Commit Graph

2 Commits

Author SHA1 Message Date
Alan Modra
f26a32876b Dynamic TLS section symbols
It is possible to create shared libraries on PowerPC using
-ftls-model=inital-exec or -ftls-model=local-exec.  The first is half
reasonable, getting you a shared library that can't be dlopen'd but
otherwise is reasonable.  The second is quite bad.  Not only do you
lose being able to dlopen, the library also has dynamic text
relocations.  Worse, the TPREL16_LO, TPREL16_HA and other TPREL16
dynamic relocs emitted were wrong, resulting in wrong values being
applied by ld.so.

Using the first TLS section symbol in dynamic relocations for local
TLS symbols doesn't work.  It's wrong because TLS symbols used by TLS
relocs have values relative to the TLS segment, whereas the TLS
section symbols are addresses.  This patch instead uses a symbol index
of zero which is used elsewhere by PowerPC on dynamic TLS relocs.
It's not strictly ABI compliant to use a non-TLS symbol with TLS
relocs but symbol index zero can be interpreted as "no symbol".  Not
using the first TLS section symbol means it doesn't need to be dynamic.

The patch also fixes a further problem with PowerPC32 dynamic TPREL16*
relocs, which shouldn't have the symbol value in the addend as we do
for non-TLS symbols.

bfd/
	* elflink.c (_bfd_elf_omit_section_dynsym_default): Don't keep
	tls_sec.
	(_bfd_elf_init_1_index_section): Prefer not using TLS sections.
	(_bfd_elf_init_2_index_sections): Likewise.
	* elf64-ppc.c (ppc64_elf_relocate_section): When emitting dynamic
	relocations for local TLS symbols, use STN_UNDEF as the relocation
	symbol.
	* elf32-ppc.c (ppc_elf_relocate_section): Likewise, and don't
	leave TLS symbol value in the addend.
ld/
	* testsuite/ld-powerpc/tlsso.r: Update.
	* testsuite/ld-powerpc/tlsso32.g: Update.
	* testsuite/ld-powerpc/tlsso32.r: Update.
	* testsuite/ld-powerpc/tlstocso.r: Update.
	* testsuite/ld-cris/tls-dso-dtpoffd2.d: Update.
	* testsuite/ld-cris/tls-dso-dtpoffd4.d: Update.
	* testsuite/ld-cris/tls-dso-tpoffgotcomm1.d: Update.
	* testsuite/ld-cris/tls-gd-1.d: Update.
	* testsuite/ld-cris/tls-gd-1h.d: Update.
	* testsuite/ld-cris/tls-gd-2.d: Update.
	* testsuite/ld-cris/tls-gd-2h.d: Update.
	* testsuite/ld-cris/tls-ie-10.d: Update.
	* testsuite/ld-cris/tls-ie-11.d: Update.
	* testsuite/ld-cris/tls-ie-8.d: Update.
	* testsuite/ld-cris/tls-ie-9.d: Update.
	* testsuite/ld-cris/tls-js1.d: Update.
	* testsuite/ld-cris/tls-ld-4.d: Update.
	* testsuite/ld-cris/tls-ld-5.d: Update.
	* testsuite/ld-cris/tls-ld-6.d: Update.
	* testsuite/ld-cris/tls-ld-7.d: Update.
	* testsuite/ld-cris/tls-ldgd-14.d: Update.
	* testsuite/ld-cris/tls-ldgd-15.d: Update.
	* testsuite/ld-cris/tls-ldgdx-14.d: Update.
	* testsuite/ld-cris/tls-ldgdx-15.d: Update.
	* testsuite/ld-cris/tls-local-54.d: Update.
	* testsuite/ld-cris/tls-local-60.d: Update.
	* testsuite/ld-cris/tls-local-61.d: Update.
	* testsuite/ld-cris/tls-local-63.d: Update.
	* testsuite/ld-cris/tls-local-64.d: Update.
	* testsuite/ld-cris/tls-ok-30.d: Update.
	* testsuite/ld-cris/tls-ok-32.d: Update.
	* testsuite/ld-cris/tls-ok-34.d: Update.
	* testsuite/ld-mips-elf/tls-multi-got-1.got: Update.
	* testsuite/ld-mips-elf/tls-multi-got-1.r: Update.
	* testsuite/ld-mips-elf/tlsdyn-pie-o32.d: Update.
	* testsuite/ld-mips-elf/tlsdyn-pie-o32.got: Update.
	* testsuite/ld-mips-elf/tlslib-o32-hidden.got: Update.
	* testsuite/ld-mips-elf/tlslib-o32-ver.got: Update.
	* testsuite/ld-mips-elf/tlslib-o32.got: Update.
	* testsuite/ld-s390/tlspic.rd: Update.
	* testsuite/ld-s390/tlspic_64.rd: Update.
	* testsuite/ld-sparc/tlssunnopic32.rd: Update.
	* testsuite/ld-sparc/tlssunnopic64.rd: Update.
	* testsuite/ld-sparc/tlssunpic32.rd: Update.
	* testsuite/ld-sparc/tlssunpic64.rd: Update.
2019-07-13 09:57:50 +09:30
Maciej W. Rozycki
9143e72c6d PR ld/22570: MIPS/BFD: Fix TLS relocation resolution for PIE executables
Correct a commit 0e1862bb40 ("Add output_type to bfd_link_info") issue
and use `bfd_link_dll' rather than `bfd_link_pic' in determining whether
to fully resolve GD, LD and IE TLS relocations referring to symbols
locally defined rather than deferring them to the load time by means of
dynamic relocations.

Such symbols cannot be preempted in PIE executables, which are
necessarily PIC, and therefore their values (thread pointer offsets) are
fixed at the static link time as is the associated module ID of the main
executable.

Given the `tlsbin-o32.s' and `tlsdyn-o32.s' sources from our test suite
this removes the absolute TLS relocations from the static:

DYNAMIC RELOCATION RECORDS
OFFSET   TYPE              VALUE
00000000 R_MIPS_NONE       *ABS*
1000002c R_MIPS_TLS_TPREL32  *ABS*
10000030 R_MIPS_TLS_DTPMOD32  *ABS*
10000038 R_MIPS_TLS_DTPMOD32  *ABS*

and the dynamic:

DYNAMIC RELOCATION RECORDS
OFFSET   TYPE              VALUE
00000000 R_MIPS_NONE       *ABS*
1000002c R_MIPS_TLS_TPREL32  *ABS*
10000038 R_MIPS_TLS_DTPMOD32  *ABS*
10000044 R_MIPS_TLS_DTPMOD32  *ABS*
10000030 R_MIPS_TLS_DTPMOD32  tlsvar_gd
10000034 R_MIPS_TLS_DTPREL32  tlsvar_gd
10000040 R_MIPS_TLS_TPREL32  tlsvar_ie

PIE executable respectively, as reported by `objdump -R', and fills the
corresponding GOT slots with the values expected, as recorded with the
test cases added.  The new output from `objdump -R' is:

DYNAMIC RELOCATION RECORDS (none)

and:

DYNAMIC RELOCATION RECORDS
OFFSET   TYPE              VALUE
00000000 R_MIPS_NONE       *ABS*
10000030 R_MIPS_TLS_DTPMOD32  tlsvar_gd
10000034 R_MIPS_TLS_DTPREL32  tlsvar_gd
10000040 R_MIPS_TLS_TPREL32  tlsvar_ie

for the static and the dynamic executable respectively.

2018-07-11  Maciej W. Rozycki  <macro@mips.com>
            Rich Felker  <bugdal@aerifal.cx>

	bfd/
	PR ld/22570
	* elfxx-mips.c (mips_tls_got_relocs): Use `bfd_link_dll' rather
	than `bfd_link_pic' to determine whether dynamic relocations are
	to be produced.
	(mips_elf_initialize_tls_slots): Likewise.

	ld/
	PR ld/22570
	* testsuite/ld-mips-elf/tlsbin-pie-o32.d: New test.
	* testsuite/ld-mips-elf/tlsbin-pie-o32.got: New test.
	* testsuite/ld-mips-elf/tlsdyn-pie-o32.d: New test.
	* testsuite/ld-mips-elf/tlsdyn-pie-o32.got: New test.
	* testsuite/ld-mips-elf/mips-elf.exp: Run the new tests.
2018-07-11 17:44:45 +01:00