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authorAlan Modra <amodra@gmail.com>2012-01-11 09:28:45 +0000
committerAlan Modra <amodra@gmail.com>2012-01-11 09:28:45 +0000
commit794e51c094034378e14eec48b628957e71887265 (patch)
tree2fb54b112027804477e0fdbd06530d571deeb74d /ld
parent313a658140f4e578ca376be3e3cf68ff561d3979 (diff)
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* elf64-ppc.c: Define more insns used in plt call stubs. (ppc64_elf_brtaken_reloc): Assume isa version 2 or above. (ppc64_elf_relocate_section): Likewise. (enum ppc_stub_type): Add ppc_stub_plt_call_r2save. (struct ppc_link_hash_table): Increase size of stub_count array. Add plt_stub_align and plt_thread_safe. (ALWAYS_USE_FAKE_DEP, ALWAYS_EMIT_R2SAVE): Define. (plt_stub_size, plt_stub_pad): New functions. (build_plt_stub): Emit barriers for power7 thread safety. Don't emit needless save of r2. (build_tls_get_addr_stub): Adjust params. (ppc_build_one_stub): Handle ppc_stub_plt_call_r2save and aligning plt stubs. Adjust build_*plt_stub calls. (ppc_size_one_stub): Similarly. (ppc64_elf_size_stubs): Accept plt_thread_safe and plt_stub_align params. Choose default for plt_thread_safe based on existence of calls to thread creation functions. Modify plt_call to plt_call_r2save when no tocsave reloc found. Align tail of stub sections. (ppc64_elf_build_stubs): Align tail of stub sections. Adjust output of stub statistics. (ppc64_elf_relocate_section): Handle ppc_stub_plt_call_r2save. * elf64-ppc.h (ppc64_elf_size_stubs): Update prototype. ld/ * emultempl/ppc64elf.em (PARSE_AND_LIST_PROLOGUE, PARSE_AND_LIST_LONGOPTS, PARSE_AND_LIST_OPTIONS, PARSE_AND_LIST_ARGS_CASES): Handle --{no-,}plt-thread-safe and --{no-,}plt-align. (plt_thread_safe, plt_stub_align): New vars. (gld${EMULATION_NAME}_after_allocation): Pass them to ppc64_elf_size_stubs. Align stub sections according to plt_stub_align. * ld.texinfo: Document new command line options, and an old undocumented option.
Diffstat (limited to 'ld')
-rw-r--r--ld/ChangeLog12
-rw-r--r--ld/emultempl/ppc64elf.em66
-rw-r--r--ld/ld.texinfo52
3 files changed, 122 insertions, 8 deletions
diff --git a/ld/ChangeLog b/ld/ChangeLog
index d779176..8d4027f 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,15 @@
+2012-01-11 Alan Modra <amodra@gmail.com>
+
+ * emultempl/ppc64elf.em (PARSE_AND_LIST_PROLOGUE,
+ PARSE_AND_LIST_LONGOPTS, PARSE_AND_LIST_OPTIONS,
+ PARSE_AND_LIST_ARGS_CASES): Handle --{no-,}plt-thread-safe and
+ --{no-,}plt-align.
+ (plt_thread_safe, plt_stub_align): New vars.
+ (gld${EMULATION_NAME}_after_allocation): Pass them to
+ ppc64_elf_size_stubs. Align stub sections according to plt_stub_align.
+ * ld.texinfo: Document new command line options, and an old
+ undocumented option.
+
2012-01-09 Roland McGrath <mcgrathr@google.com>
* configure.in: Use AM_ZLIB.
diff --git a/ld/emultempl/ppc64elf.em b/ld/emultempl/ppc64elf.em
index 9c352ee..5b637e1 100644
--- a/ld/emultempl/ppc64elf.em
+++ b/ld/emultempl/ppc64elf.em
@@ -1,5 +1,5 @@
# This shell script emits a C file. -*- C -*-
-# Copyright 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+# Copyright 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
# Free Software Foundation, Inc.
#
# This file is part of the GNU Binutils.
@@ -64,6 +64,12 @@ static int no_toc_sort = 0;
/* Set if PLT call stubs should load r11. */
static int plt_static_chain = ${DEFAULT_PLT_STATIC_CHAIN-0};
+/* Set if PLT call stubs need to be thread safe on power7+. */
+static int plt_thread_safe = -1;
+
+/* Set if individual PLT call stubs should be aligned. */
+static int plt_stub_align = 0;
+
/* Whether to emit symbols for stubs. */
static int emit_stub_syms = -1;
@@ -379,7 +385,8 @@ ppc_add_stub_section (const char *stub_sec_name, asection *input_section)
stub_sec = bfd_make_section_anyway_with_flags (stub_file->the_bfd,
stub_sec_name, flags);
if (stub_sec == NULL
- || !bfd_set_section_alignment (stub_file->the_bfd, stub_sec, 5))
+ || !bfd_set_section_alignment (stub_file->the_bfd, stub_sec,
+ plt_stub_align > 5 ? plt_stub_align : 5))
goto err_ret;
output_section = input_section->output_section;
@@ -504,7 +511,9 @@ gld${EMULATION_NAME}_after_allocation (void)
einfo ("%P: .init/.fini fragments use differing TOC pointers\n");
/* Call into the BFD backend to do the real work. */
- if (!ppc64_elf_size_stubs (&link_info, group_size, plt_static_chain))
+ if (!ppc64_elf_size_stubs (&link_info, group_size,
+ plt_static_chain, plt_thread_safe,
+ plt_stub_align))
einfo ("%X%P: can not size stub section: %E\n");
}
}
@@ -649,7 +658,11 @@ PARSE_AND_LIST_PROLOGUE=${PARSE_AND_LIST_PROLOGUE}'
#define OPTION_STUBGROUP_SIZE 321
#define OPTION_PLT_STATIC_CHAIN (OPTION_STUBGROUP_SIZE + 1)
#define OPTION_NO_PLT_STATIC_CHAIN (OPTION_PLT_STATIC_CHAIN + 1)
-#define OPTION_STUBSYMS (OPTION_NO_PLT_STATIC_CHAIN + 1)
+#define OPTION_PLT_THREAD_SAFE (OPTION_NO_PLT_STATIC_CHAIN + 1)
+#define OPTION_NO_PLT_THREAD_SAFE (OPTION_PLT_THREAD_SAFE + 1)
+#define OPTION_PLT_ALIGN (OPTION_NO_PLT_THREAD_SAFE + 1)
+#define OPTION_NO_PLT_ALIGN (OPTION_PLT_ALIGN + 1)
+#define OPTION_STUBSYMS (OPTION_NO_PLT_ALIGN + 1)
#define OPTION_NO_STUBSYMS (OPTION_STUBSYMS + 1)
#define OPTION_DOTSYMS (OPTION_NO_STUBSYMS + 1)
#define OPTION_NO_DOTSYMS (OPTION_DOTSYMS + 1)
@@ -666,6 +679,10 @@ PARSE_AND_LIST_LONGOPTS=${PARSE_AND_LIST_LONGOPTS}'
{ "stub-group-size", required_argument, NULL, OPTION_STUBGROUP_SIZE },
{ "plt-static-chain", no_argument, NULL, OPTION_PLT_STATIC_CHAIN },
{ "no-plt-static-chain", no_argument, NULL, OPTION_NO_PLT_STATIC_CHAIN },
+ { "plt-thread-safe", no_argument, NULL, OPTION_PLT_THREAD_SAFE },
+ { "no-plt-thread-safe", no_argument, NULL, OPTION_NO_PLT_THREAD_SAFE },
+ { "plt-align", optional_argument, NULL, OPTION_PLT_ALIGN },
+ { "no-plt-align", no_argument, NULL, OPTION_NO_PLT_ALIGN },
{ "emit-stub-syms", no_argument, NULL, OPTION_STUBSYMS },
{ "no-emit-stub-syms", no_argument, NULL, OPTION_NO_STUBSYMS },
{ "dotsyms", no_argument, NULL, OPTION_DOTSYMS },
@@ -691,10 +708,22 @@ PARSE_AND_LIST_OPTIONS=${PARSE_AND_LIST_OPTIONS}'
choose suitable defaults.\n"
));
fprintf (file, _("\
- --plt-static-chain PLT call stubs should load r11.\n"
+ --plt-static-chain PLT call stubs should load r11.${DEFAULT_PLT_STATIC_CHAIN- (default)}\n"
+ ));
+ fprintf (file, _("\
+ --no-plt-static-chain PLT call stubs should not load r11.${DEFAULT_PLT_STATIC_CHAIN+ (default)}\n"
+ ));
+ fprintf (file, _("\
+ --plt-thread-safe PLT call stubs with load-load barrier.\n"
+ ));
+ fprintf (file, _("\
+ --no-plt-thread-safe PLT call stubs without barrier.\n"
+ ));
+ fprintf (file, _("\
+ --plt-align [=<align>] Align PLT call stubs to fit cache lines.\n"
));
fprintf (file, _("\
- --no-plt-static-chain PLT call stubs should not load r11. (default)\n"
+ --no-plt-align Dont'\''t align individual PLT call stubs.\n"
));
fprintf (file, _("\
--emit-stub-syms Label linker stubs with a symbol.\n"
@@ -753,6 +782,31 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
plt_static_chain = 0;
break;
+ case OPTION_PLT_THREAD_SAFE:
+ plt_thread_safe = 1;
+ break;
+
+ case OPTION_NO_PLT_THREAD_SAFE:
+ plt_thread_safe = 0;
+ break;
+
+ case OPTION_PLT_ALIGN:
+ if (optarg != NULL)
+ {
+ char *end;
+ unsigned long val = strtoul (optarg, &end, 0);
+ if (*end || val > 8)
+ einfo (_("%P%F: invalid --plt-align `%s'\''\n"), optarg);
+ plt_stub_align = val;
+ }
+ else
+ plt_stub_align = 5;
+ break;
+
+ case OPTION_NO_PLT_ALIGN:
+ plt_stub_align = 0;
+ break;
+
case OPTION_STUBSYMS:
emit_stub_syms = 1;
break;
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index 592e38c..6c74ff5 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -1,7 +1,7 @@
\input texinfo
@setfilename ld.info
@c Copyright 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
-@c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
+@c 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012
@c Free Software Foundation, Inc.
@syncodeindex ky cp
@c man begin INCLUDE
@@ -6710,7 +6710,9 @@ optimization.
@cindex PowerPC64 multi-TOC
@kindex --no-multi-toc
@item --no-multi-toc
-By default, PowerPC64 GCC generates code for a TOC model where TOC
+If given any toc option besides @code{-mcmodel=medium} or
+@code{-mcmodel=large}, PowerPC64 GCC generates code for a TOC model
+where TOC
entries are accessed with a 16-bit offset from r2. This limits the
total TOC size to 64K. PowerPC64 @command{ld} extends this limit by
grouping code sections such that each group uses less than 64K for its
@@ -6719,6 +6721,52 @@ calls. @command{ld} does not split apart input sections, so cannot
help if a single input file has a @code{.toc} section that exceeds
64K, most likely from linking multiple files with @command{ld -r}.
Use this option to turn off this feature.
+
+@cindex PowerPC64 TOC sorting
+@kindex --no-toc-sort
+@item --no-toc-sort
+By default, @command{ld} sorts TOC sections so that those whose file
+happens to have a section called @code{.init} or @code{.fini} are
+placed first, followed by TOC sections referenced by code generated
+with PowerPC64 gcc's @code{-mcmodel=small}, and lastly TOC sections
+referenced only by code generated with PowerPC64 gcc's
+@code{-mcmodel=medium} or @code{-mcmodel=large} options. Doing this
+results in better TOC grouping for multi-TOC. Use this option to turn
+off this feature.
+
+@cindex PowerPC64 PLT stub alignment
+@kindex --plt-align
+@kindex --no-plt-align
+@item --plt-align
+@itemx --no-plt-align
+Use these options to control whether individual PLT call stubs are
+aligned to a 32-byte boundary, or to the specified power of two
+boundary when using @code{--plt-align=}. By default PLT call stubs
+are packed tightly.
+
+@cindex PowerPC64 PLT call stub static chain
+@kindex --plt-static-chain
+@kindex --no-plt-static-chain
+@item --plt-static-chain
+@itemx --no-plt-static-chain
+Use these options to control whether PLT call stubs load the static
+chain pointer (r11). @code{ld} defaults to not loading the static
+chain since there is never any need to do so on a PLT call.
+
+@cindex PowerPC64 PLT call stub thread safety
+@kindex --plt-thread-safe
+@kindex --no-plt-thread-safe
+@item --plt-thread-safe
+@itemx --no-thread-safe
+With power7's weakly ordered memory model, it is possible when using
+lazy binding for ld.so to update a plt entry in one thread and have
+another thread see the individual plt entry words update in the wrong
+order, despite ld.so carefully writing in the correct order and using
+memory write barriers. To avoid this we need some sort of read
+barrier in the call stub, or use LD_BIND_NOW=1. By default, @code{ld}
+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.
@end table
@ifclear GENERIC