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, 330 insertions, 0 deletions

diff --git a/lib/math/test_div64.c b/lib/math/test_div64.c
new file mode 100644
index 000000000..3cd699b65
--- /dev/null
+++ b/lib/math/test_div64.c
@@ -0,0 +1,330 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021  Maciej W. Rozycki
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/time64.h>
+#include <linux/types.h>
+
+#include <asm/div64.h>
+
+#define TEST_DIV64_N_ITER 1024
+
+static const u64 test_div64_dividends[] = {
+	0x00000000ab275080,
+	0x0000000fe73c1959,
+	0x000000e54c0a74b1,
+	0x00000d4398ff1ef9,
+	0x0000a18c2ee1c097,
+	0x00079fb80b072e4a,
+	0x0072db27380dd689,
+	0x0842f488162e2284,
+	0xf66745411d8ab063,
+	0xfffffffffffffffb,
+	0xfffffffffffffffc,
+	0xffffffffffffffff,
+};
+#define SIZE_DIV64_DIVIDENDS ARRAY_SIZE(test_div64_dividends)
+
+#define TEST_DIV64_DIVISOR_0 0x00000009
+#define TEST_DIV64_DIVISOR_1 0x0000007c
+#define TEST_DIV64_DIVISOR_2 0x00000204
+#define TEST_DIV64_DIVISOR_3 0x0000cb5b
+#define TEST_DIV64_DIVISOR_4 0x00010000
+#define TEST_DIV64_DIVISOR_5 0x0008a880
+#define TEST_DIV64_DIVISOR_6 0x003fd3ae
+#define TEST_DIV64_DIVISOR_7 0x0b658fac
+#define TEST_DIV64_DIVISOR_8 0x80000001
+#define TEST_DIV64_DIVISOR_9 0xdc08b349
+#define TEST_DIV64_DIVISOR_A 0xfffffffe
+#define TEST_DIV64_DIVISOR_B 0xffffffff
+
+static const u32 test_div64_divisors[] = {
+	TEST_DIV64_DIVISOR_0,
+	TEST_DIV64_DIVISOR_1,
+	TEST_DIV64_DIVISOR_2,
+	TEST_DIV64_DIVISOR_3,
+	TEST_DIV64_DIVISOR_4,
+	TEST_DIV64_DIVISOR_5,
+	TEST_DIV64_DIVISOR_6,
+	TEST_DIV64_DIVISOR_7,
+	TEST_DIV64_DIVISOR_8,
+	TEST_DIV64_DIVISOR_9,
+	TEST_DIV64_DIVISOR_A,
+	TEST_DIV64_DIVISOR_B,
+};
+#define SIZE_DIV64_DIVISORS ARRAY_SIZE(test_div64_divisors)
+
+static const struct {
+	u64 quotient;
+	u32 remainder;
+} test_div64_results[SIZE_DIV64_DIVIDENDS][SIZE_DIV64_DIVISORS] = {
+	{
+		{ 0x0000000013045e47, 0x00000001 },
+		{ 0x000000000161596c, 0x00000030 },
+		{ 0x000000000054e9d4, 0x00000130 },
+		{ 0x000000000000d776, 0x0000278e },
+		{ 0x000000000000ab27, 0x00005080 },
+		{ 0x00000000000013c4, 0x0004ce80 },
+		{ 0x00000000000002ae, 0x001e143c },
+		{ 0x000000000000000f, 0x0033e56c },
+		{ 0x0000000000000001, 0x2b27507f },
+		{ 0x0000000000000000, 0xab275080 },
+		{ 0x0000000000000000, 0xab275080 },
+		{ 0x0000000000000000, 0xab275080 },
+	}, {
+		{ 0x00000001c45c02d1, 0x00000000 },
+		{ 0x0000000020d5213c, 0x00000049 },
+		{ 0x0000000007e3d65f, 0x000001dd },
+		{ 0x0000000000140531, 0x000065ee },
+		{ 0x00000000000fe73c, 0x00001959 },
+		{ 0x000000000001d637, 0x0004e5d9 },
+		{ 0x0000000000003fc9, 0x000713bb },
+		{ 0x0000000000000165, 0x029abe7d },
+		{ 0x000000000000001f, 0x673c193a },
+		{ 0x0000000000000012, 0x6e9f7e37 },
+		{ 0x000000000000000f, 0xe73c1977 },
+		{ 0x000000000000000f, 0xe73c1968 },
+	}, {
+		{ 0x000000197a3a0cf7, 0x00000002 },
+		{ 0x00000001d9632e5c, 0x00000021 },
+		{ 0x0000000071c28039, 0x000001cd },
+		{ 0x000000000120a844, 0x0000b885 },
+		{ 0x0000000000e54c0a, 0x000074b1 },
+		{ 0x00000000001a7bb3, 0x00072331 },
+		{ 0x00000000000397ad, 0x0002c61b },
+		{ 0x000000000000141e, 0x06ea2e89 },
+		{ 0x00000000000001ca, 0x4c0a72e7 },
+		{ 0x000000000000010a, 0xab002ad7 },
+		{ 0x00000000000000e5, 0x4c0a767b },
+		{ 0x00000000000000e5, 0x4c0a7596 },
+	}, {
+		{ 0x0000017949e37538, 0x00000001 },
+		{ 0x0000001b62441f37, 0x00000055 },
+		{ 0x0000000694a3391d, 0x00000085 },
+		{ 0x0000000010b2a5d2, 0x0000a753 },
+		{ 0x000000000d4398ff, 0x00001ef9 },
+		{ 0x0000000001882ec6, 0x0005cbf9 },
+		{ 0x000000000035333b, 0x0017abdf },
+		{ 0x00000000000129f1, 0x0ab4520d },
+		{ 0x0000000000001a87, 0x18ff0472 },
+		{ 0x0000000000000f6e, 0x8ac0ce9b },
+		{ 0x0000000000000d43, 0x98ff397f },
+		{ 0x0000000000000d43, 0x98ff2c3c },
+	}, {
+		{ 0x000011f321a74e49, 0x00000006 },
+		{ 0x0000014d8481d211, 0x0000005b },
+		{ 0x0000005025cbd92d, 0x000001e3 },
+		{ 0x00000000cb5e71e3, 0x000043e6 },
+		{ 0x00000000a18c2ee1, 0x0000c097 },
+		{ 0x0000000012a88828, 0x00036c97 },
+		{ 0x000000000287f16f, 0x002c2a25 },
+		{ 0x00000000000e2cc7, 0x02d581e3 },
+		{ 0x0000000000014318, 0x2ee07d7f },
+		{ 0x000000000000bbf4, 0x1ba08c03 },
+		{ 0x000000000000a18c, 0x2ee303af },
+		{ 0x000000000000a18c, 0x2ee26223 },
+	}, {
+		{ 0x0000d8db8f72935d, 0x00000005 },
+		{ 0x00000fbd5aed7a2e, 0x00000002 },
+		{ 0x000003c84b6ea64a, 0x00000122 },
+		{ 0x0000000998fa8829, 0x000044b7 },
+		{ 0x000000079fb80b07, 0x00002e4a },
+		{ 0x00000000e16b20fa, 0x0002a14a },
+		{ 0x000000001e940d22, 0x00353b2e },
+		{ 0x0000000000ab40ac, 0x06fba6ba },
+		{ 0x00000000000f3f70, 0x0af7eeda },
+		{ 0x000000000008debd, 0x72d98365 },
+		{ 0x0000000000079fb8, 0x0b166dba },
+		{ 0x0000000000079fb8, 0x0b0ece02 },
+	}, {
+		{ 0x000cc3045b8fc281, 0x00000000 },
+		{ 0x0000ed1f48b5c9fc, 0x00000079 },
+		{ 0x000038fb9c63406a, 0x000000e1 },
+		{ 0x000000909705b825, 0x00000a62 },
+		{ 0x00000072db27380d, 0x0000d689 },
+		{ 0x0000000d43fce827, 0x00082b09 },
+		{ 0x00000001ccaba11a, 0x0037e8dd },
+		{ 0x000000000a13f729, 0x0566dffd },
+		{ 0x0000000000e5b64e, 0x3728203b },
+		{ 0x000000000085a14b, 0x23d36726 },
+		{ 0x000000000072db27, 0x38f38cd7 },
+		{ 0x000000000072db27, 0x3880b1b0 },
+	}, {
+		{ 0x00eafeb9c993592b, 0x00000001 },
+		{ 0x00110e5befa9a991, 0x00000048 },
+		{ 0x00041947b4a1d36a, 0x000000dc },
+		{ 0x00000a6679327311, 0x0000c079 },
+		{ 0x00000842f488162e, 0x00002284 },
+		{ 0x000000f4459740fc, 0x00084484 },
+		{ 0x0000002122c47bf9, 0x002ca446 },
+		{ 0x00000000b9936290, 0x004979c4 },
+		{ 0x000000001085e910, 0x05a83974 },
+		{ 0x00000000099ca89d, 0x9db446bf },
+		{ 0x000000000842f488, 0x26b40b94 },
+		{ 0x000000000842f488, 0x1e71170c },
+	}, {
+		{ 0x1b60cece589da1d2, 0x00000001 },
+		{ 0x01fcb42be1453f5b, 0x0000004f },
+		{ 0x007a3f2457df0749, 0x0000013f },
+		{ 0x0001363130e3ec7b, 0x000017aa },
+		{ 0x0000f66745411d8a, 0x0000b063 },
+		{ 0x00001c757dfab350, 0x00048863 },
+		{ 0x000003dc4979c652, 0x00224ea7 },
+		{ 0x000000159edc3144, 0x06409ab3 },
+		{ 0x00000001ecce8a7e, 0x30bc25e5 },
+		{ 0x000000011eadfee3, 0xa99c48a8 },
+		{ 0x00000000f6674543, 0x0a593ae9 },
+		{ 0x00000000f6674542, 0x13f1f5a5 },
+	}, {
+		{ 0x1c71c71c71c71c71, 0x00000002 },
+		{ 0x0210842108421084, 0x0000000b },
+		{ 0x007f01fc07f01fc0, 0x000000fb },
+		{ 0x00014245eabf1f9a, 0x0000a63d },
+		{ 0x0000ffffffffffff, 0x0000fffb },
+		{ 0x00001d913cecc509, 0x0007937b },
+		{ 0x00000402c70c678f, 0x0005bfc9 },
+		{ 0x00000016766cb70b, 0x045edf97 },
+		{ 0x00000001fffffffb, 0x80000000 },
+		{ 0x0000000129d84b3a, 0xa2e8fe71 },
+		{ 0x0000000100000001, 0xfffffffd },
+		{ 0x0000000100000000, 0xfffffffb },
+	}, {
+		{ 0x1c71c71c71c71c71, 0x00000003 },
+		{ 0x0210842108421084, 0x0000000c },
+		{ 0x007f01fc07f01fc0, 0x000000fc },
+		{ 0x00014245eabf1f9a, 0x0000a63e },
+		{ 0x0000ffffffffffff, 0x0000fffc },
+		{ 0x00001d913cecc509, 0x0007937c },
+		{ 0x00000402c70c678f, 0x0005bfca },
+		{ 0x00000016766cb70b, 0x045edf98 },
+		{ 0x00000001fffffffc, 0x00000000 },
+		{ 0x0000000129d84b3a, 0xa2e8fe72 },
+		{ 0x0000000100000002, 0x00000000 },
+		{ 0x0000000100000000, 0xfffffffc },
+	}, {
+		{ 0x1c71c71c71c71c71, 0x00000006 },
+		{ 0x0210842108421084, 0x0000000f },
+		{ 0x007f01fc07f01fc0, 0x000000ff },
+		{ 0x00014245eabf1f9a, 0x0000a641 },
+		{ 0x0000ffffffffffff, 0x0000ffff },
+		{ 0x00001d913cecc509, 0x0007937f },
+		{ 0x00000402c70c678f, 0x0005bfcd },
+		{ 0x00000016766cb70b, 0x045edf9b },
+		{ 0x00000001fffffffc, 0x00000003 },
+		{ 0x0000000129d84b3a, 0xa2e8fe75 },
+		{ 0x0000000100000002, 0x00000003 },
+		{ 0x0000000100000001, 0x00000000 },
+	},
+};
+
+static inline bool test_div64_verify(u64 quotient, u32 remainder, int i, int j)
+{
+	return (quotient == test_div64_results[i][j].quotient &&
+		remainder == test_div64_results[i][j].remainder);
+}
+
+/*
+ * This needs to be a macro, because we don't want to rely on the compiler
+ * to do constant propagation, and `do_div' may take a different path for
+ * constants, so we do want to verify that as well.
+ */
+#define test_div64_one(dividend, divisor, i, j) ({			\
+	bool result = true;						\
+	u64 quotient;							\
+	u32 remainder;							\
+									\
+	quotient = dividend;						\
+	remainder = do_div(quotient, divisor);				\
+	if (!test_div64_verify(quotient, remainder, i, j)) {		\
+		pr_err("ERROR: %016llx / %08x => %016llx,%08x\n",	\
+		       dividend, divisor, quotient, remainder);		\
+		pr_err("ERROR: expected value              => %016llx,%08x\n",\
+		       test_div64_results[i][j].quotient,		\
+		       test_div64_results[i][j].remainder);		\
+		result = false;						\
+	}								\
+	result;								\
+})
+
+/*
+ * Run calculation for the same divisor value expressed as a constant
+ * and as a variable, so as to verify the implementation for both cases
+ * should they be handled by different code execution paths.
+ */
+static bool __init test_div64(void)
+{
+	u64 dividend;
+	int i, j;
+
+	for (i = 0; i < SIZE_DIV64_DIVIDENDS; i++) {
+		dividend = test_div64_dividends[i];
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_0, i, 0))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_1, i, 1))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_2, i, 2))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_3, i, 3))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_4, i, 4))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_5, i, 5))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_6, i, 6))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_7, i, 7))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_8, i, 8))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_9, i, 9))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_A, i, 10))
+			return false;
+		if (!test_div64_one(dividend, TEST_DIV64_DIVISOR_B, i, 11))
+			return false;
+		for (j = 0; j < SIZE_DIV64_DIVISORS; j++) {
+			if (!test_div64_one(dividend, test_div64_divisors[j],
+					    i, j))
+				return false;
+		}
+	}
+	return true;
+}
+
+static int __init test_div64_init(void)
+{
+	struct timespec64 ts, ts0, ts1;
+	int i;
+
+	pr_info("Starting 64bit/32bit division and modulo test\n");
+	ktime_get_ts64(&ts0);
+
+	for (i = 0; i < TEST_DIV64_N_ITER; i++)
+		if (!test_div64())
+			break;
+
+	ktime_get_ts64(&ts1);
+	ts = timespec64_sub(ts1, ts0);
+	pr_info("Completed 64bit/32bit division and modulo test, "
+		"%llu.%09lus elapsed\n", ts.tv_sec, ts.tv_nsec);
+
+	return 0;
+}
+
+static void __exit test_div64_exit(void)
+{
+}
+
+module_init(test_div64_init);
+module_exit(test_div64_exit);
+
+MODULE_AUTHOR("Maciej W. Rozycki <macro@orcam.me.uk>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("64bit/32bit division and modulo test module");