117 lines
5.5 KiB
Diff
117 lines
5.5 KiB
Diff
diff -rup binutils.orig/bfd/elf64-ppc.c binutils-2.29/bfd/elf64-ppc.c
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--- binutils.orig/bfd/elf64-ppc.c 2017-07-31 10:48:13.642980052 +0100
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+++ binutils-2.29/bfd/elf64-ppc.c 2017-07-31 10:48:37.386711582 +0100
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@@ -4010,6 +4010,10 @@ struct ppc_link_hash_entry
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with non-standard calling convention. */
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unsigned int save_res:1;
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+ /* Set if a duplicate symbol with non-zero localentry is detected,
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+ even when the duplicate symbol does not provide a definition. */
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+ unsigned int non_zero_localentry:1;
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+
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/* Contexts in which symbol is used in the GOT (or TOC).
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TLS_GD .. TLS_EXPLICIT bits are or'd into the mask as the
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corresponding relocs are encountered during check_relocs.
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@@ -5018,7 +5022,7 @@ ppc64_elf_merge_symbol_attribute (struct
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static bfd_boolean
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ppc64_elf_merge_symbol (struct elf_link_hash_entry *h,
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- const Elf_Internal_Sym *isym ATTRIBUTE_UNUSED,
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+ const Elf_Internal_Sym *isym,
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asection **psec ATTRIBUTE_UNUSED,
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bfd_boolean newdef ATTRIBUTE_UNUSED,
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bfd_boolean olddef ATTRIBUTE_UNUSED,
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@@ -5026,6 +5030,8 @@ ppc64_elf_merge_symbol (struct elf_link_
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const asection *oldsec ATTRIBUTE_UNUSED)
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{
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((struct ppc_link_hash_entry *) h)->fake = 0;
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+ if ((STO_PPC64_LOCAL_MASK & isym->st_other) != 0)
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+ ((struct ppc_link_hash_entry *) h)->non_zero_localentry = 1;
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return TRUE;
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}
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@@ -6332,6 +6338,7 @@ is_elfv2_localentry0 (struct elf_link_ha
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&& h->type == STT_FUNC
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&& h->root.type == bfd_link_hash_defined
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&& (STO_PPC64_LOCAL_MASK & h->other) == 0
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+ && !((struct ppc_link_hash_entry *) h)->non_zero_localentry
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&& is_ppc64_elf (h->root.u.def.section->owner)
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&& abiversion (h->root.u.def.section->owner) >= 2);
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}
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@@ -8346,10 +8353,28 @@ ppc64_elf_tls_setup (struct bfd_link_inf
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else if (!htab->do_multi_toc)
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htab->params->no_multi_toc = 1;
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+ /* Default to --no-plt-localentry, as this option can cause problems
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+ with symbol interposition. For example, glibc libpthread.so and
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+ libc.so duplicate many pthread symbols, with a fallback
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+ implementation in libc.so. In some cases the fallback does more
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+ work than the pthread implementation. __pthread_condattr_destroy
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+ is one such symbol: the libpthread.so implementation is
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+ localentry:0 while the libc.so implementation is localentry:8.
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+ An app that "cleverly" uses dlopen to only load necessary
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+ libraries at runtime may omit loading libpthread.so when not
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+ running multi-threaded, which then results in the libc.so
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+ fallback symbols being used and ld.so complaining. Now there
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+ are workarounds in ld (see non_zero_localentry) to detect the
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+ pthread situation, but that may not be the only case where
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+ --plt-localentry can cause trouble. */
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if (htab->params->plt_localentry0 < 0)
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- htab->params->plt_localentry0
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- = elf_link_hash_lookup (&htab->elf, "GLIBC_2.26",
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- FALSE, FALSE, FALSE) != NULL;
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+ htab->params->plt_localentry0 = 0;
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+ if (htab->params->plt_localentry0
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+ && elf_link_hash_lookup (&htab->elf, "GLIBC_2.26",
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+ FALSE, FALSE, FALSE) == NULL)
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+ info->callbacks->einfo
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+ (_("%P: warning: --plt-localentry is especially dangerous without "
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+ "ld.so support to detect ABI violations.\n"));
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htab->tls_get_addr = ((struct ppc_link_hash_entry *)
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elf_link_hash_lookup (&htab->elf, ".__tls_get_addr",
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diff -rup binutils.orig/gold/powerpc.cc binutils-2.29/gold/powerpc.cc
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--- binutils.orig/gold/powerpc.cc 2017-07-31 10:48:13.621980289 +0100
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+++ binutils-2.29/gold/powerpc.cc 2017-07-31 10:48:37.387711571 +0100
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@@ -7660,8 +7660,10 @@ Target_powerpc<size, big_endian>::scan_r
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{
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if (parameters->options().user_set_plt_localentry())
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plt_localentry0 = parameters->options().plt_localentry();
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- else
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- plt_localentry0 = symtab->lookup("GLIBC_2.26", NULL) != NULL;
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+ if (plt_localentry0
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+ && symtab->lookup("GLIBC_2.26", NULL) == NULL)
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+ gold_warning(_("--plt-localentry is especially dangerous without "
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+ "ld.so support to detect ABI violations"));
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}
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this->plt_localentry0_ = plt_localentry0;
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this->plt_localentry0_init_ = true;
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diff -rup binutils.orig/ld/ld.texinfo binutils-2.29/ld/ld.texinfo
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--- binutils.orig/ld/ld.texinfo 2017-07-31 10:48:13.601980515 +0100
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+++ binutils-2.29/ld/ld.texinfo 2017-07-31 10:48:37.388711559 +0100
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@@ -7600,6 +7600,24 @@ barrier in the call stub, or use LD_BIND
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looks for calls to commonly used functions that create threads, and if
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seen, adds the necessary barriers. Use these options to change the
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default behaviour.
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+
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+@cindex PowerPC64 ELFv2 PLT localentry optimization
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+@kindex --plt-localentry
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+@kindex --no-plt-localentry
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+@item --plt-localentry
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+@itemx --no-localentry
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+ELFv2 functions with localentry:0 are those with a single entry point,
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+ie. global entry == local entry, and that have no requirement on r2
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+(the TOC/GOT pointer) or r12, and guarantee r2 is unchanged on return.
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+Such an external function can be called via the PLT without saving r2
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+or restoring it on return, avoiding a common load-hit-store for small
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+functions. The optimization is attractive, with up to 40% reduction
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+in execution time for a small function, but can result in symbol
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+interposition failures. Also, minor changes in a shared library,
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+including system libraries, can cause a function that was localentry:0
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+to become localentry:8. This will result in a dynamic loader
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+complaint and failure to run. The option is experimental, use with
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+care. @option{--no-plt-localentry} is the default.
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@end table
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@ifclear GENERIC
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