ARM: add workaround for ambiguous C99 stdint.h types

The C99 types uintXX_t that are usually defined in 'stdint.h' are not as unambiguous on ARM as you would expect. For the types below, there is a difference on ARM between GCC built for bare metal ARM, GCC built for glibc and the kernel itself, which results in build errors if you try to build with -ffreestanding and include 'stdint.h' (such as when you include 'arm_neon.h' in order to use NEON intrinsics)

As the typedefs for these types in 'stdint.h' are based on builtin defines supplied by GCC, we can tweak these to align with the kernel's idea of those types, so 'linux/types.h' and 'stdint.h' can be safely included from the same source file (provided that -ffreestanding is used).

                   int32_t         uint32_t               uintptr_t
bare metal GCC     long            unsigned long          unsigned long
glibc GCC          int             unsigned int           unsigned int
kernel             int             unsigned int           unsigned long

Signed-off-by Ard Biesheuvel <[email protected]>

Acked-by Nicolas Pitre <[email protected]>

---

Hello Russell,

Would you please consider merging this patch?

It allows NEON intrinsics code to access kernel data structures (that typically depend on linux/types.h), avoiding the need for messy workarounds. No other kernel code uses these macros, so nothing else should be affected.

Regards,
Ard.

 arch/arm/include/asm/types.h | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 arch/arm/include/asm/types.h

arch/arm/include/asm/types.h new file +40 -0

new file mode 100644
index 0000000..c4f0bca
@@ -0,0 +1,40 @@
+#ifndef _ASM_TYPES_H
+#define _ASM_TYPES_H
+
+#include <asm-generic/int-ll64.h>
+
+/*
+ * The C99 types uintXX_t that are usually defined in 'stdint.h' are not as
+ * unambiguous on ARM as you would expect. For the types below, there is a
+ * difference on ARM between GCC built for bare metal ARM, GCC built for glibc
+ * and the kernel itself, which results in build errors if you try to build with
+ * -ffreestanding and include 'stdint.h' (such as when you include 'arm_neon.h'
+ * in order to use NEON intrinsics)
+ *
+ * As the typedefs for these types in 'stdint.h' are based on builtin defines
+ * supplied by GCC, we can tweak these to align with the kernel's idea of those
+ * types, so 'linux/types.h' and 'stdint.h' can be safely included from the same
+ * source file (provided that -ffreestanding is used).
+ * 
+ *                    int32_t         uint32_t               uintptr_t
+ * bare metal GCC     long            unsigned long          unsigned long
+ * glibc GCC          int             unsigned int           unsigned int
+ * kernel             int             unsigned int           unsigned long
+ */
+
+#ifdef __INT32_TYPE__
+#undef __INT32_TYPE__
+#define __INT32_TYPE__		int
+#endif
+
+#ifdef __UINT32_TYPE__
+#undef __UINT32_TYPE__
+#define __UINT32_TYPE__	unsigned int
+#endif
+
+#ifdef __UINTPTR_TYPE__
+#undef __UINTPTR_TYPE__
+#define __UINTPTR_TYPE__	unsigned long
+#endif
+
+#endif /* _ASM_TYPES_H */

Signature · 7 lines

1.8.1.2


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

The C99 types uintXX_t that are usually defined in 'stdint.h' are not as unambiguous on ARM as you would expect. For the types below, there is a difference on ARM between GCC built for bare metal ARM, GCC built for glibc and the kernel itself, which results in build errors if you try to build with -ffreestanding and include 'stdint.h' (such as when you include 'arm_neon.h' in order to use NEON intrinsics)