Re: [PATCH v2] xen/dt-overlay: support phandle-based targeting in overlay_get_nodes_info

["Orzel, Michal" <michal.orzel@xxxxxxx>]

On 28-Apr-26 10:20, Nicola Vetrini wrote:
> On 2026-04-28 10:02, Michal Orzel wrote:
>> overlay_get_nodes_info() is called before fdt_overlay_apply() to 
>> extract
>> target paths from the overlay. This fails for overlays using 
>> phandle-based
>> targeting (target = <&label>) because DTC compiles these as unresolved
>> fixups (target = <0xffffffff>), causing fdt_overlay_target_offset() to
>> return -FDT_ERR_BADPHANDLE. Prior to this change users were forced to
>> manually modify the dtbo (even for hwdom) to switch from target to
>> target-phandle by manually inspecting also the host DTB.
>>
>> Introduce overlay_get_target_path() which directly handles the two
>> targeting cases that occur before fixup resolution:
>>  - target-path: the string property is returned directly.
>>  - target = <&label>: the label is found in the overlay's __fixups__
>>    node, then resolved to a path via the base DTB's __symbols__ node.
>>
>> Libfdt fdt_for_each_property_offset() violates MISRA R20.7. Despite
>> libfdt being excluded from the analysis, this causes ECLAIR scan to
>> report a regression because the violation introduced by a macro is
>> reported at the call site. Deviate R20.7 for libfdt.h.
>>
>> Reviewed-by: Luca Fancellu <luca.fancellu@xxxxxxx>
>> Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
>> ---
>> In my pre-push testing I realized ECLAIR allcode reported a violation 
>> related to
>> the use of fdt_for_each_property_offset. Libfdt is excluded from 
>> analysis but
>> this does not apply to e.g. macros used in other places.
>>
>> Changes in v2:
>>  - strip out from series that is ready to be committed
>>  - deviate 20.7 for libfdt.h. Discussed with Nicole.
>>
>> https://gitlab.com/xen-project/people/morzel/xen/-/pipelines/2484326830
>> ---
>>  .../eclair_analysis/ECLAIR/deviations.ecl     |  1 +
>>  xen/common/device-tree/dt-overlay.c           | 65 +++++++++++++++++--
>>  2 files changed, 60 insertions(+), 6 deletions(-)
>>
>> diff --git a/automation/eclair_analysis/ECLAIR/deviations.ecl 
>> b/automation/eclair_analysis/ECLAIR/deviations.ecl
>> index 30c323906924..5f0b73062474 100644
>> --- a/automation/eclair_analysis/ECLAIR/deviations.ecl
>> +++ b/automation/eclair_analysis/ECLAIR/deviations.ecl
>> @@ -631,6 +631,7 @@ not in scope for compliance are allowed, as that is 
>> imported code."
>>  -file_tag+={acpi_cpu_idle, "^xen/arch/x86/acpi/cpu_idle\\.c$"}
>>  -config=MC3A2.R20.7,reports+={safe, 
>> "any_area(any_loc(file(gnu_efi_include)||any_exp(macro(^NextMemoryDescriptor$))))"}
>>  -config=MC3A2.R20.7,reports+={safe, 
>> "any_area(any_loc(file(acpi_cpu_idle)))"}
>> +-config=MC3A2.R20.7,reports+={safe, 
>> "any_area(any_loc(any_exp(file(^xen/include/xen/libfdt/libfdt.h$))))"}
>>  -doc_end
>>
> 
> Nit: I think using a file_tag as above is better, but in any case use 
> libfdt\\.h in the regex
Ok. Provided I will do this on commit, may I convert this as your Rb/Ab?

~Michal