On Wed, Dec 07, 2022 at 03:21:04PM +0300, Dan Carpenter wrote:
> On Wed, Dec 07, 2022 at 02:19:36PM +0200, Vladimir Oltean wrote:
> > On Wed, Dec 07, 2022 at 02:23:28PM +0300, Dan Carpenter wrote:
> > > The bit_reverse() function is clearly supposed to be able to handle
> > > 64 bit values, but the types for "(1 << i)" and "bit << (width - i - 1)"
> > > are not enough to handle more than 32 bits.
> > >
> > > Fixes: 554aae35007e ("lib: Add support for generic packing operations")
> > > Signed-off-by: Dan Carpenter <error27@xxxxxxxxx>
> > > ---
> > > lib/packing.c | 5 ++---
> > > 1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/lib/packing.c b/lib/packing.c
> > > index 9a72f4bbf0e2..9d7418052f5a 100644
> > > --- a/lib/packing.c
> > > +++ b/lib/packing.c
> > > @@ -32,12 +32,11 @@ static int get_reverse_lsw32_offset(int offset, size_t len)
> > > static u64 bit_reverse(u64 val, unsigned int width)
> > > {
> > > u64 new_val = 0;
> > > - unsigned int bit;
> > > unsigned int i;
> > >
> > > for (i = 0; i < width; i++) {
> > > - bit = (val & (1 << i)) != 0;
> > > - new_val |= (bit << (width - i - 1));
> > > + if (val & BIT_ULL(1))
> >
> > hmm, why 1 and not i?
>
> Because I'm a moron. Let me resend.
Wait a second, I deliberately wrote the code without conditionals.
Let me look at the code disassembly before and after the patch and see
what they look like.
