ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 162 insertions, 0 deletions

diff --git a/scripts/objdiff b/scripts/objdiff
new file mode 100755
index 000000000..0685bc3ce
--- /dev/null
+++ b/scripts/objdiff
@@ -0,0 +1,162 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-only
+
+# objdiff - a small script for validating that a commit or series of commits
+# didn't change object code.
+#
+# Copyright 2014, Jason Cooper <jason@lakedaemon.net>
+#
+
+# usage example:
+#
+# $ git checkout COMMIT_A
+# $ <your fancy build command here>
+# $ ./scripts/objdiff record path/to/*.o
+#
+# $ git checkout COMMIT_B
+# $ <your fancy build command here>
+# $ ./scripts/objdiff record path/to/*.o
+#
+# $ ./scripts/objdiff diff COMMIT_A COMMIT_B
+# $
+
+# And to clean up (everything is in .objdiff/*)
+# $ ./scripts/objdiff clean all
+#
+# Note: 'make mrproper' will also remove .objdiff
+
+SRCTREE=$(cd $(git rev-parse --show-toplevel 2>/dev/null); pwd)
+
+if [ -z "$SRCTREE" ]; then
+	echo >&2 "ERROR: Not a git repository."
+	exit 1
+fi
+
+TMPD=$SRCTREE/.objdiff
+
+usage() {
+	echo >&2 "Usage: $0 <command> <args>"
+	echo >&2 "  record    <list of object files or directories>"
+	echo >&2 "  diff      <commitA> <commitB>"
+	echo >&2 "  clean     all | <commit>"
+	exit 1
+}
+
+get_output_dir() {
+	dir=${1%/*}
+
+	if [ "$dir" = "$1" ]; then
+		dir=.
+	fi
+
+	dir=$(cd $dir; pwd)
+
+	echo $TMPD/$CMT${dir#$SRCTREE}
+}
+
+do_objdump() {
+	dir=$(get_output_dir $1)
+	base=${1##*/}
+	stripped=$dir/${base%.o}.stripped
+	dis=$dir/${base%.o}.dis
+
+	[ ! -d "$dir" ] && mkdir -p $dir
+
+	# remove addresses for a cleaner diff
+	# http://dummdida.tumblr.com/post/60924060451/binary-diff-between-libc-from-scientificlinux-and
+	$STRIP -g $1 -R __bug_table -R .note -R .comment -o $stripped
+	$OBJDUMP -D $stripped | sed -e "s/^[[:space:]]\+[0-9a-f]\+//" -e "s:^$stripped:$1:" > $dis
+}
+
+dorecord() {
+	[ $# -eq 0 ] && usage
+
+	FILES="$*"
+
+	CMT="`git rev-parse --short HEAD`"
+
+	STRIP="${CROSS_COMPILE}strip"
+	OBJDUMP="${CROSS_COMPILE}objdump"
+
+	for d in $FILES; do
+		if [ -d "$d" ]; then
+			for f in $(find $d -name '*.o')
+			do
+				do_objdump $f
+			done
+		else
+			do_objdump $d
+		fi
+	done
+}
+
+dodiff() {
+	[ $# -ne 2 ] && [ $# -ne 0 ] && usage
+
+	if [ $# -eq 0 ]; then
+		SRC="`git rev-parse --short HEAD^`"
+		DST="`git rev-parse --short HEAD`"
+	else
+		SRC="`git rev-parse --short $1`"
+		DST="`git rev-parse --short $2`"
+	fi
+
+	DIFF="`which colordiff`"
+
+	if [ ${#DIFF} -eq 0 ] || [ ! -x "$DIFF" ]; then
+		DIFF="`which diff`"
+	fi
+
+	SRCD="$TMPD/$SRC"
+	DSTD="$TMPD/$DST"
+
+	if [ ! -d "$SRCD" ]; then
+		echo >&2 "ERROR: $SRCD doesn't exist"
+		exit 1
+	fi
+
+	if [ ! -d "$DSTD" ]; then
+		echo >&2 "ERROR: $DSTD doesn't exist"
+		exit 1
+	fi
+
+	$DIFF -Nurd $SRCD $DSTD
+}
+
+doclean() {
+	[ $# -eq 0 ] && usage
+	[ $# -gt 1 ] && usage
+
+	if [ "x$1" = "xall" ]; then
+		rm -rf $TMPD/*
+	else
+		CMT="`git rev-parse --short $1`"
+
+		if [ -d "$TMPD/$CMT" ]; then
+			rm -rf $TMPD/$CMT
+		else
+			echo >&2 "$CMT not found"
+		fi
+	fi
+}
+
+[ $# -eq 0 ] &&	usage
+
+case "$1" in
+	record)
+		shift
+		dorecord $*
+		;;
+	diff)
+		shift
+		dodiff $*
+		;;
+	clean)
+		shift
+		doclean $*
+		;;
+	*)
+		echo >&2 "Unrecognized command '$1'"
+		exit 1
+		;;
+esac