From owner-svn-src-all@freebsd.org Sun May 12 06:32:47 2019 Return-Path: <owner-svn-src-all@freebsd.org> Delivered-To: svn-src-all@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id B567D158DF6A; Sun, 12 May 2019 06:32:47 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 5680C8A233; Sun, 12 May 2019 06:32:47 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 2B74F26E54; Sun, 12 May 2019 06:32:47 +0000 (UTC) (envelope-from mjg@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id x4C6WkBF093872; Sun, 12 May 2019 06:32:46 GMT (envelope-from mjg@FreeBSD.org) Received: (from mjg@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id x4C6Wkmr093871; Sun, 12 May 2019 06:32:46 GMT (envelope-from mjg@FreeBSD.org) Message-Id: <201905120632.x4C6Wkmr093871@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: mjg set sender to mjg@FreeBSD.org using -f From: Mateusz Guzik <mjg@FreeBSD.org> Date: Sun, 12 May 2019 06:32:46 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r347500 - head/sys/libkern X-SVN-Group: head X-SVN-Commit-Author: mjg X-SVN-Commit-Paths: head/sys/libkern X-SVN-Commit-Revision: 347500 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 5680C8A233 X-Spamd-Bar: -- Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-2.91 / 15.00]; local_wl_from(0.00)[FreeBSD.org]; NEURAL_HAM_MEDIUM(-1.00)[-0.996,0]; NEURAL_HAM_SHORT(-0.91)[-0.913,0]; ASN(0.00)[asn:11403, ipnet:2610:1c1:1::/48, country:US]; NEURAL_HAM_LONG(-1.00)[-1.000,0] X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" <svn-src-all.freebsd.org> List-Unsubscribe: <https://lists.freebsd.org/mailman/options/svn-src-all>, <mailto:svn-src-all-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all/> List-Post: <mailto:svn-src-all@freebsd.org> List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help> List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/svn-src-all>, <mailto:svn-src-all-request@freebsd.org?subject=subscribe> X-List-Received-Date: Sun, 12 May 2019 06:32:47 -0000 Author: mjg Date: Sun May 12 06:32:46 2019 New Revision: 347500 URL: https://svnweb.freebsd.org/changeset/base/347500 Log: random(4): depessimize arc4random - __predict_false reseeding on entry as it is almost never true. - don't blindly atomic_cmpset as on x86 it ends up dirtying the cacheline. it almost ever succeeds per above - fetch the timestamp prior to getting the cpu number Reviewed by: cem Approved by: secteam (delphij) Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D20242 Modified: head/sys/libkern/arc4random.c Modified: head/sys/libkern/arc4random.c ============================================================================== --- head/sys/libkern/arc4random.c Sat May 11 22:58:25 2019 (r347499) +++ head/sys/libkern/arc4random.c Sun May 12 06:32:46 2019 (r347500) @@ -173,18 +173,20 @@ arc4rand(void *ptr, u_int len, int reseed) u_int length; u_int8_t *p; - if (reseed || atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED)) + if (__predict_false(reseed || + (arc4rand_iniseed_state == ARC4_ENTR_HAVE && + atomic_cmpset_int(&arc4rand_iniseed_state, ARC4_ENTR_HAVE, ARC4_ENTR_SEED)))) CHACHA20_FOREACH(chacha20) chacha20_randomstir(chacha20); - chacha20 = &chacha20inst[curcpu]; getmicrouptime(&tv); + chacha20 = &chacha20inst[curcpu]; /* We may get unlucky and be migrated off this CPU, but that is expected to be infrequent */ if ((chacha20->numbytes > CHACHA20_RESEED_BYTES) || (tv.tv_sec > chacha20->t_reseed)) chacha20_randomstir(chacha20); - mtx_lock(&chacha20->mtx); p = ptr; + mtx_lock(&chacha20->mtx); while (len) { length = MIN(CHACHA20_BUFFER_SIZE, len); chacha_encrypt_bytes(&chacha20->ctx, chacha20->m_buffer, p, length);