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, 370 insertions, 0 deletions

diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
new file mode 100644
index 000000000..ea994647a
--- /dev/null
+++ b/drivers/cpufreq/freq_table.c
@@ -0,0 +1,370 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/cpufreq/freq_table.c
+ *
+ * Copyright (C) 2002 - 2003 Dominik Brodowski
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufreq.h>
+#include <linux/module.h>
+
+/*********************************************************************
+ *                     FREQUENCY TABLE HELPERS                       *
+ *********************************************************************/
+
+static bool policy_has_boost_freq(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+
+	if (!table)
+		return false;
+
+	cpufreq_for_each_valid_entry(pos, table)
+		if (pos->flags & CPUFREQ_BOOST_FREQ)
+			return true;
+
+	return false;
+}
+
+int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+	unsigned int min_freq = ~0;
+	unsigned int max_freq = 0;
+	unsigned int freq, i;
+
+	cpufreq_for_each_valid_entry_idx(pos, table, i) {
+		freq = pos->frequency;
+
+		if ((!cpufreq_boost_enabled() || !policy->boost_enabled)
+		    && (pos->flags & CPUFREQ_BOOST_FREQ))
+			continue;
+
+		pr_debug("table entry %u: %u kHz\n", i, freq);
+		if (freq < min_freq)
+			min_freq = freq;
+		if (freq > max_freq)
+			max_freq = freq;
+	}
+
+	policy->cpuinfo.min_freq = min_freq;
+	/*
+	 * If the driver has set its own cpuinfo.max_freq above max_freq, leave
+	 * it as is.
+	 */
+	if (policy->cpuinfo.max_freq < max_freq)
+		policy->cpuinfo.max_freq = max_freq;
+
+	if (min_freq == ~0)
+		return -EINVAL;
+	else
+		return 0;
+}
+
+int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+	unsigned int freq, prev_smaller = 0;
+	bool found = false;
+
+	pr_debug("request for verification of policy (%u - %u kHz) for cpu %u\n",
+					policy->min, policy->max, policy->cpu);
+
+	cpufreq_verify_within_cpu_limits(policy);
+
+	cpufreq_for_each_valid_entry(pos, table) {
+		freq = pos->frequency;
+
+		if ((freq >= policy->min) && (freq <= policy->max)) {
+			found = true;
+			break;
+		}
+
+		if ((prev_smaller < freq) && (freq <= policy->max))
+			prev_smaller = freq;
+	}
+
+	if (!found) {
+		policy->max = prev_smaller;
+		cpufreq_verify_within_cpu_limits(policy);
+	}
+
+	pr_debug("verification lead to (%u - %u kHz) for cpu %u\n",
+				policy->min, policy->max, policy->cpu);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_verify);
+
+/*
+ * Generic routine to verify policy & frequency table, requires driver to set
+ * policy->freq_table prior to it.
+ */
+int cpufreq_generic_frequency_table_verify(struct cpufreq_policy_data *policy)
+{
+	if (!policy->freq_table)
+		return -ENODEV;
+
+	return cpufreq_frequency_table_verify(policy);
+}
+EXPORT_SYMBOL_GPL(cpufreq_generic_frequency_table_verify);
+
+int cpufreq_table_index_unsorted(struct cpufreq_policy *policy,
+				 unsigned int target_freq, unsigned int min,
+				 unsigned int max, unsigned int relation)
+{
+	struct cpufreq_frequency_table optimal = {
+		.driver_data = ~0,
+		.frequency = 0,
+	};
+	struct cpufreq_frequency_table suboptimal = {
+		.driver_data = ~0,
+		.frequency = 0,
+	};
+	struct cpufreq_frequency_table *pos;
+	struct cpufreq_frequency_table *table = policy->freq_table;
+	unsigned int freq, diff, i;
+	int index;
+
+	pr_debug("request for target %u kHz (relation: %u) for cpu %u\n",
+					target_freq, relation, policy->cpu);
+
+	switch (relation) {
+	case CPUFREQ_RELATION_H:
+		suboptimal.frequency = ~0;
+		break;
+	case CPUFREQ_RELATION_L:
+	case CPUFREQ_RELATION_C:
+		optimal.frequency = ~0;
+		break;
+	}
+
+	cpufreq_for_each_valid_entry_idx(pos, table, i) {
+		freq = pos->frequency;
+
+		if (freq < min || freq > max)
+			continue;
+		if (freq == target_freq) {
+			optimal.driver_data = i;
+			break;
+		}
+		switch (relation) {
+		case CPUFREQ_RELATION_H:
+			if (freq < target_freq) {
+				if (freq >= optimal.frequency) {
+					optimal.frequency = freq;
+					optimal.driver_data = i;
+				}
+			} else {
+				if (freq <= suboptimal.frequency) {
+					suboptimal.frequency = freq;
+					suboptimal.driver_data = i;
+				}
+			}
+			break;
+		case CPUFREQ_RELATION_L:
+			if (freq > target_freq) {
+				if (freq <= optimal.frequency) {
+					optimal.frequency = freq;
+					optimal.driver_data = i;
+				}
+			} else {
+				if (freq >= suboptimal.frequency) {
+					suboptimal.frequency = freq;
+					suboptimal.driver_data = i;
+				}
+			}
+			break;
+		case CPUFREQ_RELATION_C:
+			diff = abs(freq - target_freq);
+			if (diff < optimal.frequency ||
+			    (diff == optimal.frequency &&
+			     freq > table[optimal.driver_data].frequency)) {
+				optimal.frequency = diff;
+				optimal.driver_data = i;
+			}
+			break;
+		}
+	}
+	if (optimal.driver_data > i) {
+		if (suboptimal.driver_data > i) {
+			WARN(1, "Invalid frequency table: %u\n", policy->cpu);
+			return 0;
+		}
+
+		index = suboptimal.driver_data;
+	} else
+		index = optimal.driver_data;
+
+	pr_debug("target index is %u, freq is:%u kHz\n", index,
+		 table[index].frequency);
+	return index;
+}
+EXPORT_SYMBOL_GPL(cpufreq_table_index_unsorted);
+
+int cpufreq_frequency_table_get_index(struct cpufreq_policy *policy,
+		unsigned int freq)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+	int idx;
+
+	if (unlikely(!table)) {
+		pr_debug("%s: Unable to find frequency table\n", __func__);
+		return -ENOENT;
+	}
+
+	cpufreq_for_each_valid_entry_idx(pos, table, idx)
+		if (pos->frequency == freq)
+			return idx;
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_get_index);
+
+/*
+ * show_available_freqs - show available frequencies for the specified CPU
+ */
+static ssize_t show_available_freqs(struct cpufreq_policy *policy, char *buf,
+				    bool show_boost)
+{
+	ssize_t count = 0;
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+
+	if (!table)
+		return -ENODEV;
+
+	cpufreq_for_each_valid_entry(pos, table) {
+		/*
+		 * show_boost = true and driver_data = BOOST freq
+		 * display BOOST freqs
+		 *
+		 * show_boost = false and driver_data = BOOST freq
+		 * show_boost = true and driver_data != BOOST freq
+		 * continue - do not display anything
+		 *
+		 * show_boost = false and driver_data != BOOST freq
+		 * display NON BOOST freqs
+		 */
+		if (show_boost ^ (pos->flags & CPUFREQ_BOOST_FREQ))
+			continue;
+
+		count += sprintf(&buf[count], "%u ", pos->frequency);
+	}
+	count += sprintf(&buf[count], "\n");
+
+	return count;
+
+}
+
+#define cpufreq_attr_available_freq(_name)	  \
+struct freq_attr cpufreq_freq_attr_##_name##_freqs =     \
+__ATTR_RO(_name##_frequencies)
+
+/*
+ * scaling_available_frequencies_show - show available normal frequencies for
+ * the specified CPU
+ */
+static ssize_t scaling_available_frequencies_show(struct cpufreq_policy *policy,
+						  char *buf)
+{
+	return show_available_freqs(policy, buf, false);
+}
+cpufreq_attr_available_freq(scaling_available);
+
+/*
+ * scaling_boost_frequencies_show - show available boost frequencies for
+ * the specified CPU
+ */
+static ssize_t scaling_boost_frequencies_show(struct cpufreq_policy *policy,
+					      char *buf)
+{
+	return show_available_freqs(policy, buf, true);
+}
+cpufreq_attr_available_freq(scaling_boost);
+
+static int set_freq_table_sorted(struct cpufreq_policy *policy)
+{
+	struct cpufreq_frequency_table *pos, *table = policy->freq_table;
+	struct cpufreq_frequency_table *prev = NULL;
+	int ascending = 0;
+
+	policy->freq_table_sorted = CPUFREQ_TABLE_UNSORTED;
+
+	cpufreq_for_each_valid_entry(pos, table) {
+		if (!prev) {
+			prev = pos;
+			continue;
+		}
+
+		if (pos->frequency == prev->frequency) {
+			pr_warn("Duplicate freq-table entries: %u\n",
+				pos->frequency);
+			return -EINVAL;
+		}
+
+		/* Frequency increased from prev to pos */
+		if (pos->frequency > prev->frequency) {
+			/* But frequency was decreasing earlier */
+			if (ascending < 0) {
+				pr_debug("Freq table is unsorted\n");
+				return 0;
+			}
+
+			ascending++;
+		} else {
+			/* Frequency decreased from prev to pos */
+
+			/* But frequency was increasing earlier */
+			if (ascending > 0) {
+				pr_debug("Freq table is unsorted\n");
+				return 0;
+			}
+
+			ascending--;
+		}
+
+		prev = pos;
+	}
+
+	if (ascending > 0)
+		policy->freq_table_sorted = CPUFREQ_TABLE_SORTED_ASCENDING;
+	else
+		policy->freq_table_sorted = CPUFREQ_TABLE_SORTED_DESCENDING;
+
+	pr_debug("Freq table is sorted in %s order\n",
+		 ascending > 0 ? "ascending" : "descending");
+
+	return 0;
+}
+
+int cpufreq_table_validate_and_sort(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (!policy->freq_table) {
+		/* Freq table must be passed by drivers with target_index() */
+		if (has_target_index())
+			return -EINVAL;
+
+		return 0;
+	}
+
+	ret = cpufreq_frequency_table_cpuinfo(policy);
+	if (ret)
+		return ret;
+
+	/* Driver's may have set this field already */
+	if (policy_has_boost_freq(policy))
+		policy->boost_supported = true;
+
+	if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING ||
+	    policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_DESCENDING)
+		return 0;
+
+	return set_freq_table_sorted(policy);
+}
+
+MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
+MODULE_DESCRIPTION("CPUfreq frequency table helpers");