Re: [Xen-devel] [PATCH 1/3] x86/irq: local_irq_restore() should not blindly popf

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.10.13 at 15:41, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> --- a/xen/include/asm-x86/system.h
> +++ b/xen/include/asm-x86/system.h
> @@ -159,8 +159,10 @@ static always_inline unsigned long __cmpxchg(
>  #define local_irq_restore(x)                                     \
>  ({                                                               \
>      BUILD_BUG_ON(sizeof(x) != sizeof(long));                     \
> -    asm volatile ( "push" __OS " %0 ; popf" __OS                 \
> -                   : : "g" (x) : "memory", "cc" );               \
> +    if ( x & X86_EFLAGS_IF )                                     \
> +        local_irq_enable();                                      \
> +    else                                                         \
> +        local_irq_disable();                                     \

_If_ you're going to re-do this using the mask-and-merge approach
I suggested in the other reply, may I ask that you also replace the
open coded (1<<9) a few lines down with X86_EFLAGS_IF (at once
making the comment there superfluous)?

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel