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authorAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
committerAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /arch/um/kernel/irq.c
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
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fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'arch/um/kernel/irq.c')
-rw-r--r--arch/um/kernel/irq.c464
1 files changed, 464 insertions, 0 deletions
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c
new file mode 100644
index 00000000000..71b8c947e5e
--- /dev/null
+++ b/arch/um/kernel/irq.c
@@ -0,0 +1,464 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ * 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"
+
+/*
+ * This list is accessed under irq_lock, except in sigio_handler,
+ * where it is safe from being modified. IRQ handlers won't change it -
+ * if an IRQ source has vanished, it will be freed by free_irqs just
+ * before returning from sigio_handler. That will process a separate
+ * list of irqs to free, with its own locking, coming back here to
+ * remove list elements, taking the irq_lock to do so.
+ */
+static struct irq_fd *active_fds = NULL;
+static struct irq_fd **last_irq_ptr = &active_fds;
+
+extern void free_irqs(void);
+
+void sigio_handler(int sig, struct uml_pt_regs *regs)
+{
+ struct irq_fd *irq_fd;
+ int n;
+
+ if (smp_sigio_handler())
+ return;
+
+ while (1) {
+ n = os_waiting_for_events(active_fds);
+ if (n <= 0) {
+ if (n == -EINTR)
+ continue;
+ else break;
+ }
+
+ for (irq_fd = active_fds; irq_fd != NULL;
+ irq_fd = irq_fd->next) {
+ if (irq_fd->current_events != 0) {
+ irq_fd->current_events = 0;
+ do_IRQ(irq_fd->irq, regs);
+ }
+ }
+ }
+
+ free_irqs();
+}
+
+static DEFINE_SPINLOCK(irq_lock);
+
+static int activate_fd(int irq, int fd, int type, void *dev_id)
+{
+ struct pollfd *tmp_pfd;
+ struct irq_fd *new_fd, *irq_fd;
+ unsigned long flags;
+ int events, err, n;
+
+ err = os_set_fd_async(fd);
+ if (err < 0)
+ goto out;
+
+ err = -ENOMEM;
+ new_fd = kmalloc(sizeof(struct irq_fd), GFP_KERNEL);
+ if (new_fd == NULL)
+ goto out;
+
+ if (type == IRQ_READ)
+ events = UM_POLLIN | UM_POLLPRI;
+ else events = UM_POLLOUT;
+ *new_fd = ((struct irq_fd) { .next = NULL,
+ .id = dev_id,
+ .fd = fd,
+ .type = type,
+ .irq = irq,
+ .events = events,
+ .current_events = 0 } );
+
+ err = -EBUSY;
+ spin_lock_irqsave(&irq_lock, flags);
+ for (irq_fd = active_fds; irq_fd != NULL; irq_fd = irq_fd->next) {
+ if ((irq_fd->fd == fd) && (irq_fd->type == type)) {
+ printk(KERN_ERR "Registering fd %d twice\n", fd);
+ printk(KERN_ERR "Irqs : %d, %d\n", irq_fd->irq, irq);
+ printk(KERN_ERR "Ids : 0x%p, 0x%p\n", irq_fd->id,
+ dev_id);
+ goto out_unlock;
+ }
+ }
+
+ if (type == IRQ_WRITE)
+ fd = -1;
+
+ tmp_pfd = NULL;
+ n = 0;
+
+ while (1) {
+ n = os_create_pollfd(fd, events, tmp_pfd, n);
+ if (n == 0)
+ break;
+
+ /*
+ * n > 0
+ * It means we couldn't put new pollfd to current pollfds
+ * and tmp_fds is NULL or too small for new pollfds array.
+ * Needed size is equal to n as minimum.
+ *
+ * Here we have to drop the lock in order to call
+ * kmalloc, which might sleep.
+ * If something else came in and changed the pollfds array
+ * so we will not be able to put new pollfd struct to pollfds
+ * then we free the buffer tmp_fds and try again.
+ */
+ spin_unlock_irqrestore(&irq_lock, flags);
+ kfree(tmp_pfd);
+
+ tmp_pfd = kmalloc(n, GFP_KERNEL);
+ if (tmp_pfd == NULL)
+ goto out_kfree;
+
+ spin_lock_irqsave(&irq_lock, flags);
+ }
+
+ *last_irq_ptr = new_fd;
+ last_irq_ptr = &new_fd->next;
+
+ spin_unlock_irqrestore(&irq_lock, flags);
+
+ /*
+ * This calls activate_fd, so it has to be outside the critical
+ * section.
+ */
+ maybe_sigio_broken(fd, (type == IRQ_READ));
+
+ return 0;
+
+ out_unlock:
+ spin_unlock_irqrestore(&irq_lock, flags);
+ out_kfree:
+ kfree(new_fd);
+ out:
+ return err;
+}
+
+static void free_irq_by_cb(int (*test)(struct irq_fd *, void *), void *arg)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&irq_lock, flags);
+ os_free_irq_by_cb(test, arg, active_fds, &last_irq_ptr);
+ spin_unlock_irqrestore(&irq_lock, flags);
+}
+
+struct irq_and_dev {
+ int irq;
+ void *dev;
+};
+
+static int same_irq_and_dev(struct irq_fd *irq, void *d)
+{
+ struct irq_and_dev *data = d;
+
+ return ((irq->irq == data->irq) && (irq->id == data->dev));
+}
+
+static void free_irq_by_irq_and_dev(unsigned int irq, void *dev)
+{
+ struct irq_and_dev data = ((struct irq_and_dev) { .irq = irq,
+ .dev = dev });
+
+ free_irq_by_cb(same_irq_and_dev, &data);
+}
+
+static int same_fd(struct irq_fd *irq, void *fd)
+{
+ return (irq->fd == *((int *)fd));
+}
+
+void free_irq_by_fd(int fd)
+{
+ free_irq_by_cb(same_fd, &fd);
+}
+
+/* Must be called with irq_lock held */
+static struct irq_fd *find_irq_by_fd(int fd, int irqnum, int *index_out)
+{
+ struct irq_fd *irq;
+ int i = 0;
+ int fdi;
+
+ for (irq = active_fds; irq != NULL; irq = irq->next) {
+ if ((irq->fd == fd) && (irq->irq == irqnum))
+ break;
+ i++;
+ }
+ if (irq == NULL) {
+ printk(KERN_ERR "find_irq_by_fd doesn't have descriptor %d\n",
+ fd);
+ goto out;
+ }
+ fdi = os_get_pollfd(i);
+ if ((fdi != -1) && (fdi != fd)) {
+ printk(KERN_ERR "find_irq_by_fd - mismatch between active_fds "
+ "and pollfds, fd %d vs %d, need %d\n", irq->fd,
+ fdi, fd);
+ irq = NULL;
+ goto out;
+ }
+ *index_out = i;
+ out:
+ return irq;
+}
+
+void reactivate_fd(int fd, int irqnum)
+{
+ struct irq_fd *irq;
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&irq_lock, flags);
+ irq = find_irq_by_fd(fd, irqnum, &i);
+ if (irq == NULL) {
+ spin_unlock_irqrestore(&irq_lock, flags);
+ return;
+ }
+ os_set_pollfd(i, irq->fd);
+ spin_unlock_irqrestore(&irq_lock, flags);
+
+ add_sigio_fd(fd);
+}
+
+void deactivate_fd(int fd, int irqnum)
+{
+ struct irq_fd *irq;
+ unsigned long flags;
+ int i;
+
+ spin_lock_irqsave(&irq_lock, flags);
+ irq = find_irq_by_fd(fd, irqnum, &i);
+ if (irq == NULL) {
+ spin_unlock_irqrestore(&irq_lock, flags);
+ return;
+ }
+
+ os_set_pollfd(i, -1);
+ 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_fd *irq;
+ int err;
+
+ for (irq = active_fds; irq != NULL; irq = irq->next) {
+ err = os_clear_fd_async(irq->fd);
+ if (err)
+ return err;
+ }
+ /* If there is a signal already queued, after unblocking ignore it */
+ os_set_ioignore();
+
+ 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;
+}
+
+int um_request_irq(unsigned int irq, int fd, int type,
+ irq_handler_t handler,
+ unsigned long irqflags, const char * devname,
+ void *dev_id)
+{
+ int err;
+
+ if (fd != -1) {
+ err = activate_fd(irq, fd, type, dev_id);
+ if (err)
+ return err;
+ }
+
+ return request_irq(irq, handler, irqflags, devname, dev_id);
+}
+
+EXPORT_SYMBOL(um_request_irq);
+EXPORT_SYMBOL(reactivate_fd);
+
+/*
+ * 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 else than the timer. */
+static struct irq_chip normal_irq_type = {
+ .name = "SIGIO",
+ .release = free_irq_by_irq_and_dev,
+ .irq_disable = dummy,
+ .irq_enable = dummy,
+ .irq_ack = dummy,
+};
+
+static struct irq_chip SIGVTALRM_irq_type = {
+ .name = "SIGVTALRM",
+ .release = free_irq_by_irq_and_dev,
+ .irq_disable = dummy,
+ .irq_enable = dummy,
+ .irq_ack = dummy,
+};
+
+void __init init_IRQ(void)
+{
+ int i;
+
+ irq_set_chip_and_handler(TIMER_IRQ, &SIGVTALRM_irq_type, handle_edge_irq);
+
+ for (i = 1; i < NR_IRQS; i++)
+ irq_set_chip_and_handler(i, &normal_irq_type, handle_edge_irq);
+}
+
+/*
+ * 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;
+}
+