linux-kernel - [PATCH] [29/50] mm/nommu.c: fix remap_pfn

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Date:	Thu, 28 Jul 2011 16:44:33 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	lliubbo@...il.com, geert@...ux-m68k.org, dhowells@...hat.com,
	gerg@...inux.org, vapier@...too.org, akpm@...ux-foundation.org,
	torvalds@...ux-foundation.org, ak@...ux.intel.com,
	linux-kernel@...r.kernel.org, stable@...nel.org,
	tim.bird@...sony.com
Subject: [PATCH] [29/50] mm/nommu.c: fix remap_pfn_range()

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Bob Liu <lliubbo@...il.com>

[ upstream commit 8f3b1327aa454bc8283e96bca7669c3c88b83f79 ]

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.  And some driver
developer using remap_pfn_range() with correct parameter will get
unexpected result because vm_start is changed.  It should be implementd
like addr = pfn << PAGE_SHIFT but which is meanless on nommu arch, this
patch just make it simply return.

Parameter name and setting of vma->vm_flags also be fixed.

Signed-off-by: Bob Liu <lliubbo@...il.com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: David Howells <dhowells@...hat.com>
Acked-by: Greg Ungerer <gerg@...inux.org>
Cc: Mike Frysinger <vapier@...too.org>
Cc: Bob Liu <lliubbo@...il.com>
Cc: <stable@...nel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

Index: linux-2.6.35.y/mm/nommu.c
===================================================================
--- linux-2.6.35.y.orig/mm/nommu.c
+++ linux-2.6.35.y/mm/nommu.c
@@ -1747,10 +1747,13 @@ struct page *follow_page(struct vm_area_
 	return NULL;
 }
 
-int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
-		unsigned long to, unsigned long size, pgprot_t prot)
+int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
+		unsigned long pfn, unsigned long size, pgprot_t prot)
 {
-	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
+	if (addr != (pfn << PAGE_SHIFT))
+		return -EINVAL;
+
+	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
 	return 0;
 }
 EXPORT_SYMBOL(remap_pfn_range);
--
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