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, 78 insertions, 0 deletions

diff --git a/scripts/ld-version.sh b/scripts/ld-version.sh
new file mode 100755
index 000000000..b9513d224
--- /dev/null
+++ b/scripts/ld-version.sh
@@ -0,0 +1,78 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Print the linker name and its version in a 5 or 6-digit form.
+# Also, perform the minimum version check.
+
+set -e
+
+# Convert the version string x.y.z to a canonical 5 or 6-digit form.
+get_canonical_version()
+{
+	IFS=.
+	set -- $1
+
+	# If the 2nd or 3rd field is missing, fill it with a zero.
+	#
+	# The 4th field, if present, is ignored.
+	# This occurs in development snapshots as in 2.35.1.20201116
+	echo $((10000 * $1 + 100 * ${2:-0} + ${3:-0}))
+}
+
+orig_args="$@"
+
+# Get the first line of the --version output.
+IFS='
+'
+set -- $(LC_ALL=C "$@" --version)
+
+# Split the line on spaces.
+IFS=' '
+set -- $1
+
+min_tool_version=$(dirname $0)/min-tool-version.sh
+
+if [ "$1" = GNU -a "$2" = ld ]; then
+	shift $(($# - 1))
+	version=$1
+	min_version=$($min_tool_version binutils)
+	name=BFD
+	disp_name="GNU ld"
+elif [ "$1" = GNU -a "$2" = gold ]; then
+	echo "gold linker is not supported as it is not capable of linking the kernel proper." >&2
+	exit 1
+else
+	while [ $# -gt 1 -a "$1" != "LLD" ]; do
+		shift
+	done
+
+	if [ "$1" = LLD ]; then
+		version=$2
+		min_version=$($min_tool_version llvm)
+		name=LLD
+		disp_name=LLD
+	else
+		echo "$orig_args: unknown linker" >&2
+		exit 1
+	fi
+fi
+
+# There may be something after the version, such as a distribution's package
+# release number (like Fedora's "2.34-4.fc32") or punctuation (like LLD briefly
+# added before the "compatible with GNU linkers" string), so remove everything
+# after just numbers and periods.
+version=${version%%[!0-9.]*}
+
+cversion=$(get_canonical_version $version)
+min_cversion=$(get_canonical_version $min_version)
+
+if [ "$cversion" -lt "$min_cversion" ]; then
+	echo >&2 "***"
+	echo >&2 "*** Linker is too old."
+	echo >&2 "***   Your $disp_name version:    $version"
+	echo >&2 "***   Minimum $disp_name version: $min_version"
+	echo >&2 "***"
+	exit 1
+fi
+
+echo $name $cversion