Re: [PATCH 1/5] m68knommu: fix overwriting of bits in ColdFire V3 cache control

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Greg,

On Mon, Jun 15, 2020 at 8:38 AM Greg Ungerer <gerg@linux-m68k.org> wrote:
> The Cache Control Register (CACR) of the ColdFire V3 has bits that
> control high level caching functions, and also enable/disable the use
> of the alternate stack pointer register (the EUSP bit) to provide
> separate supervisor and user stack pointer registers. The code as
> it is today will blindly clear the EUSP bit on cache actions like
> invalidation. So it is broken for this case - and that will result
> in failed booting (interrupt entry and exit processing will be
> completely hosed).
>
> This only affects ColdFire V3 parts that support the alternate stack
> register (like the 5329 for example) - generally speaking new parts do,
> older parts don't. It has no impact on ColdFire V3 parts with the single
> stack pointer, like the 5307 for example.
>
> Fix the cache bit defines used, so they maintain the EUSP bit when
> carrying out cache actions through the CACR register.
>
> Signed-off-by: Greg Ungerer <gerg@linux-m68k.org>

Thanks for your patch!

> --- a/arch/m68k/include/asm/m53xxacr.h
> +++ b/arch/m68k/include/asm/m53xxacr.h
> @@ -89,9 +89,9 @@
>   * coherency though in all cases. And for copyback caches we will need
>   * to push cached data as well.
>   */
> -#define CACHE_INIT       CACR_CINVA
> -#define CACHE_INVALIDATE  CACR_CINVA
> -#define CACHE_INVALIDATED CACR_CINVA
> +#define CACHE_INIT        (CACHE_MODE + CACR_CINVA)

This line is different from the RFC v2 in
https://www.spinics.net/lists/linux-m68k/msg13973.html ?

> +#define CACHE_INVALIDATE  (CACHE_MODE + CACR_CINVA)
> +#define CACHE_INVALIDATED (CACHE_MODE + CACR_CINVA)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds