diff options
| -rw-r--r-- | Documentation/userspace-api/ioctl/ioctl-number.rst | 1 | ||||
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | drivers/fwctl/main.c | 143 | ||||
| -rw-r--r-- | include/linux/fwctl.h | 46 | ||||
| -rw-r--r-- | include/uapi/fwctl/fwctl.h | 38 |
5 files changed, 224 insertions, 5 deletions
diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst index 6d1465315df3..3410b020a9d0 100644 --- a/Documentation/userspace-api/ioctl/ioctl-number.rst +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst @@ -331,6 +331,7 @@ Code Seq# Include File Comments 0x97 00-7F fs/ceph/ioctl.h Ceph file system 0x99 00-0F 537-Addinboard driver <mailto:buk@buks.ipn.de> +0x9A 00-0F include/uapi/fwctl/fwctl.h 0xA0 all linux/sdp/sdp.h Industrial Device Project <mailto:kenji@bitgate.com> 0xA1 0 linux/vtpm_proxy.h TPM Emulator Proxy Driver diff --git a/MAINTAINERS b/MAINTAINERS index a05b7ac4f0cb..e8baaba27d8e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -9565,6 +9565,7 @@ R: Jonathan Cameron <Jonathan.Cameron@huawei.com> S: Maintained F: drivers/fwctl/ F: include/linux/fwctl.h +F: include/uapi/fwctl/ GALAXYCORE GC0308 CAMERA SENSOR DRIVER M: Sebastian Reichel <sre@kernel.org> diff --git a/drivers/fwctl/main.c b/drivers/fwctl/main.c index 76c4edec20af..4bba6109712e 100644 --- a/drivers/fwctl/main.c +++ b/drivers/fwctl/main.c @@ -10,6 +10,8 @@ #include <linux/module.h> #include <linux/slab.h> +#include <uapi/fwctl/fwctl.h> + enum { FWCTL_MAX_DEVICES = 4096, }; @@ -18,20 +20,128 @@ static_assert(FWCTL_MAX_DEVICES < (1U << MINORBITS)); static dev_t fwctl_dev; static DEFINE_IDA(fwctl_ida); +struct fwctl_ucmd { + struct fwctl_uctx *uctx; + void __user *ubuffer; + void *cmd; + u32 user_size; +}; + +/* On stack memory for the ioctl structs */ +union fwctl_ucmd_buffer { +}; + +struct fwctl_ioctl_op { + unsigned int size; + unsigned int min_size; + unsigned int ioctl_num; + int (*execute)(struct fwctl_ucmd *ucmd); +}; + +#define IOCTL_OP(_ioctl, _fn, _struct, _last) \ + [_IOC_NR(_ioctl) - FWCTL_CMD_BASE] = { \ + .size = sizeof(_struct) + \ + BUILD_BUG_ON_ZERO(sizeof(union fwctl_ucmd_buffer) < \ + sizeof(_struct)), \ + .min_size = offsetofend(_struct, _last), \ + .ioctl_num = _ioctl, \ + .execute = _fn, \ + } +static const struct fwctl_ioctl_op fwctl_ioctl_ops[] = { +}; + +static long fwctl_fops_ioctl(struct file *filp, unsigned int cmd, + unsigned long arg) +{ + struct fwctl_uctx *uctx = filp->private_data; + const struct fwctl_ioctl_op *op; + struct fwctl_ucmd ucmd = {}; + union fwctl_ucmd_buffer buf; + unsigned int nr; + int ret; + + nr = _IOC_NR(cmd); + if ((nr - FWCTL_CMD_BASE) >= ARRAY_SIZE(fwctl_ioctl_ops)) + return -ENOIOCTLCMD; + + op = &fwctl_ioctl_ops[nr - FWCTL_CMD_BASE]; + if (op->ioctl_num != cmd) + return -ENOIOCTLCMD; + + ucmd.uctx = uctx; + ucmd.cmd = &buf; + ucmd.ubuffer = (void __user *)arg; + ret = get_user(ucmd.user_size, (u32 __user *)ucmd.ubuffer); + if (ret) + return ret; + + if (ucmd.user_size < op->min_size) + return -EINVAL; + + ret = copy_struct_from_user(ucmd.cmd, op->size, ucmd.ubuffer, + ucmd.user_size); + if (ret) + return ret; + + guard(rwsem_read)(&uctx->fwctl->registration_lock); + if (!uctx->fwctl->ops) + return -ENODEV; + return op->execute(&ucmd); +} + static int fwctl_fops_open(struct inode *inode, struct file *filp) { struct fwctl_device *fwctl = container_of(inode->i_cdev, struct fwctl_device, cdev); + int ret; + + guard(rwsem_read)(&fwctl->registration_lock); + if (!fwctl->ops) + return -ENODEV; + + struct fwctl_uctx *uctx __free(kfree) = + kzalloc(fwctl->ops->uctx_size, GFP_KERNEL_ACCOUNT); + if (!uctx) + return -ENOMEM; + + uctx->fwctl = fwctl; + ret = fwctl->ops->open_uctx(uctx); + if (ret) + return ret; + + scoped_guard(mutex, &fwctl->uctx_list_lock) { + list_add_tail(&uctx->uctx_list_entry, &fwctl->uctx_list); + } get_device(&fwctl->dev); - filp->private_data = fwctl; + filp->private_data = no_free_ptr(uctx); return 0; } +static void fwctl_destroy_uctx(struct fwctl_uctx *uctx) +{ + lockdep_assert_held(&uctx->fwctl->uctx_list_lock); + list_del(&uctx->uctx_list_entry); + uctx->fwctl->ops->close_uctx(uctx); +} + static int fwctl_fops_release(struct inode *inode, struct file *filp) { - struct fwctl_device *fwctl = filp->private_data; + struct fwctl_uctx *uctx = filp->private_data; + struct fwctl_device *fwctl = uctx->fwctl; + scoped_guard(rwsem_read, &fwctl->registration_lock) { + /* + * NULL ops means fwctl_unregister() has already removed the + * driver and destroyed the uctx. + */ + if (fwctl->ops) { + guard(mutex)(&fwctl->uctx_list_lock); + fwctl_destroy_uctx(uctx); + } + } + + kfree(uctx); fwctl_put(fwctl); return 0; } @@ -40,6 +150,7 @@ static const struct file_operations fwctl_fops = { .owner = THIS_MODULE, .open = fwctl_fops_open, .release = fwctl_fops_release, + .unlocked_ioctl = fwctl_fops_ioctl, }; static void fwctl_device_release(struct device *device) @@ -48,6 +159,7 @@ static void fwctl_device_release(struct device *device) container_of(device, struct fwctl_device, dev); ida_free(&fwctl_ida, fwctl->dev.devt - fwctl_dev); + mutex_destroy(&fwctl->uctx_list_lock); kfree(fwctl); } @@ -71,9 +183,6 @@ _alloc_device(struct device *parent, const struct fwctl_ops *ops, size_t size) if (!fwctl) return NULL; - fwctl->dev.class = &fwctl_class; - fwctl->dev.parent = parent; - devnum = ida_alloc_max(&fwctl_ida, FWCTL_MAX_DEVICES - 1, GFP_KERNEL); if (devnum < 0) return NULL; @@ -82,6 +191,10 @@ _alloc_device(struct device *parent, const struct fwctl_ops *ops, size_t size) fwctl->dev.class = &fwctl_class; fwctl->dev.parent = parent; + init_rwsem(&fwctl->registration_lock); + mutex_init(&fwctl->uctx_list_lock); + INIT_LIST_HEAD(&fwctl->uctx_list); + device_initialize(&fwctl->dev); return_ptr(fwctl); } @@ -132,6 +245,10 @@ EXPORT_SYMBOL_NS_GPL(fwctl_register, "FWCTL"); * Undoes fwctl_register(). On return no driver ops will be called. The * caller must still call fwctl_put() to free the fwctl. * + * Unregister will return even if userspace still has file descriptors open. + * This will call ops->close_uctx() on any open FDs and after return no driver + * op will be called. The FDs remain open but all fops will return -ENODEV. + * * The design of fwctl allows this sort of disassociation of the driver from the * subsystem primarily by keeping memory allocations owned by the core subsytem. * The fwctl_device and fwctl_uctx can both be freed without requiring a driver @@ -139,7 +256,23 @@ EXPORT_SYMBOL_NS_GPL(fwctl_register, "FWCTL"); */ void fwctl_unregister(struct fwctl_device *fwctl) { + struct fwctl_uctx *uctx; + cdev_device_del(&fwctl->cdev, &fwctl->dev); + + /* Disable and free the driver's resources for any still open FDs. */ + guard(rwsem_write)(&fwctl->registration_lock); + guard(mutex)(&fwctl->uctx_list_lock); + while ((uctx = list_first_entry_or_null(&fwctl->uctx_list, + struct fwctl_uctx, + uctx_list_entry))) + fwctl_destroy_uctx(uctx); + + /* + * The driver module may unload after this returns, the op pointer will + * not be valid. + */ + fwctl->ops = NULL; } EXPORT_SYMBOL_NS_GPL(fwctl_unregister, "FWCTL"); diff --git a/include/linux/fwctl.h b/include/linux/fwctl.h index 39d5059c9e59..faa4b2c780e0 100644 --- a/include/linux/fwctl.h +++ b/include/linux/fwctl.h @@ -11,7 +11,30 @@ struct fwctl_device; struct fwctl_uctx; +/** + * struct fwctl_ops - Driver provided operations + * + * fwctl_unregister() will wait until all excuting ops are completed before it + * returns. Drivers should be mindful to not let their ops run for too long as + * it will block device hot unplug and module unloading. + */ struct fwctl_ops { + /** + * @uctx_size: The size of the fwctl_uctx struct to allocate. The first + * bytes of this memory will be a fwctl_uctx. The driver can use the + * remaining bytes as its private memory. + */ + size_t uctx_size; + /** + * @open_uctx: Called when a file descriptor is opened before the uctx + * is ever used. + */ + int (*open_uctx)(struct fwctl_uctx *uctx); + /** + * @close_uctx: Called when the uctx is destroyed, usually when the FD + * is closed. + */ + void (*close_uctx)(struct fwctl_uctx *uctx); }; /** @@ -26,6 +49,15 @@ struct fwctl_device { struct device dev; /* private: */ struct cdev cdev; + + /* Protect uctx_list */ + struct mutex uctx_list_lock; + struct list_head uctx_list; + /* + * Protect ops, held for write when ops becomes NULL during unregister, + * held for read whenever ops is loaded or an ops function is running. + */ + struct rw_semaphore registration_lock; const struct fwctl_ops *ops; }; @@ -66,4 +98,18 @@ DEFINE_FREE(fwctl, struct fwctl_device *, if (_T) fwctl_put(_T)); int fwctl_register(struct fwctl_device *fwctl); void fwctl_unregister(struct fwctl_device *fwctl); +/** + * struct fwctl_uctx - Per user FD context + * @fwctl: fwctl instance that owns the context + * + * Every FD opened by userspace will get a unique context allocation. Any driver + * private data will follow immediately after. + */ +struct fwctl_uctx { + struct fwctl_device *fwctl; + /* private: */ + /* Head at fwctl_device::uctx_list */ + struct list_head uctx_list_entry; +}; + #endif diff --git a/include/uapi/fwctl/fwctl.h b/include/uapi/fwctl/fwctl.h new file mode 100644 index 000000000000..8f5fe821cf28 --- /dev/null +++ b/include/uapi/fwctl/fwctl.h @@ -0,0 +1,38 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* Copyright (c) 2024-2025, NVIDIA CORPORATION & AFFILIATES. + */ +#ifndef _UAPI_FWCTL_H +#define _UAPI_FWCTL_H + +#define FWCTL_TYPE 0x9A + +/** + * DOC: General ioctl format + * + * The ioctl interface follows a general format to allow for extensibility. Each + * ioctl is passed a structure pointer as the argument providing the size of + * the structure in the first u32. The kernel checks that any structure space + * beyond what it understands is 0. This allows userspace to use the backward + * compatible portion while consistently using the newer, larger, structures. + * + * ioctls use a standard meaning for common errnos: + * + * - ENOTTY: The IOCTL number itself is not supported at all + * - E2BIG: The IOCTL number is supported, but the provided structure has + * non-zero in a part the kernel does not understand. + * - EOPNOTSUPP: The IOCTL number is supported, and the structure is + * understood, however a known field has a value the kernel does not + * understand or support. + * - EINVAL: Everything about the IOCTL was understood, but a field is not + * correct. + * - ENOMEM: Out of memory. + * - ENODEV: The underlying device has been hot-unplugged and the FD is + * orphaned. + * + * As well as additional errnos, within specific ioctls. + */ +enum { + FWCTL_CMD_BASE = 0, +}; + +#endif |