linux-kernel - Re: [PATCH v2 59/62] livepatch/klp-build: Introduce klp-build script for generating livepatch modules

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Message-ID: <sfzy2ojfzsjya24pbxw7fb77ua6smjixqjk7qrbt2i3q7wh25b@3kzz22tairgr>
Date: Tue, 10 Jun 2025 09:10:19 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: Joe Lawrence <joe.lawrence@...hat.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, 
	Petr Mladek <pmladek@...e.com>, Miroslav Benes <mbenes@...e.cz>, live-patching@...r.kernel.org, 
	Song Liu <song@...nel.org>, laokz <laokz@...mail.com>, Jiri Kosina <jikos@...nel.org>, 
	Marcos Paulo de Souza <mpdesouza@...e.com>, Weinan Liu <wnliu@...gle.com>, 
	Fazla Mehrab <a.mehrab@...edance.com>, Chen Zhongjin <chenzhongjin@...wei.com>, 
	Puranjay Mohan <puranjay@...nel.org>
Subject: Re: [PATCH v2 59/62] livepatch/klp-build: Introduce klp-build script
 for generating livepatch modules

On Mon, Jun 09, 2025 at 10:34:43PM -0400, Joe Lawrence wrote:
> On Fri, May 09, 2025 at 01:17:23PM -0700, Josh Poimboeuf wrote:
> > +revert_patch() {
> > +	local patch="$1"
> > +	shift
> > +	local extra_args=("$@")
> > +	local tmp=()
> > +
> > +	( cd "$SRC" && git apply --reverse "${extra_args[@]}" "$patch" )
> > +	git_refresh "$patch"
> > +
> > +	for p in "${APPLIED_PATCHES[@]}"; do
> > +		[[ "$p" == "$patch" ]] && continue
> > +		tmp+=("$p")
> > +	done
> > +
> > +	APPLIED_PATCHES=("${tmp[@]}")
> > +}
> 
> You may consider a slight adjustment to revert_patch() to handle git
> format-patch generated .patches?  The reversal trips up on the git
> version trailer:
> 
>   warning: recount: unexpected line: 2.47.1

Thanks.  Looks like the normal apply with --recount also trips it up.  I
have the below:

diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index f689a4d143c6..1ff5e66f4c53 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -337,7 +337,14 @@ apply_patch() {
 
 	[[ ! -f "$patch" ]] && die "$patch doesn't exist"
 
-	( cd "$SRC" && git apply "${extra_args[@]}" "$patch" )
+	(
+		cd "$SRC"
+
+		# The sed removes the version signature from 'git format-patch',
+		# otherwise 'git apply --recount' warns.
+		sed -n '/^-- /q;p' "$patch" |
+			git apply "${extra_args[@]}"
+	)
 
 	APPLIED_PATCHES+=("$patch")
 }
@@ -348,7 +355,12 @@ revert_patch() {
 	local extra_args=("$@")
 	local tmp=()
 
-	( cd "$SRC" && git apply --reverse "${extra_args[@]}" "$patch" )
+	(
+		cd "$SRC"
+
+		sed -n '/^-- /q;p' "$patch" |
+			git apply --reverse "${extra_args[@]}"
+	)
 	git_refresh "$patch"
 
 	for p in "${APPLIED_PATCHES[@]}"; do