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, 88 insertions, 0 deletions

diff --git a/lib/crc/gen_crc64table.c b/lib/crc/gen_crc64table.c
new file mode 100644
index 000000000..f2be9f62b
--- /dev/null
+++ b/lib/crc/gen_crc64table.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This host program runs at kernel build time and generates the lookup tables
+ * used by the generic CRC64 code.
+ *
+ * Copyright 2018 SUSE Linux.
+ *   Author: Coly Li <colyli@suse.de>
+ */
+#include <inttypes.h>
+#include <stdio.h>
+
+#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL
+#define CRC64_NVME_POLY 0x9A6C9329AC4BC9B5ULL
+
+static uint64_t crc64_table[256] = {0};
+static uint64_t crc64_nvme_table[256] = {0};
+
+static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly)
+{
+	uint64_t i, j, c, crc;
+
+	for (i = 0; i < 256; i++) {
+		crc = 0ULL;
+		c = i;
+
+		for (j = 0; j < 8; j++) {
+			if ((crc ^ (c >> j)) & 1)
+				crc = (crc >> 1) ^ poly;
+			else
+				crc >>= 1;
+		}
+		table[i] = crc;
+	}
+}
+
+static void generate_crc64_table(uint64_t table[256], uint64_t poly)
+{
+	uint64_t i, j, c, crc;
+
+	for (i = 0; i < 256; i++) {
+		crc = 0;
+		c = i << 56;
+
+		for (j = 0; j < 8; j++) {
+			if ((crc ^ c) & 0x8000000000000000ULL)
+				crc = (crc << 1) ^ poly;
+			else
+				crc <<= 1;
+			c <<= 1;
+		}
+
+		table[i] = crc;
+	}
+}
+
+static void output_table(uint64_t table[256])
+{
+	int i;
+
+	for (i = 0; i < 256; i++) {
+		printf("\t0x%016" PRIx64 "ULL", table[i]);
+		if (i & 0x1)
+			printf(",\n");
+		else
+			printf(", ");
+	}
+	printf("};\n");
+}
+
+static void print_crc64_tables(void)
+{
+	printf("/* this file is generated - do not edit */\n\n");
+	printf("#include <linux/types.h>\n");
+	printf("#include <linux/cache.h>\n\n");
+	printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");
+	output_table(crc64_table);
+
+	printf("\nstatic const u64 ____cacheline_aligned crc64nvmetable[256] = {\n");
+	output_table(crc64_nvme_table);
+}
+
+int main(int argc, char *argv[])
+{
+	generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);
+	generate_reflected_crc64_table(crc64_nvme_table, CRC64_NVME_POLY);
+	print_crc64_tables();
+	return 0;
+}