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, 195 insertions, 0 deletions

diff --git a/drivers/mfd/exynos-lpass.c b/drivers/mfd/exynos-lpass.c
new file mode 100644
index 000000000..9bb2687c2
--- /dev/null
+++ b/drivers/mfd/exynos-lpass.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2015 - 2016 Samsung Electronics Co., Ltd.
+ *
+ * Authors: Inha Song <ideal.song@samsung.com>
+ *          Sylwester Nawrocki <s.nawrocki@samsung.com>
+ *
+ * Samsung Exynos SoC series Low Power Audio Subsystem driver.
+ *
+ * This module provides regmap for the Top SFR region and instantiates
+ * devices for IP blocks like DMAC, I2S, UART.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/soc/samsung/exynos-regs-pmu.h>
+#include <linux/types.h>
+
+/* LPASS Top register definitions */
+#define SFR_LPASS_CORE_SW_RESET		0x08
+#define  LPASS_SB_SW_RESET		BIT(11)
+#define  LPASS_UART_SW_RESET		BIT(10)
+#define  LPASS_PCM_SW_RESET		BIT(9)
+#define  LPASS_I2S_SW_RESET		BIT(8)
+#define  LPASS_WDT1_SW_RESET		BIT(4)
+#define  LPASS_WDT0_SW_RESET		BIT(3)
+#define  LPASS_TIMER_SW_RESET		BIT(2)
+#define  LPASS_MEM_SW_RESET		BIT(1)
+#define  LPASS_DMA_SW_RESET		BIT(0)
+
+#define SFR_LPASS_INTR_CA5_MASK		0x48
+#define SFR_LPASS_INTR_CPU_MASK		0x58
+#define  LPASS_INTR_APM			BIT(9)
+#define  LPASS_INTR_MIF			BIT(8)
+#define  LPASS_INTR_TIMER		BIT(7)
+#define  LPASS_INTR_DMA			BIT(6)
+#define  LPASS_INTR_GPIO		BIT(5)
+#define  LPASS_INTR_I2S			BIT(4)
+#define  LPASS_INTR_PCM			BIT(3)
+#define  LPASS_INTR_SLIMBUS		BIT(2)
+#define  LPASS_INTR_UART		BIT(1)
+#define  LPASS_INTR_SFR			BIT(0)
+
+struct exynos_lpass {
+	/* pointer to the LPASS TOP regmap */
+	struct regmap *top;
+	struct clk *sfr0_clk;
+};
+
+static void exynos_lpass_core_sw_reset(struct exynos_lpass *lpass, int mask)
+{
+	unsigned int val = 0;
+
+	regmap_read(lpass->top, SFR_LPASS_CORE_SW_RESET, &val);
+
+	val &= ~mask;
+	regmap_write(lpass->top, SFR_LPASS_CORE_SW_RESET, val);
+
+	usleep_range(100, 150);
+
+	val |= mask;
+	regmap_write(lpass->top, SFR_LPASS_CORE_SW_RESET, val);
+}
+
+static void exynos_lpass_enable(struct exynos_lpass *lpass)
+{
+	clk_prepare_enable(lpass->sfr0_clk);
+
+	/* Unmask SFR, DMA and I2S interrupt */
+	regmap_write(lpass->top, SFR_LPASS_INTR_CA5_MASK,
+		     LPASS_INTR_SFR | LPASS_INTR_DMA | LPASS_INTR_I2S);
+
+	regmap_write(lpass->top, SFR_LPASS_INTR_CPU_MASK,
+		     LPASS_INTR_SFR | LPASS_INTR_DMA | LPASS_INTR_I2S |
+		     LPASS_INTR_UART);
+
+	exynos_lpass_core_sw_reset(lpass, LPASS_I2S_SW_RESET);
+	exynos_lpass_core_sw_reset(lpass, LPASS_DMA_SW_RESET);
+	exynos_lpass_core_sw_reset(lpass, LPASS_MEM_SW_RESET);
+	exynos_lpass_core_sw_reset(lpass, LPASS_UART_SW_RESET);
+}
+
+static void exynos_lpass_disable(struct exynos_lpass *lpass)
+{
+	/* Mask any unmasked IP interrupt sources */
+	regmap_write(lpass->top, SFR_LPASS_INTR_CPU_MASK, 0);
+	regmap_write(lpass->top, SFR_LPASS_INTR_CA5_MASK, 0);
+
+	clk_disable_unprepare(lpass->sfr0_clk);
+}
+
+static const struct regmap_config exynos_lpass_reg_conf = {
+	.reg_bits	= 32,
+	.reg_stride	= 4,
+	.val_bits	= 32,
+	.max_register	= 0xfc,
+};
+
+static void exynos_lpass_disable_lpass(void *data)
+{
+	struct platform_device *pdev = data;
+	struct exynos_lpass *lpass = platform_get_drvdata(pdev);
+
+	pm_runtime_disable(&pdev->dev);
+	if (!pm_runtime_status_suspended(&pdev->dev))
+		exynos_lpass_disable(lpass);
+}
+
+static int exynos_lpass_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct exynos_lpass *lpass;
+	void __iomem *base_top;
+	int ret;
+
+	lpass = devm_kzalloc(dev, sizeof(*lpass), GFP_KERNEL);
+	if (!lpass)
+		return -ENOMEM;
+
+	base_top = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base_top))
+		return PTR_ERR(base_top);
+
+	lpass->sfr0_clk = devm_clk_get(dev, "sfr0_ctrl");
+	if (IS_ERR(lpass->sfr0_clk))
+		return PTR_ERR(lpass->sfr0_clk);
+
+	lpass->top = devm_regmap_init_mmio(dev, base_top,
+					   &exynos_lpass_reg_conf);
+	if (IS_ERR(lpass->top)) {
+		dev_err(dev, "LPASS top regmap initialization failed\n");
+		return PTR_ERR(lpass->top);
+	}
+
+	platform_set_drvdata(pdev, lpass);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	exynos_lpass_enable(lpass);
+
+	ret = devm_add_action_or_reset(dev, exynos_lpass_disable_lpass, pdev);
+	if (ret)
+		return ret;
+
+	return devm_of_platform_populate(dev);
+}
+
+static int __maybe_unused exynos_lpass_suspend(struct device *dev)
+{
+	struct exynos_lpass *lpass = dev_get_drvdata(dev);
+
+	exynos_lpass_disable(lpass);
+
+	return 0;
+}
+
+static int __maybe_unused exynos_lpass_resume(struct device *dev)
+{
+	struct exynos_lpass *lpass = dev_get_drvdata(dev);
+
+	exynos_lpass_enable(lpass);
+
+	return 0;
+}
+
+static const struct dev_pm_ops lpass_pm_ops = {
+	SET_RUNTIME_PM_OPS(exynos_lpass_suspend, exynos_lpass_resume, NULL)
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				     pm_runtime_force_resume)
+};
+
+static const struct of_device_id exynos_lpass_of_match[] = {
+	{ .compatible = "samsung,exynos5433-lpass" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, exynos_lpass_of_match);
+
+static struct platform_driver exynos_lpass_driver = {
+	.driver	= {
+		.name		= "exynos-lpass",
+		.pm		= &lpass_pm_ops,
+		.of_match_table	= exynos_lpass_of_match,
+	},
+	.probe	= exynos_lpass_probe,
+};
+module_platform_driver(exynos_lpass_driver);
+
+MODULE_DESCRIPTION("Samsung Low Power Audio Subsystem driver");
+MODULE_LICENSE("GPL v2");