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, 257 insertions, 0 deletions

diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
new file mode 100644
index 000000000..751645645
--- /dev/null
+++ b/lib/test_hexdump.c
@@ -0,0 +1,257 @@
+/*
+ * Test cases for lib/hexdump.c module.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/string.h>
+
+static const unsigned char data_b[] = {
+	'\xbe', '\x32', '\xdb', '\x7b', '\x0a', '\x18', '\x93', '\xb2',	/* 00 - 07 */
+	'\x70', '\xba', '\xc4', '\x24', '\x7d', '\x83', '\x34', '\x9b',	/* 08 - 0f */
+	'\xa6', '\x9c', '\x31', '\xad', '\x9c', '\x0f', '\xac', '\xe9',	/* 10 - 17 */
+	'\x4c', '\xd1', '\x19', '\x99', '\x43', '\xb1', '\xaf', '\x0c',	/* 18 - 1f */
+};
+
+static const unsigned char data_a[] = ".2.{....p..$}.4...1.....L...C...";
+
+static const char * const test_data_1[] __initconst = {
+	"be", "32", "db", "7b", "0a", "18", "93", "b2",
+	"70", "ba", "c4", "24", "7d", "83", "34", "9b",
+	"a6", "9c", "31", "ad", "9c", "0f", "ac", "e9",
+	"4c", "d1", "19", "99", "43", "b1", "af", "0c",
+};
+
+static const char * const test_data_2_le[] __initconst = {
+	"32be", "7bdb", "180a", "b293",
+	"ba70", "24c4", "837d", "9b34",
+	"9ca6", "ad31", "0f9c", "e9ac",
+	"d14c", "9919", "b143", "0caf",
+};
+
+static const char * const test_data_2_be[] __initconst = {
+	"be32", "db7b", "0a18", "93b2",
+	"70ba", "c424", "7d83", "349b",
+	"a69c", "31ad", "9c0f", "ace9",
+	"4cd1", "1999", "43b1", "af0c",
+};
+
+static const char * const test_data_4_le[] __initconst = {
+	"7bdb32be", "b293180a", "24c4ba70", "9b34837d",
+	"ad319ca6", "e9ac0f9c", "9919d14c", "0cafb143",
+};
+
+static const char * const test_data_4_be[] __initconst = {
+	"be32db7b", "0a1893b2", "70bac424", "7d83349b",
+	"a69c31ad", "9c0face9", "4cd11999", "43b1af0c",
+};
+
+static const char * const test_data_8_le[] __initconst = {
+	"b293180a7bdb32be", "9b34837d24c4ba70",
+	"e9ac0f9cad319ca6", "0cafb1439919d14c",
+};
+
+static const char * const test_data_8_be[] __initconst = {
+	"be32db7b0a1893b2", "70bac4247d83349b",
+	"a69c31ad9c0face9", "4cd1199943b1af0c",
+};
+
+#define FILL_CHAR	'#'
+
+static unsigned total_tests __initdata;
+static unsigned failed_tests __initdata;
+
+static void __init test_hexdump_prepare_test(size_t len, int rowsize,
+					     int groupsize, char *test,
+					     size_t testlen, bool ascii)
+{
+	char *p;
+	const char * const *result;
+	size_t l = len;
+	int gs = groupsize, rs = rowsize;
+	unsigned int i;
+	const bool is_be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
+
+	if (rs != 16 && rs != 32)
+		rs = 16;
+
+	if (l > rs)
+		l = rs;
+
+	if (!is_power_of_2(gs) || gs > 8 || (len % gs != 0))
+		gs = 1;
+
+	if (gs == 8)
+		result = is_be ? test_data_8_be : test_data_8_le;
+	else if (gs == 4)
+		result = is_be ? test_data_4_be : test_data_4_le;
+	else if (gs == 2)
+		result = is_be ? test_data_2_be : test_data_2_le;
+	else
+		result = test_data_1;
+
+	/* hex dump */
+	p = test;
+	for (i = 0; i < l / gs; i++) {
+		const char *q = *result++;
+		size_t amount = strlen(q);
+
+		memcpy(p, q, amount);
+		p += amount;
+
+		*p++ = ' ';
+	}
+	if (i)
+		p--;
+
+	/* ASCII part */
+	if (ascii) {
+		do {
+			*p++ = ' ';
+		} while (p < test + rs * 2 + rs / gs + 1);
+
+		memcpy(p, data_a, l);
+		p += l;
+	}
+
+	*p = '\0';
+}
+
+#define TEST_HEXDUMP_BUF_SIZE		(32 * 3 + 2 + 32 + 1)
+
+static void __init test_hexdump(size_t len, int rowsize, int groupsize,
+				bool ascii)
+{
+	char test[TEST_HEXDUMP_BUF_SIZE];
+	char real[TEST_HEXDUMP_BUF_SIZE];
+
+	total_tests++;
+
+	memset(real, FILL_CHAR, sizeof(real));
+	hex_dump_to_buffer(data_b, len, rowsize, groupsize, real, sizeof(real),
+			   ascii);
+
+	memset(test, FILL_CHAR, sizeof(test));
+	test_hexdump_prepare_test(len, rowsize, groupsize, test, sizeof(test),
+				  ascii);
+
+	if (memcmp(test, real, TEST_HEXDUMP_BUF_SIZE)) {
+		pr_err("Len: %zu row: %d group: %d\n", len, rowsize, groupsize);
+		pr_err("Result: '%s'\n", real);
+		pr_err("Expect: '%s'\n", test);
+		failed_tests++;
+	}
+}
+
+static void __init test_hexdump_set(int rowsize, bool ascii)
+{
+	size_t d = min_t(size_t, sizeof(data_b), rowsize);
+	size_t len = get_random_u32_inclusive(1, d);
+
+	test_hexdump(len, rowsize, 4, ascii);
+	test_hexdump(len, rowsize, 2, ascii);
+	test_hexdump(len, rowsize, 8, ascii);
+	test_hexdump(len, rowsize, 1, ascii);
+}
+
+static void __init test_hexdump_overflow(size_t buflen, size_t len,
+					 int rowsize, int groupsize,
+					 bool ascii)
+{
+	char test[TEST_HEXDUMP_BUF_SIZE];
+	char buf[TEST_HEXDUMP_BUF_SIZE];
+	int rs = rowsize, gs = groupsize;
+	int ae, he, e, f, r;
+	bool a;
+
+	total_tests++;
+
+	memset(buf, FILL_CHAR, sizeof(buf));
+
+	r = hex_dump_to_buffer(data_b, len, rs, gs, buf, buflen, ascii);
+
+	/*
+	 * Caller must provide the data length multiple of groupsize. The
+	 * calculations below are made with that assumption in mind.
+	 */
+	ae = rs * 2 /* hex */ + rs / gs /* spaces */ + 1 /* space */ + len /* ascii */;
+	he = (gs * 2 /* hex */ + 1 /* space */) * len / gs - 1 /* no trailing space */;
+
+	if (ascii)
+		e = ae;
+	else
+		e = he;
+
+	f = min_t(int, e + 1, buflen);
+	if (buflen) {
+		test_hexdump_prepare_test(len, rs, gs, test, sizeof(test), ascii);
+		test[f - 1] = '\0';
+	}
+	memset(test + f, FILL_CHAR, sizeof(test) - f);
+
+	a = r == e && !memcmp(test, buf, TEST_HEXDUMP_BUF_SIZE);
+
+	buf[sizeof(buf) - 1] = '\0';
+
+	if (!a) {
+		pr_err("Len: %zu buflen: %zu strlen: %zu\n",
+			len, buflen, strnlen(buf, sizeof(buf)));
+		pr_err("Result: %d '%s'\n", r, buf);
+		pr_err("Expect: %d '%s'\n", e, test);
+		failed_tests++;
+	}
+}
+
+static void __init test_hexdump_overflow_set(size_t buflen, bool ascii)
+{
+	unsigned int i = 0;
+	int rs = get_random_u32_inclusive(1, 2) * 16;
+
+	do {
+		int gs = 1 << i;
+		size_t len = get_random_u32_below(rs) + gs;
+
+		test_hexdump_overflow(buflen, rounddown(len, gs), rs, gs, ascii);
+	} while (i++ < 3);
+}
+
+static int __init test_hexdump_init(void)
+{
+	unsigned int i;
+	int rowsize;
+
+	rowsize = get_random_u32_inclusive(1, 2) * 16;
+	for (i = 0; i < 16; i++)
+		test_hexdump_set(rowsize, false);
+
+	rowsize = get_random_u32_inclusive(1, 2) * 16;
+	for (i = 0; i < 16; i++)
+		test_hexdump_set(rowsize, true);
+
+	for (i = 0; i <= TEST_HEXDUMP_BUF_SIZE; i++)
+		test_hexdump_overflow_set(i, false);
+
+	for (i = 0; i <= TEST_HEXDUMP_BUF_SIZE; i++)
+		test_hexdump_overflow_set(i, true);
+
+	if (failed_tests == 0)
+		pr_info("all %u tests passed\n", total_tests);
+	else
+		pr_err("failed %u out of %u tests\n", failed_tests, total_tests);
+
+	return failed_tests ? -EINVAL : 0;
+}
+module_init(test_hexdump_init);
+
+static void __exit test_hexdump_exit(void)
+{
+	/* do nothing */
+}
+module_exit(test_hexdump_exit);
+
+MODULE_AUTHOR("Andy Shevchenko <andriy.shevchenko@linux.intel.com>");
+MODULE_DESCRIPTION("Test cases for lib/hexdump.c module");
+MODULE_LICENSE("Dual BSD/GPL");