• Matt Fleming's avatar
    x86, efi: Calling __pa() with an ioremap()ed address is invalid · e8c71062
    Matt Fleming authored
    If we encounter an efi_memory_desc_t without EFI_MEMORY_WB set
    in ->attribute we currently call set_memory_uc(), which in turn
    calls __pa() on a potentially ioremap'd address.
    
    On CONFIG_X86_32 this is invalid, resulting in the following
    oops on some machines:
    
      BUG: unable to handle kernel paging request at f7f22280
      IP: [<c10257b9>] reserve_ram_pages_type+0x89/0x210
      [...]
    
      Call Trace:
       [<c104f8ca>] ? page_is_ram+0x1a/0x40
       [<c1025aff>] reserve_memtype+0xdf/0x2f0
       [<c1024dc9>] set_memory_uc+0x49/0xa0
       [<c19334d0>] efi_enter_virtual_mode+0x1c2/0x3aa
       [<c19216d4>] start_kernel+0x291/0x2f2
       [<c19211c7>] ? loglevel+0x1b/0x1b
       [<c19210bf>] i386_start_kernel+0xbf/0xc8
    
    A better approach to this problem is to map the memory region
    with the correct attributes from the start, instead of modifying
    it after the fact. The uncached case can be handled by
    ioremap_nocache() and the cached by ioremap_cache().
    
    Despite first impressions, it's not possible to use
    ioremap_cache() to map all cached memory regions on
    CONFIG_X86_64 because EFI_RUNTIME_SERVICES_DATA regions really
    don't like being mapped into the vmalloc space, as detailed in
    the following bug report,
    
    	https://bugzilla.redhat.com/show_bug.cgi?id=748516
    
    Therefore, we need to ensure that any EFI_RUNTIME_SERVICES_DATA
    regions are covered by the direct kernel mapping table on
    CONFIG_X86_64. To accomplish this we now map E820_RESERVED_EFI
    regions via the direct kernel mapping with the initial call to
    init_memory_mapping() in setup_arch(), whereas previously these
    regions wouldn't be mapped if they were after the last E820_RAM
    region until efi_ioremap() was called. Doing it this way allows
    us to delete efi_ioremap() completely.
    Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Matthew Garrett <mjg@redhat.com>
    Cc: Zhang Rui <rui.zhang@intel.com>
    Cc: Huang Ying <huang.ying.caritas@gmail.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Link: http://lkml.kernel.org/r/1321621751-3650-1-git-send-email-matt@console-pimps.orgSigned-off-by: default avatarIngo Molnar <mingo@elte.hu>
    e8c71062
efi.h 4.01 KB