linux-brain/kernel/irq/proc.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
 *
 * This file contains the /proc/irq/ handling code.
 */

#include <linux/irq.h>
#include <linux/gfp.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/mutex.h>

#include "internals.h"

/*
 * Access rules:
 *
 * procfs protects read/write of /proc/irq/N/ files against a
 * concurrent free of the interrupt descriptor. remove_proc_entry()
 * immediately prevents new read/writes to happen and waits for
 * already running read/write functions to complete.
 *
 * We remove the proc entries first and then delete the interrupt
 * descriptor from the radix tree and free it. So it is guaranteed
 * that irq_to_desc(N) is valid as long as the read/writes are
 * permitted by procfs.
 *
 * The read from /proc/interrupts is a different problem because there
 * is no protection. So the lookup and the access to irqdesc
 * information must be protected by sparse_irq_lock.
 */
static struct proc_dir_entry *root_irq_dir;

#ifdef CONFIG_SMP

enum {
	AFFINITY,
	AFFINITY_LIST,
	EFFECTIVE,
	EFFECTIVE_LIST,
};

static int show_irq_affinity(int type, struct seq_file *m)
{
	struct irq_desc *desc = irq_to_desc((long)m->private);
	const struct cpumask *mask;

	switch (type) {
	case AFFINITY:
	case AFFINITY_LIST:
		mask = desc->irq_common_data.affinity;
#ifdef CONFIG_GENERIC_PENDING_IRQ
		if (irqd_is_setaffinity_pending(&desc->irq_data))
			mask = desc->pending_mask;
#endif
		break;
	case EFFECTIVE:
	case EFFECTIVE_LIST:
#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
		mask = irq_data_get_effective_affinity_mask(&desc->irq_data);
		break;
#endif
	default:
		return -EINVAL;
	}

	switch (type) {
	case AFFINITY_LIST:
	case EFFECTIVE_LIST:
		seq_printf(m, "%*pbl\n", cpumask_pr_args(mask));
		break;
	case AFFINITY:
	case EFFECTIVE:
		seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
		break;
	}
	return 0;
}

static int irq_affinity_hint_proc_show(struct seq_file *m, void *v)
{
	struct irq_desc *desc = irq_to_desc((long)m->private);
	unsigned long flags;
	cpumask_var_t mask;

	if (!zalloc_cpumask_var(&mask, GFP_KERNEL))
		return -ENOMEM;

	raw_spin_lock_irqsave(&desc->lock, flags);
	if (desc->affinity_hint)
		cpumask_copy(mask, desc->affinity_hint);
	raw_spin_unlock_irqrestore(&desc->lock, flags);

	seq_printf(m, "%*pb\n", cpumask_pr_args(mask));
	free_cpumask_var(mask);

	return 0;
}

int no_irq_affinity;
static int irq_affinity_proc_show(struct seq_file *m, void *v)
{
	return show_irq_affinity(AFFINITY, m);
}

static int irq_affinity_list_proc_show(struct seq_file *m, void *v)
{
	return show_irq_affinity(AFFINITY_LIST, m);
}

#ifndef CONFIG_AUTO_IRQ_AFFINITY
static inline int irq_select_affinity_usr(unsigned int irq)
{
	/*
	 * If the interrupt is started up already then this fails. The
	 * interrupt is assigned to an online CPU already. There is no
	 * point to move it around randomly. Tell user space that the
	 * selected mask is bogus.
	 *
	 * If not then any change to the affinity is pointless because the
	 * startup code invokes irq_setup_affinity() which will select
	 * a online CPU anyway.
	 */
	return -EINVAL;
}
#else
/* ALPHA magic affinity auto selector. Keep it for historical reasons. */
static inline int irq_select_affinity_usr(unsigned int irq)
{
	return irq_select_affinity(irq);
}
#endif

static ssize_t write_irq_affinity(int type, struct file *file,
		const char __user *buffer, size_t count, loff_t *pos)
{
	unsigned int irq = (int)(long)PDE_DATA(file_inode(file));
	cpumask_var_t new_value;
	int err;

	if (!irq_can_set_affinity_usr(irq) || no_irq_affinity)
		return -EIO;

	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
		return -ENOMEM;

	if (type)
		err = cpumask_parselist_user(buffer, count, new_value);
	else
		err = cpumask_parse_user(buffer, count, new_value);
	if (err)
		goto free_cpumask;

	/*
	 * Do not allow disabling IRQs completely - it's a too easy
	 * way to make the system unusable accidentally :-) At least
	 * one online CPU still has to be targeted.
	 */
	if (!cpumask_intersects(new_value, cpu_online_mask)) {
		/*
		 * Special case for empty set - allow the architecture code
		 * to set default SMP affinity.
		 */
		err = irq_select_affinity_usr(irq) ? -EINVAL : count;
	} else {
		err = irq_set_affinity(irq, new_value);
		if (!err)
			err = count;
	}

free_cpumask:
	free_cpumask_var(new_value);
	return err;
}

static ssize_t irq_affinity_proc_write(struct file *file,
		const char __user *buffer, size_t count, loff_t *pos)
{
	return write_irq_affinity(0, file, buffer, count, pos);
}

static ssize_t irq_affinity_list_proc_write(struct file *file,
		const char __user *buffer, size_t count, loff_t *pos)
{
	return write_irq_affinity(1, file, buffer, count, pos);
}

static int irq_affinity_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, irq_affinity_proc_show, PDE_DATA(inode));
}

static int irq_affinity_list_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, irq_affinity_list_proc_show, PDE_DATA(inode));
}

static const struct file_operations irq_affinity_proc_fops = {
	.open		= irq_affinity_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.write		= irq_affinity_proc_write,
};

static const struct file_operations irq_affinity_list_proc_fops = {
	.open		= irq_affinity_list_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.write		= irq_affinity_list_proc_write,
};

#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
static int irq_effective_aff_proc_show(struct seq_file *m, void *v)
{
	return show_irq_affinity(EFFECTIVE, m);
}

static int irq_effective_aff_list_proc_show(struct seq_file *m, void *v)
{
	return show_irq_affinity(EFFECTIVE_LIST, m);
}
#endif

static int default_affinity_show(struct seq_file *m, void *v)
{
	seq_printf(m, "%*pb\n", cpumask_pr_args(irq_default_affinity));
	return 0;
}

static ssize_t default_affinity_write(struct file *file,
		const char __user *buffer, size_t count, loff_t *ppos)
{
	cpumask_var_t new_value;
	int err;

	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
		return -ENOMEM;

	err = cpumask_parse_user(buffer, count, new_value);
	if (err)
		goto out;

	/*
	 * Do not allow disabling IRQs completely - it's a too easy
	 * way to make the system unusable accidentally :-) At least
	 * one online CPU still has to be targeted.
	 */
	if (!cpumask_intersects(new_value, cpu_online_mask)) {
		err = -EINVAL;
		goto out;
	}

	cpumask_copy(irq_default_affinity, new_value);
	err = count;

out:
	free_cpumask_var(new_value);
	return err;
}

static int default_affinity_open(struct inode *inode, struct file *file)
{
	return single_open(file, default_affinity_show, PDE_DATA(inode));
}

static const struct file_operations default_affinity_proc_fops = {
	.open		= default_affinity_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
	.write		= default_affinity_write,
};

static int irq_node_proc_show(struct seq_file *m, void *v)
{
	struct irq_desc *desc = irq_to_desc((long) m->private);

	seq_printf(m, "%d\n", irq_desc_get_node(desc));
	return 0;
}
#endif

static int irq_spurious_proc_show(struct seq_file *m, void *v)
{
	struct irq_desc *desc = irq_to_desc((long) m->private);

	seq_printf(m, "count %u\n" "unhandled %u\n" "last_unhandled %u ms\n",
		   desc->irq_count, desc->irqs_unhandled,
		   jiffies_to_msecs(desc->last_unhandled));
	return 0;
}

#define MAX_NAMELEN 128

static int name_unique(unsigned int irq, struct irqaction *new_action)
{
	struct irq_desc *desc = irq_to_desc(irq);
	struct irqaction *action;
	unsigned long flags;
	int ret = 1;

	raw_spin_lock_irqsave(&desc->lock, flags);
	for_each_action_of_desc(desc, action) {
		if ((action != new_action) && action->name &&
				!strcmp(new_action->name, action->name)) {
			ret = 0;
			break;
		}
	}
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	return ret;
}

void register_handler_proc(unsigned int irq, struct irqaction *action)
{
	char name [MAX_NAMELEN];
	struct irq_desc *desc = irq_to_desc(irq);

	if (!desc->dir || action->dir || !action->name ||
					!name_unique(irq, action))
		return;

	snprintf(name, MAX_NAMELEN, "%s", action->name);

	/* create /proc/irq/1234/handler/ */
	action->dir = proc_mkdir(name, desc->dir);
}

#undef MAX_NAMELEN

#define MAX_NAMELEN 10

void register_irq_proc(unsigned int irq, struct irq_desc *desc)
{
	static DEFINE_MUTEX(register_lock);
	void __maybe_unused *irqp = (void *)(unsigned long) irq;
	char name [MAX_NAMELEN];

	if (!root_irq_dir || (desc->irq_data.chip == &no_irq_chip))
		return;

	/*
	 * irq directories are registered only when a handler is
	 * added, not when the descriptor is created, so multiple
	 * tasks might try to register at the same time.
	 */
	mutex_lock(&register_lock);

	if (desc->dir)
		goto out_unlock;

	sprintf(name, "%d", irq);

	/* create /proc/irq/1234 */
	desc->dir = proc_mkdir(name, root_irq_dir);
	if (!desc->dir)
		goto out_unlock;

#ifdef CONFIG_SMP
	/* create /proc/irq/<irq>/smp_affinity */
	proc_create_data("smp_affinity", 0644, desc->dir,
			 &irq_affinity_proc_fops, irqp);

	/* create /proc/irq/<irq>/affinity_hint */
	proc_create_single_data("affinity_hint", 0444, desc->dir,
			irq_affinity_hint_proc_show, irqp);

	/* create /proc/irq/<irq>/smp_affinity_list */
	proc_create_data("smp_affinity_list", 0644, desc->dir,
			 &irq_affinity_list_proc_fops, irqp);

	proc_create_single_data("node", 0444, desc->dir, irq_node_proc_show,
			irqp);
# ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	proc_create_single_data("effective_affinity", 0444, desc->dir,
			irq_effective_aff_proc_show, irqp);
	proc_create_single_data("effective_affinity_list", 0444, desc->dir,
			irq_effective_aff_list_proc_show, irqp);
# endif
#endif
	proc_create_single_data("spurious", 0444, desc->dir,
			irq_spurious_proc_show, (void *)(long)irq);

out_unlock:
	mutex_unlock(&register_lock);
}

void unregister_irq_proc(unsigned int irq, struct irq_desc *desc)
{
	char name [MAX_NAMELEN];

	if (!root_irq_dir || !desc->dir)
		return;
#ifdef CONFIG_SMP
	remove_proc_entry("smp_affinity", desc->dir);
	remove_proc_entry("affinity_hint", desc->dir);
	remove_proc_entry("smp_affinity_list", desc->dir);
	remove_proc_entry("node", desc->dir);
# ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
	remove_proc_entry("effective_affinity", desc->dir);
	remove_proc_entry("effective_affinity_list", desc->dir);
# endif
#endif
	remove_proc_entry("spurious", desc->dir);

	sprintf(name, "%u", irq);
	remove_proc_entry(name, root_irq_dir);
}

#undef MAX_NAMELEN

void unregister_handler_proc(unsigned int irq, struct irqaction *action)
{
	proc_remove(action->dir);
}

static void register_default_affinity_proc(void)
{
#ifdef CONFIG_SMP
	proc_create("irq/default_smp_affinity", 0644, NULL,
		    &default_affinity_proc_fops);
#endif
}

void init_irq_proc(void)
{
	unsigned int irq;
	struct irq_desc *desc;

	/* create /proc/irq */
	root_irq_dir = proc_mkdir("irq", NULL);
	if (!root_irq_dir)
		return;

	register_default_affinity_proc();

	/*
	 * Create entries for all existing IRQs.
	 */
	for_each_irq_desc(irq, desc)
		register_irq_proc(irq, desc);
}

#ifdef CONFIG_GENERIC_IRQ_SHOW

int __weak arch_show_interrupts(struct seq_file *p, int prec)
{
	return 0;
}

#ifndef ACTUAL_NR_IRQS
# define ACTUAL_NR_IRQS nr_irqs
#endif

int show_interrupts(struct seq_file *p, void *v)
{
	static int prec;

	unsigned long flags, any_count = 0;
	int i = *(loff_t *) v, j;
	struct irqaction *action;
	struct irq_desc *desc;

	if (i > ACTUAL_NR_IRQS)
		return 0;

	if (i == ACTUAL_NR_IRQS)
		return arch_show_interrupts(p, prec);

	/* print header and calculate the width of the first column */
	if (i == 0) {
		for (prec = 3, j = 1000; prec < 10 && j <= nr_irqs; ++prec)
			j *= 10;

		seq_printf(p, "%*s", prec + 8, "");
		for_each_online_cpu(j)
			seq_printf(p, "CPU%-8d", j);
		seq_putc(p, '\n');
	}

	rcu_read_lock();
	desc = irq_to_desc(i);
	if (!desc)
		goto outsparse;

	if (desc->kstat_irqs)
		for_each_online_cpu(j)
			any_count |= *per_cpu_ptr(desc->kstat_irqs, j);

	if ((!desc->action || irq_desc_is_chained(desc)) && !any_count)
		goto outsparse;

	seq_printf(p, "%*d: ", prec, i);
	for_each_online_cpu(j)
		seq_printf(p, "%10u ", desc->kstat_irqs ?
					*per_cpu_ptr(desc->kstat_irqs, j) : 0);

	raw_spin_lock_irqsave(&desc->lock, flags);
	if (desc->irq_data.chip) {
		if (desc->irq_data.chip->irq_print_chip)
			desc->irq_data.chip->irq_print_chip(&desc->irq_data, p);
		else if (desc->irq_data.chip->name)
			seq_printf(p, " %8s", desc->irq_data.chip->name);
		else
			seq_printf(p, " %8s", "-");
	} else {
		seq_printf(p, " %8s", "None");
	}
	if (desc->irq_data.domain)
		seq_printf(p, " %*d", prec, (int) desc->irq_data.hwirq);
	else
		seq_printf(p, " %*s", prec, "");
#ifdef CONFIG_GENERIC_IRQ_SHOW_LEVEL
	seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");
#endif
	if (desc->name)
		seq_printf(p, "-%-8s", desc->name);

	action = desc->action;
	if (action) {
		seq_printf(p, "  %s", action->name);
		while ((action = action->next) != NULL)
			seq_printf(p, ", %s", action->name);
	}

	seq_putc(p, '\n');
	raw_spin_unlock_irqrestore(&desc->lock, flags);
outsparse:
	rcu_read_unlock();
	return 0;
}
#endif