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Subject: Re: [patch] Fixes problem setting breakpoint in dynamic loader
From: PAUL GILLIAM <pgilliam@us.ibm.com>
Reply-To: pgilliam@us.ibm.com
To: Daniel Jacobowitz <drow@false.org>
Cc: gdb-patches@sources.redhat.com
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Boy! That was fast!  Thanks!

On Thu, 2006-05-25 at 18:58 -0400, Daniel Jacobowitz wrote:
> On Thu, May 25, 2006 at 02:52:50PM -0700, PAUL GILLIAM wrote:
> > 2006-05-25  Paul Gilliam  <pgilliam@us.ibm.com
> > 
> > 	* solib-svr4.c (enable_break): Resolve break address when the
> > 	symbol is found in the data section.
> 
> Need a changelog for the removal of "._dl_debug_state", too.
> 
OK.

> I don't feel that I can really review this; I'm going to wait a while
> and hope someone more familiar with a function descriptor platform
> responds.
> 
I suppose that goes for the rs6000-tdep.c patch as well.

-=# Paul #=-

PS: Any chance of getting these into 6.5?

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2006-05-25  Paul Gilliam  <pgilliam@us.ibm.com

	* solib-svr4.c: Remove "._dl_debug_state" from the list of symbols at
	which to try setting a breakpoint for tracking solibs.
	(enable_break): Resolve break address when the symbol is found in
	the data section.

Index: solib-svr4.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-svr4.c,v
retrieving revision 1.58
diff -a -u -r1.58 solib-svr4.c
--- solib-svr4.c	18 May 2006 20:38:56 -0000	1.58
+++ solib-svr4.c	25 May 2006 22:12:55 -0000
@@ -85,16 +85,6 @@
   "rtld_db_dlactivity",
   "_rtld_debug_state",
 
-  /* On the 64-bit PowerPC, the linker symbol with the same name as
-     the C function points to a function descriptor, not to the entry
-     point.  The linker symbol whose name is the C function name
-     prefixed with a '.' points to the function's entry point.  So
-     when we look through this table, we ignore symbols that point
-     into the data section (thus skipping the descriptor's symbol),
-     and eventually try this one, giving us the real entry point
-     address.  */
-  "._dl_debug_state",
-
   NULL
 };
 
@@ -1043,20 +1033,45 @@
       /* Now try to set a breakpoint in the dynamic linker.  */
       for (bkpt_namep = solib_break_names; *bkpt_namep != NULL; bkpt_namep++)
 	{
-          /* On ABI's that use function descriptors, there are usually
-             two linker symbols associated with each C function: one
-             pointing at the actual entry point of the machine code,
-             and one pointing at the function's descriptor.  The
-             latter symbol has the same name as the C function.
-
-             What we're looking for here is the machine code entry
-             point, so we are only interested in symbols in code
-             sections.  */
+	  /* What we're looking for here is the machine code entry point,
+	     so we are only interested in symbols in code sections.
+
+	     On ABI's that use function descriptors, the linker symbol with
+	     the same name as a C funtion points to that functions descriptor.
+	     when those function descriptors are in the code section, they
+	     contain executable code and we can set a breakpoint there. */
 	  sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep, SEC_CODE);
 	  if (sym_addr != 0)
 	    break;
 	}
 
+      if (sym_addr == 0)
+        {
+	  CORE_ADDR sect_offset;
+	  
+	  /* No symbol was found in a code section, so look in the data
+             sections.  This will only happen when the linker symbol points
+	     to a function descriptor that is in a data section. */
+	  for (bkpt_namep = solib_break_names; *bkpt_namep!=NULL; bkpt_namep++)
+	    {
+	      /* On ABI's that use function descriptors that are in the data
+	         section, */
+	      sym_addr = bfd_lookup_symbol (tmp_bfd, *bkpt_namep, SEC_DATA);
+	      if (sym_addr != 0)
+		break;
+	    }
+	  if (sym_addr == 0)
+	    {
+	      target_close (tmp_bfd_target, 0);
+	      goto bkpt_at_symbol;
+	    }
+
+	  /* Convert 'sym_addr' from a function pointer to an address. */
+	  sym_addr = gdbarch_convert_from_func_ptr_addr (current_gdbarch,
+							 sym_addr,
+							 tmp_bfd_target);
+        }
+
       /* We're done with both the temporary bfd and target.  Remember,
          closing the target closes the underlying bfd.  */
       target_close (tmp_bfd_target, 0);

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