Petr Vandrovec wrote:
> Yes. You can even:
> ...
> i = copy_from_user(arg, kernel, PAGE_SIZE);
> if (i == PAGE_SIZE) {
> for (i = 0; i < PAGE_SIZE; i++)
> if (get_user(arg++, kernel++))
> break;
> i = PAGE_SIZE - i;
> }
> if (i)
> memset(kernel + PAGE_SIZE - i, 0, i);
> ...
> If parameter is not in the top 4KB of user memory, task will be done
> with fast copy_from_user. Only if it completely fails (either completely
> bogus pointer or end-of-user memory problem), code will switch into
> byte-by-byte copy. Of course, such thing requires comment in source
> so that nobody will remove it again :-)
No need to reinvent the wheel... just take a look at do_getname().
--Brian Gerst
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