linux-kernel - Re: [PATCH 2/3] riscv: Fixup PAGE

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Date:   Tue, 25 May 2021 10:34:37 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Guo Ren <guoren@...nel.org>
Cc:     Christoph Hellwig <hch@...radead.org>,
        Anup Patel <anup.patel@....com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-sunxi@...ts.linux.dev, Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH 2/3] riscv: Fixup PAGE_UP in asm/page.h

On Tue, May 25, 2021 at 05:28:21PM +0800, Guo Ren wrote:
> On Tue, May 25, 2021 at 2:34 PM Christoph Hellwig <hch@...radead.org> wrote:
> >
> > On Mon, May 24, 2021 at 06:51:07AM +0000, guoren@...nel.org wrote:
> > > From: Guo Ren <guoren@...ux.alibaba.com>
> > >
> > > Current PAGE_UP implementation is wrong. PAGE_UP(0) should be
> > > 0x1000, but current implementation will give out 0.
> > >
> > > Although the current PAGE_UP isn't used, it will soon be used in
> > > tlb_flush optimization.
> >
> > Nak.  Please just remove the PAGE_UP/PAGE_DOWN macros just like they
> > have been removed from other architectures long ago and use the
> > generic DIV_ROUND_UP macro for your new code like everyone else.
> 
> This patch has been dropped because it's wrong, ref Anup's reply.
> 
> Remove PAGE_UP/DOWN is okay for me. How about:
>  static inline void local_flush_tlb_range_asid(unsigned long start,
> unsigned long size,
>                                               unsigned long asid)
>  {
> -       unsigned long page_add = PAGE_DOWN(start);
> -       unsigned long page_end = PAGE_UP(start + size);
> +       unsigned long page_add = _ALIGN_DOWN(start, PAGE_SIZE);
> +       unsigned long page_end = _ALIGN_UP(start + size, PAGE_SIZE);
> 
> _ALIGN_XXX are also defined in arch/riscv/include/asm/page.h.

And these also are leftovers from days gone by and should be removed.

I think this should simply be:

	
	unsigned long page_add = start & PAGE_MASK;
	unsigned long page_end = PAGE_ALIGN(start + size);

(and page_add is a pretty horrible name as well..)