linux-kernel - [PATCH v4 61/63] livepatch/klp-build: Add --debug option to show cloning decisions

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Message-ID: <84e14354875d4a6d1e79a434e0af1be27720a91a.1758067943.git.jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:09 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	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>,
	Dylan Hatch <dylanbhatch@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v4 61/63] livepatch/klp-build: Add --debug option to show cloning decisions

Add a --debug option which gets passed to "objtool klp diff" to enable
debug output related to cloning decisions.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 scripts/livepatch/klp-build | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/scripts/livepatch/klp-build b/scripts/livepatch/klp-build
index 01ed0b66bfaff..28ee259ce5f6e 100755
--- a/scripts/livepatch/klp-build
+++ b/scripts/livepatch/klp-build
@@ -20,7 +20,7 @@ set -o nounset
 # This helps keep execution in pipes so pipefail+errexit can catch errors.
 shopt -s lastpipe
 
-unset SKIP_CLEANUP XTRACE
+unset DEBUG_CLONE SKIP_CLEANUP XTRACE
 
 REPLACE=1
 SHORT_CIRCUIT=0
@@ -120,6 +120,7 @@ Options:
    -v, --verbose		Pass V=1 to kernel/module builds
 
 Advanced Options:
+   -d, --debug			Show symbol/reloc cloning decisions
    -S, --short-circuit=STEP	Start at build step (requires prior --keep-tmp)
 				   1|orig	Build original kernel (default)
 				   2|patched	Build patched kernel
@@ -140,8 +141,8 @@ process_args() {
 	local long
 	local args
 
-	short="hj:o:vS:T"
-	long="help,jobs:,output:,no-replace,verbose,short-circuit:,keep-tmp"
+	short="hj:o:vdS:T"
+	long="help,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"
 
 	args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
 		echo; usage; exit
@@ -174,6 +175,11 @@ process_args() {
 				VERBOSE="V=1"
 				shift
 				;;
+			-d | --debug)
+				DEBUG_CLONE=1
+				keep_tmp=1
+				shift
+				;;
 			-S | --short-circuit)
 				[[ ! -d "$TMP_DIR" ]] && die "--short-circuit requires preserved klp-tmp dir"
 				keep_tmp=1
@@ -596,6 +602,7 @@ copy_patched_objects() {
 diff_objects() {
 	local log="$KLP_DIFF_LOG"
 	local files=()
+	local opts=()
 
 	rm -rf "$DIFF_DIR"
 	mkdir -p "$DIFF_DIR"
@@ -603,6 +610,8 @@ diff_objects() {
 	find "$PATCHED_DIR" -type f -name "*.o" | mapfile -t files
 	[[ ${#files[@]} -eq 0 ]] && die "no changes detected"
 
+	[[ -v DEBUG_CLONE ]] && opts=("--debug")
+
 	# Diff all changed objects
 	for file in "${files[@]}"; do
 		local rel_file="${file#"$PATCHED_DIR"/}"
@@ -616,6 +625,7 @@ diff_objects() {
 		cmd=("$SRC/tools/objtool/objtool")
 		cmd+=("klp")
 		cmd+=("diff")
+		(( ${#opts[@]} > 0 )) && cmd+=("${opts[@]}")
 		cmd+=("$orig_file")
 		cmd+=("$patched_file")
 		cmd+=("$out_file")
-- 
2.50.0