• Lennert Buytenhek's avatar
    [PATCH] make valid_mmap_phys_addr_range() take a pfn · 06c67bef
    Lennert Buytenhek authored
    Newer ARMs have a 40 bit physical address space, but mapping physical
    memory above 4G needs a special page table format which we (currently?) do
    not use for userspace mappings, so what happens instead is that mapping an
    address >= 4G will happily discard the upper bits and wrap.
    
    There is a valid_mmap_phys_addr_range() arch hook where we could check for
    >= 4G addresses and deny the mapping, but this hook takes an unsigned long
    address:
    
    	static inline int valid_mmap_phys_addr_range(unsigned long addr, size_t size);
    
    And drivers/char/mem.c:mmap_mem() calls it like this:
    
    	static int mmap_mem(struct file * file, struct vm_area_struct * vma)
    	{
    		size_t size = vma->vm_end - vma->vm_start;
    
    		if (!valid_mmap_phys_addr_range(vma->vm_pgoff << PAGE_SHIFT, size))
    
    So that's not much help either.
    
    This patch makes the hook take a pfn instead of a phys address.
    Signed-off-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
    Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
    Cc: "Luck, Tony" <tony.luck@intel.com>
    Cc: Russell King <rmk@arm.linux.org.uk>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    06c67bef
mem.c 20.8 KB