Re: [PATCH v7] add param that allows bootline control of hardened usercopy

[Vlastimil Babka]

On 07/03/2018 09:43 PM, Chris von Recklinghausen wrote:

Subject: [PATCH v7] add param that allows bootline control of hardened
usercopy

s/bootline/boot time/ ?

> v1->v2:
>       remove CONFIG_HUC_DEFAULT_OFF
>       default is now enabled, boot param disables
>       move check to __check_object_size so as to not break optimization of
>               __builtin_constant_p()

Sorry for late and drive-by suggestion, but I think the change above is
kind of a waste because there's a function call overhead only to return
immediately.

Something like this should work and keep benefits of both the built-in
check and avoiding function call?

static __always_inline void check_object_size(const void *ptr, unsigned
long n, bool to_user)
{
        if (!__builtin_constant_p(n) &&
                        static_branch_likely(&bypass_usercopy_checks))
                __check_object_size(ptr, n, to_user);
}