/** * \file drm_vm.c * Memory mapping for DRM * * \author Rickard E. (Rik) Faith * \author Gareth Hughes */ /* * Created: Mon Jan 4 08:58:31 1999 by faith@valinux.com * * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas. * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California. * All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ #include "drmP.h" /** * \c nopage method for AGP virtual memory. * * \param vma virtual memory area. * \param address access address. * \return pointer to the page structure. * * Find the right map and if it's AGP memory find the real physical page to * map, get the page, increment the use count and return it. */ #if __OS_HAS_AGP static __inline__ struct page *drm_do_vm_nopage(struct vm_area_struct *vma, unsigned long address) { drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_map_t *map = NULL; drm_map_list_t *r_list; struct list_head *list; /* * Find the right map */ if (!drm_core_has_AGP(dev)) goto vm_nopage_error; if (!dev->agp || !dev->agp->cant_use_aperture) goto vm_nopage_error; list_for_each(list, &dev->maplist->head) { r_list = list_entry(list, drm_map_list_t, head); map = r_list->map; if (!map) continue; if (map->offset == VM_OFFSET(vma)) break; } if (map && map->type == _DRM_AGP) { unsigned long offset = address - vma->vm_start; unsigned long baddr = VM_OFFSET(vma) + offset; struct drm_agp_mem *agpmem; struct page *page; #ifdef __alpha__ /* * Adjust to a bus-relative address */ baddr -= dev->hose->mem_space->start; #endif /* * It's AGP memory - find the real physical page to map */ for (agpmem = dev->agp->memory; agpmem; agpmem = agpmem->next) { if (agpmem->bound <= baddr && agpmem->bound + agpmem->pages * PAGE_SIZE > baddr) break; } if (!agpmem) goto vm_nopage_error; /* * Get the page, inc the use count, and return it */ offset = (baddr - agpmem->bound) >> PAGE_SHIFT; page = virt_to_page(__va(agpmem->memory->memory[offset])); get_page(page); #if 0 /* page_count() not defined everywhere */ DRM_DEBUG ("baddr = 0x%lx page = 0x%p, offset = 0x%lx, count=%d\n", baddr, __va(agpmem->memory->memory[offset]), offset, page_count(page)); #endif return page; } vm_nopage_error: return NOPAGE_SIGBUS; /* Disallow mremap */ } #else /* __OS_HAS_AGP */ static __inline__ struct page *drm_do_vm_nopage(struct vm_area_struct *vma, unsigned long address) { return NOPAGE_SIGBUS; } #endif /* __OS_HAS_AGP */ /** * \c nopage method for shared virtual memory. * * \param vma virtual memory area. * \param address access address. * \return pointer to the page structure. * * Get the the mapping, find the real physical page to map, get the page, and * return it. */ static __inline__ struct page *drm_do_vm_shm_nopage(struct vm_area_struct *vma, unsigned long address) { drm_map_t *map = (drm_map_t *) vma->vm_private_data; unsigned long offset; unsigned long i; struct page *page; if (address > vma->vm_end) return NOPAGE_SIGBUS; /* Disallow mremap */ if (!map) return NOPAGE_OOM; /* Nothing allocated */ offset = address - vma->vm_start; i = (unsigned long)map->handle + offset; page = (map->type == _DRM_CONSISTENT) ? virt_to_page((void *)i) : vmalloc_to_page((void *)i); if (!page) return NOPAGE_OOM; get_page(page); DRM_DEBUG("shm_nopage 0x%lx\n", address); return page; } /** * \c close method for shared virtual memory. * * \param vma virtual memory area. * * Deletes map information if we are the last * person to close a mapping and it's not in the global maplist. */ void drm_vm_shm_close(struct vm_area_struct *vma) { drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_vma_entry_t *pt, *prev, *next; drm_map_t *map; drm_map_list_t *r_list; struct list_head *list; int found_maps = 0; DRM_DEBUG("0x%08lx,0x%08lx\n", vma->vm_start, vma->vm_end - vma->vm_start); atomic_dec(&dev->vma_count); map = vma->vm_private_data; down(&dev->struct_sem); for (pt = dev->vmalist, prev = NULL; pt; pt = next) { next = pt->next; if (pt->vma->vm_private_data == map) found_maps++; if (pt->vma == vma) { if (prev) { prev->next = pt->next; } else { dev->vmalist = pt->next; } drm_free(pt, sizeof(*pt), DRM_MEM_VMAS); } else { prev = pt; } } /* We were the only map that was found */ if (found_maps == 1 && map->flags & _DRM_REMOVABLE) { /* Check to see if we are in the maplist, if we are not, then * we delete this mappings information. */ found_maps = 0; list = &dev->maplist->head; list_for_each(list, &dev->maplist->head) { r_list = list_entry(list, drm_map_list_t, head); if (r_list->map == map) found_maps++; } if (!found_maps) { switch (map->type) { case _DRM_REGISTERS: case _DRM_FRAME_BUFFER: if (drm_core_has_MTRR(dev) && map->mtrr >= 0) { int retcode; retcode = mtrr_del(map->mtrr, map->offset, map->size); DRM_DEBUG("mtrr_del = %d\n", retcode); } drm_ioremapfree(map->handle, map->size, dev); break; case _DRM_SHM: vfree(map->handle); break; case _DRM_AGP: case _DRM_SCATTER_GATHER: break; case _DRM_CONSISTENT: drm_pci_free(dev, map->size, map->handle, map->offset); break; } drm_free(map, sizeof(*map), DRM_MEM_MAPS); } } up(&dev->struct_sem); } /** * \c nopage method for DMA virtual memory. * * \param vma virtual memory area. * \param address access address. * \return pointer to the page structure. * * Determine the page number from the page offset and get it from drm_device_dma::pagelist. */ static __inline__ struct page *drm_do_vm_dma_nopage(struct vm_area_struct *vma, unsigned long address) { drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_device_dma_t *dma = dev->dma; unsigned long offset; unsigned long page_nr; struct page *page; if (!dma) return NOPAGE_SIGBUS; /* Error */ if (address > vma->vm_end) return NOPAGE_SIGBUS; /* Disallow mremap */ if (!dma->pagelist) return NOPAGE_OOM; /* Nothing allocated */ offset = address - vma->vm_start; /* vm_[pg]off[set] should be 0 */ page_nr = offset >> PAGE_SHIFT; page = virt_to_page((dma->pagelist[page_nr] + (offset & (~PAGE_MASK)))); get_page(page); DRM_DEBUG("dma_nopage 0x%lx (page %lu)\n", address, page_nr); return page; } /** * \c nopage method for scatter-gather virtual memory. * * \param vma virtual memory area. * \param address access address. * \return pointer to the page structure. * * Determine the map offset from the page offset and get it from drm_sg_mem::pagelist. */ static __inline__ struct page *drm_do_vm_sg_nopage(struct vm_area_struct *vma, unsigned long address) { drm_map_t *map = (drm_map_t *) vma->vm_private_data; drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_sg_mem_t *entry = dev->sg; unsigned long offset; unsigned long map_offset; unsigned long page_offset; struct page *page; if (!entry) return NOPAGE_SIGBUS; /* Error */ if (address > vma->vm_end) return NOPAGE_SIGBUS; /* Disallow mremap */ if (!entry->pagelist) return NOPAGE_OOM; /* Nothing allocated */ offset = address - vma->vm_start; map_offset = map->offset - dev->sg->handle; page_offset = (offset >> PAGE_SHIFT) + (map_offset >> PAGE_SHIFT); page = entry->pagelist[page_offset]; get_page(page); return page; } #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,0) static struct page *drm_vm_nopage(struct vm_area_struct *vma, unsigned long address, int *type) { if (type) *type = VM_FAULT_MINOR; return drm_do_vm_nopage(vma, address); } static struct page *drm_vm_shm_nopage(struct vm_area_struct *vma, unsigned long address, int *type) { if (type) *type = VM_FAULT_MINOR; return drm_do_vm_shm_nopage(vma, address); } static struct page *drm_vm_dma_nopage(struct vm_area_struct *vma, unsigned long address, int *type) { if (type) *type = VM_FAULT_MINOR; return drm_do_vm_dma_nopage(vma, address); } static struct page *drm_vm_sg_nopage(struct vm_area_struct *vma, unsigned long address, int *type) { if (type) *type = VM_FAULT_MINOR; return drm_do_vm_sg_nopage(vma, address); } #else /* LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,0) */ static struct page *drm_vm_nopage(struct vm_area_struct *vma, unsigned long address, int unused) { return drm_do_vm_nopage(vma, address); } static struct page *drm_vm_shm_nopage(struct vm_area_struct *vma, unsigned long address, int unused) { return drm_do_vm_shm_nopage(vma, address); } static struct page *drm_vm_dma_nopage(struct vm_area_struct *vma, unsigned long address, int unused) { return drm_do_vm_dma_nopage(vma, address); } static struct page *drm_vm_sg_nopage(struct vm_area_struct *vma, unsigned long address, int unused) { return drm_do_vm_sg_nopage(vma, address); } #endif /** AGP virtual memory operations */ static struct vm_operations_struct drm_vm_ops = { .nopage = drm_vm_nopage, .open = drm_vm_open, .close = drm_vm_close, }; /** Shared virtual memory operations */ static struct vm_operations_struct drm_vm_shm_ops = { .nopage = drm_vm_shm_nopage, .open = drm_vm_open, .close = drm_vm_shm_close, }; /** DMA virtual memory operations */ static struct vm_operations_struct drm_vm_dma_ops = { .nopage = drm_vm_dma_nopage, .open = drm_vm_open, .close = drm_vm_close, }; /** Scatter-gather virtual memory operations */ static struct vm_operations_struct drm_vm_sg_ops = { .nopage = drm_vm_sg_nopage, .open = drm_vm_open, .close = drm_vm_close, }; /** * \c open method for shared virtual memory. * * \param vma virtual memory area. * * Create a new drm_vma_entry structure as the \p vma private data entry and * add it to drm_device::vmalist. */ void drm_vm_open(struct vm_area_struct *vma) { drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_vma_entry_t *vma_entry; DRM_DEBUG("0x%08lx,0x%08lx\n", vma->vm_start, vma->vm_end - vma->vm_start); atomic_inc(&dev->vma_count); vma_entry = drm_alloc(sizeof(*vma_entry), DRM_MEM_VMAS); if (vma_entry) { down(&dev->struct_sem); vma_entry->vma = vma; vma_entry->next = dev->vmalist; vma_entry->pid = current->pid; dev->vmalist = vma_entry; up(&dev->struct_sem); } } /** * \c close method for all virtual memory types. * * \param vma virtual memory area. * * Search the \p vma private data entry in drm_device::vmalist, unlink it, and * free it. */ void drm_vm_close(struct vm_area_struct *vma) { drm_file_t *priv = vma->vm_file->private_data; drm_device_t *dev = priv->head->dev; drm_vma_entry_t *pt, *prev; DRM_DEBUG("0x%08lx,0x%08lx\n", vma->vm_start, vma->vm_end - vma->vm_start); atomic_dec(&dev->vma_count); down(&dev->struct_sem); for (pt = dev->vmalist, prev = NULL; pt; prev = pt, pt = pt->next) { if (pt->vma == vma) { if (prev) { prev->next = pt->next; } else { dev->vmalist = pt->next; } drm_free(pt, sizeof(*pt), DRM_MEM_VMAS); break; } } up(&dev->struct_sem); } /** * mmap DMA memory. * * \param filp file pointer. * \param vma virtual memory area. * \return zero on success or a negative number on failure. * * Sets the virtual memory area operations structure to vm_dma_ops, the file * pointer, and calls vm_open(). */ int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma) { drm_file_t *priv = filp->private_data; drm_device_t *dev; drm_device_dma_t *dma; unsigned long length = vma->vm_end - vma->vm_start; lock_kernel(); dev = priv->head->dev; dma = dev->dma; DRM_DEBUG("start = 0x%lx, end = 0x%lx, offset = 0x%lx\n", vma->vm_start, vma->vm_end, VM_OFFSET(vma)); /* Length must match exact page count */ if (!dma || (length >> PAGE_SHIFT) != dma->page_count) { unlock_kernel(); return -EINVAL; } unlock_kernel(); vma->vm_ops = &drm_vm_dma_ops; #if LINUX_VERSION_CODE <= 0x02040e /* KERNEL_VERSION(2,4,14) */ vma->vm_flags |= VM_LOCKED | VM_SHM; /* Don't swap */ #else vma->vm_flags |= VM_RESERVED; /* Don't swap */ #endif vma->vm_file = filp; /* Needed for drm_vm_open() */ drm_vm_open(vma); return 0; } unsigned long drm_core_get_map_ofs(drm_map_t * map) { return map->offset; } EXPORT_SYMBOL(drm_core_get_map_ofs); unsigned long drm_core_get_reg_ofs(struct drm_device *dev) { #ifdef __alpha__ return dev->hose->dense_mem_base - dev->hose->mem_space->start; #else return 0; #endif } EXPORT_SYMBOL(drm_core_get_reg_ofs); /** * mmap DMA memory. * * \param filp file pointer. * \param vma virtual memory area. * \return zero on success or a negative number on failure. * * If the virtual memory area has no offset associated with it then it's a DMA * area, so calls mmap_dma(). Otherwise searches the map in drm_device::maplist, * checks that the restricted flag is not set, sets the virtual memory operations * according to the mapping type and remaps the pages. Finally sets the file * pointer and calls vm_open(). */ int drm_mmap(struct file *filp, struct vm_area_struct *vma) { drm_file_t *priv = filp->private_data; drm_device_t *dev = priv->head->dev; drm_map_t *map = NULL; drm_map_list_t *r_list; unsigned long offset = 0; struct list_head *list; DRM_DEBUG("start = 0x%lx, end = 0x%lx, offset = 0x%lx\n", vma->vm_start, vma->vm_end, VM_OFFSET(vma)); if (!priv->authenticated) return -EACCES; /* We check for "dma". On Apple's UniNorth, it's valid to have * the AGP mapped at physical address 0 * --BenH. */ if (!VM_OFFSET(vma) #if __OS_HAS_AGP && (!dev->agp || dev->agp->agp_info.device->vendor != PCI_VENDOR_ID_APPLE) #endif ) return drm_mmap_dma(filp, vma); /* A sequential search of a linked list is fine here because: 1) there will only be about 5-10 entries in the list and, 2) a DRI client only has to do this mapping once, so it doesn't have to be optimized for performance, even if the list was a bit longer. */ list_for_each(list, &dev->maplist->head) { unsigned long off; r_list = list_entry(list, drm_map_list_t, head); map = r_list->map; if (!map) continue; off = dev->driver->get_map_ofs(map); if (off == VM_OFFSET(vma)) break; } if (!map || ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) return -EPERM; /* Check for valid size. */ if (map->size < vma->vm_end - vma->vm_start) return -EINVAL; if (!capable(CAP_SYS_ADMIN) && (map->flags & _DRM_READ_ONLY)) { vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE); #if defined(__i386__) || defined(__x86_64__) pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW; #else /* Ye gads this is ugly. With more thought we could move this up higher and use `protection_map' instead. */ vma->vm_page_prot = __pgprot(pte_val (pte_wrprotect (__pte(pgprot_val(vma->vm_page_prot))))); #endif } switch (map->type) { case _DRM_AGP: if (drm_core_has_AGP(dev) && dev->agp->cant_use_aperture) { /* * On some platforms we can't talk to bus dma address from the CPU, so for * memory of type DRM_AGP, we'll deal with sorting out the real physical * pages and mappings in nopage() */ #if defined(__powerpc__) pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE; #endif vma->vm_ops = &drm_vm_ops; break; } /* fall through to _DRM_FRAME_BUFFER... */ case _DRM_FRAME_BUFFER: case _DRM_REGISTERS: if (VM_OFFSET(vma) >= __pa(high_memory)) { #if defined(__i386__) || defined(__x86_64__) if (boot_cpu_data.x86 > 3 && map->type != _DRM_AGP) { pgprot_val(vma->vm_page_prot) |= _PAGE_PCD; pgprot_val(vma->vm_page_prot) &= ~_PAGE_PWT; } #elif defined(__powerpc__) pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE | _PAGE_GUARDED; #endif vma->vm_flags |= VM_IO; /* not in core dump */ } #if defined(__ia64__) if (map->type != _DRM_AGP) vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); #endif offset = dev->driver->get_reg_ofs(dev); #ifdef __sparc__ if (io_remap_page_range(DRM_RPR_ARG(vma) vma->vm_start, VM_OFFSET(vma) + offset, vma->vm_end - vma->vm_start, vma->vm_page_prot, 0)) #else if (remap_pfn_range(vma, vma->vm_start, (VM_OFFSET(vma) + offset) >> PAGE_SHIFT, vma->vm_end - vma->vm_start, vma->vm_page_prot)) #endif return -EAGAIN; DRM_DEBUG(" Type = %d; start = 0x%lx, end = 0x%lx," " offset = 0x%lx\n", map->type, vma->vm_start, vma->vm_end, VM_OFFSET(vma) + offset); vma->vm_ops = &drm_vm_ops; break; case _DRM_SHM: case _DRM_CONSISTENT: /* Consistent memory is much like shared memory. The * only difference is that drm_vm_shm_nopage must use * virt_to_page instead of vmalloc_to_page. */ vma->vm_ops = &drm_vm_shm_ops; vma->vm_private_data = (void *)map; /* Don't let this area swap. Change when DRM_KERNEL advisory is supported. */ #if LINUX_VERSION_CODE <= 0x02040e /* KERNEL_VERSION(2,4,14) */ vma->vm_flags |= VM_LOCKED; #else vma->vm_flags |= VM_RESERVED; #endif break; case _DRM_SCATTER_GATHER: vma->vm_ops = &drm_vm_sg_ops; vma->vm_private_data = (void *)map; #if LINUX_VERSION_CODE <= 0x02040e /* KERNEL_VERSION(2,4,14) */ vma->vm_flags |= VM_LOCKED; #else vma->vm_flags |= VM_RESERVED; #endif break; default: return -EINVAL; /* This should never happen. */ } #if LINUX_VERSION_CODE <= 0x02040e /* KERNEL_VERSION(2,4,14) */ vma->vm_flags |= VM_LOCKED | VM_SHM; /* Don't swap */ #else vma->vm_flags |= VM_RESERVED; /* Don't swap */ #endif vma->vm_file = filp; /* Needed for drm_vm_open() */ drm_vm_open(vma); return 0; } EXPORT_SYMBOL(drm_mmap); > 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 
/* drm_context.h -- IOCTLs for generic contexts -*- linux-c -*-
 * Created: Fri Nov 24 18:31:37 2000 by gareth@valinux.com
 *
 * Copyright 1999, 2000 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Rickard E. (Rik) Faith <faith@valinux.com>
 *    Gareth Hughes <gareth@valinux.com>
 */

#define __NO_VERSION__
#include "drmP.h"

#if __HAVE_CTX_BITMAP

/* ================================================================
 * Context bitmap support
 */

void DRM(ctxbitmap_free)( drm_device_t *dev, int ctx_handle )
{
	if ( ctx_handle < 0 ) goto failed;
	if ( !dev->ctx_bitmap ) goto failed;

	if ( ctx_handle < DRM_MAX_CTXBITMAP ) {
		DRM_OS_LOCK;
		clear_bit( ctx_handle, dev->ctx_bitmap );
		dev->context_sareas[ctx_handle] = NULL;
		DRM_OS_UNLOCK;
		return;
	}
failed:
       	DRM_ERROR( "Attempt to free invalid context handle: %d\n",
		   ctx_handle );
       	return;
}

int DRM(ctxbitmap_next)( drm_device_t *dev )
{
	int bit;

	if(!dev->ctx_bitmap) return -1;

	DRM_OS_LOCK;
	bit = find_first_zero_bit( dev->ctx_bitmap, DRM_MAX_CTXBITMAP );
	if ( bit < DRM_MAX_CTXBITMAP ) {
		set_bit( bit, dev->ctx_bitmap );
	   	DRM_DEBUG( "drm_ctxbitmap_next bit : %d\n", bit );
		if((bit+1) > dev->max_context) {
			dev->max_context = (bit+1);
			if(dev->context_sareas) {
				drm_map_t **ctx_sareas;

				ctx_sareas = DRM(realloc)(dev->context_sareas,
						(dev->max_context - 1) * 
						sizeof(*dev->context_sareas),
						dev->max_context * 
						sizeof(*dev->context_sareas),
						DRM_MEM_MAPS);
				if(!ctx_sareas) {
					clear_bit(bit, dev->ctx_bitmap);
					DRM_OS_UNLOCK;
					return -1;
				}
				dev->context_sareas = ctx_sareas;
				dev->context_sareas[bit] = NULL;
			} else {
				/* max_context == 1 at this point */
				dev->context_sareas = DRM(alloc)(
						dev->max_context * 
						sizeof(*dev->context_sareas),
						DRM_MEM_MAPS);
				if(!dev->context_sareas) {
					clear_bit(bit, dev->ctx_bitmap);
					DRM_OS_UNLOCK;
					return -1;
				}
				dev->context_sareas[bit] = NULL;
			}
		}
		DRM_OS_UNLOCK;
		return bit;
	}
	DRM_OS_UNLOCK;
	return -1;
}

int DRM(ctxbitmap_init)( drm_device_t *dev )
{
	int i;
   	int temp;

	DRM_OS_LOCK;
	dev->ctx_bitmap = (unsigned long *) DRM(alloc)( PAGE_SIZE,
							DRM_MEM_CTXBITMAP );
	if ( dev->ctx_bitmap == NULL ) {
		DRM_OS_UNLOCK;
		DRM_OS_RETURN(ENOMEM);
	}
	memset( (void *)dev->ctx_bitmap, 0, PAGE_SIZE );
	dev->context_sareas = NULL;
	dev->max_context = -1;
	DRM_OS_UNLOCK;

	for ( i = 0 ; i < DRM_RESERVED_CONTEXTS ; i++ ) {
		temp = DRM(ctxbitmap_next)( dev );
	   	DRM_DEBUG( "drm_ctxbitmap_init : %d\n", temp );
	}

	return 0;
}

void DRM(ctxbitmap_cleanup)( drm_device_t *dev )
{
	DRM_OS_LOCK;
	if( dev->context_sareas ) DRM(free)( dev->context_sareas,
					     sizeof(*dev->context_sareas) * 
					     dev->max_context,
					     DRM_MEM_MAPS );
	DRM(free)( (void *)dev->ctx_bitmap, PAGE_SIZE, DRM_MEM_CTXBITMAP );
	DRM_OS_UNLOCK;
}

/* ================================================================
 * Per Context SAREA Support
 */

int DRM(getsareactx)( DRM_OS_IOCTL )
{
	DRM_OS_DEVICE;
	drm_ctx_priv_map_t request;
	drm_map_t *map;

	DRM_OS_KRNFROMUSR( request, (drm_ctx_priv_map_t *)data, 
			   sizeof(request) );

	DRM_OS_LOCK;
	if (dev->max_context < 0 || request.ctx_id >= (unsigned) dev->max_context) {
		DRM_OS_UNLOCK;
		DRM_OS_RETURN(EINVAL);
	}

	map = dev->context_sareas[request.ctx_id];
	DRM_OS_UNLOCK;

	request.handle = map->handle;

	DRM_OS_KRNTOUSR( (drm_ctx_priv_map_t *)data, request, sizeof(request) );

	return 0;
}

int DRM(setsareactx)( DRM_OS_IOCTL )
{
	DRM_OS_DEVICE;
	drm_ctx_priv_map_t request;
	drm_map_t *map = NULL;
	drm_map_list_entry_t *list;

	DRM_OS_KRNFROMUSR( request, (drm_ctx_priv_map_t *)data,
			   sizeof(request) );

	DRM_OS_LOCK;
	TAILQ_FOREACH(list, dev->maplist, link) {
		map=list->map;
		if(map->handle == request.handle) 
			goto found;
	}

bad:
	DRM_OS_UNLOCK;
	return -EINVAL;

found:
	map = list->map;
	if (!map) goto bad;
	if (dev->max_context < 0)
		goto bad;
	if (request.ctx_id >= (unsigned) dev->max_context)
		goto bad;
	dev->context_sareas[request.ctx_id] = map;
	DRM_OS_UNLOCK;
	return 0;
}

/* ================================================================
 * The actual DRM context handling routines
 */

int DRM(context_switch)( drm_device_t *dev, int old, int new )
{
        char buf[64];

        if ( test_and_set_bit( 0, &dev->context_flag ) ) {
                DRM_ERROR( "Reentering -- FIXME\n" );
                DRM_OS_RETURN(EBUSY);
        }

#if __HAVE_DMA_HISTOGRAM
        dev->ctx_start = get_cycles();
#endif

        DRM_DEBUG( "Context switch from %d to %d\n", old, new );

        if ( new == dev->last_context ) {
                clear_bit( 0, &dev->context_flag );
                return 0;
        }

        if ( DRM(flags) & DRM_FLAG_NOCTX ) {
                DRM(context_switch_complete)( dev, new );
        } else {