ntsync uses a misc device as the simplest and least intrusive uAPI interface.

Each file description on the device represents an isolated NT instance, intended to correspond to a single NT virtual machine.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/Kconfig | 9 ++++++++ drivers/misc/Makefile | 1 + drivers/misc/ntsync.c | 52 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 62 insertions(+) create mode 100644 drivers/misc/ntsync.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 4fb291f0bf7c..bdd8a71bd853 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -504,6 +504,15 @@ config OPEN_DICE measured boot flow. Userspace can use CDIs for remote attestation and sealing.

+config NTSYNC + tristate "NT synchronization primitive emulation" + help + This module provides kernel support for emulation of Windows NT + synchronization primitives. It is not a hardware driver. + + To compile this driver as a module, choose M here: the + module will be called ntsync. + If unsure, say N.

config VCPU_STALL_DETECTOR diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index ea6ea5bbbc9c..153a3f4837e8 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -59,6 +59,7 @@ obj-$(CONFIG_PVPANIC) += pvpanic/ obj-$(CONFIG_UACCE) += uacce/ obj-$(CONFIG_XILINX_SDFEC) += xilinx_sdfec.o obj-$(CONFIG_HISI_HIKEY_USB) += hisi_hikey_usb.o +obj-$(CONFIG_NTSYNC) += ntsync.o obj-$(CONFIG_HI6421V600_IRQ) += hi6421v600-irq.o obj-$(CONFIG_OPEN_DICE) += open-dice.o obj-$(CONFIG_GP_PCI1XXXX) += mchp_pci1xxxx/ diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c new file mode 100644 index 000000000000..e4969ef90722 --- /dev/null +++ b/drivers/misc/ntsync.c @@ -0,0 +1,52 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ntsync.c - Kernel driver for NT synchronization primitives + * + * Copyright (C) 2024 Elizabeth Figura + */ + +#include <linux/fs.h> +#include <linux/miscdevice.h> +#include <linux/module.h> + +#define NTSYNC_NAME "ntsync" + +static int ntsync_char_open(struct inode *inode, struct file *file) +{ + return nonseekable_open(inode, file); +} + +static int ntsync_char_release(struct inode *inode, struct file *file) +{ + return 0; +} + +static long ntsync_char_ioctl(struct file *file, unsigned int cmd, + unsigned long parm) +{ + switch (cmd) { + default: + return -ENOIOCTLCMD; + } +} + +static const struct file_operations ntsync_fops = { + .owner = THIS_MODULE, + .open = ntsync_char_open, + .release = ntsync_char_release, + .unlocked_ioctl = ntsync_char_ioctl, + .compat_ioctl = compat_ptr_ioctl, + .llseek = no_llseek, +}; + +static struct miscdevice ntsync_misc = { + .minor = MISC_DYNAMIC_MINOR, + .name = NTSYNC_NAME, + .fops = &ntsync_fops, +}; + +module_misc_device(ntsync_misc); + +MODULE_AUTHOR("Elizabeth Figura"); +MODULE_DESCRIPTION("Kernel driver for NT synchronization primitives"); +MODULE_LICENSE("GPL");

This corresponds to the NT syscall NtReleaseSemaphore().

This increases the semaphore's internal counter by the given value, and returns the previous value. If the counter would overflow the defined maximum, the function instead fails and returns -EOVERFLOW.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 68 +++++++++++++++++++++++++++++++++++-- include/uapi/linux/ntsync.h | 2 ++ 2 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 3ad86d98b82d..1af38969f9a2 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -20,23 +20,68 @@ enum ntsync_type { };

struct ntsync_obj { + spinlock_t lock; + enum ntsync_type type;

+ struct file *file; + struct ntsync_device *dev; + + /* The following fields are protected by the object lock. */ union { struct { __u32 count; __u32 max; } sem; } u; - - struct file *file; - struct ntsync_device *dev; };

struct ntsync_device { struct file *file; };

+/* + * Actually change the semaphore state, returning -EOVERFLOW if it is made + * invalid. + */ +static int post_sem_state(struct ntsync_obj *sem, __u32 count) +{ + lockdep_assert_held(&sem->lock); + + if (sem->u.sem.count + count < sem->u.sem.count || + sem->u.sem.count + count > sem->u.sem.max) + return -EOVERFLOW; + + sem->u.sem.count += count; + return 0; +} + +static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp) +{ + __u32 __user *user_args = argp; + __u32 prev_count; + __u32 args; + int ret; + + if (copy_from_user(&args, argp, sizeof(args))) + return -EFAULT; + + if (sem->type != NTSYNC_TYPE_SEM) + return -EINVAL; + + spin_lock(&sem->lock); + + prev_count = sem->u.sem.count; + ret = post_sem_state(sem, args); + + spin_unlock(&sem->lock); + + if (!ret && put_user(prev_count, user_args)) + ret = -EFAULT; + + return ret; +} + static int ntsync_obj_release(struct inode *inode, struct file *file) { struct ntsync_obj *obj = file->private_data; @@ -47,9 +92,25 @@ static int ntsync_obj_release(struct inode *inode, struct file *file) return 0; }

+static long ntsync_obj_ioctl(struct file *file, unsigned int cmd, + unsigned long parm) +{ + struct ntsync_obj *obj = file->private_data; + void __user *argp = (void __user *)parm; + + switch (cmd) { + case NTSYNC_IOC_SEM_POST: + return ntsync_sem_post(obj, argp); + default: + return -ENOIOCTLCMD; + } +} + static const struct file_operations ntsync_obj_fops = { .owner = THIS_MODULE, .release = ntsync_obj_release, + .unlocked_ioctl = ntsync_obj_ioctl, + .compat_ioctl = compat_ptr_ioctl, .llseek = no_llseek, };

@@ -64,6 +125,7 @@ static struct ntsync_obj *ntsync_alloc_obj(struct ntsync_device *dev, obj->type = type; obj->dev = dev; get_file(dev->file); + spin_lock_init(&obj->lock);

return obj; } diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index f38818e7759d..878ec4f0f2e8 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -18,4 +18,6 @@ struct ntsync_sem_args {

#define NTSYNC_IOC_CREATE_SEM _IOWR('N', 0x80, struct ntsync_sem_args)

+#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32) + #endif

This is similar to NTSYNC_IOC_WAIT_ANY, but waits until all of the objects are simultaneously signaled, and then acquires all of them as a single atomic operation.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 244 ++++++++++++++++++++++++++++++++++-- include/uapi/linux/ntsync.h | 1 + 2 files changed, 237 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 0a0ab755d57f..b86d62094344 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -35,7 +35,34 @@ struct ntsync_obj { } sem; } u;

+ /* + * any_waiters is protected by the object lock, but all_waiters is + * protected by the device wait_all_lock. + */ struct list_head any_waiters; + struct list_head all_waiters; + + /* + * Hint describing how many tasks are queued on this object in a + * wait-all operation. + * + * Any time we do a wake, we may need to wake "all" waiters as well as + * "any" waiters. In order to atomically wake "all" waiters, we must + * lock all of the objects, and that means grabbing the wait_all_lock + * below (and, due to lock ordering rules, before locking this object). + * However, wait-all is a rare operation, and grabbing the wait-all + * lock for every wake would create unnecessary contention. + * Therefore we first check whether all_hint is zero, and, if it is, + * we skip trying to wake "all" waiters. + * + * This hint isn't protected by any lock. It might change during the + * course of a wake, but there's no meaningful race there; it's only a + * hint. + * + * Since wait requests must originate from user-space threads, we're + * limited here by PID_MAX_LIMIT, so there's no risk of overflow. + */ + atomic_t all_hint; };

struct ntsync_q_entry { @@ -56,14 +83,99 @@ struct ntsync_q { */ atomic_t signaled;

+ bool all; __u32 count; struct ntsync_q_entry entries[]; };

struct ntsync_device { + /* + * Wait-all operations must atomically grab all objects, and be totally + * ordered with respect to each other and wait-any operations. + * If one thread is trying to acquire several objects, another thread + * cannot touch the object at the same time. + * + * We achieve this by grabbing multiple object locks at the same time. + * However, this creates a lock ordering problem. To solve that problem, + * wait_all_lock is taken first whenever multiple objects must be locked + * at the same time. + */ + spinlock_t wait_all_lock; + struct file *file; };

+static bool is_signaled(struct ntsync_obj *obj, __u32 owner) +{ + lockdep_assert_held(&obj->lock); + + switch (obj->type) { + case NTSYNC_TYPE_SEM: + return !!obj->u.sem.count; + } + + WARN(1, "bad object type %#x\n", obj->type); + return false; +} + +/* + * "locked_obj" is an optional pointer to an object which is already locked and + * should not be locked again. This is necessary so that changing an object's + * state and waking it can be a single atomic operation. + */ +static void try_wake_all(struct ntsync_device *dev, struct ntsync_q *q, + struct ntsync_obj *locked_obj) +{ + __u32 count = q->count; + bool can_wake = true; + __u32 i; + + lockdep_assert_held(&dev->wait_all_lock); + if (locked_obj) + lockdep_assert_held(&locked_obj->lock); + + for (i = 0; i < count; i++) { + if (q->entries[i].obj != locked_obj) + spin_lock_nest_lock(&q->entries[i].obj->lock, &dev->wait_all_lock); + } + + for (i = 0; i < count; i++) { + if (!is_signaled(q->entries[i].obj, q->owner)) { + can_wake = false; + break; + } + } + + if (can_wake && atomic_cmpxchg(&q->signaled, -1, 0) == -1) { + for (i = 0; i < count; i++) { + struct ntsync_obj *obj = q->entries[i].obj; + + switch (obj->type) { + case NTSYNC_TYPE_SEM: + obj->u.sem.count--; + break; + } + } + wake_up_process(q->task); + } + + for (i = 0; i < count; i++) { + if (q->entries[i].obj != locked_obj) + spin_unlock(&q->entries[i].obj->lock); + } +} + +static void try_wake_all_obj(struct ntsync_device *dev, struct ntsync_obj *obj) +{ + struct ntsync_q_entry *entry; + + lockdep_assert_held(&dev->wait_all_lock); + lockdep_assert_held(&obj->lock); + + list_for_each_entry(entry, &obj->all_waiters, node) + try_wake_all(dev, entry->q, obj); +} + static void try_wake_any_sem(struct ntsync_obj *sem) { struct ntsync_q_entry *entry; @@ -101,6 +213,7 @@ static int post_sem_state(struct ntsync_obj *sem, __u32 count)

static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp) { + struct ntsync_device *dev = sem->dev; __u32 __user *user_args = argp; __u32 prev_count; __u32 args; @@ -112,14 +225,29 @@ static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp) if (sem->type != NTSYNC_TYPE_SEM) return -EINVAL;

- spin_lock(&sem->lock); + if (atomic_read(&sem->all_hint) > 0) { + spin_lock(&dev->wait_all_lock); + spin_lock_nest_lock(&sem->lock, &dev->wait_all_lock);

- prev_count = sem->u.sem.count; - ret = post_sem_state(sem, args); - if (!ret) - try_wake_any_sem(sem); + prev_count = sem->u.sem.count; + ret = post_sem_state(sem, args); + if (!ret) { + try_wake_all_obj(dev, sem); + try_wake_any_sem(sem); + }

- spin_unlock(&sem->lock); + spin_unlock(&sem->lock); + spin_unlock(&dev->wait_all_lock); + } else { + spin_lock(&sem->lock); + + prev_count = sem->u.sem.count; + ret = post_sem_state(sem, args); + if (!ret) + try_wake_any_sem(sem); + + spin_unlock(&sem->lock); + }

if (!ret && put_user(prev_count, user_args)) ret = -EFAULT; @@ -172,6 +300,8 @@ static struct ntsync_obj *ntsync_alloc_obj(struct ntsync_device *dev, get_file(dev->file); spin_lock_init(&obj->lock); INIT_LIST_HEAD(&obj->any_waiters); + INIT_LIST_HEAD(&obj->all_waiters); + atomic_set(&obj->all_hint, 0);

return obj; } @@ -274,7 +404,7 @@ static int ntsync_schedule(const struct ntsync_q *q, ktime_t *timeout) * Allocate and initialize the ntsync_q structure, but do not queue us yet. */ static int setup_wait(struct ntsync_device *dev, - const struct ntsync_wait_args *args, + const struct ntsync_wait_args *args, bool all, struct ntsync_q **ret_q) { const __u32 count = args->count; @@ -298,6 +428,7 @@ static int setup_wait(struct ntsync_device *dev, q->task = current; q->owner = args->owner; atomic_set(&q->signaled, -1); + q->all = all; q->count = count;

for (i = 0; i < count; i++) { @@ -307,6 +438,16 @@ static int setup_wait(struct ntsync_device *dev, if (!obj) goto err;

+ if (all) { + /* Check that the objects are all distinct. */ + for (j = 0; j < i; j++) { + if (obj == q->entries[j].obj) { + put_obj(obj); + goto err; + } + } + } + entry->obj = obj; entry->q = q; entry->index = i; @@ -343,7 +484,7 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp) if (copy_from_user(&args, argp, sizeof(args))) return -EFAULT;

- ret = setup_wait(dev, &args, &q); + ret = setup_wait(dev, &args, false, &q); if (ret < 0) return ret;

@@ -406,6 +547,89 @@ static int ntsync_wait_any(struct ntsync_device *dev, void __user *argp) return ret; }

+static int ntsync_wait_all(struct ntsync_device *dev, void __user *argp) +{ + struct ntsync_wait_args args; + struct ntsync_q *q; + ktime_t timeout; + int signaled; + __u32 i; + int ret; + + if (copy_from_user(&args, argp, sizeof(args))) + return -EFAULT; + + ret = setup_wait(dev, &args, true, &q); + if (ret < 0) + return ret; + + /* queue ourselves */ + + spin_lock(&dev->wait_all_lock); + + for (i = 0; i < args.count; i++) { + struct ntsync_q_entry *entry = &q->entries[i]; + struct ntsync_obj *obj = entry->obj; + + atomic_inc(&obj->all_hint); + + /* + * obj->all_waiters is protected by dev->wait_all_lock rather + * than obj->lock, so there is no need to acquire obj->lock + * here. + */ + list_add_tail(&entry->node, &obj->all_waiters); + } + + /* check if we are already signaled */ + + try_wake_all(dev, q, NULL); + + spin_unlock(&dev->wait_all_lock); + + /* sleep */ + + timeout = ns_to_ktime(args.timeout); + ret = ntsync_schedule(q, args.timeout == U64_MAX ? NULL : &timeout); + + /* and finally, unqueue */ + + spin_lock(&dev->wait_all_lock); + + for (i = 0; i < args.count; i++) { + struct ntsync_q_entry *entry = &q->entries[i]; + struct ntsync_obj *obj = entry->obj; + + /* + * obj->all_waiters is protected by dev->wait_all_lock rather + * than obj->lock, so there is no need to acquire it here. + */ + list_del(&entry->node); + + atomic_dec(&obj->all_hint); + + put_obj(obj); + } + + spin_unlock(&dev->wait_all_lock); + + signaled = atomic_read(&q->signaled); + if (signaled != -1) { + struct ntsync_wait_args __user *user_args = argp; + + /* even if we caught a signal, we need to communicate success */ + ret = 0; + + if (put_user(signaled, &user_args->index)) + ret = -EFAULT; + } else if (!ret) { + ret = -ETIMEDOUT; + } + + kfree(q); + return ret; +} + static int ntsync_char_open(struct inode *inode, struct file *file) { struct ntsync_device *dev; @@ -414,6 +638,8 @@ static int ntsync_char_open(struct inode *inode, struct file *file) if (!dev) return -ENOMEM;

+ spin_lock_init(&dev->wait_all_lock); + file->private_data = dev; dev->file = file; return nonseekable_open(inode, file); @@ -437,6 +663,8 @@ static long ntsync_char_ioctl(struct file *file, unsigned int cmd, switch (cmd) { case NTSYNC_IOC_CREATE_SEM: return ntsync_create_sem(dev, argp); + case NTSYNC_IOC_WAIT_ALL: + return ntsync_wait_all(dev, argp); case NTSYNC_IOC_WAIT_ANY: return ntsync_wait_any(dev, argp); default: diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index 9cd1dd05d971..524404f6aceb 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -29,6 +29,7 @@ struct ntsync_wait_args {

#define NTSYNC_IOC_CREATE_SEM _IOWR('N', 0x80, struct ntsync_sem_args) #define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args) +#define NTSYNC_IOC_WAIT_ALL _IOWR('N', 0x83, struct ntsync_wait_args)

#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32)

This corresponds to the NT syscall NtReleaseMutant().

This syscall decrements the mutex's recursion count by one, and returns the previous value. If the mutex is not owned by the given owner ID, the function instead fails and returns -EPERM.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 64 +++++++++++++++++++++++++++++++++++++ include/uapi/linux/ntsync.h | 1 + 2 files changed, 65 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 484219a266ae..1770ec4008af 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -290,6 +290,68 @@ static int ntsync_sem_post(struct ntsync_obj *sem, void __user *argp) return ret; }

+/* + * Actually change the mutex state, returning -EPERM if not the owner. + */ +static int unlock_mutex_state(struct ntsync_obj *mutex, + const struct ntsync_mutex_args *args) +{ + lockdep_assert_held(&mutex->lock); + + if (mutex->u.mutex.owner != args->owner) + return -EPERM; + + if (!--mutex->u.mutex.count) + mutex->u.mutex.owner = 0; + return 0; +} + +static int ntsync_mutex_unlock(struct ntsync_obj *mutex, void __user *argp) +{ + struct ntsync_mutex_args __user *user_args = argp; + struct ntsync_device *dev = mutex->dev; + struct ntsync_mutex_args args; + __u32 prev_count; + int ret; + + if (copy_from_user(&args, argp, sizeof(args))) + return -EFAULT; + if (!args.owner) + return -EINVAL; + + if (mutex->type != NTSYNC_TYPE_MUTEX) + return -EINVAL; + + if (atomic_read(&mutex->all_hint) > 0) { + spin_lock(&dev->wait_all_lock); + spin_lock_nest_lock(&mutex->lock, &dev->wait_all_lock); + + prev_count = mutex->u.mutex.count; + ret = unlock_mutex_state(mutex, &args); + if (!ret) { + try_wake_all_obj(dev, mutex); + try_wake_any_mutex(mutex); + } + + spin_unlock(&mutex->lock); + spin_unlock(&dev->wait_all_lock); + } else { + spin_lock(&mutex->lock); + + prev_count = mutex->u.mutex.count; + ret = unlock_mutex_state(mutex, &args); + if (!ret) + try_wake_any_mutex(mutex); + + spin_unlock(&mutex->lock); + } + + if (!ret && put_user(prev_count, &user_args->count)) + ret = -EFAULT; + + return ret; +} + static int ntsync_obj_release(struct inode *inode, struct file *file) { struct ntsync_obj *obj = file->private_data; @@ -309,6 +371,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd, switch (cmd) { case NTSYNC_IOC_SEM_POST: return ntsync_sem_post(obj, argp); + case NTSYNC_IOC_MUTEX_UNLOCK: + return ntsync_mutex_unlock(obj, argp); default: return -ENOIOCTLCMD; } diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index d68f24fd75a2..a3f5f4f13798 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -39,5 +39,6 @@ struct ntsync_wait_args { #define NTSYNC_IOC_CREATE_MUTEX _IOWR('N', 0x84, struct ntsync_sem_args)

#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32) +#define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)

#endif

This correspond to the NT syscall NtCreateEvent().

An NT event holds a single bit of state denoting whether it is signaled or unsignaled.

There are two types of events: manual-reset and automatic-reset. When an automatic-reset event is acquired via a wait function, its state is reset to unsignaled. Manual-reset events are not affected by wait functions.

Whether the event is manual-reset, and its initial state, are specified at creation time.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 60 +++++++++++++++++++++++++++++++++++++ include/uapi/linux/ntsync.h | 7 +++++ 2 files changed, 67 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index aadf01c65ca0..c719ddd9f6d7 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -18,6 +18,7 @@ enum ntsync_type { NTSYNC_TYPE_SEM, NTSYNC_TYPE_MUTEX, + NTSYNC_TYPE_EVENT, };

struct ntsync_obj { @@ -39,6 +40,10 @@ struct ntsync_obj { __u32 owner; bool ownerdead; } mutex; + struct { + bool manual; + bool signaled; + } event; } u;

/* @@ -123,6 +128,8 @@ static bool is_signaled(struct ntsync_obj *obj, __u32 owner) if (obj->u.mutex.owner && obj->u.mutex.owner != owner) return false; return obj->u.mutex.count < UINT_MAX; + case NTSYNC_TYPE_EVENT: + return obj->u.event.signaled; }

WARN(1, "bad object type %#x\n", obj->type); @@ -172,6 +179,10 @@ static void try_wake_all(struct ntsync_device *dev, struct ntsync_q *q, obj->u.mutex.count++; obj->u.mutex.owner = q->owner; break; + case NTSYNC_TYPE_EVENT: + if (!obj->u.event.manual) + obj->u.event.signaled = false; + break; } } wake_up_process(q->task); @@ -238,6 +249,26 @@ static void try_wake_any_mutex(struct ntsync_obj *mutex) } }

+static void try_wake_any_event(struct ntsync_obj *event) +{ + struct ntsync_q_entry *entry; + + lockdep_assert_held(&event->lock); + + list_for_each_entry(entry, &event->any_waiters, node) { + struct ntsync_q *q = entry->q; + + if (!event->u.event.signaled) + break; + + if (atomic_cmpxchg(&q->signaled, -1, entry->index) == -1) { + if (!event->u.event.manual) + event->u.event.signaled = false; + wake_up_process(q->task); + } + } +} + /* * Actually change the semaphore state, returning -EOVERFLOW if it is made * invalid. @@ -544,6 +575,30 @@ static int ntsync_create_mutex(struct ntsync_device *dev, void __user *argp) return put_user(fd, &user_args->mutex); }

+static int ntsync_create_event(struct ntsync_device *dev, void __user *argp) +{ + struct ntsync_event_args __user *user_args = argp; + struct ntsync_event_args args; + struct ntsync_obj *event; + int fd; + + if (copy_from_user(&args, argp, sizeof(args))) + return -EFAULT; + + event = ntsync_alloc_obj(dev, NTSYNC_TYPE_EVENT); + if (!event) + return -ENOMEM; + event->u.event.manual = args.manual; + event->u.event.signaled = args.signaled; + fd = ntsync_obj_get_fd(event); + if (fd < 0) { + kfree(event); + return fd; + } + + return put_user(fd, &user_args->event); +} + static struct ntsync_obj *get_obj(struct ntsync_device *dev, int fd) { struct file *file = fget(fd); @@ -665,6 +720,9 @@ static void try_wake_any_obj(struct ntsync_obj *obj) case NTSYNC_TYPE_MUTEX: try_wake_any_mutex(obj); break; + case NTSYNC_TYPE_EVENT: + try_wake_any_event(obj); + break; } }

@@ -857,6 +915,8 @@ static long ntsync_char_ioctl(struct file *file, unsigned int cmd, void __user *argp = (void __user *)parm;

switch (cmd) { + case NTSYNC_IOC_CREATE_EVENT: + return ntsync_create_event(dev, argp); case NTSYNC_IOC_CREATE_MUTEX: return ntsync_create_mutex(dev, argp); case NTSYNC_IOC_CREATE_SEM: diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index 3861397c6c2f..b8cf503365ef 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -22,6 +22,12 @@ struct ntsync_mutex_args { __u32 count; };

+struct ntsync_event_args { + __u32 event; + __u32 manual; + __u32 signaled; +}; + struct ntsync_wait_args { __u64 timeout; __u64 objs; @@ -37,6 +43,7 @@ struct ntsync_wait_args { #define NTSYNC_IOC_WAIT_ANY _IOWR('N', 0x82, struct ntsync_wait_args) #define NTSYNC_IOC_WAIT_ALL _IOWR('N', 0x83, struct ntsync_wait_args) #define NTSYNC_IOC_CREATE_MUTEX _IOWR('N', 0x84, struct ntsync_sem_args) +#define NTSYNC_IOC_CREATE_EVENT _IOWR('N', 0x87, struct ntsync_event_args)

#define NTSYNC_IOC_SEM_POST _IOWR('N', 0x81, __u32) #define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args)

This corresponds to the NT syscall NtResetEvent().

This sets the event to the unsignaled state, and returns its previous state.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 22 ++++++++++++++++++++++ include/uapi/linux/ntsync.h | 1 + 2 files changed, 23 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index b2da50989953..009d927739b8 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -482,6 +482,26 @@ static int ntsync_event_set(struct ntsync_obj *event, void __user *argp) return 0; }

+static int ntsync_event_reset(struct ntsync_obj *event, void __user *argp) +{ + __u32 prev_state; + + if (event->type != NTSYNC_TYPE_EVENT) + return -EINVAL; + + spin_lock(&event->lock); + + prev_state = event->u.event.signaled; + event->u.event.signaled = false; + + spin_unlock(&event->lock); + + if (put_user(prev_state, (__u32 __user *)argp)) + return -EFAULT; + + return 0; +} + static int ntsync_obj_release(struct inode *inode, struct file *file) { struct ntsync_obj *obj = file->private_data; @@ -507,6 +527,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd, return ntsync_mutex_kill(obj, argp); case NTSYNC_IOC_EVENT_SET: return ntsync_event_set(obj, argp); + case NTSYNC_IOC_EVENT_RESET: + return ntsync_event_reset(obj, argp); default: return -ENOIOCTLCMD; } diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index 782057552483..f2d7507d8438 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -49,5 +49,6 @@ struct ntsync_wait_args { #define NTSYNC_IOC_MUTEX_UNLOCK _IOWR('N', 0x85, struct ntsync_mutex_args) #define NTSYNC_IOC_MUTEX_KILL _IOW ('N', 0x86, __u32) #define NTSYNC_IOC_EVENT_SET _IOR ('N', 0x88, __u32) +#define NTSYNC_IOC_EVENT_RESET _IOR ('N', 0x89, __u32)

#endif

This corresponds to the NT syscall NtQuerySemaphore().

This returns the current count and maximum count of the semaphore.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 21 +++++++++++++++++++++ include/uapi/linux/ntsync.h | 1 + 2 files changed, 22 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 240ae858fa96..6dccfbfb2512 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -506,6 +506,25 @@ static int ntsync_event_reset(struct ntsync_obj *event, void __user *argp) return 0; }

+static int ntsync_sem_read(struct ntsync_obj *sem, void __user *argp) +{ + struct ntsync_sem_args __user *user_args = argp; + struct ntsync_sem_args args; + + if (sem->type != NTSYNC_TYPE_SEM) + return -EINVAL; + + args.sem = 0; + spin_lock(&sem->lock); + args.count = sem->u.sem.count; + args.max = sem->u.sem.max; + spin_unlock(&sem->lock); + + if (copy_to_user(user_args, &args, sizeof(args))) + return -EFAULT; + return 0; +} + static int ntsync_obj_release(struct inode *inode, struct file *file) { struct ntsync_obj *obj = file->private_data; @@ -525,6 +544,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd, switch (cmd) { case NTSYNC_IOC_SEM_POST: return ntsync_sem_post(obj, argp); + case NTSYNC_IOC_SEM_READ: + return ntsync_sem_read(obj, argp); case NTSYNC_IOC_MUTEX_UNLOCK: return ntsync_mutex_unlock(obj, argp); case NTSYNC_IOC_MUTEX_KILL: diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index 598f894f868d..6017f621687e 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -51,5 +51,6 @@ struct ntsync_wait_args { #define NTSYNC_IOC_EVENT_SET _IOR ('N', 0x88, __u32) #define NTSYNC_IOC_EVENT_RESET _IOR ('N', 0x89, __u32) #define NTSYNC_IOC_EVENT_PULSE _IOR ('N', 0x8a, __u32) +#define NTSYNC_IOC_SEM_READ _IOR ('N', 0x8b, struct ntsync_sem_args)

#endif

This corresponds to the NT syscall NtQueryEvent().

This returns the signaled state of the event and whether it is manual-reset.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- drivers/misc/ntsync.c | 21 +++++++++++++++++++++ include/uapi/linux/ntsync.h | 1 + 2 files changed, 22 insertions(+)

diff --git a/drivers/misc/ntsync.c b/drivers/misc/ntsync.c index 7f5f96ec7c69..5439c1c9e90f 100644 --- a/drivers/misc/ntsync.c +++ b/drivers/misc/ntsync.c @@ -546,6 +546,25 @@ static int ntsync_mutex_read(struct ntsync_obj *mutex, void __user *argp) return ret; }

+static int ntsync_event_read(struct ntsync_obj *event, void __user *argp) +{ + struct ntsync_event_args __user *user_args = argp; + struct ntsync_event_args args; + + if (event->type != NTSYNC_TYPE_EVENT) + return -EINVAL; + + args.event = 0; + spin_lock(&event->lock); + args.manual = event->u.event.manual; + args.signaled = event->u.event.signaled; + spin_unlock(&event->lock); + + if (copy_to_user(user_args, &args, sizeof(args))) + return -EFAULT; + return 0; +} + static int ntsync_obj_release(struct inode *inode, struct file *file) { struct ntsync_obj *obj = file->private_data; @@ -579,6 +598,8 @@ static long ntsync_obj_ioctl(struct file *file, unsigned int cmd, return ntsync_event_reset(obj, argp); case NTSYNC_IOC_EVENT_PULSE: return ntsync_event_set(obj, argp, true); + case NTSYNC_IOC_EVENT_READ: + return ntsync_event_read(obj, argp); default: return -ENOIOCTLCMD; } diff --git a/include/uapi/linux/ntsync.h b/include/uapi/linux/ntsync.h index a1d0ef581212..582d33b0dcac 100644 --- a/include/uapi/linux/ntsync.h +++ b/include/uapi/linux/ntsync.h @@ -53,5 +53,6 @@ struct ntsync_wait_args { #define NTSYNC_IOC_EVENT_PULSE _IOR ('N', 0x8a, __u32) #define NTSYNC_IOC_SEM_READ _IOR ('N', 0x8b, struct ntsync_sem_args) #define NTSYNC_IOC_MUTEX_READ _IOR ('N', 0x8c, struct ntsync_mutex_args) +#define NTSYNC_IOC_EVENT_READ _IOR ('N', 0x8d, struct ntsync_event_args)

#endif

Wine has tests for its synchronization primitives, but these are more accessible to kernel developers, and also allow us to test some edge cases that Wine does not care about.

This patch adds tests for semaphore-specific ioctls NTSYNC_IOC_SEM_POST and NTSYNC_IOC_SEM_READ, and waiting on semaphores.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- tools/testing/selftests/Makefile | 1 + .../testing/selftests/drivers/ntsync/Makefile | 8 + tools/testing/selftests/drivers/ntsync/config | 1 + .../testing/selftests/drivers/ntsync/ntsync.c | 143 ++++++++++++++++++ 4 files changed, 153 insertions(+) create mode 100644 tools/testing/selftests/drivers/ntsync/Makefile create mode 100644 tools/testing/selftests/drivers/ntsync/config create mode 100644 tools/testing/selftests/drivers/ntsync/ntsync.c

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 15b6a111c3be..6c714a4e6478 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -15,6 +15,7 @@ TARGETS += cpu-hotplug TARGETS += damon TARGETS += dmabuf-heaps TARGETS += drivers/dma-buf +TARGETS += drivers/ntsync TARGETS += drivers/s390x/uvdevice TARGETS += drivers/net/bonding TARGETS += drivers/net/team diff --git a/tools/testing/selftests/drivers/ntsync/Makefile b/tools/testing/selftests/drivers/ntsync/Makefile new file mode 100644 index 000000000000..a34da5ccacf0 --- /dev/null +++ b/tools/testing/selftests/drivers/ntsync/Makefile @@ -0,0 +1,8 @@ +# SPDX-LICENSE-IDENTIFIER: GPL-2.0-only +TEST_GEN_PROGS := ntsync + +top_srcdir =../../../../.. +CFLAGS += -I$(top_srcdir)/usr/include +LDLIBS += -lpthread + +include ../../lib.mk diff --git a/tools/testing/selftests/drivers/ntsync/config b/tools/testing/selftests/drivers/ntsync/config new file mode 100644 index 000000000000..60539c826d06 --- /dev/null +++ b/tools/testing/selftests/drivers/ntsync/config @@ -0,0 +1 @@ +CONFIG_WINESYNC=y diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c new file mode 100644 index 000000000000..6ceb48fb42e3 --- /dev/null +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Various unit tests for the "ntsync" synchronization primitive driver. + * + * Copyright (C) 2021-2022 Elizabeth Figura + */ + +#define _GNU_SOURCE +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <time.h> +#include <pthread.h> +#include <linux/ntsync.h> +#include "../../kselftest_harness.h" + +static int read_sem_state(int sem, __u32 *count, __u32 *max) +{ + struct ntsync_sem_args args; + int ret; + + memset(&args, 0xcc, sizeof(args)); + ret = ioctl(sem, NTSYNC_IOC_SEM_READ, &args); + *count = args.count; + *max = args.max; + return ret; +} + +#define check_sem_state(sem, count, max) \ + ({ \ + __u32 __count, __max; \ + int ret = read_sem_state((sem), &__count, &__max); \ + EXPECT_EQ(0, ret); \ + EXPECT_EQ((count), __count); \ + EXPECT_EQ((max), __max); \ + }) + +static int post_sem(int sem, __u32 *count) +{ + return ioctl(sem, NTSYNC_IOC_SEM_POST, count); +} + +static int wait_any(int fd, __u32 count, const int *objs, __u32 owner, __u32 *index) +{ + struct ntsync_wait_args args = {0}; + struct timespec timeout; + int ret; + + clock_gettime(CLOCK_MONOTONIC, &timeout); + + args.timeout = timeout.tv_sec * 1000000000 + timeout.tv_nsec; + args.count = count; + args.objs = (uintptr_t)objs; + args.owner = owner; + args.index = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_WAIT_ANY, &args); + *index = args.index; + return ret; +} + +TEST(semaphore_state) +{ + struct ntsync_sem_args sem_args; + struct timespec timeout; + __u32 count, index; + int fd, ret, sem; + + clock_gettime(CLOCK_MONOTONIC, &timeout); + + fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); + ASSERT_LE(0, fd); + + sem_args.count = 3; + sem_args.max = 2; + sem_args.sem = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args); + EXPECT_EQ(-1, ret); + EXPECT_EQ(EINVAL, errno); + + sem_args.count = 2; + sem_args.max = 2; + sem_args.sem = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, sem_args.sem); + sem = sem_args.sem; + check_sem_state(sem, 2, 2); + + count = 0; + ret = post_sem(sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(2, count); + check_sem_state(sem, 2, 2); + + count = 1; + ret = post_sem(sem, &count); + EXPECT_EQ(-1, ret); + EXPECT_EQ(EOVERFLOW, errno); + check_sem_state(sem, 2, 2); + + ret = wait_any(fd, 1, &sem, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem, 1, 2); + + ret = wait_any(fd, 1, &sem, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem, 0, 2); + + ret = wait_any(fd, 1, &sem, 123, &index); + EXPECT_EQ(-1, ret); + EXPECT_EQ(ETIMEDOUT, errno); + + count = 3; + ret = post_sem(sem, &count); + EXPECT_EQ(-1, ret); + EXPECT_EQ(EOVERFLOW, errno); + check_sem_state(sem, 0, 2); + + count = 2; + ret = post_sem(sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, count); + check_sem_state(sem, 2, 2); + + ret = wait_any(fd, 1, &sem, 123, &index); + EXPECT_EQ(0, ret); + ret = wait_any(fd, 1, &sem, 123, &index); + EXPECT_EQ(0, ret); + + count = 1; + ret = post_sem(sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, count); + check_sem_state(sem, 1, 2); + + close(sem); + + close(fd); +} + +TEST_HARNESS_MAIN

Test basic synchronous functionality of NTSYNC_IOC_WAIT_ANY, when objects are considered signaled or not signaled, and how they are affected by a successful wait.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- .../testing/selftests/drivers/ntsync/ntsync.c | 105 ++++++++++++++++++ 1 file changed, 105 insertions(+)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c index 80c8bd409d68..13e7c9d7441e 100644 --- a/tools/testing/selftests/drivers/ntsync/ntsync.c +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -321,4 +321,109 @@ TEST(mutex_state) close(fd); }

+TEST(test_wait_any) +{ + struct ntsync_mutex_args mutex_args = {0}; + struct ntsync_wait_args wait_args = {0}; + struct ntsync_sem_args sem_args = {0}; + __u32 owner, index, count; + struct timespec timeout; + int objs[2], fd, ret; + + clock_gettime(CLOCK_MONOTONIC, &timeout); + + fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); + ASSERT_LE(0, fd); + + sem_args.count = 2; + sem_args.max = 3; + sem_args.sem = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, sem_args.sem); + + mutex_args.owner = 0; + mutex_args.count = 0; + mutex_args.mutex = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_MUTEX, &mutex_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, mutex_args.mutex); + + objs[0] = sem_args.sem; + objs[1] = mutex_args.mutex; + + ret = wait_any(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem_args.sem, 1, 3); + check_mutex_state(mutex_args.mutex, 0, 0); + + ret = wait_any(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem_args.sem, 0, 3); + check_mutex_state(mutex_args.mutex, 0, 0); + + ret = wait_any(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, index); + check_sem_state(sem_args.sem, 0, 3); + check_mutex_state(mutex_args.mutex, 1, 123); + + count = 1; + ret = post_sem(sem_args.sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, count); + + ret = wait_any(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem_args.sem, 0, 3); + check_mutex_state(mutex_args.mutex, 1, 123); + + ret = wait_any(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, index); + check_sem_state(sem_args.sem, 0, 3); + check_mutex_state(mutex_args.mutex, 2, 123); + + ret = wait_any(fd, 2, objs, 456, &index); + EXPECT_EQ(-1, ret); + EXPECT_EQ(ETIMEDOUT, errno); + + owner = 123; + ret = ioctl(mutex_args.mutex, NTSYNC_IOC_MUTEX_KILL, &owner); + EXPECT_EQ(0, ret); + + ret = wait_any(fd, 2, objs, 456, &index); + EXPECT_EQ(-1, ret); + EXPECT_EQ(EOWNERDEAD, errno); + EXPECT_EQ(1, index); + + ret = wait_any(fd, 2, objs, 456, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, index); + + /* test waiting on the same object twice */ + count = 2; + ret = post_sem(sem_args.sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, count); + + objs[0] = objs[1] = sem_args.sem; + ret = wait_any(fd, 2, objs, 456, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, wait_args.index); + check_sem_state(sem_args.sem, 1, 3); + + ret = wait_any(fd, 0, NULL, 456, &index); + EXPECT_EQ(-1, ret); + EXPECT_EQ(ETIMEDOUT, errno); + + close(sem_args.sem); + close(mutex_args.mutex); + + close(fd); +} + TEST_HARNESS_MAIN

Test contended "wait-for-any" waits, to make sure that scheduling and wakeup logic works correctly.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- .../testing/selftests/drivers/ntsync/ntsync.c | 152 ++++++++++++++++++ 1 file changed, 152 insertions(+)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c index 77f1b7e42d76..96a866ef235f 100644 --- a/tools/testing/selftests/drivers/ntsync/ntsync.c +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -521,4 +521,156 @@ TEST(test_wait_all) close(fd); }

+struct wake_args +{ + int fd; + int obj; +}; + +struct wait_args +{ + int fd; + unsigned long request; + struct ntsync_wait_args *args; + int ret; + int err; +}; + +static void *wait_thread(void *arg) +{ + struct wait_args *args = arg; + + args->ret = ioctl(args->fd, args->request, args->args); + args->err = errno; + return NULL; +} + +static __u64 get_abs_timeout(unsigned int ms) +{ + struct timespec timeout; + clock_gettime(CLOCK_MONOTONIC, &timeout); + return (timeout.tv_sec * 1000000000) + timeout.tv_nsec + (ms * 1000000); +} + +static int wait_for_thread(pthread_t thread, unsigned int ms) +{ + struct timespec timeout; + + clock_gettime(CLOCK_REALTIME, &timeout); + timeout.tv_nsec += ms * 1000000; + timeout.tv_sec += (timeout.tv_nsec / 1000000000); + timeout.tv_nsec %= 1000000000; + return pthread_timedjoin_np(thread, NULL, &timeout); +} + +TEST(wake_any) +{ + struct ntsync_mutex_args mutex_args = {0}; + struct ntsync_wait_args wait_args = {0}; + struct ntsync_sem_args sem_args = {0}; + struct wait_args thread_args; + int objs[2], fd, ret; + __u32 count, index; + pthread_t thread; + + fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); + ASSERT_LE(0, fd); + + sem_args.count = 0; + sem_args.max = 3; + sem_args.sem = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_SEM, &sem_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, sem_args.sem); + + mutex_args.owner = 123; + mutex_args.count = 1; + mutex_args.mutex = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_MUTEX, &mutex_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, mutex_args.mutex); + + objs[0] = sem_args.sem; + objs[1] = mutex_args.mutex; + + /* test waking the semaphore */ + + wait_args.timeout = get_abs_timeout(1000); + wait_args.objs = (uintptr_t)objs; + wait_args.count = 2; + wait_args.owner = 456; + wait_args.index = 0xdeadbeef; + thread_args.fd = fd; + thread_args.args = &wait_args; + thread_args.request = NTSYNC_IOC_WAIT_ANY; + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + count = 1; + ret = post_sem(sem_args.sem, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, count); + check_sem_state(sem_args.sem, 0, 3); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(0, wait_args.index); + + /* test waking the mutex */ + + /* first grab it again for owner 123 */ + ret = wait_any(fd, 1, &mutex_args.mutex, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + + wait_args.timeout = get_abs_timeout(1000); + wait_args.owner = 456; + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = unlock_mutex(mutex_args.mutex, 123, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(2, count); + + ret = pthread_tryjoin_np(thread, NULL); + EXPECT_EQ(EBUSY, ret); + + ret = unlock_mutex(mutex_args.mutex, 123, &count); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, mutex_args.count); + check_mutex_state(mutex_args.mutex, 1, 456); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(1, wait_args.index); + + /* delete an object while it's being waited on */ + + wait_args.timeout = get_abs_timeout(200); + wait_args.owner = 123; + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + close(sem_args.sem); + close(mutex_args.mutex); + + ret = wait_for_thread(thread, 200); + EXPECT_EQ(0, ret); + EXPECT_EQ(-1, thread_args.ret); + EXPECT_EQ(ETIMEDOUT, thread_args.err); + + close(fd); +} + TEST_HARNESS_MAIN

Test event-specific ioctls NTSYNC_IOC_EVENT_SET, NTSYNC_IOC_EVENT_RESET, NTSYNC_IOC_EVENT_PULSE, NTSYNC_IOC_EVENT_READ for manual-reset events, and waiting on manual-reset events.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- .../testing/selftests/drivers/ntsync/ntsync.c | 89 +++++++++++++++++++ 1 file changed, 89 insertions(+)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c index 7776fe71b8ef..98fc70a9a58b 100644 --- a/tools/testing/selftests/drivers/ntsync/ntsync.c +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -73,6 +73,27 @@ static int unlock_mutex(int mutex, __u32 owner, __u32 *count) return ret; }

+static int read_event_state(int event, __u32 *signaled, __u32 *manual) +{ + struct ntsync_event_args args; + int ret; + + memset(&args, 0xcc, sizeof(args)); + ret = ioctl(event, NTSYNC_IOC_EVENT_READ, &args); + *signaled = args.signaled; + *manual = args.manual; + return ret; +} + +#define check_event_state(event, signaled, manual) \ + ({ \ + __u32 __signaled, __manual; \ + int ret = read_event_state((event), &__signaled, &__manual); \ + EXPECT_EQ(0, ret); \ + EXPECT_EQ((signaled), __signaled); \ + EXPECT_EQ((manual), __manual); \ + }) + static int wait_objs(int fd, unsigned long request, __u32 count, const int *objs, __u32 owner, __u32 *index) { @@ -332,6 +353,74 @@ TEST(mutex_state) close(fd); }

+TEST(manual_event_state) +{ + struct ntsync_event_args event_args; + __u32 index, signaled; + int fd, event, ret; + + fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); + ASSERT_LE(0, fd); + + event_args.manual = 1; + event_args.signaled = 0; + event_args.event = 0xdeadbeef; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &event_args); + EXPECT_EQ(0, ret); + EXPECT_NE(0xdeadbeef, event_args.event); + event = event_args.event; + check_event_state(event, 0, 1); + + signaled = 0xdeadbeef; + ret = ioctl(event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event, 1, 1); + + ret = ioctl(event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + check_event_state(event, 1, 1); + + ret = wait_any(fd, 1, &event, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_event_state(event, 1, 1); + + signaled = 0xdeadbeef; + ret = ioctl(event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + check_event_state(event, 0, 1); + + ret = ioctl(event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event, 0, 1); + + ret = wait_any(fd, 1, &event, 123, &index); + EXPECT_EQ(-1, ret); + EXPECT_EQ(ETIMEDOUT, errno); + + ret = ioctl(event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + + ret = ioctl(event, NTSYNC_IOC_EVENT_PULSE, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + check_event_state(event, 0, 1); + + ret = ioctl(event, NTSYNC_IOC_EVENT_PULSE, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event, 0, 1); + + close(event); + + close(fd); +} + TEST(test_wait_any) { struct ntsync_mutex_args mutex_args = {0};

Expand the contended wait tests, which previously only covered events and semaphores, to cover events as well.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- .../testing/selftests/drivers/ntsync/ntsync.c | 151 +++++++++++++++++- 1 file changed, 147 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c index f1fb28949367..598333df3e6d 100644 --- a/tools/testing/selftests/drivers/ntsync/ntsync.c +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -587,6 +587,7 @@ TEST(test_wait_any)

TEST(test_wait_all) { + struct ntsync_event_args event_args = {0}; struct ntsync_mutex_args mutex_args = {0}; struct ntsync_sem_args sem_args = {0}; __u32 owner, index, count; @@ -609,6 +610,11 @@ TEST(test_wait_all) EXPECT_EQ(0, ret); EXPECT_NE(0xdeadbeef, mutex_args.mutex);

+ event_args.manual = true; + event_args.signaled = true; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &event_args); + EXPECT_EQ(0, ret); + objs[0] = sem_args.sem; objs[1] = mutex_args.mutex;

@@ -657,6 +663,14 @@ TEST(test_wait_all) check_sem_state(sem_args.sem, 1, 3); check_mutex_state(mutex_args.mutex, 1, 123);

+ objs[0] = sem_args.sem; + objs[1] = event_args.event; + ret = wait_all(fd, 2, objs, 123, &index); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, index); + check_sem_state(sem_args.sem, 0, 3); + check_event_state(event_args.event, 1, 1); + /* test waiting on the same object twice */ objs[0] = objs[1] = sem_args.sem; ret = wait_all(fd, 2, objs, 123, &index); @@ -665,6 +679,7 @@ TEST(test_wait_all)

close(sem_args.sem); close(mutex_args.mutex); + close(event_args.event);

close(fd); } @@ -713,12 +728,13 @@ static int wait_for_thread(pthread_t thread, unsigned int ms)

TEST(wake_any) { + struct ntsync_event_args event_args = {0}; struct ntsync_mutex_args mutex_args = {0}; struct ntsync_wait_args wait_args = {0}; struct ntsync_sem_args sem_args = {0}; struct wait_args thread_args; + __u32 count, index, signaled; int objs[2], fd, ret; - __u32 count, index; pthread_t thread;

fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); @@ -800,10 +816,101 @@ TEST(wake_any) EXPECT_EQ(0, thread_args.ret); EXPECT_EQ(1, wait_args.index);

+ /* test waking events */ + + event_args.manual = false; + event_args.signaled = false; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &event_args); + EXPECT_EQ(0, ret); + + objs[1] = event_args.event; + wait_args.timeout = get_abs_timeout(1000); + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event_args.event, 0, 0); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(1, wait_args.index); + + wait_args.timeout = get_abs_timeout(1000); + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_PULSE, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event_args.event, 0, 0); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(1, wait_args.index); + + close(event_args.event); + + event_args.manual = true; + event_args.signaled = false; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &event_args); + EXPECT_EQ(0, ret); + + objs[1] = event_args.event; + wait_args.timeout = get_abs_timeout(1000); + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event_args.event, 1, 1); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(1, wait_args.index); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + + wait_args.timeout = get_abs_timeout(1000); + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_PULSE, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_event_state(event_args.event, 0, 1); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(1, wait_args.index); + + close(event_args.event); + /* delete an object while it's being waited on */

wait_args.timeout = get_abs_timeout(200); wait_args.owner = 123; + objs[1] = mutex_args.mutex; ret = pthread_create(&thread, NULL, wait_thread, &thread_args); EXPECT_EQ(0, ret);

@@ -823,12 +930,14 @@ TEST(wake_any)

TEST(wake_all) { + struct ntsync_event_args manual_event_args = {0}; + struct ntsync_event_args auto_event_args = {0}; struct ntsync_mutex_args mutex_args = {0}; struct ntsync_wait_args wait_args = {0}; struct ntsync_sem_args sem_args = {0}; struct wait_args thread_args; - int objs[2], fd, ret; - __u32 count, index; + __u32 count, index, signaled; + int objs[4], fd, ret; pthread_t thread;

fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); @@ -848,12 +957,24 @@ TEST(wake_all) EXPECT_EQ(0, ret); EXPECT_NE(0xdeadbeef, mutex_args.mutex);

+ manual_event_args.manual = true; + manual_event_args.signaled = true; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &manual_event_args); + EXPECT_EQ(0, ret); + + auto_event_args.manual = false; + auto_event_args.signaled = true; + ret = ioctl(fd, NTSYNC_IOC_CREATE_EVENT, &auto_event_args); + EXPECT_EQ(0, ret); + objs[0] = sem_args.sem; objs[1] = mutex_args.mutex; + objs[2] = manual_event_args.event; + objs[3] = auto_event_args.event;

wait_args.timeout = get_abs_timeout(1000); wait_args.objs = (uintptr_t)objs; - wait_args.count = 2; + wait_args.count = 4; wait_args.owner = 456; thread_args.fd = fd; thread_args.args = &wait_args; @@ -887,12 +1008,32 @@ TEST(wake_all)

check_mutex_state(mutex_args.mutex, 0, 0);

+ ret = ioctl(manual_event_args.event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + count = 2; ret = post_sem(sem_args.sem, &count); EXPECT_EQ(0, ret); EXPECT_EQ(0, count); + check_sem_state(sem_args.sem, 2, 3); + + ret = ioctl(auto_event_args.event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(1, signaled); + + ret = ioctl(manual_event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + + ret = ioctl(auto_event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, signaled); + check_sem_state(sem_args.sem, 1, 3); check_mutex_state(mutex_args.mutex, 1, 456); + check_event_state(manual_event_args.event, 1, 1); + check_event_state(auto_event_args.event, 0, 0);

ret = wait_for_thread(thread, 100); EXPECT_EQ(0, ret); @@ -910,6 +1051,8 @@ TEST(wake_all)

close(sem_args.sem); close(mutex_args.mutex); + close(manual_event_args.event); + close(auto_event_args.event);

ret = wait_for_thread(thread, 200); EXPECT_EQ(0, ret);

Expand the alert tests to cover alerting a thread mid-wait, to test that the relevant scheduling logic works correctly.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- .../testing/selftests/drivers/ntsync/ntsync.c | 62 +++++++++++++++++++ 1 file changed, 62 insertions(+)

diff --git a/tools/testing/selftests/drivers/ntsync/ntsync.c b/tools/testing/selftests/drivers/ntsync/ntsync.c index 6c00a55909aa..09153d0686ac 100644 --- a/tools/testing/selftests/drivers/ntsync/ntsync.c +++ b/tools/testing/selftests/drivers/ntsync/ntsync.c @@ -1080,9 +1080,12 @@ TEST(wake_all) TEST(alert_any) { struct ntsync_event_args event_args = {0}; + struct ntsync_wait_args wait_args = {0}; struct ntsync_sem_args sem_args = {0}; __u32 index, count, signaled; + struct wait_args thread_args; int objs[2], fd, ret; + pthread_t thread;

fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); ASSERT_LE(0, fd); @@ -1130,6 +1133,34 @@ TEST(alert_any) EXPECT_EQ(0, ret); EXPECT_EQ(2, index);

+ /* test wakeup via alert */ + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + + wait_args.timeout = get_abs_timeout(1000); + wait_args.objs = (uintptr_t)objs; + wait_args.count = 2; + wait_args.owner = 123; + wait_args.index = 0xdeadbeef; + wait_args.alert = event_args.event; + thread_args.fd = fd; + thread_args.args = &wait_args; + thread_args.request = NTSYNC_IOC_WAIT_ANY; + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(2, wait_args.index); + close(event_args.event);

/* test with an auto-reset event */ @@ -1166,9 +1197,12 @@ TEST(alert_any) TEST(alert_all) { struct ntsync_event_args event_args = {0}; + struct ntsync_wait_args wait_args = {0}; struct ntsync_sem_args sem_args = {0}; + struct wait_args thread_args; __u32 index, count, signaled; int objs[2], fd, ret; + pthread_t thread;

fd = open("/dev/ntsync", O_CLOEXEC | O_RDONLY); ASSERT_LE(0, fd); @@ -1202,6 +1236,34 @@ TEST(alert_all) EXPECT_EQ(0, ret); EXPECT_EQ(2, index);

+ /* test wakeup via alert */ + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_RESET, &signaled); + EXPECT_EQ(0, ret); + + wait_args.timeout = get_abs_timeout(1000); + wait_args.objs = (uintptr_t)objs; + wait_args.count = 2; + wait_args.owner = 123; + wait_args.index = 0xdeadbeef; + wait_args.alert = event_args.event; + thread_args.fd = fd; + thread_args.args = &wait_args; + thread_args.request = NTSYNC_IOC_WAIT_ALL; + ret = pthread_create(&thread, NULL, wait_thread, &thread_args); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(ETIMEDOUT, ret); + + ret = ioctl(event_args.event, NTSYNC_IOC_EVENT_SET, &signaled); + EXPECT_EQ(0, ret); + + ret = wait_for_thread(thread, 100); + EXPECT_EQ(0, ret); + EXPECT_EQ(0, thread_args.ret); + EXPECT_EQ(2, wait_args.index); + close(event_args.event);

/* test with an auto-reset event */

Add an overall explanation of the driver architecture, and complete and precise specification for its intended behaviour.

Signed-off-by: Elizabeth Figura zfigura@codeweavers.com --- Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/ntsync.rst | 390 +++++++++++++++++++++++++ 2 files changed, 391 insertions(+) create mode 100644 Documentation/userspace-api/ntsync.rst

diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index 09f61bd2ac2e..f5a72ed27def 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -34,6 +34,7 @@ place where this information is gathered. tee isapnp dcdbas + ntsync

.. only:: subproject and html

diff --git a/Documentation/userspace-api/ntsync.rst b/Documentation/userspace-api/ntsync.rst new file mode 100644 index 000000000000..bda9401f6747 --- /dev/null +++ b/Documentation/userspace-api/ntsync.rst @@ -0,0 +1,390 @@ +=================================== +NT synchronization primitive driver +=================================== + +This page documents the user-space API for the ntsync driver. + +ntsync is a support driver for emulation of NT synchronization +primitives by user-space NT emulators. It exists because implementation +in user-space, using existing tools, cannot match Windows performance +while offering accurate semantics. It is implemented entirely in +software, and does not drive any hardware device. + +This interface is meant as a compatibility tool only, and should not +be used for general synchronization. Instead use generic, versatile +interfaces such as futex(2) and poll(2). + +Synchronization primitives +========================== + +The ntsync driver exposes three types of synchronization primitives: +semaphores, mutexes, and events. + +A semaphore holds a single volatile 32-bit counter, and a static 32-bit +integer denoting the maximum value. It is considered signaled when the +counter is nonzero. The counter is decremented by one when a wait is +satisfied. Both the initial and maximum count are established when the +semaphore is created. + +A mutex holds a volatile 32-bit recursion count, and a volatile 32-bit +identifier denoting its owner. A mutex is considered signaled when its +owner is zero (indicating that it is not owned). The recursion count is +incremented when a wait is satisfied, and ownership is set to the given +identifier. + +A mutex also holds an internal flag denoting whether its previous owner +has died; such a mutex is said to be abandoned. Owner death is not +tracked automatically based on thread death, but rather must be +communicated using ``NTSYNC_IOC_MUTEX_KILL``. An abandoned mutex is +inherently considered unowned. + +Except for the "unowned" semantics of zero, the actual value of the +owner identifier is not interpreted by the ntsync driver at all. The +intended use is to store a thread identifier; however, the ntsync +driver does not actually validate that a calling thread provides +consistent or unique identifiers. + +An event holds a volatile boolean state denoting whether it is signaled +or not. There are two types of events, auto-reset and manual-reset. An +auto-reset event is designaled when a wait is satisfied; a manual-reset +event is not. The event type is specified when the event is created. + +Unless specified otherwise, all operations on an object are atomic and +totally ordered with respect to other operations on the same object. + +Objects are represented by files. When all file descriptors to an +object are closed, that object is deleted. + +Char device +=========== + +The ntsync driver creates a single char device /dev/ntsync. Each file +description opened on the device represents a unique instance intended +to back an individual NT virtual machine. Objects created by one ntsync +instance may only be used with other objects created by the same +instance. + +ioctl reference +=============== + +All operations on the device are done through ioctls. There are four +structures used in ioctl calls:: + + struct ntsync_sem_args { + __u32 sem; + __u32 count; + __u32 max; + }; + + struct ntsync_mutex_args { + __u32 mutex; + __u32 owner; + __u32 count; + }; + + struct ntsync_event_args { + __u32 event; + __u32 signaled; + __u32 manual; + }; + + struct ntsync_wait_args { + __u64 timeout; + __u64 objs; + __u32 count; + __u32 owner; + __u32 index; + __u32 alert; + }; + +Depending on the ioctl, members of the structure may be used as input, +output, or not at all. All ioctls return 0 on success. + +The ioctls on the device file are as follows: + +.. c:macro:: NTSYNC_IOC_CREATE_SEM + + Create a semaphore object. Takes a pointer to struct + :c:type:`ntsync_sem_args`, which is used as follows: + + .. list-table:: + + * - ``sem`` + - On output, contains a file descriptor to the created semaphore. + * - ``count`` + - Initial count of the semaphore. + * - ``max`` + - Maximum count of the semaphore. + + Fails with ``EINVAL`` if ``count`` is greater than ``max``. + +.. c:macro:: NTSYNC_IOC_CREATE_MUTEX + + Create a mutex object. Takes a pointer to struct + :c:type:`ntsync_mutex_args`, which is used as follows: + + .. list-table:: + + * - ``mutex`` + - On output, contains a file descriptor to the created mutex. + * - ``count`` + - Initial recursion count of the mutex. + * - ``owner`` + - Initial owner of the mutex. + + If ``owner`` is nonzero and ``count`` is zero, or if ``owner`` is + zero and ``count`` is nonzero, the function fails with ``EINVAL``. + +.. c:macro:: NTSYNC_IOC_CREATE_EVENT + + Create an event object. Takes a pointer to struct + :c:type:`ntsync_event_args`, which is used as follows: + + .. list-table:: + + * - ``event`` + - On output, contains a file descriptor to the created event. + * - ``signaled`` + - If nonzero, the event is initially signaled, otherwise + nonsignaled. + * - ``manual`` + - If nonzero, the event is a manual-reset event, otherwise + auto-reset. + +The ioctls on the individual objects are as follows: + +.. c:macro:: NTSYNC_IOC_SEM_POST + + Post to a semaphore object. Takes a pointer to a 32-bit integer, + which on input holds the count to be added to the semaphore, and on + output contains its previous count. + + If adding to the semaphore's current count would raise the latter + past the semaphore's maximum count, the ioctl fails with + ``EOVERFLOW`` and the semaphore is not affected. If raising the + semaphore's count causes it to become signaled, eligible threads + waiting on this semaphore will be woken and the semaphore's count + decremented appropriately. + +.. c:macro:: NTSYNC_IOC_MUTEX_UNLOCK + + Release a mutex object. Takes a pointer to struct + :c:type:`ntsync_mutex_args`, which is used as follows: + + .. list-table:: + + * - ``mutex`` + - Ignored. + * - ``owner`` + - Specifies the owner trying to release this mutex. + * - ``count`` + - On output, contains the previous recursion count. + + If ``owner`` is zero, the ioctl fails with ``EINVAL``. If ``owner`` + is not the current owner of the mutex, the ioctl fails with + ``EPERM``. + + The mutex's count will be decremented by one. If decrementing the + mutex's count causes it to become zero, the mutex is marked as + unowned and signaled, and eligible threads waiting on it will be + woken as appropriate. + +.. c:macro:: NTSYNC_IOC_SET_EVENT + + Signal an event object. Takes a pointer to a 32-bit integer, which on + output contains the previous state of the event. + + Eligible threads will be woken, and auto-reset events will be + designaled appropriately. + +.. c:macro:: NTSYNC_IOC_RESET_EVENT + + Designal an event object. Takes a pointer to a 32-bit integer, which + on output contains the previous state of the event. + +.. c:macro:: NTSYNC_IOC_PULSE_EVENT + + Wake threads waiting on an event object while leaving it in an + unsignaled state. Takes a pointer to a 32-bit integer, which on + output contains the previous state of the event. + + A pulse operation can be thought of as a set followed by a reset, + performed as a single atomic operation. If two threads are waiting on + an auto-reset event which is pulsed, only one will be woken. If two + threads are waiting a manual-reset event which is pulsed, both will + be woken. However, in both cases, the event will be unsignaled + afterwards, and a simultaneous read operation will always report the + event as unsignaled. + +.. c:macro:: NTSYNC_IOC_READ_SEM + + Read the current state of a semaphore object. Takes a pointer to + struct :c:type:`ntsync_sem_args`, which is used as follows: + + .. list-table:: + + * - ``sem`` + - Ignored. + * - ``count`` + - On output, contains the current count of the semaphore. + * - ``max`` + - On output, contains the maximum count of the semaphore. + +.. c:macro:: NTSYNC_IOC_READ_MUTEX + + Read the current state of a mutex object. Takes a pointer to struct + :c:type:`ntsync_mutex_args`, which is used as follows: + + .. list-table:: + + * - ``mutex`` + - Ignored. + * - ``owner`` + - On output, contains the current owner of the mutex, or zero + if the mutex is not currently owned. + * - ``count`` + - On output, contains the current recursion count of the mutex. + + If the mutex is marked as abandoned, the function fails with + ``EOWNERDEAD``. In this case, ``count`` and ``owner`` are set to + zero. + +.. c:macro:: NTSYNC_IOC_READ_EVENT + + Read the current state of an event object. Takes a pointer to struct + :c:type:`ntsync_event_args`, which is used as follows: + + .. list-table:: + + * - ``event`` + - Ignored. + * - ``signaled`` + - On output, contains the current state of the event. + * - ``manual`` + - On output, contains 1 if the event is a manual-reset event, + and 0 otherwise. + +.. c:macro:: NTSYNC_IOC_KILL_OWNER + + Mark a mutex as unowned and abandoned if it is owned by the given + owner. Takes an input-only pointer to a 32-bit integer denoting the + owner. If the owner is zero, the ioctl fails with ``EINVAL``. If the + owner does not own the mutex, the function fails with ``EPERM``. + + Eligible threads waiting on the mutex will be woken as appropriate + (and such waits will fail with ``EOWNERDEAD``, as described below). + +.. c:macro:: NTSYNC_IOC_WAIT_ANY + + Poll on any of a list of objects, atomically acquiring at most one. + Takes a pointer to struct :c:type:`ntsync_wait_args`, which is + used as follows: + + .. list-table:: + + * - ``timeout`` + - Absolute timeout in nanoseconds, measured against the + MONOTONIC clock. If the timeout is equal to or earlier than + the current time, the function returns immediately without + sleeping. If ``timeout`` is U64_MAX, the function will sleep + until an object is signaled, and will not fail with + ``ETIMEDOUT``. + * - ``objs`` + - Pointer to an array of ``count`` file descriptors + (specified as an integer so that the structure has the same + size regardless of architecture). If any object is + invalid, the function fails with ``EINVAL``. + * - ``count`` + - Number of objects specified in the ``objs`` array. + If greater than ``NTSYNC_MAX_WAIT_COUNT``, the function fails + with ``EINVAL``. + * - ``owner`` + - Mutex owner identifier. If any object in ``objs`` is a mutex, + the ioctl will attempt to acquire that mutex on behalf of + ``owner``. If ``owner`` is zero, the ioctl fails with + ``EINVAL``. + * - ``index`` + - On success, contains the index (into ``objs``) of the object + which was signaled. If ``alert`` was signaled instead, + this contains ``count``. + * - ``alert`` + - Optional event object file descriptor. If nonzero, this + specifies an "alert" event object which, if signaled, will + terminate the wait. If nonzero, the identifier must point to a + valid event. + + This function attempts to acquire one of the given objects. If unable + to do so, it sleeps until an object becomes signaled, subsequently + acquiring it, or the timeout expires. In the latter case the ioctl + fails with ``ETIMEDOUT``. The function only acquires one object, even + if multiple objects are signaled. + + A semaphore is considered to be signaled if its count is nonzero, and + is acquired by decrementing its count by one. A mutex is considered + to be signaled if it is unowned or if its owner matches the ``owner`` + argument, and is acquired by incrementing its recursion count by one + and setting its owner to the ``owner`` argument. An auto-reset event + is acquired by designaling it; a manual-reset event is not affected + by acquisition. + + Acquisition is atomic and totally ordered with respect to other + operations on the same object. If two wait operations (with different + ``owner`` identifiers) are queued on the same mutex, only one is + signaled. If two wait operations are queued on the same semaphore, + and a value of one is posted to it, only one is signaled. The order + in which threads are signaled is not specified. + + If an abandoned mutex is acquired, the ioctl fails with + ``EOWNERDEAD``. Although this is a failure return, the function may + otherwise be considered successful. The mutex is marked as owned by + the given owner (with a recursion count of 1) and as no longer + abandoned, and ``index`` is still set to the index of the mutex. + + The ``alert`` argument is an "extra" event which can terminate the + wait, independently of all other objects. If members of ``objs`` and + ``alert`` are both simultaneously signaled, a member of ``objs`` will + always be given priority and acquired first. + + It is valid to pass the same object more than once, including by + passing the same event in the ``objs`` array and in ``alert``. If a + wakeup occurs due to that object being signaled, ``index`` is set to + the lowest index corresponding to that object. + + The function may fail with ``EINTR`` if a signal is received. + +.. c:macro:: NTSYNC_IOC_WAIT_ALL + + Poll on a list of objects, atomically acquiring all of them. Takes a + pointer to struct :c:type:`ntsync_wait_args`, which is used + identically to ``NTSYNC_IOC_WAIT_ANY``, except that ``index`` is + always filled with zero on success if not woken via alert. + + This function attempts to simultaneously acquire all of the given + objects. If unable to do so, it sleeps until all objects become + simultaneously signaled, subsequently acquiring them, or the timeout + expires. In the latter case the ioctl fails with ``ETIMEDOUT`` and no + objects are modified. + + Objects may become signaled and subsequently designaled (through + acquisition by other threads) while this thread is sleeping. Only + once all objects are simultaneously signaled does the ioctl acquire + them and return. The entire acquisition is atomic and totally ordered + with respect to other operations on any of the given objects. + + If an abandoned mutex is acquired, the ioctl fails with + ``EOWNERDEAD``. Similarly to ``NTSYNC_IOC_WAIT_ANY``, all objects are + nevertheless marked as acquired. Note that if multiple mutex objects + are specified, there is no way to know which were marked as + abandoned. + + As with "any" waits, the ``alert`` argument is an "extra" event which + can terminate the wait. Critically, however, an "all" wait will + succeed if all members in ``objs`` are signaled, *or* if ``alert`` is + signaled. In the latter case ``index`` will be set to ``count``. As + with "any" waits, if both conditions are filled, the former takes + priority, and objects in ``objs`` will be acquired. + + Unlike ``NTSYNC_IOC_WAIT_ANY``, it is not valid to pass the same + object more than once, nor is it valid to pass the same object in + ``objs`` and in ``alert``. If this is attempted, the function fails + with ``EINVAL``.