[RFC] Make solib-frv.c work in a non-FDPIC environment

[RFC] Make solib-frv.c work in a non-FDPIC environment

[Kevin Buettner]

This patch allows solib-frv.c to be used in a non-FDPIC environment. 
Such an environment is found when testing a FDPIC multilib using the
FRV simulator.  In such an environment, both the interpreter and
loadmap addresses will be zero.

Comments?

	* solib-frv.c (fetch_loadmap): Return early when no segments are
	found.
	(frv_relocate_main_executable): Return early when both interpreter
	and executable loadmap addresses are zero.

Index: solib-frv.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-frv.c,v
retrieving revision 1.22
diff -u -p -r1.22 solib-frv.c
--- solib-frv.c	26 Aug 2008 17:30:35 -0000	1.22
+++ solib-frv.c	14 Nov 2008 22:40:25 -0000
@@ -124,6 +124,9 @@ fetch_loadmap (CORE_ADDR ldmaddr)
   nsegs = extract_unsigned_integer (ext_ldmbuf_partial.nsegs,
                                     sizeof ext_ldmbuf_partial.nsegs);
 
+  if (nsegs < 0)
+    return NULL;
+
   /* Allocate space for the complete (external) loadmap.  */
   ext_ldmbuf_size = sizeof (struct ext_elf32_fdpic_loadmap)
                + (nsegs - 1) * sizeof (struct ext_elf32_fdpic_loadseg);
@@ -860,16 +863,17 @@ static void
 frv_relocate_main_executable (void)
 {
   int status;
-  CORE_ADDR exec_addr;
+  CORE_ADDR exec_addr, interp_addr;
   struct int_elf32_fdpic_loadmap *ldm;
   struct cleanup *old_chain;
   struct section_offsets *new_offsets;
   int changed;
   struct obj_section *osect;
 
-  status = frv_fdpic_loadmap_addresses (target_gdbarch, 0, &exec_addr);
+  status = frv_fdpic_loadmap_addresses (target_gdbarch,
+                                        &interp_addr, &exec_addr);
 
-  if (status < 0)
+  if (status < 0 || (exec_addr == 0 && interp_addr == 0))
     {
       /* Not using FDPIC ABI, so do nothing.  */
       return;

Re: [RFC] Make solib-frv.c work in a non-FDPIC environment

[Daniel Jacobowitz]

On Fri, Nov 14, 2008 at 04:21:03PM -0700, Kevin Buettner wrote:
> +  if (nsegs < 0)
> +    return NULL;
> +
>    /* Allocate space for the complete (external) loadmap.  */
>    ext_ldmbuf_size = sizeof (struct ext_elf32_fdpic_loadmap)
>                 + (nsegs - 1) * sizeof (struct ext_elf32_fdpic_loadseg);

<= 0?  I realize it's probably OK in practice, assuming
ext_elf32_fdpic_loadmap has a trailing [1] array, but allocating less
than the size of the array would be strange.

Otherwise sounds good.

-- 
Daniel Jacobowitz
CodeSourcery

Re: [RFC] Make solib-frv.c work in a non-FDPIC environment

[Kevin Buettner]

On Sat, 15 Nov 2008 11:14:43 -0500
Daniel Jacobowitz <drow@false.org> wrote:

> On Fri, Nov 14, 2008 at 04:21:03PM -0700, Kevin Buettner wrote:
> > +  if (nsegs < 0)
> > +    return NULL;
> > +
> >    /* Allocate space for the complete (external) loadmap.  */
> >    ext_ldmbuf_size = sizeof (struct ext_elf32_fdpic_loadmap)
> >                 + (nsegs - 1) * sizeof (struct ext_elf32_fdpic_loadseg);
> 
> <= 0?  I realize it's probably OK in practice, assuming
> ext_elf32_fdpic_loadmap has a trailing [1] array, but allocating less
> than the size of the array would be strange.

I agree.

Here's the version that I committed:

	* solib-frv.c (fetch_loadmap): Return early when no segments are
	found.
	(frv_relocate_main_executable): Return early when both interpreter
	and executable loadmap addresses are zero.

Index: solib-frv.c
===================================================================
RCS file: /cvs/src/src/gdb/solib-frv.c,v
retrieving revision 1.22
diff -u -p -r1.22 solib-frv.c
--- solib-frv.c	26 Aug 2008 17:30:35 -0000	1.22
+++ solib-frv.c	19 Nov 2008 21:15:17 -0000
@@ -124,6 +124,9 @@ fetch_loadmap (CORE_ADDR ldmaddr)
   nsegs = extract_unsigned_integer (ext_ldmbuf_partial.nsegs,
                                     sizeof ext_ldmbuf_partial.nsegs);
 
+  if (nsegs <= 0)
+    return NULL;
+
   /* Allocate space for the complete (external) loadmap.  */
   ext_ldmbuf_size = sizeof (struct ext_elf32_fdpic_loadmap)
                + (nsegs - 1) * sizeof (struct ext_elf32_fdpic_loadseg);
@@ -860,16 +863,17 @@ static void
 frv_relocate_main_executable (void)
 {
   int status;
-  CORE_ADDR exec_addr;
+  CORE_ADDR exec_addr, interp_addr;
   struct int_elf32_fdpic_loadmap *ldm;
   struct cleanup *old_chain;
   struct section_offsets *new_offsets;
   int changed;
   struct obj_section *osect;
 
-  status = frv_fdpic_loadmap_addresses (target_gdbarch, 0, &exec_addr);
+  status = frv_fdpic_loadmap_addresses (target_gdbarch,
+                                        &interp_addr, &exec_addr);
 
-  if (status < 0)
+  if (status < 0 || (exec_addr == 0 && interp_addr == 0))
     {
       /* Not using FDPIC ABI, so do nothing.  */
       return;