From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:39694 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731589AbfJJCwk (ORCPT ); Wed, 9 Oct 2019 22:52:40 -0400 Date: Thu, 10 Oct 2019 10:52:29 +0800 From: Dave Young Subject: Re: [PATCH] lib/string: make memzero_explicit inline instead of external Message-ID: <20191010025229.GA3376@dhcp-128-65.nay.redhat.com> References: <1d17349e-98ab-b582-6981-b484b0e970b6@redhat.com> <20191007220000.GA408752@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191007220000.GA408752@rani.riverdale.lan> Sender: linux-s390-owner@vger.kernel.org List-ID: To: Arvind Sankar Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Hans de Goede , linux-crypto@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Herbert Xu , Ard Biesheuvel , Stephan Mueller , kexec@lists.infradead.org On 10/07/19 at 06:00pm, Arvind Sankar wrote: > With the use of the barrier implied by barrier_data(), there is no need > for memzero_explicit to be extern. Making it inline saves the overhead > of a function call, and allows the code to be reused in arch/*/purgatory > without having to duplicate the implementation. > > Fixes: 906a4bb97f5d ("crypto: sha256 - Use get/put_unaligned_be32 to get input, memzero_explicit") > Reviewed-by: Hans de Goede > Tested-by: Hans de Goede > Signed-off-by: Arvind Sankar > --- > include/linux/string.h | 21 ++++++++++++++++++++- > lib/string.c | 21 --------------------- > 2 files changed, 20 insertions(+), 22 deletions(-) > > diff --git a/include/linux/string.h b/include/linux/string.h > index b2f9df7f0761..b6ccdc2c7f02 100644 > --- a/include/linux/string.h > +++ b/include/linux/string.h > @@ -227,7 +227,26 @@ static inline bool strstarts(const char *str, const char *prefix) > } > > size_t memweight(const void *ptr, size_t bytes); > -void memzero_explicit(void *s, size_t count); > + > +/** > + * memzero_explicit - Fill a region of memory (e.g. sensitive > + * keying data) with 0s. > + * @s: Pointer to the start of the area. > + * @count: The size of the area. > + * > + * Note: usually using memset() is just fine (!), but in cases > + * where clearing out _local_ data at the end of a scope is > + * necessary, memzero_explicit() should be used instead in > + * order to prevent the compiler from optimising away zeroing. > + * > + * memzero_explicit() doesn't need an arch-specific version as > + * it just invokes the one of memset() implicitly. > + */ > +static inline void memzero_explicit(void *s, size_t count) > +{ > + memset(s, 0, count); > + barrier_data(s); > +} > > /** > * kbasename - return the last part of a pathname. > diff --git a/lib/string.c b/lib/string.c > index cd7a10c19210..08ec58cc673b 100644 > --- a/lib/string.c > +++ b/lib/string.c > @@ -748,27 +748,6 @@ void *memset(void *s, int c, size_t count) > EXPORT_SYMBOL(memset); > #endif > > -/** > - * memzero_explicit - Fill a region of memory (e.g. sensitive > - * keying data) with 0s. > - * @s: Pointer to the start of the area. > - * @count: The size of the area. > - * > - * Note: usually using memset() is just fine (!), but in cases > - * where clearing out _local_ data at the end of a scope is > - * necessary, memzero_explicit() should be used instead in > - * order to prevent the compiler from optimising away zeroing. > - * > - * memzero_explicit() doesn't need an arch-specific version as > - * it just invokes the one of memset() implicitly. > - */ > -void memzero_explicit(void *s, size_t count) > -{ > - memset(s, 0, count); > - barrier_data(s); > -} > -EXPORT_SYMBOL(memzero_explicit); > - > #ifndef __HAVE_ARCH_MEMSET16 > /** > * memset16() - Fill a memory area with a uint16_t > -- Thanks for the fix! Ccing kexec list since the problem is kexec/kdump related. People can try it when they see same issue. Dave