Update Linux kernel to current glibc soft-fp

[Joseph Myers]

On Thu, 26 Mar 2015, Stefan Liebler wrote:

> According to "error: lvalue required as left operand of assignment":
> Why did you write back r in include/math-emu/op-common.h:
> #define _FP_FROM_INT(fs, wc, X, r, rsize, rtype):
> 	  if ((X##_s = ((r) < 0)))
> 	    (r) = -(rtype) (r);
> 	  _FP_FROM_INT_ur = (rtype) (r);

Because the _FP_FROM_INT interface requires an argument of the correct 
signedness, but needs to work internally on an unsigned value, so starts 
by negating a signed argument.

> @@ -435,11 +436,12 @@ void s390_adjust_jiffies(void)
>  		 * by the cpu capability number. Yes, that means a floating
>  		 * point division .. math-emu here we come :-)
>  		 */
> -		FP_UNPACK_SP(SA, &fmil);
> -		if ((info->capability >> 23) == 0)
> -			FP_FROM_INT_S(SB, (long) info->capability, 64, long);
> -		else
> -			FP_UNPACK_SP(SB, &info->capability);
> +		FP_UNPACK_SEMIRAW_SP(SA, &fmil);
> +		if ((info->capability >> 23) == 0) {
> +			unsigned long r = info->capability;
> +			FP_FROM_INT_S(SB, r, 64, unsigned long);
> +		} else
> +			FP_UNPACK_SEMIRAW_SP(SB, &info->capability);
>  		FP_DIV_S(SR, SA, SB);
>  		FP_TO_INT_S(capability, SR, 32, 0);

Division uses cooked inputs and outputs.  FP_TO_INT uses raw inputs.  
FP_FROM_INT uses raw outputs.

So for unpacking SA you should continue to use FP_UNPACK_SP, as the result 
goes straight into division.  For unpacking SB, it seems appropriate to 
use FP_UNPACK_RAW_SP.  Then, after either unpacking or FP_FROM_INT_S, you 
have a raw value in SB, and can use _FP_UNPACK_CANONICAL to produce a 
cooked value from it that can be used as an input to the division.

As for the integer argument to FP_FROM_INT_S, the existing code treats it 
as signed long, so the same semantics would be preserved by making the 
temporary variable of that type (however, you still need to pass "unsigned 
long" as the last argument to FP_FROM_INT_S, as it expects the type name 
passed to be the name of an unsigned type).

-- 
Joseph S. Myers
joseph@codesourcery.com