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 > > diff --git a/lib/zlib/inffast.c b/lib/zlib/inffast.c > index 5e2a65ad4d..c4b1d12258 100644 > --- a/lib/zlib/inffast.c > +++ b/lib/zlib/inffast.c > @@ -236,18 +236,47 @@ unsigned start; /* inflate()'s starting value > for strm->avail_out */ > } > } > else { > + unsigned short *sout; > + unsigned long loops; > + > from = out - dist; /* copy direct from output */ > - do { /* minimum length is three */ > - *out++ = *from++; > - *out++ = *from++; > - *out++ = *from++; > - len -= 3; > - } while (len > 2); > - if (len) { > - *out++ = *from++; > - if (len > 1) > - *out++ = *from++; > - } > + /* minimum length is three */ > + /* Align out addr */ > + if (!((long)(out - 1) & 1)) { > + *out++ = *from++; > + len--; > + } > + sout = (unsigned short *)out; > + if (dist > 2 ) { > + unsigned short *sfrom; > + > + sfrom = (unsigned short *)from; > + loops = len >> 1; > + do > + *sout++ = get_unaligned(++sfrom); > + while (--loops); > + out = (unsigned char *)sout; > + from = (unsigned char *)sfrom; > + } else { /* dist == 1 or dist == 2 */ > + unsigned short pat16; > + > + pat16 = *(sout-2); > + if (dist == 1) > +#if defined(__BIG_ENDIAN) > + pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8); > +#elif defined(__LITTLE_ENDIAN) > + pat16 = (pat16 & 0xff00) | ((pat16 & 0xff00 ) >> 8); > +#else > +#error __BIG_ENDIAN nor __LITTLE_ENDIAN is defined > +#endif > + loops = len >> 1; > + do > + *sout++ = pat16; > + while (--loops); > + out = (unsigned char *)sout; > + } > + if (len & 1) > + *out++ = *from++; > } > } > else if ((op & 64) == 0) { /* 2nd level distance code */ > -- > 2.44.0 > -- Tom
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