From owner-freebsd-dtrace@FreeBSD.ORG Thu Feb 27 14:39:06 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 DFEFE740 for ; Thu, 27 Feb 2014 14:39:05 +0000 (UTC) Received: from mail-ve0-x231.google.com (mail-ve0-x231.google.com [IPv6:2607:f8b0:400c:c01::231]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 9707E10CF for ; Thu, 27 Feb 2014 14:39:05 +0000 (UTC) Received: by mail-ve0-f177.google.com with SMTP id sa20so581098veb.22 for ; Thu, 27 Feb 2014 06:39:04 -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:date:message-id:subject :from:to:cc:content-type; bh=+THNUcuVbEKYf0RnUPF650RjWiowYTPV2fHw9NHY7mg=; b=LNlaSe7y0KKjznJ6Isyo0fUS1WZmNDzyJF5vh2JKFa4de2ZIf/L1T8kbIFri+taBS2 W+C6gSp/RBYnXrPuBb7HlfWxEkptfhYTm5wj0jUHMeb6Sft6Em5SLgp4KfcOy72Wtr7s XecrBYHeFCqMs3DTgvgAhek/90qLXNFyMScjf8okokdyS0S2gHA8t3NKlUFo2or5MFcT Lfra8Z1YYn+s5+d0/Y86dwT57Y5pZgTADZTaWhH11NGKf3bFdhKz5sQUtyMFNYaYi0B6 8uLePfPcv3/wgvmxzW66IRgzfA7fpquqlSfsNA6vyJZL/JfHMDVBTYn63pcmPZy6/aA0 pdxg== MIME-Version: 1.0 X-Received: by 10.220.95.139 with SMTP id d11mr10948796vcn.21.1393511944598; Thu, 27 Feb 2014 06:39:04 -0800 (PST) Sender: markjdb@gmail.com Received: by 10.220.162.68 with HTTP; Thu, 27 Feb 2014 06:39:04 -0800 (PST) In-Reply-To: References: <20140227050136.GB28089@raichu> Date: Thu, 27 Feb 2014 09:39:04 -0500 X-Google-Sender-Auth: wGZIKjfrFN2rPTGyr2TPaxxSQQU Message-ID: Subject: Re: DTrace fixes for node.js From: Mark Johnston To: Fedor Indutny 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 14:39:06 -0000 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 >>