- 根目录:
- arch
- um
- kernel
- irq.c
/*
* 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 siginfo *unused_si, struct uml_pt_regs *regs)
{
struct irq_fd *irq_fd;
int n;
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;
}
void um_free_irq(unsigned int irq, void *dev)
{
free_irq_by_irq_and_dev(irq, dev);
free_irq(irq, dev);
}
EXPORT_SYMBOL(um_free_irq);
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",
.irq_disable = dummy,
.irq_enable = dummy,
.irq_ack = dummy,
.irq_mask = dummy,
.irq_unmask = dummy,
};
static struct irq_chip SIGVTALRM_irq_type = {
.name = "SIGVTALRM",
.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, &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;
}