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    Subject[PATCH 3/3] x86/mce: Drop copyin special case for #MC
    Date
    Fixes to the iterator code to handle faults that are not on
    page boundaries mean that the special case for machine check
    during copy from user is no longer needed.

    Signed-off-by: Tony Luck <tony.luck@intel.com>
    ---
    arch/x86/lib/copy_user_64.S | 13 -------------
    1 file changed, 13 deletions(-)

    diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
    index 57b79c577496..2797e630b9b1 100644
    --- a/arch/x86/lib/copy_user_64.S
    +++ b/arch/x86/lib/copy_user_64.S
    @@ -234,24 +234,11 @@ EXPORT_SYMBOL(copy_user_enhanced_fast_string)
    */
    SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail)
    movl %edx,%ecx
    - cmp $X86_TRAP_MC,%eax /* check if X86_TRAP_MC */
    - je 3f
    1: rep movsb
    2: mov %ecx,%eax
    ASM_CLAC
    ret

    - /*
    - * Return zero to pretend that this copy succeeded. This
    - * is counter-intuitive, but needed to prevent the code
    - * in lib/iov_iter.c from retrying and running back into
    - * the poison cache line again. The machine check handler
    - * will ensure that a SIGBUS is sent to the task.
    - */
    -3: xorl %eax,%eax
    - ASM_CLAC
    - ret
    -
    _ASM_EXTABLE_CPY(1b, 2b)
    SYM_CODE_END(.Lcopy_user_handle_tail)

    --
    2.29.2
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