Function remap_pfn_range() means map physical address pfn<<PAGE_SHIFT to
user addr.
For nommu arch it's implemented by vma->vm_start = pfn << PAGE_SHIFT which is
wrong acroding the original meaning of this function.
Some driver developer using remap_pfn_range() with correct parameter will get
unexpected result because vm_start is changed.
It should be implementd just like addr = pfn << PAGE_SHIFT which is meanless
on nommu arch, so this patch just make it simply return 0.
Reported-by: Scott Jiang <scott.jiang.linux@xxxxxxxxx>
Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx>
---
include/linux/mm.h | 10 ++++++++++
mm/nommu.c | 8 --------
2 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9670f71..017c32f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1526,8 +1526,18 @@ static inline pgprot_t vm_get_page_prot(unsigned long vm_flags)
#endif
struct vm_area_struct *find_extend_vma(struct mm_struct *, unsigned long addr);
+
+#ifdef CONFIG_MMU
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t);
+#else
+static inline int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+ unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+ return 0;
+}
+#endif
+
int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn);
diff --git a/mm/nommu.c b/mm/nommu.c
index 1fd0c51..01cf6e0 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1813,14 +1813,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
return NULL;
}
-int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
- unsigned long to, unsigned long size, pgprot_t prot)
-{
- vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
- return 0;
-}
-EXPORT_SYMBOL(remap_pfn_range);
-
int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
unsigned long pgoff)
{
--
1.6.3.3
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