From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 69F42C5472F for ; Tue, 27 Aug 2024 18:17:31 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D83AE6B008A; Tue, 27 Aug 2024 14:17:30 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D0D3B6B008C; Tue, 27 Aug 2024 14:17:30 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B61056B0092; Tue, 27 Aug 2024 14:17:30 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 904366B008A for ; Tue, 27 Aug 2024 14:17:30 -0400 (EDT) Received: from smtpin07.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 553A5C1B96 for ; Tue, 27 Aug 2024 18:17:30 +0000 (UTC) X-FDA: 82498833060.07.55E238B Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by imf30.hostedemail.com (Postfix) with ESMTP id 0C00B80019 for ; Tue, 27 Aug 2024 18:17:27 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Bgh7QaJ9; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of ebiggers@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=ebiggers@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1724782578; a=rsa-sha256; cv=none; b=HReZsPKQLtxwvTFQXdjvNO4HNTxK2nRddtcwOx52OmY1EZ0l10fvpKfTD6pp+lCMHyvUfw 9UYKxEZGRMb+Do50oDQ9GndAmjcQvYBql2M/0T/LDJpOHhWUvitbkVXuT1apBK7lMbCFQm U/mySLFcUMhZoe979u1quhc5htgOxDo= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=Bgh7QaJ9; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of ebiggers@kernel.org designates 145.40.73.55 as permitted sender) smtp.mailfrom=ebiggers@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1724782578; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HxRN8IVRxXWkwsi5oS0C98gDT/DBYSFNVRgdUtUg1Lw=; b=LYIChpWmkfAmJ3VBJNImsbpz8RkVBLjWfmsFWczoIQk+mlkCw04/x8EYFDvNMCZhKkuKEA caiIkydld4hvIkSvGQEjr9LKcp5HCfH4RQm+hqGHTpKpD2P/xD/tCjXHezgXc1jfBYX6pv tCd2oKRkPAsjRFZpWp9UD7A0weX/Mgk= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 0876DCE13CD; Tue, 27 Aug 2024 18:17:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 370C8C4AF10; Tue, 27 Aug 2024 18:08:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724782102; bh=6hBH/a+6Kb1AQJN1JkfkjXJwDxg0hGfZVyT/Iju2lR4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Bgh7QaJ9At5jwNoKRhsGjGTLpqH2NoHSb2onT69lZKBrg6CFCpd9gW90r+2SgwoH1 0GNU4qRapNNxdtmhiz3gWa+ujq1IlqUkuBPyYN3ra/qXrZ51OrQfDbuWTOriF3MI3u D/yRZfDOKHd3jb7eCXPIUIavEbn8irtpxQkNslY60M5/ftSYmc8YqwalTCS07pFCI3 hj06bAOcQeuQyIFdQ/UkeCFRVRQdnqRPRyQII4nQgYX/4hCQ0YgW5DKAY2h7ICJxTi hD0WPmdZfDXifp12pn1RQcW0W7HncOytAz6KIA0c9HrIIszfZzaAXECJrebhNctsMW /jqTscusJynDA== Date: Tue, 27 Aug 2024 11:08:19 -0700 From: Eric Biggers To: Christophe Leroy Cc: Michael Ellerman , Nicholas Piggin , Naveen N Rao , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Theodore Ts'o , "Jason A. Donenfeld" , Arnd Bergmann , Andrew Morton , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Vincenzo Frascino , Shuah Khan , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 05/17] vdso: Avoid call to memset() by getrandom Message-ID: <20240827180819.GB2049@sol.localdomain> References: <5deb67090b214f0e6eae96b7c406546d1a16f89b.1724309198.git.christophe.leroy@csgroup.eu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5deb67090b214f0e6eae96b7c406546d1a16f89b.1724309198.git.christophe.leroy@csgroup.eu> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 0C00B80019 X-Stat-Signature: ydoex3hpraht3qxzumhtkzjeg9dd13ja X-Rspam-User: X-HE-Tag: 1724782647-750996 X-HE-Meta: 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 iKy0oL5J LMGerj0UhGLFPUZex4SWHwYf82M4bhweNn4lFVRQ7hiE4PK+daF1ZTSmNpLp3OQlZw+B7Qj/zFjGaDBSFYO+pZ7czO0PHT+QdJ6vNNqH3ggCm/H6C95N+9YfPpH9MQGnQKUCU0APBz7wG/lyvk+YPlBqhdoqvHVlt1Pmd2fmg65mu9vw18d4LyfcOuSU9OrWOV3l9FnKw7C5gNrQaANw+/KDFWinLu2t46f5NRUkJv6wLnyV8LzztF3FG5/IutPgsEW5+p+WyNDYlYIY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Aug 22, 2024 at 09:13:13AM +0200, Christophe Leroy wrote: > With the current implementation, __cvdso_getrandom_data() calls > memset(), which is unexpected in the VDSO. > > Rewrite opaque data initialisation to avoid memset(). > > Signed-off-by: Christophe Leroy > --- > lib/vdso/getrandom.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c > index cab153c5f9be..4a56f45141b4 100644 > --- a/lib/vdso/getrandom.c > +++ b/lib/vdso/getrandom.c > @@ -4,6 +4,7 @@ > */ > > #include > +#include > #include > #include > #include > @@ -74,11 +75,15 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_ > u32 counter[2] = { 0 }; > > if (unlikely(opaque_len == ~0UL && !buffer && !len && !flags)) { > - *(struct vgetrandom_opaque_params *)opaque_state = (struct vgetrandom_opaque_params) { > - .size_of_opaque_state = sizeof(*state), > - .mmap_prot = PROT_READ | PROT_WRITE, > - .mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS > - }; > + struct vgetrandom_opaque_params *params = opaque_state; > + int i; > + > + params->size_of_opaque_state = sizeof(*state); > + params->mmap_prot = PROT_READ | PROT_WRITE; > + params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS; > + for (i = 0; i < ARRAY_SIZE(params->reserved); i++) > + params->reserved[i] = 0; > + > return 0; > } Is there a compiler flag that could be used to disable the generation of calls to memset? - Eric