On Wed, Jan 14, 2015 at 1:48 PM, Denys Vlasenko <[email protected]> wrote:
> RESTORE_EXTRA_REGS + RESTORE_C_REGS looks small, but it's
> a lot of instructions (fourteen). Let's reuse them.
>
> Signed-off-by: Denys Vlasenko <[email protected]>
> CC: Linus Torvalds <[email protected]>
> CC: Oleg Nesterov <[email protected]>
> CC: Borislav Petkov <[email protected]>
> CC: "H. Peter Anvin" <[email protected]>
> CC: Andy Lutomirski <[email protected]>
> CC: Frederic Weisbecker <[email protected]>
> CC: X86 ML <[email protected]>
> CC: Alexei Starovoitov <[email protected]>
> CC: Will Drewry <[email protected]>
> CC: Kees Cook <[email protected]>
> CC: [email protected]
> ---
>  arch/x86/kernel/entry_64.S | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index a21b5b3..f5e815e 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -1270,12 +1270,10 @@ ENTRY(paranoid_exit)
>         jnz paranoid_restore
>         TRACE_IRQS_IRETQ 0
>         SWAPGS_UNSAFE_STACK
> -       RESTORE_EXTRA_REGS
> -       RESTORE_C_REGS
> -       REMOVE_PT_GPREGS_FROM_STACK 8
> -       INTERRUPT_RETURN
> +       jmp paranoid_restore1
>  paranoid_restore:
>         TRACE_IRQS_IRETQ_DEBUG 0
> +paranoid_restore1:
>         RESTORE_EXTRA_REGS
>         RESTORE_C_REGS
>         REMOVE_PT_GPREGS_FROM_STACK 8

This is sort of a reply to the wrong thread, but wouldn't it be nicer
if we could pop a bunch of regs instead of using mov followed by add?
(Yes, this could be a followup, but it could be easier to spot now by
changing macros like RESTORE_XYZ.)

--Andy
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