[PATCH] Do not use IFUNC resolver with potentially unrelocated symbol.

[Yunlian Jiang <yunlian at chromium dot org>]

We got some error when upgrading glibc.
https://bugs.chromium.org/p/chromium/issues/detail?id=676693

With the patch below, it fixes the problem.

This does the similar fix from
commit f06f3f05b48c72e2c9b0fa78671f94fd22d67da8
to fix the issue for longjmp.
---
 nptl/pt-longjmp.c | 31 ++++++++++---------------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/nptl/pt-longjmp.c b/nptl/pt-longjmp.c
index a19cd59..51584a7 100644
--- a/nptl/pt-longjmp.c
+++ b/nptl/pt-longjmp.c
@@ -25,21 +25,14 @@
    symbol in libpthread, but the historical ABI requires it.  For static
    linking, there is no need to provide anything here--the libc version
    will be linked in.  For shared library ABI compatibility, there must be
-   longjmp and siglongjmp symbols in libpthread.so; so we define them using
-   IFUNC to redirect to the libc function.  */
+   longjmp and siglongjmp symbols in libpthread.so.

-#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
-
-# if HAVE_IFUNC
-
-#  undef INIT_ARCH
-#  define INIT_ARCH()
-#  define DEFINE_LONGJMP(name) libc_ifunc (name, &__libc_longjmp)
-
-extern __typeof(longjmp) longjmp_ifunc;
-extern __typeof(siglongjmp) siglongjmp_ifunc;
+   With an IFUNC resolver, it would be possible to avoid the
+   indirection, but the IFUNC resolver might run before the
+    __libc_longjmp symbol has been relocated, in which case the IFUNC
+   resolver would not be able to provide the correct address.  */

-# else  /* !HAVE_IFUNC */
+#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)

 static void __attribute__ ((noreturn, used))
 longjmp_compat (jmp_buf env, int val)
@@ -47,14 +40,10 @@ longjmp_compat (jmp_buf env, int val)
   __libc_longjmp (env, val);
 }

-# define DEFINE_LONGJMP(name) strong_alias (longjmp_compat, name)
-
-# endif  /* HAVE_IFUNC */
-
-DEFINE_LONGJMP (longjmp_ifunc)
-compat_symbol (libpthread, longjmp_ifunc, longjmp, GLIBC_2_0);
+strong_alias (longjmp_compat, longjmp_alias)
+compat_symbol (libpthread, longjmp_alias, longjmp, GLIBC_2_0);

-strong_alias (longjmp_ifunc, siglongjmp_ifunc)
-compat_symbol (libpthread, siglongjmp_ifunc, siglongjmp, GLIBC_2_0);
+strong_alias (longjmp_compat, siglongjmp_alias)
+compat_symbol (libpthread, siglongjmp_alias, siglongjmp, GLIBC_2_0);

 #endif
--
2.8.0.rc3.226.g39d4020