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, 165 insertions, 0 deletions

diff --git a/arch/arm/mach-omap1/timer.c b/arch/arm/mach-omap1/timer.c
new file mode 100644
index 000000000..399e6d840
--- /dev/null
+++ b/arch/arm/mach-omap1/timer.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * OMAP1 Dual-Mode Timers - platform device registration
+ *
+ * Contains first level initialization routines which internally
+ * generates timer device information and registers with linux
+ * device model. It also has a low level function to change the timer
+ * input clock source.
+ *
+ * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/
+ * Tarun Kanti DebBarma <tarun.kanti@ti.com>
+ * Thara Gopinath <thara@ti.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/dmtimer-omap.h>
+#include <linux/soc/ti/omap1-io.h>
+
+#include <clocksource/timer-ti-dm.h>
+
+#include "soc.h"
+
+#define OMAP1610_GPTIMER1_BASE		0xfffb1400
+#define OMAP1610_GPTIMER2_BASE		0xfffb1c00
+#define OMAP1610_GPTIMER3_BASE		0xfffb2400
+#define OMAP1610_GPTIMER4_BASE		0xfffb2c00
+#define OMAP1610_GPTIMER5_BASE		0xfffb3400
+#define OMAP1610_GPTIMER6_BASE		0xfffb3c00
+#define OMAP1610_GPTIMER7_BASE		0xfffb7400
+#define OMAP1610_GPTIMER8_BASE		0xfffbd400
+
+#define OMAP1_DM_TIMER_COUNT		8
+
+static int omap1_dm_timer_set_src(struct platform_device *pdev,
+				int source)
+{
+	int n = (pdev->id - 1) << 1;
+	u32 l;
+
+	l = omap_readl(MOD_CONF_CTRL_1) & ~(0x03 << n);
+	l |= source << n;
+	omap_writel(l, MOD_CONF_CTRL_1);
+
+	return 0;
+}
+
+static int __init omap1_dm_timer_init(void)
+{
+	int i;
+	int ret;
+	struct dmtimer_platform_data *pdata;
+	struct platform_device *pdev;
+
+	if (!cpu_is_omap16xx())
+		return 0;
+
+	for (i = 1; i <= OMAP1_DM_TIMER_COUNT; i++) {
+		struct resource res[2];
+		u32 base, irq;
+
+		switch (i) {
+		case 1:
+			base = OMAP1610_GPTIMER1_BASE;
+			irq = INT_1610_GPTIMER1;
+			break;
+		case 2:
+			base = OMAP1610_GPTIMER2_BASE;
+			irq = INT_1610_GPTIMER2;
+			break;
+		case 3:
+			base = OMAP1610_GPTIMER3_BASE;
+			irq = INT_1610_GPTIMER3;
+			break;
+		case 4:
+			base = OMAP1610_GPTIMER4_BASE;
+			irq = INT_1610_GPTIMER4;
+			break;
+		case 5:
+			base = OMAP1610_GPTIMER5_BASE;
+			irq = INT_1610_GPTIMER5;
+			break;
+		case 6:
+			base = OMAP1610_GPTIMER6_BASE;
+			irq = INT_1610_GPTIMER6;
+			break;
+		case 7:
+			base = OMAP1610_GPTIMER7_BASE;
+			irq = INT_1610_GPTIMER7;
+			break;
+		case 8:
+			base = OMAP1610_GPTIMER8_BASE;
+			irq = INT_1610_GPTIMER8;
+			break;
+		default:
+			/*
+			 * not supposed to reach here.
+			 * this is to remove warning.
+			 */
+			return -EINVAL;
+		}
+
+		pdev = platform_device_alloc("omap_timer", i);
+		if (!pdev) {
+			pr_err("%s: Failed to device alloc for dmtimer%d\n",
+				__func__, i);
+			return -ENOMEM;
+		}
+
+		memset(res, 0, 2 * sizeof(struct resource));
+		res[0].start = base;
+		res[0].end = base + 0x46;
+		res[0].flags = IORESOURCE_MEM;
+		res[1].start = irq;
+		res[1].end = irq;
+		res[1].flags = IORESOURCE_IRQ;
+		ret = platform_device_add_resources(pdev, res,
+				ARRAY_SIZE(res));
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add resources.\n",
+				__func__);
+			goto err_free_pdev;
+		}
+
+		pdata = kzalloc_obj(*pdata);
+		if (!pdata) {
+			ret = -ENOMEM;
+			goto err_free_pdata;
+		}
+
+		pdata->set_timer_src = omap1_dm_timer_set_src;
+		pdata->timer_capability = OMAP_TIMER_ALWON |
+				OMAP_TIMER_NEEDS_RESET | OMAP_TIMER_HAS_DSP_IRQ;
+
+		ret = platform_device_add_data(pdev, pdata, sizeof(*pdata));
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add platform data.\n",
+				__func__);
+			goto err_free_pdata;
+		}
+
+		ret = platform_device_add(pdev);
+		if (ret) {
+			dev_err(&pdev->dev, "%s: Failed to add platform device.\n",
+				__func__);
+			goto err_free_pdata;
+		}
+
+		dev_dbg(&pdev->dev, " Registered.\n");
+	}
+
+	return 0;
+
+err_free_pdata:
+	kfree(pdata);
+
+err_free_pdev:
+	platform_device_put(pdev);
+
+	return ret;
+}
+arch_initcall(omap1_dm_timer_init);