Re: [patch] Fixes problem setting breakpoint in dynamic loader

[PAUL GILLIAM <pgilliam at us dot ibm dot com>]

It's been just about a month, so I thought I try again (and use the new
patch tracker!)

:ADDPATCH PowerPC-64:

> On Thu, 2006-05-25 at 18:58 -0400, Daniel Jacobowitz wrote:

> > 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 have attached the patches again.  'loader_break.diff' applied cleanly
to cvs-head, but I had to do a trivial tweak to 'rs6000.diff' so that it
would.

OK to commit?

-=# Paul #=-


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);

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

        *rs6000-tdep.c (rs6000_convert_from_func_ptr_addr): Use target_ops.

Index: rs6000-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/rs6000-tdep.c,v
retrieving revision 1.258
diff -a -u -r1.258 rs6000-tdep.c
--- rs6000-tdep.c	23 Apr 2006 14:15:01 -0000	1.258
+++ rs6000-tdep.c	23 Jun 2006 21:22:32 -0000
@@ -2338,7 +2338,8 @@
    inferior's memory space, with all its drawbacks.  To be able to
    call C++ virtual methods in the inferior (which are called via
    function pointers), find_function_addr uses this function to get the
-   function address from a function pointer.  */
+   function address from a function pointer.  It is also used by
+   enable_break from svr4_solib_create_inferior_hook.  */
 
 /* Return real function address if ADDR (a function pointer) is in the data
    space and is therefore a special function pointer.  */
@@ -2355,7 +2356,9 @@
     return addr;
 
   /* ADDR is in the data space, so it's a special function pointer. */
-  return read_memory_addr (addr, gdbarch_tdep (current_gdbarch)->wordsize);
+
+  return get_target_memory_unsigned (targ, addr,
+                                     gdbarch_tdep (current_gdbarch)->wordsize);
 }