Re: [Xen-devel] [PATCH v3 1/8] arm: put types.h in uapi

2017-01-13 Thread Russell King - ARM Linux 
On Fri, Jan 13, 2017 at 11:46:39AM +0100, Nicolas Dichtel wrote:
> This header file is exported, thus move it to uapi.

I'm taking this patch, but with the following commit log:

  Due to the way kbuild works, this header was unintentionally exported
  back in 2013 when it was created, despite it not being in a uapi/
  directory.  This is very non-intuitive behaviour by Kbuild.

  However, we've had this include exported to userland for almost four
  years, and searching google for "ARM types.h __UINTPTR_TYPE__" gives
  no hint that anyone has complained about it.  So, let's make it
  officially exported in this state.

If anyone has any objections, they better shout sooner rather than
later.

> 
> Signed-off-by: Nicolas Dichtel 
> ---
>  arch/arm/include/asm/types.h  | 40 
> ---
>  arch/arm/include/uapi/asm/types.h | 40 
> +++
>  2 files changed, 40 insertions(+), 40 deletions(-)
>  delete mode 100644 arch/arm/include/asm/types.h
>  create mode 100644 arch/arm/include/uapi/asm/types.h
> 
> diff --git a/arch/arm/include/asm/types.h b/arch/arm/include/asm/types.h
> deleted file mode 100644
> index a53cdb8f068c..
> --- a/arch/arm/include/asm/types.h
> +++ /dev/null
> @@ -1,40 +0,0 @@
> -#ifndef _ASM_TYPES_H
> -#define _ASM_TYPES_H
> -
> -#include 
> -
> -/*
> - * 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 longunsigned long  unsigned int
> - * 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 */
> diff --git a/arch/arm/include/uapi/asm/types.h 
> b/arch/arm/include/uapi/asm/types.h
> new file mode 100644
> index ..9435a42f575e
> --- /dev/null
> +++ b/arch/arm/include/uapi/asm/types.h
> @@ -0,0 +1,40 @@
> +#ifndef _UAPI_ASM_TYPES_H
> +#define _UAPI_ASM_TYPES_H
> +
> +#include 
> +
> +/*
> + * 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 longunsigned long  unsigned int
> + * 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 /* _UAPI_ASM_TYPES_H */
> -- 
> 2.8.1
> 

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Re: [Xen-devel] [PATCH v3 1/8] arm: put types.h in uapi

2017-01-13 Thread Russell King - ARM Linux 
On Fri, Jan 13, 2017 at 05:01:01PM +0100, Nicolas Dichtel wrote:
> Please, do not remove the email subject when you reply. I restore it to
> ease the thread follow-up.

I mentioned it to David, and he says it's because the long list of
recipients is breaking his mailer.  I've already posed the question
about whether that's exploitable!

> Le 13/01/2017 à 16:36, David Howells a écrit :
> > Nicolas Dichtel  wrote:
> > 
> >> This header file is exported, thus move it to uapi.
> > 
> > Exported how?
> 
> It is listed in include/uapi/asm-generic/Kbuild.asm, which is included by
> arch/arm/include/uapi/asm/Kbuild.

We really should not be installing non-uapi header files to userland
under _any_ circumstance - this to me sounds like a bug in kbuild.

The assumption is that headers outside of uapi directories are not
part of the user visible API, and so can be freely modified - which
in the presence of this bug is untrue.

However, as it's happening, and this header has been there since 2013
(commit 09096f6a0ee2 - "ARM: 7822/1: add workaround for ambiguous C99
stdint.h types") it's now well and truely part of the user API whether
we intended it to be or not, so your patch looks to me like the correct
thing to do.

I think it needs further evaluation to make sure kbuild isn't going to
do something else silly, like subsitute include/asm-generic/types.h for
the now missing arch/arm/include/asm/types.h

I wonder how many more headers are unintentionally exported.

... what a mess. :(

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

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Re: [Xen-devel] [PATCH v3 1/8] arm: put types.h in uapi

2017-01-13 Thread Nicolas Dichtel 
Please, do not remove the email subject when you reply. I restore it to ease the
thread follow-up.

Le 13/01/2017 à 16:36, David Howells a écrit :
> Nicolas Dichtel  wrote:
> 
>> This header file is exported, thus move it to uapi.
> 
> Exported how?
It is listed in include/uapi/asm-generic/Kbuild.asm, which is included by
arch/arm/include/uapi/asm/Kbuild.

You can also have a look at patch #5 to see why it was exported even if it was
not in an uapi directory.

Regards,
Nicolas

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