linux-kernel - Re: [PATCH 10/16] sparc64: use the generic get_user_pages

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Message-ID: <20190603074455.GC22920@lst.de>
Date:   Mon, 3 Jun 2019 09:44:55 +0200
From:   Christoph Hellwig <hch@....de>
To:     Hillf Danton <hdanton@...a.com>
Cc:     Christoph Hellwig <hch@....de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        "David S. Miller" <davem@...emloft.net>,
        Nicholas Piggin <npiggin@...il.com>,
        Khalid Aziz <khalid.aziz@...cle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linux-mips@...r.kernel.org, linux-sh@...r.kernel.org,
        sparclinux@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org, x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/16] sparc64: use the generic get_user_pages_fast code

On Sun, Jun 02, 2019 at 03:39:48PM +0800, Hillf Danton wrote:
> 
> Hi Christoph 
> 
> On Sat,  1 Jun 2019 09:49:53 +0200 Christoph Hellwig wrote:
> > 
> > diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
> > index a93eca29e85a..2301ab5250e4 100644
> > --- a/arch/sparc/include/asm/pgtable_64.h
> > +++ b/arch/sparc/include/asm/pgtable_64.h
> > @@ -1098,6 +1098,24 @@ static inline unsigned long untagged_addr(unsigned long start)
> >  }
> >  #define untagged_addr untagged_addr
> >  
> > +static inline bool pte_access_permitted(pte_t pte, bool write)
> > +{
> > +	u64 prot;
> > +
> > +	if (tlb_type == hypervisor) {
> > +		prot = _PAGE_PRESENT_4V | _PAGE_P_4V;
> > +		if (prot)
> 
> Feel free to correct me if I misread or miss anything.
> It looks like a typo: s/prot/write/, as checking _PAGE_PRESENT_4V and
> _PAGE_P_4V makes prot always have _PAGE_WRITE_4V set, regardless of write.

True, the if prot should be if write.