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author | Paul Mundt <lethal@linux-sh.org> | 2009-06-26 04:31:57 +0900 |
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committer | Paul Mundt <lethal@linux-sh.org> | 2009-06-26 04:31:57 +0900 |
commit | dfc2f91ac29f5ef50e74bf15a1a6b6aa6b952e62 (patch) | |
tree | 0b3eb3ae6b7b21226cf8e1410aa6dd6d0e07a110 | |
parent | 1fbcf37128cc19bd67d9a736fb634dc444e907d7 (diff) | |
download | linux-dfc2f91ac29f5ef50e74bf15a1a6b6aa6b952e62.tar.bz2 |
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 <lethal@linux-sh.org>
-rw-r--r-- | mm/nommu.c | 21 |
1 files changed, 21 insertions, 0 deletions
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; |