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![Jan Beulich](/assets/img/avatar_default.png)
gcc permitting variable length arrays makes the current construct used for BUILD_BUG_ON() useless, as that doesn't produce any diagnostic if the controlling expression isn't really constant. Instead, this patch makes it so that a bit field gets used here. Consequently, those uses where the condition isn't really constant now also need fixing. Note that in the gfp.h, kmemcheck.h, and virtio_config.h cases MAYBE_BUILD_BUG_ON() really just serves documentation purposes - even if the expression is compile time constant (__builtin_constant_p() yields true), the array is still deemed of variable length by gcc, and hence the whole expression doesn't have the intended effect. [akpm@linux-foundation.org: make arch/sparc/include/asm/vio.h compile] [akpm@linux-foundation.org: more nonsensical assertions in tpm.c..] Signed-off-by: Jan Beulich <jbeulich@novell.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Rajiv Andrade <srajiv@linux.vnet.ibm.com> Cc: Mimi Zohar <zohar@us.ibm.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
157 lines
5.7 KiB
C
157 lines
5.7 KiB
C
#ifndef _LINUX_VIRTIO_CONFIG_H
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#define _LINUX_VIRTIO_CONFIG_H
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/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
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* anyone can use the definitions to implement compatible drivers/servers. */
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/* Virtio devices use a standardized configuration space to define their
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* features and pass configuration information, but each implementation can
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* store and access that space differently. */
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#include <linux/types.h>
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/* Status byte for guest to report progress, and synchronize features. */
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/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
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#define VIRTIO_CONFIG_S_ACKNOWLEDGE 1
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/* We have found a driver for the device. */
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#define VIRTIO_CONFIG_S_DRIVER 2
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/* Driver has used its parts of the config, and is happy */
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#define VIRTIO_CONFIG_S_DRIVER_OK 4
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/* We've given up on this device. */
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#define VIRTIO_CONFIG_S_FAILED 0x80
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/* Some virtio feature bits (currently bits 28 through 31) are reserved for the
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* transport being used (eg. virtio_ring), the rest are per-device feature
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* bits. */
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#define VIRTIO_TRANSPORT_F_START 28
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#define VIRTIO_TRANSPORT_F_END 32
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/* Do we get callbacks when the ring is completely used, even if we've
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* suppressed them? */
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#define VIRTIO_F_NOTIFY_ON_EMPTY 24
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#ifdef __KERNEL__
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#include <linux/err.h>
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#include <linux/virtio.h>
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/**
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* virtio_config_ops - operations for configuring a virtio device
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* @get: read the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to write the field value into.
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* len: the length of the buffer
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* @set: write the value of a configuration field
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* vdev: the virtio_device
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* offset: the offset of the configuration field
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* buf: the buffer to read the field value from.
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* len: the length of the buffer
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* @get_status: read the status byte
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* vdev: the virtio_device
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* Returns the status byte
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* @set_status: write the status byte
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* vdev: the virtio_device
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* status: the new status byte
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* @request_vqs: request the specified number of virtqueues
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* vdev: the virtio_device
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* max_vqs: the max number of virtqueues we want
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* If supplied, must call before any virtqueues are instantiated.
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* To modify the max number of virtqueues after request_vqs has been
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* called, call free_vqs and then request_vqs with a new value.
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* @free_vqs: cleanup resources allocated by request_vqs
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* vdev: the virtio_device
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* If supplied, must call after all virtqueues have been deleted.
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* @reset: reset the device
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* vdev: the virtio device
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* After this, status and feature negotiation must be done again
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* @find_vqs: find virtqueues and instantiate them.
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* vdev: the virtio_device
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* nvqs: the number of virtqueues to find
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* vqs: on success, includes new virtqueues
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* callbacks: array of callbacks, for each virtqueue
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* names: array of virtqueue names (mainly for debugging)
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* Returns 0 on success or error status
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* @del_vqs: free virtqueues found by find_vqs().
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* @get_features: get the array of feature bits for this device.
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* vdev: the virtio_device
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* Returns the first 32 feature bits (all we currently need).
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* @finalize_features: confirm what device features we'll be using.
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* vdev: the virtio_device
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* This gives the final feature bits for the device: it can change
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* the dev->feature bits if it wants.
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*/
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typedef void vq_callback_t(struct virtqueue *);
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struct virtio_config_ops {
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void (*get)(struct virtio_device *vdev, unsigned offset,
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void *buf, unsigned len);
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void (*set)(struct virtio_device *vdev, unsigned offset,
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const void *buf, unsigned len);
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u8 (*get_status)(struct virtio_device *vdev);
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void (*set_status)(struct virtio_device *vdev, u8 status);
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void (*reset)(struct virtio_device *vdev);
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int (*find_vqs)(struct virtio_device *, unsigned nvqs,
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struct virtqueue *vqs[],
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vq_callback_t *callbacks[],
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const char *names[]);
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void (*del_vqs)(struct virtio_device *);
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u32 (*get_features)(struct virtio_device *vdev);
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void (*finalize_features)(struct virtio_device *vdev);
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};
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/* If driver didn't advertise the feature, it will never appear. */
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void virtio_check_driver_offered_feature(const struct virtio_device *vdev,
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unsigned int fbit);
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/**
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* virtio_has_feature - helper to determine if this device has this feature.
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* @vdev: the device
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* @fbit: the feature bit
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*/
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static inline bool virtio_has_feature(const struct virtio_device *vdev,
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unsigned int fbit)
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{
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/* Did you forget to fix assumptions on max features? */
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MAYBE_BUILD_BUG_ON(fbit >= 32);
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if (fbit < VIRTIO_TRANSPORT_F_START)
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virtio_check_driver_offered_feature(vdev, fbit);
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return test_bit(fbit, vdev->features);
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}
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/**
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* virtio_config_val - look for a feature and get a virtio config entry.
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* @vdev: the virtio device
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* @fbit: the feature bit
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* @offset: the type to search for.
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* @val: a pointer to the value to fill in.
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*
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* The return value is -ENOENT if the feature doesn't exist. Otherwise
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* the config value is copied into whatever is pointed to by v. */
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#define virtio_config_val(vdev, fbit, offset, v) \
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virtio_config_buf((vdev), (fbit), (offset), (v), sizeof(*v))
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static inline int virtio_config_buf(struct virtio_device *vdev,
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unsigned int fbit,
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unsigned int offset,
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void *buf, unsigned len)
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{
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if (!virtio_has_feature(vdev, fbit))
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return -ENOENT;
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vdev->config->get(vdev, offset, buf, len);
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return 0;
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}
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static inline
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struct virtqueue *virtio_find_single_vq(struct virtio_device *vdev,
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vq_callback_t *c, const char *n)
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{
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vq_callback_t *callbacks[] = { c };
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const char *names[] = { n };
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struct virtqueue *vq;
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int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names);
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if (err < 0)
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return ERR_PTR(err);
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return vq;
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}
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#endif /* __KERNEL__ */
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#endif /* _LINUX_VIRTIO_CONFIG_H */
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