• Josh Boyer's avatar
    x86, efi: Don't map Boot Services on i386 · 70087011
    Josh Boyer authored
    Add patch to fix 32bit EFI service mapping (rhbz 726701)
    
    Multiple people are reporting hitting the following WARNING on i386,
    
      WARNING: at arch/x86/mm/ioremap.c:102 __ioremap_caller+0x3d3/0x440()
      Modules linked in:
      Pid: 0, comm: swapper Not tainted 3.9.0-rc7+ #95
      Call Trace:
       [<c102b6af>] warn_slowpath_common+0x5f/0x80
       [<c1023fb3>] ? __ioremap_caller+0x3d3/0x440
       [<c1023fb3>] ? __ioremap_caller+0x3d3/0x440
       [<c102b6ed>] warn_slowpath_null+0x1d/0x20
       [<c1023fb3>] __ioremap_caller+0x3d3/0x440
       [<c106007b>] ? get_usage_chars+0xfb/0x110
       [<c102d937>] ? vprintk_emit+0x147/0x480
       [<c1418593>] ? efi_enter_virtual_mode+0x1e4/0x3de
       [<c102406a>] ioremap_cache+0x1a/0x20
       [<c1418593>] ? efi_enter_virtual_mode+0x1e4/0x3de
       [<c1418593>] efi_enter_virtual_mode+0x1e4/0x3de
       [<c1407984>] start_kernel+0x286/0x2f4
       [<c1407535>] ? repair_env_string+0x51/0x51
       [<c1407362>] i386_start_kernel+0x12c/0x12f
    
    Due to the workaround described in commit 916f676f ("x86, efi: Retain
    boot service code until after switching to virtual mode") EFI Boot
    Service regions are mapped for a period during boot. Unfortunately, with
    the limited size of the i386 direct kernel map it's possible that some
    of the Boot Service regions will not be directly accessible, which
    causes them to be ioremap()'d, triggering the above warning as the
    regions are marked as E820_RAM in the e820 memmap.
    
    There are currently only two situations where we need to map EFI Boot
    Service regions,
    
      1. To workaround the firmware bug described in 916f676f
      2. To access the ACPI BGRT image
    
    but since we haven't seen an i386 implementation that requires either,
    this simple fix should suffice for now.
    
    [ Added to changelog - Matt ]
    Reported-by: default avatarBryan O'Donoghue <bryan.odonoghue.lkml@nexus-software.ie>
    Acked-by: default avatarTom Zanussi <tom.zanussi@intel.com>
    Acked-by: default avatarDarren Hart <dvhart@linux.intel.com>
    Cc: Josh Triplett <josh@joshtriplett.org>
    Cc: Matthew Garrett <mjg59@srcf.ucam.org>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarJosh Boyer <jwboyer@redhat.com>
    Signed-off-by: default avatarMatt Fleming <matt.fleming@intel.com>
    70087011
efi.c 28.4 KB