x86: Rename __glibc_reserved1 to feature_1 in tcbhead_t [BZ #22563]

feature_1 has X86_FEATURE_1_IBT and X86_FEATURE_1_SHSTK bits for CET
run-time control.

CET_ENABLED, IBT_ENABLED and SHSTK_ENABLED are defined to 1 or 0 to
indicate that if CET, IBT and SHSTK are enabled.

<tls-setup.h> is added to set up thread-local data.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	[BZ #22563]
	* nptl/pthread_create.c: Include <tls-setup.h>.
	(__pthread_create_2_1): Call tls_setup_tcbhead.
	* sysdeps/generic/tls-setup.h: New file.
	* sysdeps/x86/nptl/tls-setup.h: Likewise.
	* sysdeps/i386/nptl/tcb-offsets.sym (FEATURE_1_OFFSET): New.
	* sysdeps/x86_64/nptl/tcb-offsets.sym (FEATURE_1_OFFSET):
	Likewise.
	* sysdeps/i386/nptl/tls.h (tcbhead_t): Rename __glibc_reserved1
	to feature_1.
	* sysdeps/x86_64/nptl/tls.h (tcbhead_t): Likewise.
	* sysdeps/x86/sysdep.h (X86_FEATURE_1_IBT): New.
	(X86_FEATURE_1_SHSTK): Likewise.
	(CET_ENABLED): Likewise.
	(IBT_ENABLED): Likewise.
	(SHSTK_ENABLED): Likewise.

7 files changed, 82 insertions, 2 deletions

diff --git a/sysdeps/generic/tls-setup.h b/sysdeps/generic/tls-setup.h
new file mode 100644
index 0000000000..8d0c36d2b8
--- /dev/null
+++ b/sysdeps/generic/tls-setup.h
@@ -0,0 +1,22 @@
+/* Definitions to set up thread-local data.  Generic version.
+   Copyright (C) 2018 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/>.  */
+
+static inline void __attribute__ ((always_inline))
+tls_setup_tcbhead (struct pthread *pd)
+{
+}
diff --git a/sysdeps/i386/nptl/tcb-offsets.sym b/sysdeps/i386/nptl/tcb-offsets.sym
index 7d7fe5e71c..fbac241c45 100644
--- a/sysdeps/i386/nptl/tcb-offsets.sym
+++ b/sysdeps/i386/nptl/tcb-offsets.sym
@@ -12,3 +12,4 @@ CLEANUP			offsetof (struct pthread, cleanup)
 CLEANUP_PREV		offsetof (struct _pthread_cleanup_buffer, __prev)
 MUTEX_FUTEX		offsetof (pthread_mutex_t, __data.__lock)
 POINTER_GUARD		offsetof (tcbhead_t, pointer_guard)
+FEATURE_1_OFFSET	offsetof (tcbhead_t, feature_1)
diff --git a/sysdeps/i386/nptl/tls.h b/sysdeps/i386/nptl/tls.h
index afb71ce431..21e23cd809 100644
--- a/sysdeps/i386/nptl/tls.h
+++ b/sysdeps/i386/nptl/tls.h
@@ -41,7 +41,10 @@ typedef struct
   uintptr_t stack_guard;
   uintptr_t pointer_guard;
   int gscope_flag;
-  int __glibc_reserved1;
+  /* Bit 0: X86_FEATURE_1_IBT.
+     Bit 1: X86_FEATURE_1_SHSTK.
+   */
+  unsigned int feature_1;
   /* Reservation of some values for the TM ABI.  */
   void *__private_tm[3];
   /* GCC split stack support.  */
diff --git a/sysdeps/x86/nptl/tls-setup.h b/sysdeps/x86/nptl/tls-setup.h
new file mode 100644
index 0000000000..ef5a4df78c
--- /dev/null
+++ b/sysdeps/x86/nptl/tls-setup.h
@@ -0,0 +1,23 @@
+/* Definitions to set up thread-local data.  x86 version.
+   Copyright (C) 2018 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/>.  */
+
+static inline void __attribute__ ((always_inline))
+tls_setup_tcbhead (struct pthread *pd)
+{
+  pd->header.feature_1 = THREAD_GETMEM (THREAD_SELF, header.feature_1);
+}
diff --git a/sysdeps/x86/sysdep.h b/sysdeps/x86/sysdep.h
index afcb7cfd76..976566aa37 100644
--- a/sysdeps/x86/sysdep.h
+++ b/sysdeps/x86/sysdep.h
@@ -21,6 +21,33 @@
 
 #include <sysdeps/generic/sysdep.h>
 
+/* __CET__ is defined by GCC with Control-Flow Protection values:
+
+enum cf_protection_level
+{
+  CF_NONE = 0,
+  CF_BRANCH = 1 << 0,
+  CF_RETURN = 1 << 1,
+  CF_FULL = CF_BRANCH | CF_RETURN,
+  CF_SET = 1 << 2
+};
+*/
+
+/* Set if CF_BRANCH (IBT) is enabled.  */
+#define X86_FEATURE_1_IBT	(1U << 0)
+/* Set if CF_RETURN (SHSTK) is enabled.  */
+#define X86_FEATURE_1_SHSTK	(1U << 1)
+
+#ifdef __CET__
+# define CET_ENABLED	1
+# define IBT_ENABLED	(__CET__ & X86_FEATURE_1_IBT)
+# define SHSTK_ENABLED	(__CET__ & X86_FEATURE_1_SHSTK)
+#else
+# define CET_ENABLED	0
+# define IBT_ENABLED	0
+# define SHSTK_ENABLED	0
+#endif
+
 #ifdef	__ASSEMBLER__
 
 /* Syntactic details of assembler.  */
diff --git a/sysdeps/x86_64/nptl/tcb-offsets.sym b/sysdeps/x86_64/nptl/tcb-offsets.sym
index be63404a16..387621e88c 100644
--- a/sysdeps/x86_64/nptl/tcb-offsets.sym
+++ b/sysdeps/x86_64/nptl/tcb-offsets.sym
@@ -12,6 +12,7 @@ MUTEX_FUTEX		offsetof (pthread_mutex_t, __data.__lock)
 MULTIPLE_THREADS_OFFSET	offsetof (tcbhead_t, multiple_threads)
 POINTER_GUARD		offsetof (tcbhead_t, pointer_guard)
 VGETCPU_CACHE_OFFSET	offsetof (tcbhead_t, vgetcpu_cache)
+FEATURE_1_OFFSET	offsetof (tcbhead_t, feature_1)
 
 -- Not strictly offsets, but these values are also used in the TCB.
 TCB_CANCELSTATE_BITMASK	 CANCELSTATE_BITMASK
diff --git a/sysdeps/x86_64/nptl/tls.h b/sysdeps/x86_64/nptl/tls.h
index 65c0051dcf..f042a0250a 100644
--- a/sysdeps/x86_64/nptl/tls.h
+++ b/sysdeps/x86_64/nptl/tls.h
@@ -51,7 +51,10 @@ typedef struct
   uintptr_t stack_guard;
   uintptr_t pointer_guard;
   unsigned long int vgetcpu_cache[2];
-  int __glibc_reserved1;
+  /* Bit 0: X86_FEATURE_1_IBT.
+     Bit 1: X86_FEATURE_1_SHSTK.
+   */
+  unsigned int feature_1;
   int __glibc_unused1;
   /* Reservation of some values for the TM ABI.  */
   void *__private_tm[4];