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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /arch/um/kernel/irq.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/um/kernel/irq.c')
-rw-r--r-- | arch/um/kernel/irq.c | 766 |
1 files changed, 766 insertions, 0 deletions
diff --git a/arch/um/kernel/irq.c b/arch/um/kernel/irq.c new file mode 100644 index 0000000000..635d44606b --- /dev/null +++ b/arch/um/kernel/irq.c @@ -0,0 +1,766 @@ +// 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> + + +/* 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, ®->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; +} + |