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, 448 insertions, 0 deletions

diff --git a/drivers/clk/qcom/krait-cc.c b/drivers/clk/qcom/krait-cc.c
new file mode 100644
index 000000000..f29d6dd1f
--- /dev/null
+++ b/drivers/clk/qcom/krait-cc.c
@@ -0,0 +1,448 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+
+#include "clk-krait.h"
+
+enum {
+	cpu0_mux = 0,
+	cpu1_mux,
+	cpu2_mux,
+	cpu3_mux,
+	l2_mux,
+
+	clks_max,
+};
+
+static unsigned int sec_mux_map[] = {
+	2,
+	0,
+};
+
+static unsigned int pri_mux_map[] = {
+	1,
+	2,
+	0,
+};
+
+/*
+ * Notifier function for switching the muxes to safe parent
+ * while the hfpll is getting reprogrammed.
+ */
+static int krait_notifier_cb(struct notifier_block *nb,
+			     unsigned long event,
+			     void *data)
+{
+	int ret = 0;
+	struct krait_mux_clk *mux = container_of(nb, struct krait_mux_clk,
+						 clk_nb);
+	/* Switch to safe parent */
+	if (event == PRE_RATE_CHANGE) {
+		mux->old_index = krait_mux_clk_ops.get_parent(&mux->hw);
+		ret = krait_mux_clk_ops.set_parent(&mux->hw, mux->safe_sel);
+		mux->reparent = false;
+	/*
+	 * By the time POST_RATE_CHANGE notifier is called,
+	 * clk framework itself would have changed the parent for the new rate.
+	 * Only otherwise, put back to the old parent.
+	 */
+	} else if (event == POST_RATE_CHANGE) {
+		if (!mux->reparent)
+			ret = krait_mux_clk_ops.set_parent(&mux->hw,
+							   mux->old_index);
+	}
+
+	return notifier_from_errno(ret);
+}
+
+static int krait_notifier_register(struct device *dev, struct clk *clk,
+				   struct krait_mux_clk *mux)
+{
+	int ret = 0;
+
+	mux->clk_nb.notifier_call = krait_notifier_cb;
+	ret = devm_clk_notifier_register(dev, clk, &mux->clk_nb);
+	if (ret)
+		dev_err(dev, "failed to register clock notifier: %d\n", ret);
+
+	return ret;
+}
+
+static struct clk_hw *
+krait_add_div(struct device *dev, int id, const char *s, unsigned int offset)
+{
+	struct krait_div2_clk *div;
+	static struct clk_parent_data p_data[1];
+	struct clk_init_data init = {
+		.num_parents = ARRAY_SIZE(p_data),
+		.ops = &krait_div2_clk_ops,
+		.flags = CLK_SET_RATE_PARENT,
+	};
+	struct clk_hw *clk;
+	char *parent_name;
+	int cpu, ret;
+
+	div = devm_kzalloc(dev, sizeof(*div), GFP_KERNEL);
+	if (!div)
+		return ERR_PTR(-ENOMEM);
+
+	div->width = 2;
+	div->shift = 6;
+	div->lpl = id >= 0;
+	div->offset = offset;
+	div->hw.init = &init;
+
+	init.name = kasprintf(GFP_KERNEL, "hfpll%s_div", s);
+	if (!init.name)
+		return ERR_PTR(-ENOMEM);
+
+	init.parent_data = p_data;
+	parent_name = kasprintf(GFP_KERNEL, "hfpll%s", s);
+	if (!parent_name) {
+		clk = ERR_PTR(-ENOMEM);
+		goto err_parent_name;
+	}
+
+	p_data[0].fw_name = parent_name;
+	p_data[0].name = parent_name;
+
+	ret = devm_clk_hw_register(dev, &div->hw);
+	if (ret) {
+		clk = ERR_PTR(ret);
+		goto err_clk;
+	}
+
+	clk = &div->hw;
+
+	/* clk-krait ignore any rate change if mux is not flagged as enabled */
+	if (id < 0)
+		for_each_online_cpu(cpu)
+			clk_prepare_enable(div->hw.clk);
+	else
+		clk_prepare_enable(div->hw.clk);
+
+err_clk:
+	kfree(parent_name);
+err_parent_name:
+	kfree(init.name);
+
+	return clk;
+}
+
+static struct clk_hw *
+krait_add_sec_mux(struct device *dev, int id, const char *s,
+		  unsigned int offset, bool unique_aux)
+{
+	int cpu, ret;
+	struct krait_mux_clk *mux;
+	static struct clk_parent_data sec_mux_list[2] = {
+		{ .name = "qsb", .fw_name = "qsb" },
+		{},
+	};
+	struct clk_init_data init = {
+		.parent_data = sec_mux_list,
+		.num_parents = ARRAY_SIZE(sec_mux_list),
+		.ops = &krait_mux_clk_ops,
+		.flags = CLK_SET_RATE_PARENT,
+	};
+	struct clk_hw *clk;
+	char *parent_name;
+
+	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return ERR_PTR(-ENOMEM);
+
+	mux->offset = offset;
+	mux->lpl = id >= 0;
+	mux->mask = 0x3;
+	mux->shift = 2;
+	mux->parent_map = sec_mux_map;
+	mux->hw.init = &init;
+	mux->safe_sel = 0;
+
+	/* Checking for qcom,krait-cc-v1 or qcom,krait-cc-v2 is not
+	 * enough to limit this to apq/ipq8064. Directly check machine
+	 * compatible to correctly handle this errata.
+	 */
+	if (of_machine_is_compatible("qcom,ipq8064") ||
+	    of_machine_is_compatible("qcom,apq8064"))
+		mux->disable_sec_src_gating = true;
+
+	init.name = kasprintf(GFP_KERNEL, "krait%s_sec_mux", s);
+	if (!init.name)
+		return ERR_PTR(-ENOMEM);
+
+	if (unique_aux) {
+		parent_name = kasprintf(GFP_KERNEL, "acpu%s_aux", s);
+		if (!parent_name) {
+			clk = ERR_PTR(-ENOMEM);
+			goto err_aux;
+		}
+		sec_mux_list[1].fw_name = parent_name;
+		sec_mux_list[1].name = parent_name;
+	} else {
+		sec_mux_list[1].name = "apu_aux";
+	}
+
+	ret = devm_clk_hw_register(dev, &mux->hw);
+	if (ret) {
+		clk = ERR_PTR(ret);
+		goto err_clk;
+	}
+
+	clk = &mux->hw;
+
+	ret = krait_notifier_register(dev, mux->hw.clk, mux);
+	if (ret) {
+		clk = ERR_PTR(ret);
+		goto err_clk;
+	}
+
+	/* clk-krait ignore any rate change if mux is not flagged as enabled */
+	if (id < 0)
+		for_each_online_cpu(cpu)
+			clk_prepare_enable(mux->hw.clk);
+	else
+		clk_prepare_enable(mux->hw.clk);
+
+err_clk:
+	if (unique_aux)
+		kfree(parent_name);
+err_aux:
+	kfree(init.name);
+	return clk;
+}
+
+static struct clk_hw *
+krait_add_pri_mux(struct device *dev, struct clk_hw *hfpll_div, struct clk_hw *sec_mux,
+		  int id, const char *s, unsigned int offset)
+{
+	int ret;
+	struct krait_mux_clk *mux;
+	static struct clk_parent_data p_data[3];
+	struct clk_init_data init = {
+		.parent_data = p_data,
+		.num_parents = ARRAY_SIZE(p_data),
+		.ops = &krait_mux_clk_ops,
+		.flags = CLK_SET_RATE_PARENT,
+	};
+	struct clk_hw *clk;
+	char *hfpll_name;
+
+	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
+	if (!mux)
+		return ERR_PTR(-ENOMEM);
+
+	mux->mask = 0x3;
+	mux->shift = 0;
+	mux->offset = offset;
+	mux->lpl = id >= 0;
+	mux->parent_map = pri_mux_map;
+	mux->hw.init = &init;
+	mux->safe_sel = 2;
+
+	init.name = kasprintf(GFP_KERNEL, "krait%s_pri_mux", s);
+	if (!init.name)
+		return ERR_PTR(-ENOMEM);
+
+	hfpll_name = kasprintf(GFP_KERNEL, "hfpll%s", s);
+	if (!hfpll_name) {
+		clk = ERR_PTR(-ENOMEM);
+		goto err_hfpll;
+	}
+
+	p_data[0].fw_name = hfpll_name;
+	p_data[0].name = hfpll_name;
+
+	p_data[1].hw = hfpll_div;
+	p_data[2].hw = sec_mux;
+
+	ret = devm_clk_hw_register(dev, &mux->hw);
+	if (ret) {
+		clk = ERR_PTR(ret);
+		goto err_clk;
+	}
+
+	clk = &mux->hw;
+
+	ret = krait_notifier_register(dev, mux->hw.clk, mux);
+	if (ret)
+		clk = ERR_PTR(ret);
+
+err_clk:
+	kfree(hfpll_name);
+err_hfpll:
+	kfree(init.name);
+	return clk;
+}
+
+/* id < 0 for L2, otherwise id == physical CPU number */
+static struct clk_hw *krait_add_clks(struct device *dev, int id, bool unique_aux)
+{
+	struct clk_hw *hfpll_div, *sec_mux, *pri_mux;
+	unsigned int offset;
+	void *p = NULL;
+	const char *s;
+
+	if (id >= 0) {
+		offset = 0x4501 + (0x1000 * id);
+		s = p = kasprintf(GFP_KERNEL, "%d", id);
+		if (!s)
+			return ERR_PTR(-ENOMEM);
+	} else {
+		offset = 0x500;
+		s = "_l2";
+	}
+
+	hfpll_div = krait_add_div(dev, id, s, offset);
+	if (IS_ERR(hfpll_div)) {
+		pri_mux = hfpll_div;
+		goto err;
+	}
+
+	sec_mux = krait_add_sec_mux(dev, id, s, offset, unique_aux);
+	if (IS_ERR(sec_mux)) {
+		pri_mux = sec_mux;
+		goto err;
+	}
+
+	pri_mux = krait_add_pri_mux(dev, hfpll_div, sec_mux, id, s, offset);
+
+err:
+	kfree(p);
+	return pri_mux;
+}
+
+static struct clk *krait_of_get(struct of_phandle_args *clkspec, void *data)
+{
+	unsigned int idx = clkspec->args[0];
+	struct clk **clks = data;
+
+	if (idx >= clks_max) {
+		pr_err("%s: invalid clock index %d\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return clks[idx] ? : ERR_PTR(-ENODEV);
+}
+
+static const struct of_device_id krait_cc_match_table[] = {
+	{ .compatible = "qcom,krait-cc-v1", (void *)1UL },
+	{ .compatible = "qcom,krait-cc-v2" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, krait_cc_match_table);
+
+static int krait_cc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	unsigned long cur_rate, aux_rate;
+	int cpu;
+	struct clk_hw *mux, *l2_pri_mux;
+	struct clk *clk, **clks;
+	bool unique_aux = !!device_get_match_data(dev);
+
+	/* Rate is 1 because 0 causes problems for __clk_mux_determine_rate */
+	clk = clk_register_fixed_rate(dev, "qsb", NULL, 0, 1);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	if (!unique_aux) {
+		clk = clk_register_fixed_factor(dev, "acpu_aux",
+						"gpll0_vote", 0, 1, 2);
+		if (IS_ERR(clk))
+			return PTR_ERR(clk);
+	}
+
+	/* Krait configurations have at most 4 CPUs and one L2 */
+	clks = devm_kcalloc(dev, clks_max, sizeof(*clks), GFP_KERNEL);
+	if (!clks)
+		return -ENOMEM;
+
+	for_each_possible_cpu(cpu) {
+		mux = krait_add_clks(dev, cpu, unique_aux);
+		if (IS_ERR(mux))
+			return PTR_ERR(mux);
+		clks[cpu] = mux->clk;
+	}
+
+	l2_pri_mux = krait_add_clks(dev, -1, unique_aux);
+	if (IS_ERR(l2_pri_mux))
+		return PTR_ERR(l2_pri_mux);
+	clks[l2_mux] = l2_pri_mux->clk;
+
+	/*
+	 * We don't want the CPU or L2 clocks to be turned off at late init
+	 * if CPUFREQ or HOTPLUG configs are disabled. So, bump up the
+	 * refcount of these clocks. Any cpufreq/hotplug manager can assume
+	 * that the clocks have already been prepared and enabled by the time
+	 * they take over.
+	 */
+	for_each_online_cpu(cpu) {
+		clk_prepare_enable(clks[l2_mux]);
+		WARN(clk_prepare_enable(clks[cpu]),
+		     "Unable to turn on CPU%d clock", cpu);
+	}
+
+	/*
+	 * Force reinit of HFPLLs and muxes to overwrite any potential
+	 * incorrect configuration of HFPLLs and muxes by the bootloader.
+	 * While at it, also make sure the cores are running at known rates
+	 * and print the current rate.
+	 *
+	 * The clocks are set to aux clock rate first to make sure the
+	 * secondary mux is not sourcing off of QSB. The rate is then set to
+	 * two different rates to force a HFPLL reinit under all
+	 * circumstances.
+	 */
+	cur_rate = clk_get_rate(clks[l2_mux]);
+	aux_rate = 384000000;
+	if (cur_rate < aux_rate) {
+		pr_info("L2 @ Undefined rate. Forcing new rate.\n");
+		cur_rate = aux_rate;
+	}
+	clk_set_rate(clks[l2_mux], aux_rate);
+	clk_set_rate(clks[l2_mux], 2);
+	clk_set_rate(clks[l2_mux], cur_rate);
+	pr_info("L2 @ %lu KHz\n", clk_get_rate(clks[l2_mux]) / 1000);
+	for_each_possible_cpu(cpu) {
+		clk = clks[cpu];
+		cur_rate = clk_get_rate(clk);
+		if (cur_rate < aux_rate) {
+			pr_info("CPU%d @ Undefined rate. Forcing new rate.\n", cpu);
+			cur_rate = aux_rate;
+		}
+
+		clk_set_rate(clk, aux_rate);
+		clk_set_rate(clk, 2);
+		clk_set_rate(clk, cur_rate);
+		pr_info("CPU%d @ %lu KHz\n", cpu, clk_get_rate(clk) / 1000);
+	}
+
+	of_clk_add_provider(dev->of_node, krait_of_get, clks);
+
+	return 0;
+}
+
+static struct platform_driver krait_cc_driver = {
+	.probe = krait_cc_probe,
+	.driver = {
+		.name = "krait-cc",
+		.of_match_table = krait_cc_match_table,
+	},
+};
+module_platform_driver(krait_cc_driver);
+
+MODULE_DESCRIPTION("Krait CPU Clock Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:krait-cc");