On Sun, Jun 30, 2024 at 08:49:08PM +0200, Christophe Leroy wrote:
>
>
> Le 30/06/2024 à 20:28, Christophe Leroy a écrit :
> >
> >
> > Le 30/06/2024 à 16:54, Tom Rini a écrit :
> > > On Sun, Jun 30, 2024 at 10:47:06AM +0200, Christophe Leroy wrote:
> > > >
> > > >
> > > > Le 27/06/2024 à 21:40, Tom Rini a écrit :
> > > > > On Thu, Jun 27, 2024 at 01:34:55PM -0600, Tom Rini wrote:
> > > > > > On Thu, Jun 27, 2024 at 10:25:21AM +0200, Christophe Leroy wrote:
> > > > > >
> > > > > > > Commit 340fdf1303dc ("zlib: Port fix for CVE-2016-9841 to U-Boot")
> > > > > > > brings a big performance regression in inflate_fast(), which leads
> > > > > > > to watchdog timer reset on powerpc 8xx.
> > > > > > >
> > > > > > > It looks like that commit does more than what it describe, it
> > > > > > > especially removed an important optimisation that was doing copies
> > > > > > > using halfwords instead of bytes. That unexpected change
> > > > > > > multiplied
> > > > > > > by almost 4 the time spent in inflate_fast() and increased by 40%
> > > > > > > the overall time needed to uncompress linux kernel image.
> > > > > > >
> > > > > > > So partially revert that commit but keep post incrementation as it
> > > > > > > is the initial purpose of said commit.
> > > > > > >
> > > > > > > Fixes: 340fdf1303dc ("zlib: Port fix for CVE-2016-9841 to U-Boot")
> > > > > > > Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> > > > > > > ---
> > > > > > > lib/zlib/inffast.c | 51
> > > > > > > ++++++++++++++++++++++++++++++++++++----------
> > > > > > > 1 file changed, 40 insertions(+), 11 deletions(-)
> > > > > >
> > > > > > Both this, and my mostly revert lead to CI failures around
> > > > > > compression
> > > > > > tests:
> > > > > > https://source.denx.de/u-boot/u-boot/-/jobs/859329
> > > > >
> > > > > A full revert however, is fine.
> > > > >
> > > >
> > > > Is it that ? :
> > > >
> > > > FAILED
> > > > test/py/tests/test_ut.py::test_ut[ut_compression_compression_test_gzip]
> > > >
> > > > It seems like when the optimisation was added by commit
> > > > cd514aeb996e ("zlib:
> > > > Optimize decompression"), only the pre-increment implementation was
> > > > available.
> > > >
> > > > When POSTINC was added by commit e89516f031db ("zlib: split up to match
> > > > original source tree"), I guess it was not verified because POSTINC is
> > > > #undef by zlib.h.
> > > >
> > > > With the following change I don't get the FAILED
> > > > ut_compression_compression_test_gzip CI anymore
> > > > (https://source.denx.de/u-boot/custodians/u-boot-mpc8xx/-/jobs/859937)
> > > >
> > > > diff --git a/lib/zlib/inffast.c b/lib/zlib/inffast.c
> > > > index c271d85ea1..5dc0574202 100644
> > > > --- a/lib/zlib/inffast.c
> > > > +++ b/lib/zlib/inffast.c
> > > > @@ -257,7 +257,7 @@ void inflate_fast(z_streamp strm, unsigned start)
> > > > sfrom = (unsigned short *)(from - OFF);
> > > > loops = len >> 1;
> > > > do
> > > > - PUP(sout) = get_unaligned(++sfrom);
> > > > + PUP(sout) = get_unaligned(sfrom++);
> > > > while (--loops);
> > > > out = (unsigned char *)sout + OFF;
> > > > from = (unsigned char *)sfrom + OFF;
> > >
> > > Ah, thanks! Testing again now.
> > >
> >
> > That's probably not enough. I thought other failures were unrelated but
> > I gave it a try with a full revert and I get no failure at all with that
> > so there must be other things.
> >
> > I find that pat16 = *(sout-2+2*OFF) suspicious, sout being a short it
> > means -4 bytes which is not what is expected I think.
>
> That's it. I get all green with the following, see
> https://source.denx.de/u-boot/custodians/u-boot-mpc8xx/-/pipelines/21391
>
> diff --git a/lib/zlib/inffast.c b/lib/zlib/inffast.c
> index c271d85ea1..69268caee8 100644
> --- a/lib/zlib/inffast.c
> +++ b/lib/zlib/inffast.c
> @@ -257,14 +257,14 @@ void inflate_fast(z_streamp strm, unsigned start)
> sfrom = (unsigned short *)(from - OFF);
> loops = len >> 1;
> do
> - PUP(sout) = get_unaligned(++sfrom);
> + PUP(sout) = get_unaligned(sfrom++);
> while (--loops);
> out = (unsigned char *)sout + OFF;
> from = (unsigned char *)sfrom + OFF;
> } else { /* dist == 1 or dist == 2 */
> unsigned short pat16;
>
> - pat16 = *(sout-2+2*OFF);
> + pat16 = *(sout-1+OFF);
> if (dist == 1)
> #if defined(__BIG_ENDIAN)
> pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);Now that the release is out, can you please do a new patch to re-introduce the optimization required on your platform? A revert of "bbacdd3ef7762fbdeab43ceea5205d1fd0f25bbd" is required first (and separate) and I'll push that shortly. If you don't have time currently, I can try and v2 your original patch with these changes included, thanks! -- Tom
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