[PATCH] zlib: Fix big performance regression
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.leroy@csgroup.eu --- lib/zlib/inffast.c | 51 ++++++++++++++++++++++++++++++++++++---------- 1 file changed, 40 insertions(+), 11 deletions(-)
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 */
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.leroy@csgroup.eu
Good work.
Reviewed-by: Tom Rini trini@konsulko.com
And can you please head over to https://github.com/madler/zlib and file an issue, or pull request with your changes explaining why? I would hope they're interested in performance regressions on slower parts still. Thanks!
On Thu, 2024-06-27 at 10:25 +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.leroy@csgroup.eu
Thanks for looking after my old optimization :)
Jocke
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.leroy@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
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.leroy@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.
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.leroy@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;
Christophe
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.leroy@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.
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.leroy@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.
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.leroy@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);
Christophe
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.leroy@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;
pat16 = *(sout-2+2*OFF);
pat16 = *(sout-1+OFF); if (dist == 1)#if defined(__BIG_ENDIAN) pat16 = (pat16 & 0xff) | ((pat16 & 0xff ) << 8);
OK, so at this point we're changing a lot of common paths, to things that haven't been tested before. I suspect it's all fine, but for the release on July 1 I'm going to revert the zlib update, and then we can perform these corrections and re-introduce the optimization after release, when they'll get the most amount of testing.
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.leroy@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;
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!
Le 05/07/2024 à 17:47, Tom Rini a écrit :
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.leroy@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;
pat16 = *(sout-2+2*OFF);
pat16 = *(sout-1+OFF); if (dist == 1)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!
I will try to send something tomorrow.
participants (3)
-
Christophe Leroy -
Joakim Tjernlund -
Tom Rini