Larry Finger writes:
> On 06/23/2017 03:29 PM, Al Viro wrote:
>> On Fri, Jun 23, 2017 at 01:49:16PM -0500, Larry Finger wrote:
>>
BTW, could you try to check what happens if you kill the
if (__builtin_constant_p(n) && (n <= 8))
bits in raw_copy_{to,from}_user()? The usefulness
Al Viro writes:
> On Sun, Jun 25, 2017 at 04:44:09PM -0500, Segher Boessenkool wrote:
>
>> Do you have a short stand-alone testcase? 4.6 is ancient, of course, but
>> the actual problem may still exist in more recent compilers (if it _is_
>> a compiler problem; if it's not, you *really* want to
On Sun, Jun 25, 2017 at 04:44:09PM -0500, Segher Boessenkool wrote:
> Do you have a short stand-alone testcase? 4.6 is ancient, of course, but
> the actual problem may still exist in more recent compilers (if it _is_
> a compiler problem; if it's not, you *really* want to know :-) )
Enjoy. At l
On Sun, Jun 25, 2017 at 09:53:24PM +0100, Al Viro wrote:
> Confirmed. It manages to bugger the loop immediately after the (successful)
> copying of iovec array in rw_copy_check_uvector(); both with and without
> INLINE_COPY_FROM_USER it has (just before the call of copy_from_user()) r27
> set to n
On Sun, Jun 25, 2017 at 12:14:04PM +0100, Al Viro wrote:
> On Sun, Jun 25, 2017 at 10:53:58AM +0100, Al Viro wrote:
> > On Sat, Jun 24, 2017 at 12:29:23PM -0500, Larry Finger wrote:
> >
> > > I made a break through. If I turn off inline copy to/from users for 32-bit
> > > ppc with the following pa
On Sun, Jun 25, 2017 at 10:53:58AM +0100, Al Viro wrote:
> On Sat, Jun 24, 2017 at 12:29:23PM -0500, Larry Finger wrote:
>
> > I made a break through. If I turn off inline copy to/from users for 32-bit
> > ppc with the following patch, then the system boots:
>
> OK... So it's 4.6.3 miscompiling
On Sat, Jun 24, 2017 at 12:29:23PM -0500, Larry Finger wrote:
> I made a break through. If I turn off inline copy to/from users for 32-bit
> ppc with the following patch, then the system boots:
OK... So it's 4.6.3 miscompiling something - it is hardware-independent,
reproduced in qemu. I'd like
On 06/23/2017 03:29 PM, Al Viro wrote:
On Fri, Jun 23, 2017 at 01:49:16PM -0500, Larry Finger wrote:
BTW, could you try to check what happens if you kill the
if (__builtin_constant_p(n) && (n <= 8))
bits in raw_copy_{to,from}_user()? The usefulness of those (in
__copy_from_user()
orig
On Fri, Jun 23, 2017 at 01:49:16PM -0500, Larry Finger wrote:
> > BTW, could you try to check what happens if you kill the
> > if (__builtin_constant_p(n) && (n <= 8))
> > bits in raw_copy_{to,from}_user()? The usefulness of those (in
> > __copy_from_user()
> > originally) had always been du