kernel/irq/proc.c

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

        if (desc->dir)
                return;

        /* create /proc/irq/1234 */
        sprintf(name, "%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);

        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_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);
}

#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 irq_get_nr_irqs()
#endif

int show_interrupts(struct seq_file *p, void *v)
{
        const unsigned int nr_irqs = irq_get_nr_irqs();
        static int prec;

        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');
        }

        guard(rcu)();
        desc = irq_to_desc(i);
        if (!desc || irq_settings_is_hidden(desc))
                return 0;

        if (!desc->action || irq_desc_is_chained(desc) || !desc->kstat_irqs)
                return 0;

        seq_printf(p, "%*d:", prec, i);
        for_each_online_cpu(j) {
                unsigned int cnt = desc->kstat_irqs ? per_cpu(desc->kstat_irqs->cnt, j) : 0;

                seq_put_decimal_ull_width(p, " ", cnt, 10);
        }
        seq_putc(p, ' ');

        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, "%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, " %*lu", prec, 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');
        return 0;
}
#endif
Linux
