Index: glibc-2.17-c758a686/elf/rtld.c

===================================================================

--- glibc-2.17-c758a686.orig/elf/rtld.c

+++ glibc-2.17-c758a686/elf/rtld.c

@@ -2478,6 +2478,11 @@ process_envvars (enum mode *modep)

   GLRO(dl_profile_output)

     = &"/var/tmp\0/var/profile"[INTUSE(__libc_enable_secure) ? 9 : 0];

+  /* RHEL 7 specific change:

+     Without the tunables farmework we simulate tunables only for

+     use with enabling transactional memory.  */

+  _dl_process_tunable_env_entries ();

+

   while ((envline = _dl_next_ld_env_entry (&runp)) != NULL)

     {

       size_t len = 0;

Index: glibc-2.17-c758a686/nptl/sysdeps/unix/sysv/linux/x86/elision-conf.c

===================================================================

--- glibc-2.17-c758a686.orig/nptl/sysdeps/unix/sysv/linux/x86/elision-conf.c

+++ glibc-2.17-c758a686/nptl/sysdeps/unix/sysv/linux/x86/elision-conf.c

@@ -68,8 +68,18 @@ elision_init (int argc __attribute__ ((u

 {

   int elision_available = HAS_CPU_FEATURE (RTM);

 #ifdef ENABLE_LOCK_ELISION

-  __pthread_force_elision = __libc_enable_secure ? 0 : elision_available;

-  __rwlock_rtm_enabled = __libc_enable_secure ? 0 : elision_available;

+  if (!__libc_enable_secure && elision_available)

+    {

+      /* RHEL 7 specific change: Check if elision is enabled for the

+	 process.  */

+      __pthread_force_elision = GLRO(dl_elision_enabled);

+      __rwlock_rtm_enabled = GLRO(dl_elision_enabled);

+    }

+  else

+    {

+      __pthread_force_elision = 0;

+      __rwlock_rtm_enabled = 0;

+    }

 #endif

 }

Index: glibc-2.17-c758a686/sysdeps/generic/ldsodefs.h

===================================================================

--- glibc-2.17-c758a686.orig/sysdeps/generic/ldsodefs.h

+++ glibc-2.17-c758a686/sysdeps/generic/ldsodefs.h

@@ -557,6 +557,9 @@ struct rtld_global_ro

      platforms.  */

   EXTERN uint64_t _dl_hwcap2;

+  /* RHEL 7 specific change: Is elision enabled for this process?  */

+  EXTERN bool _dl_elision_enabled;

+

 #ifdef SHARED

   /* We add a function table to _rtld_global which is then used to

      call the function instead of going through the PLT.  The result

@@ -893,6 +896,10 @@ extern void _dl_show_auxv (void) interna

    other.  */

 extern char *_dl_next_ld_env_entry (char ***position) internal_function;

+/* RHEL 7 specific change:

+   Manually process RHEL 7-specific tunable entries.  */

+extern void _dl_process_tunable_env_entries (void) internal_function;

+

 /* Return an array with the names of the important hardware capabilities.  */

 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,

 							size_t paltform_len,

Index: glibc-2.17-c758a686/elf/dl-support.c

===================================================================

--- glibc-2.17-c758a686.orig/elf/dl-support.c

+++ glibc-2.17-c758a686/elf/dl-support.c

@@ -123,6 +123,10 @@ size_t _dl_phnum;

 uint64_t _dl_hwcap __attribute__ ((nocommon));

 uint64_t _dl_hwcap2 __attribute__ ((nocommon));

+/* RHEL 7-specific change: Is elision enabled for the process?

+   Static library definition.  */

+bool _dl_elision_enabled;

+

 /* This is not initialized to HWCAP_IMPORTANT, matching the definition

    of _dl_important_hwcaps, below, where no hwcap strings are ever

    used.  This mask is still used to mediate the lookups in the cache

@@ -289,6 +293,9 @@ _dl_non_dynamic_init (void)

     _dl_profile_output

       = &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];

+  /* RHEL 7 specific change: Process tunables at startup.  */

+  _dl_process_tunable_env_entries ();

+

   if (__libc_enable_secure)

     {

       static const char unsecure_envvars[] =

Index: glibc-2.17-c758a686/sysdeps/x86_64/multiarch/strstr-c.c

===================================================================

--- glibc-2.17-c758a686.orig/sysdeps/x86_64/multiarch/strstr-c.c

+++ glibc-2.17-c758a686/sysdeps/x86_64/multiarch/strstr-c.c

@@ -17,6 +17,10 @@

    License along with the GNU C Library; if not, see

    <http://www.gnu.org/licenses/>.  */

+/* RHEL 7-specific: Define multiple versions only for the definition in

+   libc.  Don't define multiple versions for strstr in static library

+   since we need strstr before initialization has happened.  */

+#if defined SHARED && IS_IN (libc)

 /* Redefine strstr so that the compiler won't complain about the type

    mismatch with the IFUNC selector in strong_alias, below.  */

 #undef  strstr

@@ -30,9 +34,11 @@

 # define libc_hidden_builtin_def(name) \

   __hidden_ver1 (__strstr_sse2, __GI_strstr, __strstr_sse2);

 #endif

+#endif

 #include "string/strstr.c"

+#if defined SHARED && IS_IN (libc)

 extern __typeof (__redirect_strstr) __strstr_sse42 attribute_hidden;

 extern __typeof (__redirect_strstr) __strstr_sse2_unaligned attribute_hidden;

 extern __typeof (__redirect_strstr) __strstr_sse2 attribute_hidden;

@@ -48,3 +54,5 @@ libc_ifunc (__libc_strstr, HAS_CPU_FEATU

 #undef strstr

 strong_alias (__libc_strstr, strstr)

+#endif

+

Index: glibc-2.17-c758a686/elf/Makefile

===================================================================

--- glibc-2.17-c758a686.orig/elf/Makefile

+++ glibc-2.17-c758a686/elf/Makefile

@@ -35,6 +35,10 @@ dl-routines	= $(addprefix dl-,load looku

 ifeq (yes,$(use-ldconfig))

 dl-routines += dl-cache

 endif

+

+# RHEL 7-specific change: Add rudimentary tunables support.

+dl-routines += dl-tunables

+

 all-dl-routines = $(dl-routines) $(sysdep-dl-routines)

 # But they are absent from the shared libc, because that code is in ld.so.

 elide-routines.os = $(all-dl-routines) dl-support enbl-secure dl-origin \

Index: glibc-2.17-c758a686/elf/dl-tunables.c

===================================================================

--- /dev/null

+++ glibc-2.17-c758a686/elf/dl-tunables.c

@@ -0,0 +1,60 @@

+/* RHEL 7-specific rudimentary tunables handling.

+   Copyright (C) 2017 Free Software Foundation, Inc.

+   This file is part of the GNU C Library.

+

+   The GNU C Library is free software; you can redistribute it and/or

+   modify it under the terms of the GNU Lesser General Public

+   License as published by the Free Software Foundation; either

+   version 2.1 of the License, or (at your option) any later version.

+

+   The GNU C Library is distributed in the hope that it will be useful,

+   but WITHOUT ANY WARRANTY; without even the implied warranty of

+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+   Lesser General Public License for more details.

+

+   You should have received a copy of the GNU Lesser General Public

+   License along with the GNU C Library; if not, see

+   <http://www.gnu.org/licenses/>.  */

+

+#include <string.h>

+#include <unistd.h>

+#include <ldsodefs.h>

+#include <elision-conf.h>

+

+/* RHEL 7 specific change:

+   Manually process RHEL 7-specific tunable entries.  */

+void

+internal_function

+_dl_process_tunable_env_entries (void)

+{

+#if HAVE_ELISION

+  char **ep;

+  const char *envname = { "RHEL_GLIBC_TUNABLES" };

+# define TUNABLE_ELISION 0

+# define TUNABLE_MAX 1

+  const char *tunables[TUNABLE_MAX] = { "glibc.elision.enable=1" };

+

+  ep = __environ;

+  while (*ep != NULL)

+    {

+      size_t cnt = 0;

+

+      while ((*ep)[cnt] == envname[cnt] && envname[cnt] != '\0')

+        ++cnt;

+

+      if (envname[cnt] == '\0' && (*ep)[cnt] == '=')

+        {

+          /* Found it.  */

+          char *found;

+          found = strstr (*ep, tunables[TUNABLE_ELISION]);

+          /* Process TUNABLE_ELISION:

+             Note: elision-conf.c applies security checks.  */

+          if (found != NULL)

+	    GLRO(dl_elision_enabled) = true;

+          /* Continue the loop in case NAME appears again.  */

+        }

+

+      ++ep;

+    }

+#endif

+}