From f44fa88745eda1530083b361e300e1ca4e15a6c5 Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Fri, 27 Oct 2017 15:53:49 +0200 Subject: s390/archrandom: Reconsider s390 arch random implementation The reworked version of the random device driver now calls the arch_get_random_* functions on a very high frequency. It does about 100.000 calls to arch_get_random_long for providing 10 MB via /dev/urandom. Each invocation was fetching entropy from the hardware random generator which has a rate limit of about 4 MB/s. As the trng invocation waits until enough entropy is gathered, the random device driver is slowed down dramatically. The s390 true random generator is not designed for such a high rate. The TRNG is more designed to be used together with the arch_get_random_seed_* functions. This is similar to the way how powerpc has implemented their arch random functionality. This patch removes the invocations of the s390 TRNG for arch_get_random_long() and arch_get_random_int() but leaving the invocations for arch_get_random_seed_long() and arch_get_random_seed_int(). So the s390 arch random implementation now contributes high quality entropy to the kernel random device for reseeding. Signed-off-by: Harald Freudenberger Signed-off-by: Heiko Carstens --- arch/s390/include/asm/archrandom.h | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) (limited to 'arch/s390') diff --git a/arch/s390/include/asm/archrandom.h b/arch/s390/include/asm/archrandom.h index 6033901a40b2..9695f8d09edf 100644 --- a/arch/s390/include/asm/archrandom.h +++ b/arch/s390/include/asm/archrandom.h @@ -27,42 +27,42 @@ static void s390_arch_random_generate(u8 *buf, unsigned int nbytes) static inline bool arch_has_random(void) { - if (static_branch_likely(&s390_arch_random_available)) - return true; return false; } static inline bool arch_has_random_seed(void) { - return arch_has_random(); + if (static_branch_likely(&s390_arch_random_available)) + return true; + return false; } static inline bool arch_get_random_long(unsigned long *v) { - if (static_branch_likely(&s390_arch_random_available)) { - s390_arch_random_generate((u8 *)v, sizeof(*v)); - return true; - } return false; } static inline bool arch_get_random_int(unsigned int *v) { - if (static_branch_likely(&s390_arch_random_available)) { - s390_arch_random_generate((u8 *)v, sizeof(*v)); - return true; - } return false; } static inline bool arch_get_random_seed_long(unsigned long *v) { - return arch_get_random_long(v); + if (static_branch_likely(&s390_arch_random_available)) { + s390_arch_random_generate((u8 *)v, sizeof(*v)); + return true; + } + return false; } static inline bool arch_get_random_seed_int(unsigned int *v) { - return arch_get_random_int(v); + if (static_branch_likely(&s390_arch_random_available)) { + s390_arch_random_generate((u8 *)v, sizeof(*v)); + return true; + } + return false; } #endif /* CONFIG_ARCH_RANDOM */ -- cgit