Re: [PATCH 2/3] relocate the entry point addess when used

Tom Tromey
2014-01-15T17:59:40Z

>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> I think it's just that the entry point is only really used for the main
Pedro> executable, and if that is loaded at some relocation offset, we'll
Pedro> always go through objfile_relocate (either PIE handling, or RSP
Pedro> qOffsets handling for embedded systems) after reading in symbols,
Pedro> while shared libraries are read in with the offsets already handy
Pedro> upfront.

Yeah, that makes sense.

Pedro> This is assuming osect ends up NULL after iterating over all.
Pedro> It's violating the abstraction of the macro. And, actually,
Pedro> it's wrong, showing exactly why such assumptions are a bad idea:

Tom> Sorry about that, I'll fix it up locally.

Pedro> Thanks.

Here's the updated patch.

Tom

commit 9211b8474f76a95e993f4dc6e2ee873c6997caa4
Author: Tom Tromey <tromey@redhat.com>
Date: Tue Dec 31 06:52:33 2013 -0700

relocate the entry point address when used

This changes the entry point to be unrelocated in the objfile, and
instead applies the relocation when it is used.

2014-01-15 Tom Tromey <tromey@redhat.com>

* objfiles.c (entry_point_address_query): Relocate entry point
address.
(objfile_relocate1): Do not relocate entry point address.
* objfiles.h (struct entry_info) <entry_point>: Update comment.
<the_bfd_section_index>: New field.
* symfile.c (init_entry_point_info): Find the entry point's
section.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 01a4087..5d48363 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,15 @@
2014-01-15 Tom Tromey <tromey@redhat.com>

+ * objfiles.c (entry_point_address_query): Relocate entry point
+ address.
+ (objfile_relocate1): Do not relocate entry point address.
+ * objfiles.h (struct entry_info) <entry_point>: Update comment.
+ <the_bfd_section_index>: New field.
+ * symfile.c (init_entry_point_info): Find the entry point's
+ section.
+
+2014-01-15 Tom Tromey <tromey@redhat.com>
+
* solib-frv.c (enable_break): Use entry_point_address_query.

2014-01-15 Pedro Alves <palves@redhat.com>
diff --git a/gdb/objfiles.c b/gdb/objfiles.c
index 9cc0054..a80d4c7 100644
--- a/gdb/objfiles.c
+++ b/gdb/objfiles.c
@@ -367,7 +367,9 @@ entry_point_address_query (CORE_ADDR *entry_p)
if (symfile_objfile == NULL || !symfile_objfile->ei.entry_point_p)
return 0;

- *entry_p = symfile_objfile->ei.entry_point;
+ *entry_p = (symfile_objfile->ei.entry_point
+ + ANOFFSET (symfile_objfile->section_offsets,
+ symfile_objfile->ei.the_bfd_section_index));

return 1;
}
@@ -794,22 +796,6 @@ objfile_relocate1 (struct objfile *objfile,
to be out of order. */
msymbols_sort (objfile);

- if (objfile->ei.entry_point_p)
- {
- /* Relocate ei.entry_point with its section offset, use SECT_OFF_TEXT
- only as a fallback. */
- struct obj_section *s;
- s = find_pc_section (objfile->ei.entry_point);
- if (s)
- {
- int idx = gdb_bfd_section_index (objfile->obfd, s->the_bfd_section);
-
- objfile->ei.entry_point += ANOFFSET (delta, idx);
- }
- else
- objfile->ei.entry_point += ANOFFSET (delta, SECT_OFF_TEXT (objfile));
- }
-
{
int i;

diff --git a/gdb/objfiles.h b/gdb/objfiles.h
index c2b6177..620d7e8 100644
--- a/gdb/objfiles.h
+++ b/gdb/objfiles.h
@@ -101,9 +101,12 @@ struct objfile_data;

struct entry_info
{
- /* The relocated value we should use for this objfile entry point. */
+ /* The unrelocated value we should use for this objfile entry point. */
CORE_ADDR entry_point;

+ /* The index of the section in which the entry point appears. */
+ int the_bfd_section_index;
+
/* Set to 1 iff ENTRY_POINT contains a valid value. */
unsigned entry_point_p : 1;
};
diff --git a/gdb/symfile.c b/gdb/symfile.c
index d863282..bd12552 100644
--- a/gdb/symfile.c
+++ b/gdb/symfile.c
@@ -894,7 +894,9 @@ init_entry_point_info (struct objfile *objfile)

if (objfile->ei.entry_point_p)
{
+ struct obj_section *osect;
CORE_ADDR entry_point = objfile->ei.entry_point;
+ int found;

/* Make certain that the address points at real code, and not a
function descriptor. */
@@ -907,6 +909,25 @@ init_entry_point_info (struct objfile *objfile)
symbol table. */
objfile->ei.entry_point
= gdbarch_addr_bits_remove (get_objfile_arch (objfile), entry_point);
+
+ found = 0;
+ ALL_OBJFILE_OSECTIONS (objfile, osect)
+ {
+ struct bfd_section *sect = osect->the_bfd_section;
+
+ if (entry_point >= bfd_get_section_vma (objfile->obfd, sect)
+ && entry_point < (bfd_get_section_vma (objfile->obfd, sect)
+ + bfd_get_section_size (sect)))
+ {
+ objfile->ei.the_bfd_section_index
+ = gdb_bfd_section_index (objfile->obfd, sect);
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found)
+ objfile->ei.the_bfd_section_index = SECT_OFF_TEXT (objfile);
}
}