From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeremy Fitzhardinge Subject: Re: [PATCH] x86: Use __always_inline to ensure scale_delta linked to vsyscall section. Date: Fri, 13 Nov 2009 23:10:08 -0800 Message-ID: <4AFE57D0.8080100@goop.org> References: <706158FABBBA044BAD4FE898A02E4BC201CD31FD1D@pdsmsx503.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <706158FABBBA044BAD4FE898A02E4BC201CD31FD1D@pdsmsx503.ccr.corp.intel.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: "Zhang, Xiantao" Cc: Xen-devel List-Id: xen-devel@lists.xenproject.org On 11/13/09 20:53, Zhang, Xiantao wrote: > Hi, Jeremy > The attached patch should fix the bug: http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1529 which blocked us for weeks. Since scale_delta is used in the vsyscall vtime, so it should be inlined and linked to vsycall section, otherwise, dom0 should refuse the call. But due to GCC's optimization, scale_delta is compiled to a global function instead of inline function even if it is declared with inline attribute, so the issue occurs. To ensure this function is inlined to vsyscall section, a stricter attribute __always_inline should be used in its declaration. Thanks! > Thanks for tracking that down. J > Xiantao > > > From 3290d6e40f6c69ce3edd728f57780f088b7155e3 Mon Sep 17 00:00:00 2001 > From: Xiantao Zhang > Date: Fri, 13 Nov 2009 20:33:10 -0500 > Subject: [PATCH] x86: Use __always_inline to ensure scale_delta linked to vsyscall section. > > scale_delta is called in vsyscall vtime, so it should be linked to vsyscall > section and use fixmap to access it, otherwise unexpected page fault may raise > in vsyscall context, and leads to system dom0 panic. > > Signed-off-by: Xiantao Zhang > --- > arch/x86/kernel/pvclock.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c > index f47f91e..1b5d3e8 100644 > --- a/arch/x86/kernel/pvclock.c > +++ b/arch/x86/kernel/pvclock.c > @@ -28,7 +28,8 @@ > * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, > * yielding a 64-bit result. > */ > -static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift) > +static __always_inline > +u64 scale_delta(u64 delta, u32 mul_frac, int shift) > { > u64 product; > #ifdef __i386__ >