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authorHarald Freudenberger <freude@linux.vnet.ibm.com>2017-10-27 15:53:49 +0200
committerHeiko Carstens <heiko.carstens@de.ibm.com>2017-11-08 09:47:51 +0100
commitf44fa88745eda1530083b361e300e1ca4e15a6c5 (patch)
treee71acb270f3b118f2a3d70b5e8d69f4c2395fd6c /arch/s390/include/asm/archrandom.h
parent48070c73058be6de9c0d754d441ed7092dfc8f12 (diff)
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 <freude@linux.vnet.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/archrandom.h')
-rw-r--r--arch/s390/include/asm/archrandom.h26
1 files changed, 13 insertions, 13 deletions
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 */

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