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ELF/LD: Avoid producing hidden and internal dynamic symbols

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Always turn hidden and internal symbols which have a dynamic index into
local ones.  This is required by the the ELF gABI[1]:

"A hidden symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."

"An internal symbol contained in a relocatable object must be either
removed or converted to STB_LOCAL binding by the link-editor when the
relocatable object is included in an executable file or shared object."

The ELF linker usually respects this requirement, however in the case
where a dynamic symbol has been preallocated due to a reference of the
default export class aka visibility from the object being linked, and
then merged with a hidden or internal symbol definition from within the
same object, then the original export class is carried over to the
output dynamic symbol table, because while merging the generic ELF
linker only converts affected dynamic symbols to local when they are
defined or referenced by the object being linked and a dynamic object
involved in the link both at a time.

The dynamic symbol produced confuses then the dynamic loader at the run
time -- the hidden or internal export class is ignored and the symbol
follows preemption rules as with the default export class.

In the MIPS target it happens when `mips_elf_record_global_got_symbol'
creates a dynamic symbol when a call relocation is encountered.
Additionally if the undefined symbol referred by such a relocation does
specify the intended export class, then a local dynamic symbol is
created instead, which is harmless and allowed, but useless.  Normally
no local dynamic symbols are created, except for a single dummy one at
the beginning.

Correct the problem by removing the extra check for a dynamic symbol
being defined or referenced by the object being linked and a dynamic
object involved in the link both at a time.  The test cases included
cover the internal and hidden symbol cases, as well as a protected
symbol for a reference, the handling of which is unchanged by this fix.
Both cases described above are covered, that is where an internal or
hidden dynamic symbol is produced and where a local one is.

NB this change affects CRIS results where some symbols in the static
table produced in a final link are now converted from STV_HIDDEN to
STB_LOCAL.  This happens whenever the `elf_backend_hide_symbol' handler
is called, so the affected symbols must have been chosen for entering
into the dynamic symbol table, except in these test cases no such symbol
table is produced.  In fully linked binaries the static symbol table is
only used for debugging though, so such a change is fine.

References:

[1] "System V Application Binary Interface - DRAFT - 24 April 2001",
    The Santa Cruz Operation, Inc., "Symbol Table",
    <http://www.sco.com/developers/gabi/2001-04-24/ch4.symtab.html>

	bfd/
	PR ld/19908
	* elflink.c (elf_link_add_object_symbols): Always turn hidden
	and internal symbols which have a dynamic index into local
	ones.

	ld/
	PR ld/19908
	* testsuite/ld-cris/tls-e-20.d: Adjust for hidden symbol
	handling fix.
	* testsuite/ld-cris/tls-e-20a.d: Likewise.
	* testsuite/ld-cris/tls-e-21.d: Likewise.
	* testsuite/ld-cris/tls-e-23.d: Likewise.
	* testsuite/ld-cris/tls-e-80.d: Likewise.
	* testsuite/ld-cris/tls-gd-3h.d: Likewise.
	* testsuite/ld-cris/tls-leie-19.d: Likewise.
	* testsuite/ld-mips-elf/export-class-ref-lib.sd: New test.
	* testsuite/ld-mips-elf/export-hidden-ref.sd: New test.
	* testsuite/ld-mips-elf/export-internal-ref.sd: New test.
	* testsuite/ld-mips-elf/export-protected-ref.sd: New test.
	* testsuite/ld-mips-elf/export-class-ref-f0.s: New test source.
	* testsuite/ld-mips-elf/export-class-ref-f1.s: New test source.
	* testsuite/ld-mips-elf/export-class-ref-f2.s: New test source.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
This commit is contained in:
Maciej W. Rozycki 2016-04-05 15:10:05 +01:00
parent a9fa4610b8
commit 1f599d0e7b
19 changed files with 173 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2016-04-05 Maciej W. Rozycki <macro@imgtec.com>
* elflink.c (elf_link_add_object_symbols): Always turn hidden
and internal symbols which have a dynamic index into local
ones.
2016-04-04 Nick Clifton <nickc@redhat.com>
PR 19872

2
bfd/elflink.c
View File

@ -4583,7 +4583,7 @@ error_free_dyn:
goto error_free_vers;
}
}
else if (dynsym && h->dynindx != -1)
else if (h->dynindx != -1)
/* If the symbol already has a dynamic index, but
visibility says it should not be visible, turn it into
a local symbol. */

20
ld/ChangeLog
View File

@ -1,3 +1,23 @@
2016-04-05 Maciej W. Rozycki <macro@imgtec.com>
PR ld/19908
* testsuite/ld-cris/tls-e-20.d: Adjust for hidden symbol
handling fix.
* testsuite/ld-cris/tls-e-20a.d: Likewise.
* testsuite/ld-cris/tls-e-21.d: Likewise.
* testsuite/ld-cris/tls-e-23.d: Likewise.
* testsuite/ld-cris/tls-e-80.d: Likewise.
* testsuite/ld-cris/tls-gd-3h.d: Likewise.
* testsuite/ld-cris/tls-leie-19.d: Likewise.
* testsuite/ld-mips-elf/export-class-ref-lib.sd: New test.
* testsuite/ld-mips-elf/export-hidden-ref.sd: New test.
* testsuite/ld-mips-elf/export-internal-ref.sd: New test.
* testsuite/ld-mips-elf/export-protected-ref.sd: New test.
* testsuite/ld-mips-elf/export-class-ref-f0.s: New test source.
* testsuite/ld-mips-elf/export-class-ref-f1.s: New test source.
* testsuite/ld-mips-elf/export-class-ref-f2.s: New test source.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
2016-04-05 Cupertino Miranda <cmiranda@synopsys.com>
* testsuite/ld-discard/extern.d: Removed xfail for ARC.

2
ld/testsuite/ld-cris/tls-e-20.d
View File

@ -35,8 +35,8 @@ SYMBOL TABLE:
0+80094 l d \.text 0+ \.text
0+820b0 l d \.tdata 0+ \.tdata
0+820bc l d \.got 0+ \.got
0+ l \.tdata 0+4 x
0+820bc l O \.got 0+ _GLOBAL_OFFSET_TABLE_
0+ g \.tdata 0+4 \.hidden x
0+80098 g F \.text 0+6 tlsdsofn2
0+8 g \.tdata 0+4 \.hidden x2
0+80094 g \.text 0+ _start

2
ld/testsuite/ld-cris/tls-e-20a.d
View File

@ -43,8 +43,8 @@ SYMBOL TABLE:
0+ l df \*ABS\* 0+ .*
0+ l \.tdata 0+80 tls128
0+ l df \*ABS\* 0+ .*
0+80 l \.tdata 0+4 x
0+82168 l O \.got 0+ _GLOBAL_OFFSET_TABLE_
0+80 g \.tdata 0+4 \.hidden x
0+800c4 g F \.text 0+6 tlsdsofn2
0+821b4 g O \.data 0+4 got7var5
0+88 g \.tdata 0+4 \.hidden x2

2
ld/testsuite/ld-cris/tls-e-21.d
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@ -19,7 +19,7 @@ private flags = 0:
#...
SYMBOL TABLE:
#...
0+80 g \.tdata 0+4 \.hidden x
0+80 l \.tdata 0+4 x
#...
Contents of section \.text:
#...

2
ld/testsuite/ld-cris/tls-e-23.d
View File

@ -19,7 +19,7 @@ private flags = 0:
#...
SYMBOL TABLE:
#...
0+80 g \.tdata 0+4 \.hidden x
0+80 l \.tdata 0+4 x
#...
Contents of section \.text:
#...

2
ld/testsuite/ld-cris/tls-e-80.d
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@ -42,8 +42,8 @@ SYMBOL TABLE:
0+820c0 l d \.tdata 0+ \.tdata
0+820d0 l d \.tbss 0+ \.tbss
0+820d0 l d \.got 0+ \.got
0+ l \.tdata 0+4 x
0+820d0 l O \.got 0+ _GLOBAL_OFFSET_TABLE_
0+ g \.tdata 0+4 \.hidden x
0+800a0 g F \.text 0+6 tlsdsofn2
0+800a8 g F \.text 0+6 tlsfn12
0+c g \.tdata 0+4 \.hidden x2

2
ld/testsuite/ld-cris/tls-gd-3h.d
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@ -19,7 +19,7 @@ private flags = 0:
#...
SYMBOL TABLE:
#...
0+80 g \.tdata 0+4 \.hidden x
0+80 l \.tdata 0+4 x
#...
Contents of section \.text:
#...

8
ld/testsuite/ld-cris/tls-leie-19.d
View File

@ -26,14 +26,14 @@ private flags = 0:
CONTENTS.*
SYMBOL TABLE:
#...
0+84 l \.tdata 0+4 x2
#...
0+80 l \.tdata 0+4 x1
#...
0+88 g .tdata 0+4 x
#...
0+84 g \.tdata 0+4 \.hidden x2
#...
0+8c g .tdata 0+4 z
#...
0+80 g \.tdata 0+4 \.hidden x1
#...
Contents of section \.text:
#...
Contents of section \.got:

37
ld/testsuite/ld-mips-elf/export-class-ref-f0.s Normal file
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@ -0,0 +1,37 @@
.abicalls
.text
.if refv == 3
.protected f1
.elseif refv == 2
.hidden f1
.elseif refv == 1
.internal f1
.endif
.globl f0
.ent f0
f0:
.frame $sp, 32, $31
.mask 0x80000000, -4
.fmask 0x00000000, 0
.set noreorder
.cpload $25
.set reorder
addiu $sp, $sp, -32
sw $31, 28($sp)
.cprestore 16
lw $25, %call16(f1)($28)
jalr $25
lw $28, 16($sp)
lw $25, %call16(f2)($28)
jalr $25
lw $28, 16($sp)
move $2, $0
lw $31, 28($sp)
addiu $sp, $sp, 32
jr $31
.end f0

18
ld/testsuite/ld-mips-elf/export-class-ref-f1.s Normal file
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@ -0,0 +1,18 @@
.abicalls
.text
.globl f1
.if defv == 3
.protected f1
.elseif defv == 2
.hidden f1
.elseif defv == 1
.internal f1
.endif
.ent f1
f1:
.frame $sp, 0, $31
.mask 0x00000000, 0
.fmask 0x00000000, 0
jr $31
.end f1

20
ld/testsuite/ld-mips-elf/export-class-ref-f2.s Normal file
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@ -0,0 +1,20 @@
.abicalls
.text
.globl f1
.ent f1
f1:
.frame $sp, 0, $31
.mask 0x00000000, 0
.fmask 0x00000000, 0
jr $31
.end f1
.globl f2
.ent f2
f2:
.frame $sp, 0, $31
.mask 0x00000000, 0
.fmask 0x00000000, 0
jr $31
.end f2

6
ld/testsuite/ld-mips-elf/export-class-ref-lib.sd Normal file
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@ -0,0 +1,6 @@
# Make sure `f1' is present in the dynamic symbol table, e.g.:
# Num: Value Size Type Bind Vis Ndx Name
# 6: 000002d0 8 FUNC GLOBAL DEFAULT 7 f1
#...
*[0-9]+: +[0-9a-f]+ +[0-9]+ FUNC +GLOBAL +DEFAULT +[0-9]+ f1
#pass

7
ld/testsuite/ld-mips-elf/export-hidden-ref.sd Normal file
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@ -0,0 +1,7 @@
# Make sure no hidden symbol is present in the dynamic symbol table, e.g.:
# Num: Value Size Type Bind Vis Ndx Name
# 6: 004003f0 8 FUNC GLOBAL HIDDEN 8 f1
#failif
#...
.+ +HIDDEN +.+ +f1
#pass

7
ld/testsuite/ld-mips-elf/export-internal-ref.sd Normal file
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@ -0,0 +1,7 @@
# Make sure no internal symbol is present in the dynamic symbol table, e.g.:
# Num: Value Size Type Bind Vis Ndx Name
# 6: 004003f0 8 FUNC GLOBAL INTERNAL 8 f1
#failif
#...
.+ +INTERNAL +.+ +f1
#pass

7
ld/testsuite/ld-mips-elf/export-local-ref.sd Normal file
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@ -0,0 +1,7 @@
# Make sure no local symbol is present in the dynamic symbol table, e.g.:
# Num: Value Size Type Bind Vis Ndx Name
# 6: 004003f0 8 FUNC LOCAL DEFAULT 8 f1
#failif
#...
.+ +LOCAL +.+ +f1
#pass

6
ld/testsuite/ld-mips-elf/export-protected-ref.sd Normal file
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@ -0,0 +1,6 @@
# Make sure a protected symbol is present in the dynamic symbol table, e.g.:
# Num: Value Size Type Bind Vis Ndx Name
# 6: 004003f0 8 FUNC GLOBAL PROTECTED 8 f1
#...
*[0-9]+: +[0-9a-f]+ +[0-9]+ FUNC +GLOBAL +PROTECTED +[0-9]+ f1
#pass

28
ld/testsuite/ld-mips-elf/mips-elf.exp
View File

@ -899,3 +899,31 @@ if { $linux_gnu } {
n32 -1 1 umips
}
}
# PR ld/19908 export class tests.
if { $linux_gnu } {
run_ld_link_tests [list \
[list "Shared library for MIPS export class symbol reference tests" \
"$abi_ldflags(o32) -shared" "" \
"$abi_asflags(o32)" \
{ export-class-ref-f2.s } \
{ { readelf --dyn-syms export-class-ref-lib.sd } } \
"export-class-ref-lib.so"]]
foreach { class flag } { internal 1 hidden 2 protected 3 } {
run_ld_link_tests [list \
[list "MIPS $class symbol reference test 1" \
"$abi_ldflags(o32) -e f0" "tmpdir/export-class-ref-lib.so" \
"$abi_asflags(o32) --defsym defv=$flag" \
{ export-class-ref-f0.s export-class-ref-f1.s } \
[list [list readelf --dyn-syms export-$class-ref.sd] \
[list readelf --dyn-syms export-local-ref.sd]] \
"export-$class-ref"] \
[list "MIPS $class symbol reference test 2" \
"$abi_ldflags(o32) -e f0" "tmpdir/export-class-ref-lib.so" \
"$abi_asflags(o32) --defsym defv=$flag --defsym refv=$flag" \
{ export-class-ref-f0.s export-class-ref-f1.s } \
[list [list readelf --dyn-syms export-$class-ref.sd] \
[list readelf --dyn-syms export-local-ref.sd]] \
"export-$class-ref"]]
}
}