Improve Space Software Quality with POLYSPACE Aurore Dupuis

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SPACE SOFTWARE1

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CNES – National Space Agency

Involved in systems characterized by :

• Space Constraints

• Innovation

• Technological Risk

Software is present everywhere in these systems.

Improve Space Software Quality with Polyspace

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Space Software

2 major space software types :

• Embedded software

• Ground software

2 major software issues :

• Reliability

• Maintainability

Improve Space Software Quality with Polyspace

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Software Assurance Quality

Based on ECSS/CNES referential

• ECSS-Q-ST-80 - Software product assurance

• Language specific coding standards

• Code analysis tools such as Polyspace

• Software quality team

Improve Space Software Quality with Polyspace

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ANALYSIS CONTEXT 2

Software Quality Team Mission

Much more than code analysis

• Support to Quality Engineer

• Normalisation

• Analysis Tools Watch

• Code Analysis

• …

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Software Development Context

• Very few internal development

• Suppliers analyze the code they produce

Software Quality Team

Checks supplier code

(only the most critical ones)

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Software Quality Team Organization

Software Quality Team

ECSS – Q80 Analysis Tools(Polyspace, …)

CommunityContact

CNES project team

Quality Engineer

Software supplier

Improve Space Software Quality with Polyspace

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POLYSPACE ANALYSIS3

Polyspace version and configuration

Polyspace version used is 2012a

Polyspace metrics is not used for security reason (no authentication service, code duplication)

later versions of Polyspace do support password protection of Polyspace metrics

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MISRA/JSF Rules

CNES coding rules match partially MISRA-C rules.

CNES only uses this function on recurrent embedded software in order to verify that the number of defects is not increasing.

JSF++ Rules are not checked with Polyspace yet. The comparison with CNES coding rules is still in progress.

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Bugs research

CNES principal use of Polyspace is dedicated to the bugs finding on embedded software and critical ground software.

Most of analyzed code is C code, the rest is C++ (which represents a large volume in terms of files).

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Bugs finding – Analyses 2010-2012

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Analyses

C

C++

1113858

327498

SLOC (source lines of code)

C

C++

Analysis process – Launch Context

Improve Space Software Quality with Polyspace

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Software Quality Team

CNES project team

Software supplier

Delivery

Ask for analysis if needed

Analyse

Analysis process – Launch Polyspace

• Unit by unit analysis may be launched first if the development is not mature enough

• Global analysis

determining entry points

defining compiler options (little/big endian, …)

with the project team

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Analysis process – Analyze results

• Red points

Red points are almost always real bugs (except for task definition),

Such bugs are

communicated to the project team to be fixed ASAP (as soon as possible),

fixed locally to launch the analysis,

Each code modification is traced and included into the analysis report,

Improve Space Software Quality with Polyspace

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Analysis process – Analyze results

• Grey points

Almost all grey points is linked to robustness,

Grey points not related to robustness are bounced to the project team,

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Analysis process – Analyze results

• Orange points

NIV and IDP are linked to memory access, these points are not verified by the software quality team.

o The hypothesis done is that the project team masters memory accesses. These points are almost never communicated to the project.

Other orange points are analyzed, only proved bugs and potential bugs are synthetized into the report and presented to the project team

o Software quality team has to argument and explain the need to correct these points, giving priority

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Analysis process – Analyze results

• Shared variables

Shared variables are identified byPolyspace and listed into the report

The project team has to check their use without concurrent access

o In some cases, this work is done by the software quality team if critical sections are well identified

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Analysis report

CNES has its own report template.

Result reports are generated using Polyspace. The generated tables are inserted into the CNES report.

Improve Space Software Quality with Polyspace

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Metrics

• About 30 analyses with Polyspace between 2010 and 2012 and 6 analysis in 2013

• About 10 analysis led to bugs discovery

• Current bugs

Overflow

Cast

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CONCLUSION4

Conclusion

Embedded space software is critical, a bug can compromise a whole space mission.

CNES needs tools to analyze code in order to find residual bugs.

Polyspace has been successfully useful to find overflows and cast problems.

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Thanks for your attention

ContactAurore DUPUIS – aurore.dupuis@cnes.fr

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Improve Space Software Quality with Polyspace

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