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Re: [XEN PATCH][for-4.19] domain: add ASSERT to help static analysis tools



Hi everyone,

I trimmed the thread a bit, to make this more readable.

IMHO, the only viable option would be to have a configuration to keep
ASSERT in production build for scanning tools.

But wouldn't that then likely mean scanning to be done on builds not also used in production? Would doing so even be permitted when certification is a requirement? Or do you expect such production builds to be used with the assertions left in place (increasing the risk of a crash; recall that assertions themselves may also be wrong, and hence one triggering in rare
cases may not really be a reason to bring down the system)?

I will leave Stefano/Nicola to answer from the certification perspective. But I don't really see how we could get away unless we replace most of the ASSERT() with proper runtime check (which may not be desirable for ASSERT()s
like this one).

For sure we don't want to replace ASSERTs with runtime checks.

Nicola, do we really need the ASSERT to be implemented as a check, or
would the presence of the ASSERT alone suffice as a tag, the same way we
would be using /* SAF-xx-safe */ or asmlinkage?

If we only need ASSERT as a deviation tag, then production builds vs.
debug build doesn't matter.

If ECLAIR actually needs ASSERT to be implemented as a check, could we
have a special #define to define ASSERT in a special way for static
analysis tools in production builds? For instance:

#ifdef STATIC_ANALYSIS
#define ASSERT(p) \
do { if ( unlikely(!(p)) ) printk("ASSERT triggered %s:%d", __file__,__LINE__); } while (0)
#endif

Just to make 100% clear, you are saying that assessor will be happy if we analyze it with ASSERT enabled but in production we use it wout them enabled? The assumption here is that they should have *never* been triggered so they surely should not happen in production.

Cheers,

First of all, Andrew is experimenting with an alternate solution, so we should wait making
any decision here until he can share the outcome of his findings.
However, from a certification perspective, the fact that the codebase is tested with asserts enabled is a strong enough claim for a justification to be based on an assertion;
the code path just needs to be exercised by the tests.
Getting into the business of how to define asserts for static analysis is likely to
just cause more trouble.

--
Nicola Vetrini, BSc
Software Engineer, BUGSENG srl (https://bugseng.com)



 


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