Test for 32/64 bit object file?
Richard Henderson
rth@cygnus.com
Tue Nov 16 18:35:00 GMT 1999
On Wed, Nov 17, 1999 at 09:00:02AM +1100, Andrew Cagney wrote:
> GDB encounters situtations (c.f. assorted mips targets) where the object
> file contains 32 bit addresses but the target has a 64 bit address
> space. The 32 address values being implicitly zero or sign extended to
> 64 bits. GDB needs to know what the object file format assumed (or
> didn't in some case) is doing so that it can correctly do things like
> compares.
I was thinking something like this might work. The idea is to
have bfd_vma be 64-bits (which it already is), and have the BFD
sign extend the values it finds in the elf32 object files. This
mirrors what we do for e.g. R_MIPS_64 in such a case, and thus
what a run-time loader ought to be doing as well.
GDB should continue to use complete 64-bit addresses, since the
entire address space is potentially valid at runtime.
Comments?
r~
* elf-bfd.h (struct elf_backend_data): Reorder collect and
type_change_ok; add sign_extend_vma.
* elf32-mips.c (elf_backend_sign_extend_vma): Define.
* elfcode.h (elf_swap_symbol_in): Mind be->sign_extend_vma.
(elf_swap_shdr_in, elf_swap_phdr_in): Likewise.
* elfxx-target.h (elf_backend_sign_extend_vma): Default.
(elfNN_bed): Follow struture changes.
Index: elf-bfd.h
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elf-bfd.h,v
retrieving revision 1.55
diff -c -p -d -r1.55 elf-bfd.h
*** elf-bfd.h 1999/09/14 01:13:01 1.55
--- elf-bfd.h 1999/11/17 02:26:58
*************** struct elf_backend_data
*** 329,346 ****
/* The maximum page size for this backend. */
bfd_vma maxpagesize;
- /* This is true if the linker should act like collect and gather
- global constructors and destructors by name. This is true for
- MIPS ELF because the Irix 5 tools can not handle the .init
- section. */
- boolean collect;
-
- /* This is true if the linker should ignore changes to the type of a
- symbol. This is true for MIPS ELF because some Irix 5 objects
- record undefined functions as STT_OBJECT although the definitions
- are STT_FUNC. */
- boolean type_change_ok;
-
/* A function to translate an ELF RELA relocation to a BFD arelent
structure. */
void (*elf_info_to_howto) PARAMS ((bfd *, arelent *,
--- 329,334 ----
*************** struct elf_backend_data
*** 600,605 ****
--- 588,605 ----
bfd_vma got_header_size;
bfd_vma plt_header_size;
+ /* This is true if the linker should act like collect and gather
+ global constructors and destructors by name. This is true for
+ MIPS ELF because the Irix 5 tools can not handle the .init
+ section. */
+ unsigned collect : 1;
+
+ /* This is true if the linker should ignore changes to the type of a
+ symbol. This is true for MIPS ELF because some Irix 5 objects
+ record undefined functions as STT_OBJECT although the definitions
+ are STT_FUNC. */
+ unsigned type_change_ok : 1;
+
/* Whether the backend may use REL relocations. (Some backends use
both REL and RELA relocations, and this flag is set for those
backends.) */
*************** struct elf_backend_data
*** 616,621 ****
--- 616,625 ----
and the backend wants RELA relocations for a particular
section. */
unsigned default_use_rela_p : 1;
+
+ /* True if addresses "naturally" sign extend. This is used when
+ swapping in from Elf32 when BFD64. */
+ unsigned sign_extend_vma : 1;
unsigned want_got_plt : 1;
unsigned plt_readonly : 1;
Index: elf32-mips.c
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elf32-mips.c,v
retrieving revision 1.165
diff -c -p -d -r1.165 elf32-mips.c
*** elf32-mips.c 1999/10/22 15:51:39 1.165
--- elf32-mips.c 1999/11/17 02:26:58
*************** static const struct ecoff_debug_swap mip
*** 9114,9119 ****
--- 9114,9120 ----
#define elf_backend_collect true
#define elf_backend_type_change_ok true
#define elf_backend_can_gc_sections true
+ #define elf_backend_sign_extend_vma true
#define elf_info_to_howto mips_info_to_howto_rela
#define elf_info_to_howto_rel mips_info_to_howto_rel
#define elf_backend_sym_is_global mips_elf_sym_is_global
Index: elfcode.h
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elfcode.h,v
retrieving revision 1.239
diff -c -p -d -r1.239 elfcode.h
*** elfcode.h 1999/09/14 01:16:13 1.239
--- elfcode.h 1999/11/17 02:26:58
*************** elf_swap_symbol_in (abfd, src, dst)
*** 205,212 ****
const Elf_External_Sym *src;
Elf_Internal_Sym *dst;
{
dst->st_name = bfd_h_get_32 (abfd, (bfd_byte *) src->st_name);
! dst->st_value = get_word (abfd, (bfd_byte *) src->st_value);
dst->st_size = get_word (abfd, (bfd_byte *) src->st_size);
dst->st_info = bfd_h_get_8 (abfd, (bfd_byte *) src->st_info);
dst->st_other = bfd_h_get_8 (abfd, (bfd_byte *) src->st_other);
--- 205,217 ----
const Elf_External_Sym *src;
Elf_Internal_Sym *dst;
{
+ int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
+
dst->st_name = bfd_h_get_32 (abfd, (bfd_byte *) src->st_name);
! if (signed_vma)
! dst->st_value = get_signed_word (abfd, (bfd_byte *) src->st_value);
! else
! dst->st_value = get_word (abfd, (bfd_byte *) src->st_value);
dst->st_size = get_word (abfd, (bfd_byte *) src->st_size);
dst->st_info = bfd_h_get_8 (abfd, (bfd_byte *) src->st_info);
dst->st_other = bfd_h_get_8 (abfd, (bfd_byte *) src->st_other);
*************** elf_swap_shdr_in (abfd, src, dst)
*** 293,302 ****
const Elf_External_Shdr *src;
Elf_Internal_Shdr *dst;
{
dst->sh_name = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_name);
dst->sh_type = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_type);
dst->sh_flags = get_word (abfd, (bfd_byte *) src->sh_flags);
! dst->sh_addr = get_word (abfd, (bfd_byte *) src->sh_addr);
dst->sh_offset = get_word (abfd, (bfd_byte *) src->sh_offset);
dst->sh_size = get_word (abfd, (bfd_byte *) src->sh_size);
dst->sh_link = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_link);
--- 298,312 ----
const Elf_External_Shdr *src;
Elf_Internal_Shdr *dst;
{
+ int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
+
dst->sh_name = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_name);
dst->sh_type = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_type);
dst->sh_flags = get_word (abfd, (bfd_byte *) src->sh_flags);
! if (signed_vma)
! dst->sh_addr = get_signed_word (abfd, (bfd_byte *) src->sh_addr);
! else
! dst->sh_addr = get_word (abfd, (bfd_byte *) src->sh_addr);
dst->sh_offset = get_word (abfd, (bfd_byte *) src->sh_offset);
dst->sh_size = get_word (abfd, (bfd_byte *) src->sh_size);
dst->sh_link = bfd_h_get_32 (abfd, (bfd_byte *) src->sh_link);
*************** elf_swap_phdr_in (abfd, src, dst)
*** 339,349 ****
const Elf_External_Phdr *src;
Elf_Internal_Phdr *dst;
{
dst->p_type = bfd_h_get_32 (abfd, (bfd_byte *) src->p_type);
dst->p_flags = bfd_h_get_32 (abfd, (bfd_byte *) src->p_flags);
dst->p_offset = get_word (abfd, (bfd_byte *) src->p_offset);
! dst->p_vaddr = get_word (abfd, (bfd_byte *) src->p_vaddr);
! dst->p_paddr = get_word (abfd, (bfd_byte *) src->p_paddr);
dst->p_filesz = get_word (abfd, (bfd_byte *) src->p_filesz);
dst->p_memsz = get_word (abfd, (bfd_byte *) src->p_memsz);
dst->p_align = get_word (abfd, (bfd_byte *) src->p_align);
--- 349,369 ----
const Elf_External_Phdr *src;
Elf_Internal_Phdr *dst;
{
+ int signed_vma = get_elf_backend_data (abfd)->sign_extend_vma;
+
dst->p_type = bfd_h_get_32 (abfd, (bfd_byte *) src->p_type);
dst->p_flags = bfd_h_get_32 (abfd, (bfd_byte *) src->p_flags);
dst->p_offset = get_word (abfd, (bfd_byte *) src->p_offset);
! if (signed_vma)
! {
! dst->p_vaddr = get_signed_word (abfd, (bfd_byte *) src->p_vaddr);
! dst->p_paddr = get_signed_word (abfd, (bfd_byte *) src->p_paddr);
! }
! else
! {
! dst->p_vaddr = get_word (abfd, (bfd_byte *) src->p_vaddr);
! dst->p_paddr = get_word (abfd, (bfd_byte *) src->p_paddr);
! }
dst->p_filesz = get_word (abfd, (bfd_byte *) src->p_filesz);
dst->p_memsz = get_word (abfd, (bfd_byte *) src->p_memsz);
dst->p_align = get_word (abfd, (bfd_byte *) src->p_align);
Index: elfxx-target.h
===================================================================
RCS file: /cvs/cvsfiles/devo/bfd/elfxx-target.h,v
retrieving revision 1.42
diff -c -p -d -r1.42 elfxx-target.h
*** elfxx-target.h 1999/07/19 07:54:12 1.42
--- elfxx-target.h 1999/11/17 02:26:59
*************** Foundation, Inc., 59 Temple Place - Suit
*** 332,337 ****
--- 332,341 ----
#define elf_backend_size_info _bfd_elfNN_size_info
#endif
+ #ifndef elf_backend_sign_extend_vma
+ #define elf_backend_sign_extend_vma 0
+ #endif
+
extern const struct elf_size_info _bfd_elfNN_size_info;
static CONST struct elf_backend_data elfNN_bed =
*************** static CONST struct elf_backend_data elf
*** 339,346 ****
ELF_ARCH, /* arch */
ELF_MACHINE_CODE, /* elf_machine_code */
ELF_MAXPAGESIZE, /* maxpagesize */
- elf_backend_collect,
- elf_backend_type_change_ok,
elf_info_to_howto,
elf_info_to_howto_rel,
elf_backend_sym_is_global,
--- 343,348 ----
*************** static CONST struct elf_backend_data elf
*** 376,384 ****
--- 378,389 ----
elf_backend_got_symbol_offset,
elf_backend_got_header_size,
elf_backend_plt_header_size,
+ elf_backend_collect,
+ elf_backend_type_change_ok,
elf_backend_may_use_rel_p,
elf_backend_may_use_rela_p,
elf_backend_default_use_rela_p,
+ elf_backend_sign_extend_vma,
elf_backend_want_got_plt,
elf_backend_plt_readonly,
elf_backend_want_plt_sym,
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