RFC: x86: Enable -z separate-code by default

H.J. Lu hjl.tools@gmail.com
Mon Feb 19 13:16:00 GMT 2018


This patch enables -z separate-code by default for x86.  To reduce
x86-64 binary size, set ELF_MAXPAGESIZE to 4KB.

Should I add an ld configure option, --enable-separate-code, instead?


H.J.
---
bfd/
	* elf64-x86-64.c (ELF_MAXPAGESIZE): Set to 0x1000.

ld/

	* emulparams/elf32_x86_64.sh (DEFAULT_SEPARATE_CODE): New.
	* emulparams/elf_i386.sh (DEFAULT_SEPARATE_CODE): Likewise.
	* emulparams/elf_x86_64.sh (DEFAULT_SEPARATE_CODE): Likewise.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
	link_info.separate_code to TRUE if ${DEFAULT_SEPARATE_CODE} is
	yes.
---
 bfd/elf64-x86-64.c            | 4 ++--
 ld/emulparams/elf32_x86_64.sh | 1 +
 ld/emulparams/elf_i386.sh     | 1 +
 ld/emulparams/elf_x86_64.sh   | 1 +
 ld/emultempl/elf32.em         | 1 +
 5 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 00ed5d17a5..51c301bae6 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -4934,7 +4934,7 @@ 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
+#define ELF_MAXPAGESIZE			    0x1000
 #define ELF_MINPAGESIZE			    0x1000
 #define ELF_COMMONPAGESIZE		    0x1000
 
@@ -5327,7 +5327,7 @@ elf64_l1om_elf_object_p (bfd *abfd)
 #undef	ELF_MAXPAGESIZE
 #undef	ELF_MINPAGESIZE
 #undef	ELF_COMMONPAGESIZE
-#define ELF_MAXPAGESIZE			0x200000
+#define ELF_MAXPAGESIZE			0x1000
 #define ELF_MINPAGESIZE			0x1000
 #define ELF_COMMONPAGESIZE		0x1000
 #undef	elf_backend_plt_alignment
diff --git a/ld/emulparams/elf32_x86_64.sh b/ld/emulparams/elf32_x86_64.sh
index 9ce6533bd9..f8e004829d 100644
--- a/ld/emulparams/elf32_x86_64.sh
+++ b/ld/emulparams/elf32_x86_64.sh
@@ -14,6 +14,7 @@ COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)"
 ARCH="i386:x64-32"
 MACHINE=
 TEMPLATE_NAME=elf32
+DEFAULT_SEPARATE_CODE=yes
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
 NO_SMALL_DATA=yes
diff --git a/ld/emulparams/elf_i386.sh b/ld/emulparams/elf_i386.sh
index 2cef106e3d..6c451aac8a 100644
--- a/ld/emulparams/elf_i386.sh
+++ b/ld/emulparams/elf_i386.sh
@@ -12,6 +12,7 @@ COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)"
 ARCH=i386
 MACHINE=
 TEMPLATE_NAME=elf32
+DEFAULT_SEPARATE_CODE=yes
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
 NO_SMALL_DATA=yes
diff --git a/ld/emulparams/elf_x86_64.sh b/ld/emulparams/elf_x86_64.sh
index d8c6e54894..8e18d81bdf 100644
--- a/ld/emulparams/elf_x86_64.sh
+++ b/ld/emulparams/elf_x86_64.sh
@@ -14,6 +14,7 @@ COMMONPAGESIZE="CONSTANT (COMMONPAGESIZE)"
 ARCH="i386:x86-64"
 MACHINE=
 TEMPLATE_NAME=elf32
+DEFAULT_SEPARATE_CODE=yes
 GENERATE_SHLIB_SCRIPT=yes
 GENERATE_PIE_SCRIPT=yes
 NO_SMALL_DATA=yes
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index c0925fc9b9..1325b4742f 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -104,6 +104,7 @@ gld${EMULATION_NAME}_before_parse (void)
   config.has_shared = `if test -n "$GENERATE_SHLIB_SCRIPT" ; then echo TRUE ; else echo FALSE ; fi`;
   config.separate_code = `if test "x${SEPARATE_CODE}" = xyes ; then echo TRUE ; else echo FALSE ; fi`;
   `if test -n "$CALL_NOP_BYTE" ; then echo link_info.call_nop_byte = $CALL_NOP_BYTE; fi`;
+  link_info.separate_code = `if test "x${DEFAULT_SEPARATE_CODE}" = xyes ; then echo TRUE ; else echo FALSE ; fi`;
   link_info.check_relocs_after_open_input = TRUE;
   link_info.relro = DEFAULT_LD_Z_RELRO;
 }
-- 
2.14.3



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