[Bug runtime/18213] New: on arm, the runtime doesn't return correct syscall numbers

[Bug runtime/18213] New: on arm, the runtime doesn't return correct syscall numbers

[dsmith at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18213

            Bug ID: 18213
           Summary: on arm, the runtime doesn't return correct syscall
                    numbers
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: runtime
          Assignee: systemtap at sourceware dot org
          Reporter: dsmith at redhat dot com
              Host: arm

On arm (3.19.3-200.fc21.armv7hl), we're getting a large number of failures in
the syscall/nd_syscall tapset testsuite:

====
# of expected passes            66
# of unexpected failures        200
====

Lots of these are related to dwarfless-probe argument problems, but even in the
dwarf probe case the numbers are much worse than they should be.

After some debugging, I found out that the _stp_syscall_nr() tapset function
always returns 0, which breaks all use of the syscall gate macros (that prevent
syscall nesting). It appears that the kernel version of syscall_get_nr() always
returns 0 on arm.

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[Bug runtime/18213] on arm, the runtime doesn't return correct syscall numbers

[dsmith at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=18213

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #1 from David Smith <dsmith at redhat dot com> ---
Fixed in commit 07cecda.

It appears that the arm kernel's syscall_get_nr() function is designed to only
be used with ftrace syscall tracing. So, on arm, we'll use our own function.

With this patch, the number of syscall/nd_syscall passes almost doubles:

====
# of expected passes            129
# of unexpected failures        137
====

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