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Re: [PATCH v2] signals, pkeys: make si_pkey 32 bits

From Ingo Molnar <mingo@kernel.org>
Newsgroups linux.kernel
Subject Re: [PATCH v2] signals, pkeys: make si_pkey 32 bits
Date 2016-02-29 09:00 +0100
Message-ID <r7qUi-69-7@gated-at.bofh.it> (permalink)
References (3 earlier) <r6LxL-2kH-1@gated-at.bofh.it> <r6Szf-7Cl-1@gated-at.bofh.it> <r6SSC-7LP-11@gated-at.bofh.it> <r6Wtc-1Rk-3@gated-at.bofh.it> <r6WMy-1YM-5@gated-at.bofh.it>
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* Stephen Rothwell <sfr@canb.auug.org.au> wrote:

> In order to prevent a change of alignment of the _sifields union in the
> siginfo structure on (some) 32 bit platforms and an ABI breakage, we
> change the type of _pkey to unsigned int.  If more bits are needed in
> the future, a second unsigned int could be added.
> 
> Fixes: cd0ea35ff551 ("signals, pkeys: Notify userspace about protection key faults")
> Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
> ---
>  arch/ia64/include/uapi/asm/siginfo.h | 2 +-
>  arch/mips/include/uapi/asm/siginfo.h | 2 +-
>  include/uapi/asm-generic/siginfo.h   | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/ia64/include/uapi/asm/siginfo.h b/arch/ia64/include/uapi/asm/siginfo.h
> index 0151cfab929d..19e7db0c9453 100644
> --- a/arch/ia64/include/uapi/asm/siginfo.h
> +++ b/arch/ia64/include/uapi/asm/siginfo.h
> @@ -70,7 +70,7 @@ typedef struct siginfo {
>  					void __user *_upper;
>  				} _addr_bnd;
>  				/* used when si_code=SEGV_PKUERR */
> -				u64 _pkey;
> +				unsigned int _pkey;
>  			};
>  		} _sigfault;
>  
> diff --git a/arch/mips/include/uapi/asm/siginfo.h b/arch/mips/include/uapi/asm/siginfo.h
> index 6f4edf0d794c..3cc14f4a5936 100644
> --- a/arch/mips/include/uapi/asm/siginfo.h
> +++ b/arch/mips/include/uapi/asm/siginfo.h
> @@ -93,7 +93,7 @@ typedef struct siginfo {
>  					void __user *_upper;
>  				} _addr_bnd;
>  				/* used when si_code=SEGV_PKUERR */
> -				u64 _pkey;
> +				unsigned int _pkey;
>  			};
>  		} _sigfault;
>  
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index 90384d55225b..f4459dc3d31b 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -98,7 +98,7 @@ typedef struct siginfo {
>  					void __user *_upper;
>  				} _addr_bnd;
>  				/* used when si_code=SEGV_PKUERR */
> -				u64 _pkey;
> +				unsigned int _pkey;
>  			};
>  		} _sigfault;
>  

Please use the standard ABI integer type pattern: __u32.

The advantage of only using __[su][8|16|32|64] integer types is that it's 
"obvious" at a glance that an ABI is bitness-invariant.

For example include/uapi/linux/perf_event.h only uses such ABI-safe types, and 
arch/x86/include/uapi is using these types 95%+ of the time.

( The various struct siginfo definitions should probably be harmonized as well, 
  but in a separate patch. )

Thanks,

	Ingo

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Thread

[PATCH] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen <dave@sr71.net> - 2016-02-26 18:40 +0100
  Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field "H. Peter Anvin" <hpa@zytor.com> - 2016-02-26 18:50 +0100
    Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-26 23:20 +0100
      Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Ingo Molnar <mingo@kernel.org> - 2016-02-27 12:50 +0100
        Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Dave Hansen <dave@sr71.net> - 2016-02-27 20:20 +0100
          Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field "H. Peter Anvin" <hpa@zytor.com> - 2016-02-27 20:40 +0100
            Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-28 00:30 +0100
              [PATCH v2] signals, pkeys: make si_pkey 32 bits Stephen Rothwell <sfr@canb.auug.org.au> - 2016-02-28 00:50 +0100
                Re: [PATCH v2] signals, pkeys: make si_pkey 32 bits Ingo Molnar <mingo@kernel.org> - 2016-02-29 09:00 +0100
              Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Ingo Molnar <mingo@kernel.org> - 2016-02-29 09:10 +0100
                Re: [PATCH] x86, pkeys: fix siginfo ABI breakage from new field Stephen Rothwell <sfr@canb.auug.org.au> - 2016-03-01 00:00 +0100

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