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[v3,9/9] Use libc_ifunc macro for siglongjmp, longjmp in libpthread.

Message ID 1472047472-30307-9-git-send-email-stli@linux.vnet.ibm.com
State New
Headers show

Commit Message

Stefan Liebler Aug. 24, 2016, 2:04 p.m. UTC 
This patch uses the libc_ifunc macro to create already existing ifunc functions
longjmp_ifunc, siglongjmp_ifunc if HAVE_IFUNC is defined.
The s390 pt-longjmp.c includes the common pt-longjmp.c and uses strong_alias
to create the longjmp, siglongjmp symbols for glibc version 2.19.

ChangeLog:

	* nptl/pt-longjmp.c (DEFINE_LONGJMP): Use libc_ifunc macro.
	* sysdeps/unix/sysv/linux/s390/pt-longjmp.c (longjmp, siglongjmp):
	Use strong_alias to create symbols for glibc verison 2.19.
---
 nptl/pt-longjmp.c                         | 24 ++++++------------------
 sysdeps/unix/sysv/linux/s390/pt-longjmp.c |  4 ++--
 2 files changed, 8 insertions(+), 20 deletions(-)

Comments

Florian Weimer Oct. 6, 2016, 11:59 a.m. UTC | #1 
On 08/24/2016 04:04 PM, Stefan Liebler wrote:
> This patch uses the libc_ifunc macro to create already existing ifunc functions
> longjmp_ifunc, siglongjmp_ifunc if HAVE_IFUNC is defined.
> The s390 pt-longjmp.c includes the common pt-longjmp.c and uses strong_alias
> to create the longjmp, siglongjmp symbols for glibc version 2.19.
>
> ChangeLog:
>
> 	* nptl/pt-longjmp.c (DEFINE_LONGJMP): Use libc_ifunc macro.
> 	* sysdeps/unix/sysv/linux/s390/pt-longjmp.c (longjmp, siglongjmp):
> 	Use strong_alias to create symbols for glibc verison 2.19.

This is okay for now.

Once this is in, I'm going to submit a patch which replaces the IFUNC 
resolver with a direct call (similar to what we did for fork) because of 
the relocation ordering issue that can cause those IFUNC resolvers to go 
wrong.

Thanks,
Florian
diff mbox

Patch

diff --git a/nptl/pt-longjmp.c b/nptl/pt-longjmp.c
index a1cc286..a19cd59 100644
--- a/nptl/pt-longjmp.c
+++ b/nptl/pt-longjmp.c
@@ -32,24 +32,12 @@ 
 
 # if HAVE_IFUNC
 
-static __typeof (longjmp) *
-__attribute__ ((used))
-longjmp_resolve (void)
-{
-  return &__libc_longjmp;
-}
+#  undef INIT_ARCH
+#  define INIT_ARCH()
+#  define DEFINE_LONGJMP(name) libc_ifunc (name, &__libc_longjmp)
 
-#  ifdef HAVE_ASM_SET_DIRECTIVE
-#   define DEFINE_LONGJMP(name) \
-  asm (".set " #name ", longjmp_resolve\n" \
-       ".globl " #name "\n" \
-       ".type " #name ", %gnu_indirect_function");
-#  else
-#   define DEFINE_LONGJMP(name) \
-  asm (#name " = longjmp_resolve\n" \
-       ".globl " #name "\n" \
-       ".type " #name ", %gnu_indirect_function");
-#  endif
+extern __typeof(longjmp) longjmp_ifunc;
+extern __typeof(siglongjmp) siglongjmp_ifunc;
 
 # else  /* !HAVE_IFUNC */
 
@@ -66,7 +54,7 @@  longjmp_compat (jmp_buf env, int val)
 DEFINE_LONGJMP (longjmp_ifunc)
 compat_symbol (libpthread, longjmp_ifunc, longjmp, GLIBC_2_0);
 
-DEFINE_LONGJMP (siglongjmp_ifunc)
+strong_alias (longjmp_ifunc, siglongjmp_ifunc)
 compat_symbol (libpthread, siglongjmp_ifunc, siglongjmp, GLIBC_2_0);
 
 #endif
diff --git a/sysdeps/unix/sysv/linux/s390/pt-longjmp.c b/sysdeps/unix/sysv/linux/s390/pt-longjmp.c
index 10e825c..2abf112 100644
--- a/sysdeps/unix/sysv/linux/s390/pt-longjmp.c
+++ b/sysdeps/unix/sysv/linux/s390/pt-longjmp.c
@@ -26,8 +26,8 @@ 
 /* In glibc release 2.19 new versions of longjmp-functions were introduced,
    but were reverted before 2.20. Thus both versions are the same function.  */
 
-DEFINE_LONGJMP (__v2longjmp)
+strong_alias (longjmp_ifunc, __v2longjmp)
 compat_symbol (libpthread, __v2longjmp, longjmp, GLIBC_2_19);
-DEFINE_LONGJMP (__v2siglongjmp)
+strong_alias (siglongjmp_ifunc, __v2siglongjmp)
 compat_symbol (libpthread, __v2siglongjmp, siglongjmp, GLIBC_2_19);
 #endif /* SHLIB_COMPAT (libpthread, GLIBC_2_19, GLIBC_2_20))  */