From 676ee2b5fa6ae41342a9fcd2b7ca18693fa0535b Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Sun, 16 Jul 2017 11:50:52 +0930 Subject: [PATCH] __tls_get_addr_opt GOT entries My 2017-01-24 patch (commit f0158f44) wrongly applied an optimization of GOT entries for the __tls_get_addr_opt stub, to shared libraries. When the TLS segment layout is known, as it is for the executable and shared libraries loaded at initial program start, powerpc supports a __tls_get_addr optimization. On the first call to __tls_get_addr for a given __tls_index GOT entry, the DTPMOD word is set to zero and the DTPREL word to the thread pointer offset to the thread variable. This allows the __tls_get_addr_opt stub to return that value immediately without making a call into glibc for any subsequent __tls_get_addr calls using that __tls_index GOT entry. That's all fine, but I thought I'd be clever and when the thread variable is local, set up the GOT entry as if __tls_get_addr had already been called. Which is good only for the executable, since ld cannot know the TLS layout for shared libraries. Of course, if this only applies to executables there isn't much point to the optimization. Normally, GD and LD code in an executable will be converted to IE or LE, losing the __tls_get_addr call. So the only time it will trigger is with --no-tls-optimize. Thus, revert all support. * elf64-ppc.c (ppc64_elf_relocate_section): Don't optimize __tls_index GOT entries when using __tls_get_addr_opt stub. * elf32-ppc.c (ppc_elf_relocate_section): Likewise. --- bfd/ChangeLog | 6 ++++++ bfd/elf32-ppc.c | 37 ++----------------------------------- bfd/elf64-ppc.c | 37 ++----------------------------------- 3 files changed, 10 insertions(+), 70 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index a98c93a..fbd44a7 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,9 @@ +2017-07-16 Alan Modra + + * elf64-ppc.c (ppc64_elf_relocate_section): Don't optimize + __tls_index GOT entries when using __tls_get_addr_opt stub. + * elf32-ppc.c (ppc_elf_relocate_section): Likewise. + 2017-07-12 Alan Modra * po/es.po: Update from translationproject.org/latest/bfd/. diff --git a/bfd/elf32-ppc.c b/bfd/elf32-ppc.c index 27d62ab..6d8b502 100644 --- a/bfd/elf32-ppc.c +++ b/bfd/elf32-ppc.c @@ -8639,10 +8639,6 @@ ppc_elf_relocate_section (bfd *output_bfd, else { bfd_vma value = relocation; - int tlsopt = (htab->plt_type == PLT_NEW - && !htab->params->no_tls_get_addr_opt - && htab->tls_get_addr != NULL - && htab->tls_get_addr->plt.plist != NULL); if (tls_ty != 0) { @@ -8654,8 +8650,7 @@ ppc_elf_relocate_section (bfd *output_bfd, value = 0; else value -= htab->elf.tls_sec->vma + DTP_OFFSET; - if ((tls_ty & TLS_TPREL) - || (tlsopt && !(tls_ty & TLS_DTPREL))) + if (tls_ty & TLS_TPREL) value += DTP_OFFSET - TP_OFFSET; } @@ -8663,7 +8658,7 @@ ppc_elf_relocate_section (bfd *output_bfd, { bfd_put_32 (input_bfd, value, htab->elf.sgot->contents + off + 4); - value = !tlsopt; + value = 1; } } bfd_put_32 (input_bfd, value, @@ -9008,34 +9003,6 @@ ppc_elf_relocate_section (bfd *output_bfd, break; } } - else if (r_type == R_PPC_DTPMOD32 - && htab->plt_type == PLT_NEW - && !htab->params->no_tls_get_addr_opt - && htab->tls_get_addr != NULL - && htab->tls_get_addr->plt.plist != NULL) - { - /* Set up for __tls_get_addr_opt stub when this entry - does not have dynamic relocs. */ - relocation = 0; - /* Set up the next word for local dynamic. If it turns - out to be global dynamic, the reloc will overwrite - this value. */ - if (rel->r_offset + 8 <= input_section->size) - bfd_put_32 (input_bfd, DTP_OFFSET - TP_OFFSET, - contents + rel->r_offset + 4); - } - else if (r_type == R_PPC_DTPREL32 - && htab->plt_type == PLT_NEW - && !htab->params->no_tls_get_addr_opt - && htab->tls_get_addr != NULL - && htab->tls_get_addr->plt.plist != NULL - && rel > relocs - && rel[-1].r_info == ELF32_R_INFO (r_symndx, R_PPC_DTPMOD32) - && rel[-1].r_offset + 4 == rel->r_offset) - { - /* __tls_get_addr_opt stub value. */ - addend += DTP_OFFSET - TP_OFFSET; - } break; case R_PPC_RELAX_PLT: diff --git a/bfd/elf64-ppc.c b/bfd/elf64-ppc.c index 319d58f..70ad6c5 100644 --- a/bfd/elf64-ppc.c +++ b/bfd/elf64-ppc.c @@ -14647,11 +14647,6 @@ ppc64_elf_relocate_section (bfd *output_bfd, emitting a reloc. */ else { - int tlsopt - = (htab->params->tls_get_addr_opt - && htab->tls_get_addr_fd != NULL - && htab->tls_get_addr_fd->elf.plt.plist != NULL); - relocation += addend; if (tls_type != 0) { @@ -14663,8 +14658,7 @@ ppc64_elf_relocate_section (bfd *output_bfd, relocation = 0; else relocation -= htab->elf.tls_sec->vma + DTP_OFFSET; - if ((tls_type & TLS_TPREL) - || (tlsopt && !(tls_type & TLS_DTPREL))) + if (tls_type & TLS_TPREL) relocation += DTP_OFFSET - TP_OFFSET; } @@ -14672,7 +14666,7 @@ ppc64_elf_relocate_section (bfd *output_bfd, { bfd_put_64 (output_bfd, relocation, got->contents + off + 8); - relocation = !tlsopt; + relocation = 1; } } bfd_put_64 (output_bfd, relocation, @@ -15080,32 +15074,6 @@ ppc64_elf_relocate_section (bfd *output_bfd, addend = outrel.r_offset; } } - else if (r_type == R_PPC64_DTPMOD64 - && htab->params->tls_get_addr_opt - && htab->tls_get_addr_fd != NULL - && htab->tls_get_addr_fd->elf.plt.plist != NULL) - { - /* Set up for __tls_get_addr_opt stub, when this entry - does not have dynamic relocs. */ - relocation = 0; - /* Set up the next word for local dynamic. If it turns - out to be global dynamic, the reloc will overwrite - this value. */ - if (rel->r_offset + 16 <= input_section->size) - bfd_put_64 (input_bfd, DTP_OFFSET - TP_OFFSET, - contents + rel->r_offset + 8); - } - else if (r_type == R_PPC64_DTPREL64 - && htab->params->tls_get_addr_opt - && htab->tls_get_addr_fd != NULL - && htab->tls_get_addr_fd->elf.plt.plist != NULL - && rel > relocs - && rel[-1].r_info == ELF64_R_INFO (r_symndx, R_PPC64_DTPMOD64) - && rel[-1].r_offset + 8 == rel->r_offset) - { - /* __tls_get_addr_opt stub value. */ - addend += DTP_OFFSET - TP_OFFSET; - } break; case R_PPC64_COPY: @@ -15899,4 +15867,3 @@ ppc64_elf_finish_dynamic_sections (bfd *output_bfd, #define elf64_bed elf64_powerpc_fbsd_bed #include "elf64-target.h" - -- 2.7.4