linux-kernel - Re: [PATCH v3 13/34] m68k: Implement the new page table range API

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Date:   Sun, 5 Mar 2023 11:16:13 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     linux-mm@...ck.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-m68k@...ts.linux-m68k.org
Subject: Re: [PATCH v3 13/34] m68k: Implement the new page table range API

Hi Willy,

On Tue, Feb 28, 2023 at 10:37 PM Matthew Wilcox (Oracle)
<willy@...radead.org> wrote:
> Add set_ptes(), update_mmu_cache_range(), flush_icache_pages() and
> flush_dcache_folio().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

Thanks for your patch!

> --- a/arch/m68k/include/asm/cacheflush_mm.h
> +++ b/arch/m68k/include/asm/cacheflush_mm.h
> @@ -220,24 +220,28 @@ static inline void flush_cache_page(struct vm_area_struct *vma, unsigned long vm
>
>  /* Push the page at kernel virtual address and clear the icache */
>  /* RZ: use cpush %bc instead of cpush %dc, cinv %ic */
> -static inline void __flush_page_to_ram(void *vaddr)
> +static inline void __flush_pages_to_ram(void *vaddr, unsigned int nr)
>  {
>         if (CPU_IS_COLDFIRE) {
>                 unsigned long addr, start, end;
>                 addr = ((unsigned long) vaddr) & ~(PAGE_SIZE - 1);
>                 start = addr & ICACHE_SET_MASK;
> -               end = (addr + PAGE_SIZE - 1) & ICACHE_SET_MASK;
> +               end = (addr + nr * PAGE_SIZE - 1) & ICACHE_SET_MASK;
>                 if (start > end) {
>                         flush_cf_bcache(0, end);
>                         end = ICACHE_MAX_ADDR;
>                 }
>                 flush_cf_bcache(start, end);
>         } else if (CPU_IS_040_OR_060) {
> -               __asm__ __volatile__("nop\n\t"
> -                                    ".chip 68040\n\t"
> -                                    "cpushp %%bc,(%0)\n\t"
> -                                    ".chip 68k"
> -                                    : : "a" (__pa(vaddr)));
> +               unsigned long paddr = __pa(vaddr);
> +
> +               while (nr--) {
> +                       __asm__ __volatile__("nop\n\t"
> +                                            ".chip 68040\n\t"
> +                                            "cpushp %%bc,(%0)\n\t"
> +                                            ".chip 68k"
> +                                            : : "a" (paddr + nr * PAGE_SIZE));

As gcc (9.5.0) keeps on calculating "paddr + nr * PAGE_SIZE"
inside the loop (albeit using a shift instead of a multiplication),
please use "paddr" here, followed by "paddr += PAGE_SIZE;".

Gr{oetje,eeting}s,

                        Geert


--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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