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authorAlan Modra <amodra@gmail.com>2018-01-13 18:53:41 +1030
committerAlan Modra <amodra@gmail.com>2018-01-17 18:51:04 +1030
commit9e390558cef76767a98123994c422d0642d86cf8 (patch)
treefa46b2f2c764e30be6e6e512fe29a01de0b4ad04 /gold/options.h
parent78742b93a5fef4b88b1391817e7bcc6738000044 (diff)
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PowerPC PLT stub tidy
This is in preparation for the next patch adding Spectre variant 2 mitigation for PowerPC and PowerPC64. Besides tidying code involved in stub output (to reduce the number of places where bctr is output), the patch adds some user visible features: 1) PowerPC64 ELFv2 global entry stubs now are aligned under the control of --plt-align, with a default alignment of 32 bytes. 2) PowerPC64 __glink_PLTresolve is no longer padded out with nops. 3) PowerPC32 PLT stubs are aligned under the control of --plt-align, with the default alignment being 16 bytes as before. 4) The PowerPC32 branch/nop table emitted before __glink_PLTresolve is now smaller in many cases. It was sized incorrectly when the __tls_get_addr_opt stub was used, and unnecessarily included space for local ifuncs. bfd/ * elf32-ppc.c (GLINK_ENTRY_SIZE): Add parameters, handle __tls_get_addr_opt, and alignment sizing. (TLS_GET_ADDR_GLINK_SIZE): Delete. (is_nonpic_glink_stub): Don't use GLINK_ENTRY_SIZE. (ppc_elf_get_synthetic_symtab): Recognize stubs spaced at 4, 6, or 8 insns. (ppc_elf_link_hash_table_create): Init new ppc_elf_params field. (allocate_dynrelocs): Use new GLINK_ENTRY_SIZE. (ppc_elf_size_dynamic_sections): Likewise. Size branch table by PLT reloc count. (write_glink_stub): Handle __tls_get_addr_opt stub. Pad out to size given by GLINK_ENTRY_SIZE. (ppc_elf_relocate_section): Adjust write_glink_stub call. (ppc_elf_finish_dynamic_symbol): Likewise. (ppc_elf_finish_dynamic_sections): Write PLTresolve without using insn array since so many need rewriting. * elf32-ppc.h (struct ppc_elf_params): Add plt_stub_align. * elf64-ppc.c (GLINK_PLTRESOLVE_SIZE): Rename from GLINK_CALL_STUB_SIZE. Add htab param and evaluate to size without nops. Adjust all uses. (ppc64_elf_get_synthetic_symtab): Don't use GLINK_CALL_STUB_SIZE in glink_vma calculation. (struct ppc_link_hash_table): Add global_entry section pointer. (create_linkage_sections): Create separate section for global entry stubs. (PPC_LO, PPC_HI, PPC_HA): Move earlier. (size_global_entry_stubs): Handle sizing for aligned stubs. (ppc64_elf_size_dynamic_sections): Handle global_entry alloc, and don't stash end of glink branch table in rawsize. (ppc_build_one_stub): Rewrite stub size calculations. (build_global_entry_stubs): Use new section. (ppc64_elf_build_stubs): Don't pad __glink_PLTresolve with nops. Build lazy link stubs out to end of section. Build global entry stubs in new section. gold/ * options.h (plt_align): Support for PowerPC32 too. * powerpc.cc (Stub_table::stub_align): Heed --plt-align for 32-bit. (Stub_table::plt_call_size, branch_stub_size): Tidy. (Stub_table::plt_call_align): Implement using stub_align. (Output_data_glink::global_entry_align): New function. (Output_data_glink::global_entry_off): New function. (Output_data_glink::global_entry_address): Use global_entry_off. (Output_data_glink::pltresolve_size): New function, replacing pltresolve_size_ constant. Update all uses. (Output_data_glink::add_global_entry): Align offset. (Output_data_glink::set_final_data_size): Use global_entry_align. (Stub_table::do_write): Don't pad __glink_PLTrelsolve with nops. Tidy stub output. Use global_entry_off. ld/ * emultempl/ppc32elf.em (params): Init new field. (enum ppc32_opt): New enum to define OPTION_* values. Add OPTION_PLT_ALIGN and OPTION_NO_PLT_ALIGN. (PARSE_AND_LIST_LONGOPTS): Handle new options. (PARSE_AND_LIST_ARGS_CASES): Likewise. (PARSE_AND_LIST_OPTIONS): Likewise. Break up help output. * emultempl/ppc64elf.em (ppc_add_stub_section): Init alignment correctly for negative --plt-stub-align. * testsuite/ld-powerpc/elfv2exe.d, * testsuite/ld-powerpc/elfv2so.d, * testsuite/ld-powerpc/relbrlt.d, * testsuite/ld-powerpc/relbrlt.s, * testsuite/ld-powerpc/tlsexe.d, * testsuite/ld-powerpc/tlsexe.r, * testsuite/ld-powerpc/tlsexe32.d, * testsuite/ld-powerpc/tlsexe32.g, * testsuite/ld-powerpc/tlsexe32.r, * testsuite/ld-powerpc/tlsexetoc.d, * testsuite/ld-powerpc/tlsexetoc.r, * testsuite/ld-powerpc/tlsopt5_32.d, * testsuite/ld-powerpc/tlsso.d, * testsuite/ld-powerpc/tlstocso.d: Update for changed stub order.
Diffstat (limited to 'gold/options.h')
-rw-r--r--gold/options.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/gold/options.h b/gold/options.h
index feb60cc..b39d5ff 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -1101,7 +1101,7 @@ class General_options
NULL, N_("(ARM only) Ignore for backward compatibility"));
DEFINE_var(plt_align, options::TWO_DASHES, '\0', 0, "5",
- N_("(PowerPC64 only) Align PLT call stubs to fit cache lines"),
+ N_("(PowerPC only) Align PLT call stubs to fit cache lines"),
N_("[=P2ALIGN]"), true, int, int, options::parse_uint, false);
DEFINE_bool(plt_localentry, options::TWO_DASHES, '\0', false,