Re: [PATCH v7] crypto: scompress: remove memcpy if sg_nents is 1 and pages are lowmem

[Guenter Roeck]

On 3/17/24 16:48, Barry Song wrote:
> On Mon, Mar 18, 2024 at 7:13 AM Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > Hi,
> >
> > On Sat, Mar 02, 2024 at 08:27:45AM +1300, Barry Song wrote:
> > [ ... ]
> > > @@ -152,8 +165,17 @@ static int scomp_acomp_comp_decomp(struct acomp_req *req, int dir)
> > >                        ret = -ENOSPC;
> > >                        goto out;
> > >                }
> > > -             scatterwalk_map_and_copy(scratch->dst, req->dst, 0, req->dlen,
> > > -                                      1);
> > > +             if (dst == scratch->dst) {
> > > +                     scatterwalk_map_and_copy(scratch->dst, req->dst, 0,
> > > +                                              req->dlen, 1);
> > > +             } else {
> > > +                     int nr_pages = DIV_ROUND_UP(req->dst->offset + req->dlen, PAGE_SIZE);
> > > +                     int i;
> > > +                     struct page *dst_page = sg_page(req->dst);
> > > +
> > > +                     for (i = 0; i < nr_pages; i++)
> > > +                             flush_dcache_page(dst_page + i);
> >
> > flush_dcache_page() is an empty macro on some architectures
> > such as xtensa. This results in
>
> Hi Guenter,
>
> this is a bug of xtensa, could you test the patch:

Thanks for the update.

> https://lore.kernel.org/all/20240313045036.51065-1-21cnbao@xxxxxxxxx/

That doesn't build for me.

  CC      arch/xtensa/kernel/asm-offsets.s
In file included from ./include/linux/highmem.h:8,
                 from ./include/linux/bvec.h:10,
                 from ./include/linux/blk_types.h:10,
                 from ./include/linux/writeback.h:13,
                 from ./include/linux/memcontrol.h:23,
                 from ./include/linux/swap.h:9,
                 from ./include/linux/suspend.h:5,
                 from arch/xtensa/kernel/asm-offsets.c:24:
/include/linux/cacheflush.h:9:5: error: "ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE" is not defined, evaluates to 0 [-Werror=undef]
    9 | #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE

A similar works for loongarch, so I don't know what is wrong.
Maybe some context patch is missing.

Guenter