[lkml]   [2009]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    Patch in this message
    Subject[patch 31/71] x86: Fix fixmap page order for FIX_TEXT_POKE0,1
    2.6.30-stable review patch.  If anyone has any objections, please let us know.


    From: Mathieu Desnoyers <>

    commit 12b9d7ccb841805e347fec8f733f368f43ddba40 upstream.

    Masami reported:

    > Since the fixmap pages are assigned higher address to lower,
    > text_poke() has to use it with inverted order (FIX_TEXT_POKE1
    > to FIX_TEXT_POKE0).

    I prefer to just invert the order of the fixmap declaration.
    It's simpler and more straightforward.

    Backward fixmaps seems to be used by both x86 32 and 64.

    It's really rare but a nasty bug, because it only hurts when
    instructions to patch are crossing a page boundary. If this
    happens, the fixmap write accesses will spill on the following
    fixmap, which may very well crash the system. And this does not
    crash the system, it could leave illegal instructions in place.
    Thanks Masami for finding this.

    It seems to have crept into the 2.6.30-rc series, so this calls
    for a -stable inclusion.

    Signed-off-by: Mathieu Desnoyers <>
    Acked-by: Masami Hiramatsu <>
    LKML-Reference: <20090701213722.GH19926@Krystal>
    Signed-off-by: Ingo Molnar <>
    Signed-off-by: Greg Kroah-Hartman <>

    arch/x86/include/asm/fixmap.h | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/arch/x86/include/asm/fixmap.h
    +++ b/arch/x86/include/asm/fixmap.h
    @@ -111,8 +111,8 @@ enum fixed_addresses {
    - FIX_TEXT_POKE0, /* reserve 2 pages for text_poke() */
    + FIX_TEXT_POKE1, /* reserve 2 pages for text_poke() */
    + FIX_TEXT_POKE0, /* first page is last, because allocation is backward */
    * 256 temporary boot-time mappings, used by early_ioremap(),

     \ /
      Last update: 2009-07-29 02:27    [W:0.064 / U:18.644 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site