Re: [Xen-devel] [PATCH 1/2, v2] x86: use MOV instead of PUSH/POP when saving/restoring register state

[Mats Petersson <mats.petersson@xxxxxxxxxx>]

On 30/10/12 14:27, Jan Beulich wrote:
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Acked-by: Keir Fraser <keir@xxxxxxx>
> ---
> This patch did not change from its v1 submission.
>
> --- a/xen/arch/x86/x86_64/compat/entry.S
> +++ b/xen/arch/x86/x86_64/compat/entry.S
> @@ -21,8 +21,7 @@ ENTRY(compat_hypercall)
>   UNLIKELY_START(ne, msi_check)
>           movl  $HYPERCALL_VECTOR,%edi
>           call  check_for_unexpected_msi
> -        RESTORE_ALL
> -        SAVE_ALL
> +        LOAD_C_CLOBBERED
>   UNLIKELY_END(msi_check)
>   
>           GET_CURRENT(%rbx)
> @@ -173,8 +172,7 @@ compat_bad_hypercall:
>   /* %rbx: struct vcpu, interrupts disabled */
>   compat_restore_all_guest:
>           ASSERT_INTERRUPTS_DISABLED
> -        RESTORE_ALL
> -        addq  $8,%rsp
> +        RESTORE_ALL adj=8
>   .Lft0:  iretq
>   
>   .section .fixup,"ax"
> --- a/xen/arch/x86/x86_64/entry.S
> +++ b/xen/arch/x86/x86_64/entry.S
> @@ -47,12 +47,10 @@ restore_all_guest:
>           cmpl  $1,%ecx
>           ja    .Lforce_iret
>   
> -        addq  $8,%rsp
> -        popq  %rcx                    # RIP
> -        popq  %r11                    # CS
> -        cmpw  $FLAT_USER_CS32,%r11
> -        popq  %r11                    # RFLAGS
> -        popq  %rsp                    # RSP
> +        cmpw  $FLAT_USER_CS32,16(%rsp)# CS
> +        movq  8(%rsp),%rcx            # RIP
> +        movq  24(%rsp),%r11           # RFLAGS
> +        movq  32(%rsp),%rsp           # RSP
>           je    1f
>           sysretq
>   1:      sysretl
> @@ -101,8 +99,7 @@ failsafe_callback:
>           ALIGN
>   /* No special register assumptions. */
>   restore_all_xen:
> -        RESTORE_ALL
> -        addq  $8,%rsp
> +        RESTORE_ALL adj=8
>           iretq
>   
>   /*
> @@ -311,8 +308,7 @@ ENTRY(int80_direct_trap)
>   UNLIKELY_START(ne, msi_check)
>           movl  $0x80,%edi
>           call  check_for_unexpected_msi
> -        RESTORE_ALL
> -        SAVE_ALL
> +        LOAD_C_CLOBBERED
>   UNLIKELY_END(msi_check)
>   
>           GET_CURRENT(%rbx)
> --- a/xen/include/asm-x86/x86_64/asm_defns.h
> +++ b/xen/include/asm-x86/x86_64/asm_defns.h
> @@ -5,11 +5,11 @@
>   
>   #ifdef CONFIG_FRAME_POINTER
>   /* Indicate special exception stack frame by inverting the frame pointer. */
> -#define SETUP_EXCEPTION_FRAME_POINTER           \
> -        movq  %rsp,%rbp;                        \
> +#define SETUP_EXCEPTION_FRAME_POINTER(offs)     \
> +        leaq  offs(%rsp),%rbp;                  \
>           notq  %rbp
>   #else
> -#define SETUP_EXCEPTION_FRAME_POINTER
> +#define SETUP_EXCEPTION_FRAME_POINTER(off)
Is it too pedantic to say that "off" here should be "offs"?
Just for consistency...

--
Mats


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