Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 768 insertions, 0 deletions

diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
new file mode 100644
index 000000000..a8873d9bc
--- /dev/null
+++ b/arch/um/kernel/irq.c
@@ -0,0 +1,768 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017 - Cambridge Greys Ltd
+ * Copyright (C) 2011 - 2014 Cisco Systems Inc
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Derived (i.e. mostly copied) from arch/i386/kernel/irq.c:
+ *	Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
+ */
+
+#include <linux/cpumask.h>
+#include <linux/hardirq.h>
+#include <linux/interrupt.h>
+#include <linux/kernel_stat.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <as-layout.h>
+#include <kern_util.h>
+#include <os.h>
+#include <irq_user.h>
+#include <irq_kern.h>
+#include <linux/time-internal.h>
+
+
+extern void free_irqs(void);
+
+/* When epoll triggers we do not know why it did so
+ * we can also have different IRQs for read and write.
+ * This is why we keep a small irq_reg array for each fd -
+ * one entry per IRQ type
+ */
+struct irq_reg {
+	void *id;
+	int irq;
+	/* it's cheaper to store this than to query it */
+	int events;
+	bool active;
+	bool pending;
+	bool wakeup;
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+	bool pending_on_resume;
+	void (*timetravel_handler)(int, int, void *,
+				   struct time_travel_event *);
+	struct time_travel_event event;
+#endif
+};
+
+struct irq_entry {
+	struct list_head list;
+	int fd;
+	struct irq_reg reg[NUM_IRQ_TYPES];
+	bool suspended;
+	bool sigio_workaround;
+};
+
+static DEFINE_SPINLOCK(irq_lock);
+static LIST_HEAD(active_fds);
+static DECLARE_BITMAP(irqs_allocated, UM_LAST_SIGNAL_IRQ);
+static bool irqs_suspended;
+
+static void irq_io_loop(struct irq_reg *irq, struct uml_pt_regs *regs)
+{
+/*
+ * irq->active guards against reentry
+ * irq->pending accumulates pending requests
+ * if pending is raised the irq_handler is re-run
+ * until pending is cleared
+ */
+	if (irq->active) {
+		irq->active = false;
+
+		do {
+			irq->pending = false;
+			do_IRQ(irq->irq, regs);
+		} while (irq->pending);
+
+		irq->active = true;
+	} else {
+		irq->pending = true;
+	}
+}
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+static void irq_event_handler(struct time_travel_event *ev)
+{
+	struct irq_reg *reg = container_of(ev, struct irq_reg, event);
+
+	/* do nothing if suspended - just to cause a wakeup */
+	if (irqs_suspended)
+		return;
+
+	generic_handle_irq(reg->irq);
+}
+
+static bool irq_do_timetravel_handler(struct irq_entry *entry,
+				      enum um_irq_type t)
+{
+	struct irq_reg *reg = &entry->reg[t];
+
+	if (!reg->timetravel_handler)
+		return false;
+
+	/*
+	 * Handle all messages - we might get multiple even while
+	 * interrupts are already suspended, due to suspend order
+	 * etc. Note that time_travel_add_irq_event() will not add
+	 * an event twice, if it's pending already "first wins".
+	 */
+	reg->timetravel_handler(reg->irq, entry->fd, reg->id, &reg->event);
+
+	if (!reg->event.pending)
+		return false;
+
+	if (irqs_suspended)
+		reg->pending_on_resume = true;
+	return true;
+}
+#else
+static bool irq_do_timetravel_handler(struct irq_entry *entry,
+				      enum um_irq_type t)
+{
+	return false;
+}
+#endif
+
+static void sigio_reg_handler(int idx, struct irq_entry *entry, enum um_irq_type t,
+			      struct uml_pt_regs *regs,
+			      bool timetravel_handlers_only)
+{
+	struct irq_reg *reg = &entry->reg[t];
+
+	if (!reg->events)
+		return;
+
+	if (os_epoll_triggered(idx, reg->events) <= 0)
+		return;
+
+	if (irq_do_timetravel_handler(entry, t))
+		return;
+
+	/*
+	 * If we're called to only run time-travel handlers then don't
+	 * actually proceed but mark sigio as pending (if applicable).
+	 * For suspend/resume, timetravel_handlers_only may be true
+	 * despite time-travel not being configured and used.
+	 */
+	if (timetravel_handlers_only) {
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+		mark_sigio_pending();
+#endif
+		return;
+	}
+
+	irq_io_loop(reg, regs);
+}
+
+static void _sigio_handler(struct uml_pt_regs *regs,
+			   bool timetravel_handlers_only)
+{
+	struct irq_entry *irq_entry;
+	int n, i;
+
+	if (timetravel_handlers_only && !um_irq_timetravel_handler_used())
+		return;
+
+	while (1) {
+		/* This is now lockless - epoll keeps back-referencesto the irqs
+		 * which have trigger it so there is no need to walk the irq
+		 * list and lock it every time. We avoid locking by turning off
+		 * IO for a specific fd by executing os_del_epoll_fd(fd) before
+		 * we do any changes to the actual data structures
+		 */
+		n = os_waiting_for_events_epoll();
+
+		if (n <= 0) {
+			if (n == -EINTR)
+				continue;
+			else
+				break;
+		}
+
+		for (i = 0; i < n ; i++) {
+			enum um_irq_type t;
+
+			irq_entry = os_epoll_get_data_pointer(i);
+
+			for (t = 0; t < NUM_IRQ_TYPES; t++)
+				sigio_reg_handler(i, irq_entry, t, regs,
+						  timetravel_handlers_only);
+		}
+	}
+
+	if (!timetravel_handlers_only)
+		free_irqs();
+}
+
+void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
+{
+	_sigio_handler(regs, irqs_suspended);
+}
+
+static struct irq_entry *get_irq_entry_by_fd(int fd)
+{
+	struct irq_entry *walk;
+
+	lockdep_assert_held(&irq_lock);
+
+	list_for_each_entry(walk, &active_fds, list) {
+		if (walk->fd == fd)
+			return walk;
+	}
+
+	return NULL;
+}
+
+static void free_irq_entry(struct irq_entry *to_free, bool remove)
+{
+	if (!to_free)
+		return;
+
+	if (remove)
+		os_del_epoll_fd(to_free->fd);
+	list_del(&to_free->list);
+	kfree(to_free);
+}
+
+static bool update_irq_entry(struct irq_entry *entry)
+{
+	enum um_irq_type i;
+	int events = 0;
+
+	for (i = 0; i < NUM_IRQ_TYPES; i++)
+		events |= entry->reg[i].events;
+
+	if (events) {
+		/* will modify (instead of add) if needed */
+		os_add_epoll_fd(events, entry->fd, entry);
+		return true;
+	}
+
+	os_del_epoll_fd(entry->fd);
+	return false;
+}
+
+static void update_or_free_irq_entry(struct irq_entry *entry)
+{
+	if (!update_irq_entry(entry))
+		free_irq_entry(entry, false);
+}
+
+static int activate_fd(int irq, int fd, enum um_irq_type type, void *dev_id,
+		       void (*timetravel_handler)(int, int, void *,
+						  struct time_travel_event *))
+{
+	struct irq_entry *irq_entry;
+	int err, events = os_event_mask(type);
+	unsigned long flags;
+
+	err = os_set_fd_async(fd);
+	if (err < 0)
+		goto out;
+
+	spin_lock_irqsave(&irq_lock, flags);
+	irq_entry = get_irq_entry_by_fd(fd);
+	if (irq_entry) {
+		/* cannot register the same FD twice with the same type */
+		if (WARN_ON(irq_entry->reg[type].events)) {
+			err = -EALREADY;
+			goto out_unlock;
+		}
+
+		/* temporarily disable to avoid IRQ-side locking */
+		os_del_epoll_fd(fd);
+	} else {
+		irq_entry = kzalloc(sizeof(*irq_entry), GFP_ATOMIC);
+		if (!irq_entry) {
+			err = -ENOMEM;
+			goto out_unlock;
+		}
+		irq_entry->fd = fd;
+		list_add_tail(&irq_entry->list, &active_fds);
+		maybe_sigio_broken(fd);
+	}
+
+	irq_entry->reg[type].id = dev_id;
+	irq_entry->reg[type].irq = irq;
+	irq_entry->reg[type].active = true;
+	irq_entry->reg[type].events = events;
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+	if (um_irq_timetravel_handler_used()) {
+		irq_entry->reg[type].timetravel_handler = timetravel_handler;
+		irq_entry->reg[type].event.fn = irq_event_handler;
+	}
+#endif
+
+	WARN_ON(!update_irq_entry(irq_entry));
+	spin_unlock_irqrestore(&irq_lock, flags);
+
+	return 0;
+out_unlock:
+	spin_unlock_irqrestore(&irq_lock, flags);
+out:
+	return err;
+}
+
+/*
+ * Remove the entry or entries for a specific FD, if you
+ * don't want to remove all the possible entries then use
+ * um_free_irq() or deactivate_fd() instead.
+ */
+void free_irq_by_fd(int fd)
+{
+	struct irq_entry *to_free;
+	unsigned long flags;
+
+	spin_lock_irqsave(&irq_lock, flags);
+	to_free = get_irq_entry_by_fd(fd);
+	free_irq_entry(to_free, true);
+	spin_unlock_irqrestore(&irq_lock, flags);
+}
+EXPORT_SYMBOL(free_irq_by_fd);
+
+static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
+{
+	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 i;
+
+		for (i = 0; i < NUM_IRQ_TYPES; i++) {
+			struct irq_reg *reg = &entry->reg[i];
+
+			if (!reg->events)
+				continue;
+			if (reg->irq != irq)
+				continue;
+			if (reg->id != dev)
+				continue;
+
+			os_del_epoll_fd(entry->fd);
+			reg->events = 0;
+			update_or_free_irq_entry(entry);
+			goto out;
+		}
+	}
+out:
+	spin_unlock_irqrestore(&irq_lock, flags);
+}
+
+void deactivate_fd(int fd, int irqnum)
+{
+	struct irq_entry *entry;
+	unsigned long flags;
+	enum um_irq_type i;
+
+	os_del_epoll_fd(fd);
+
+	spin_lock_irqsave(&irq_lock, flags);
+	entry = get_irq_entry_by_fd(fd);
+	if (!entry)
+		goto out;
+
+	for (i = 0; i < NUM_IRQ_TYPES; i++) {
+		if (!entry->reg[i].events)
+			continue;
+		if (entry->reg[i].irq == irqnum)
+			entry->reg[i].events = 0;
+	}
+
+	update_or_free_irq_entry(entry);
+out:
+	spin_unlock_irqrestore(&irq_lock, flags);
+
+	ignore_sigio_fd(fd);
+}
+EXPORT_SYMBOL(deactivate_fd);
+
+/*
+ * Called just before shutdown in order to provide a clean exec
+ * environment in case the system is rebooting.  No locking because
+ * that would cause a pointless shutdown hang if something hadn't
+ * released the lock.
+ */
+int deactivate_all_fds(void)
+{
+	struct irq_entry *entry;
+
+	/* Stop IO. The IRQ loop has no lock so this is our
+	 * only way of making sure we are safe to dispose
+	 * of all IRQ handlers
+	 */
+	os_set_ioignore();
+
+	/* we can no longer call kfree() here so just deactivate */
+	list_for_each_entry(entry, &active_fds, list)
+		os_del_epoll_fd(entry->fd);
+	os_close_epoll_fd();
+	return 0;
+}
+
+/*
+ * do_IRQ handles all normal device IRQs (the special
+ * SMP cross-CPU interrupts have their own specific
+ * handlers).
+ */
+unsigned int do_IRQ(int irq, struct uml_pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs((struct pt_regs *)regs);
+	irq_enter();
+	generic_handle_irq(irq);
+	irq_exit();
+	set_irq_regs(old_regs);
+	return 1;
+}
+
+void um_free_irq(int irq, void *dev)
+{
+	if (WARN(irq < 0 || irq > UM_LAST_SIGNAL_IRQ,
+		 "freeing invalid irq %d", irq))
+		return;
+
+	free_irq_by_irq_and_dev(irq, dev);
+	free_irq(irq, dev);
+	clear_bit(irq, irqs_allocated);
+}
+EXPORT_SYMBOL(um_free_irq);
+
+static int
+_um_request_irq(int irq, int fd, enum um_irq_type type,
+		irq_handler_t handler, unsigned long irqflags,
+		const char *devname, void *dev_id,
+		void (*timetravel_handler)(int, int, void *,
+					   struct time_travel_event *))
+{
+	int err;
+
+	if (irq == UM_IRQ_ALLOC) {
+		int i;
+
+		for (i = UM_FIRST_DYN_IRQ; i < NR_IRQS; i++) {
+			if (!test_and_set_bit(i, irqs_allocated)) {
+				irq = i;
+				break;
+			}
+		}
+	}
+
+	if (irq < 0)
+		return -ENOSPC;
+
+	if (fd != -1) {
+		err = activate_fd(irq, fd, type, dev_id, timetravel_handler);
+		if (err)
+			goto error;
+	}
+
+	err = request_irq(irq, handler, irqflags, devname, dev_id);
+	if (err < 0)
+		goto error;
+
+	return irq;
+error:
+	clear_bit(irq, irqs_allocated);
+	return err;
+}
+
+int um_request_irq(int irq, int fd, enum um_irq_type type,
+		   irq_handler_t handler, unsigned long irqflags,
+		   const char *devname, void *dev_id)
+{
+	return _um_request_irq(irq, fd, type, handler, irqflags,
+			       devname, dev_id, NULL);
+}
+EXPORT_SYMBOL(um_request_irq);
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+int um_request_irq_tt(int irq, int fd, enum um_irq_type type,
+		      irq_handler_t handler, unsigned long irqflags,
+		      const char *devname, void *dev_id,
+		      void (*timetravel_handler)(int, int, void *,
+						 struct time_travel_event *))
+{
+	return _um_request_irq(irq, fd, type, handler, irqflags,
+			       devname, dev_id, timetravel_handler);
+}
+EXPORT_SYMBOL(um_request_irq_tt);
+
+void sigio_run_timetravel_handlers(void)
+{
+	_sigio_handler(NULL, true);
+}
+#endif
+
+#ifdef CONFIG_PM_SLEEP
+void um_irqs_suspend(void)
+{
+	struct irq_entry *entry;
+	unsigned long flags;
+
+	irqs_suspended = true;
+
+	spin_lock_irqsave(&irq_lock, flags);
+	list_for_each_entry(entry, &active_fds, list) {
+		enum um_irq_type t;
+		bool clear = true;
+
+		for (t = 0; t < NUM_IRQ_TYPES; t++) {
+			if (!entry->reg[t].events)
+				continue;
+
+			/*
+			 * For the SIGIO_WRITE_IRQ, which is used to handle the
+			 * SIGIO workaround thread, we need special handling:
+			 * enable wake for it itself, but below we tell it about
+			 * any FDs that should be suspended.
+			 */
+			if (entry->reg[t].wakeup ||
+			    entry->reg[t].irq == SIGIO_WRITE_IRQ
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+			    || entry->reg[t].timetravel_handler
+#endif
+			    ) {
+				clear = false;
+				break;
+			}
+		}
+
+		if (clear) {
+			entry->suspended = true;
+			os_clear_fd_async(entry->fd);
+			entry->sigio_workaround =
+				!__ignore_sigio_fd(entry->fd);
+		}
+	}
+	spin_unlock_irqrestore(&irq_lock, flags);
+}
+
+void um_irqs_resume(void)
+{
+	struct irq_entry *entry;
+	unsigned long flags;
+
+
+	local_irq_save(flags);
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+	/*
+	 * We don't need to lock anything here since we're in resume
+	 * and nothing else is running, but have disabled IRQs so we
+	 * don't try anything else with the interrupt list from there.
+	 */
+	list_for_each_entry(entry, &active_fds, list) {
+		enum um_irq_type t;
+
+		for (t = 0; t < NUM_IRQ_TYPES; t++) {
+			struct irq_reg *reg = &entry->reg[t];
+
+			if (reg->pending_on_resume) {
+				irq_enter();
+				generic_handle_irq(reg->irq);
+				irq_exit();
+				reg->pending_on_resume = false;
+			}
+		}
+	}
+#endif
+
+	spin_lock(&irq_lock);
+	list_for_each_entry(entry, &active_fds, list) {
+		if (entry->suspended) {
+			int err = os_set_fd_async(entry->fd);
+
+			WARN(err < 0, "os_set_fd_async returned %d\n", err);
+			entry->suspended = false;
+
+			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 < UM_LAST_SIGNAL_IRQ; 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;
+}
+