Re: [PATCH v3 2/3] x86/entry: Clear registers for 64bit exceptions/interrupts

[Dominik Brodowski]

On Mon, Feb 05, 2018 at 05:18:11PM -0800, Dan Williams wrote:
> @@ -1178,6 +1180,7 @@ ENTRY(paranoid_entry)
>       cld
>       SAVE_C_REGS 8
>       SAVE_EXTRA_REGS 8
> +     CLEAR_REGS_NOSPEC
>       ENCODE_FRAME_POINTER 8
>       movl    $1, %ebx
>       movl    $MSR_GS_BASE, %ecx
> @@ -1185,7 +1188,6 @@ ENTRY(paranoid_entry)
>       testl   %edx, %edx
>       js      1f                              /* negative -> in kernel */
>       SWAPGS
> -     xorl    %ebx, %ebx

Here, %ebx will be filled with $1 (see code snipped above) *after* the
call to CLEAR_REGS_NOSPEC. That's what this line has been clearing in the
past. So I'm not sure whether this line should be removed.

Thanks,
        Dominik