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Commit 5f4352fb authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Jeremy Fitzhardinge
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Allocate and free vmalloc areas 



Allocate/release a chunk of vmalloc address space:
 alloc_vm_area reserves a chunk of address space, and makes sure all
 the pagetables are constructed for that address range - but no pages.

 free_vm_area releases the address space range.

Signed-off-by: default avatarJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: default avatarIan Pratt <ian.pratt@xensource.com>
Signed-off-by: default avatarChristian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: default avatarChris Wright <chrisw@sous-sol.org>
Cc: "Jan Beulich" <JBeulich@novell.com>
Cc: "Andi Kleen" <ak@muc.de>
parent bdef40a6

include/linux/vmalloc.h

+4 −0
Original line number Diff line number Diff line
@@ -70,6 +70,10 @@ extern int map_vm_area(struct vm_struct *area, pgprot_t prot, 
			struct page ***pages);

extern void unmap_kernel_range(unsigned long addr, unsigned long size);



/* Allocate/destroy a 'vmalloc' VM area. */

extern struct vm_struct *alloc_vm_area(size_t size);

extern void free_vm_area(struct vm_struct *area);



/*

 *	Internals.  Dont't use..

 */

mm/vmalloc.c

+53 −0
Original line number Diff line number Diff line
@@ -767,3 +767,56 @@ EXPORT_SYMBOL(remap_vmalloc_range); 
void  __attribute__((weak)) vmalloc_sync_all(void)

{

}





static int f(pte_t *pte, struct page *pmd_page, unsigned long addr, void *data)

{

	/* apply_to_page_range() does all the hard work. */

	return 0;

}



/**

 *	alloc_vm_area - allocate a range of kernel address space

 *	@size:		size of the area

 *	@returns:	NULL on failure, vm_struct on success

 *

 *	This function reserves a range of kernel address space, and

 *	allocates pagetables to map that range.  No actual mappings

 *	are created.  If the kernel address space is not shared

 *	between processes, it syncs the pagetable across all

 *	processes.

 */

struct vm_struct *alloc_vm_area(size_t size)

{

	struct vm_struct *area;



	area = get_vm_area(size, VM_IOREMAP);

	if (area == NULL)

		return NULL;



	/*

	 * This ensures that page tables are constructed for this region

	 * of kernel virtual address space and mapped into init_mm.

	 */

	if (apply_to_page_range(&init_mm, (unsigned long)area->addr,

				area->size, f, NULL)) {

		free_vm_area(area);

		return NULL;

	}



	/* Make sure the pagetables are constructed in process kernel

	   mappings */

	vmalloc_sync_all();



	return area;

}

EXPORT_SYMBOL_GPL(alloc_vm_area);



void free_vm_area(struct vm_struct *area)

{

	struct vm_struct *ret;

	ret = remove_vm_area(area->addr);

	BUG_ON(ret != area);

	kfree(area);

}

EXPORT_SYMBOL_GPL(free_vm_area);