Re: [Xen-devel] [PATCH 30/34] xen: Add missing includes on different files

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-04-01 at 18:58 +0100, Julien Grall wrote:
> On 03/28/2014 09:59 AM, Ian Campbell wrote:
> > On Thu, 2014-03-27 at 17:47 +0000, Julien Grall wrote:
> >> On 03/27/2014 05:39 PM, Ian Campbell wrote:
> >>> On Thu, 2014-03-27 at 17:30 +0000, Julien Grall wrote:
> >>>> On 03/27/2014 05:11 PM, Ian Campbell wrote:
> >>>>> On Tue, 2014-03-25 at 16:55 +0000, Julien Grall wrote:
> >>>>>> This was spotted by -Wmissing-prototypes, which we can't enable 
> >>>>>> because there
> >>>>>> is exported function for assembly. I'm not sure if we need to add a 
> >>>>>> prototype
> >>>>>> for them.
> >>>>>
> >>>>> What exactly is the issue here?
> >>>>
> >>>> There a bunch of functions (see below for ARM) where the prototype is
> >>>> not defined before. Mainly because theses functions are used by the
> >>>> assembly code so we don't need to give a prototype.
> >>>>
> >>>> do_trap_*
> >>>> start_xen
> >>>> start_secondary
> >>>> leave_hypervisor_tail
> >>>
> >>> Is that all of them? Although their prototypes are useless there are few
> >>> enough of them that the benefit of being able to turn on
> >>> Wmissing-prototypes might make it worth it.
> >>
> >> From the common code there is 7 others:
> >>
> >> core_parking_helper and get_cur_idle_nums (both of them are used on C
> >> code but never defined in an header. I was lazy and I didn't write a 
> >> patch).
> >>
> >> __qdivrem
> >> __divdi3
> >> __umoddi3
> >> __moddi3
> >> __ldivmod_helper
> > 
> > Still not awful I guess.
> > 
> > Several of these are essentially library functions provided for the
> > compiler to emit calls to, I wonder if there is some compiler header
> > which we should be including which would prototype them. Probably not,
> > worth a look though.
> 
> These functions are not used by x86 (because of the if BITS_PER_LONG ==
> 32), and on ARM we provide eabi_* helpers.

Not sure I follow, what are you concluding there?

> > The compiler could see a call from C code to a function whose prototype
> > was marked with "called_from_asm_only".
> 
> I'm afraid there is no __attribute__ feature for a such thing. One
> solution could be introduce mismatch section as Linux (e.g: functions
> called from assembly are in a specific section).




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