From owner-freebsd-dtrace@FreeBSD.ORG Mon Dec 1 12:59:24 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 TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id A7001362; Mon, 1 Dec 2014 12:59:24 +0000 (UTC) Received: from mail-wi0-x236.google.com (mail-wi0-x236.google.com [IPv6:2a00:1450:400c:c05::236]) (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 3D32DAF9; Mon, 1 Dec 2014 12:59:24 +0000 (UTC) Received: by mail-wi0-f182.google.com with SMTP id h11so17210116wiw.15 for ; Mon, 01 Dec 2014 04:59:22 -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=LjxGp2pI6IkY3FLs58kUw5k9kjjuRBXWm97ZQjlcNCs=; b=eLNbAu8UwzxqgkTMT3TLuYqVfnBIrKP7P4iLrAfjx3TM7CPa1DDBC53NkZb/CsrLss qXb1YI39ZkkmkJtlRtkLrm55O/+D8srR0sd0U82PczsV5MGa8bbE0reDyCtJBNFhNY8J Ww8Ps/mkTYcou0UDf6YF3I85Kein14IjcR6+dVppUACgQo6SMttk6xRHseR7+kPEhBb7 j73Ey439i/VZ8ZDY4D/jeMpOuheTogA43YLndQ6W5cwpO0F1DiFyMPz9zRYPFx+bh+fs iKO/v41mXUmm+H0/L959rT7YYWBysho9rRDqZHrOW8EgPrcyM0OHjfS4iWeVVahBf7wt UGmg== X-Received: by 10.194.120.164 with SMTP id ld4mr94390897wjb.67.1417438762466; Mon, 01 Dec 2014 04:59:22 -0800 (PST) MIME-Version: 1.0 Sender: fedor.indutny@gmail.com Received: by 10.27.48.2 with HTTP; Mon, 1 Dec 2014 04:59:02 -0800 (PST) In-Reply-To: References: <20140227050136.GB28089@raichu> From: Fedor Indutny Date: Mon, 1 Dec 2014 16:59:02 +0400 X-Google-Sender-Auth: -Cv9IljLsiZ5LZwRI4SQMkMgOvs Message-ID: Subject: Re: DTrace fixes for node.js To: Mark Johnston Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.18-1 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 12:59:24 -0000 Hello Mark, DTrace people! 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. 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. 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 > >>> >