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Re: RFC: Mark discarded debug info more thoroughly
On Thu, Oct 26, 2006 at 11:54:06AM -0400, Daniel Jacobowitz wrote:
> Here is a version of the patch which adjusts all ELF targets that I
> could readily find the right place to change (a couple done by hand,
> plus searches for r_symndx == 0). I've built it with
> --enable-targets=all, and tested a few of the changed targets, but not
> all.
>
> There's also a testcase. I expect that it is going to fail on a bunch
> of more obscure targets that I haven't tested. Should I build and test
> all ELF targets? If so, does anyone have a current list of target
> tuples to test, and if so, should it be in CVS somewhere?
Questions stand; here's a revised version that also fixes SH.
--
Daniel Jacobowitz
CodeSourcery
2006-10-26 Daniel Jacobowitz <dan@codesourcery.com>
* libbfd-in.h (_bfd_clear_contents): New prototype.
* reloc.c (_bfd_clear_contents): New.
* libbfd.h: Regenerated.
* elf32-arm.c (elf32_arm_final_link_relocate): Use
_bfd_clear_contents.
* elf32-hppa.c (elf32_hppa_relocate_section): Likewise.
* elf32-i386.c (elf_i386_relocate_section): Likewise.
* elf32-ppc.c (ppc_elf_relocate_section): Likewise.
* elf32-s390.c (elf_s390_relocate_section): Likewise.
* elf32-sh.c (sh_elf_relocate_section): Likewise.
* elf64-ppc.c (ppc64_elf_relocate_section): Likewise.
* elf64-s390.c (elf_s390_relocate_section): Likewise.
* elf64-x86-64.c (elf64_x86_64_relocate_section): Likewise.
* elfxx-sparc.c (_bfd_sparc_elf_relocate_section): Likewise.
* elfxx-ia64.c (elfNN_ia64_relocate_section): Set value to
zero for discarded symbols.
* elfxx-mips.c (mips_elf_calculate_relocation): Likewise.
2006-10-26 Daniel Jacobowitz <dan@codesourcery.com>
* ld-discard/zero-rel.d, ld-discard/zero-rel.s: New files.
Index: bfd/elf32-arm.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-arm.c,v
retrieving revision 1.97
diff -u -p -r1.97 elf32-arm.c
--- bfd/elf32-arm.c 19 Oct 2006 02:10:41 -0000 1.97
+++ bfd/elf32-arm.c 26 Oct 2006 15:39:50 -0000
@@ -3654,7 +3654,10 @@ elf32_arm_final_link_relocate (reloc_how
from removed linkonce sections, or sections discarded by
a linker script. */
if (r_symndx == 0)
- return bfd_reloc_ok;
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ return bfd_reloc_ok;
+ }
/* Handle relocations which should use the PLT entry. ABS32/REL32
will use the symbol's value, which may point to a PLT entry, but we
Index: bfd/elf32-hppa.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-hppa.c,v
retrieving revision 1.148
diff -u -p -r1.148 elf32-hppa.c
--- bfd/elf32-hppa.c 17 Oct 2006 13:41:47 -0000 1.148
+++ bfd/elf32-hppa.c 26 Oct 2006 15:39:51 -0000
@@ -3942,8 +3942,14 @@ elf32_hppa_relocate_section (bfd *output
/* r_symndx will be zero only for relocs against symbols
from removed linkonce sections, or sections discarded by
a linker script. */
- if (r_symndx == 0
- || (input_section->flags & SEC_ALLOC) == 0)
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (elf_hppa_howto_table + r_type, input_bfd,
+ contents + rela->r_offset);
+ break;
+ }
+
+ if ((input_section->flags & SEC_ALLOC) == 0)
break;
/* The reloc types handled here and this conditional
Index: bfd/elf32-i386.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-i386.c,v
retrieving revision 1.167
diff -u -p -r1.167 elf32-i386.c
--- bfd/elf32-i386.c 17 Oct 2006 13:41:46 -0000 1.167
+++ bfd/elf32-i386.c 26 Oct 2006 15:39:51 -0000
@@ -2395,17 +2395,12 @@ elf_i386_relocate_section (bfd *output_b
if (r_symndx == 0)
{
- /* r_symndx will be zero only for relocs against symbols from
- removed linkonce sections, or sections discarded by a linker
- script. For these relocs, we just want the section contents
- zeroed. Avoid any special processing in the switch below. */
- r_type = R_386_NONE;
-
- relocation = 0;
- if (howto->pc_relative)
- relocation = (input_section->output_section->vma
- + input_section->output_offset
- + rel->r_offset);
+ /* r_symndx will be zero only for relocs against symbols from
+ removed linkonce sections, or sections discarded by a linker
+ script. For these relocs, we just want the section contents
+ zeroed. Avoid any special processing. */
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ continue;
}
switch (r_type)
Index: bfd/elf32-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-ppc.c,v
retrieving revision 1.205
diff -u -p -r1.205 elf32-ppc.c
--- bfd/elf32-ppc.c 17 Oct 2006 13:41:47 -0000 1.205
+++ bfd/elf32-ppc.c 26 Oct 2006 15:39:52 -0000
@@ -6180,7 +6180,10 @@ ppc_elf_relocate_section (bfd *output_bf
a linker script. */
dodyn:
if (r_symndx == 0)
- break;
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ break;
+ }
/* Fall thru. */
if ((input_section->flags & SEC_ALLOC) == 0)
Index: bfd/elf32-s390.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-s390.c,v
retrieving revision 1.88
diff -u -p -r1.88 elf32-s390.c
--- bfd/elf32-s390.c 17 Oct 2006 13:41:47 -0000 1.88
+++ bfd/elf32-s390.c 26 Oct 2006 15:39:52 -0000
@@ -2543,8 +2543,13 @@ elf_s390_relocate_section (output_bfd, i
/* r_symndx will be zero only for relocs against symbols
from removed linkonce sections, or sections discarded by
a linker script. */
- if (r_symndx == 0
- || (input_section->flags & SEC_ALLOC) == 0)
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ break;
+ }
+
+ if ((input_section->flags & SEC_ALLOC) == 0)
break;
if ((info->shared
Index: bfd/elf64-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf64-ppc.c,v
retrieving revision 1.249
diff -u -p -r1.249 elf64-ppc.c
--- bfd/elf64-ppc.c 23 Oct 2006 03:20:56 -0000 1.249
+++ bfd/elf64-ppc.c 26 Oct 2006 15:39:53 -0000
@@ -10728,7 +10728,11 @@ ppc64_elf_relocate_section (bfd *output_
a linker script. */
dodyn:
if (r_symndx == 0)
- break;
+ {
+ _bfd_clear_contents (ppc64_elf_howto_table[r_type], input_bfd,
+ contents + rel->r_offset);
+ break;
+ }
/* Fall thru. */
dodyn2:
Index: bfd/elf64-s390.c
===================================================================
RCS file: /cvs/src/src/bfd/elf64-s390.c,v
retrieving revision 1.88
diff -u -p -r1.88 elf64-s390.c
--- bfd/elf64-s390.c 17 Oct 2006 13:41:47 -0000 1.88
+++ bfd/elf64-s390.c 26 Oct 2006 15:39:53 -0000
@@ -2522,8 +2522,13 @@ elf_s390_relocate_section (output_bfd, i
/* r_symndx will be zero only for relocs against symbols
from removed linkonce sections, or sections discarded by
a linker script. */
- if (r_symndx == 0
- || (input_section->flags & SEC_ALLOC) == 0)
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ break;
+ }
+
+ if ((input_section->flags & SEC_ALLOC) == 0)
break;
if ((info->shared
Index: bfd/elf64-x86-64.c
===================================================================
RCS file: /cvs/src/src/bfd/elf64-x86-64.c,v
retrieving revision 1.127
diff -u -p -r1.127 elf64-x86-64.c
--- bfd/elf64-x86-64.c 17 Oct 2006 13:41:47 -0000 1.127
+++ bfd/elf64-x86-64.c 26 Oct 2006 15:39:54 -0000
@@ -2370,8 +2370,13 @@ elf64_x86_64_relocate_section (bfd *outp
/* r_symndx will be zero only for relocs against symbols
from removed linkonce sections, or sections discarded by
a linker script. */
- if (r_symndx == 0
- || (input_section->flags & SEC_ALLOC) == 0)
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ break;
+ }
+
+ if ((input_section->flags & SEC_ALLOC) == 0)
break;
if ((info->shared
Index: bfd/elfxx-ia64.c
===================================================================
RCS file: /cvs/src/src/bfd/elfxx-ia64.c,v
retrieving revision 1.192
diff -u -p -r1.192 elfxx-ia64.c
--- bfd/elfxx-ia64.c 17 Oct 2006 13:41:47 -0000 1.192
+++ bfd/elfxx-ia64.c 26 Oct 2006 15:39:54 -0000
@@ -4751,6 +4751,12 @@ elfNN_ia64_relocate_section (output_bfd,
case R_IA64_LTV32LSB:
case R_IA64_LTV64MSB:
case R_IA64_LTV64LSB:
+ /* r_symndx will be zero only for relocs against symbols
+ from removed linkonce sections, or sections discarded by
+ a linker script. */
+ if (r_symndx == 0)
+ value = 0;
+
r = elfNN_ia64_install_value (hit_addr, value, r_type);
break;
Index: bfd/elfxx-mips.c
===================================================================
RCS file: /cvs/src/src/bfd/elfxx-mips.c,v
retrieving revision 1.189
diff -u -p -r1.189 elfxx-mips.c
--- bfd/elfxx-mips.c 20 Oct 2006 07:59:44 -0000 1.189
+++ bfd/elfxx-mips.c 26 Oct 2006 15:39:55 -0000
@@ -4312,6 +4312,11 @@ mips_elf_calculate_relocation (bfd *abfd
input_section))
return bfd_reloc_undefined;
}
+ else if (r_symndx == 0)
+ /* r_symndx will be zero only for relocs against symbols
+ from removed linkonce sections, or sections discarded by
+ a linker script. */
+ value = 0;
else
{
if (r_type != R_MIPS_REL32)
Index: bfd/elfxx-sparc.c
===================================================================
RCS file: /cvs/src/src/bfd/elfxx-sparc.c,v
retrieving revision 1.27
diff -u -p -r1.27 elfxx-sparc.c
--- bfd/elfxx-sparc.c 17 Oct 2006 13:41:47 -0000 1.27
+++ bfd/elfxx-sparc.c 26 Oct 2006 15:39:55 -0000
@@ -2755,8 +2755,13 @@ _bfd_sparc_elf_relocate_section (bfd *ou
/* r_symndx will be zero only for relocs against symbols
from removed linkonce sections, or sections discarded by
a linker script. */
- if (r_symndx == 0
- || (input_section->flags & SEC_ALLOC) == 0)
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ break;
+ }
+
+ if ((input_section->flags & SEC_ALLOC) == 0)
break;
if ((info->shared
Index: bfd/libbfd-in.h
===================================================================
RCS file: /cvs/src/src/bfd/libbfd-in.h,v
retrieving revision 1.66
diff -u -p -r1.66 libbfd-in.h
--- bfd/libbfd-in.h 19 Jun 2006 13:17:43 -0000 1.66
+++ bfd/libbfd-in.h 26 Oct 2006 15:39:56 -0000
@@ -547,6 +547,10 @@ extern bfd_reloc_status_type _bfd_final_
extern bfd_reloc_status_type _bfd_relocate_contents
(reloc_howto_type *, bfd *, bfd_vma, bfd_byte *);
+/* Clear a given location using a given howto. */
+extern void _bfd_clear_contents (reloc_howto_type *howto, bfd *input_bfd,
+ bfd_byte *location);
+
/* Link stabs in sections in the first pass. */
extern bfd_boolean _bfd_link_section_stabs
Index: bfd/libbfd.h
===================================================================
RCS file: /cvs/src/src/bfd/libbfd.h,v
retrieving revision 1.187
diff -u -p -r1.187 libbfd.h
--- bfd/libbfd.h 25 Oct 2006 06:49:20 -0000 1.187
+++ bfd/libbfd.h 26 Oct 2006 15:39:56 -0000
@@ -552,6 +552,10 @@ extern bfd_reloc_status_type _bfd_final_
extern bfd_reloc_status_type _bfd_relocate_contents
(reloc_howto_type *, bfd *, bfd_vma, bfd_byte *);
+/* Clear a given location using a given howto. */
+extern void _bfd_clear_contents (reloc_howto_type *howto, bfd *input_bfd,
+ bfd_byte *location);
+
/* Link stabs in sections in the first pass. */
extern bfd_boolean _bfd_link_section_stabs
Index: bfd/reloc.c
===================================================================
RCS file: /cvs/src/src/bfd/reloc.c,v
retrieving revision 1.158
diff -u -p -r1.158 reloc.c
--- bfd/reloc.c 25 Oct 2006 06:49:20 -0000 1.158
+++ bfd/reloc.c 26 Oct 2006 15:39:56 -0000
@@ -1545,6 +1545,72 @@ _bfd_relocate_contents (reloc_howto_type
return flag;
}
+/* Clear a given location using a given howto, by applying a relocation value
+ of zero and discarding any in-place addend. This is used for fixed-up
+ relocations against discarded symbols, to make ignorable debug or unwind
+ information more obvious. */
+
+void
+_bfd_clear_contents (reloc_howto_type *howto,
+ bfd *input_bfd,
+ bfd_byte *location)
+{
+ int size;
+ bfd_vma x = 0;
+
+ /* Get the value we are going to relocate. */
+ size = bfd_get_reloc_size (howto);
+ switch (size)
+ {
+ default:
+ case 0:
+ abort ();
+ case 1:
+ x = bfd_get_8 (input_bfd, location);
+ break;
+ case 2:
+ x = bfd_get_16 (input_bfd, location);
+ break;
+ case 4:
+ x = bfd_get_32 (input_bfd, location);
+ break;
+ case 8:
+#ifdef BFD64
+ x = bfd_get_64 (input_bfd, location);
+#else
+ abort ();
+#endif
+ break;
+ }
+
+ /* Zero out the unwanted bits of X. */
+ x &= ~howto->dst_mask;
+
+ /* Put the relocated value back in the object file. */
+ switch (size)
+ {
+ default:
+ case 0:
+ abort ();
+ case 1:
+ bfd_put_8 (input_bfd, x, location);
+ break;
+ case 2:
+ bfd_put_16 (input_bfd, x, location);
+ break;
+ case 4:
+ bfd_put_32 (input_bfd, x, location);
+ break;
+ case 8:
+#ifdef BFD64
+ bfd_put_64 (input_bfd, x, location);
+#else
+ abort ();
+#endif
+ break;
+ }
+}
+
/*
DOCDD
INODE
Index: ld/testsuite/ld-discard/zero-rel.d
===================================================================
RCS file: ld/testsuite/ld-discard/zero-rel.d
diff -N ld/testsuite/ld-discard/zero-rel.d
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-discard/zero-rel.d 26 Oct 2006 15:39:57 -0000
@@ -0,0 +1,8 @@
+#source: zero-rel.s
+#ld: -T discard.ld
+#objdump: -s -j .debug_info
+
+.*: file format .*elf.*
+
+Contents of section .debug_info:
+ 0000 0+( 0+)? +(\.+) .*
Index: ld/testsuite/ld-discard/zero-rel.s
===================================================================
RCS file: ld/testsuite/ld-discard/zero-rel.s
diff -N ld/testsuite/ld-discard/zero-rel.s
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ ld/testsuite/ld-discard/zero-rel.s 26 Oct 2006 15:39:57 -0000
@@ -0,0 +1,11 @@
+ .text
+ .globl _start
+_start:
+
+ .section .debug_info
+ .long .Ltext
+ .long .Ltext + 2
+
+ .section .text.exit,"ax"
+.Ltext:
+ .long 0
Index: bfd/elf32-sh.c
===================================================================
RCS file: /cvs/src/src/bfd/elf32-sh.c,v
retrieving revision 1.144
diff -u -p -r1.144 elf32-sh.c
--- bfd/elf32-sh.c 17 Oct 2006 13:41:47 -0000 1.144
+++ bfd/elf32-sh.c 26 Oct 2006 17:36:02 -0000
@@ -3557,6 +3557,15 @@ sh_elf_relocate_section (bfd *output_bfd
case R_SH_IMM_MEDHI16_PCREL:
case R_SH_IMM_HI16_PCREL:
#endif
+ /* r_symndx will be zero only for relocs against symbols
+ from removed linkonce sections, or sections discarded by
+ a linker script. */
+ if (r_symndx == 0)
+ {
+ _bfd_clear_contents (howto, input_bfd, contents + rel->r_offset);
+ continue;
+ }
+
if (info->shared
&& (h == NULL
|| ELF_ST_VISIBILITY (h->other) == STV_DEFAULT