Re: [PATCH v4 1/3] systemtap/tapsets.cxx: Fix dwarfless probes on multiple static functions

[Mark Wielaard <mjw at redhat dot com>]

Hi Hemant,

On Mon, 2015-04-20 at 15:59 +0530, Hemant Kumar wrote:
> With multiple static functions with same names in an ELF and in absence
> of dwarf, if we probe on one of the functions, then systemtap places
> probe only on one static function ignoring the rest. This is because the
> mapping between the symbol names and their func_info is a simple map
> which doesn't allow insertion of another symbol with the same name.
> 
> This patch fixes this issue by changing this map to a multimap which
> allows duplicate entries for the same symbol name. lookup_symbol code
> will return a set of func_info * instead of a single descriptor for a
> function name.
> 
> We also need to fix other areas in the code where lookup_symbol() and
> lookup_symbol_address() are being called so as to look for a set of
> func_info's and a list of Dwarf_Addr's respectively, instead of a single
> descriptor.

Looks good. I pushed this with one tiny change:

@@ -8242,6 +8242,8 @@ symbol_table::purge_syscall_stubs()
   if (!addrs || addrs->empty())
     return;
   /* Highly unlikely that multiple symbols named "sys_ni_syscall" may exist */
+  if (addrs->size() > 1)
+    cerr << _("Multiple 'sys_ni_syscall' symbols found.");
   Dwarf_Addr stub_addr = addrs->front();

Just so that if this highly unlikely scenario does occur we get a
warning something is fishy.

Thanks,

Mark