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zlib: Fix big performance regression

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Commit 340fdf1303 ("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.

[trini: Combine assorted patches in to this one, just restoring the
        performance commit]

Fixes: 340fdf1303 ("zlib: Port fix for CVE-2016-9841 to U-Boot")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Christophe Leroy 2024-07-16 08:35:46 -06:00 committed by Tom Rini
parent 4f65851007
commit 4cf1275f2b
2 changed files with 40 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
lib/zlib/inffast.c
View File

@ -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 - 1);
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 */

1
lib/zlib/zlib.h
View File

@ -10,7 +10,6 @@
/* avoid conflicts */
#undef OFF
#undef ASMINF
#undef POSTINC
#undef NO_GZIP
#define GUNZIP
#undef STDC