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[binutils-gdb] ld: Add --enable-separate-code
- From: H.J.Lu <hjl at sourceware dot org>
- To: bfd-cvs at sourceware dot org
- Date: 27 Feb 2018 19:55:58 -0000
- Subject: [binutils-gdb] ld: Add --enable-separate-code
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f6aec96dce1ddbd8961a3aa8a2925db2021719bb
commit f6aec96dce1ddbd8961a3aa8a2925db2021719bb
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Tue Feb 27 11:34:20 2018 -0800
ld: Add --enable-separate-code
This patch adds --enable-separate-code to ld configure to turn on
-z separate-code by default and enables it by default for Linux/x86.
This avoids mixing code pages with data to improve cache performance
as well as security.
To reduce x86-64 executable and shared object sizes, the maximum page
size is reduced from 2MB to 4KB when -z separate-code is turned on by
default. Note: -z max-page-size= can be used to set the maximum page
size.
We compared SPEC CPU 2017 performance before and after this change on
Skylake server. There are no any significant performance changes.
Everything is mostly below +/-1%.
bfd/
* config.in: Regenerated.
* configure: Likewise.
* configure.ac: Add --enable-separate-code.
(DEFAULT_LD_Z_SEPARATE_CODE): New AC_DEFINE_UNQUOTED. Default
to 1 for Linux/x86 targets,
* elf64-x86-64.c (ELF_MAXPAGESIZE): Set to 0x1000 if
DEFAULT_LD_Z_SEPARATE_CODE is 1.
ld/
* NEWS: Mention --enable-separate-code.
* configure.ac: Add --enable-separate-code.
(DEFAULT_LD_Z_SEPARATE_CODE): New AC_DEFINE_UNQUOTED.
* configure.tgt: Default ac_default_ld_z_separate_code to 1 for
Linux/x86 targets.
* config.in: Regenerated.
* configure: Likewise.
* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
link_info.separate_code DEFAULT_LD_Z_SEPARATE_CODE.
Diff:
---
bfd/ChangeLog | 10 ++++++++++
bfd/config.in | 4 ++++
bfd/configure | 33 +++++++++++++++++++++++++++++++--
bfd/configure.ac | 24 ++++++++++++++++++++++++
bfd/elf64-x86-64.c | 12 ++++++++++--
ld/ChangeLog | 12 ++++++++++++
ld/NEWS | 5 +++++
ld/config.in | 4 ++++
ld/configure | 26 ++++++++++++++++++++++++--
ld/configure.ac | 17 +++++++++++++++++
ld/configure.tgt | 9 +++++++++
ld/emultempl/elf32.em | 1 +
12 files changed, 151 insertions(+), 6 deletions(-)
diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 5c2a888..59f7c9c 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,3 +1,13 @@
+2018-02-27 H.J. Lu <hongjiu.lu@intel.com>
+
+ * config.in: Regenerated.
+ * configure: Likewise.
+ * configure.ac: Add --enable-separate-code.
+ (DEFAULT_LD_Z_SEPARATE_CODE): New AC_DEFINE_UNQUOTED. Default
+ to 1 for Linux/x86 targets,
+ * elf64-x86-64.c (ELF_MAXPAGESIZE): Set to 0x1000 if
+ DEFAULT_LD_Z_SEPARATE_CODE is 1.
+
2018-02-27 Nick Clifton <nickc@redhat.com>
* aout-cris.c (swap_ext_reloc_out): Standadize error/warning
diff --git a/bfd/config.in b/bfd/config.in
index 75a5ff0..186741d 100644
--- a/bfd/config.in
+++ b/bfd/config.in
@@ -10,6 +10,10 @@
/* Name of host specific core header file to include in elf.c. */
#undef CORE_HEADER
+/* Define to 1 if you want to enable -z separate-code in ELF linker by
+ default. */
+#undef DEFAULT_LD_Z_SEPARATE_CODE
+
/* Define to 1 if translation of program messages to the user's native
language is requested. */
#undef ENABLE_NLS
diff --git a/bfd/configure b/bfd/configure
index 6c2b24e..d1fe335 100755
--- a/bfd/configure
+++ b/bfd/configure
@@ -793,6 +793,7 @@ enable_targets
enable_64_bit_archive
with_mmap
enable_secureplt
+enable_separate_code
enable_leading_mingw64_underscores
with_separate_debug_dir
with_pkgversion
@@ -1446,6 +1447,7 @@ Optional Features:
--enable-targets alternative target configurations
--enable-64-bit-archive force 64-bit archives
--enable-secureplt Default to creating read-only plt entries
+ --enable-separate-code enable -z separate-code in ELF linker by default
--enable-leading-mingw64-underscores
Enable leading underscores on 64 bit mingw targets
--enable-werror treat compile warnings as errors
@@ -11428,7 +11430,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11431 "configure"
+#line 11433 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -11534,7 +11536,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11537 "configure"
+#line 11539 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -12171,6 +12173,33 @@ $as_echo "#define USE_SECUREPLT 1" >>confdefs.h
fi
+# Decide if -z separate-code should be enabled in ELF linker by default.
+ac_default_ld_z_separate_code=unset
+# Check whether --enable-separate-code was given.
+if test "${enable_separate_code+set}" = set; then :
+ enableval=$enable_separate_code; case "${enableval}" in
+ yes) ac_default_ld_z_separate_code=1 ;;
+ no) ac_default_ld_z_separate_code=0 ;;
+esac
+fi
+
+# Enable -z separate-code by default for Linux/x86.
+case "${target}" in
+i3-786-*-linux-* | x86_64-*-linux-*)
+ if test ${ac_default_ld_z_separate_code} = unset; then
+ ac_default_ld_z_separate_code=1
+ fi
+ ;;
+esac
+if test "${ac_default_ld_z_separate_code}" = unset; then
+ ac_default_ld_z_separate_code=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_LD_Z_SEPARATE_CODE $ac_default_ld_z_separate_code
+_ACEOF
+
+
# Check whether --enable-leading-mingw64-underscores was given.
if test "${enable_leading_mingw64_underscores+set}" = set; then :
enableval=$enable_leading_mingw64_underscores;
diff --git a/bfd/configure.ac b/bfd/configure.ac
index 2342f3f..20e2c02 100644
--- a/bfd/configure.ac
+++ b/bfd/configure.ac
@@ -97,6 +97,30 @@ if test $use_secureplt = true; then
[Define if we should default to creating read-only plt entries])
fi
+# Decide if -z separate-code should be enabled in ELF linker by default.
+ac_default_ld_z_separate_code=unset
+AC_ARG_ENABLE(separate-code,
+ AS_HELP_STRING([--enable-separate-code],
+ [enable -z separate-code in ELF linker by default]),
+[case "${enableval}" in
+ yes) ac_default_ld_z_separate_code=1 ;;
+ no) ac_default_ld_z_separate_code=0 ;;
+esac])
+# Enable -z separate-code by default for Linux/x86.
+case "${target}" in
+i[3-7]86-*-linux-* | x86_64-*-linux-*)
+ if test ${ac_default_ld_z_separate_code} = unset; then
+ ac_default_ld_z_separate_code=1
+ fi
+ ;;
+esac
+if test "${ac_default_ld_z_separate_code}" = unset; then
+ ac_default_ld_z_separate_code=0
+fi
+AC_DEFINE_UNQUOTED(DEFAULT_LD_Z_SEPARATE_CODE,
+ $ac_default_ld_z_separate_code,
+ [Define to 1 if you want to enable -z separate-code in ELF linker by default.])
+
AC_ARG_ENABLE(leading-mingw64-underscores,
AS_HELP_STRING([--enable-leading-mingw64-underscores],
[Enable leading underscores on 64 bit mingw targets]),
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 02a3d37..7016964 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -4942,7 +4942,11 @@ elf_x86_64_special_sections[]=
#define ELF_ARCH bfd_arch_i386
#define ELF_TARGET_ID X86_64_ELF_DATA
#define ELF_MACHINE_CODE EM_X86_64
-#define ELF_MAXPAGESIZE 0x200000
+#if DEFAULT_LD_Z_SEPARATE_CODE
+# define ELF_MAXPAGESIZE 0x1000
+#else
+# define ELF_MAXPAGESIZE 0x200000
+#endif
#define ELF_MINPAGESIZE 0x1000
#define ELF_COMMONPAGESIZE 0x1000
@@ -5335,7 +5339,11 @@ elf64_l1om_elf_object_p (bfd *abfd)
#undef ELF_MAXPAGESIZE
#undef ELF_MINPAGESIZE
#undef ELF_COMMONPAGESIZE
-#define ELF_MAXPAGESIZE 0x200000
+#if DEFAULT_LD_Z_SEPARATE_CODE
+# define ELF_MAXPAGESIZE 0x1000
+#else
+# define ELF_MAXPAGESIZE 0x200000
+#endif
#define ELF_MINPAGESIZE 0x1000
#define ELF_COMMONPAGESIZE 0x1000
#undef elf_backend_plt_alignment
diff --git a/ld/ChangeLog b/ld/ChangeLog
index d117b7e..07c86ef 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,15 @@
+2018-02-27 H.J. Lu <hongjiu.lu@intel.com>
+
+ * NEWS: Mention --enable-separate-code.
+ * configure.ac: Add --enable-separate-code.
+ (DEFAULT_LD_Z_SEPARATE_CODE): New AC_DEFINE_UNQUOTED.
+ * configure.tgt: Default ac_default_ld_z_separate_code to 1 for
+ Linux/x86 targets.
+ * config.in: Regenerated.
+ * configure: Likewise.
+ * emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
+ link_info.separate_code DEFAULT_LD_Z_SEPARATE_CODE.
+
2018-02-26 Alan Modra <amodra@gmail.com>
* emulparams/call_nop.sh, * emulparams/cet.sh,
diff --git a/ld/NEWS b/ld/NEWS
index eafcaf3..75f8100 100644
--- a/ld/NEWS
+++ b/ld/NEWS
@@ -1,5 +1,10 @@
-*- text -*-
+* Add a configure option --enable-separate-code to decide whether
+ -z separate-code should be enabled in ELF linker by default. Default
+ to yes for Linux/x86 targets. Note that -z separate-code can increase
+ disk and memory size.
+
Changes in 2.30:
* Add -z separate-code to generate separate code PT_LOAD segment.
diff --git a/ld/config.in b/ld/config.in
index a846743..b227a53 100644
--- a/ld/config.in
+++ b/ld/config.in
@@ -19,6 +19,10 @@
/* Define to 1 if you want to enable -z relro in ELF linker by default. */
#undef DEFAULT_LD_Z_RELRO
+/* Define to 1 if you want to enable -z separate-code in ELF linker by
+ default. */
+#undef DEFAULT_LD_Z_SEPARATE_CODE
+
/* Define to 1 if you want to set DT_RUNPATH instead of DT_RPATH by default.
*/
#undef DEFAULT_NEW_DTAGS
diff --git a/ld/configure b/ld/configure
index 17604bb..38f9739 100755
--- a/ld/configure
+++ b/ld/configure
@@ -790,6 +790,7 @@ enable_got
enable_compressed_debug_sections
enable_new_dtags
enable_relro
+enable_separate_code
enable_default_hash_style
enable_werror
enable_build_warnings
@@ -1451,6 +1452,7 @@ Optional Features:
compress debug sections by default]
--enable-new-dtags set DT_RUNPATH instead of DT_RPATH by default]
--enable-relro enable -z relro in ELF linker by default
+ --enable-separate-code enable -z separate-code in ELF linker by default
--enable-default-hash-style={sysv,gnu,both}
use this default hash style
--enable-werror treat compile warnings as errors
@@ -11725,7 +11727,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11728 "configure"
+#line 11730 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -11831,7 +11833,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11834 "configure"
+#line 11836 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -15567,6 +15569,17 @@ if test "${enable_relro+set}" = set; then :
esac
fi
+# Decide if -z separate-code should be enabled in ELF linker by default.
+ac_default_ld_z_separate_code=unset
+# Check whether --enable-separate-code was given.
+if test "${enable_separate_code+set}" = set; then :
+ enableval=$enable_separate_code; case "${enableval}" in
+ yes) ac_default_ld_z_separate_code=1 ;;
+ no) ac_default_ld_z_separate_code=0 ;;
+esac
+fi
+
+
# Decide which "--hash-style" to use by default
# Provide a configure time option to override our default.
# Check whether --enable-default-hash-style was given.
@@ -17258,6 +17271,15 @@ cat >>confdefs.h <<_ACEOF
_ACEOF
+if test "${ac_default_ld_z_separate_code}" = unset; then
+ ac_default_ld_z_separate_code=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define DEFAULT_LD_Z_SEPARATE_CODE $ac_default_ld_z_separate_code
+_ACEOF
+
+
cat >>confdefs.h <<_ACEOF
#define DEFAULT_EMIT_SYSV_HASH $ac_default_emit_sysv_hash
diff --git a/ld/configure.ac b/ld/configure.ac
index 6da8c8e..3552926 100644
--- a/ld/configure.ac
+++ b/ld/configure.ac
@@ -177,6 +177,16 @@ AC_ARG_ENABLE(relro,
no) ac_default_ld_z_relro=0 ;;
esac])dnl
+# Decide if -z separate-code should be enabled in ELF linker by default.
+ac_default_ld_z_separate_code=unset
+AC_ARG_ENABLE(separate-code,
+ AS_HELP_STRING([--enable-separate-code],
+ [enable -z separate-code in ELF linker by default]),
+[case "${enableval}" in
+ yes) ac_default_ld_z_separate_code=1 ;;
+ no) ac_default_ld_z_separate_code=0 ;;
+esac])
+
# Decide which "--hash-style" to use by default
# Provide a configure time option to override our default.
AC_ARG_ENABLE([default-hash-style],
@@ -434,6 +444,13 @@ AC_DEFINE_UNQUOTED(DEFAULT_LD_Z_RELRO,
$ac_default_ld_z_relro,
[Define to 1 if you want to enable -z relro in ELF linker by default.])
+if test "${ac_default_ld_z_separate_code}" = unset; then
+ ac_default_ld_z_separate_code=0
+fi
+AC_DEFINE_UNQUOTED(DEFAULT_LD_Z_SEPARATE_CODE,
+ $ac_default_ld_z_separate_code,
+ [Define to 1 if you want to enable -z separate-code in ELF linker by default.])
+
AC_DEFINE_UNQUOTED([DEFAULT_EMIT_SYSV_HASH],
[$ac_default_emit_sysv_hash],
[Define to 1 if you want to emit sysv hash in the ELF linker by default.])
diff --git a/ld/configure.tgt b/ld/configure.tgt
index 6183a85..7897448 100644
--- a/ld/configure.tgt
+++ b/ld/configure.tgt
@@ -968,3 +968,12 @@ frv-*-* | hppa*-*-* | ia64-*-* | mips*-*-*)
fi
;;
esac
+
+# Enable -z separate-code by default for Linux/x86.
+case "${target}" in
+i[3-7]86-*-linux-* | x86_64-*-linux-*)
+ if test ${ac_default_ld_z_separate_code} = unset; then
+ ac_default_ld_z_separate_code=1
+ fi
+ ;;
+esac
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index aae9d1f..9b8971e 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -106,6 +106,7 @@ gld${EMULATION_NAME}_before_parse (void)
`if test -n "$CALL_NOP_BYTE" ; then echo link_info.call_nop_byte = $CALL_NOP_BYTE; fi`;
link_info.check_relocs_after_open_input = TRUE;
link_info.relro = DEFAULT_LD_Z_RELRO;
+ link_info.separate_code = DEFAULT_LD_Z_SEPARATE_CODE;
}
EOF