From 31934047a5fde7054f64e5fbdef814486d76a224 Mon Sep 17 00:00:00 2001
From: Stephen Cheng <stephen.cheng@citrix.com>
Date: Thu, 2 Apr 2026 13:38:10 +0800
Subject: [PATCH] kpatch: support eu-readelf as alternative to GNU readelf

The kpatch script is used to load live patches on production systems
that may be stripped down, with binutils (which provides readelf) not
installed while elfutils (which provides eu-readelf) is available. Add
a get_module_section_string() helper that auto-detects the available
tool at startup and uses the appropriate invocation for each.

Other readelf usages in the build tooling (kpatch-build, lookup.c,
test infrastructure) are left unchanged, as a compiler toolchain
including binutils can reasonably be expected in a build environment.

Signed-off-by: Stephen Cheng <stephen.cheng@citrix.com>
---
 kpatch/kpatch | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/kpatch/kpatch b/kpatch/kpatch
index 4eff2161..a90e29da 100755
--- a/kpatch/kpatch
+++ b/kpatch/kpatch
@@ -134,8 +134,22 @@ core_loaded () {
 	[[ -d "/sys/kernel/kpatch" ]] || [[ -d "/sys/kernel/livepatch" ]]
 }
 
+if command -v readelf >/dev/null 2>&1; then
+	get_module_section_string() {
+		readelf -p "$2" "$1" | awk 'NF>=3 && /^\s*\[/ {print $3; exit}'
+	}
+elif command -v eu-readelf >/dev/null 2>&1; then
+	get_module_section_string() {
+		eu-readelf --string-dump="$2" "$1" | awk 'NF>=3 && /^\s*\[/ {print $3; exit}'
+	}
+else
+	get_module_section_string() {
+		return 1
+	}
+fi
+
 get_module_name () {
-	readelf -p .gnu.linkonce.this_module "$1" | grep '\[.*\]' | awk '{print $3}'
+	get_module_section_string "$1" .gnu.linkonce.this_module
 }
 
 init_sysfs_var() {
@@ -156,10 +170,10 @@ init_sysfs_var() {
 }
 
 verify_module_checksum () {
-	modname="$(get_module_name "$1")"
+	modname="$(get_module_name "$1")" || return 1
 	[[ -z "$modname" ]] && return 1
 
-	checksum="$(readelf -p .kpatch.checksum "$1" 2>&1 | grep '\[.*\]' | awk '{print $3}')"
+	checksum="$(get_module_section_string "$1" .kpatch.checksum 2>/dev/null)" || return 1
 
 	# Fail checksum match only if both exist and diverge
 	if [[ -n "$checksum" ]] && [[ -e "$SYSFS/${modname}/checksum" ]] ; then
@@ -316,7 +330,8 @@ load_module () {
 	fi
 
 	local modname
-	modname="$(get_module_name "$module")"
+	modname="$(get_module_name "$module")" || die "failed to get module name from $module"
+	[[ -z "$modname" ]] && die "failed to get module name from $module"
 	local moddir="$SYSFS/$modname"
 	if [[ -d "$moddir" ]] ; then
 		if [[ "$(cat "${moddir}/enabled")" -eq 0 ]]; then