Date: Thu, 27 Feb 2014 18:50:06 +0400 From: Fedor Indutny <fedor@indutny.com> To: Mark Johnston <markj@freebsd.org> Cc: "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> Subject: Re: DTrace fixes for node.js Message-ID: <CAEv2VfL9h4FUaFgDGCMDuQ_1d3tK3K_e19bBw3kvD0hun4P=Kg@mail.gmail.com> In-Reply-To: <CAMw1wOwwk8tZxFmxTpV04y04-Dqj9vdDwwprrv2BeQcCtV0z6g@mail.gmail.com> References: <CAEv2VfLJR7b9Gj7qN9VuuQKWphUUrdJYwQ4r5P%2BKWJYLuddCiA@mail.gmail.com> <20140227050136.GB28089@raichu> <CAEv2Vf%2BHh-K11ika7-awEwFE67OM=Du8Pn9sWvC1cwuVBmSjxw@mail.gmail.com> <CAMw1wOwwk8tZxFmxTpV04y04-Dqj9vdDwwprrv2BeQcCtV0z6g@mail.gmail.com>
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Update sent, thank you! On Thu, Feb 27, 2014 at 6:39 PM, Mark Johnston <markj@freebsd.org> wrote: > On Thu, Feb 27, 2014 at 3:30 AM, Fedor Indutny <fedor@indutny.com> 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 <markj@freebsd.org> 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 >>>
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