On 06/08/2015 07:08 PM, Stephan Mueller wrote:
Hi, I performed measurements of the upper and lower boundary of the minimum and Shannon entropy for the RNG before the patch and after the patch. The values are very similar which demonstrates that the change does not affect the cryptographic characteristics of the RNG. The tests are available at: [1] shows the lower boundary of the fully non-optimized RNG [2] shows the lower boundary of the RNG with the patch below [3] shows the upper boundary of the fully non-optimized RNG [4] shows the upper boundary of the RNG with the patch below The pictures are fully explained in [5], but the key values are the minimum and Shannon entropy numbers in the legend of the graphs. [1] http://www.eperm.de/userspace-foldtime-testO0.data-single-time-dist-delta-3036-hist.pdf [2] http://www.eperm.de/userspace-foldtime-test-pragmas-O2.data-single-time-dist-delta-2370-hist.pdf [3] http://www.eperm.de/userspace-foldtime-testO0.data-varying-time-dist-delta-7302-hist.pdf [4] http://www.eperm.de/userspace-foldtime-test-pragmas-O2.data-varying-time-dist-delta-7055-hist.pdf [5] http://www.chronox.de/jent/doc/CPU-Jitter-NPTRNG.pdf ---8<--- Replace the global -O0 compiler flag from the Makefile with GCC pragmas to mark only the functions required to be compiled without optimizations. This patch also adds a comment describing the rationale for the functions chosen to be compiled without optimizations. Signed-off-by: Stephan Mueller <smueller@xxxxxxxxxx>
With openrisc, I get: CC [M] crypto/jitterentropy.o crypto/jitterentropy.c:266:9: warning: #pragma GCC target is not supported for this machine which may not be perfect, but is better than a compile error ;-). nios2 still fails to build with ERROR: "get_cycles" [crypto/jitterentropy.ko] undefined! Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
