/*
* Detach an attached XPMEM address segment.
*/
int
xpmem_detach(vaddr_t at_vaddr)
{
struct xpmem_thread_group *tg;
struct xpmem_access_permit *ap;
struct xpmem_attachment *att;
tg = xpmem_tg_ref_by_gid(current->aspace->id);
if (IS_ERR(tg))
return PTR_ERR(tg);
att = xpmem_att_ref_by_vaddr(tg, at_vaddr);
if (IS_ERR(att)) {
xpmem_tg_deref(tg);
return PTR_ERR(att);
}
mutex_lock(&att->mutex);
if (att->flags & XPMEM_FLAG_DESTROYING) {
mutex_unlock(&att->mutex);
xpmem_att_deref(att);
xpmem_tg_deref(tg);
return 0;
}
att->flags |= XPMEM_FLAG_DESTROYING;
ap = att->ap;
xpmem_ap_ref(ap);
if (current->aspace->id != ap->tg->gid) {
att->flags &= ~XPMEM_FLAG_DESTROYING;
xpmem_ap_deref(ap);
mutex_unlock(&att->mutex);
xpmem_att_deref(att);
return -EACCES;
}
__xpmem_detach_att(ap, att);
mutex_unlock(&att->mutex);
xpmem_att_destroyable(att);
xpmem_ap_deref(ap);
xpmem_att_deref(att);
xpmem_tg_deref(tg);
return 0;
}
/*
* Get permission to access a specified segid.
*/
int
xpmem_get(xpmem_segid_t segid, int flags, int permit_type, void *permit_value,
xpmem_apid_t *apid_p)
{
xpmem_apid_t apid = 0;
int status = 0;
int shadow_seg = 0;
struct xpmem_segment *seg = NULL;
struct xpmem_thread_group *ap_tg, *seg_tg;
if (segid <= 0)
return -EINVAL;
if ((flags & ~(XPMEM_RDONLY | XPMEM_RDWR)) ||
(flags & (XPMEM_RDONLY | XPMEM_RDWR)) ==
(XPMEM_RDONLY | XPMEM_RDWR))
return -EINVAL;
switch (permit_type) {
case XPMEM_PERMIT_MODE:
case XPMEM_GLOBAL_MODE:
if (permit_value != NULL)
return -EINVAL;
break;
default:
return -EINVAL;
}
/* There are 2 cases that result in a remote lookup:
* (1) The thread group encoded in the segment does not exist locally.
*
* (2) The thread group exists locally, but the segment does not. The
* ids for thread groups are not globally unique, so it's possible that
* the same thread group id exists in two separate enclaves, but only
* one will own the segment
*/
seg_tg = xpmem_tg_ref_by_segid(segid);
if (IS_ERR(seg_tg)) {
seg_tg = xpmem_tg_ref_by_gid(current->aspace->id);
if (IS_ERR(seg_tg))
return PTR_ERR(seg_tg);
shadow_seg = 1;
}
if (!shadow_seg) {
seg = xpmem_seg_ref_by_segid(seg_tg, segid);
if (IS_ERR(seg))
shadow_seg = 1;
}
if (shadow_seg) {
/* No local segment found. Look for a remote one */
/* NOTE: in either case, the tg has already been ref'd. We ref the
* current process' tg if no tg is found for the segid
*/
status = xpmem_try_get_remote(seg_tg, segid, flags, permit_type,
permit_value);
if (status != 0) {
xpmem_tg_deref(seg_tg);
return status;
}
/* Now, get the shadow segment */
seg = xpmem_seg_ref_by_segid(seg_tg, segid);
if (IS_ERR(seg)) {
/* Error should be impossible here, but we'll
* check anyway. The shadow segment was created in
* xpmem_try_get_remote, so destroy it here */
xpmem_remove(segid);
xpmem_tg_deref(seg_tg);
return PTR_ERR(seg);
}
}
/* find accessor's thread group structure */
ap_tg = xpmem_tg_ref_by_gid(current->aspace->id);
if (IS_ERR(ap_tg)) {
BUG_ON(PTR_ERR(ap_tg) != -ENOENT);
status = -XPMEM_ERRNO_NOPROC;
goto err_ap_tg;
}
apid = xpmem_make_apid(ap_tg);
if (apid < 0) {
status = apid;
goto err_apid;
}
status = xpmem_get_segment(flags, permit_type, permit_value, apid,
seg, seg_tg, ap_tg);
if (status != 0)
goto err_get;
*apid_p = apid;
xpmem_tg_deref(ap_tg);
/*
* The following two derefs
*
* xpmem_seg_deref(seg);
* xpmem_tg_deref(seg_tg);
*
* aren't being done at this time in order to prevent the seg
* and seg_tg structures from being prematurely kmem_free'd as long as the
* potential for them to be referenced via this ap structure exists.
*
* These two derefs will be done by xpmem_release_ap() at the time
* this ap structure is destroyed.
*/
return status;
err_get:
err_apid:
xpmem_tg_deref(ap_tg);
err_ap_tg:
/* If we created a shadow segment, destroy it on error. Else, just
* deref it
*/
if (shadow_seg)
xpmem_remove(segid);
else
xpmem_seg_deref(seg);
xpmem_tg_deref(seg_tg);
return status;
}
