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, 115 insertions, 0 deletions

diff --git a/drivers/misc/cb710/debug.c b/drivers/misc/cb710/debug.c
new file mode 100644
index 000000000..20d672edf
--- /dev/null
+++ b/drivers/misc/cb710/debug.c
@@ -0,0 +1,115 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  cb710/debug.c
+ *
+ *  Copyright by Michał Mirosław, 2008-2009
+ */
+#include <linux/cb710.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define CB710_REG_COUNT		0x80
+
+static const u16 allow[CB710_REG_COUNT/16] = {
+	0xFFF0, 0xFFFF, 0xFFFF, 0xFFFF,
+	0xFFF0, 0xFFFF, 0xFFFF, 0xFFFF,
+};
+static const char *const prefix[ARRAY_SIZE(allow)] = {
+	"MMC", "MMC", "MMC", "MMC",
+	"MS?", "MS?", "SM?", "SM?"
+};
+
+static inline int allow_reg_read(unsigned block, unsigned offset, unsigned bits)
+{
+	unsigned mask = (1 << bits/8) - 1;
+	offset *= bits/8;
+	return ((allow[block] >> offset) & mask) == mask;
+}
+
+#define CB710_READ_REGS_TEMPLATE(t)					\
+static void cb710_read_regs_##t(void __iomem *iobase,			\
+	u##t *reg, unsigned select)					\
+{									\
+	unsigned i, j;							\
+									\
+	for (i = 0; i < ARRAY_SIZE(allow); ++i, reg += 16/(t/8)) {	\
+		if (!(select & (1 << i)))					\
+			continue;					\
+									\
+		for (j = 0; j < 0x10/(t/8); ++j) {			\
+			if (!allow_reg_read(i, j, t))			\
+				continue;				\
+			reg[j] = ioread##t(iobase			\
+				+ (i << 4) + (j * (t/8)));		\
+		}							\
+	}								\
+}
+
+static const char cb710_regf_8[] = "%02X";
+static const char cb710_regf_16[] = "%04X";
+static const char cb710_regf_32[] = "%08X";
+static const char cb710_xes[] = "xxxxxxxx";
+
+#define CB710_DUMP_REGS_TEMPLATE(t)					\
+static void cb710_dump_regs_##t(struct device *dev,			\
+	const u##t *reg, unsigned select)				\
+{									\
+	const char *const xp = &cb710_xes[8 - t/4];			\
+	const char *const format = cb710_regf_##t;			\
+									\
+	char msg[100], *p;						\
+	unsigned i, j;							\
+									\
+	for (i = 0; i < ARRAY_SIZE(allow); ++i, reg += 16/(t/8)) {	\
+		if (!(select & (1 << i)))				\
+			continue;					\
+		p = msg;						\
+		for (j = 0; j < 0x10/(t/8); ++j) {			\
+			*p++ = ' ';					\
+			if (j == 8/(t/8))				\
+				*p++ = ' ';				\
+			if (allow_reg_read(i, j, t))			\
+				p += sprintf(p, format, reg[j]);	\
+			else						\
+				p += sprintf(p, "%s", xp);		\
+		}							\
+		dev_dbg(dev, "%s 0x%02X %s\n", prefix[i], i << 4, msg);	\
+	}								\
+}
+
+#define CB710_READ_AND_DUMP_REGS_TEMPLATE(t)				\
+static void cb710_read_and_dump_regs_##t(struct cb710_chip *chip,	\
+	unsigned select)						\
+{									\
+	u##t regs[CB710_REG_COUNT/sizeof(u##t)];			\
+									\
+	memset(&regs, 0, sizeof(regs));					\
+	cb710_read_regs_##t(chip->iobase, regs, select);		\
+	cb710_dump_regs_##t(cb710_chip_dev(chip), regs, select);	\
+}
+
+#define CB710_REG_ACCESS_TEMPLATES(t)		\
+  CB710_READ_REGS_TEMPLATE(t)			\
+  CB710_DUMP_REGS_TEMPLATE(t)			\
+  CB710_READ_AND_DUMP_REGS_TEMPLATE(t)
+
+CB710_REG_ACCESS_TEMPLATES(8)
+CB710_REG_ACCESS_TEMPLATES(16)
+CB710_REG_ACCESS_TEMPLATES(32)
+
+void cb710_dump_regs(struct cb710_chip *chip, unsigned select)
+{
+	if (!(select & CB710_DUMP_REGS_MASK))
+		select = CB710_DUMP_REGS_ALL;
+	if (!(select & CB710_DUMP_ACCESS_MASK))
+		select |= CB710_DUMP_ACCESS_8;
+
+	if (select & CB710_DUMP_ACCESS_32)
+		cb710_read_and_dump_regs_32(chip, select);
+	if (select & CB710_DUMP_ACCESS_16)
+		cb710_read_and_dump_regs_16(chip, select);
+	if (select & CB710_DUMP_ACCESS_8)
+		cb710_read_and_dump_regs_8(chip, select);
+}
+EXPORT_SYMBOL_GPL(cb710_dump_regs);
+