Re: [RFC PATCH] xen/build: Add cppcheck and cppcheck-html make rules

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Julien,

> On 24 Mar 2022, at 13:00, Julien Grall <julien@xxxxxxx> wrote:
> 
> Hi Bertrand,
> 
> On 24/03/2022 11:04, Bertrand Marquis wrote:
>> cppcheck can be used to check Xen code quality.
> 
> Is there anything we should be concerned of in the initial report?

Nothing major no.
Michal will soon push a serie with a first set of fixes, mostly related to 
unused variables.

> 
>> To create a report do "make cppcheck" on a built tree adding any options
>> you added during the process you used to build xen (like CROSS_COMPILE
>> or XEN_TARGET_ARCH). This will generate an xml report xen-cppcheck.xml.
>> To create a html report do "make cppcheck-html" in the same way and a
>> full report to be seen in a browser will be generated in
>> cppcheck-htmlreport/index.html.
>> For better results it is recommended to build your own cppcheck from the
>> latest sources that you can find at [1].
>> Development and result analysis has been done with cppcheck 2.7.
> 
> We want to write down the minimum version of cppcheck we are going to 
> support. My suggestion would be to use the version you picked for your 
> development.

Agree, 2.7 (current stable) should be the one as we had some unstable 
behaviours with other versions.
Should I put that in the main readme ?

> 
>> The Makefile rule is searching for all C files which have been compiled
>> (ie which have a generated .o file) and is running cppcheck on all of
>> them using the current configuration of xen so only the code actually
>> compiled is checked.
>> A new tool is introduced to merge all cppcheck reports into one global
>> report including all findings and removing duplicates.
>> Some extra variables can be used to customize the report:
>> - CPPCHECK can be used to give the full path to the cppcheck binary to
>> use (default is to use the one from the standard path).
>> - CPPCHECK_HTMLREPORT can be used to give the full path to
>> cppcheck-htmlreport (default is to use the one from the standard path).
>> This has been tested on several arm configurations (x86 should work but
>> has not been tested).
>> [1] https://cppcheck.sourceforge.io/
>> Signed-off-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
>> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
>> ---
>>  .gitignore                           |  3 ++
>>  xen/Makefile                         | 75 +++++++++++++++++++++++++++-
>>  xen/arch/arm/include/asm/processor.h |  4 +-
>>  xen/include/xen/config.h             |  4 ++
>>  xen/include/xen/kconfig.h            |  5 ++
>>  xen/tools/merge_cppcheck_reports.py  | 73 +++++++++++++++++++++++++++
> 
> In the long term, I think it would be useful if we generate the report 
> regularly. We might be able to hook the script that generate 
> https://xenbits.xen.org/docs/.

Agree

> 
>> diff --git a/xen/arch/arm/include/asm/processor.h 
>> b/xen/arch/arm/include/asm/processor.h
>> index 852b5f3c24..0b4ba73760 100644
>> --- a/xen/arch/arm/include/asm/processor.h
>> +++ b/xen/arch/arm/include/asm/processor.h
>> @@ -219,9 +219,11 @@
>>                           SCTLR_Axx_ELx_A    | SCTLR_Axx_ELx_C   |\
>>                           SCTLR_Axx_ELx_WXN  | SCTLR_Axx_ELx_EE)
>>  -#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffUL
>> +#ifndef CPPCHECK
>> +#if (SCTLR_EL2_SET ^ SCTLR_EL2_CLEAR) != 0xffffffffffffffffULL
>>  #error "Inconsistent SCTLR_EL2 set/clear bits"
>>  #endif
>> +#endif
> 
> Why is it necessary?

The ULL was an attempt to fix but did not work. I will remove that in the next 
version.
Here cppcheck preprocessor is wrongly generating the error for a reason that I 
could not understand, hence the ifdef.

Cheers
Bertrand

> 
> Cheers,
> 
> -- 
> Julien Grall