arm: move check for BX to its own header

As Will noticed, the header this check is currently done in
is asm-only, and is not meant to be included from C code.
This breaks compilation when compiled for a Thumb2-aware CPU.

Move the BX check to its own header, and revert 7a246fd.

Reported-by: Will Newton <will.newton@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Will Newton <will.newton@gmail.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

ldso/ldso/arm/dl-startup.h

@@ -7,7 +7,7 @@
  */
 
 #include <features.h>
-#include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #if !defined(__thumb__)
 __asm__(

ldso/ldso/arm/resolve.S

@@ -92,6 +92,7 @@
 
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #include <features.h>
 

libc/string/arm/_memcpy.S

@@ -40,6 +40,7 @@
 #include <features.h>
 #include <endian.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #if !defined(THUMB1_ONLY)
 /*

libc/string/arm/memcmp.S

@@ -31,6 +31,7 @@
 
 #include <features.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 .text
 .global memcmp

libc/string/arm/memset.S

@@ -19,6 +19,7 @@
 #include <features.h>
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 .text
 .global memset

libc/string/arm/strcmp.S

@@ -31,6 +31,7 @@
 
 #include <features.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 .text
 .global strcmp

libc/string/arm/strlen.S

@@ -20,6 +20,7 @@
 #include <endian.h>
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 /* size_t strlen(const char *S)
  * entry: r0 -> string

libc/sysdeps/linux/arm/__longjmp.S

@@ -18,6 +18,7 @@
 
 #include <features.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 .global __longjmp
 .type __longjmp,%function

libc/sysdeps/linux/arm/bits/arm_asm.h

@@ -26,12 +26,4 @@
 #define THUMB1_ONLY 1
 #endif
 
-#if defined(__USE_BX__)
-# if (   defined (__ARM_ARCH_2__)  || defined (__ARM_ARCH_3__) \
-      || defined (__ARM_ARCH_3M__) || defined (__ARM_ARCH_4__) \
-     )
-#  error Use of BX was requested, but is not available on the target processor.
-# endif /* ARCH level */
-#endif /* __USE_BX__ */
-
 #endif /* _ARM_ASM_H */

libc/sysdeps/linux/arm/bits/arm_bx.h

@@ -0,0 +1,34 @@
+/* Copyright (C) 2013 Yann E. MORIN <yann.morin.1998@free.fr>
+ *
+ * This file 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.
+ *
+ * This file 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/>.
+ */
+
+#ifndef _ARM_BX_H
+#define _ARM_BX_H
+
+/* We need features.h first */
+#if !defined _FEATURES_H
+#error Please include features.h first
+#endif /* features.h not yet included */
+
+#if defined(__USE_BX__)
+# if (   defined (__ARM_ARCH_2__)  || defined (__ARM_ARCH_3__) \
+      || defined (__ARM_ARCH_3M__) || defined (__ARM_ARCH_4__) \
+     )
+#  error Use of BX was requested, but is not available on the target processor.
+# endif /* ARCH level */
+#endif /* __USE_BX__ */
+
+#endif /* _ARM_BX_H */

libc/sysdeps/linux/arm/clone.S

@@ -24,6 +24,7 @@
 #include <bits/errno.h>
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #if defined(__NR_clone)
 /* int clone(int (*fn)(void *arg), void *child_stack, int flags, void *arg); */

libc/sysdeps/linux/arm/mmap64.S

@@ -20,6 +20,7 @@
 #include <bits/errno.h>
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #ifdef __NR_mmap2
 

libc/sysdeps/linux/arm/syscall-eabi.S

@@ -17,6 +17,7 @@
 
 #include <sys/syscall.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 /* In the EABI syscall interface, we don't need a special syscall to
    implement syscall().  It won't work reliably with 64-bit arguments

libc/sysdeps/linux/arm/sysdep.h

@@ -20,7 +20,7 @@
 #define _LINUX_ARM_SYSDEP_H 1
 
 #include <common/sysdep.h>
-#include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #include <sys/syscall.h>
 /* For Linux we can use the system call table in the header file

libc/sysdeps/linux/arm/vfork.S

@@ -7,6 +7,7 @@
 
 #include <features.h>
 #include <bits/arm_asm.h>
+#include <bits/arm_bx.h>
 
 #define _ERRNO_H
 #include <bits/errno.h>