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SubjectRe: [RFC PATCH 16/33] Add support for Xen to entry.S.
* Rusty Russell (rusty@rustcorp.com.au) wrote:
> On Tue, 2006-07-18 at 00:00 -0700, Chris Wright wrote:
> > plain text document attachment (i386-entry.S)
> > - change cli/sti
> > - change test for user mode return to work for kernel mode in ring1
> > - check hypervisor saved event mask on return from exception
> > - add entry points for the hypervisor upcall handlers
> > - avoid math emulation check when running on Xen
> > - add nmi handler for running on Xen
> >
> > Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
> > Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
> > Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
> > Signed-off-by: Chris Wright <chrisw@sous-sol.org>
> >
> > ---
> > arch/i386/kernel/asm-offsets.c | 26 +++++++
> > arch/i386/kernel/entry.S | 141 ++++++++++++++++++++++++++++++++++++-----
> > arch/i386/mach-xen/setup-xen.c | 19 +++++
> > drivers/xen/core/features.c | 2
> > 4 files changed, 169 insertions(+), 19 deletions(-)
> >
> > diff -r 5cca1805b8a7 arch/i386/kernel/entry.S
> > --- a/arch/i386/kernel/entry.S Tue Jul 18 02:20:39 2006 -0400
> > +++ b/arch/i386/kernel/entry.S Tue Jul 18 02:22:56 2006 -0400
> > @@ -76,8 +76,39 @@ NT_MASK = 0x00004000
> > NT_MASK = 0x00004000
> > VM_MASK = 0x00020000
> >
> > +#ifndef CONFIG_XEN
> > +#define DISABLE_INTERRUPTS cli
> > +#define ENABLE_INTERRUPTS sti
> > +#else
> > +#include <xen/interface/xen.h>
> > +
> > +EVENT_MASK = 0x2E
> > +
> > +/* Offsets into shared_info_t. */
> > +#define evtchn_upcall_pending /* 0 */
> > +#define evtchn_upcall_mask 1
>
> Erk... Can we get these into asm-offsets?

Hmm, we put the vcpu shift in, guess we missed that. Thanks for noticing.

> > +
> > +#ifdef CONFIG_SMP
> > +/* Set %esi to point to the appropriate vcpu structure */
> > +#define GET_VCPU_INFO movl TI_cpu(%ebp),%esi ; \
> > + shl $SIZEOF_VCPU_INFO_SHIFT,%esi ; \
> > + addl HYPERVISOR_shared_info,%esi
> > +#else
> > +#define GET_VCPU_INFO movl HYPERVISOR_shared_info,%esi
> > +#endif
> > +
> > +/* The following end up using/clobbering %esi, because of GET_VCPU_INFO */
> > +#define __DISABLE_INTERRUPTS movb $1,evtchn_upcall_mask(%esi)
> > +#define DISABLE_INTERRUPTS GET_VCPU_INFO ; \
> > + __DISABLE_INTERRUPTS
> > +#define ENABLE_INTERRUPTS GET_VCPU_INFO ; \
> > + movb $0,evtchn_upcall_mask(%esi)
> > +#define __TEST_PENDING testb $0xFF,evtchn_upcall_pending(%esi)
> > +#endif
>
> Actually, is it possible to move these to a header somewhere? In the
> paravirt_ops patches I used the names CLI and STI (copied from the VMI
> patches), but didn't allow them to clobber any regs. They're defined in
> asm-i386/paravirt.h.

Sure, although it's only used here. Got a preference?

> If we want to allow them to clobber %esi, then your names are probably
> better, but we should clobber %esi in the !CONFIG_XEN case too if
> CONFIG_DEBUG_KERNEL.

That makes sense to me, just to catch those bugs.

thanks,
-chris
-
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