Re: [XEN PATCH][for-next][for-4.19 v2 1/8] xen/include: add macro LOWEST_BIT

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 16 Oct 2023, Jan Beulich wrote:
> On 16.10.2023 18:17, Nicola Vetrini wrote:
> > On 16/10/2023 17:33, Jan Beulich wrote:
> >> On 12.10.2023 17:28, Nicola Vetrini wrote:
> >>> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
> >>> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
> >>> @@ -274,6 +274,12 @@ still non-negative."
> >>>  -config=MC3R1.R10.1,etypes+={safe, 
> >>> "stmt(operator(logical)||node(conditional_operator||binary_conditional_operator))",
> >>>  
> >>> "dst_type(ebool||boolean)"}
> >>>  -doc_end
> >>>
> >>> +-doc_begin="The macro LOWEST_BIT encapsulates a well-known pattern to 
> >>> obtain the value
> >>> +2^ffs(x) for unsigned integers on two's complement architectures
> >>> +(all the architectures supported by Xen satisfy this requirement)."
> >>> +-config=MC3R1.R10.1,reports+={safe, 
> >>> "any_area(any_loc(any_exp(macro(^LOWEST_BIT$))))"}
> >>> +-doc_end
> >>
> >> Why is this added here rather than by ...
> >>
> >>> --- a/xen/include/xen/macros.h
> >>> +++ b/xen/include/xen/macros.h
> >>> @@ -8,8 +8,10 @@
> >>>  #define DIV_ROUND(n, d) (((n) + (d) / 2) / (d))
> >>>  #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
> >>>
> >>> -#define MASK_EXTR(v, m) (((v) & (m)) / ((m) & -(m)))
> >>> -#define MASK_INSR(v, m) (((v) * ((m) & -(m))) & (m))
> >>
> >> a SAF-<n>-safe comment here?
> >>
> > 
> > One reason is that now that violations only belonging to tool 
> > configurations
> > and similar are documented in docs/misra/deviations.rst (committed in 
> > Stefano's
> > branch for-4.19 [1]).
> 
> But tool configuration means every analysis tool needs configuring
> separately. That's why the comment tagging scheme was decided to be
> preferred, iirc.
> 
> > Also, there were disagreements on the SAF naming 
> > scheme, and
> > patches like those would not be accepted at the moment.
> 
> Well, that needs resolving. The naming there shouldn't lead to patches
> being accepted that later may need redoing.

I agree