Commit 574c5b3d authored by Thomas Hellstrom's avatar Thomas Hellstrom
Browse files

mm: Add a vmf_insert_mixed_prot() function 



The TTM module today uses a hack to be able to set a different page
protection than struct vm_area_struct::vm_page_prot. To be able to do
this properly, add the needed vm functionality as vmf_insert_mixed_prot().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: default avatarThomas Hellstrom <thellstrom@vmware.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 71e72740

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -2533,6 +2533,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, 
			unsigned long pfn, pgprot_t pgprot);

vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,

			pfn_t pfn);

vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,

			pfn_t pfn, pgprot_t pgprot);

vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,

		unsigned long addr, pfn_t pfn);

int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);

include/linux/mm_types.h

+6 −1
Original line number Diff line number Diff line
@@ -312,7 +312,12 @@ struct vm_area_struct { 
	/* Second cache line starts here. */



	struct mm_struct *vm_mm;	/* The address space we belong to. */

	pgprot_t vm_page_prot;		/* Access permissions of this VMA. */



	/*

	 * Access permissions of this VMA.

	 * See vmf_insert_mixed_prot() for discussion.

	 */

	pgprot_t vm_page_prot;

	unsigned long vm_flags;		/* Flags, see mm.h. */



	/*

mm/memory.c

+39 −4
Original line number Diff line number Diff line
@@ -1664,6 +1664,9 @@ out_unlock: 
 * vmf_insert_pfn_prot should only be used if using multiple VMAs is

 * impractical.

 *

 * See vmf_insert_mixed_prot() for a discussion of the implication of using

 * a value of @pgprot different from that of @vma->vm_page_prot.

 *

 * Context: Process context.  May allocate using %GFP_KERNEL.

 * Return: vm_fault_t value.

 */
@@ -1737,9 +1740,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn) 
}



static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,

		unsigned long addr, pfn_t pfn, bool mkwrite)

		unsigned long addr, pfn_t pfn, pgprot_t pgprot,

		bool mkwrite)

{

	pgprot_t pgprot = vma->vm_page_prot;

	int err;



	BUG_ON(!vm_mixed_ok(vma, pfn));
@@ -1782,10 +1785,42 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma, 
	return VM_FAULT_NOPAGE;

}



/**

 * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot

 * @vma: user vma to map to

 * @addr: target user address of this page

 * @pfn: source kernel pfn

 * @pgprot: pgprot flags for the inserted page

 *

 * This is exactly like vmf_insert_mixed(), except that it allows drivers to

 * to override pgprot on a per-page basis.

 *

 * Typically this function should be used by drivers to set caching- and

 * encryption bits different than those of @vma->vm_page_prot, because

 * the caching- or encryption mode may not be known at mmap() time.

 * This is ok as long as @vma->vm_page_prot is not used by the core vm

 * to set caching and encryption bits for those vmas (except for COW pages).

 * This is ensured by core vm only modifying these page table entries using

 * functions that don't touch caching- or encryption bits, using pte_modify()

 * if needed. (See for example mprotect()).

 * Also when new page-table entries are created, this is only done using the

 * fault() callback, and never using the value of vma->vm_page_prot,

 * except for page-table entries that point to anonymous pages as the result

 * of COW.

 *

 * Context: Process context.  May allocate using %GFP_KERNEL.

 * Return: vm_fault_t value.

 */

vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,

				 pfn_t pfn, pgprot_t pgprot)

{

	return __vm_insert_mixed(vma, addr, pfn, pgprot, false);

}



vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,

		pfn_t pfn)

{

	return __vm_insert_mixed(vma, addr, pfn, false);

	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);

}

EXPORT_SYMBOL(vmf_insert_mixed);
@@ -1797,7 +1832,7 @@ EXPORT_SYMBOL(vmf_insert_mixed); 
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,

		unsigned long addr, pfn_t pfn)

{

	return __vm_insert_mixed(vma, addr, pfn, true);

	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);

}

EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);

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