binutils/binutils-2.29-ppc64-plt-localentry0-disable.patch

117 lines
5.5 KiB
Diff

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