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Re: [XEN PATCH 5/7] xen/arm: traps: add ASSERT_UNREACHABLE() where needed



Hi Nicola,

On 11/12/2023 14:54, Nicola Vetrini wrote:
On 2023-12-11 13:32, Julien Grall wrote:
Hi,

On 11/12/2023 10:30, Nicola Vetrini wrote:
The branches of the switch after a call to 'do_unexpected_trap'
cannot return, but there is one path that may return, hence
only some clauses are marked with ASSERT_UNREACHABLE().
I don't understand why this is necessary. The code should never be reachable because do_unexpected_trap() is a noreturn().

Cheers,

It was meant as a safeguard against mistakes.

I am confused about which mistakes you are trying to prevent. Are you saying you are not trusting the noreturn attribute?

And if so, are you intending to add ASSERT_UNREACHABLE() after every single call to noreturn functions?

There are MISRA rules that deal with this aspect (e.g., a noreturn function should not return), but they are not in Amendment 2, which is what Xen is following.
Do you mind providing a bit more details about the rules you are talking about? At least the numbers would be helpful.

Cheers,

--
Julien Grall



 


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