From f38c64b7e490c6de1208f277d767bd7b8029edcc Mon Sep 17 00:00:00 2001

From: Josh Poimboeuf <jpoimboe@redhat.com>

Date: Mon, 13 Mar 2023 13:51:01 -0700

Subject: [PATCH 108/112] kpatch-build: Fix setlocalversion issue with 6.3

 kernel

The kernel has a VERMAGIC_STRING, e.g. "6.2.0".  The module loader uses

that string to ensure that all loaded modules' version strings match the

kernel's.

If the kernel source is in a git tree, and if there are uncommitted

changes, the version string will have a '+' or "-dirty" appended to it,

like "6.1.0+" or "6.2.0-dirty".  This dirty tree detection is done by

the setlocalversion script.

This affects kpatch-build in a few ways.  When it builds the original

kernel, in some cases there are uncommitted changes to the makefiles.

When it builds the patched kernel, there are additional uncommitted

changes due to the .patch file being applied.

We want to avoid the VERMAGIC_STRING changing between builds.  Otherwise

it would cause problems:

  - object code which uses that string would change unnecessarily,

    causing a false positive change detected by create-diff-object

  - the linked patch module would report the wrong version, resulting in

    the module failing to load due to version mismatch.

Up until now, the version was prevented from changing by running

`setlocalversion --save-scmversion` before the build.  That command

hard-codes the version by saving it to a file which is then

automatically read later during future invocations of the kernel build.

Unfortunately that feature was removed in the 6.3 merge window with

commit f6e09b07cc12 ("kbuild: do not put .scmversion into the source

tarball").  So we need to come up with a new approach.

Fix it by temporarily replacing the setlocalversion script with a

one-liner which just echo's the original version.  I think this is

unfortunately the best we can do, as we really can't handle

VERMAGIC_STRING changing, either during/between kernel builds or during

the module link.

Fixes #1335.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

(cherry picked from commit 629b5acf3dab0311e1bebbffec4908999273d58d)

---

 kpatch-build/kpatch-build | 25 +++++++++++++++++++++----

 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/kpatch-build/kpatch-build b/kpatch-build/kpatch-build

index 938e88f..429f214 100755

--- a/kpatch-build/kpatch-build

+++ b/kpatch-build/kpatch-build

@@ -166,11 +166,9 @@ remove_patches() {

 }

 cleanup() {

-	rm -f "$BUILDDIR/.scmversion"

-

 	remove_patches

-	# restore original vmlinux if it was overwritten by sourcedir build

+	# restore any files that were modified for the build

 	[[ -e "$TEMPDIR/vmlinux" ]] && mv -f "$TEMPDIR/vmlinux" "$KERNEL_SRCDIR/"

 	# restore any files that were modified for the build

@@ -178,6 +176,7 @@ cleanup() {

 	[[ -e "$TEMPDIR/Makefile.modfinal" ]] && mv -f "$TEMPDIR/Makefile.modfinal" "$KERNEL_SRCDIR/scripts"

 	[[ -e "$TEMPDIR/Makefile.build" ]] && mv -f "$TEMPDIR/Makefile.build" "$KERNEL_SRCDIR/scripts"

 	[[ -e "$TEMPDIR/Makefile" ]] && mv -f "$TEMPDIR/Makefile" "$KERNEL_SRCDIR"

+	[[ -e "$TEMPDIR/setlocalversion" ]] && mv -f "$TEMPDIR/setlocalversion" "$KERNEL_SRCDIR/scripts"

 	[[ "$DEBUG" -eq 0 ]] && rm -rf "$TEMPDIR"

 	rm -rf "$RPMTOPDIR"

@@ -994,6 +993,25 @@ if [[ -z "$OOT_MODULE" && ! "$CONFIGFILE" -ef "$KERNEL_SRCDIR"/.config ]] ; then

 	cp -f "$CONFIGFILE" "$KERNEL_SRCDIR/.config" || die

 fi

+# When the kernel source is in a git repo, applying the patch (plus the

+# Makefile sed hacks we do) can cause it to be built with "+" or "dirty"

+# appended to the kernel version string (VERMAGIC_STRING), even if the original

+# kernel was not dirty.  That can complicate both the build (create-diff-object

+# false positive changes) and the patch module link (module version mismatch

+# load failures).

+#

+# Prevent that by replacing the original setlocalversion with a friendlier one

+# which just echo's the original version.  This should be done before any

+# changes to the source.

+if [[ -n "$USERSRCDIR" && -e "$KERNEL_SRCDIR/.git" ]]; then

+	cd "$KERNEL_SRCDIR" || die

+	cp -f scripts/setlocalversion "$TEMPDIR" || die

+	LOCALVERSION="$(make kernelversion)"

+	LOCALVERSION="$(KERNELVERSION="$LOCALVERSION" ./scripts/setlocalversion)"

+	[[ -n "$LOCALVERSION" ]] || die "setlocalversion failed"

+	echo "echo $LOCALVERSION" > scripts/setlocalversion

+fi

+

 # kernel option checking

 trace_off "reading .config"

@@ -1131,7 +1149,6 @@ fi

 save_env

 echo "Building original source"

-[[ -n "$OOT_MODULE" ]] || ./scripts/setlocalversion --save-scmversion || die

 unset KPATCH_GCC_TEMPDIR

 KPATCH_CC_PREFIX="$TOOLSDIR/kpatch-cc "

-- 

2.45.1