kbuild: add variables for compression tools

Allow user to use alternative implementations of compression tools,
such as pigz, pbzip2, pxz. For example, multi-threaded tools to
speed up the build:
$ make GZIP=pigz BZIP2=pbzip2

Variables _GZIP, _BZIP2, _LZOP are used internally because original env
vars are reserved by the tools. The use of GZIP in gzip tool is obsolete
since 2015. However, alternative implementations (e.g., pigz) still rely
on it. BZIP2, BZIP, LZOP vars are not obsolescent.

The credit goes to @grsecurity.

As a sidenote, for multi-threaded lzma, xz compression one can use:
$ export XZ_OPT="--threads=0"

Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

10 files changed, 45 insertions, 24 deletions

diff --git a/Makefile b/Makefile
index 7b750dc0b2da..64ebbc1dfbef 100644
--- a/Makefile
+++ b/Makefile
@@ -458,6 +458,26 @@ PYTHON		= python
 PYTHON3		= python3
 CHECK		= sparse
 BASH		= bash
+GZIP		= gzip
+BZIP2		= bzip2
+LZOP		= lzop
+LZMA		= lzma
+LZ4		= lz4c
+XZ		= xz
+
+# GZIP, BZIP2, LZOP env vars are used by the tools. Support them as the command
+# line interface, but use _GZIP, _BZIP2, _LZOP internally.
+_GZIP          := $(GZIP)
+_BZIP2         := $(BZIP2)
+_LZOP          := $(LZOP)
+
+# Reset GZIP, BZIP2, LZOP in this Makefile
+override GZIP=
+override BZIP2=
+override LZOP=
+
+# Reset GZIP, BZIP2, LZOP in recursive invocations
+MAKEOVERRIDES += GZIP= BZIP2= LZOP=
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
 		  -Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
@@ -506,6 +526,7 @@ CLANG_FLAGS :=
 export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
 export CPP AR NM STRIP OBJCOPY OBJDUMP OBJSIZE READELF PAHOLE LEX YACC AWK INSTALLKERNEL
 export PERL PYTHON PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
+export _GZIP _BZIP2 _LZOP LZMA LZ4 XZ
 export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
@@ -1020,10 +1041,10 @@ export mod_strip_cmd
 mod_compress_cmd = true
 ifdef CONFIG_MODULE_COMPRESS
   ifdef CONFIG_MODULE_COMPRESS_GZIP
-    mod_compress_cmd = gzip -n -f
+    mod_compress_cmd = $(_GZIP) -n -f
   endif # CONFIG_MODULE_COMPRESS_GZIP
   ifdef CONFIG_MODULE_COMPRESS_XZ
-    mod_compress_cmd = xz -f
+    mod_compress_cmd = $(XZ) -f
   endif # CONFIG_MODULE_COMPRESS_XZ
 endif # CONFIG_MODULE_COMPRESS
 export mod_compress_cmd
diff --git a/arch/arm/boot/deflate_xip_data.sh b/arch/arm/boot/deflate_xip_data.sh
index 40937248cebe..739f0464321e 100755
--- a/arch/arm/boot/deflate_xip_data.sh
+++ b/arch/arm/boot/deflate_xip_data.sh
@@ -56,7 +56,7 @@ trap 'rm -f "$XIPIMAGE.tmp"; exit 1' 1 2 3
 # substitute the data section by a compressed version
 $DD if="$XIPIMAGE" count=$data_start iflag=count_bytes of="$XIPIMAGE.tmp"
 $DD if="$XIPIMAGE"  skip=$data_start iflag=skip_bytes |
-gzip -9 >> "$XIPIMAGE.tmp"
+$_GZIP -9 >> "$XIPIMAGE.tmp"
 
 # replace kernel binary
 mv -f "$XIPIMAGE.tmp" "$XIPIMAGE"
diff --git a/arch/ia64/Makefile b/arch/ia64/Makefile
index 32240000dc0c..f817f3d5e758 100644
--- a/arch/ia64/Makefile
+++ b/arch/ia64/Makefile
@@ -40,7 +40,7 @@ $(error Sorry, you need a newer version of the assember, one that is built from
 endif
 
 quiet_cmd_gzip = GZIP    $@
-cmd_gzip = cat $(real-prereqs) | gzip -n -f -9 > $@
+cmd_gzip = cat $(real-prereqs) | $(_GZIP) -n -f -9 > $@
 
 quiet_cmd_objcopy = OBJCOPY $@
 cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
diff --git a/arch/m68k/Makefile b/arch/m68k/Makefile
index 5d9288384096..ce6db5e5a5a3 100644
--- a/arch/m68k/Makefile
+++ b/arch/m68k/Makefile
@@ -135,10 +135,10 @@ vmlinux.gz: vmlinux
 ifndef CONFIG_KGDB
 	cp vmlinux vmlinux.tmp
 	$(STRIP) vmlinux.tmp
-	gzip -9c vmlinux.tmp >vmlinux.gz
+	$(_GZIP) -9c vmlinux.tmp >vmlinux.gz
 	rm vmlinux.tmp
 else
-	gzip -9c vmlinux >vmlinux.gz
+	$(_GZIP) -9c vmlinux >vmlinux.gz
 endif
 
 bzImage: vmlinux.bz2
@@ -148,10 +148,10 @@ vmlinux.bz2: vmlinux
 ifndef CONFIG_KGDB
 	cp vmlinux vmlinux.tmp
 	$(STRIP) vmlinux.tmp
-	bzip2 -1c vmlinux.tmp >vmlinux.bz2
+	$(_BZIP2) -1c vmlinux.tmp >vmlinux.bz2
 	rm vmlinux.tmp
 else
-	bzip2 -1c vmlinux >vmlinux.bz2
+	$(_BZIP2) -1c vmlinux >vmlinux.bz2
 endif
 
 archclean:
diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile
index 628cd8bb7ad8..e1aa514aeb36 100644
--- a/arch/parisc/Makefile
+++ b/arch/parisc/Makefile
@@ -162,7 +162,7 @@ vmlinuz: bzImage
 	$(OBJCOPY) $(boot)/bzImage $@
 else
 vmlinuz: vmlinux
-	@gzip -cf -9 $< > $@
+	@$(_GZIP) -cf -9 $< > $@
 endif
 
 install:
diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh
index e13ca842eb7e..c1510f0ab3ea 100755
--- a/kernel/gen_kheaders.sh
+++ b/kernel/gen_kheaders.sh
@@ -88,7 +88,7 @@ find $cpio_dir -type f -print0 |
 find $cpio_dir -printf "./%P\n" | LC_ALL=C sort | \
     tar "${KBUILD_BUILD_TIMESTAMP:+--mtime=$KBUILD_BUILD_TIMESTAMP}" \
     --owner=0 --group=0 --numeric-owner --no-recursion \
-    -Jcf $tarfile -C $cpio_dir/ -T - > /dev/null
+    -I $XZ -cf $tarfile -C $cpio_dir/ -T - > /dev/null
 
 echo $headers_md5 > kernel/kheaders.md5
 echo "$this_file_md5" >> kernel/kheaders.md5
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index e598b07e6de4..127f2a7e3ced 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -244,7 +244,7 @@ cmd_objcopy = $(OBJCOPY) $(OBJCOPYFLAGS) $(OBJCOPYFLAGS_$(@F)) $< $@
 # ---------------------------------------------------------------------------
 
 quiet_cmd_gzip = GZIP    $@
-      cmd_gzip = cat $(real-prereqs) | gzip -n -f -9 > $@
+      cmd_gzip = cat $(real-prereqs) | $(_GZIP) -n -f -9 > $@
 
 # DTC
 # ---------------------------------------------------------------------------
@@ -337,19 +337,19 @@ printf "%08x\n" $$dec_size |						\
 )
 
 quiet_cmd_bzip2 = BZIP2   $@
-      cmd_bzip2 = { cat $(real-prereqs) | bzip2 -9; $(size_append); } > $@
+      cmd_bzip2 = { cat $(real-prereqs) | $(_BZIP2) -9; $(size_append); } > $@
 
 # Lzma
 # ---------------------------------------------------------------------------
 
 quiet_cmd_lzma = LZMA    $@
-      cmd_lzma = { cat $(real-prereqs) | lzma -9; $(size_append); } > $@
+      cmd_lzma = { cat $(real-prereqs) | $(LZMA) -9; $(size_append); } > $@
 
 quiet_cmd_lzo = LZO     $@
-      cmd_lzo = { cat $(real-prereqs) | lzop -9; $(size_append); } > $@
+      cmd_lzo = { cat $(real-prereqs) | $(_LZOP) -9; $(size_append); } > $@
 
 quiet_cmd_lz4 = LZ4     $@
-      cmd_lz4 = { cat $(real-prereqs) | lz4c -l -c1 stdin stdout; \
+      cmd_lz4 = { cat $(real-prereqs) | $(LZ4) -l -c1 stdin stdout; \
                   $(size_append); } > $@
 
 # U-Boot mkimage
@@ -396,7 +396,7 @@ quiet_cmd_xzkern = XZKERN  $@
                      $(size_append); } > $@
 
 quiet_cmd_xzmisc = XZMISC  $@
-      cmd_xzmisc = cat $(real-prereqs) | xz --check=crc32 --lzma2=dict=1MiB > $@
+      cmd_xzmisc = cat $(real-prereqs) | $(XZ) --check=crc32 --lzma2=dict=1MiB > $@
 
 # ASM offsets
 # ---------------------------------------------------------------------------
diff --git a/scripts/Makefile.package b/scripts/Makefile.package
index 02135d2671a6..b2b6153af63a 100644
--- a/scripts/Makefile.package
+++ b/scripts/Makefile.package
@@ -45,7 +45,7 @@ if test "$(objtree)" != "$(srctree)"; then \
 	false; \
 fi ; \
 $(srctree)/scripts/setlocalversion --save-scmversion; \
-tar -cz $(RCS_TAR_IGNORE) -f $(2).tar.gz \
+tar -I $(_GZIP) -c $(RCS_TAR_IGNORE) -f $(2).tar.gz \
 	--transform 's:^:$(2)/:S' $(TAR_CONTENT) $(3); \
 rm -f $(objtree)/.scmversion
 
@@ -127,9 +127,9 @@ util/PERF-VERSION-GEN $(CURDIR)/$(perf-tar)/);              \
 tar rf $(perf-tar).tar $(perf-tar)/HEAD $(perf-tar)/PERF-VERSION-FILE; \
 rm -r $(perf-tar);                                                  \
 $(if $(findstring tar-src,$@),,                                     \
-$(if $(findstring bz2,$@),bzip2,                                    \
-$(if $(findstring gz,$@),gzip,                                      \
-$(if $(findstring xz,$@),xz,                                        \
+$(if $(findstring bz2,$@),$(_BZIP2),                                 \
+$(if $(findstring gz,$@),$(_GZIP),                                  \
+$(if $(findstring xz,$@),$(XZ),                                     \
 $(error unknown target $@))))                                       \
 	-f -9 $(perf-tar).tar)
 
diff --git a/scripts/package/buildtar b/scripts/package/buildtar
index 77c7caefede1..ad62c6879622 100755
--- a/scripts/package/buildtar
+++ b/scripts/package/buildtar
@@ -28,15 +28,15 @@ case "${1}" in
 		opts=
 		;;
 	targz-pkg)
-		opts=--gzip
+		opts="-I ${_GZIP}"
 		tarball=${tarball}.gz
 		;;
 	tarbz2-pkg)
-		opts=--bzip2
+		opts="-I ${_BZIP2}"
 		tarball=${tarball}.bz2
 		;;
 	tarxz-pkg)
-		opts=--xz
+		opts="-I ${XZ}"
 		tarball=${tarball}.xz
 		;;
 	*)
diff --git a/scripts/xz_wrap.sh b/scripts/xz_wrap.sh
index 7a2d372f4885..76e9cbcfbeab 100755
--- a/scripts/xz_wrap.sh
+++ b/scripts/xz_wrap.sh
@@ -20,4 +20,4 @@ case $SRCARCH in
 	sparc)          BCJ=--sparc ;;
 esac
 
-exec xz --check=crc32 $BCJ --lzma2=$LZMA2OPTS,dict=32MiB
+exec $XZ --check=crc32 $BCJ --lzma2=$LZMA2OPTS,dict=32MiB