GNU C Library master sources branch master updated. glibc-2.26-46-gfc5ad70

[schwab at sourceware dot org]

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- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=fc5ad7024c620cdfe9b76e94638aac83b99c5bf8

commit fc5ad7024c620cdfe9b76e94638aac83b99c5bf8
Author: Andreas Schwab <schwab@suse.de>
Date:   Tue Aug 8 16:21:58 2017 +0200

    Don't use IFUNC resolver for longjmp or system in libpthread (bug 21041)
    
    Unlike the vfork forwarder and like the fork forwarder as in bug 19861,
    there won't be a problem when the compiler does not turn this into a tail
    call.

diff --git a/ChangeLog b/ChangeLog
index 28051e0..5b30f0c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-08-08  Andreas Schwab  <schwab@suse.de>
+
+	[BZ #21041]
+	* nptl/pt-longjmp.c (longjmp, siglongjmp): Don't use IFUNC resolver.
+	* nptl/pt-system.c (system): Likewise.
+
 2017-08-07  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
 
 	[BZ #21780]
diff --git a/nptl/pt-longjmp.c b/nptl/pt-longjmp.c
index 2ef757e..8f3c6b3 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_alias, siglongjmp_alias)
+compat_symbol (libpthread, siglongjmp_alias, siglongjmp, GLIBC_2_0);
 
 #endif
diff --git a/nptl/pt-system.c b/nptl/pt-system.c
index f8ca6ba..b30ddf2 100644
--- a/nptl/pt-system.c
+++ b/nptl/pt-system.c
@@ -25,29 +25,21 @@
    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 a
-   'system' symbol in libpthread.so; so we define it using IFUNC to
-   redirect to the libc function.  */
+   'system' symbol in libpthread.so.
 
-#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_22)
-
-# if HAVE_IFUNC
-
-extern __typeof(system) system_ifunc;
-#  undef INIT_ARCH
-#  define INIT_ARCH()
-libc_ifunc (system_ifunc, &__libc_system)
+   With an IFUNC resolver, it would be possible to avoid the indirection,
+   but the IFUNC resolver might run before the __libc_system 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 int __attribute__ ((used))
 system_compat (const char *line)
 {
   return __libc_system (line);
 }
-strong_alias (system_compat, system_ifunc)
-
-# endif  /* HAVE_IFUNC */
-
-compat_symbol (libpthread, system_ifunc, system, GLIBC_2_0);
+strong_alias (system_compat, system_alias)
+compat_symbol (libpthread, system_alias, system, GLIBC_2_0);
 
 #endif

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog         |    6 ++++++
 nptl/pt-longjmp.c |   31 ++++++++++---------------------
 nptl/pt-system.c  |   24 ++++++++----------------
 3 files changed, 24 insertions(+), 37 deletions(-)


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