[Bug testsuite/15625] New: unprivileged_embedded_C test confused by stub registers.stp

[Bug testsuite/15625] New: unprivileged_embedded_C test confused by stub registers.stp

[jkenisto at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

            Bug ID: 15625
           Summary: unprivileged_embedded_C test confused by stub
                    registers.stp
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: testsuite
          Assignee: systemtap at sourceware dot org
          Reporter: jkenisto at us dot ibm.com

When running the systemtap.unprivileged/unprivileged_embedded_C.exp test, I see
the following failure:
...
testing s64_arg (long);no embedded C
testing u64_arg (long);no embedded C
testing asmlinkage();no embedded C
testing fastcall();no embedded C
testing regparm(long);no embedded C
eval exec stap -p2 --privilege=stapusr -e {probe begin { regparm(0) }}
semantic error: function may not be used when --privilege=stapusr is specified:
identifier 'regparm' at /usr/share/systemtap/tapset/i386/registers.stp:245:10
        source: function regparm(n:long) %{
                         ^

Pass 2: analysis failed.  Try again with another '--vp 01' option.
funcname is regparm
FAIL: unprivileged embedded C: no embedded C: --privilege=stapusr:
regparm(long)

stap correctly detects that regparm() in tapset/i386/registers.stp uses
embedded C,** but the test is looking at tapset/registers.stp, which contains
only stub functions with no embedded C.

A fix is to have the test ignore the stub registers.stp.

**Should the functions in registers.stp be marked unprivileged?  They provide
read-only access to CPU registers and function args.

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[Bug testsuite/15625] unprivileged_embedded_C test confused by stub registers.stp

[jkenisto at us dot ibm.com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

--- Comment #1 from Jim Keniston <jkenisto at us dot ibm.com> ---
Created attachment 7078
  --> http://sourceware.org/bugzilla/attachment.cgi?id=7078&action=edit
Make embeddedc.awk skip over stub registers.stp

This patch seems to do the trick.

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[Bug testsuite/15625] unprivileged_embedded_C test confused by stub registers.stp

[jistone at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

Josh Stone <jistone at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jistone at redhat dot com

--- Comment #2 from Josh Stone <jistone at redhat dot com> ---
(In reply to Jim Keniston from comment #0)
> **Should the functions in registers.stp be marked unprivileged?  They
> provide read-only access to CPU registers and function args.

Unprivileged functions shouldn't leak kernel info though, so these functions
would need to restrict themselves to CONTEXT->uregs in this mode, and only for
one's own processes.

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[Bug testsuite/15625] unprivileged_embedded_C test confused by stub registers.stp

[fche at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

Frank Ch. Eigler <fche at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fche at redhat dot com

--- Comment #3 from Frank Ch. Eigler <fche at redhat dot com> ---
Considering that unprivileged mode probes do not include kprobes or similar
kernel-internal facilities, it may be sufficient to mark these register.stp
tapset functions /* myproc-unprivileged */ (to check process ownership).

As a belt-and-suspenders kind of thing, _stp_arg() could get a
STP_PRIVILEGE-level test to permit access to CONTEXT->regs (the
non-user-space one) only to stapsys/stapdev users.

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[Bug testsuite/15625] unprivileged_embedded_C test confused by stub registers.stp

[brolley at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

Dave Brolley <brolley at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|systemtap at sourceware dot org    |brolley at redhat dot com

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[Bug testsuite/15625] unprivileged_embedded_C test confused by stub registers.stp

[brolley at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=15625

Dave Brolley <brolley at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |brolley at redhat dot com

--- Comment #4 from Dave Brolley <brolley at redhat dot com> ---
(In reply to Jim Keniston from comment #1)
> Created attachment 7078 [details]
> Make embeddedc.awk skip over stub registers.stp
> 
> This patch seems to do the trick.

The proper and more general solution for this is to fix embeddedc.awk so that
it does not analyse stub functions. Skipping entire files is too granular.

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