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From: "dsmith at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug tapsets/20333] New: merge syscall and nd_syscall tapsets
Date: Wed, 06 Jul 2016 20:38:00 -0000
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X-Bugzilla-Component: tapsets
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X-Bugzilla-Who: dsmith at redhat dot com
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D20333

            Bug ID: 20333
           Summary: merge syscall and nd_syscall tapsets
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: tapsets
          Assignee: systemtap at sourceware dot org
          Reporter: dsmith at redhat dot com
  Target Milestone: ---

It might be possible to merge the syscall and nd_syscall tapsets. Internall=
y,
it might look something like this:

=3D=3D=3D=3D
probe syscall.open =3D kernel.function("sys_open").call !,=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
                     kprobe.function("sys_open") ?=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
{=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20
        name =3D "open"=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
        if (@defined($filename) && @defined($flags) && @defined($mode))=20=
=20=20=20=20=20=20=20=20
        {=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
                filename =3D user_string_quoted(__uint32($filename))=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20
                flags =3D __int32($flags)=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20
                mode =3D __uint32($mode)=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20
        }=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
        else=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
        {=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
                asmlinkage()
                filename =3D user_string_quoted(pointer_arg(1))
                flags =3D int_arg(2)
                mode =3D uint_arg(3)
        }
        if (flags & @const("O_CREAT"))
                argstr =3D sprintf("%s, %s, %#o", filename,
                                 _sys_open_flag_str(flags), mode)
        else
                argstr =3D sprintf("%s, %s", filename,
                                 _sys_open_flag_str(flags))
}

probe nd_syscall.open =3D syscall.open
=3D=3D=3D=3D

Note that the above code really isn't sufficient (or tested). The above code
doesn't handle return probes, compat functions, and syscall nesting.

There are some issues with this idea:

- If you have debuginfo installed, there really isn't a way to specify you =
want
the non-debuginfo version of the probe. (Although why you'd really want to =
do
that I'm not so sure). The above code prefers the debuginfo version.

- Perhaps the biggest problem with this idea is how users actually use sysc=
all
probes. I've seen user code (and I believe some of our examples) use a sysc=
all
probe, but then also use the 'raw' $FOO variables, which certainly wouldn't
work correctly if no debuginfo was installed.

--=20
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