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    SubjectRe: [PATCH] x86, AMD: Correct F15h IC aliasing issue
    On Tue, Jul 26, 2011 at 02:34:30PM -0400, Ingo Molnar wrote:
    >
    > * Borislav Petkov <bp@amd64.org> wrote:
    >
    > > Ok, I went and installed a Debian wheezy with gnome and started
    > > almost everything I could find in the startup menu. Kernel is 3.0
    > > with Linus' simpler fix.
    > >
    > > The attached file shows all libraries which would create aliases
    > > (i.e. 2 or more unique values for bits [14:12] along with the
    > > respective count) in the total of:
    > >
    > > Total r-xp mappings: 831, aliasing: 240 (0.289%)
    >
    > 28.9%, right?

    Yessir.

    > > For example, libc gets mapped into all possible slots for [14:12]
    > >
    > > Library [14:12] count
    > > ======= ======= =====
    > > /lib/libc-2.11.2.so
    > > 0 12
    > > 1 12
    > > 2 11
    > > 3 12
    > > 4 13
    > > 5 16
    > > 6 13
    > > 7 9
    > >
    > >
    > > and so on.
    >
    > Was this done with a stock kernel, or with the simple patch applied?

    with the simplest version of Linus' patch:

    diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
    index 1dab519..6b1094d 100644
    --- a/arch/x86/mm/mmap.c
    +++ b/arch/x86/mm/mmap.c
    @@ -90,6 +90,8 @@ static unsigned long mmap_rnd(void)
    rnd = (long)get_random_int() % (1<<8);
    else
    rnd = (long)(get_random_int() % (1<<28));
    +
    + rnd &= ~0x7;
    }
    return rnd << PAGE_SHIFT;
    }
    --
    Regards/Gruss,
    Boris.

    Advanced Micro Devices GmbH
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