uaddr and friends

[carlos antonio neira bustos]

Thanks Mark.

You are right, I did not look at dt_subr.c, uaddr is a short version of
ustack, I'll update to current now and try to pick on something else from
the list.

Bests


On Tue, Apr 15, 2014 at 11:36 PM, Mark Johnston <markj at freebsd.org> wrote:

> On Tue, Apr 15, 2014 at 10:15 PM, carlos antonio neira bustos
> <cneirabustos at gmail.com> wrote:
> > Hi Mark,
> >
> > I was looking at this document
> >
> https://wikis.oracle.com/display/DTrace/Actions+and+Subroutines#ActionsandSubroutines-%7B%7Busym%7D%7D
> > currently looking at the code uaddr is the same as usym, but according to
> > this document
> >
> > usym will print the symbol for a specified address. This is analogous to
> how
> > uaddr works, but without the hexadecimal offsets.
> >
> >         uaddr:          date`clock_val+0x1
> >         usym:           date`clock_val
> >
> >
> > here are my outputs from usym and uaddr :
> >
> > root at bsd:/home/cneira # dtrace -n
> 'pid$target::main:{usym(uregs[R_PC])}' -c
> > ./test
> > dtrace: description 'pid$target::main:' matched 2 probes
> > abCPU     ID                    FUNCTION:NAME
> >   0  56282                       main:entry   test`main
> >   0  56281                      main:return   test`main
> > dtrace: pid 10588 has exited
> >
> > root at bsd:/home/cneira # dtrace -n
> 'pid$target::main:{uaddr(uregs[R_PC])}' -c
> > ./test
> > dtrace: description 'pid$target::main:' matched 2 probes
> > abCPU     ID                    FUNCTION:NAME
> >   0  56282                       main:entry
> >               test`main+0x1
> >
> >   0  56281                      main:return
> >               test`main+0x23
> >
> > dtrace: pid 10591 has exited
> >
> > As current is only using dt_print_usym for uaddr the output should not
> have
> > the  hexadecimal offset specified in that documentation.
> > So I'm somewhat lost about which is the correct behavior , Do you have a
> > uaddr and usym  output  example in current to check this?, all my changes
> > were done in 10 prod release.
>
> You're right, dt_print_usym handles both usym and uaddr. In the usym
> case, there's some special handling which looks up the symbol name
> corresponding to the given pc, and then sets the pc variable to the
> address of the symbol. Then dtrace_uaddr2str only prints the offset
> from the symbol if that offset is non-zero, so in the uaddr case you
> get "+0x1" and "+0x23" above.
>
> >
> > Bests
> >
> >
> >
> >
> >
> >
> >
> > On Tue, Apr 15, 2014 at 10:09 PM, Mark Johnston <markj at freebsd.org>
> wrote:
> >>
> >> On Tue, Apr 15, 2014 at 8:35 PM, carlos antonio neira bustos
> >> <cneirabustos at gmail.com> wrote:
> >> > Hi All,
> >> >
> >> > I was looking at Dtrace todo list from
> >> > https://wiki.freebsd.org/DTraceTODO
> >> > and started to work on : Get uaddr(), ufunc(), umod(), and usym()
> action
> >> > funtions working.
> >> > I have  the  data recording action (uaddr)  working  now, here is an
> >> > example:
> >>
> >> Hi!
> >>
> >> Hm, these should have been (at least mostly) working since r258902:
> >> http://svnweb.freebsd.org/base?view=revision&revision=258902
> >>
> >> >
> >> > root at bsd:/home/cneira # dtrace -n
> >> > 'pid$target::main:{uaddr(uregs[R_PC])}'
> >> > -c ./test
> >> > dtrace: description 'pid$target::main:' matched 2 probes
> >> > abCPU     ID                    FUNCTION:NAME
> >> >   0  56282                       main:entry
> >> >               test`main+0x1
> >> >
> >> >   0  56281                      main:return
> >> >               test`main+0x23
> >> >
> >> > dtrace: pid 9687 has exited
> >> >
> >> > Here is the output of nm from the test binary I have used to check
> this
> >> > change.
> >> >
> >> >         U _init_tls@@FBSD_1.0
> >> > 08048380 T _start
> >> > 080483a0 t _start1
> >> > 0804814c r abitag
> >> >          U atexit@@FBSD_1.0
> >> > 08048164 r crt_noinit_tag
> >> > 080485c0 T dosomething
> >> > 08049764 B environ
> >> >          U exit@@FBSD_1.0
> >> > 080484f0 t finalizer
> >> > 08048560 t frame_dummy
> >> > 08048590 T main
> >> >          U putchar@@FBSD_1.0
> >> >
> >> >
> >> > root at bsd:/home/cneira # dtrace -c ./test -n 'pid$target::main:entry{
> >> > uaddr(0x080485c0); }'
> >> > dtrace: description 'pid$target::main:entry' matched 1 probe
> >> > abCPU     ID                    FUNCTION:NAME
> >> >   0  56281                       main:entry
> >> >               test`dosomething
> >> >
> >> > dtrace: pid 9736 has exited
> >> >
> >> > I'll continue working on the rest, how do I submit  a patch with these
> >> > changes ?
> >>
> >> Pasting it inline is generally fine if it's not too large. It's also
> >> ok to put it in a public directory somewhere and post a link to it.
> >>
> >> -Mark
> >
> >
>