Make SH ucontext always match current kernels

As discussed in the thread starting at
<https://sourceware.org/ml/libc-alpha/2015-06/msg00657.html>, there
are various problems with the sigcontext / mcontext / ucontext
structures on SH.  The soft-float SH4 case in fact does not build at
present, with errors processing
sysdeps/unix/sysv/linux/sh/sh4/ucontext_i.sym with gen-as-const.awk
("error: 'mcontext_t {aka struct <anonymous>}' has no member named
'fpregs'").

Linux 4.8 (commit bbe6c77857c38f4acbdc4fc70399515226d1859a) moved to
always using the same sigcontext structure on SH, with room for
floating-point registers whether or not present on the processor.
This patch makes the glibc header match.

Tested (compilation only) for sh4-linux-gnu hard float, and in
conjunction with other fixes for soft float.

2016-11-07  Joseph Myers  <joseph@codesourcery.com>

	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h [__SH4__ || __SH4A__]:
	Make code unconditional.
	[!(__SH4__ || __SH4A__)]: Remove conditional code.

On Mon, Nov 07, 2016 at 11:18:32PM +0000, Joseph Myers wrote:
> As discussed in the thread starting at
> <https://sourceware.org/ml/libc-alpha/2015-06/msg00657.html>, there
> are various problems with the sigcontext / mcontext / ucontext
> structures on SH.  The soft-float SH4 case in fact does not build at
> present, with errors processing
> sysdeps/unix/sysv/linux/sh/sh4/ucontext_i.sym with gen-as-const.awk
> ("error: 'mcontext_t {aka struct <anonymous>}' has no member named
> 'fpregs'").
> 
> Linux 4.8 (commit bbe6c77857c38f4acbdc4fc70399515226d1859a) moved to
> always using the same sigcontext structure on SH, with room for
> floating-point registers whether or not present on the processor.
> This patch makes the glibc header match.
> 
> Tested (compilation only) for sh4-linux-gnu hard float, and in
> conjunction with other fixes for soft float.
> 
> 2016-11-07  Joseph Myers  <joseph@codesourcery.com>
> 
> 	* sysdeps/unix/sysv/linux/sh/sys/ucontext.h [__SH4__ || __SH4A__]:
> 	Make code unconditional.
> 	[!(__SH4__ || __SH4A__)]: Remove conditional code.
> 
> diff --git a/sysdeps/unix/sysv/linux/sh/sys/ucontext.h b/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
> index 2c5fa04..4ee0b28 100644
> --- a/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
> +++ b/sysdeps/unix/sysv/linux/sh/sys/ucontext.h
> @@ -76,7 +76,6 @@ enum
>  };
>  #endif
>  
> -#if (defined(__SH4__) || defined(__SH4A__))
>  typedef int freg_t;
>  
>  /* Number of FPU registers.  */
> @@ -102,20 +101,6 @@ typedef struct
>      unsigned int fpul;
>      unsigned int ownedfp;
>    } mcontext_t;
> -#else
> -/* Context to describe whole processor state.  */
> -typedef struct
> -  {
> -    unsigned int oldmask;
> -    gregset_t gregs;
> -    unsigned int pc;
> -    unsigned int pr;
> -    unsigned int sr;
> -    unsigned int gbr;
> -    unsigned int mach;
> -    unsigned int macl;
> -  } mcontext_t;
> -#endif /* __SH_FPU_ANY__ */
>  
>  /* Userlevel context.  */
>  typedef struct ucontext

I haven't tested the patch, but it looks like the change I
expected/hoped to see glibc make when working on the kernel side.
Thanks.

Rich

Ping.  This patch 
<https://sourceware.org/ml/libc-alpha/2016-11/msg00256.html> is pending 
review.

On 07 Nov 2016 23:18, Joseph Myers wrote:
> As discussed in the thread starting at
> <https://sourceware.org/ml/libc-alpha/2015-06/msg00657.html>, there
> are various problems with the sigcontext / mcontext / ucontext
> structures on SH.  The soft-float SH4 case in fact does not build at
> present, with errors processing
> sysdeps/unix/sysv/linux/sh/sh4/ucontext_i.sym with gen-as-const.awk
> ("error: 'mcontext_t {aka struct <anonymous>}' has no member named
> 'fpregs'").
> 
> Linux 4.8 (commit bbe6c77857c38f4acbdc4fc70399515226d1859a) moved to
> always using the same sigcontext structure on SH, with room for
> floating-point registers whether or not present on the processor.
> This patch makes the glibc header match.
> 
> Tested (compilation only) for sh4-linux-gnu hard float, and in
> conjunction with other fixes for soft float.

lgtm
-mike