• James Hogan's avatar
    MIPS: KVM: Move commpage so 0x0 is unmapped · 42aa12e7
    James Hogan authored
    The comm page which is mapped into the guest kernel address space at
    0x0 has the unfortunate side effect of allowing guest kernel NULL
    pointer dereferences to succeed. The only constraint on this address is
    that it must be within 32KiB of 0x0, so that single lw/sw instructions
    (which have 16-bit signed offset fields) can be used to access it, using
    the zero register as a base.
    
    So lets move the comm page as high as possible within that constraint so
    that 0x0 can be left unmapped, at least for page sizes < 32KiB.
    Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Radim Krčmář <rkrcmar@redhat.com>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: linux-mips@linux-mips.org
    Cc: kvm@vger.kernel.org
    Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    42aa12e7
commpage.c 886 Bytes