• Tejun Heo's avatar
    x86: make percpu symbols zerobased on SMP · 3e5d8f97
    Tejun Heo authored
    [ Based on original patch from Christoph Lameter and Mike Travis. ]
    This patch makes percpu symbols zerobased on x86_64 SMP by adding
    PERCPU_VADDR() to vmlinux.lds.h which helps setting explicit vaddr on
    the percpu output section and using it in vmlinux_64.lds.S.  A new
    PHDR is added as existing ones cannot contain sections near address
    zero.  PERCPU_VADDR() also adds a new symbol __per_cpu_load which
    always points to the vaddr of the loaded percpu data.init region.
    The following adjustments have been made to accomodate the address
    * code to locate percpu gdt_page in head_64.S is updated to add the
      load address to the gdt_page offset.
    * __per_cpu_load is used in places where access to the init data area
      is necessary.
    * pda->data_offset is initialized soon after C code is entered as zero
      value doesn't work anymore.
    This patch is mostly taken from Mike Travis' "x86_64: Base percpu
    variables at zero" patch.
    Signed-off-by: default avatarTejun Heo <tj@kernel.org>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
head64.c 3.8 KB