Date: Tue, 12 Nov 2013 12:03:05 +0800 (SGT) From: Prashanth Kumar <pra_udupi@yahoo.co.in> To: "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> Message-ID: <1384228985.51085.YahooMailNeo@web192604.mail.sg3.yahoo.com>
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Hello, =0A=0AI had been doing some work on the pid provider in Dtrace.I hav= e made a few modification=0A=A0so that it will list all the functions used = in the program as seen in Solaris or MacOSX.=0A=A0Presently in FreeBSD, you= have to name each functions you have to probe in the program. For=0A=A0exa= mple "dtrace -n 'pid$target:program::entry' -c ./program" will list all the= functions called=0A=A0in the program.This modification was made in libproc= library(proc_sym.c).=0A=0A=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Also while cre= ating probe points for return probe type, any function with more than one r= eturn=0A=A0path will fail.This is because "fasttrap_probe_spec_t" type vari= able is not fully copied into the=0A=A0kernel in fasttrap_ioctl() function.= I have modified in line with Solaris code where the copying=A0 is=0A=A0done= manually by Dtrace, rather than the kernel.(fasttap.c, fasttrap.h)=0A=A0Al= so in "fasttrap_pid_probe()" (fasttrap_isa.c) for the case of "FASTTRAP_T_P= USHL_EBP", the ebp register=0A=A0has to be copied to the stack not esp.=0A= =A0=A0=A0=A0=A0=A0=A0 I had attached the patch files for review.=0A=0A=A0On= e other issue i noticed is that if the program being traced uses Thread Loc= al Storage than=0A=A0for the case of entry probe, it will hang in ___tls_ge= t_addr function in ld-elf.so.=0A=A0If you use scanf or fscanf in your progr= am you can notice this behaviour. This i believe is due to=0A=A0Dtrace usin= g gs segment register to point to the scratch space, and TLS also loading t= he thread variable=0A=A0from gs register.=0A=0A=A0if you change the followi= ng code in fasttrap_isa.c=0A=A0<code>=0A=A0#ifdef __i386__=0A=A0=A0=A0=A0= =A0=A0=A0=A0 addr =3D USD_GETBASE(&curthread->td_pcb->pcb_gsd);=0A=A0#else= =0A=A0=A0=A0=A0=A0=A0=A0=A0 addr =3D curthread->td_pcb->pcb_gsbase;=0A=A0#e= ndif=0A=A0=A0=A0=A0=A0=A0=A0=A0 addr +=3D sizeof (void *);=A0 =A0=0A=A0</co= de>=0A=0A=A0to=0A=0A=A0<code>=0A=A0#ifdef __i386__=0A=A0=A0=A0=A0=A0=A0=A0= =A0 addr =3D USD_GETBASE(&curthread->td_pcb->pcb_gsd);=0A=A0#else=0A=A0=A0= =A0=A0=A0=A0=A0=A0 addr =3D curthread->td_pcb->pcb_gsbase;=0A=A0#endif=0A= =A0=A0=A0=A0=A0=A0=A0=A0 addr +=3D sizeof (void *) * 3;=A0 =A0=0A=A0</code>= =0A=0A=A0the Dtrace will not hang. I am not sure what is happening here and= =0A=A0whether this is the correct solution.=0A=A0This changes were made in = FreeBSD 9.2-386-RELEASE. I applied the above patches on=0A=A0FreeBSD 10-BET= A (with some manual work) and it was still working. 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[24.212.218.13]) by mx.google.com with ESMTPSA id f5sm22528908igc.4.2013.11.11.20.18.09 for <multiple recipients> (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 11 Nov 2013 20:18:10 -0800 (PST) Sender: Mark Johnston <markjdb@gmail.com> Date: Mon, 11 Nov 2013 23:18:05 -0500 From: Mark Johnston <markj@freebsd.org> To: Prashanth Kumar <pra_udupi@yahoo.co.in> Subject: Re: your mail Message-ID: <20131112041805.GA76413@raichu> References: <1384228985.51085.YahooMailNeo@web192604.mail.sg3.yahoo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1384228985.51085.YahooMailNeo@web192604.mail.sg3.yahoo.com> User-Agent: Mutt/1.5.21 (2010-09-15) Cc: "freebsd-dtrace@freebsd.org" <freebsd-dtrace@freebsd.org> X-BeenThere: freebsd-dtrace@freebsd.org X-Mailman-Version: 2.1.16 Precedence: list List-Id: "A discussion list for developers working on DTrace in FreeBSD." <freebsd-dtrace.freebsd.org> List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-dtrace>, <mailto:freebsd-dtrace-request@freebsd.org?subject=unsubscribe> List-Archive: <http://lists.freebsd.org/pipermail/freebsd-dtrace/>; List-Post: <mailto:freebsd-dtrace@freebsd.org> List-Help: <mailto:freebsd-dtrace-request@freebsd.org?subject=help> List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-dtrace>, <mailto:freebsd-dtrace-request@freebsd.org?subject=subscribe> X-List-Received-Date: Tue, 12 Nov 2013 04:18:13 -0000 On Tue, Nov 12, 2013 at 12:03:05PM +0800, Prashanth Kumar wrote: > Hello, > > I had been doing some work on the pid provider in Dtrace. Hi Prashanth, I've been going through your patches and committing them as time permits. > I have made a few modification > so that it will list all the functions used in the program as seen in Solaris or MacOSX. > Presently in FreeBSD, you have to name each functions you have to probe in the program. For > example "dtrace -n 'pid$target:program::entry' -c ./program" will list all the functions called > in the program.This modification was made in libproc library(proc_sym.c). This has been fixed: http://svnweb.freebsd.org/base?view=revision&revision=257300 http://svnweb.freebsd.org/base?view=revision&revision=258000 > > Also while creating probe points for return probe type, any function with more than one return > path will fail.This is because "fasttrap_probe_spec_t" type variable is not fully copied into the > kernel in fasttrap_ioctl() function.I have modified in line with Solaris code where the copying is > done manually by Dtrace, rather than the kernel.(fasttap.c, fasttrap.h) I'm working on this one. > Also in "fasttrap_pid_probe()" (fasttrap_isa.c) for the case of "FASTTRAP_T_PUSHL_EBP", the ebp register > has to be copied to the stack not esp. > I had attached the patch files for review. This has been fixed: http://svnweb.freebsd.org/base?view=revision&revision=257679 http://svnweb.freebsd.org/base?view=revision&revision=257143 > > One other issue i noticed is that if the program being traced uses Thread Local Storage than > for the case of entry probe, it will hang in ___tls_get_addr function in ld-elf.so. > If you use scanf or fscanf in your program you can notice this behaviour. This i believe is due to > Dtrace using gs segment register to point to the scratch space, and TLS also loading the thread variable > from gs register. I haven't been able to reproduce this one yet. If you can send me a program and D script that does the trick, that'd be very helpful. > > if you change the following code in fasttrap_isa.c > <code> > #ifdef __i386__ > addr = USD_GETBASE(&curthread->td_pcb->pcb_gsd); > #else > addr = curthread->td_pcb->pcb_gsbase; > #endif > addr += sizeof (void *); > </code> > > to > > <code> > #ifdef __i386__ > addr = USD_GETBASE(&curthread->td_pcb->pcb_gsd); > #else > addr = curthread->td_pcb->pcb_gsbase; > #endif > addr += sizeof (void *) * 3; > </code> > > the Dtrace will not hang. I am not sure what is happening here and > whether this is the correct solution. Neither am I. :) > This changes were made in FreeBSD 9.2-386-RELEASE. I applied the above patches on > FreeBSD 10-BETA (with some manual work) and it was still working. > _______________________________________________ > freebsd-dtrace@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-dtrace > To unsubscribe, send any mail to "freebsd-dtrace-unsubscribe@freebsd.org"
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