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[108.223.40.66]) by smtp.gmail.com with ESMTPSA id k26-v6sm5740287pfb.167.2018.09.25.20.21.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Sep 2018 20:21:02 -0700 (PDT) Date: Tue, 25 Sep 2018 20:21:01 -0700 From: Guenter Roeck To: John David Anglin Cc: jejb@parisc-linux.org, Helge Deller , linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] parisc: Remove PTE load and fault check from L2_ptep macro Message-ID: <20180926032101.GA2458@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Sun, Sep 23, 2018 at 10:55:18AM -0400, John David Anglin wrote: > This change removes the PTE load and present check from the L2_ptep > macro. The load and check for kernel pages is now done in the tlb_lock > macro. This avoids a double load and check for user pages. The load > and check for user pages is now done inside the lock so the fault > handler can't be called while the entry is being updated. > This patch causes my parisc qemu tests to fail. Unfortunately I don't have any useful log output; the failure is silent. Reverting the patch fixes the problem. Guenter > Signed-off-by: John David Anglin > Signed-off-by: Helge Deller > --- > arch/parisc/kernel/entry.S | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S > index eeee1d2c4b8e..3371472379a6 100644 > --- a/arch/parisc/kernel/entry.S > +++ b/arch/parisc/kernel/entry.S > @@ -431,8 +431,6 @@ > extru \va,31-PAGE_SHIFT,ASM_BITS_PER_PTE,\index > dep %r0,31,PAGE_SHIFT,\pmd /* clear offset */ > shladd \index,BITS_PER_PTE_ENTRY,\pmd,\pmd /* pmd is now pte */ > - LDREG %r0(\pmd),\pte > - bb,>=,n \pte,_PAGE_PRESENT_BIT,\fault > .endm > > /* Look up PTE in a 3-Level scheme. > @@ -463,7 +461,7 @@ > L2_ptep \pgd,\pte,\index,\va,\fault > .endm > > - /* Acquire pa_tlb_lock lock and recheck page is still present. */ > + /* Acquire pa_tlb_lock lock and check page is present. */ > .macro tlb_lock spc,ptp,pte,tmp,tmp1,fault > #ifdef CONFIG_SMP > cmpib,COND(=),n 0,\spc,2f > @@ -472,10 +470,12 @@ > cmpib,COND(=) 0,\tmp1,1b > nop > LDREG 0(\ptp),\pte > - bb,<,n \pte,_PAGE_PRESENT_BIT,2f > + bb,<,n \pte,_PAGE_PRESENT_BIT,3f > b \fault > stw \spc,0(\tmp) > -2: > +2: LDREG 0(\ptp),\pte > + bb,>=,n \pte,_PAGE_PRESENT_BIT,\fault > +3: > #endif > .endm > > -- > 2.7.4