linux/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.h>
#include <linux/kernel_stat.h>
#include <linux/mutex.h>
#include <linux/string.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;

	guard(raw_spinlock_irq)(&desc->lock);

	switch (type) {
	case AFFINITY:
	case AFFINITY_LIST:
		mask = desc->irq_common_data.affinity;
		if (irq_move_pending(&desc->irq_data))
			mask = irq_desc_get_pending_mask(desc);
		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);
	cpumask_var_t mask;

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

	scoped_guard(raw_spinlock_irq, &desc->lock) {
		if (desc->affinity_hint)
			cpumask_copy(mask, desc->affinity_hint);
	}

	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 -EPERM;

	if (!zalloc_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 proc_ops irq_affinity_proc_ops = {
	.proc_open	= irq_affinity_proc_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= single_release,
	.proc_write	= irq_affinity_proc_write,
};

static const struct proc_ops irq_affinity_list_proc_ops = {
	.proc_open	= irq_affinity_list_proc_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= single_release,
	.proc_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 (!zalloc_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 proc_ops default_affinity_proc_ops = {
	.proc_open	= default_affinity_open,
	.proc_read	= seq_read,
	.proc_lseek	= seq_lseek,
	.proc_release	= single_release,
	.proc_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 bool name_unique(unsigned int irq, struct irqaction *new_action)
{
	struct irq_desc *desc = irq_to_desc(irq);
	struct irqaction *action;

	guard(raw_spinlock_irq)(&desc->lock);
	for_each_action_of_desc(desc, action) {
		if ((action != new_action) && action->name &&
		    !strcmp(new_action->name, action->name))
			return false;
	}
	return true;
}

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;

	strscpy(name, action->name);

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

#undef MAX_NAMELEN

#define MAX_NAMELEN 11

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.
	 */
	guard(mutex)(&register_lock);

	if (desc->dir)
		return;

	/* create /proc/irq/1234 */
	snprintf(name, MAX_NAMELEN, "%u", irq);
	desc->dir = proc_mkdir(name, root_irq_dir);
	if (!desc->dir)
		return;

#ifdef CONFIG_SMP
	umode_t umode = S_IRUGO;

	if (irq_can_set_affinity_usr(desc->irq_data.irq))
		umode |= S_IWUSR;

	/* create /proc/irq/<irq>/smp_affinity */
	proc_create_data("smp_affinity", umode, desc->dir, &irq_affinity_proc_ops, 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", umode, desc->dir,
			 &irq_affinity_list_proc_ops, 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);

}

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);

	snprintf(name, MAX_NAMELEN, "%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_ops);
#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);
}

void irq_proc_update_valid(struct irq_desc *desc)
{
	u32 set = _IRQ_PROC_VALID;

	if (irq_settings_is_hidden(desc) || irq_desc_is_chained(desc) || !desc->action)
		set = 0;

	irq_settings_update_proc_valid(desc, set);
}

#ifdef CONFIG_GENERIC_IRQ_SHOW

#define ARCH_PROC_IRQDESC ((void *)0x00001111)

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

static DEFINE_RAW_SPINLOCK(irq_proc_constraints_lock);

static struct irq_proc_constraints {
	bool		print_header;
	unsigned int	num_prec;
	unsigned int	chip_width;
} irq_proc_constraints __read_mostly = {
	.num_prec	= 4,
	.chip_width	= 8,
};

#ifndef ACTUAL_NR_IRQS
# define ACTUAL_NR_IRQS total_nr_irqs
#endif

void irq_proc_calc_prec(void)
{
	unsigned int prec, n;

	for (prec = 4, n = 10000; prec < 10 && n <= total_nr_irqs; ++prec)
		n *= 10;

	guard(raw_spinlock_irqsave)(&irq_proc_constraints_lock);
	if (prec > irq_proc_constraints.num_prec)
		WRITE_ONCE(irq_proc_constraints.num_prec, prec);
}

void irq_proc_update_chip(const struct irq_chip *chip)
{
	unsigned int len = chip && chip->name ? strlen(chip->name) : 0;

	if (!len || len <= READ_ONCE(irq_proc_constraints.chip_width))
		return;

	/* Can be invoked from interrupt disabled contexts */
	guard(raw_spinlock_irqsave)(&irq_proc_constraints_lock);
	if (len > irq_proc_constraints.chip_width)
		WRITE_ONCE(irq_proc_constraints.chip_width, len);
}

/* Same as seq_put_decimal_ull_width(p, " ", cnt, 10) */
#define ZSTR1 "          0"
#define ZSTR1_LEN	(sizeof(ZSTR1) - 1)
#define ZSTR16		ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 \
			ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1 ZSTR1
#define ZSTR256		ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 \
			ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16 ZSTR16

static inline void irq_proc_emit_zero_counts(struct seq_file *p, unsigned int zeros)
{
	if (!zeros)
		return;

	for (unsigned int n = min(zeros, 256); n; zeros -= n, n = min(zeros, 256))
		seq_write(p, ZSTR256, n * ZSTR1_LEN);
}

static inline unsigned int irq_proc_emit_count(struct seq_file *p, unsigned int cnt,
					       unsigned int zeros)
{
	if (!cnt)
		return zeros + 1;

	irq_proc_emit_zero_counts(p, zeros);
	seq_put_decimal_ull_width(p, " ", cnt, 10);
	return 0;
}

void irq_proc_emit_counts(struct seq_file *p, unsigned int __percpu *cnts)
{
	unsigned int cpu, zeros = 0;

	for_each_online_cpu(cpu)
		zeros = irq_proc_emit_count(p, per_cpu(*cnts, cpu), zeros);
	irq_proc_emit_zero_counts(p, zeros);
}

static int irq_seq_show(struct seq_file *p, void *v)
{
	struct irq_proc_constraints *constr = p->private;
	struct irq_desc *desc = v;
	struct irqaction *action;

	/* Print header for the first interrupt? */
	if (constr->print_header) {
		unsigned int cpu;

		seq_printf(p, "%*s", constr->num_prec + 8, "");
		for_each_online_cpu(cpu)
			seq_printf(p, "CPU%-8d", cpu);
		seq_putc(p, '\n');
		constr->print_header = false;
	}

	if (desc == ARCH_PROC_IRQDESC)
		return arch_show_interrupts(p, constr->num_prec);

	seq_put_decimal_ull_width(p, "", irq_desc_get_irq(desc), constr->num_prec);
	seq_putc(p, ':');

	/*
	 * Always output per CPU interrupts. Output device interrupts only when
	 * desc::tot_count is not zero.
	 */
	if (irq_settings_is_per_cpu(desc) || irq_settings_is_per_cpu_devid(desc) ||
	    data_race(desc->tot_count))
		irq_proc_emit_counts(p, &desc->kstat_irqs->cnt);
	else
		irq_proc_emit_zero_counts(p, num_online_cpus());

	/* Enforce a visual gap */
	seq_write(p, "  ", 2);

	guard(raw_spinlock_irq)(&desc->lock);
	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, "%-*s", constr->chip_width, desc->irq_data.chip->name);
		else
			seq_printf(p, "%-*s", constr->chip_width, "-");
	} else {
		seq_printf(p, "%-*s", constr->chip_width, "None");
	}

	seq_putc(p, ' ');
	if (desc->irq_data.domain)
		seq_put_decimal_ull_width(p, "", desc->irq_data.hwirq, constr->num_prec);
	else
		seq_printf(p, " %*s", constr->num_prec, "");

	if (IS_ENABLED(CONFIG_GENERIC_IRQ_SHOW_LEVEL))
		seq_printf(p, " %-8s", irqd_is_level_type(&desc->irq_data) ? "Level" : "Edge");

	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');
	return 0;
}

static void *irq_seq_next_desc(loff_t *pos)
{
	if (*pos > total_nr_irqs)
		return NULL;

	guard(rcu)();
	for (;;) {
		struct irq_desc *desc = irq_find_desc_at_or_after((unsigned int) *pos);

		if (desc) {
			*pos = irq_desc_get_irq(desc);
			/*
			 * If valid for output then try to acquire a reference
			 * count on the descriptor so that it can't be freed
			 * after dropping RCU read lock on return.
			 */
			if (irq_settings_proc_valid(desc) && irq_desc_get_ref(desc))
				return desc;
			(*pos)++;
		} else {
			*pos = total_nr_irqs;
			return ARCH_PROC_IRQDESC;
		}
	}
}

static void *irq_seq_start(struct seq_file *f, loff_t *pos)
{
	if (!*pos) {
		struct irq_proc_constraints *constr = f->private;

		constr->num_prec = READ_ONCE(irq_proc_constraints.num_prec);
		constr->chip_width = READ_ONCE(irq_proc_constraints.chip_width);
		constr->print_header = true;
	}
	return irq_seq_next_desc(pos);
}

static void *irq_seq_next(struct seq_file *f, void *v, loff_t *pos)
{
	if (v && v != ARCH_PROC_IRQDESC)
		irq_desc_put_ref(v);

	(*pos)++;
	return irq_seq_next_desc(pos);
}

static void irq_seq_stop(struct seq_file *f, void *v)
{
	if (v && v != ARCH_PROC_IRQDESC)
		irq_desc_put_ref(v);
}

static const struct seq_operations irq_seq_ops = {
	.start = irq_seq_start,
	.next  = irq_seq_next,
	.stop  = irq_seq_stop,
	.show  = irq_seq_show,
};

static int __init irq_proc_init(void)
{
	proc_create_seq_private("interrupts", 0, NULL, &irq_seq_ops,
				sizeof(irq_proc_constraints), NULL);
	return 0;
}
fs_initcall(irq_proc_init);

#endif