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>

4 files changed, 193 insertions, 0 deletions

diff --git a/arch/mips/n64/Makefile b/arch/mips/n64/Makefile
new file mode 100644
index 000000000..b64a05ae2
--- /dev/null
+++ b/arch/mips/n64/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Nintendo 64
+#
+
+obj-y := init.o irq.o
diff --git a/arch/mips/n64/Platform b/arch/mips/n64/Platform
new file mode 100644
index 000000000..246478313
--- /dev/null
+++ b/arch/mips/n64/Platform
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Nintendo 64
+#
+
+cflags-$(CONFIG_MACH_NINTENDO64)    += -I$(srctree)/arch/mips/include/asm/mach-n64
+load-$(CONFIG_MACH_NINTENDO64)      += 0xffffffff80101000
diff --git a/arch/mips/n64/init.c b/arch/mips/n64/init.c
new file mode 100644
index 000000000..66ec28ab4
--- /dev/null
+++ b/arch/mips/n64/init.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Nintendo 64 init.
+ *
+ *  Copyright (C) 2021	Lauri Kasanen
+ */
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/memblock.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/string.h>
+
+#include <asm/bootinfo.h>
+#include <asm/fw/fw.h>
+#include <asm/time.h>
+
+#define IO_MEM_RESOURCE_START	0UL
+#define IO_MEM_RESOURCE_END	0x1fffffffUL
+
+/*
+ * System-specifc irq names for clarity
+ */
+#define MIPS_CPU_IRQ(x)		(MIPS_CPU_IRQ_BASE + (x))
+#define MIPS_SOFTINT0_IRQ	MIPS_CPU_IRQ(0)
+#define MIPS_SOFTINT1_IRQ	MIPS_CPU_IRQ(1)
+#define RCP_IRQ			MIPS_CPU_IRQ(2)
+#define CART_IRQ		MIPS_CPU_IRQ(3)
+#define PRENMI_IRQ		MIPS_CPU_IRQ(4)
+#define RDBR_IRQ		MIPS_CPU_IRQ(5)
+#define RDBW_IRQ		MIPS_CPU_IRQ(6)
+#define TIMER_IRQ		MIPS_CPU_IRQ(7)
+
+static void __init iomem_resource_init(void)
+{
+	iomem_resource.start = IO_MEM_RESOURCE_START;
+	iomem_resource.end = IO_MEM_RESOURCE_END;
+}
+
+const char *get_system_type(void)
+{
+	return "Nintendo 64";
+}
+
+void __init prom_init(void)
+{
+	fw_init_cmdline();
+}
+
+#define W 320
+#define H 240
+#define REG_BASE ((u32 __iomem *) CKSEG1ADDR(0x4400000))
+
+static void __init n64rdp_write_reg(const u8 reg, const u32 value)
+{
+	__raw_writel(value, REG_BASE + reg);
+}
+
+#undef REG_BASE
+
+static const u32 ntsc_320[] __initconst = {
+	0x00013212, 0x00000000, 0x00000140, 0x00000200,
+	0x00000000, 0x03e52239, 0x0000020d, 0x00000c15,
+	0x0c150c15, 0x006c02ec, 0x002501ff, 0x000e0204,
+	0x00000200, 0x00000400
+};
+
+#define MI_REG_BASE 0x4300000
+#define NUM_MI_REGS 4
+#define AI_REG_BASE 0x4500000
+#define NUM_AI_REGS 6
+#define PI_REG_BASE 0x4600000
+#define NUM_PI_REGS 5
+#define SI_REG_BASE 0x4800000
+#define NUM_SI_REGS 7
+
+static int __init n64_platform_init(void)
+{
+	static const char simplefb_resname[] = "FB";
+	static const struct simplefb_platform_data mode = {
+		.width = W,
+		.height = H,
+		.stride = W * 2,
+		.format = "r5g5b5a1"
+	};
+	struct resource res[3];
+	void *orig;
+	unsigned long phys;
+	unsigned i;
+
+	memset(res, 0, sizeof(struct resource) * 3);
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = MI_REG_BASE;
+	res[0].end = MI_REG_BASE + NUM_MI_REGS * 4 - 1;
+
+	res[1].flags = IORESOURCE_MEM;
+	res[1].start = AI_REG_BASE;
+	res[1].end = AI_REG_BASE + NUM_AI_REGS * 4 - 1;
+
+	res[2].flags = IORESOURCE_IRQ;
+	res[2].start = RCP_IRQ;
+	res[2].end = RCP_IRQ;
+
+	platform_device_register_simple("n64audio", -1, res, 3);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = PI_REG_BASE;
+	res[0].end = PI_REG_BASE + NUM_PI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64cart", -1, res, 1);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = SI_REG_BASE;
+	res[0].end = SI_REG_BASE + NUM_SI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64joy", -1, res, 1);
+
+	/* The framebuffer needs 64-byte alignment */
+	orig = kzalloc(W * H * 2 + 63, GFP_DMA | GFP_KERNEL);
+	if (!orig)
+		return -ENOMEM;
+	phys = virt_to_phys(orig);
+	phys += 63;
+	phys &= ~63;
+
+	for (i = 0; i < ARRAY_SIZE(ntsc_320); i++) {
+		if (i == 1)
+			n64rdp_write_reg(i, phys);
+		else
+			n64rdp_write_reg(i, ntsc_320[i]);
+	}
+
+	/* setup IORESOURCE_MEM as framebuffer memory */
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].name = simplefb_resname;
+	res[0].start = phys;
+	res[0].end = phys + W * H * 2 - 1;
+
+	platform_device_register_resndata(NULL, "simple-framebuffer", 0,
+					  &res[0], 1, &mode, sizeof(mode));
+
+	return 0;
+}
+
+#undef W
+#undef H
+
+arch_initcall(n64_platform_init);
+
+void __init plat_mem_setup(void)
+{
+	iomem_resource_init();
+	memblock_add(0x0, 8 * 1024 * 1024); /* Bootloader blocks the 4mb config */
+}
+
+void __init plat_time_init(void)
+{
+	/* 93.75 MHz cpu, count register runs at half rate */
+	mips_hpt_frequency = 93750000 / 2;
+}
diff --git a/arch/mips/n64/irq.c b/arch/mips/n64/irq.c
new file mode 100644
index 000000000..1861e962d
--- /dev/null
+++ b/arch/mips/n64/irq.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  N64 IRQ
+ *
+ *  Copyright (C) 2021 Lauri Kasanen
+ */
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+
+#include <asm/irq_cpu.h>
+
+void __init arch_init_irq(void)
+{
+	mips_cpu_irq_init();
+}