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BFD: Prevent writing the MIPS _gp_disp symbol into symbol tables 

The _gp_disp is a magic symbol, always implicitly defined by the linker.
It does not make a sense to write it into symbol tables for output files.
Moreover, now if the linker gets a version script, the _gp_disp symbol
gets zero version definition index.  The zero index means[1]:

"The symbol is local, not available outside the object."

But the _gp_disp symbol has GLOBAL binding.  That confuses some tools
like for example the LLD linker when they get such files as inputs.

This patch fixes the problem - it prevents writing the _gp_disp symbol
in regular and dynamic symbol tables.

This was tested by running LD test suite on a mipsel-linux board.

References:

[1] "Linux Standard Base Specification", Section "10.7.2 Symbol
    Version Table", p. 32

2018-05-03  Simon Atanasyan  <simon@atanasyan.com>

bfd/

	* elf32-mips.c: (elf32_mips_fixup_symbol): New function.
	(elf_backend_fixup_symbol): New macro.
	* elfxx-mips.c: (mips_elf_output_extsym): Discard _gp_disp
	handling.
	(_bfd_mips_elf_finish_dynamic_symbol): Likewise.

ld/

	* testsuite/ld-mips-elf/gp-disp-sym.d: New test.
	* testsuite/ld-mips-elf/gp-disp-sym.s: New test source.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
	* testsuite/ld-mips-elf/mips16-pic-2.ad: Update for _gp_disp
	symbol removal.
	* testsuite/ld-mips-elf/mips16-pic-2.nd: Likewise.
	* testsuite/ld-mips-elf/pic-and-nonpic-3a.dd: Likewise.
	* testsuite/ld-mips-elf/tlslib-o32-hidden.got: Likewise.
	* testsuite/ld-mips-elf/tlslib-o32-ver.got: Likewise.
	* testsuite/ld-mips-elf/tlslib-o32.got: Likewise.
This commit is contained in:
Simon Atanasyan 2018-05-03 17:17:46 +01:00 committed by Maciej W. Rozycki
parent bd732259bd
commit 3be08ea472
13 changed files with 76 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
bfd/ChangeLog
View File

@ -1,3 +1,11 @@
2018-05-03 Simon Atanasyan <simon@atanasyan.com>
* elf32-mips.c: (elf32_mips_fixup_symbol): New function.
(elf_backend_fixup_symbol): New macro.
* elfxx-mips.c: (mips_elf_output_extsym): Discard _gp_disp
handling.
(_bfd_mips_elf_finish_dynamic_symbol): Likewise.
2018-04-30 Francois H. Theron <francois.theron@netronome.com>
* Makefile.am: Added NFP files to build.

12
bfd/elf32-mips.c
View File

@ -2420,6 +2420,17 @@ elf32_mips_write_core_note (bfd *abfd, char *buf, int *bufsiz, int note_type,
}
}
}
/* Remove the magic _gp_disp symbol from the symbol tables. */
static bfd_boolean
elf32_mips_fixup_symbol (struct bfd_link_info *info,
struct elf_link_hash_entry *h)
{
if (strcmp (h->root.root.string, "_gp_disp") == 0)
_bfd_elf_link_hash_hide_symbol (info, h, TRUE);
return TRUE;
}
/* Depending on the target vector we generate some version of Irix
executables or "normal" MIPS ELF ABI executables. */
@ -2523,6 +2534,7 @@ static const struct ecoff_debug_swap mips_elf32_ecoff_debug_swap = {
#define elf_backend_gc_mark_hook _bfd_mips_elf_gc_mark_hook
#define elf_backend_copy_indirect_symbol \
_bfd_mips_elf_copy_indirect_symbol
#define elf_backend_fixup_symbol elf32_mips_fixup_symbol
#define elf_backend_grok_prstatus elf32_mips_grok_prstatus
#define elf_backend_grok_psinfo elf32_mips_grok_psinfo
#define elf_backend_ecoff_debug_swap &mips_elf32_ecoff_debug_swap

12
bfd/elfxx-mips.c
View File

@ -2903,12 +2903,6 @@ mips_elf_output_extsym (struct mips_elf_link_hash_entry *h, void *data)
h->esym.asym.value =
mips_elf_hash_table (einfo->info)->procedure_count;
}
else if (strcmp (name, "_gp_disp") == 0 && ! NEWABI_P (einfo->abfd))
{
h->esym.asym.sc = scAbs;
h->esym.asym.st = stLabel;
h->esym.asym.value = elf_gp (einfo->abfd);
}
else
h->esym.asym.sc = scUndefined;
}
@ -10976,12 +10970,6 @@ _bfd_mips_elf_finish_dynamic_symbol (bfd *output_bfd,
sym->st_info = ELF_ST_INFO (STB_GLOBAL, STT_SECTION);
sym->st_value = 1;
}
else if (strcmp (name, "_gp_disp") == 0 && ! NEWABI_P (output_bfd))
{
sym->st_shndx = SHN_ABS;
sym->st_info = ELF_ST_INFO (STB_GLOBAL, STT_SECTION);
sym->st_value = elf_gp (output_bfd);
}
else if (SGI_COMPAT (output_bfd))
{
if (strcmp (name, mips_elf_dynsym_rtproc_names[0]) == 0

13
ld/ChangeLog
View File

@ -1,3 +1,16 @@
2018-05-03 Simon Atanasyan <simon@atanasyan.com>
* testsuite/ld-mips-elf/gp-disp-sym.d: New test.
* testsuite/ld-mips-elf/gp-disp-sym.s: New test source.
* testsuite/ld-mips-elf/mips-elf.exp: Run the new test.
* testsuite/ld-mips-elf/mips16-pic-2.ad: Update for _gp_disp
symbol removal.
* testsuite/ld-mips-elf/mips16-pic-2.nd: Likewise.
* testsuite/ld-mips-elf/pic-and-nonpic-3a.dd: Likewise.
* testsuite/ld-mips-elf/tlslib-o32-hidden.got: Likewise.
* testsuite/ld-mips-elf/tlslib-o32-ver.got: Likewise.
* testsuite/ld-mips-elf/tlslib-o32.got: Likewise.
2018-04-27 Maciej W. Rozycki <macro@mips.com>
* testsuite/ld-mips-elf/bal-jalx-pic.d: Only run for

9
ld/testsuite/ld-mips-elf/gp-disp-sym.d Normal file
View File

@ -0,0 +1,9 @@
#name: MIPS _gp_disp removal from symbol tables
#ld: -shared
#objdump: -tT
#target: [check_shared_lib_support]
#failif
#...
.*_gp_disp
#pass

5
ld/testsuite/ld-mips-elf/gp-disp-sym.s Normal file
View File

@ -0,0 +1,5 @@
.global foo
.text
foo:
lui $t0, %hi(_gp_disp)
addi $t0, $t0, %lo(_gp_disp)

4
ld/testsuite/ld-mips-elf/mips-elf.exp
View File

@ -1255,3 +1255,7 @@ run_dump_test "mips-abiflags-1"
run_dump_test "mips-abiflags-1r"
run_dump_test "mips-abiflags-2"
run_dump_test "mips-abiflags-2r"
# Test that _gp_disp symbol is not present in symbol tables.
run_dump_test "gp-disp-sym" [list [list as $abi_asflags(o32)] \
[list ld $abi_ldflags(o32)]]

4
ld/testsuite/ld-mips-elf/mips16-pic-2.ad
View File

@ -1,6 +1,6 @@
# [MIPS_GOTSYM, MIPS_SYMTABNO) covers used4...used7.
#...
.* \(MIPS_SYMTABNO\) * 8
.* \(MIPS_SYMTABNO\) * 7
#...
.* \(MIPS_GOTSYM\) * 0x4
.* \(MIPS_GOTSYM\) * 0x3
#pass

10
ld/testsuite/ld-mips-elf/mips16-pic-2.nd
View File

@ -1,9 +1,9 @@
# used8 should come before MIPS_GOTSYM.
#...
+3: 000405bc +36 +FUNC +GLOBAL +DEFAULT .* used8
+4: 00040574 +36 +FUNC +GLOBAL +DEFAULT .* used6
+5: 00040598 +36 +FUNC +GLOBAL +DEFAULT .* used7
+6: 00040550 +36 +FUNC +GLOBAL +DEFAULT .* used5
+7: 0004052c +36 +FUNC +GLOBAL +DEFAULT .* used4
+2: 000405bc +36 +FUNC +GLOBAL +DEFAULT .* used8
+3: 00040574 +36 +FUNC +GLOBAL +DEFAULT .* used6
+4: 00040598 +36 +FUNC +GLOBAL +DEFAULT .* used7
+5: 00040550 +36 +FUNC +GLOBAL +DEFAULT .* used5
+6: 0004052c +36 +FUNC +GLOBAL +DEFAULT .* used4
#pass

2
ld/testsuite/ld-mips-elf/pic-and-nonpic-3a.dd
View File

@ -35,5 +35,5 @@ Disassembly of section \.MIPS\.stubs:
c00: 8f998010 lw t9,-32752\(gp\)
c04: 03e07825 move t7,ra
c08: 0320f809 jalr t9
c0c: 24180005 li t8,5
c0c: 24180004 li t8,4
\.\.\.

10
ld/testsuite/ld-mips-elf/tlslib-o32-hidden.got
View File

@ -4,11 +4,11 @@
DYNAMIC RELOCATION RECORDS
OFFSET TYPE VALUE
00000000 R_MIPS_NONE \*ABS\*
000403bc R_MIPS_TLS_TPREL32 \*ABS\*
000403c0 R_MIPS_TLS_DTPMOD32 \*ABS\*
000403c8 R_MIPS_TLS_DTPMOD32 \*ABS\*
0004039c R_MIPS_TLS_TPREL32 \*ABS\*
000403a0 R_MIPS_TLS_DTPMOD32 \*ABS\*
000403a8 R_MIPS_TLS_DTPMOD32 \*ABS\*
Contents of section .got:
403b0 00000000 80000000 00000380 00000008 ................
403c0 00000000 ffff8004 00000000 00000000 ................
40390 00000000 80000000 00000360 00000008 ................
403a0 00000000 ffff8004 00000000 00000000 ................

12
ld/testsuite/ld-mips-elf/tlslib-o32-ver.got
View File

@ -4,12 +4,12 @@
DYNAMIC RELOCATION RECORDS
OFFSET TYPE VALUE
00000000 R_MIPS_NONE \*ABS\*
000404d8 R_MIPS_TLS_DTPMOD32 \*ABS\*
000404d0 R_MIPS_TLS_DTPMOD32 tlsvar_gd@@VER_1
000404d4 R_MIPS_TLS_DTPREL32 tlsvar_gd@@VER_1
000404cc R_MIPS_TLS_TPREL32 tlsvar_ie@@VER_1
000404b8 R_MIPS_TLS_DTPMOD32 \*ABS\*
000404b0 R_MIPS_TLS_DTPMOD32 tlsvar_gd@@VER_1
000404b4 R_MIPS_TLS_DTPREL32 tlsvar_gd@@VER_1
000404ac R_MIPS_TLS_TPREL32 tlsvar_ie@@VER_1
Contents of section .got:
404c0 00000000 80000000 00000490 00000000 ................
404d0 00000000 00000000 00000000 00000000 ................
404a0 00000000 80000000 00000470 00000000 ................
404b0 00000000 00000000 00000000 00000000 ................

12
ld/testsuite/ld-mips-elf/tlslib-o32.got
View File

@ -4,12 +4,12 @@ tmpdir/tlslib-o32.so: file format elf32-tradbigmips
DYNAMIC RELOCATION RECORDS
OFFSET TYPE VALUE
00000000 R_MIPS_NONE \*ABS\*
00040448 R_MIPS_TLS_DTPMOD32 \*ABS\*
00040440 R_MIPS_TLS_DTPMOD32 tlsvar_gd
00040444 R_MIPS_TLS_DTPREL32 tlsvar_gd
0004043c R_MIPS_TLS_TPREL32 tlsvar_ie
00040428 R_MIPS_TLS_DTPMOD32 \*ABS\*
00040420 R_MIPS_TLS_DTPMOD32 tlsvar_gd
00040424 R_MIPS_TLS_DTPREL32 tlsvar_gd
0004041c R_MIPS_TLS_TPREL32 tlsvar_ie
Contents of section .got:
40430 00000000 80000000 00000400 00000000 ................
40440 00000000 00000000 00000000 00000000 ................
40410 00000000 80000000 000003e0 00000000 ................
40420 00000000 00000000 00000000 00000000 ................