Re: [Xen-devel] [PATCH v2 1/7] x86: Add support for STAC/CLAC instructions

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.04.14 at 10:51, <feng.wu@xxxxxxxxx> wrote:
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Perhaps worth avoiding the basic uses then, by converting them to
>> extended? Passing these % or %% to the macro looks rather ugly,
>> so if the suggestion isn't viable, some other trick can certainly be
>> found to avoid this.
> 
> Need to add CLAC in the beginning of interrupt in the following macro, which 
> uses
> the basic inline assembly, seems it is hard to convert this one to extended 
> format. I
> have been thinking about this for some time and tried several method, but I 
> am kind of
> run out of ideas about it. Jan, do you have any suggestion about this?
> 
> Thanks very much in advance!
> 
> #define BUILD_COMMON_IRQ()                      \
> __asm__(                                        \
>     "\n" __ALIGN_STR"\n"                        \
>     "common_interrupt:\n\t"                     \
>     STR(SAVE_ALL) "\n\t"                        \
>     "movq %rsp,%rdi\n\t"                        \
>     "callq " STR(do_IRQ) "\n\t"                 \
>     "jmp ret_from_intr\n");

I agree with Andrew - now that we don't have to care about
otherwise resulting code duplication (leaving aside that there wasn't
much of it here anyway, the bulk of it is from BUILD_IRQ()), this
should simply be moved into entry.S, at once making it better readable
(and a follow-up patch, unless you want to do it all in one go, would
be to also move the BUILD_IRQ() consumer into entry.S).

Jan


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