743 строки
17 KiB
C
743 строки
17 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2017 - Cambridge Greys Ltd
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* Copyright (C) 2011 - 2014 Cisco Systems Inc
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* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Derived (i.e. mostly copied) from arch/i386/kernel/irq.c:
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* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
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*/
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#include <linux/cpumask.h>
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#include <linux/hardirq.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/seq_file.h>
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#include <linux/slab.h>
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#include <as-layout.h>
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#include <kern_util.h>
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#include <os.h>
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#include <irq_user.h>
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#include <irq_kern.h>
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#include <linux/time-internal.h>
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extern void free_irqs(void);
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/* When epoll triggers we do not know why it did so
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* we can also have different IRQs for read and write.
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* This is why we keep a small irq_reg array for each fd -
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* one entry per IRQ type
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*/
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struct irq_reg {
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void *id;
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int irq;
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/* it's cheaper to store this than to query it */
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int events;
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bool active;
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bool pending;
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bool wakeup;
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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bool pending_on_resume;
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void (*timetravel_handler)(int, int, void *,
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struct time_travel_event *);
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struct time_travel_event event;
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#endif
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};
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struct irq_entry {
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struct list_head list;
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int fd;
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struct irq_reg reg[NUM_IRQ_TYPES];
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bool suspended;
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bool sigio_workaround;
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};
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static DEFINE_SPINLOCK(irq_lock);
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static LIST_HEAD(active_fds);
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static DECLARE_BITMAP(irqs_allocated, NR_IRQS);
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static bool irqs_suspended;
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static void irq_io_loop(struct irq_reg *irq, struct uml_pt_regs *regs)
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{
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/*
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* irq->active guards against reentry
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* irq->pending accumulates pending requests
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* if pending is raised the irq_handler is re-run
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* until pending is cleared
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*/
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if (irq->active) {
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irq->active = false;
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do {
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irq->pending = false;
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do_IRQ(irq->irq, regs);
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} while (irq->pending);
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irq->active = true;
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} else {
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irq->pending = true;
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}
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}
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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static void irq_event_handler(struct time_travel_event *ev)
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{
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struct irq_reg *reg = container_of(ev, struct irq_reg, event);
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/* do nothing if suspended - just to cause a wakeup */
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if (irqs_suspended)
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return;
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generic_handle_irq(reg->irq);
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}
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static bool irq_do_timetravel_handler(struct irq_entry *entry,
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enum um_irq_type t)
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{
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struct irq_reg *reg = &entry->reg[t];
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if (!reg->timetravel_handler)
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return false;
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/* prevent nesting - we'll get it again later when we SIGIO ourselves */
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if (reg->pending_on_resume)
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return true;
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reg->timetravel_handler(reg->irq, entry->fd, reg->id, ®->event);
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if (!reg->event.pending)
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return false;
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if (irqs_suspended)
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reg->pending_on_resume = true;
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return true;
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}
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#else
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static bool irq_do_timetravel_handler(struct irq_entry *entry,
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enum um_irq_type t)
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{
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return false;
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}
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#endif
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static void sigio_reg_handler(int idx, struct irq_entry *entry, enum um_irq_type t,
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struct uml_pt_regs *regs)
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{
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struct irq_reg *reg = &entry->reg[t];
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if (!reg->events)
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return;
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if (os_epoll_triggered(idx, reg->events) <= 0)
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return;
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if (irq_do_timetravel_handler(entry, t))
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return;
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if (irqs_suspended)
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return;
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irq_io_loop(reg, regs);
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}
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void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
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{
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struct irq_entry *irq_entry;
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int n, i;
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if (irqs_suspended && !um_irq_timetravel_handler_used())
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return;
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while (1) {
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/* This is now lockless - epoll keeps back-referencesto the irqs
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* which have trigger it so there is no need to walk the irq
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* list and lock it every time. We avoid locking by turning off
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* IO for a specific fd by executing os_del_epoll_fd(fd) before
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* we do any changes to the actual data structures
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*/
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n = os_waiting_for_events_epoll();
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if (n <= 0) {
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if (n == -EINTR)
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continue;
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else
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break;
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}
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for (i = 0; i < n ; i++) {
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enum um_irq_type t;
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irq_entry = os_epoll_get_data_pointer(i);
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for (t = 0; t < NUM_IRQ_TYPES; t++)
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sigio_reg_handler(i, irq_entry, t, regs);
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}
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}
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if (!irqs_suspended)
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free_irqs();
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}
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static struct irq_entry *get_irq_entry_by_fd(int fd)
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{
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struct irq_entry *walk;
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lockdep_assert_held(&irq_lock);
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list_for_each_entry(walk, &active_fds, list) {
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if (walk->fd == fd)
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return walk;
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}
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return NULL;
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}
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static void free_irq_entry(struct irq_entry *to_free, bool remove)
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{
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if (!to_free)
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return;
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if (remove)
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os_del_epoll_fd(to_free->fd);
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list_del(&to_free->list);
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kfree(to_free);
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}
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static bool update_irq_entry(struct irq_entry *entry)
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{
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enum um_irq_type i;
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int events = 0;
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for (i = 0; i < NUM_IRQ_TYPES; i++)
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events |= entry->reg[i].events;
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if (events) {
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/* will modify (instead of add) if needed */
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os_add_epoll_fd(events, entry->fd, entry);
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return true;
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}
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os_del_epoll_fd(entry->fd);
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return false;
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}
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static void update_or_free_irq_entry(struct irq_entry *entry)
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{
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if (!update_irq_entry(entry))
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free_irq_entry(entry, false);
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}
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static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
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void (*timetravel_handler)(int, int, void *,
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struct time_travel_event *))
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{
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struct irq_entry *irq_entry;
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int err, events = os_event_mask(type);
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unsigned long flags;
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err = os_set_fd_async(fd);
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if (err < 0)
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goto out;
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spin_lock_irqsave(&irq_lock, flags);
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irq_entry = get_irq_entry_by_fd(fd);
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if (irq_entry) {
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/* cannot register the same FD twice with the same type */
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if (WARN_ON(irq_entry->reg[type].events)) {
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err = -EALREADY;
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goto out_unlock;
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}
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/* temporarily disable to avoid IRQ-side locking */
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os_del_epoll_fd(fd);
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} else {
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irq_entry = kzalloc(sizeof(*irq_entry), GFP_ATOMIC);
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if (!irq_entry) {
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err = -ENOMEM;
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goto out_unlock;
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}
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irq_entry->fd = fd;
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list_add_tail(&irq_entry->list, &active_fds);
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maybe_sigio_broken(fd);
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}
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irq_entry->reg[type].id = dev_id;
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irq_entry->reg[type].irq = irq;
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irq_entry->reg[type].active = true;
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irq_entry->reg[type].events = events;
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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if (um_irq_timetravel_handler_used()) {
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irq_entry->reg[type].timetravel_handler = timetravel_handler;
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irq_entry->reg[type].event.fn = irq_event_handler;
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}
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#endif
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WARN_ON(!update_irq_entry(irq_entry));
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spin_unlock_irqrestore(&irq_lock, flags);
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return 0;
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out_unlock:
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spin_unlock_irqrestore(&irq_lock, flags);
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out:
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return err;
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}
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/*
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* Remove the entry or entries for a specific FD, if you
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* don't want to remove all the possible entries then use
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* um_free_irq() or deactivate_fd() instead.
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*/
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void free_irq_by_fd(int fd)
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{
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struct irq_entry *to_free;
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unsigned long flags;
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spin_lock_irqsave(&irq_lock, flags);
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to_free = get_irq_entry_by_fd(fd);
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free_irq_entry(to_free, true);
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spin_unlock_irqrestore(&irq_lock, flags);
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}
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EXPORT_SYMBOL(free_irq_by_fd);
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static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
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{
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struct irq_entry *entry;
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unsigned long flags;
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spin_lock_irqsave(&irq_lock, flags);
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list_for_each_entry(entry, &active_fds, list) {
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enum um_irq_type i;
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for (i = 0; i < NUM_IRQ_TYPES; i++) {
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struct irq_reg *reg = &entry->reg[i];
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if (!reg->events)
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continue;
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if (reg->irq != irq)
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continue;
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if (reg->id != dev)
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continue;
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os_del_epoll_fd(entry->fd);
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reg->events = 0;
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update_or_free_irq_entry(entry);
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goto out;
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}
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}
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out:
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spin_unlock_irqrestore(&irq_lock, flags);
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}
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void deactivate_fd(int fd, int irqnum)
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{
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struct irq_entry *entry;
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unsigned long flags;
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enum um_irq_type i;
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os_del_epoll_fd(fd);
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spin_lock_irqsave(&irq_lock, flags);
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entry = get_irq_entry_by_fd(fd);
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if (!entry)
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goto out;
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for (i = 0; i < NUM_IRQ_TYPES; i++) {
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if (!entry->reg[i].events)
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continue;
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if (entry->reg[i].irq == irqnum)
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entry->reg[i].events = 0;
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}
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update_or_free_irq_entry(entry);
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out:
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spin_unlock_irqrestore(&irq_lock, flags);
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ignore_sigio_fd(fd);
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}
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EXPORT_SYMBOL(deactivate_fd);
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/*
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* Called just before shutdown in order to provide a clean exec
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* environment in case the system is rebooting. No locking because
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* that would cause a pointless shutdown hang if something hadn't
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* released the lock.
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*/
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int deactivate_all_fds(void)
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{
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struct irq_entry *entry;
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/* Stop IO. The IRQ loop has no lock so this is our
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* only way of making sure we are safe to dispose
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* of all IRQ handlers
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*/
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os_set_ioignore();
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/* we can no longer call kfree() here so just deactivate */
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list_for_each_entry(entry, &active_fds, list)
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os_del_epoll_fd(entry->fd);
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os_close_epoll_fd();
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return 0;
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}
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/*
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* do_IRQ handles all normal device IRQs (the special
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* SMP cross-CPU interrupts have their own specific
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* handlers).
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*/
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unsigned int do_IRQ(int irq, struct uml_pt_regs *regs)
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{
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struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs);
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irq_enter();
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generic_handle_irq(irq);
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irq_exit();
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set_irq_regs(old_regs);
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return 1;
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}
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void um_free_irq(int irq, void *dev)
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{
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if (WARN(irq < 0 || irq > NR_IRQS, "freeing invalid irq %d", irq))
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return;
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free_irq_by_irq_and_dev(irq, dev);
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free_irq(irq, dev);
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clear_bit(irq, irqs_allocated);
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}
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EXPORT_SYMBOL(um_free_irq);
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static int
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_um_request_irq(int irq, int fd, enum um_irq_type type,
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irq_handler_t handler, unsigned long irqflags,
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const char *devname, void *dev_id,
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void (*timetravel_handler)(int, int, void *,
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struct time_travel_event *))
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{
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int err;
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if (irq == UM_IRQ_ALLOC) {
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int i;
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for (i = UM_FIRST_DYN_IRQ; i < NR_IRQS; i++) {
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if (!test_and_set_bit(i, irqs_allocated)) {
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irq = i;
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break;
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}
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}
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}
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if (irq < 0)
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return -ENOSPC;
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if (fd != -1) {
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err = activate_fd(irq, fd, type, dev_id, timetravel_handler);
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if (err)
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goto error;
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}
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err = request_irq(irq, handler, irqflags, devname, dev_id);
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if (err < 0)
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goto error;
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return irq;
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error:
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clear_bit(irq, irqs_allocated);
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return err;
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}
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int um_request_irq(int irq, int fd, enum um_irq_type type,
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irq_handler_t handler, unsigned long irqflags,
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const char *devname, void *dev_id)
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{
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return _um_request_irq(irq, fd, type, handler, irqflags,
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devname, dev_id, NULL);
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}
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EXPORT_SYMBOL(um_request_irq);
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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int um_request_irq_tt(int irq, int fd, enum um_irq_type type,
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irq_handler_t handler, unsigned long irqflags,
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const char *devname, void *dev_id,
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void (*timetravel_handler)(int, int, void *,
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struct time_travel_event *))
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{
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return _um_request_irq(irq, fd, type, handler, irqflags,
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devname, dev_id, timetravel_handler);
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}
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EXPORT_SYMBOL(um_request_irq_tt);
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#endif
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#ifdef CONFIG_PM_SLEEP
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void um_irqs_suspend(void)
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{
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struct irq_entry *entry;
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unsigned long flags;
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irqs_suspended = true;
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spin_lock_irqsave(&irq_lock, flags);
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list_for_each_entry(entry, &active_fds, list) {
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enum um_irq_type t;
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bool clear = true;
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for (t = 0; t < NUM_IRQ_TYPES; t++) {
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if (!entry->reg[t].events)
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continue;
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/*
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* For the SIGIO_WRITE_IRQ, which is used to handle the
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* SIGIO workaround thread, we need special handling:
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* enable wake for it itself, but below we tell it about
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* any FDs that should be suspended.
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*/
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if (entry->reg[t].wakeup ||
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entry->reg[t].irq == SIGIO_WRITE_IRQ
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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|| entry->reg[t].timetravel_handler
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#endif
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) {
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clear = false;
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break;
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}
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}
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if (clear) {
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entry->suspended = true;
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os_clear_fd_async(entry->fd);
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entry->sigio_workaround =
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!__ignore_sigio_fd(entry->fd);
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}
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}
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spin_unlock_irqrestore(&irq_lock, flags);
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}
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void um_irqs_resume(void)
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{
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struct irq_entry *entry;
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unsigned long flags;
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local_irq_save(flags);
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#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
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/*
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* We don't need to lock anything here since we're in resume
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* and nothing else is running, but have disabled IRQs so we
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* don't try anything else with the interrupt list from there.
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*/
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list_for_each_entry(entry, &active_fds, list) {
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enum um_irq_type t;
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for (t = 0; t < NUM_IRQ_TYPES; t++) {
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struct irq_reg *reg = &entry->reg[t];
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if (reg->pending_on_resume) {
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irq_enter();
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generic_handle_irq(reg->irq);
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irq_exit();
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reg->pending_on_resume = false;
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}
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}
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}
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#endif
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spin_lock(&irq_lock);
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list_for_each_entry(entry, &active_fds, list) {
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if (entry->suspended) {
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int err = os_set_fd_async(entry->fd);
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WARN(err < 0, "os_set_fd_async returned %d\n", err);
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entry->suspended = false;
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|
|
|
if (entry->sigio_workaround) {
|
|
err = __add_sigio_fd(entry->fd);
|
|
WARN(err < 0, "add_sigio_returned %d\n", err);
|
|
}
|
|
}
|
|
}
|
|
spin_unlock_irqrestore(&irq_lock, flags);
|
|
|
|
irqs_suspended = false;
|
|
send_sigio_to_self();
|
|
}
|
|
|
|
static int normal_irq_set_wake(struct irq_data *d, unsigned int on)
|
|
{
|
|
struct irq_entry *entry;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&irq_lock, flags);
|
|
list_for_each_entry(entry, &active_fds, list) {
|
|
enum um_irq_type t;
|
|
|
|
for (t = 0; t < NUM_IRQ_TYPES; t++) {
|
|
if (!entry->reg[t].events)
|
|
continue;
|
|
|
|
if (entry->reg[t].irq != d->irq)
|
|
continue;
|
|
entry->reg[t].wakeup = on;
|
|
goto unlock;
|
|
}
|
|
}
|
|
unlock:
|
|
spin_unlock_irqrestore(&irq_lock, flags);
|
|
return 0;
|
|
}
|
|
#else
|
|
#define normal_irq_set_wake NULL
|
|
#endif
|
|
|
|
/*
|
|
* irq_chip must define at least enable/disable and ack when
|
|
* the edge handler is used.
|
|
*/
|
|
static void dummy(struct irq_data *d)
|
|
{
|
|
}
|
|
|
|
/* This is used for everything other than the timer. */
|
|
static struct irq_chip normal_irq_type = {
|
|
.name = "SIGIO",
|
|
.irq_disable = dummy,
|
|
.irq_enable = dummy,
|
|
.irq_ack = dummy,
|
|
.irq_mask = dummy,
|
|
.irq_unmask = dummy,
|
|
.irq_set_wake = normal_irq_set_wake,
|
|
};
|
|
|
|
static struct irq_chip alarm_irq_type = {
|
|
.name = "SIGALRM",
|
|
.irq_disable = dummy,
|
|
.irq_enable = dummy,
|
|
.irq_ack = dummy,
|
|
.irq_mask = dummy,
|
|
.irq_unmask = dummy,
|
|
};
|
|
|
|
void __init init_IRQ(void)
|
|
{
|
|
int i;
|
|
|
|
irq_set_chip_and_handler(TIMER_IRQ, &alarm_irq_type, handle_edge_irq);
|
|
|
|
for (i = 1; i < NR_IRQS; i++)
|
|
irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
|
|
/* Initialize EPOLL Loop */
|
|
os_setup_epoll();
|
|
}
|
|
|
|
/*
|
|
* IRQ stack entry and exit:
|
|
*
|
|
* Unlike i386, UML doesn't receive IRQs on the normal kernel stack
|
|
* and switch over to the IRQ stack after some preparation. We use
|
|
* sigaltstack to receive signals on a separate stack from the start.
|
|
* These two functions make sure the rest of the kernel won't be too
|
|
* upset by being on a different stack. The IRQ stack has a
|
|
* thread_info structure at the bottom so that current et al continue
|
|
* to work.
|
|
*
|
|
* to_irq_stack copies the current task's thread_info to the IRQ stack
|
|
* thread_info and sets the tasks's stack to point to the IRQ stack.
|
|
*
|
|
* from_irq_stack copies the thread_info struct back (flags may have
|
|
* been modified) and resets the task's stack pointer.
|
|
*
|
|
* Tricky bits -
|
|
*
|
|
* What happens when two signals race each other? UML doesn't block
|
|
* signals with sigprocmask, SA_DEFER, or sa_mask, so a second signal
|
|
* could arrive while a previous one is still setting up the
|
|
* thread_info.
|
|
*
|
|
* There are three cases -
|
|
* The first interrupt on the stack - sets up the thread_info and
|
|
* handles the interrupt
|
|
* A nested interrupt interrupting the copying of the thread_info -
|
|
* can't handle the interrupt, as the stack is in an unknown state
|
|
* A nested interrupt not interrupting the copying of the
|
|
* thread_info - doesn't do any setup, just handles the interrupt
|
|
*
|
|
* The first job is to figure out whether we interrupted stack setup.
|
|
* This is done by xchging the signal mask with thread_info->pending.
|
|
* If the value that comes back is zero, then there is no setup in
|
|
* progress, and the interrupt can be handled. If the value is
|
|
* non-zero, then there is stack setup in progress. In order to have
|
|
* the interrupt handled, we leave our signal in the mask, and it will
|
|
* be handled by the upper handler after it has set up the stack.
|
|
*
|
|
* Next is to figure out whether we are the outer handler or a nested
|
|
* one. As part of setting up the stack, thread_info->real_thread is
|
|
* set to non-NULL (and is reset to NULL on exit). This is the
|
|
* nesting indicator. If it is non-NULL, then the stack is already
|
|
* set up and the handler can run.
|
|
*/
|
|
|
|
static unsigned long pending_mask;
|
|
|
|
unsigned long to_irq_stack(unsigned long *mask_out)
|
|
{
|
|
struct thread_info *ti;
|
|
unsigned long mask, old;
|
|
int nested;
|
|
|
|
mask = xchg(&pending_mask, *mask_out);
|
|
if (mask != 0) {
|
|
/*
|
|
* If any interrupts come in at this point, we want to
|
|
* make sure that their bits aren't lost by our
|
|
* putting our bit in. So, this loop accumulates bits
|
|
* until xchg returns the same value that we put in.
|
|
* When that happens, there were no new interrupts,
|
|
* and pending_mask contains a bit for each interrupt
|
|
* that came in.
|
|
*/
|
|
old = *mask_out;
|
|
do {
|
|
old |= mask;
|
|
mask = xchg(&pending_mask, old);
|
|
} while (mask != old);
|
|
return 1;
|
|
}
|
|
|
|
ti = current_thread_info();
|
|
nested = (ti->real_thread != NULL);
|
|
if (!nested) {
|
|
struct task_struct *task;
|
|
struct thread_info *tti;
|
|
|
|
task = cpu_tasks[ti->cpu].task;
|
|
tti = task_thread_info(task);
|
|
|
|
*ti = *tti;
|
|
ti->real_thread = tti;
|
|
task->stack = ti;
|
|
}
|
|
|
|
mask = xchg(&pending_mask, 0);
|
|
*mask_out |= mask | nested;
|
|
return 0;
|
|
}
|
|
|
|
unsigned long from_irq_stack(int nested)
|
|
{
|
|
struct thread_info *ti, *to;
|
|
unsigned long mask;
|
|
|
|
ti = current_thread_info();
|
|
|
|
pending_mask = 1;
|
|
|
|
to = ti->real_thread;
|
|
current->stack = to;
|
|
ti->real_thread = NULL;
|
|
*to = *ti;
|
|
|
|
mask = xchg(&pending_mask, 0);
|
|
return mask & ~1;
|
|
}
|
|
|