Source: zlib
Version: 1:1.3.dfsg+really1.3.2-3
Severity: normal
Tags: patch
X-Debbugs-Cc: [email protected]
Dear Maintainer, hi Mark,
zlib 1.3.2 (upstream) ships an s390x CRC-32 implementation (the "crcvx"
optimization, z13+ VGFMA) in contrib/crc32vx/.
In the Debian package it is not built at all, so s390x gets no
hardware-accelerated CRC-32 (~3x slower; see testing below).
Cause
-----
The build glue is present in the tree -- crc32.c, configure and Makefile.in all
reference contrib/crc32vx/ under HAVE_S390X_VX -- but the two source files
(crc32_vx.c, crc32_vx_hooks.h) are missing from the .orig tarball, which keeps
only contrib/minizip out of contrib/.
But contrib/crc32vx is Zlib-licensed and is NOT in debian/copyright
Files-Excluded, so this is an inadvertent repack artifact, I think.
With the files gone the s390x build fails ("No rule to make target
contrib/crc32vx/crc32_vx.c"), which is why -3 added --disable-crcvx.
crcvx is a generically-named switch, but in 1.3.2 its only backend is s390x,
gated behind __s390x__; this has no effect on other architectures.
The current .orig does not seems to be reproducible from the packaging:
running mk-origtargz with the current debian/copyright keeps contrib/crc32vx,
and the .orig additionally lacks amiga/ msdos/ os400/ qnx/ watcom/,
make_vms.com,
zlib.3.pdf, examples/zlib_how.html and more that Files-Excluded does not
mention.
Fix: regenerate the .orig with contrib/crc32vx included
-------------------------------------------------------
The intended fix is to stop dropping contrib/crc32vx from the .orig (no patch).
1. Make debian/copyright Files-Excluded accurate, so a regenerate adds only
contrib/crc32vx and does not re-add the cruft above. Add (but NOT
contrib/crc32vx):
amiga msdos os400 qnx watcom
make_vms.com zlib.3.pdf examples/zlib_how.html
contrib/CMakeLists.txt contrib/README.contrib
contrib/nuget contrib/zlib1-dll contrib/minizip/Makefile
Also document contrib/crc32vx/* (IBM, Zlib) in debian/copyright.
(both changes in the attached debian-copyright.diff)
2. Bump the repack suffix, since the corrected .orig has the same name but a
different checksum and the archive will not accept a changed .orig for the
existing upstream version: e.g. version 1:1.3.dfsg+really1.3.2+dfsg1-1,
orig zlib_1.3.dfsg+really1.3.2+dfsg1.orig.tar.gz. Exact command (packaging
tree, upstream zlib-1.3.2 tarball in the current dir):
mk-origtargz --package zlib --version 1.3.dfsg+really1.3.2+dfsg1 \
--repack --compression gzip --copyright-file debian/copyright \
--directory . zlib-1.3.2.tar.gz
Verify: tar tf zlib_1.3.dfsg+really1.3.2+dfsg1.orig.tar.gz | grep crc32vx
(4 files). Refresh pristine-tar if used.
3. debian/rules: drop --disable-crcvx; add "contrib" to COPYLIST.
(attached debian-rules.diff)
With the files back in the .orig, no (quilt) patch is needed.
Fallback (in case the .orig is not re-rolled)
---------------------------------------------
The attached restore-crc32vx-source.patch re-adds the two files verbatim from
upstream v1.3.2 as a quilt patch; the debian-rules.diff and debian-copyright
attribution still apply. This is a fallback and I think it's not the preferred
route.
Safety
------
No-op off s390x (HAVE_S390X gate). The relevant symbols (s390_crc32_vx,
crc32_z_hook) are local, so there is no exported-ABI/symbols change. The two
historical defects from Ubuntu LP #1982583 (uint32_t signature; define missing
from SFLAGS) are already correct in upstream 1.3.2.
Testing
-------
Native IBM z15 (machine 8561), s390x, VX facility present:
- VX libz (shared and static): correct CRC-32 across sizes 0..5,000,000 x 17
byte-alignments, matching an independent reference and the scalar crc32_z.
- A deliberately-corrupted-VX control build fails from n=79 (VX_MIN_LEN+align),
confirming the vector path is actually executed.
- Shared libz carries s390_crc32_vx + crc32_z_hook (VGFMA instructions
present).
- Real app (python3 zlib, ~300 MB): identical result to scalar, ~2.9x faster.
- amd64: crcvx inert; libz and contrib/minizip build unchanged.
This fixes also Ubuntu LP #1982583 (https://bugs.launchpad.net/bugs/1982583).
Attachments:
- debian-copyright.diff (accurate Files-Excluded for the repack + crc32vx
copyright attribution)
- debian-rules.diff (drop --disable-crcvx; COPYLIST += contrib)
- restore-crc32vx-source.patch (fallback only: re-add the files as a quilt
patch)
Thanks for considering this and BR
Frank
*** /debian-copyright.diff
--- cmp/d3/debian/copyright 2026-03-24 01:05:22.000000000 +0000
+++ /tmp/opencode/copyright.combined 2026-10-02 19:39:40.024072518 +0000
@@ -35,6 +35,19 @@
doc/rfc1951.txt
doc/rfc1952.txt
win32
+ amiga
+ msdos
+ os400
+ qnx
+ watcom
+ make_vms.com
+ zlib.3.pdf
+ examples/zlib_how.html
+ contrib/CMakeLists.txt
+ contrib/README.contrib
+ contrib/nuget
+ contrib/zlib1-dll
+ contrib/minizip/Makefile
Files: *
Copyright: 1995-2013 Jean-loup Gailly and Mark Adler
@@ -50,6 +63,13 @@
2009-2010 Mathias Svensson
License: Zlib
+Files: contrib/crc32vx/*
+Copyright: 2013-2017 IBM Corporation
+ Hendrik Brueckner <[email protected]>
+License: Zlib
+Comment: Originally written for the Linux kernel and relicensed under Zlib
+ by the upstream zlib project.
+
Files: debian/*
Copyright: 2000-2017 Mark Brown
*** debian-rules.diff
--- cmp/d3/debian/rules 2026-04-01 21:50:49.000000000 +0000
+++ zlib-debpr/debian/rules 2026-10-02 15:05:44.419025112 +0000
@@ -70,14 +70,14 @@
CFLAGS+=-DUNALIGNED_OK
endif
-COPYLIST=*.h *.c *.in zlib.map configure zlib.3 test
+COPYLIST=*.h *.c *.in zlib.map configure zlib.3 test contrib
configure-stamp: configure
dh_testdir
if [ ! -f Makefile.stash ]; then cp Makefile Makefile.stash ; fi
- AR=$(AR) CC="$(DEB_HOST_GNU_TYPE)-gcc" CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --shared --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH) --disable-crcvx
+ AR=$(AR) CC="$(DEB_HOST_GNU_TYPE)-gcc" CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --shared --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH)
cd contrib/minizip && autoreconf -fis && CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH) --build=$(DEB_BUILD_GNU_TYPE)
--host=$(DEB_HOST_GNU_TYPE)
*** debian/patches/restore-crc32vx-source.patch
Description: Restore upstream contrib/crc32vx sources stripped by the repack
zlib 1.3.2 adds an s390x CRC-32 implementation using the z/Architecture
Vector Extension (contrib/crc32vx/). The build glue for it is kept in the
Debian tree (crc32.c, configure, Makefile.in all reference it under
HAVE_S390X_VX), but the two source files are dropped by the .orig repack,
which keeps only contrib/minizip out of contrib/. Their absence makes the
s390x build fail ("No rule to make target contrib/crc32vx/crc32_vx.c"), which
is why debian/rules currently passes --disable-crcvx.
.
This patch re-adds the two files verbatim from the upstream 1.3.2 release so
crcvx can be re-enabled. NOTE: the cleaner fix is to stop stripping
contrib/crc32vx in the repack and drop this patch; it is provided for trees
that keep the current .orig. The code is bitreflected CRC-32 using VGFMA,
originally from the Linux kernel (Hendrik Brueckner) and relicensed to zlib.
Origin: upstream, https://github.com/madler/zlib/tree/v1.3.2/contrib/crc32vx
Bug-Ubuntu: https://bugs.launchpad.net/bugs/1982583
Forwarded: not-needed
Last-Update: 2026-10-02
diff --git a/contrib/crc32vx/crc32_vx.c b/contrib/crc32vx/crc32_vx.c
new file mode 100644
index 0000000..e718e34
--- /dev/null
+++ b/contrib/crc32vx/crc32_vx.c
@@ -0,0 +1,254 @@
+/*
+ * Hardware-accelerated CRC-32 variants for Linux on z Systems
+ *
+ * Use the z/Architecture Vector Extension Facility to accelerate the
+ * computing of bitreflected CRC-32 checksums.
+ *
+ * This CRC-32 implementation algorithm is bitreflected and processes
+ * the least-significant bit first (Little-Endian).
+ *
+ * This code was originally written by Hendrik Brueckner
+ * <[email protected]> for use in the Linux kernel and has been
+ * relicensed under the zlib license.
+ */
+#define Z_ONCE
+#include "../../zutil.h"
+#include "crc32_vx_hooks.h"
+
+#include <stdint.h>
+#include <stdio.h>
+#include <vecintrin.h>
+#include <sys/auxv.h>
+
+#ifdef __clang__
+# if ((__clang_major__ == 18) || (__clang_major__ == 19 && (__clang_minor__ <
1 || (__clang_minor__ == 1 && __clang_patchlevel__ < 2))))
+# error crc32_vx optimizations are broken due to compiler bug in Clang
versions: 18.0.0 <= clang_version < 19.1.2. \
+ Either disable the zlib crc32_vx optimization, or switch to another
compiler/compiler version.
+# endif
+#endif
+
+#define VX_MIN_LEN 64
+#define VX_ALIGNMENT 16L
+#define VX_ALIGN_MASK (VX_ALIGNMENT - 1)
+
+typedef unsigned char uv16qi __attribute__((vector_size(16)));
+typedef unsigned int uv4si __attribute__((vector_size(16)));
+typedef unsigned long long uv2di __attribute__((vector_size(16)));
+
+local uint32_t crc32_le_vgfm_16(uint32_t crc, const unsigned char *buf, size_t
len) {
+ /*
+ * The CRC-32 constant block contains reduction constants to fold and
+ * process particular chunks of the input data stream in parallel.
+ *
+ * For the CRC-32 variants, the constants are precomputed according to
+ * these definitions:
+ *
+ * R1 = [(x4*128+32 mod P'(x) << 32)]' << 1
+ * R2 = [(x4*128-32 mod P'(x) << 32)]' << 1
+ * R3 = [(x128+32 mod P'(x) << 32)]' << 1
+ * R4 = [(x128-32 mod P'(x) << 32)]' << 1
+ * R5 = [(x64 mod P'(x) << 32)]' << 1
+ * R6 = [(x32 mod P'(x) << 32)]' << 1
+ *
+ * The bitreflected Barret reduction constant, u', is defined as
+ * the bit reversal of floor(x**64 / P(x)).
+ *
+ * where P(x) is the polynomial in the normal domain and the P'(x) is
the
+ * polynomial in the reversed (bitreflected) domain.
+ *
+ * CRC-32 (IEEE 802.3 Ethernet, ...) polynomials:
+ *
+ * P(x) = 0x04C11DB7
+ * P'(x) = 0xEDB88320
+ */
+ const uv16qi perm_le2be = {15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2,
1, 0}; /* BE->LE mask */
+ const uv2di r2r1 = {0x1C6E41596, 0x154442BD4};
/* R2, R1 */
+ const uv2di r4r3 = {0x0CCAA009E, 0x1751997D0};
/* R4, R3 */
+ const uv2di r5 = {0, 0x163CD6124};
/* R5 */
+ const uv2di ru_poly = {0, 0x1F7011641};
/* u' */
+ const uv2di crc_poly = {0, 0x1DB710641};
/* P'(x) << 1 */
+
+ /*
+ * Load the initial CRC value.
+ *
+ * The CRC value is loaded into the rightmost word of the
+ * vector register and is later XORed with the LSB portion
+ * of the loaded input data.
+ */
+ uv2di v0 = {0, 0};
+ v0 = (uv2di)vec_insert(crc, (uv4si)v0, 3);
+
+ /* Load a 64-byte data chunk and XOR with CRC */
+ uv2di v1 = vec_perm(((uv2di *)buf)[0], ((uv2di *)buf)[0], perm_le2be);
+ uv2di v2 = vec_perm(((uv2di *)buf)[1], ((uv2di *)buf)[1], perm_le2be);
+ uv2di v3 = vec_perm(((uv2di *)buf)[2], ((uv2di *)buf)[2], perm_le2be);
+ uv2di v4 = vec_perm(((uv2di *)buf)[3], ((uv2di *)buf)[3], perm_le2be);
+
+ v1 ^= v0;
+ buf += 64;
+ len -= 64;
+
+ while (len >= 64) {
+ /* Load the next 64-byte data chunk */
+ uv16qi part1 = vec_perm(((uv16qi *)buf)[0], ((uv16qi *)buf)[0],
perm_le2be);
+ uv16qi part2 = vec_perm(((uv16qi *)buf)[1], ((uv16qi *)buf)[1],
perm_le2be);
+ uv16qi part3 = vec_perm(((uv16qi *)buf)[2], ((uv16qi *)buf)[2],
perm_le2be);
+ uv16qi part4 = vec_perm(((uv16qi *)buf)[3], ((uv16qi *)buf)[3],
perm_le2be);
+
+ /*
+ * Perform a GF(2) multiplication of the doublewords in V1 with
+ * the R1 and R2 reduction constants in V0. The intermediate result
+ * is then folded (accumulated) with the next data chunk in PART1 and
+ * stored in V1. Repeat this step for the register contents
+ * in V2, V3, and V4 respectively.
+ */
+ v1 = (uv2di)vec_gfmsum_accum_128(r2r1, v1, part1);
+ v2 = (uv2di)vec_gfmsum_accum_128(r2r1, v2, part2);
+ v3 = (uv2di)vec_gfmsum_accum_128(r2r1, v3, part3);
+ v4 = (uv2di)vec_gfmsum_accum_128(r2r1, v4, part4);
+
+ buf += 64;
+ len -= 64;
+ }
+
+ /*
+ * Fold V1 to V4 into a single 128-bit value in V1. Multiply V1 with R3
+ * and R4 and accumulating the next 128-bit chunk until a single 128-bit
+ * value remains.
+ */
+ v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v2);
+ v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v3);
+ v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v4);
+
+ while (len >= 16) {
+ /* Load next data chunk */
+ v2 = vec_perm(*(uv2di *)buf, *(uv2di *)buf, perm_le2be);
+
+ /* Fold next data chunk */
+ v1 = (uv2di)vec_gfmsum_accum_128(r4r3, v1, (uv16qi)v2);
+
+ buf += 16;
+ len -= 16;
+ }
+
+ /*
+ * Set up a vector register for byte shifts. The shift value must
+ * be loaded in bits 1-4 in byte element 7 of a vector register.
+ * Shift by 8 bytes: 0x40
+ * Shift by 4 bytes: 0x20
+ */
+ uv16qi v9 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+ v9 = vec_insert((unsigned char)0x40, v9, 7);
+
+ /*
+ * Prepare V0 for the next GF(2) multiplication: shift V0 by 8 bytes
+ * to move R4 into the rightmost doubleword and set the leftmost
+ * doubleword to 0x1.
+ */
+ v0 = vec_srb(r4r3, (uv2di)v9);
+ v0[0] = 1;
+
+ /*
+ * Compute GF(2) product of V1 and V0. The rightmost doubleword
+ * of V1 is multiplied with R4. The leftmost doubleword of V1 is
+ * multiplied by 0x1 and is then XORed with rightmost product.
+ * Implicitly, the intermediate leftmost product becomes padded
+ */
+ v1 = (uv2di)vec_gfmsum_128(v0, v1);
+
+ /*
+ * Now do the final 32-bit fold by multiplying the rightmost word
+ * in V1 with R5 and XOR the result with the remaining bits in V1.
+ *
+ * To achieve this by a single VGFMAG, right shift V1 by a word
+ * and store the result in V2 which is then accumulated. Use the
+ * vector unpack instruction to load the rightmost half of the
+ * doubleword into the rightmost doubleword element of V1; the other
+ * half is loaded in the leftmost doubleword.
+ * The vector register with CONST_R5 contains the R5 constant in the
+ * rightmost doubleword and the leftmost doubleword is zero to ignore
+ * the leftmost product of V1.
+ */
+ v9 = vec_insert((unsigned char)0x20, v9, 7);
+ v2 = vec_srb(v1, (uv2di)v9);
+ v1 = vec_unpackl((uv4si)v1); /* Split rightmost doubleword */
+ v1 = (uv2di)vec_gfmsum_accum_128(r5, v1, (uv16qi)v2);
+
+ /*
+ * Apply a Barret reduction to compute the final 32-bit CRC value.
+ *
+ * The input values to the Barret reduction are the degree-63 polynomial
+ * in V1 (R(x)), degree-32 generator polynomial, and the reduction
+ * constant u. The Barret reduction result is the CRC value of R(x) mod
+ * P(x).
+ *
+ * The Barret reduction algorithm is defined as:
+ *
+ * 1. T1(x) = floor( R(x) / x^32 ) GF2MUL u
+ * 2. T2(x) = floor( T1(x) / x^32 ) GF2MUL P(x)
+ * 3. C(x) = R(x) XOR T2(x) mod x^32
+ *
+ * Note: The leftmost doubleword of vector register containing
+ * CONST_RU_POLY is zero and, thus, the intermediate GF(2) product
+ * is zero and does not contribute to the final result.
+ */
+
+ /* T1(x) = floor( R(x) / x^32 ) GF2MUL u */
+ v2 = vec_unpackl((uv4si)v1);
+ v2 = (uv2di)vec_gfmsum_128(ru_poly, v2);
+
+ /*
+ * Compute the GF(2) product of the CRC polynomial with T1(x) in
+ * V2 and XOR the intermediate result, T2(x), with the value in V1.
+ * The final result is stored in word element 2 of V2.
+ */
+ v2 = vec_unpackl((uv4si)v2);
+ v2 = (uv2di)vec_gfmsum_accum_128(crc_poly, v2, (uv16qi)v1);
+
+ return ((uv4si)v2)[2];
+}
+
+
+local unsigned long s390_crc32_vx(unsigned long crc, const unsigned char FAR
*buf, z_size_t len)
+{
+ uintptr_t prealign, aligned, remaining;
+
+ if (buf == Z_NULL) return 0UL;
+
+ if (len < VX_MIN_LEN + VX_ALIGN_MASK)
+ return crc32_z(crc, buf, len);
+
+ if ((uintptr_t)buf & VX_ALIGN_MASK) {
+ prealign = VX_ALIGNMENT - ((uintptr_t)buf & VX_ALIGN_MASK);
+ len -= prealign;
+ crc = crc32_z(crc, buf, prealign);
+ buf += prealign;
+ }
+ aligned = len & ~VX_ALIGN_MASK;
+ remaining = len & VX_ALIGN_MASK;
+
+ crc = crc32_le_vgfm_16(crc ^ 0xffffffff, buf, (size_t)aligned) ^
0xffffffff;
+
+ if (remaining)
+ crc = crc32_z(crc, buf + aligned, remaining);
+
+ return crc;
+}
+
+local z_once_t s390_crc32_made = Z_ONCE_INIT;
+local void s390_crc32_setup() {
+ unsigned long hwcap = getauxval(AT_HWCAP);
+
+ if (hwcap & HWCAP_S390_VX)
+ crc32_z_hook = s390_crc32_vx;
+ else
+ crc32_z_hook = crc32_z;
+}
+
+local unsigned long s390_crc32_init(unsigned long crc, const unsigned char FAR
*buf, z_size_t len)
+{
+ z_once(&s390_crc32_made,s390_crc32_setup);
+ return crc32_z_hook(crc, buf, len);
+}
+
+ZLIB_INTERNAL unsigned long (*crc32_z_hook)(unsigned long crc, const unsigned
char FAR *buf, z_size_t len) = s390_crc32_init;
diff --git a/contrib/crc32vx/crc32_vx_hooks.h
b/contrib/crc32vx/crc32_vx_hooks.h
new file mode 100644
index 0000000..951c318
--- /dev/null
+++ b/contrib/crc32vx/crc32_vx_hooks.h
@@ -0,0 +1,9 @@
+#ifndef CRC32_VX_HOOKS_H
+#define CRC32_VX_HOOKS_H
+
+/**
+ * CRC HOOKS
+ */
+ZLIB_INTERNAL extern unsigned long (*crc32_z_hook)(unsigned long crc, const
unsigned char FAR *buf, z_size_t len);
+
--- cmp/d3/debian/copyright 2026-03-24 01:05:22.000000000 +0000
+++ /tmp/opencode/copyright.combined 2026-10-02 19:39:40.024072518 +0000
@@ -35,6 +35,19 @@
doc/rfc1951.txt
doc/rfc1952.txt
win32
+ amiga
+ msdos
+ os400
+ qnx
+ watcom
+ make_vms.com
+ zlib.3.pdf
+ examples/zlib_how.html
+ contrib/CMakeLists.txt
+ contrib/README.contrib
+ contrib/nuget
+ contrib/zlib1-dll
+ contrib/minizip/Makefile
Files: *
Copyright: 1995-2013 Jean-loup Gailly and Mark Adler
@@ -50,6 +63,13 @@
2009-2010 Mathias Svensson
License: Zlib
+Files: contrib/crc32vx/*
+Copyright: 2013-2017 IBM Corporation
+ Hendrik Brueckner <[email protected]>
+License: Zlib
+Comment: Originally written for the Linux kernel and relicensed under Zlib
+ by the upstream zlib project.
+
Files: debian/*
Copyright: 2000-2017 Mark Brown
License: Zlib
--- cmp/d3/debian/rules 2026-04-01 21:50:49.000000000 +0000
+++ zlib-debpr/debian/rules 2026-10-02 15:05:44.419025112 +0000
@@ -70,14 +70,14 @@
CFLAGS+=-DUNALIGNED_OK
endif
-COPYLIST=*.h *.c *.in zlib.map configure zlib.3 test
+COPYLIST=*.h *.c *.in zlib.map configure zlib.3 test contrib
configure-stamp: configure
dh_testdir
if [ ! -f Makefile.stash ]; then cp Makefile Makefile.stash ; fi
- AR=$(AR) CC="$(DEB_HOST_GNU_TYPE)-gcc" CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --shared --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH) --disable-crcvx
+ AR=$(AR) CC="$(DEB_HOST_GNU_TYPE)-gcc" CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --shared --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH)
cd contrib/minizip && autoreconf -fis && CFLAGS="$(CFLAGS)"
LDFLAGS="$(LDFLAGS)" uname=GNU ./configure --prefix=/usr
--libdir=\$${prefix}/lib/$(DEB_HOST_MULTIARCH) --build=$(DEB_BUILD_GNU_TYPE)
--host=$(DEB_HOST_GNU_TYPE)
