From dfc2f91ac29f5ef50e74bf15a1a6b6aa6b952e62 Mon Sep 17 00:00:00 2001 From: Paul Mundt Date: Fri, 26 Jun 2009 04:31:57 +0900 Subject: [PATCH] nommu: provide follow_pfn(). 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 --- mm/nommu.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/mm/nommu.c b/mm/nommu.c index 2fd2ad5da98e..598bc871487a 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -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; -- 2.39.2