From 76cb841cb886eef6b3bee341a2266c76578724ad Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Mon, 6 May 2024 03:02:30 +0200 Subject: Adding upstream version 4.19.249. Signed-off-by: Daniel Baumann --- arch/um/kernel/irq.c | 609 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 609 insertions(+) create mode 100644 arch/um/kernel/irq.c (limited to 'arch/um/kernel/irq.c') diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c new file mode 100644 index 000000000..2753718d3 --- /dev/null +++ b/arch/um/kernel/irq.c @@ -0,0 +1,609 @@ +/* + * Copyright (C) 2017 - Cambridge Greys Ltd + * Copyright (C) 2011 - 2014 Cisco Systems Inc + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +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_fd array for each fd - + * one entry per IRQ type + */ + +struct irq_entry { + struct irq_entry *next; + int fd; + struct irq_fd *irq_array[MAX_IRQ_TYPE + 1]; +}; + +static struct irq_entry *active_fds; + +static DEFINE_SPINLOCK(irq_lock); + +static void irq_io_loop(struct irq_fd *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->purge)); + if (!irq->purge) + irq->active = true; + } else { + irq->pending = true; + } +} + +void sigio_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs) +{ + struct irq_entry *irq_entry; + struct irq_fd *irq; + + int n, i, j; + + 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++) { + /* Epoll back reference is the entry with 3 irq_fd + * leaves - one for each irq type. + */ + irq_entry = (struct irq_entry *) + os_epoll_get_data_pointer(i); + for (j = 0; j < MAX_IRQ_TYPE ; j++) { + irq = irq_entry->irq_array[j]; + if (irq == NULL) + continue; + if (os_epoll_triggered(i, irq->events) > 0) + irq_io_loop(irq, regs); + if (irq->purge) { + irq_entry->irq_array[j] = NULL; + kfree(irq); + } + } + } + } + + free_irqs(); +} + +static int assign_epoll_events_to_irq(struct irq_entry *irq_entry) +{ + int i; + int events = 0; + struct irq_fd *irq; + + for (i = 0; i < MAX_IRQ_TYPE ; i++) { + irq = irq_entry->irq_array[i]; + if (irq != NULL) + events = irq->events | events; + } + if (events > 0) { + /* os_add_epoll will call os_mod_epoll if this already exists */ + return os_add_epoll_fd(events, irq_entry->fd, irq_entry); + } + /* No events - delete */ + return os_del_epoll_fd(irq_entry->fd); +} + + + +static int activate_fd(int irq, int fd, int type, void *dev_id) +{ + struct irq_fd *new_fd; + struct irq_entry *irq_entry; + int i, err, events; + unsigned long flags; + + err = os_set_fd_async(fd); + if (err < 0) + goto out; + + spin_lock_irqsave(&irq_lock, flags); + + /* Check if we have an entry for this fd */ + + err = -EBUSY; + for (irq_entry = active_fds; + irq_entry != NULL; irq_entry = irq_entry->next) { + if (irq_entry->fd == fd) + break; + } + + if (irq_entry == NULL) { + /* This needs to be atomic as it may be called from an + * IRQ context. + */ + irq_entry = kmalloc(sizeof(struct irq_entry), GFP_ATOMIC); + if (irq_entry == NULL) { + printk(KERN_ERR + "Failed to allocate new IRQ entry\n"); + goto out_unlock; + } + irq_entry->fd = fd; + for (i = 0; i < MAX_IRQ_TYPE; i++) + irq_entry->irq_array[i] = NULL; + irq_entry->next = active_fds; + active_fds = irq_entry; + } + + /* Check if we are trying to re-register an interrupt for a + * particular fd + */ + + if (irq_entry->irq_array[type] != NULL) { + printk(KERN_ERR + "Trying to reregister IRQ %d FD %d TYPE %d ID %p\n", + irq, fd, type, dev_id + ); + goto out_unlock; + } else { + /* New entry for this fd */ + + err = -ENOMEM; + new_fd = kmalloc(sizeof(struct irq_fd), GFP_ATOMIC); + if (new_fd == NULL) + goto out_unlock; + + events = os_event_mask(type); + + *new_fd = ((struct irq_fd) { + .id = dev_id, + .irq = irq, + .type = type, + .events = events, + .active = true, + .pending = false, + .purge = false + }); + /* Turn off any IO on this fd - allows us to + * avoid locking the IRQ loop + */ + os_del_epoll_fd(irq_entry->fd); + irq_entry->irq_array[type] = new_fd; + } + + /* Turn back IO on with the correct (new) IO event mask */ + assign_epoll_events_to_irq(irq_entry); + spin_unlock_irqrestore(&irq_lock, flags); + maybe_sigio_broken(fd, (type != IRQ_NONE)); + + return 0; +out_unlock: + spin_unlock_irqrestore(&irq_lock, flags); +out: + return err; +} + +/* + * Walk the IRQ list and dispose of any unused entries. + * Should be done under irq_lock. + */ + +static void garbage_collect_irq_entries(void) +{ + int i; + bool reap; + struct irq_entry *walk; + struct irq_entry *previous = NULL; + struct irq_entry *to_free; + + if (active_fds == NULL) + return; + walk = active_fds; + while (walk != NULL) { + reap = true; + for (i = 0; i < MAX_IRQ_TYPE ; i++) { + if (walk->irq_array[i] != NULL) { + reap = false; + break; + } + } + if (reap) { + if (previous == NULL) + active_fds = walk->next; + else + previous->next = walk->next; + to_free = walk; + } else { + to_free = NULL; + } + walk = walk->next; + if (to_free != NULL) + kfree(to_free); + } +} + +/* + * Walk the IRQ list and get the descriptor for our FD + */ + +static struct irq_entry *get_irq_entry_by_fd(int fd) +{ + struct irq_entry *walk = active_fds; + + while (walk != NULL) { + if (walk->fd == fd) + return walk; + walk = walk->next; + } + return NULL; +} + + +/* + * Walk the IRQ list and dispose of an entry for a specific + * device, fd and number. Note - if sharing an IRQ for read + * and writefor the same FD it will be disposed in either case. + * If this behaviour is undesirable use different IRQ ids. + */ + +#define IGNORE_IRQ 1 +#define IGNORE_DEV (1<<1) + +static void do_free_by_irq_and_dev( + struct irq_entry *irq_entry, + unsigned int irq, + void *dev, + int flags +) +{ + int i; + struct irq_fd *to_free; + + for (i = 0; i < MAX_IRQ_TYPE ; i++) { + if (irq_entry->irq_array[i] != NULL) { + if ( + ((flags & IGNORE_IRQ) || + (irq_entry->irq_array[i]->irq == irq)) && + ((flags & IGNORE_DEV) || + (irq_entry->irq_array[i]->id == dev)) + ) { + /* Turn off any IO on this fd - allows us to + * avoid locking the IRQ loop + */ + os_del_epoll_fd(irq_entry->fd); + to_free = irq_entry->irq_array[i]; + irq_entry->irq_array[i] = NULL; + assign_epoll_events_to_irq(irq_entry); + if (to_free->active) + to_free->purge = true; + else + kfree(to_free); + } + } + } +} + +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); + if (to_free != NULL) { + do_free_by_irq_and_dev( + to_free, + -1, + NULL, + IGNORE_IRQ | IGNORE_DEV + ); + } + garbage_collect_irq_entries(); + 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 *to_free; + unsigned long flags; + + spin_lock_irqsave(&irq_lock, flags); + to_free = active_fds; + while (to_free != NULL) { + do_free_by_irq_and_dev( + to_free, + irq, + dev, + 0 + ); + to_free = to_free->next; + } + garbage_collect_irq_entries(); + spin_unlock_irqrestore(&irq_lock, flags); +} + + +void reactivate_fd(int fd, int irqnum) +{ + /** NOP - we do auto-EOI now **/ +} + +void deactivate_fd(int fd, int irqnum) +{ + struct irq_entry *to_free; + unsigned long flags; + + os_del_epoll_fd(fd); + spin_lock_irqsave(&irq_lock, flags); + to_free = get_irq_entry_by_fd(fd); + if (to_free != NULL) { + do_free_by_irq_and_dev( + to_free, + irqnum, + NULL, + IGNORE_DEV + ); + } + garbage_collect_irq_entries(); + 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) +{ + unsigned long flags; + struct irq_entry *to_free; + + spin_lock_irqsave(&irq_lock, flags); + /* 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(); + to_free = active_fds; + while (to_free != NULL) { + do_free_by_irq_and_dev( + to_free, + -1, + NULL, + IGNORE_IRQ | IGNORE_DEV + ); + to_free = to_free->next; + } + garbage_collect_irq_entries(); + spin_unlock_irqrestore(&irq_lock, flags); + 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(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); + /* 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; +} + -- cgit v1.2.3