From owner-svn-src-head@FreeBSD.ORG Sun Jun 2 01:05:37 2013 Return-Path: Delivered-To: svn-src-head@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id C09E3C8E; Sun, 2 Jun 2013 01:05:37 +0000 (UTC) (envelope-from markj@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) by mx1.freebsd.org (Postfix) with ESMTP id 992FE799; Sun, 2 Jun 2013 01:05:37 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.6/8.14.6) with ESMTP id r5215bWW062328; Sun, 2 Jun 2013 01:05:37 GMT (envelope-from markj@svn.freebsd.org) Received: (from markj@localhost) by svn.freebsd.org (8.14.6/8.14.5/Submit) id r5215b1p062326; Sun, 2 Jun 2013 01:05:37 GMT (envelope-from markj@svn.freebsd.org) Message-Id: <201306020105.r5215b1p062326@svn.freebsd.org> From: Mark Johnston Date: Sun, 2 Jun 2013 01:05:37 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r251238 - in head/sys/cddl/dev: dtrace/amd64 sdt X-SVN-Group: head 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: 2.1.14 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: Sun, 02 Jun 2013 01:05:37 -0000 Author: markj Date: Sun Jun 2 01:05:36 2013 New Revision: 251238 URL: http://svnweb.freebsd.org/changeset/base/251238 Log: SDT probes can directly pass up to five arguments as arguments to dtrace_probe(). Arguments beyond these five must be obtained in an architecture-specific way; this can be done through the getargval provider method, and through dtrace_getarg() if getargval isn't overridden. This change fixes two off-by-one bugs in the way these arguments are fetched in FreeBSD's DTrace implementation. First, the SDT provider must set the aframes parameter to 1 when creating a probe. The aframes parameter controls the number of frames that dtrace_getarg() will step over in order to find the frame containing the extra arguments. On FreeBSD, dtrace_getarg() is called in SDT probe context via dtrace_probe()->dtrace_dif_emulate()->dtrace_dif_variable->dtrace_getarg() so aframes must be 3 since the arguments are in dtrace_probe()'s frame; it was previously being called with a value of 2 instead. illumos uses a different aframes value for SDT probes, but this is because illumos SDT probes fire by triggering the #UD fault handler rather than calling dtrace_probe() directly. The second bug has to do with the way arguments are grabbed out dtrace_probe()'s frame on amd64. The code currently jumps over the first stack argument and retrieves the rest of them using a pointer into the stack. This works on i386 because all of dtrace_probe()'s arguments will be on the stack and the first argument is the probe ID, which should be ignored. However, it is incorrect to ignore the first stack argument on amd64, so we correct the pointer used to access the arguments. MFC after: 2 weeks Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c head/sys/cddl/dev/sdt/sdt.c Modified: head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c ============================================================================== --- head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c Sun Jun 2 00:33:36 2013 (r251237) +++ head/sys/cddl/dev/dtrace/amd64/dtrace_isa.c Sun Jun 2 01:05:36 2013 (r251238) @@ -398,7 +398,7 @@ dtrace_getarg(int arg, int aframes) } arg -= (inreg + 1); - stack = (uintptr_t *)&fp[1]; + stack = (uintptr_t *)fp + 2; load: DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT); Modified: head/sys/cddl/dev/sdt/sdt.c ============================================================================== --- head/sys/cddl/dev/sdt/sdt.c Sun Jun 2 00:33:36 2013 (r251237) +++ head/sys/cddl/dev/sdt/sdt.c Sun Jun 2 01:05:36 2013 (r251238) @@ -134,7 +134,7 @@ sdt_probe_callback(struct sdt_probe *pro return (0); (void) dtrace_probe_create(prov->id, probe->mod, probe->func, - probe->name, 0, probe); + probe->name, 1, probe); return (0); }