Introduce <pointer_guard.h>, extracted from <sysdep.h>

This allows us to define a generic no-op version of PTR_MANGLE and
PTR_DEMANGLE.  In the future, we can use PTR_MANGLE and PTR_DEMANGLE
unconditionally in C sources, avoiding an unintended loss of hardening
due to missing include files or unlucky header inclusion ordering.

In i386 and x86_64, we can avoid a <tls.h> dependency in the C
code by using the computed constant from <tcb-offsets.h>.  <sysdep.h>
no longer includes these definitions, so there is no cyclic dependency
anymore when computing the <tcb-offsets.h> constants.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

2 files changed, 68 insertions, 46 deletions

diff --git a/sysdeps/unix/sysv/linux/csky/pointer_guard.h b/sysdeps/unix/sysv/linux/csky/pointer_guard.h
new file mode 100644
index 0000000..ed68322
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/csky/pointer_guard.h
@@ -0,0 +1,68 @@
+/* Pointer obfuscation implenentation.  C-SKY version.
+   Copyright (C) 2022 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 POINTER_GUARD_H
+#define POINTER_GUARD_H
+
+#if (IS_IN (rtld) \
+     || (!defined SHARED && (IS_IN (libc) || IS_IN (libpthread))))
+# ifdef __ASSEMBLER__
+#  define PTR_MANGLE(dst, src, guard)                   \
+        grs     t0, 1f;                                 \
+1:                                                      \
+        lrw     guard, 1b@GOTPC;                        \
+        addu    t0, guard;                              \
+        lrw     guard, __pointer_chk_guard_local@GOT;   \
+        ldr.w   guard, (t0, guard << 0);                \
+        ldw     guard, (guard, 0);                      \
+        xor     dst, src, guard;
+#  define PTR_DEMANGLE(dst, src, guard) PTR_MANGLE (dst, src, guard)
+#  define PTR_MANGLE2(dst, src, guard) \
+        xor     dst, src, guard
+#  define PTR_DEMANGLE2(dst, src, guard) PTR_MANGLE2 (dst, src, guard)
+# else
+extern uintptr_t __pointer_chk_guard_local;
+#  define PTR_MANGLE(var) \
+  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
+#  define PTR_DEMANGLE(var) PTR_MANGLE (var)
+# endif
+#else
+# ifdef __ASSEMBLER__
+#  define PTR_MANGLE(dst, src, guard)           \
+        grs     t0, 1f;                         \
+1:                                              \
+        lrw     guard, 1b@GOTPC;                \
+        addu    t0, guard;                      \
+        lrw     guard, __pointer_chk_guard@GOT; \
+        ldr.w   guard, (t0, guard << 0);        \
+        ldw     guard, (guard, 0);              \
+        xor     dst, src, guard;
+#  define PTR_DEMANGLE(dst, src, guard) PTR_MANGLE (dst, src, guard)
+#  define PTR_MANGLE2(dst, src, guard) \
+        xor     dst, src, guard
+#  define PTR_DEMANGLE2(dst, src, guard) PTR_MANGLE2 (dst, src, guard)
+# else
+# include <stdint.h>
+extern uintptr_t __pointer_chk_guard;
+#  define PTR_MANGLE(var) \
+  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
+#  define PTR_DEMANGLE(var) PTR_MANGLE (var)
+# endif
+#endif
+
+#endif /* POINTER_GUARD_H */
diff --git a/sysdeps/unix/sysv/linux/csky/sysdep.h b/sysdeps/unix/sysv/linux/csky/sysdep.h
index 56c527f..76b09f0 100644
--- a/sysdeps/unix/sysv/linux/csky/sysdep.h
+++ b/sysdeps/unix/sysv/linux/csky/sysdep.h
@@ -466,50 +466,4 @@ __local_syscall_error:				\
 
 #endif /* __ASSEMBLER__ */
 
-/* Pointer mangling support.  */
-#if (IS_IN (rtld) \
-     || (!defined SHARED && (IS_IN (libc) || IS_IN (libpthread))))
-# ifdef __ASSEMBLER__
-#  define PTR_MANGLE(dst, src, guard)			\
-	grs	t0, 1f;					\
-1:							\
-	lrw	guard, 1b@GOTPC;			\
-	addu	t0, guard;				\
-	lrw	guard, __pointer_chk_guard_local@GOT;	\
-	ldr.w	guard, (t0, guard << 0);		\
-	ldw	guard, (guard, 0);			\
-	xor	dst, src, guard;
-#  define PTR_DEMANGLE(dst, src, guard) PTR_MANGLE (dst, src, guard)
-#  define PTR_MANGLE2(dst, src, guard) \
-	xor	dst, src, guard
-#  define PTR_DEMANGLE2(dst, src, guard) PTR_MANGLE2 (dst, src, guard)
-# else
-extern uintptr_t __pointer_chk_guard_local;
-#  define PTR_MANGLE(var) \
-  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard_local)
-#  define PTR_DEMANGLE(var) PTR_MANGLE (var)
-# endif
-#else
-# ifdef __ASSEMBLER__
-#  define PTR_MANGLE(dst, src, guard)		\
-	grs	t0, 1f;				\
-1:						\
-	lrw	guard, 1b@GOTPC;		\
-	addu	t0, guard;			\
-	lrw	guard, __pointer_chk_guard@GOT;	\
-	ldr.w	guard, (t0, guard << 0);	\
-	ldw	guard, (guard, 0);		\
-	xor	dst, src, guard;
-#  define PTR_DEMANGLE(dst, src, guard) PTR_MANGLE (dst, src, guard)
-#  define PTR_MANGLE2(dst, src, guard) \
-	xor	dst, src, guard
-#  define PTR_DEMANGLE2(dst, src, guard) PTR_MANGLE2 (dst, src, guard)
-# else
-extern uintptr_t __pointer_chk_guard;
-#  define PTR_MANGLE(var) \
-  (var) = (__typeof (var)) ((uintptr_t) (var) ^ __pointer_chk_guard)
-#  define PTR_DEMANGLE(var) PTR_MANGLE (var)
-# endif
-#endif
-
 #endif /* linux/csky/sysdep.h */