Re: [PATCH 01/12] x86_64: memset_user()

Igor Stoppa
2018-12-21T18:46:54Z

On 21/12/2018 20:25, Matthew Wilcox wrote:
> On Fri, Dec 21, 2018 at 08:14:12PM +0200, Igor Stoppa wrote:
>> +unsigned long __memset_user(void __user *addr, int c, unsigned long size)
>> +{
>> + long __d0;
>> + unsigned long pattern = 0;
>> + int i;
>> +
>> + for (i = 0; i < 8; i++)
>> + pattern = (pattern << 8) | (0xFF & c);
>
> That's inefficient.
>
> pattern = (unsigned char)c;
> pattern |= pattern << 8;
> pattern |= pattern << 16;
> pattern |= pattern << 32;

ok, thank you

--
igor