From: Franck Bui-Huu Date: Thu, 12 Oct 2006 19:06:33 +0000 (+0200) Subject: [PATCH] Fix up mmap_kmem X-Git-Tag: firefly_0821_release~32062 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=99a10a60ba9bedcf5d70ef81414d3e03816afa3f;p=firefly-linux-kernel-4.4.55.git [PATCH] Fix up mmap_kmem vma->vm_pgoff is an pfn _offset_ relatif to the begining of the memory start. The previous code was doing at first: vma->vm_pgoff << PAGE_SHIFT which results into a wrong physical address since some platforms have a physical mem start that can be different from 0. After that the previous call __pa() on this wrong physical address, however __pa() is used to convert a _virtual_ address into a physical one. This patch rewrites this convertion. It calculates the pfn of PAGE_OFFSET which is the pfn of the mem start then it adds the vma->vm_pgoff to it. It also uses virt_to_phys() instead of __pa() since the latter shouldn't be used by drivers. Signed-off-by: Franck Bui-Huu Signed-off-by: Linus Torvalds --- diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 6511012cbdcd..a89cb52228c2 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -292,8 +292,8 @@ static int mmap_kmem(struct file * file, struct vm_area_struct * vma) { unsigned long pfn; - /* Turn a kernel-virtual address into a physical page frame */ - pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT; + /* Turn a pfn offset into an absolute pfn */ + pfn = PFN_DOWN(virt_to_phys((void *)PAGE_OFFSET)) + vma->vm_pgoff; /* * RED-PEN: on some architectures there is more mapped memory