On Fri, Sep 13, 2024 at 03:05:43PM +0200, Heiko Carstens wrote: > Provide the s390 specific vdso getrandom() architecture backend. > > _vdso_rng_data required data is placed within the _vdso_data vvar page, by > using a hardcoded offset larger than vdso_data. > > As required the chacha20 implementation does not write to the stack. > > The implementation follows more or less the arm64 implementations and > makes use of vector instructions. It has a fallback to the getrandom() > system call for machines where the vector facility is not > installed. > The check if the vector facility is installed, as well as an > optimization for machines with the vector-enhancements facility 2, > is implemented with alternatives, avoiding runtime checks. > > Note that __kernel_getrandom() is implemented without the vdso user wrapper > which would setup a stack frame for odd cases (aka very old glibc variants) > where the caller has not done that. All callers of __kernel_getrandom() are > required to setup a stack frame, like the C ABI requires it. > > The vdso testcases vdso_test_getrandom and vdso_test_chacha pass. I'd be curious to see the results of ./vdso_test_getrandom bench-single and such. Jason
