asm-generic: introduce asm/bitsperlong.h

This provides a reliable way for asm-generic/types.h and other
files to find out if it is running on a 32 or 64 bit platform.

We cannot use CONFIG_64BIT for this in headers that are included
from user space because CONFIG symbols are not available there.
We also cannot do it inside of asm/types.h because some headers
need the word size but cannot include types.h.

The solution is to introduce a new header <asm/bitsperlong.h>
that defines both __BITS_PER_LONG for user space and
BITS_PER_LONG for usage in the kernel. The asm-generic
version falls back to 32 bit unless the architecture overrides
it, which I did for all 64 bit platforms.

Signed-off-by: Remis Lima Baima <remis.developer@googlemail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

5 files changed, 38 insertions, 0 deletions

diff --git a/include/asm-generic/Kbuild b/include/asm-generic/Kbuild
index 460b08d..cbb4378 100644
--- a/include/asm-generic/Kbuild
+++ b/include/asm-generic/Kbuild
@@ -1,3 +1,4 @@
+header-y += bitsperlong.h
 header-y += errno-base.h
 header-y += errno.h
 header-y += fcntl.h
diff --git a/include/asm-generic/Kbuild.asm b/include/asm-generic/Kbuild.asm
index 70d1855..290910e 100644
--- a/include/asm-generic/Kbuild.asm
+++ b/include/asm-generic/Kbuild.asm
@@ -9,6 +9,7 @@ unifdef-y += a.out.h
 endif
 unifdef-y += auxvec.h
 unifdef-y += byteorder.h
+unifdef-y += bitsperlong.h
 unifdef-y += errno.h
 unifdef-y += fcntl.h
 unifdef-y += ioctl.h
diff --git a/include/asm-generic/bitsperlong.h b/include/asm-generic/bitsperlong.h
new file mode 100644
index 0000000..4ae54e0
--- /dev/null
+++ b/include/asm-generic/bitsperlong.h
@@ -0,0 +1,32 @@
+#ifndef __ASM_GENERIC_BITS_PER_LONG
+#define __ASM_GENERIC_BITS_PER_LONG
+
+/*
+ * There seems to be no way of detecting this automatically from user
+ * space, so 64 bit architectures should override this in their
+ * bitsperlong.h. In particular, an architecture that supports
+ * both 32 and 64 bit user space must not rely on CONFIG_64BIT
+ * to decide it, but rather check a compiler provided macro.
+ */
+#ifndef __BITS_PER_LONG
+#define __BITS_PER_LONG 32
+#endif
+
+#ifdef __KERNEL__
+
+#ifdef CONFIG_64BIT
+#define BITS_PER_LONG 64
+#else
+#define BITS_PER_LONG 32
+#endif /* CONFIG_64BIT */
+
+/*
+ * FIXME: The check currently breaks x86-64 build, so it's
+ * temporarily disabled. Please fix x86-64 and reenable
+ */
+#if 0 && BITS_PER_LONG != __BITS_PER_LONG
+#error Inconsistent word size. Check asm/bitsperlong.h
+#endif
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_GENERIC_BITS_PER_LONG */
diff --git a/include/asm-generic/int-l64.h b/include/asm-generic/int-l64.h
index 2af9b75..1ca3efc 100644
--- a/include/asm-generic/int-l64.h
+++ b/include/asm-generic/int-l64.h
@@ -8,6 +8,8 @@
 #ifndef _ASM_GENERIC_INT_L64_H
 #define _ASM_GENERIC_INT_L64_H
 
+#include <asm/bitsperlong.h>
+
 #ifndef __ASSEMBLY__
 /*
  * __xx is ok: it doesn't pollute the POSIX namespace. Use these in the
diff --git a/include/asm-generic/int-ll64.h b/include/asm-generic/int-ll64.h
index f9bc9ac..f394147 100644
--- a/include/asm-generic/int-ll64.h
+++ b/include/asm-generic/int-ll64.h
@@ -8,6 +8,8 @@
 #ifndef _ASM_GENERIC_INT_LL64_H
 #define _ASM_GENERIC_INT_LL64_H
 
+#include <asm/bitsperlong.h>
+
 #ifndef __ASSEMBLY__
 /*
  * __xx is ok: it doesn't pollute the POSIX namespace. Use these in the