linux-kernel - [tip: objtool/urgent] livepatch/klp-build: Fix klp-build vs CONFIG_MODULE_SRCVERSION

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Message-ID: <176958996819.510.12398407624380709658.tip-bot2@tip-bot2>
Date: Wed, 28 Jan 2026 08:46:08 -0000
From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Song Liu <song@...nel.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: objtool/urgent] livepatch/klp-build: Fix klp-build vs
 CONFIG_MODULE_SRCVERSION_ALL

The following commit has been merged into the objtool/urgent branch of tip:

Commit-ID:     78c268f3781e4b9706103def0cc011505e0c4332
Gitweb:        https://git.kernel.org/tip/78c268f3781e4b9706103def0cc011505e0c4332
Author:        Josh Poimboeuf <jpoimboe@...nel.org>
AuthorDate:    Mon, 26 Jan 2026 15:56:44 -08:00
Committer:     Josh Poimboeuf <jpoimboe@...nel.org>
CommitterDate: Tue, 27 Jan 2026 08:20:51 -08:00

livepatch/klp-build: Fix klp-build vs CONFIG_MODULE_SRCVERSION_ALL

When building a patch to a single-file kernel module with
CONFIG_MODULE_SRCVERSION_ALL enabled, the klp-build module link fails in
modpost:

  Diffing objects
  drivers/md/raid0.o: changed function: raid0_run
  Building patch module: livepatch-0001-patch-raid0_run.ko
  drivers/md/raid0.c: No such file or directory
  ...

The problem here is that klp-build copied drivers/md/.raid0.o.cmd to the
module build directory, but it didn't also copy over the input source
file listed in the .cmd file:

  source_drivers/md/raid0.o := drivers/md/raid0.c

So modpost dies due to the missing .c file which is needed for
calculating checksums for CONFIG_MODULE_SRCVERSION_ALL.

Instead of copying the original .cmd file, just create an empty one.
Modpost only requires that it exists.  The original object's build
dependencies are irrelevant for the frankenobjects used by klp-build.

Fixes: 24ebfcd65a87 ("livepatch/klp-build: Introduce klp-build script for generating livepatch modules")
Reported-by: Song Liu <song@...nel.org>
Tested-by: Song Liu <song@...nel.org>
Link: https://patch.msgid.link/c41b6629e02775e4c1015259aa36065b3fe2f0f3.1769471792.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 scripts/livepatch/klp-build | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index 8822721..a73515a 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -555,13 +555,11 @@ copy_orig_objects() {
 		local file_dir="$(dirname "$file")"
 		local orig_file="$ORIG_DIR/$rel_file"
 		local orig_dir="$(dirname "$orig_file")"
-		local cmd_file="$file_dir/.$(basename "$file").cmd"
 
 		[[ ! -f "$file" ]] && die "missing $(basename "$file") for $_file"
 
 		mkdir -p "$orig_dir"
 		cp -f "$file" "$orig_dir"
-		[[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$orig_dir"
 	done
 	xtrace_restore
 
@@ -740,15 +738,17 @@ build_patch_module() {
 		local orig_dir="$(dirname "$orig_file")"
 		local kmod_file="$KMOD_DIR/$rel_file"
 		local kmod_dir="$(dirname "$kmod_file")"
-		local cmd_file="$orig_dir/.$(basename "$file").cmd"
+		local cmd_file="$kmod_dir/.$(basename "$file").cmd"
 
 		mkdir -p "$kmod_dir"
 		cp -f "$file" "$kmod_dir"
-		[[ -e "$cmd_file" ]] && cp -f "$cmd_file" "$kmod_dir"
 
 		# Tell kbuild this is a prebuilt object
 		cp -f "$file" "${kmod_file}_shipped"
 
+		# Make modpost happy
+		touch "$cmd_file"
+
 		echo -n " $rel_file" >> "$makefile"
 	done