random: Use arch_get_random_seed*() at init time and once a second
Use arch_get_random_seed*() in two places in the Linux random
driver (drivers/char/random.c):
1. During entropy pool initialization, use RDSEED in favor of RDRAND,
with a fallback to the latter. Entropy exhaustion is unlikely to
happen there on physical hardware as the machine is single-threaded
at that point, but could happen in a virtual machine. In that
case, the fallback to RDRAND will still provide more than adequate
entropy pool initialization.
2. Once a second, issue RDSEED and, if successful, feed it to the
entropy pool. To ensure an extra layer of security, only credit
half the entropy just in case.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
1 file changed