[Bug translator/20307] tapset/linux/rpc.stp error

["dsmith at redhat dot com" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=20307

--- Comment #2 from David Smith <dsmith at redhat dot com> ---
Here's how __rpc_create_args is used (from tapset/linux/rpc.stp):

====
/*                                                                              
 * Newer kernels (> 2.6.18) compiled with gcc less than version                 
 * 4.4.3-16, tend to have debuginfo that doesn't include location               
 * information for inline function arguments.  This is a problem, since         
 * we need the arguments to rpc_new_client(), which is inline.  Since           
 * we can't get them for those kernels, we stash (and delete) the value         
 * of the 'args' parameter of rpc_create().  We then use this value             
 * when probing the inline version of rpc_new_client() (if we don't             
 * have the real arguments to that inline function).                            
 */                                                                             

@__private30 global __rpc_create_args                                           

probe kernel.function("rpc_create").call !,                                     
        module("sunrpc").function("rpc_create").call ?                          
{                                                                               
        __rpc_create_args[tid()] = $args                                        
}                                                                               

probe kernel.function("rpc_create").return !,                                   
        module("sunrpc").function("rpc_create").return ?                        
{                                                                               
        delete __rpc_create_args[tid()]                                         
}                                                                               
====

First, let's see if those entry points exist:

====
# stap -L 'module("sunrpc").function("rpc_create").*'
module("sunrpc").function("rpc_create@net/sunrpc/clnt.c:489").call $args:struct
rpc_create_args* $xprtargs:struct xprt_create $servername:char[]
module("sunrpc").function("rpc_create@net/sunrpc/clnt.c:489").callee("xprt_create_transport@net/sunrpc/xprt.c:1297")
$args:struct xprt_create*
module("sunrpc").function("rpc_create@net/sunrpc/clnt.c:489").exported
$args:struct rpc_create_args* $xprtargs:struct xprt_create $servername:char[]
module("sunrpc").function("rpc_create@net/sunrpc/clnt.c:489").return
$return:struct rpc_clnt* $args:struct rpc_create_args* $xprtargs:struct
xprt_create $servername:char[]
====

So, the module version of those entry points do exist. Now let's see if those
lines are in the pass 1 output:

====
# stap -vp1 ../src/testsuite/buildok/rpc-all-probes.stp | fgrep
__rpc_create_args
%}global __rpc_create_args
(__args) = (__rpc_create_args[tid()]);
(__rpc_create_args[tid()]) = ($args);
delete __rpc_create_args[tid()];
Pass 1: parsed user script and 117 library scripts using
160640virt/43776res/8640shr/30592data kb, in 3230usr/80sys/3347real ms.
====

Yes, the lines are present. So, perhaps the optimizer has optimized the array
away - so let's try things unoptimized:

====
# stap -uvp2 ../src/testsuite/buildok/rpc-all-probes.stp
Pass 1: parsed user script and 117 library scripts using
160576virt/43648res/8576shr/30528data kb, in 2750usr/10sys/2960real ms.
WARNING: cannot probe .return of 1 inlined functions  rpc_release_task
WARNING: cannot probe .return of 1 inlined functions  rpc_release_task
WARNING: cannot probe .return of 1 inlined functions  rpc_release_task
WARNING: cannot probe .return of 1 inlined functions  rpc_release_task
WARNING: cannot probe .return of 1 inlined functions  rpc_release_task
semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at
/usr/local/share/systemtap/tapset/linux/rpc.stp:182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

semantic error: unresolved arity-1 global array __rpc_create_args, missing
global declaration?: identifier '__rpc_create_args' at :182:12
        source:                 __args = __rpc_create_args[tid()]
                                         ^

Pass 2: analyzed script: 158 probes, 880 functions, 9 embeds, 1 global using
272896virt/158016res/10624shr/142848data kb, in 109990usr/2110sys/117436real
ms.
Pass 2: analysis failed.  [man error::pass2]
====

Same exact errors.

More investigation will be needed.

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