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, 168 insertions, 0 deletions

diff --git a/drivers/spmi/spmi-apple-controller.c b/drivers/spmi/spmi-apple-controller.c
new file mode 100644
index 000000000..376cf682c
--- /dev/null
+++ b/drivers/spmi/spmi-apple-controller.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Apple SoC SPMI device driver
+ *
+ * Copyright The Asahi Linux Contributors
+ *
+ * Inspired by:
+ *		OpenBSD support Copyright (c) 2021 Mark Kettenis <kettenis@openbsd.org>
+ *		Correllium support Copyright (C) 2021 Corellium LLC
+ *		hisi-spmi-controller.c
+ *		spmi-pmic-arb.c Copyright (c) 2021, The Linux Foundation.
+ */
+
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spmi.h>
+
+/* SPMI Controller Registers */
+#define SPMI_STATUS_REG 0
+#define SPMI_CMD_REG 0x4
+#define SPMI_RSP_REG 0x8
+
+#define SPMI_RX_FIFO_EMPTY BIT(24)
+
+#define REG_POLL_INTERVAL_US 10000
+#define REG_POLL_TIMEOUT_US (REG_POLL_INTERVAL_US * 5)
+
+struct apple_spmi {
+	void __iomem *regs;
+};
+
+#define poll_reg(spmi, reg, val, cond) \
+	readl_poll_timeout((spmi)->regs + (reg), (val), (cond), \
+			   REG_POLL_INTERVAL_US, REG_POLL_TIMEOUT_US)
+
+static inline u32 apple_spmi_pack_cmd(u8 opc, u8 sid, u16 saddr, size_t len)
+{
+	return opc | sid << 8 | saddr << 16 | (len - 1) | (1 << 15);
+}
+
+/* Wait for Rx FIFO to have something */
+static int apple_spmi_wait_rx_not_empty(struct spmi_controller *ctrl)
+{
+	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
+	int ret;
+	u32 status;
+
+	ret = poll_reg(spmi, SPMI_STATUS_REG, status, !(status & SPMI_RX_FIFO_EMPTY));
+	if (ret) {
+		dev_err(&ctrl->dev,
+			"failed to wait for RX FIFO not empty\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int spmi_read_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
+			 u16 saddr, u8 *buf, size_t len)
+{
+	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
+	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
+	u32 rsp;
+	size_t len_read = 0;
+	u8 i;
+	int ret;
+
+	writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
+
+	ret = apple_spmi_wait_rx_not_empty(ctrl);
+	if (ret)
+		return ret;
+
+	/* Discard SPMI reply status */
+	readl(spmi->regs + SPMI_RSP_REG);
+
+	/* Read SPMI data reply */
+	while (len_read < len) {
+		rsp = readl(spmi->regs + SPMI_RSP_REG);
+		i = 0;
+		while ((len_read < len) && (i < 4)) {
+			buf[len_read++] = ((0xff << (8 * i)) & rsp) >> (8 * i);
+			i += 1;
+		}
+	}
+
+	return 0;
+}
+
+static int spmi_write_cmd(struct spmi_controller *ctrl, u8 opc, u8 sid,
+			  u16 saddr, const u8 *buf, size_t len)
+{
+	struct apple_spmi *spmi = spmi_controller_get_drvdata(ctrl);
+	u32 spmi_cmd = apple_spmi_pack_cmd(opc, sid, saddr, len);
+	size_t i = 0, j;
+	int ret;
+
+	writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
+
+	while (i < len) {
+		j = 0;
+		spmi_cmd = 0;
+		while ((j < 4) & (i < len))
+			spmi_cmd |= buf[i++] << (j++ * 8);
+
+		writel(spmi_cmd, spmi->regs + SPMI_CMD_REG);
+	}
+
+	ret = apple_spmi_wait_rx_not_empty(ctrl);
+	if (ret)
+		return ret;
+
+	/* Discard */
+	readl(spmi->regs + SPMI_RSP_REG);
+
+	return 0;
+}
+
+static int apple_spmi_probe(struct platform_device *pdev)
+{
+	struct apple_spmi *spmi;
+	struct spmi_controller *ctrl;
+	int ret;
+
+	ctrl = devm_spmi_controller_alloc(&pdev->dev, sizeof(*spmi));
+	if (IS_ERR(ctrl))
+		return -ENOMEM;
+
+	spmi = spmi_controller_get_drvdata(ctrl);
+
+	spmi->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(spmi->regs))
+		return PTR_ERR(spmi->regs);
+
+	ctrl->dev.of_node = pdev->dev.of_node;
+
+	ctrl->read_cmd = spmi_read_cmd;
+	ctrl->write_cmd = spmi_write_cmd;
+
+	ret = devm_spmi_controller_add(&pdev->dev, ctrl);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret,
+				     "spmi_controller_add failed\n");
+
+	return 0;
+}
+
+static const struct of_device_id apple_spmi_match_table[] = {
+	{ .compatible = "apple,t8103-spmi", },
+	{ .compatible = "apple,spmi", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, apple_spmi_match_table);
+
+static struct platform_driver apple_spmi_driver = {
+	.probe		= apple_spmi_probe,
+	.driver		= {
+		.name	= "apple-spmi",
+		.of_match_table = apple_spmi_match_table,
+	},
+};
+module_platform_driver(apple_spmi_driver);
+
+MODULE_AUTHOR("Jean-Francois Bortolotti <jeff@borto.fr>");
+MODULE_DESCRIPTION("Apple SoC SPMI driver");
+MODULE_LICENSE("GPL");