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, 65 insertions, 0 deletions

diff --git a/drivers/tty/serial/apbuart.h b/drivers/tty/serial/apbuart.h
new file mode 100644
index 000000000..81baf0076
--- /dev/null
+++ b/drivers/tty/serial/apbuart.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __GRLIB_APBUART_H__
+#define __GRLIB_APBUART_H__
+
+#include <asm/io.h>
+
+#define UART_NR		8
+static int grlib_apbuart_port_nr;
+
+struct grlib_apbuart_regs_map {
+	u32 data;
+	u32 status;
+	u32 ctrl;
+	u32 scaler;
+};
+
+struct amba_prom_registers {
+	unsigned int phys_addr;
+	unsigned int reg_size;
+};
+
+/*
+ *  The following defines the bits in the APBUART Status Registers.
+ */
+#define UART_STATUS_DR   0x00000001	/* Data Ready */
+#define UART_STATUS_TSE  0x00000002	/* TX Send Register Empty */
+#define UART_STATUS_THE  0x00000004	/* TX Hold Register Empty */
+#define UART_STATUS_BR   0x00000008	/* Break Error */
+#define UART_STATUS_OE   0x00000010	/* RX Overrun Error */
+#define UART_STATUS_PE   0x00000020	/* RX Parity Error */
+#define UART_STATUS_FE   0x00000040	/* RX Framing Error */
+#define UART_STATUS_ERR  0x00000078	/* Error Mask */
+
+/*
+ *  The following defines the bits in the APBUART Ctrl Registers.
+ */
+#define UART_CTRL_RE     0x00000001	/* Receiver enable */
+#define UART_CTRL_TE     0x00000002	/* Transmitter enable */
+#define UART_CTRL_RI     0x00000004	/* Receiver interrupt enable */
+#define UART_CTRL_TI     0x00000008	/* Transmitter irq */
+#define UART_CTRL_PS     0x00000010	/* Parity select */
+#define UART_CTRL_PE     0x00000020	/* Parity enable */
+#define UART_CTRL_FL     0x00000040	/* Flow control enable */
+#define UART_CTRL_LB     0x00000080	/* Loopback enable */
+
+#define APBBASE(port) ((struct grlib_apbuart_regs_map *)((port)->membase))
+
+#define APBBASE_DATA_P(port)	(&(APBBASE(port)->data))
+#define APBBASE_STATUS_P(port)	(&(APBBASE(port)->status))
+#define APBBASE_CTRL_P(port)	(&(APBBASE(port)->ctrl))
+#define APBBASE_SCALAR_P(port)	(&(APBBASE(port)->scaler))
+
+#define UART_GET_CHAR(port)	(__raw_readl(APBBASE_DATA_P(port)))
+#define UART_PUT_CHAR(port, v)	(__raw_writel(v, APBBASE_DATA_P(port)))
+#define UART_GET_STATUS(port)	(__raw_readl(APBBASE_STATUS_P(port)))
+#define UART_PUT_STATUS(port, v)(__raw_writel(v, APBBASE_STATUS_P(port)))
+#define UART_GET_CTRL(port)	(__raw_readl(APBBASE_CTRL_P(port)))
+#define UART_PUT_CTRL(port, v)	(__raw_writel(v, APBBASE_CTRL_P(port)))
+#define UART_GET_SCAL(port)	(__raw_readl(APBBASE_SCALAR_P(port)))
+#define UART_PUT_SCAL(port, v)	(__raw_writel(v, APBBASE_SCALAR_P(port)))
+
+#define UART_RX_DATA(s)		(((s) & UART_STATUS_DR) != 0)
+#define UART_TX_READY(s)	(((s) & UART_STATUS_THE) != 0)
+
+#endif /* __GRLIB_APBUART_H__ */