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Taking an undefined function's address in an executable

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doesn't always mean you need to define a function symbol on plt code.
If all references are in read-write sections, then using dynamic relocs
is OK.

bfd/
	* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Clear
	pointer_equality_needed when !readonly_dynrelocs.
	* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
ld/testsuite/
	* ld-powerpc/ambiguousv1.d: Match symbol table too.
	* ld-powerpc/ambiguousv2.d: Likewise.
	* ld-powerpc/ambiguousv1b.d: New.
	* ld-powerpc/ambiguousv2b.d: New.
	* ld-powerpc/powerpc.exp: Run new tests.
This commit is contained in:
Alan Modra 2014-07-02 15:07:18 +09:30
parent 9b11e3a732
commit d1eca1e41d
10 changed files with 226 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2014-07-02 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_adjust_dynamic_symbol): Clear
pointer_equality_needed when !readonly_dynrelocs.
* elf64-ppc.c (ppc64_elf_adjust_dynamic_symbol): Likewise.
2014-07-02 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_check_relocs): Set DF_STATIC_TLS for PIEs too.

24
bfd/elf32-ppc.c
View File

@ -5506,9 +5506,21 @@ ppc_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
will go to this object, or will remain undefined. */
h->plt.plist = NULL;
h->needs_plt = 0;
h->pointer_equality_needed = 0;
}
else
{
/* Taking a function's address in a read/write section
doesn't require us to define the function symbol in the
executable on a global entry stub. A dynamic reloc can
be used instead. */
if (h->pointer_equality_needed
&& !readonly_dynrelocs (h))
{
h->pointer_equality_needed = 0;
h->non_got_ref = 0;
}
/* After adjust_dynamic_symbol, non_got_ref set in the
non-shared case means that we have allocated space in
.dynbss for the symbol and thus dyn_relocs for this
@ -5518,12 +5530,12 @@ ppc_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
relocations against this symbol to the PLT entry. Allow
dynamic relocs if the reference is weak, and the dynamic
relocs will not cause text relocation. */
if (!h->ref_regular_nonweak
&& h->non_got_ref
&& h->type != STT_GNU_IFUNC
&& !htab->is_vxworks
&& !ppc_elf_hash_entry (h)->has_sda_refs
&& !readonly_dynrelocs (h))
else if (!h->ref_regular_nonweak
&& h->non_got_ref
&& h->type != STT_GNU_IFUNC
&& !htab->is_vxworks
&& !ppc_elf_hash_entry (h)->has_sda_refs
&& !readonly_dynrelocs (h))
h->non_got_ref = 0;
}
return TRUE;

20
bfd/elf64-ppc.c
View File

@ -6993,9 +6993,21 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
{
h->plt.plist = NULL;
h->needs_plt = 0;
h->pointer_equality_needed = 0;
}
else if (abiversion (info->output_bfd) == 2)
{
/* Taking a function's address in a read/write section
doesn't require us to define the function symbol in the
executable on a global entry stub. A dynamic reloc can
be used instead. */
if (h->pointer_equality_needed
&& !readonly_dynrelocs (h))
{
h->pointer_equality_needed = 0;
h->non_got_ref = 0;
}
/* After adjust_dynamic_symbol, non_got_ref set in the
non-shared case means that we have allocated space in
.dynbss for the symbol and thus dyn_relocs for this
@ -7005,10 +7017,10 @@ ppc64_elf_adjust_dynamic_symbol (struct bfd_link_info *info,
relocations against this symbol to the PLT entry. Allow
dynamic relocs if the reference is weak, and the dynamic
relocs will not cause text relocation. */
if (!h->ref_regular_nonweak
&& h->non_got_ref
&& h->type != STT_GNU_IFUNC
&& !readonly_dynrelocs (h))
else if (!h->ref_regular_nonweak
&& h->non_got_ref
&& h->type != STT_GNU_IFUNC
&& !readonly_dynrelocs (h))
h->non_got_ref = 0;
/* If making a plt entry, then we don't need copy relocs. */

8
ld/testsuite/ChangeLog
View File

@ -1,3 +1,11 @@
2014-07-02 Alan Modra <amodra@gmail.com>
* ld-powerpc/ambiguousv1.d: Match symbol table too.
* ld-powerpc/ambiguousv2.d: Likewise.
* ld-powerpc/ambiguousv1b.d: New.
* ld-powerpc/ambiguousv2b.d: New.
* ld-powerpc/powerpc.exp: Run new tests.
2014-06-25 Kyle McMartin <kyle@redhat.com>
* ld-arm/tls-gdierelax2.d: Fix expected offsets.

40
ld/testsuite/ld-powerpc/ambiguousv1.d
View File

@ -1,12 +1,44 @@
#source: startv1.s
#source: funref.s
#as: -a64
#ld: -melf64ppc
#ld: -melf64ppc --emit-stub-syms
#ld_after_inputfiles: tmpdir/funv1.so
#readelf: -r --wide
# check that we do the right thing with funref.s that doesn't have
# anything to mark it as ELFv1 or ELFv2
#readelf: -rs --wide
# Check that we do the right thing with funref.s that doesn't have
# anything to mark it as ELFv1 or ELFv2. We should get a dynamic
# reloc on the function address, and my_func should be undefined
# dynamic with value zero.
Relocation section .* contains 1 entries:
.*
.* R_PPC64_ADDR64 +0+ my_func \+ 0
Symbol table '\.dynsym' contains 5 entries:
.*
0: .*
1: 0+00000000 0 FUNC GLOBAL DEFAULT UND my_func
2: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 __bss_start
3: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _edata
4: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _end
Symbol table '\.symtab' contains 19 entries:
Num: Value Size Type Bind Vis Ndx Name
0: .*
1: 0+10000158 0 SECTION LOCAL DEFAULT 1
2: 0+10000170 0 SECTION LOCAL DEFAULT 2
3: 0+10000198 0 SECTION LOCAL DEFAULT 3
4: 0+10000210 0 SECTION LOCAL DEFAULT 4
5: 0+10000248 0 SECTION LOCAL DEFAULT 5
6: 0+10000260 0 SECTION LOCAL DEFAULT 6
7: 0+10000264 0 SECTION LOCAL DEFAULT 7
8: 0+10010268 0 SECTION LOCAL DEFAULT 8
9: 0+10010368 0 SECTION LOCAL DEFAULT 9
10: 0+10010370 0 SECTION LOCAL DEFAULT 10
11: 0+10010388 0 SECTION LOCAL DEFAULT 11
12: 0+10010268 0 OBJECT LOCAL DEFAULT 8 _DYNAMIC
13: 0+10010368 0 NOTYPE GLOBAL DEFAULT 9 func_tab
14: 0+00000000 0 FUNC GLOBAL DEFAULT UND my_func
15: 0+10010370 0 FUNC GLOBAL DEFAULT 10 _start
16: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 __bss_start
17: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _edata
18: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _end

45
ld/testsuite/ld-powerpc/ambiguousv1b.d Normal file
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@ -0,0 +1,45 @@
#source: startv1.s
#source: funref2.s
#as: -a64
#ld: -melf64ppc --emit-stub-syms
#ld_after_inputfiles: tmpdir/funv1.so
#readelf: -rs --wide
# Check that we do the right thing with funref2.s that doesn't have
# anything to mark it as ELFv1 or ELFv2. Since my_func address is
# taken in a read-only section we should get a copy reloc for the OPD
# entry.
Relocation section .* contains 1 entries:
.*
.* R_PPC64_COPY .* my_func \+ 0
Symbol table '\.dynsym' contains 5 entries:
.*
0: .*
1: 0+10010390 4 FUNC GLOBAL DEFAULT 12 my_func
2: 0+10010390 0 NOTYPE GLOBAL DEFAULT 12 __bss_start
3: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _edata
4: 0+10010398 0 NOTYPE GLOBAL DEFAULT 12 _end
Symbol table '\.symtab' contains 20 entries:
.*
0: .*
1: 0+10000158 0 SECTION LOCAL DEFAULT 1
2: 0+10000170 0 SECTION LOCAL DEFAULT 2
3: 0+10000198 0 SECTION LOCAL DEFAULT 3
4: 0+10000210 0 SECTION LOCAL DEFAULT 4
5: 0+10000248 0 SECTION LOCAL DEFAULT 5
6: 0+10000260 0 SECTION LOCAL DEFAULT 6
7: 0+10000264 0 SECTION LOCAL DEFAULT 7
8: 0+1000026c 0 SECTION LOCAL DEFAULT 8
9: 0+10010270 0 SECTION LOCAL DEFAULT 9
10: 0+10010370 0 SECTION LOCAL DEFAULT 10
11: 0+10010388 0 SECTION LOCAL DEFAULT 11
12: 0+10010390 0 SECTION LOCAL DEFAULT 12
13: 0+10010270 0 OBJECT LOCAL DEFAULT 9 _DYNAMIC
14: 0+10000264 0 NOTYPE GLOBAL DEFAULT 7 func_tab
15: 0+10010390 4 FUNC GLOBAL DEFAULT 12 my_func
16: 0+10010370 0 FUNC GLOBAL DEFAULT 10 _start
17: 0+10010390 0 NOTYPE GLOBAL DEFAULT 12 __bss_start
18: 0+10010390 0 NOTYPE GLOBAL DEFAULT 11 _edata
19: 0+10010398 0 NOTYPE GLOBAL DEFAULT 12 _end

49
ld/testsuite/ld-powerpc/ambiguousv2.d
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@ -1,12 +1,51 @@
#source: startv2.s
#source: funref.s
#as: -a64
#ld: -melf64ppc
#ld: -melf64ppc --emit-stub-syms
#ld_after_inputfiles: tmpdir/funv2.so
#readelf: -r --wide
# check that we do the right thing with funref.s that doesn't have
# anything to mark it as ELFv1 or ELFv2
#readelf: -rs --wide
# Check that we do the right thing with funref.s that doesn't have
# anything to mark it as ELFv1 or ELFv2. We should get a dynamic
# reloc on the function address, not have a global entry stub, and
# my_func should be undefined dynamic with value zero.
# FIXME someday: No need for a plt entry.
Relocation section .*contains 1 entries:
Relocation section .* contains 1 entries:
.*
.* R_PPC64_ADDR64 .* my_func \+ 0
Relocation section .* contains 1 entries:
.*
.* R_PPC64_JMP_SLOT .* my_func \+ 0
Symbol table '\.dynsym' contains 5 entries:
.*
0: .*
1: 0+00000000 0 FUNC GLOBAL DEFAULT UND my_func
2: 0+10010438 0 NOTYPE GLOBAL DEFAULT 12 __bss_start
3: 0+10010438 0 NOTYPE GLOBAL DEFAULT 11 _edata
4: 0+10010450 0 NOTYPE GLOBAL DEFAULT 12 _end
Symbol table '\.symtab' contains 21 entries:
.*
0: .*
1: 0+10000158 0 SECTION LOCAL DEFAULT 1
2: 0+10000170 0 SECTION LOCAL DEFAULT 2
3: 0+10000198 0 SECTION LOCAL DEFAULT 3
4: 0+10000210 0 SECTION LOCAL DEFAULT 4
5: 0+10000248 0 SECTION LOCAL DEFAULT 5
6: 0+10000260 0 SECTION LOCAL DEFAULT 6
7: 0+10000278 0 SECTION LOCAL DEFAULT 7
8: 0+100002c4 0 SECTION LOCAL DEFAULT 8
9: 0+100102c8 0 SECTION LOCAL DEFAULT 9
10: 0+10010428 0 SECTION LOCAL DEFAULT 10
11: 0+10010430 0 SECTION LOCAL DEFAULT 11
12: 0+10010438 0 SECTION LOCAL DEFAULT 12
13: 0+100102c8 0 OBJECT LOCAL DEFAULT 9 _DYNAMIC
14: 0+10000288 0 NOTYPE LOCAL DEFAULT 7 __glink_PLTresolve
15: 0+10010428 0 NOTYPE GLOBAL DEFAULT 10 func_tab
16: 0+00000000 0 FUNC GLOBAL DEFAULT UND my_func
17: 0+10000278 0 NOTYPE GLOBAL DEFAULT 7 _start
18: 0+10010438 0 NOTYPE GLOBAL DEFAULT 12 __bss_start
19: 0+10010438 0 NOTYPE GLOBAL DEFAULT 11 _edata
20: 0+10010450 0 NOTYPE GLOBAL DEFAULT 12 _end

47
ld/testsuite/ld-powerpc/ambiguousv2b.d Normal file
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@ -0,0 +1,47 @@
#source: startv2.s
#source: funref2.s
#as: -a64
#ld: -melf64ppc --emit-stub-syms
#ld_after_inputfiles: tmpdir/funv2.so
#readelf: -rs --wide
# Check that we do the right thing with funref2.s that doesn't have
# anything to mark it as ELFv1 or ELFv2. Since my_func address is
# taken in a read-only section we should get a plt entry, a global
# entry stub, and my_func should be undefined dynamic with non-zero
# value.
Relocation section .* contains 1 entries:
.*
.* R_PPC64_JMP_SLOT .* my_func \+ 0
Symbol table '\.dynsym' contains 5 entries:
.*
0: .*
1: 0+100002b8 0 FUNC GLOBAL DEFAULT UND my_func
2: 0+10010408 0 NOTYPE GLOBAL DEFAULT 11 __bss_start
3: 0+10010408 0 NOTYPE GLOBAL DEFAULT 10 _edata
4: 0+10010420 0 NOTYPE GLOBAL DEFAULT 11 _end
Symbol table '\.symtab' contains 21 entries:
.*
0: .*
1: 0+10000158 0 SECTION LOCAL DEFAULT 1
2: 0+10000170 0 SECTION LOCAL DEFAULT 2
3: 0+10000198 0 SECTION LOCAL DEFAULT 3
4: 0+10000210 0 SECTION LOCAL DEFAULT 4
5: 0+10000248 0 SECTION LOCAL DEFAULT 5
6: 0+10000260 0 SECTION LOCAL DEFAULT 6
7: 0+100002c8 0 SECTION LOCAL DEFAULT 7
8: 0+100002d0 0 SECTION LOCAL DEFAULT 8
9: 0+100102d0 0 SECTION LOCAL DEFAULT 9
10: 0+10010400 0 SECTION LOCAL DEFAULT 10
11: 0+10010408 0 SECTION LOCAL DEFAULT 11
12: 0+100102d0 0 OBJECT LOCAL DEFAULT 9 _DYNAMIC
13: 0+100002b8 0 NOTYPE LOCAL DEFAULT 6 00000011\.global_entry\.my_func
14: 0+10000270 0 NOTYPE LOCAL DEFAULT 6 __glink_PLTresolve
15: 0+100002c8 0 NOTYPE GLOBAL DEFAULT 7 func_tab
16: 0+100002b8 0 FUNC GLOBAL DEFAULT UND my_func
17: 0+10000260 0 NOTYPE GLOBAL DEFAULT 6 _start
18: 0+10010408 0 NOTYPE GLOBAL DEFAULT 11 __bss_start
19: 0+10010408 0 NOTYPE GLOBAL DEFAULT 10 _edata
20: 0+10010420 0 NOTYPE GLOBAL DEFAULT 11 _end

4
ld/testsuite/ld-powerpc/funref2.s Normal file
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@ -0,0 +1,4 @@
.section .rodata,"a",@progbits
.globl func_tab
func_tab:
.dc.a my_func

2
ld/testsuite/ld-powerpc/powerpc.exp
View File

@ -275,7 +275,9 @@ if [ supports_ppc64 ] then {
run_dump_test "elfv2-2so"
run_dump_test "elfv2-2exe"
run_dump_test "ambiguousv1"
run_dump_test "ambiguousv1b"
run_dump_test "ambiguousv2"
run_dump_test "ambiguousv2b"
}
if { [istarget "powerpc*-eabi*"] } {