6 files changed, 165 insertions, 1 deletions
diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile
index e8babc9a4e..90f4ecfd26 100644
--- a/sysdeps/x86_64/Makefile
+++ b/sysdeps/x86_64/Makefile
@@ -10,7 +10,7 @@ LDFLAGS-rtld += -Wl,-z,nomark-plt
 endif
 
 ifeq ($(subdir),csu)
-gen-as-const-headers += link-defines.sym
+gen-as-const-headers += features-offsets.sym link-defines.sym
 endif
 
 ifeq ($(subdir),gmon)
diff --git a/sysdeps/x86_64/dl-procruntime.c b/sysdeps/x86_64/dl-procruntime.c
new file mode 100644
index 0000000000..7078581778
--- /dev/null
+++ b/sysdeps/x86_64/dl-procruntime.c
@@ -0,0 +1,78 @@
+/* Data for processor runtime information.  x86-64 version.
+   Copyright (C) 2018-2024 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
+   <https://www.gnu.org/licenses/>.  */
+
+/* This information must be kept in sync with the _DL_HWCAP_COUNT,
+   HWCAP_PLATFORMS_START and HWCAP_PLATFORMS_COUNT definitions in
+   dl-hwcap.h.
+
+   If anything should be added here check whether the size of each string
+   is still ok with the given array size.
+
+   All the #ifdefs in the definitions are quite irritating but
+   necessary if we want to avoid duplicating the information.  There
+   are three different modes:
+
+   - PROCINFO_DECL is defined.  This means we are only interested in
+     declarations.
+
+   - PROCINFO_DECL is not defined:
+
+     + if SHARED is defined the file is included in an array
+       initializer.  The .element = { ... } syntax is needed.
+
+     + if SHARED is not defined a normal array initialization is
+       needed.
+  */
+
+#ifndef PROCINFO_CLASS
+# define PROCINFO_CLASS
+#endif
+
+#if !IS_IN (ldconfig)
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_x86_feature_1
+# else
+PROCINFO_CLASS unsigned int _dl_x86_feature_1
+# endif
+# ifndef PROCINFO_DECL
+= 0
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+
+# if !defined PROCINFO_DECL && defined SHARED
+  ._dl_x86_feature_control
+# else
+PROCINFO_CLASS struct dl_x86_feature_control _dl_x86_feature_control
+# endif
+# ifndef PROCINFO_DECL
+= {
+    .ibt = DEFAULT_DL_X86_CET_CONTROL,
+    .shstk = DEFAULT_DL_X86_CET_CONTROL,
+    .plt_rewrite = plt_rewrite_none,
+  }
+# endif
+# if !defined SHARED || defined PROCINFO_DECL
+;
+# else
+,
+# endif
+#endif
diff --git a/sysdeps/x86_64/dl-trampoline.S b/sysdeps/x86_64/dl-trampoline.S
index 4c1ba5c9af..b2e7e0f69b 100644
--- a/sysdeps/x86_64/dl-trampoline.S
+++ b/sysdeps/x86_64/dl-trampoline.S
@@ -19,6 +19,7 @@
 #include <config.h>
 #include <sysdep.h>
 #include <cpu-features-offsets.h>
+#include <features-offsets.h>
 #include <link-defines.h>
 #include <isa-level.h>
 
diff --git a/sysdeps/x86_64/feature-control.h b/sysdeps/x86_64/feature-control.h
new file mode 100644
index 0000000000..4c8727e844
--- /dev/null
+++ b/sysdeps/x86_64/feature-control.h
@@ -0,0 +1,53 @@
+/* x86-64 feature tuning.
+   This file is part of the GNU C Library.
+   Copyright (C) 2018-2024 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _X86_64_FEATURE_CONTROL_H
+#define _X86_64_FEATURE_CONTROL_H
+
+/* For each CET feature, IBT and SHSTK, valid control values.  */
+enum dl_x86_cet_control
+{
+  /* Enable CET features based on ELF property note.  */
+  cet_elf_property = 0,
+  /* Always enable CET features.  */
+  cet_always_on,
+  /* Always disable CET features.  */
+  cet_always_off,
+  /* Enable CET features permissively.  */
+  cet_permissive
+};
+
+/* PLT rewrite control.  */
+enum dl_plt_rewrite_control
+{
+  /* No PLT rewrite.  */
+  plt_rewrite_none,
+  /* Rewrite PLT with JMP at run-time.  */
+  plt_rewrite_jmp,
+  /* Rewrite PLT with JMP and JMPABS at run-time.  */
+  plt_rewrite_jmpabs
+};
+
+struct dl_x86_feature_control
+{
+  enum dl_x86_cet_control ibt : 2;
+  enum dl_x86_cet_control shstk : 2;
+  enum dl_plt_rewrite_control plt_rewrite : 2;
+};
+
+#endif /* feature-control.h */
diff --git a/sysdeps/x86_64/features-offsets.sym b/sysdeps/x86_64/features-offsets.sym
new file mode 100644
index 0000000000..9e4be3393a
--- /dev/null
+++ b/sysdeps/x86_64/features-offsets.sym
@@ -0,0 +1,6 @@
+#define SHARED 1
+
+#include <ldsodefs.h>
+
+RTLD_GLOBAL_RO_DL_X86_CPU_FEATURES_OFFSET offsetof (struct rtld_global_ro, _dl_x86_cpu_features)
+RTLD_GLOBAL_DL_X86_FEATURE_1_OFFSET offsetof (struct rtld_global, _dl_x86_feature_1)
diff --git a/sysdeps/x86_64/ldsodefs.h b/sysdeps/x86_64/ldsodefs.h
new file mode 100644
index 0000000000..0f468ddf5b
--- /dev/null
+++ b/sysdeps/x86_64/ldsodefs.h
@@ -0,0 +1,26 @@
+/* Run-time dynamic linker data structures for loaded ELF shared objects.
+   x86-64 version.
+   Copyright (C) 2024 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef	_X86_64_LDSODEFS_H
+#define	_X86_64_LDSODEFS_H	1
+
+#include <feature-control.h>
+#include_next <ldsodefs.h>
+
+#endif