clang doesn't propagate attributes like "asm labels" and "visibility(hidden)"

to builtins like mem{set,cpy,move} and __stack_smash_handler.  So, when
building with clang, instead mark those as protected visibility to get rid
of the PLT relocations.  We can't take the address of them then, but that's
ok: it's a build-time error not a run-time error.

ok kettenis@

4 files changed, 23 insertions, 11 deletions

diff --git a/src/lib/libc/include/namespace.h b/src/lib/libc/include/namespace.h
index 980c1a8dd6..73b845e10f 100644
--- a/src/lib/libc/include/namespace.h
+++ b/src/lib/libc/include/namespace.h
@@ -1,4 +1,4 @@
-/*      $OpenBSD: namespace.h,v 1.10 2016/05/07 19:05:22 guenther Exp $ */
+/*      $OpenBSD: namespace.h,v 1.11 2017/11/29 05:13:57 guenther Exp $ */
 
 #ifndef _LIBC_NAMESPACE_H_
 #define _LIBC_NAMESPACE_H_
@@ -154,23 +154,35 @@
 #define DEF_CANCEL(x)           __weak_alias(x, CANCEL(x))
 #define DEF_WRAP(x)             __weak_alias(x, WRAP(x))
 #define DEF_SYS(x)              __strong_alias(_thread_sys_##x, HIDDEN(x))
+#ifdef __clang__
+#define DEF_BUILTIN(x)          __asm("")
+#define BUILTIN                 __attribute__((__visibility__("protected")))
+#else
+#define DEF_BUILTIN(x)          DEF_STRONG(x)
+#define BUILTIN
+#endif
 
 #define MAKE_CLONE(dst, src)    __dso_hidden typeof(dst) HIDDEN(dst) \
                                 __attribute__((alias (HIDDEN_STRING(src))))
 
 
 /*
- * gcc will generate calls to the functions below.
+ * gcc and clang will generate calls to the functions below.
  * Declare and redirect them here so we always go
  * directly to our hidden aliases.
  */
 #include <sys/_types.h>
-void    *memcpy(void *__restrict, const void *__restrict, __size_t);
-void    *memset(void *, int, __size_t);
-void    __stack_smash_handler(const char [], int __attribute__((__unused__)));
+BUILTIN void    *memmove(void *, const void *, __size_t);
+BUILTIN void    *memcpy(void *__restrict, const void *__restrict, __size_t);
+BUILTIN void    *memset(void *, int, __size_t);
+BUILTIN void    __stack_smash_handler(const char [], int __unused);
+#ifndef __clang__
+PROTO_NORMAL(memmove);
 PROTO_NORMAL(memcpy);
 PROTO_NORMAL(memset);
 PROTO_NORMAL(__stack_smash_handler);
+#endif
+#undef  BUILTIN
 
 #endif  /* _LIBC_NAMESPACE_H_ */
 
diff --git a/src/lib/libc/string/memcpy.c b/src/lib/libc/string/memcpy.c
index a2516ed041..19fddc0ab5 100644
--- a/src/lib/libc/string/memcpy.c
+++ b/src/lib/libc/string/memcpy.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: memcpy.c,v 1.3 2017/08/14 17:10:02 guenther Exp $ */
+/*      $OpenBSD: memcpy.c,v 1.4 2017/11/29 05:13:57 guenther Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -106,4 +106,4 @@ memcpy(void *dst0, const void *src0, size_t length)
 done:
         return (dst0);
 }
-DEF_STRONG(memcpy);
+DEF_BUILTIN(memcpy);
diff --git a/src/lib/libc/string/memmove.c b/src/lib/libc/string/memmove.c
index 2f1deb2c70..1cd1086ab9 100644
--- a/src/lib/libc/string/memmove.c
+++ b/src/lib/libc/string/memmove.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: memmove.c,v 1.2 2015/08/31 02:53:57 guenther Exp $ */
+/*      $OpenBSD: memmove.c,v 1.3 2017/11/29 05:13:57 guenther Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -110,4 +110,4 @@ memmove(void *dst0, const void *src0, size_t length)
 done:
         return (dst0);
 }
-DEF_STRONG(memmove);
+DEF_BUILTIN(memmove);
diff --git a/src/lib/libc/string/memset.c b/src/lib/libc/string/memset.c
index 242529ee0f..0c261f0965 100644
--- a/src/lib/libc/string/memset.c
+++ b/src/lib/libc/string/memset.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: memset.c,v 1.7 2015/08/31 02:53:57 guenther Exp $ */
+/*      $OpenBSD: memset.c,v 1.8 2017/11/29 05:13:57 guenther Exp $ */
 /*-
  * Copyright (c) 1990 The Regents of the University of California.
  * All rights reserved.
@@ -45,4 +45,4 @@ memset(void *dst, int c, size_t n)
         }
         return (dst);
 }
-DEF_STRONG(memset);
+DEF_BUILTIN(memset);