From owner-freebsd-dtrace@FreeBSD.ORG Mon Dec 1 21:54:35 2014 Return-Path: Delivered-To: freebsd-dtrace@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 31733E29 for ; Mon, 1 Dec 2014 21:54:35 +0000 (UTC) Received: from mail-pd0-x22a.google.com (mail-pd0-x22a.google.com [IPv6:2607:f8b0:400e:c02::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id EBF2FDC4 for ; Mon, 1 Dec 2014 21:54:34 +0000 (UTC) Received: by mail-pd0-f170.google.com with SMTP id fp1so11689902pdb.15 for ; Mon, 01 Dec 2014 13:54:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=e4rCuO+zmLg6CWQNkTJ9j6LUDlrQtPkG4VFoxVN0wpc=; b=w1VUGZt0NviokvFrSrEb8vfGT4RqeaNARc7tiBIVBiC5dF/kwr+6tiQ3A97YA2T8P6 Emmaktf0xfcr2lkS0hnAy5k/2KEKxJ2WJLjQzfIv7TBfKYYda0Q/PjxeWRqAZgiH8uL3 SDR/Wx1IRHtPvhtgXp8S7skwdFTflV3IQOObRlj1+KO4d99B75x5gxebVNl2NfwnK4ny jx2QtDmAH+01pp4onm7vL+iXAcViTDaZDN3NOZy19KKqwbe7Fk98kxGnq6+w1AG4+T0L SyV90iA9xtkIO9yQn6B3MCHvtOINrFow4OCnqX/nT/KFuzMu8iAkjeKl/owlqQfX56Rk Cpkg== X-Received: by 10.66.146.135 with SMTP id tc7mr106708275pab.155.1417470874509; Mon, 01 Dec 2014 13:54:34 -0800 (PST) Received: from charmander.picturesperfect.net (c-67-182-131-225.hsd1.wa.comcast.net. [67.182.131.225]) by mx.google.com with ESMTPSA id yc4sm18516358pab.27.2014.12.01.13.54.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 01 Dec 2014 13:54:33 -0800 (PST) Sender: Mark Johnston Date: Mon, 1 Dec 2014 13:54:30 -0800 From: Mark Johnston To: Fedor Indutny Subject: Re: DTrace fixes for node.js Message-ID: <20141201215430.GD48232@charmander.picturesperfect.net> References: <20140227050136.GB28089@raichu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Cc: "freebsd-dtrace@freebsd.org" X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "A discussion list for developers working on DTrace in FreeBSD." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Dec 2014 21:54:35 -0000 On Mon, Dec 01, 2014 at 04:59:02PM +0400, Fedor Indutny wrote: > Hello Mark, DTrace people! > Hi Fedor, > Hope you are doing well. > > Looks like FreeBSD 10.1 decided to play some not that funny games > with drti.c again :) > > I have submitted a [patch][0] as a problem report. Thank you. I'll test and commit it if I don't run into any problems. > > It fixes iteration over aligned DOFs, and accounts for a > non-master-branch FreeBSD stuff in: > > cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c > > Which is currently producing SHT_PROGBITS section instead of > expected SHT_SUNW_dof, thus confusing the drti.c file. Hm, are you referring to this change: https://svnweb.freebsd.org/base?view=revision&revision=271413 ? I'm a bit confused, as it hasn't been merged to 10 yet: it exposed another dtrace bug that caused build failures in some USDT-enabled ports, so I'm waiting for the subsequent fixes to settle. -Mark > > Thank you, > Fedor. > > [0]: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=195555 > > > On Thu, Feb 27, 2014 at 6:50 PM, Fedor Indutny wrote: > > > Update sent, thank you! > > > > On Thu, Feb 27, 2014 at 6:39 PM, Mark Johnston wrote: > > > On Thu, Feb 27, 2014 at 3:30 AM, Fedor Indutny > > wrote: > > >> Mark, > > >> > > >> Thanks for looking into this. I just tried your patch and it (no > > >> surprise) builds fine. Node.js DOF symbols seems to be resolving > > >> properly too! > > >> > > >> Do you want me to squash this changes into my patch, and post them on > > >> that ticket? > > >> > > > > > > That would be good, thanks. When I have some time I'll do more testing > > > and commit the change. > > > > > > -Mark > > > > > >> On Thu, Feb 27, 2014 at 9:01 AM, Mark Johnston > > wrote: > > >>> On Tue, Feb 25, 2014 at 06:16:15PM +0400, Fedor Indutny wrote: > > >>>> Hello devs! > > >>>> > > >>>> I have made some fixes to fix DTrace support for node.js in FreeBSD: > > >>>> > > >>>> * http://www.freebsd.org/cgi/query-pr.cgi?pr=186821 > > >>>> * http://www.freebsd.org/cgi/query-pr.cgi?pr=187027 > > >>>> > > >>>> Here is a blog post with a bit of explanation of why this is needed > > >>>> and what is fixed: https://blog.indutny.com/7.freebsd-dtrace > > >>>> > > >>>> Please let me know if I could be any help in reviewing it. > > >>> > > >>> Hi Fedor, > > >>> > > >>> The DOF limit change looks fine to me. I note that the illumos guys > > have > > >>> just pushed a change to illumos-gate which bumps dtrace_dof_maxsize, > > but > > >>> it's good to have the sysctl as well. > > >>> > > >>> The drti change looks mostly good to me. The real problem there is that > > >>> our linker doesn't know how to merge DOF, so it just concatenates the > > >>> tables into one SUNW_dof section. So we should really fix our linker, > > >>> but it doesn't hurt to also handle the problem in drti.o. > > >>> > > >>> There are a couple of bugs in the patch. First, the "break" added after > > >>> finding the DOF section causes problems if we haven't yet seen the > > >>> symbol table. Second, fixedprobes needs to be reset at the beginning of > > >>> each iteration of the while loop that you added, else we may not try > > >>> searching the dynamic symbol table when fixing the probe addresses. > > I've > > >>> pasted a patch below; could you test it and make sure things still work > > >>> properly with node? > > >>> > > >>> Thanks for the detailed blog post and problem description, they were > > >>> very helpful. :) > > >>> > > >>> -Mark > > >>> > > >>> diff --git a/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c > > b/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c > > >>> index e47cfb4d..bb02d8c 100644 > > >>> --- a/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c > > >>> +++ b/cddl/contrib/opensolaris/lib/libdtrace/common/drti.c > > >>> @@ -162,7 +162,7 @@ dtrace_dof_init(void) > > >>> char *dofstrtabraw; > > >>> size_t shstridx, symtabidx = 0, dynsymidx = 0; > > >>> unsigned char *buf; > > >>> - int fixedprobes = 0; > > >>> + int fixedprobes; > > >>> #endif > > >>> > > >>> if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL) > > >>> @@ -214,7 +214,6 @@ dtrace_dof_init(void) > > >>> if (s && strcmp(s, ".SUNW_dof") == 0) { > > >>> dofdata = elf_getdata(scn, NULL); > > >>> dof = dofdata->d_buf; > > >>> - break; > > >>> } > > >>> } > > >>> } > > >>> @@ -226,6 +225,7 @@ dtrace_dof_init(void) > > >>> } > > >>> > > >>> while ((char *) dof < (char *) dofdata->d_buf + > > dofdata->d_size) { > > >>> + fixedprobes = 0; > > >>> dof_next = (void *) ((char *) dof + dof->dofh_filesz); > > >>> #endif > > >>> > >