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[PATCH] fork in libpthread cannot use IFUNC resolver [BZ #19861]
- From: fweimer at redhat dot com (Florian Weimer)
- To: libc-alpha at sourceware dot org
- Date: Tue, 24 May 2016 11:10:19 +0200
- Subject: [PATCH] fork in libpthread cannot use IFUNC resolver [BZ #19861]
- Authentication-results: sourceware.org; auth=none
The __libc_fork symbol may not have been relocated when the
resolver runs. This commit only addresses the fork case,
the vfork case has to be a tail call, which is why the generic
code needs an IFUNC resolver there.
2016-05-24 Florian Weimer <fweimer@redhat.com>
[BZ #19861]
Do not use IFUNC resolver with potentially unrelcated symbol.
* nptl/pt-fork.c [HAVE_IFUNC]: Remove.
diff --git a/nptl/pt-fork.c b/nptl/pt-fork.c
index b65d6b4..9773dc4 100644
--- a/nptl/pt-fork.c
+++ b/nptl/pt-fork.c
@@ -25,48 +25,20 @@
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 __fork and fork symbols in
- libpthread.so; so we define them using IFUNC to redirect to the libc
- function. */
+ libpthread.so. */
#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
-# if HAVE_IFUNC
-
-static __typeof (fork) *
-__attribute__ ((used))
-fork_resolve (void)
-{
- return &__libc_fork;
-}
-
-# ifdef HAVE_ASM_SET_DIRECTIVE
-# define DEFINE_FORK(name) \
- asm (".set " #name ", fork_resolve\n" \
- ".globl " #name "\n" \
- ".type " #name ", %gnu_indirect_function");
-# else
-# define DEFINE_FORK(name) \
- asm (#name " = fork_resolve\n" \
- ".globl " #name "\n" \
- ".type " #name ", %gnu_indirect_function");
-# endif
-
-# else /* !HAVE_IFUNC */
-
static pid_t __attribute__ ((used))
fork_compat (void)
{
return __libc_fork ();
}
-# define DEFINE_FORK(name) strong_alias (fork_compat, name)
-
-# endif /* HAVE_IFUNC */
-
-DEFINE_FORK (fork_ifunc)
+strong_alias (fork_compat, fork_ifunc)
compat_symbol (libpthread, fork_ifunc, fork, GLIBC_2_0);
-DEFINE_FORK (__fork_ifunc)
+strong_alias (fork_compat, __fork_ifunc)
compat_symbol (libpthread, __fork_ifunc, __fork, GLIBC_2_0);
#endif