Re: [PATCH] virtual_region: address Misra C:2012 rule 18.3

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/10/2026 12:52 pm, Dmytro Prokopchuk1 wrote:
> find_text_region() tests whether an arbitrary address lies inside
> [text_start, text_end). The address and those bounds are not known to
> point into one object, so relational operators on the pointers are
> undefined behaviour and violate Misra C:2012 rule 18.3.
>
> The bounds are cast to unsigned long because addr already has that
> type. The type is wide enough to hold a pointer, so the comparison
> result stays the same.
>
> No functional changes.
>
> Signed-off-by: Dmytro Prokopchuk <dmytro_prokopchuk1@xxxxxxxx>
> ---
> A deviation does not fit because find_text_region() compares an arbitrary 
> address
> with bounds (as was proposed here:
> https://patchew.org/Xen/901917945f704643e95842a773be9e8676f76d10.1755690681.git.dmytro._5Fprokopchuk1@xxxxxxxx/).
>
> Casting resolve this MISRA violation.
> ---
>  xen/common/virtual_region.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/xen/common/virtual_region.c b/xen/common/virtual_region.c
> index 1dc2e9f592..a30e6b9c30 100644
> --- a/xen/common/virtual_region.c
> +++ b/xen/common/virtual_region.c
> @@ -83,8 +83,8 @@ const struct virtual_region *find_text_region(unsigned long 
> addr)
>      rcu_read_lock(&rcu_virtual_region_lock);
>      list_for_each_entry_rcu ( iter, &virtual_region_list, list )
>      {
> -        if ( (void *)addr >= iter->text_start &&
> -             (void *)addr <  iter->text_end )
> +        if ( addr >= (unsigned long)iter->text_start &&
> +             addr < (unsigned long)iter->text_end )


Please don't break the tabulation.   It's important for legibility.

~Andrew