From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752866AbaCRDpE (ORCPT ); Mon, 17 Mar 2014 23:45:04 -0400 Received: from gate.crashing.org ([63.228.1.57]:38517 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751534AbaCRDpD (ORCPT ); Mon, 17 Mar 2014 23:45:03 -0400 Message-ID: <1395114240.15098.205.camel@pasglop> Subject: Re: [PATCH v2 4/4] random: Add arch_has_random[_seed]() From: Benjamin Herrenschmidt To: "H. Peter Anvin" Cc: "Ted Ts'o" , Linus Torvalds , Ingo Molnar , Thomas Gleixner , Paul Mackerras , Michael Ellerman , Linux Kernel Mailing List Date: Tue, 18 Mar 2014 14:44:00 +1100 In-Reply-To: <1395099390-807-5-git-send-email-hpa@linux.intel.com> References: <1395099390-807-1-git-send-email-hpa@linux.intel.com> <1395099390-807-5-git-send-email-hpa@linux.intel.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.11.90 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2014-03-17 at 16:36 -0700, H. Peter Anvin wrote: > Add predicate functions for having arch_get_random[_seed]*(). The > only current use is to avoid the loop in arch_random_refill() when > arch_get_random_seed_long() is unavailable. Paul, I think our HW rng on P7+ and later would qualify no ? Cheers, Ben. > Signed-off-by: H. Peter Anvin > Cc: Benjamin Herrenschmidt > Cc: Paul Mackerras > Cc: Michael Ellerman > --- > arch/powerpc/include/asm/archrandom.h | 9 +++++++++ > arch/x86/include/asm/archrandom.h | 3 +++ > drivers/char/random.c | 3 +++ > include/linux/random.h | 8 ++++++++ > 4 files changed, 23 insertions(+) > > diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h > index 801beba..bde5311 100644 > --- a/arch/powerpc/include/asm/archrandom.h > +++ b/arch/powerpc/include/asm/archrandom.h > @@ -25,6 +25,11 @@ static inline int arch_get_random_int(unsigned int *v) > return rc; > } > > +static inline int arch_has_random(void) > +{ > + return !!ppc_md.get_random_long; > +} > + > int powernv_get_random_long(unsigned long *v); > > static inline int arch_get_random_seed_long(unsigned long *v) > @@ -35,6 +40,10 @@ static inline int arch_get_random_seed_int(unsigned int *v) > { > return 0; > } > +static inline int arch_has_random_seed(void) > +{ > + return 0; > +} > > #endif /* CONFIG_ARCH_RANDOM */ > > diff --git a/arch/x86/include/asm/archrandom.h b/arch/x86/include/asm/archrandom.h > index ba064d5..c7ed4a6 100644 > --- a/arch/x86/include/asm/archrandom.h > +++ b/arch/x86/include/asm/archrandom.h > @@ -100,6 +100,9 @@ GET_SEED(arch_get_random_seed_int, unsigned int, RDSEED_INT, ASM_NOP4); > > #endif /* CONFIG_X86_64 */ > > +#define arch_has_random() static_cpu_has(X86_FEATURE_RDRAND) > +#define arch_has_random_seed() static_cpu_has(X86_FEATURE_RDSEED) > + > #endif /* CONFIG_ARCH_RANDOM */ > > extern void x86_init_rdrand(struct cpuinfo_x86 *c); > diff --git a/drivers/char/random.c b/drivers/char/random.c > index c35cee2..6b75713 100644 > --- a/drivers/char/random.c > +++ b/drivers/char/random.c > @@ -1307,6 +1307,9 @@ static int arch_random_refill(void) > unsigned int i; > unsigned long buf[nlongs]; > > + if (!arch_has_random_seed()) > + return 0; > + > for (i = 0; i < nlongs; i++) { > if (arch_get_random_seed_long(&buf[n])) > n++; > diff --git a/include/linux/random.h b/include/linux/random.h > index ddaddec..e7a221a 100644 > --- a/include/linux/random.h > +++ b/include/linux/random.h > @@ -72,6 +72,10 @@ static inline int arch_get_random_int(unsigned int *v) > { > return 0; > } > +static inline int arch_has_random(void) > +{ > + return 0; > +} > static inline int arch_get_random_seed_long(unsigned long *v) > { > return 0; > @@ -80,6 +84,10 @@ static inline int arch_get_random_seed_int(unsigned int *v) > { > return 0; > } > +static inline int arch_has_random_seed(void) > +{ > + return 0; > +} > #endif > > /* Pseudo random number generator from numerical recipes. */