nommu: provide follow_pfn(). (dfc2f91a) · Commits · 戴 / test

With the introduction of follow_pfn() as an exported symbol, modules have begun making use of it. Unfortunately this was not reflected on nommu at the time, so the in-tree users have subsequently all blown up with link errors there. This provides a simple follow_pfn() that just returns addr >> PAGE_SHIFT, which will do the right thing on nommu. There is no need to do range checking within the vma, as the find_vma() case will already take care of this. Signed-off-by:

Paul Mundt <lethal@linux-sh.org>

mm/nommu.c

+21 −0

Original line number	Diff line number	Diff line
		@@ -240,6 +240,27 @@ int get_user_pages(struct task_struct tsk, struct mm_struct mm,
		}
		EXPORT_SYMBOL(get_user_pages);

		/**
		* follow_pfn - look up PFN at a user virtual address
		* @vma: memory mapping
		* @address: user virtual address
		* @pfn: location to store found PFN
		*
		* Only IO mappings and raw PFN mappings are allowed.
		*
		* Returns zero and the pfn at @pfn on success, -ve otherwise.
		*/
		int follow_pfn(struct vm_area_struct *vma, unsigned long address,
		unsigned long *pfn)
		{
		if (!(vma->vm_flags & (VM_IO \| VM_PFNMAP)))
		return -EINVAL;

		*pfn = address >> PAGE_SHIFT;
		return 0;
		}
		EXPORT_SYMBOL(follow_pfn);

		DEFINE_RWLOCK(vmlist_lock);
		struct vm_struct *vmlist;

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