From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: [PATCH] xen: arm: arm64: Fix memory cloberring issues during VFP save restore. Date: Fri, 7 Feb 2014 14:29:01 +0000 Message-ID: <52F4EDAD.7020500@eu.citrix.com> References: <1391769538-9091-1-git-send-email-pranavkumar@linaro.org> <1391773158.2162.81.camel@kazak.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1391773158.2162.81.camel@kazak.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , Pranavkumar Sawargaonkar Cc: patches@apm.com, patches@linaro.org, stefano.stabellini@citrix.com, Anup Patel , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 02/07/2014 11:39 AM, Ian Campbell wrote: > On Fri, 2014-02-07 at 16:08 +0530, Pranavkumar Sawargaonkar wrote: >> This patch addresses memory cloberring issue mentioed by Julien Grall >> with my earlier patch - >> Ref: >> http://www.gossamer-threads.com/lists/xen/devel/316247 >> >> Signed-off-by: Pranavkumar Sawargaonkar >> Signed-off-by: Anup Patel >> --- >> xen/arch/arm/arm64/vfp.c | 70 ++++++++++++++++++++++++---------------------- >> 1 file changed, 36 insertions(+), 34 deletions(-) >> >> diff --git a/xen/arch/arm/arm64/vfp.c b/xen/arch/arm/arm64/vfp.c >> index c09cf0c..62f56a3 100644 >> --- a/xen/arch/arm/arm64/vfp.c >> +++ b/xen/arch/arm/arm64/vfp.c >> @@ -8,23 +8,24 @@ void vfp_save_state(struct vcpu *v) >> if ( !cpu_has_fp ) >> return; >> >> - asm volatile("stp q0, q1, [%0, #16 * 0]\n\t" >> - "stp q2, q3, [%0, #16 * 2]\n\t" >> - "stp q4, q5, [%0, #16 * 4]\n\t" >> - "stp q6, q7, [%0, #16 * 6]\n\t" >> - "stp q8, q9, [%0, #16 * 8]\n\t" >> - "stp q10, q11, [%0, #16 * 10]\n\t" >> - "stp q12, q13, [%0, #16 * 12]\n\t" >> - "stp q14, q15, [%0, #16 * 14]\n\t" >> - "stp q16, q17, [%0, #16 * 16]\n\t" >> - "stp q18, q19, [%0, #16 * 18]\n\t" >> - "stp q20, q21, [%0, #16 * 20]\n\t" >> - "stp q22, q23, [%0, #16 * 22]\n\t" >> - "stp q24, q25, [%0, #16 * 24]\n\t" >> - "stp q26, q27, [%0, #16 * 26]\n\t" >> - "stp q28, q29, [%0, #16 * 28]\n\t" >> - "stp q30, q31, [%0, #16 * 30]\n\t" >> - :: "r" ((char *)(&v->arch.vfp.fpregs)): "memory"); >> + asm volatile("stp q0, q1, [%1, #16 * 0]\n\t" >> + "stp q2, q3, [%1, #16 * 2]\n\t" >> + "stp q4, q5, [%1, #16 * 4]\n\t" >> + "stp q6, q7, [%1, #16 * 6]\n\t" >> + "stp q8, q9, [%1, #16 * 8]\n\t" >> + "stp q10, q11, [%1, #16 * 10]\n\t" >> + "stp q12, q13, [%1, #16 * 12]\n\t" >> + "stp q14, q15, [%1, #16 * 14]\n\t" >> + "stp q16, q17, [%1, #16 * 16]\n\t" >> + "stp q18, q19, [%1, #16 * 18]\n\t" >> + "stp q20, q21, [%1, #16 * 20]\n\t" >> + "stp q22, q23, [%1, #16 * 22]\n\t" >> + "stp q24, q25, [%1, #16 * 24]\n\t" >> + "stp q26, q27, [%1, #16 * 26]\n\t" >> + "stp q28, q29, [%1, #16 * 28]\n\t" >> + "stp q30, q31, [%1, #16 * 30]\n\t" >> + :"=Q" (*v->arch.vfp.fpregs): "r" (v->arch.vfp.fpregs) >> + : "memory"); > The point of this change was to be able to drop the memory clobbers. > > George, I'd like to take this in 4.4 if possible -- I wanted to get the > baseline functionality fixed for 4.4 ASAP since it was quite a big hole > which is why I committed without waiting for this respin. > > The issue is that the patch which was committed yesterday clobbers all > of memory and not just the bits the inline asm touches. Obviously there's not much point in releasing a version with a fix that doesn't work. :-) Release-acked-by: George Dunlap