From owner-svn-src-head@freebsd.org Mon Dec 18 17:26:26 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 56D9CE9D90C; Mon, 18 Dec 2017 17:26:26 +0000 (UTC) (envelope-from markj@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 mx1.freebsd.org (Postfix) with ESMTPS id 236C565AB8; Mon, 18 Dec 2017 17:26:26 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id vBIHQPH6013175; Mon, 18 Dec 2017 17:26:25 GMT (envelope-from markj@FreeBSD.org) Received: (from markj@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id vBIHQPor013173; Mon, 18 Dec 2017 17:26:25 GMT (envelope-from markj@FreeBSD.org) Message-Id: <201712181726.vBIHQPor013173@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: markj set sender to markj@FreeBSD.org using -f From: Mark Johnston Date: Mon, 18 Dec 2017 17:26:25 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r326935 - in head/sys/cddl/dev/dtrace: amd64 i386 X-SVN-Group: head X-SVN-Commit-Author: markj X-SVN-Commit-Paths: in head/sys/cddl/dev/dtrace: amd64 i386 X-SVN-Commit-Revision: 326935 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Dec 2017 17:26:26 -0000 Author: markj Date: Mon Dec 18 17:26:24 2017 New Revision: 326935 URL: https://svnweb.freebsd.org/changeset/base/326935 Log: Avoid CPU migration in dtrace_gethrtime() on x86. dtrace_gethrtime() may be called outside of probe context, and in particular, from the DTRACEIOC_BUFSNAP handler. Disable interrupts rather than using sched_pin() to help ensure that we don't call any external functions when in probe context. PR: 218452 MFC after: 1 week Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c ============================================================================== --- head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Mon Dec 18 17:17:07 2017 (r326934) +++ head/sys/cddl/dev/dtrace/amd64/dtrace_subr.c Mon Dec 18 17:26:24 2017 (r326935) @@ -353,11 +353,11 @@ SYSINIT(dtrace_gethrtime_init, SI_SUB_SMP, SI_ORDER_AN * Returns nanoseconds since boot. */ uint64_t -dtrace_gethrtime() +dtrace_gethrtime(void) { uint64_t tsc; - uint32_t lo; - uint32_t hi; + uint32_t lo, hi; + register_t rflags; /* * We split TSC value into lower and higher 32-bit halves and separately @@ -365,7 +365,10 @@ dtrace_gethrtime() * (see nsec_scale calculations) taking into account 32-bit shift of * the higher half and finally add. */ + rflags = intr_disable(); tsc = rdtsc() - tsc_skew[curcpu]; + intr_restore(rflags); + lo = tsc; hi = tsc >> 32; return (((lo * nsec_scale) >> SCALE_SHIFT) + Modified: head/sys/cddl/dev/dtrace/i386/dtrace_subr.c ============================================================================== --- head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Mon Dec 18 17:17:07 2017 (r326934) +++ head/sys/cddl/dev/dtrace/i386/dtrace_subr.c Mon Dec 18 17:26:24 2017 (r326935) @@ -355,11 +355,11 @@ SYSINIT(dtrace_gethrtime_init, SI_SUB_SMP, SI_ORDER_AN * Returns nanoseconds since boot. */ uint64_t -dtrace_gethrtime() +dtrace_gethrtime(void) { uint64_t tsc; - uint32_t lo; - uint32_t hi; + uint32_t lo, hi; + register_t eflags; /* * We split TSC value into lower and higher 32-bit halves and separately @@ -367,7 +367,10 @@ dtrace_gethrtime() * (see nsec_scale calculations) taking into account 32-bit shift of * the higher half and finally add. */ + eflags = intr_disable(); tsc = rdtsc() - tsc_skew[curcpu]; + intr_restore(eflags); + lo = tsc; hi = tsc >> 32; return (((lo * nsec_scale) >> SCALE_SHIFT) +