Re: [PATCH for-8.1] target/mips: Avoid shift by negative number in page_table_walk_refill()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 17/7/23 18:29, Peter Maydell wrote:
> Coverity points out that in page_table_walk_refill() we can shift by
> a negative number, which is undefined behaviour (CID 1452918,
> 1452920, 1452922).  We already catch the negative directory_shift and
> leaf_shift as being a "bail out early" case, but not until we've
> already used them to calculated some offset values.
> 
> Move the calculation of the offset values to after we've done the
> "return early if directory_shift or leaf_shift are -1" check.
> 
> Since walk_directory() re-calculates these shift values, add an
> assert() to tell Coverity that the caller has already ensured they
> won't be negative.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   target/mips/tcg/sysemu/tlb_helper.c | 20 +++++++++++++-------
>   1 file changed, 13 insertions(+), 7 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>