2c1f4d82e15eaee7a.zip | |
crypto: jitter - consider 32 LSB for APT
The APT compares the current time stamp with a pre-set value. The
current code only considered the 4 LSB only. Yet, after reviews by
mathematicians of the user space Jitter RNG version >= 3.1.0, it was
concluded that the APT can be calculated on the 32 LSB of the time
delta. Thi change is applied to the kernel.
This fixes a bug where an AMD EPYC fails this test as its RDTSC value
contains zeros in the LSB. The most appropriate fix would have been to
apply a GCD calculation and divide the time stamp by the GCD. Yet, this
is a significant code change that will be considered for a future
update. Note, tests showed that constantly the GCD always was 32 on
these systems, i.e. the 5 LSB were always zero (thus failing the APT
since it only considered the 4 LSB for its calculation).
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/rsa.c')
0 files changed, 0 insertions, 0 deletions