On Thu, Jul 8, 2021 at 5:57 AM Christoph Hellwig <hch@xxxxxx> wrote:
I've force pushed a new version to the branch, can you give it a spin?
Please stop playing broken games with __constant_copy_to_user().
Now you didn't just break the return value, you broke the actual copy
too. When it is supposed to do a 4-byte copy, the code now does *two*
4-byte copies, because that's the way __constant_copy_to_user_asm()
works - it always does at least two accesses, and then the third one
is conditional.
So that "6, l, l, )" in
case 4:
__constant_copy_to_user_asm(res, to, from, tmp, 6, l, l,);
break;
literally means "try to do 2x 'l' sized moves (but not a third one),
and return 6 if it fails". All of which is very wrong indeed.
So commit d36105c942e0 ("m68k: simplify the __constant_copy_to_user
implementation") is very very broken.
But the rest looks good to me. Of course, I entirely missed the fact
that Andreas pointed out - "instr" was inside a string - so who knows
what I missed this time.
Linus
