[v2] powerpc/lib/sstep: Fix count leading zeros instructions

[Michael Ellerman]

On Tue, 2017-10-10 at 06:45:30 UTC, Sandipan Das wrote:
> According to the GCC documentation, the behaviour of __builtin_clz()
> and __builtin_clzl() is undefined if the value of the input argument
> is zero. Without handling this special case, these builtins have been
> used for emulating the following instructions:
>   * Count Leading Zeros Word (cntlzw[.])
>   * Count Leading Zeros Doubleword (cntlzd[.])
> 
> This fixes the emulated behaviour of these instructions by adding an
> additional check for this special case.
> 
> Fixes: 3cdfcbfd32b9d ("powerpc: Change analyse_instr so it doesn't modify *regs")
> Signed-off-by: Sandipan Das <sandipan at linux.vnet.ibm.com>
> Reviewed-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/b0490a04e736356e427e227902b17f

cheers