commit 7b1f9406761331cf35fe521fbdb592beecf68a2c

Author: H.J. Lu <hjl.tools@gmail.com>

Date:   Fri Sep 28 13:31:19 2018 -0700

    i386: Use _dl_runtime_[resolve|profile]_shstk for SHSTK [BZ #23716]

    When elf_machine_runtime_setup is called to set up resolver, it should

    use _dl_runtime_resolve_shstk or _dl_runtime_profile_shstk if SHSTK is

    enabled by kernel.

    Tested on i686 with and without --enable-cet as well as on CET emulator

    with --enable-cet.

            [BZ #23716]

            * sysdeps/i386/dl-cet.c: Removed.

            * sysdeps/i386/dl-machine.h (_dl_runtime_resolve_shstk): New

            prototype.

            (_dl_runtime_profile_shstk): Likewise.

            (elf_machine_runtime_setup): Use _dl_runtime_profile_shstk or

            _dl_runtime_resolve_shstk if SHSTK is enabled by kernel.

    Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

diff --git a/sysdeps/i386/dl-cet.c b/sysdeps/i386/dl-cet.c

deleted file mode 100644

index 5d9a4e8d5179b572..0000000000000000

--- a/sysdeps/i386/dl-cet.c

+++ /dev/null

@@ -1,67 +0,0 @@

-/* Linux/i386 CET initializers function.

-   Copyright (C) 2018 Free Software Foundation, Inc.

-

-   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/>.  */

-

-

-#define LINKAGE static inline

-#define _dl_cet_check cet_check

-#include <sysdeps/x86/dl-cet.c>

-#undef _dl_cet_check

-

-#ifdef SHARED

-void

-_dl_cet_check (struct link_map *main_map, const char *program)

-{

-  cet_check (main_map, program);

-

-  if ((GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK))

-    {

-      /* Replace _dl_runtime_resolve and _dl_runtime_profile with

-         _dl_runtime_resolve_shstk and _dl_runtime_profile_shstk,

-	 respectively if SHSTK is enabled.  */

-      extern void _dl_runtime_resolve (Elf32_Word) attribute_hidden;

-      extern void _dl_runtime_resolve_shstk (Elf32_Word) attribute_hidden;

-      extern void _dl_runtime_profile (Elf32_Word) attribute_hidden;

-      extern void _dl_runtime_profile_shstk (Elf32_Word) attribute_hidden;

-      unsigned int i;

-      struct link_map *l;

-      Elf32_Addr *got;

-

-      if (main_map->l_info[DT_JMPREL])

-	{

-	  got = (Elf32_Addr *) D_PTR (main_map, l_info[DT_PLTGOT]);

-	  if (got[2] == (Elf32_Addr) &_dl_runtime_resolve)

-	    got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk;

-	  else if (got[2] == (Elf32_Addr) &_dl_runtime_profile)

-	    got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk;

-	}

-

-      i = main_map->l_searchlist.r_nlist;

-      while (i-- > 0)

-	{

-	  l = main_map->l_initfini[i];

-	  if (l->l_info[DT_JMPREL])

-	    {

-	      got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);

-	      if (got[2] == (Elf32_Addr) &_dl_runtime_resolve)

-		got[2] = (Elf32_Addr) &_dl_runtime_resolve_shstk;

-	      else if (got[2] == (Elf32_Addr) &_dl_runtime_profile)

-		got[2] = (Elf32_Addr) &_dl_runtime_profile_shstk;

-	    }

-	}

-    }

-}

-#endif

diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h

index 1afdcbd9ea2626e4..f6cfb90e21015250 100644

--- a/sysdeps/i386/dl-machine.h

+++ b/sysdeps/i386/dl-machine.h

@@ -67,6 +67,11 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)

   Elf32_Addr *got;

   extern void _dl_runtime_resolve (Elf32_Word) attribute_hidden;

   extern void _dl_runtime_profile (Elf32_Word) attribute_hidden;

+  extern void _dl_runtime_resolve_shstk (Elf32_Word) attribute_hidden;

+  extern void _dl_runtime_profile_shstk (Elf32_Word) attribute_hidden;

+  /* Check if SHSTK is enabled by kernel.  */

+  bool shstk_enabled

+    = (GL(dl_x86_feature_1)[0] & GNU_PROPERTY_X86_FEATURE_1_SHSTK) != 0;

   if (l->l_info[DT_JMPREL] && lazy)

     {

@@ -93,7 +98,9 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)

 	 end in this function.  */

       if (__glibc_unlikely (profile))

 	{

-	  got[2] = (Elf32_Addr) &_dl_runtime_profile;

+	  got[2] = (shstk_enabled

+		    ? (Elf32_Addr) &_dl_runtime_profile_shstk

+		    : (Elf32_Addr) &_dl_runtime_profile);

 	  if (GLRO(dl_profile) != NULL

 	      && _dl_name_match_p (GLRO(dl_profile), l))

@@ -104,7 +111,9 @@ elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)

       else

 	/* This function will get called to fix up the GOT entry indicated by

 	   the offset on the stack, and then jump to the resolved address.  */

-	got[2] = (Elf32_Addr) &_dl_runtime_resolve;

+	got[2] = (shstk_enabled

+		  ? (Elf32_Addr) &_dl_runtime_resolve_shstk

+		  : (Elf32_Addr) &_dl_runtime_resolve);

     }

   return lazy;