[Bug runtime/20042] on rawhide, tracepoint handlers have a changed function signature

[dsmith at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=20042

--- Comment #1 from David Smith <dsmith at redhat dot com> ---
It appears that this isn't a problem with all tracepoints, just certain ones.
The common problem might be that the tracepoints has a function pointer
argument.

In the case of the 'cpuhp_enter' tracepoint, here's what
include/trace/events/cpuhp.h has:

====
...
TRACE_EVENT(cpuhp_enter,

        TP_PROTO(unsigned int cpu,
                 int target,
                 int idx,
                 int (*fun)(unsigned int)),

        TP_ARGS(cpu, target, idx, fun),

        TP_STRUCT__entry(
                __field( unsigned int,  cpu             )
                __field( int,           target          )
                __field( int,           idx             )
                __field( void *,        fun             )
        ),
...
====

The odd thing is here that in TP_PROTO, the function pointer is declared
differently from the same function pointer in TP_STRUCT__entry. Systemtap is
declaring the handler as:

====
static STP_TRACE_ENTER(enter_tracepoint_probe_104
, unsigned int __tracepoint_arg_cpu
, int __tracepoint_arg_target
, int __tracepoint_arg_idx
, void* __tracepoint_arg_fun
)
====

which matches the TP_STRUCT__entry definition, but we might need to switch to
be more like the TP_PROTO definition.

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