From owner-freebsd-dtrace@FreeBSD.ORG Thu Feb 27 08:31:03 2014 Return-Path: Delivered-To: freebsd-dtrace@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 438AED38; Thu, 27 Feb 2014 08:31:03 +0000 (UTC) Received: from mail-qc0-x235.google.com (mail-qc0-x235.google.com [IPv6:2607:f8b0:400d:c01::235]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id E843E1968; Thu, 27 Feb 2014 08:31:02 +0000 (UTC) Received: by mail-qc0-f181.google.com with SMTP id c9so2821119qcz.26 for ; Thu, 27 Feb 2014 00:31:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc:content-type; bh=7peado/iBHPfVfvbYC+hynEqjuitcTtTJX1CC5jir9Y=; b=oNbh8NzKNmFP6X/TnAPWxaxWqiACWyQ3fenw/rES4yCvr0F8qDgmoKa06dlYz7ZwLn DUoWa0Vlu8lFMufTkl5aUDs4hMv7E2dyZIU6S8eiSa3dZi3E2NmNcsmNjqwxb6ssBosj RbJPSjPPOFNiNCXm1lm3HebU89f6R0hC0CSoRsbzzKVs33cGGNaZBHlZmOBQY7Z4wLYQ lLAuhfk6Emh+7ImpXV+BtcsKMZr4pDK6eYdaJ2SmA/MON0saTsCoN3Paw3aH5+xKgMzF OaKMsqGjyqUw+USgObn+VvGwX0u5iMm/WbrUWi8ELsvOY7/D4Dtnpe/8pl/hWEl8Fc0O b1qA== X-Received: by 10.224.80.201 with SMTP id u9mr14306317qak.5.1393489861852; Thu, 27 Feb 2014 00:31:01 -0800 (PST) MIME-Version: 1.0 Sender: fedor.indutny@gmail.com Received: by 10.96.127.74 with HTTP; Thu, 27 Feb 2014 00:30:41 -0800 (PST) In-Reply-To: <20140227050136.GB28089@raichu> References: <20140227050136.GB28089@raichu> From: Fedor Indutny Date: Thu, 27 Feb 2014 12:30:41 +0400 X-Google-Sender-Auth: y1JvPUGVXkIci4CNSEBlvUfheeg Message-ID: Subject: Re: DTrace fixes for node.js To: Mark Johnston Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-dtrace@freebsd.org X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.17 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: Thu, 27 Feb 2014 08:31:03 -0000 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? Cheers, Fedor. 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 >