Date: Thu, 27 Feb 2014 09:39:04 -0500 From: Mark Johnston <markj@freebsd.org> To: Fedor Indutny <fedor@indutny.com> Cc: "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> Subject: Re: DTrace fixes for node.js Message-ID: <CAMw1wOwwk8tZxFmxTpV04y04-Dqj9vdDwwprrv2BeQcCtV0z6g@mail.gmail.com> In-Reply-To: <CAEv2Vf%2BHh-K11ika7-awEwFE67OM=Du8Pn9sWvC1cwuVBmSjxw@mail.gmail.com> References: <CAEv2VfLJR7b9Gj7qN9VuuQKWphUUrdJYwQ4r5P%2BKWJYLuddCiA@mail.gmail.com> <20140227050136.GB28089@raichu> <CAEv2Vf%2BHh-K11ika7-awEwFE67OM=Du8Pn9sWvC1cwuVBmSjxw@mail.gmail.com>
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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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