diff options
| author | H.J. Lu <hjl.tools@gmail.com> | 2016-05-24 08:44:10 -0700 |
|---|---|---|
| committer | H.J. Lu <hjl.tools@gmail.com> | 2016-05-24 08:44:23 -0700 |
| commit | 6901def689b5c77465d34f07822989ec67e80c1e (patch) | |
| tree | 2efde72294545c6b0129133d43d1f7335182fa61 | |
| parent | 4c011268960c6f24650672597deed756f21ad363 (diff) | |
Avoid an extra branch to PLT for -z now
When --enable-bind-now is used to configure glibc build, we can avoid
an extra branch to the PLT entry by using indirect branch via the GOT
slot instead, which is similar to the first instructuon in the PLT
entry. Changes in the shared library sizes in text sections:
Shared library Before (bytes) After (bytes)
libm.so 1060813 1060797
libmvec.so 160881 160805
libpthread.so 94992 94984
librt.so 25064 25048
* config.h.in (BIND_NOW): New.
* configure.ac (BIND_NOW): New. Defined for --enable-bind-now.
* configure: Regenerated.
* sysdeps/x86_64/sysdep.h (JUMPTARGET)[BIND_NOW]: Defined to
indirect branch via the GOT slot.
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | config.h.in | 3 | ||||
| -rwxr-xr-x | configure | 4 | ||||
| -rw-r--r-- | configure.ac | 3 | ||||
| -rw-r--r-- | sysdeps/x86_64/sysdep.h | 8 |
5 files changed, 24 insertions, 2 deletions
@@ -1,3 +1,11 @@ +2016-05-24 H.J. Lu <hongjiu.lu@intel.com> + + * config.h.in (BIND_NOW): New. + * configure.ac (BIND_NOW): New. Defined for --enable-bind-now. + * configure: Regenerated. + * sysdeps/x86_64/sysdep.h (JUMPTARGET)[BIND_NOW]: Defined to + indirect branch via the GOT slot. + 2016-05-24 Stefan Liebler <stli@linux.vnet.ibm.com> [BZ #19765] diff --git a/config.h.in b/config.h.in index 0147ba3c34..2c902b0214 100644 --- a/config.h.in +++ b/config.h.in @@ -87,6 +87,9 @@ include/libc-symbols.h that avoid PLT slots in the shared objects. */ #undef NO_HIDDEN +/* Define this to disable lazy relocations in DSOs. */ +#undef BIND_NOW + /* AArch64 big endian ABI */ #undef HAVE_AARCH64_BE @@ -3416,6 +3416,10 @@ else fi +if test "x$bindnow" = xyes; then + $as_echo "#define BIND_NOW 1" >>confdefs.h + +fi # Check whether --enable-static-nss was given. if test "${enable_static_nss+set}" = set; then : diff --git a/configure.ac b/configure.ac index 3c766b7409..123f0d26ee 100644 --- a/configure.ac +++ b/configure.ac @@ -231,6 +231,9 @@ AC_ARG_ENABLE([bind-now], [bindnow=$enableval], [bindnow=no]) AC_SUBST(bindnow) +if test "x$bindnow" = xyes; then + AC_DEFINE(BIND_NOW) +fi dnl On some platforms we cannot use dynamic loading. We must provide dnl static NSS modules. diff --git a/sysdeps/x86_64/sysdep.h b/sysdeps/x86_64/sysdep.h index fbe3560588..75ac747be8 100644 --- a/sysdeps/x86_64/sysdep.h +++ b/sysdeps/x86_64/sysdep.h @@ -90,9 +90,13 @@ lose: \ #undef JUMPTARGET #ifdef PIC -#define JUMPTARGET(name) name##@PLT +# ifdef BIND_NOW +# define JUMPTARGET(name) *name##@GOTPCREL(%rip) +# else +# define JUMPTARGET(name) name##@PLT +# endif #else -#define JUMPTARGET(name) name +# define JUMPTARGET(name) name #endif /* Local label name for asm code. */ |