Nick Piggin wrote:
Add a vm_insert_pfn helper, so that ->fault handlers can have nopfn
functionality by installing their own pte and returning NULL.
Signed-off-by: Nick Piggin <[email protected]>
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -1121,6 +1121,7 @@ unsigned long vmalloc_to_pfn(void *addr)
int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
unsigned long pfn, unsigned long size, pgprot_t);
int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
+int vm_insert_pfn(struct vm_area_struct *, unsigned long addr, unsigned long pfn);
struct page *follow_page(struct vm_area_struct *, unsigned long address,
unsigned int foll_flags);
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1267,6 +1267,50 @@ int vm_insert_page(struct vm_area_struct
}
EXPORT_SYMBOL(vm_insert_page);
+/**
+ * vm_insert_pfn - insert single pfn into user vma
+ * @vma: user vma to map to
+ * @addr: target user address of this page
+ * @pfn: source kernel pfn
+ *
+ * Similar to vm_inert_page, this allows drivers to insert individual pages
+ * they've allocated into a user vma. Same comments apply.
+ *
+ * This function should only be called from a vm_ops->fault handler, and
+ * in that case the handler should return NULL.
+ */
+int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn)
Nick, I just realized: would it be possible to have a pgprot_t argument
to this one, instead of it using vma->vm_pgprot?
The motivation for this (DRM again) is that some architectures (powerpc)
cannot map the AGP aperture through IO space, but needs to remap the
page from memory with a nocache attribute set. Others need special
pgprot settings for write-combined mappings.
Now, there's a possibility to change vma->vm_pgprot during the first
->fault(), but again, we only have the mmap_sem in read mode.
/Thomas
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