From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>,
Jun Nakajima <jun.nakajima@intel.com>,
andrew.cooper3@citrix.com, mpohlack@amazon.de,
ross.lagerwall@citrix.com, Julien Grall <julien.grall@arm.com>,
Stefano Stabellini <stefano.stabellini@citrix.com>,
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
sasha.levin@oracle.com, xen-devel@lists.xenproject.org,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v5 11/28] xsplice: Implement support for applying/reverting/replacing patches.
Date: Wed, 6 Apr 2016 23:05:23 -0400 [thread overview]
Message-ID: <20160407030523.GB24604@char.us.oracle.com> (raw)
In-Reply-To: <57022EBB02000078000E28F7@prv-mh.provo.novell.com>
> >> So you check for there being one such section. Is having multiple
> >> of them okay / meaningful?
> >
> > /me blinks. You can have multiple ELF sections with the same name?
> > I will double-check the spec over the weekend to see.
>
> Of course you can. Remember me telling you that using section
> names for identification is a bad idea (even if widely done that
> way)? That's precisely because section names in the spec serve
> no meaning other than making sections identifiable to the human
> eye. For certain sections there's a more or less strict convention
> on what their names should be, but that's all there is to names.
> Section types and attributes really are what describe their
> purposes.
This is going to take a bit of time to get right I am afraid.
(The checks are easy - but make sure the payload files that are generated
are doing the right thing).
>
> And even if that really was forbidden by the spec, you'd still need
> to make sure the binary meets the spec.
Yes.
> >> > +void check_for_xsplice_work(void)
> >> > +{
> >> > + /* Set at -1, so will go up to num_online_cpus - 1. */
> >> > + if ( atomic_inc_and_test(&xsplice_work.semaphore) )
> >> > + {
> >> > + struct payload *p;
> >> > + unsigned int total_cpus;
> >> > +
> >> > + p = xsplice_work.data;
> >> > + if ( !get_cpu_maps() )
> >> > + {
> >> > + printk(XENLOG_ERR "%s%s: CPU%u - unable to get cpu_maps lock!\n",
> >> > + XSPLICE, p->name, cpu);
> >> > + per_cpu(work_to_do, cpu) = 0;
> >> > + xsplice_work.data->rc = -EBUSY;
> >> > + xsplice_work.do_work = 0;
> >>
> >> On x86 such possibly simultaneous accesses may be okay, but is
> >> that universally the case? Wouldn't it better be only the monarch
> >> which updates shared data?
> >
> > Monarch? Oh you mean arch specific code path?
>
> Oh, I think you call it "master" elsewhere. IA64 terminology which
> I came to like.
>
The master CPU is the one updating it.
> >> > + /* All CPUs are waiting, now signal to disable IRQs. */
> >> > + xsplice_work.ready = 1;
> >> > + smp_wmb();
> >> > +
> >> > + atomic_inc(&xsplice_work.irq_semaphore);
> >> > + if ( !xsplice_do_wait(&xsplice_work.irq_semaphore, timeout, total_cpus,
> >> > + "Timed out on IRQ semaphore") )
> >>
> >> I'd prefer if the common parts of that message moved into
> >> xsplice_do_wait() - no reason to have more string literal space
> >> occupied than really needed. Also, looking back, the respective
> >> function parameter could do with a more descriptive name.
> >>
> >> And then - does it make sense to wait the perhaps full 30ms
> >> on this second step? Rendezvoused CPUs should react rather
> >> quickly to the signal to disable interrupts.
> >
> > We don't reset the timeout - the timeout is for both calls
> > to xsplice_do_wait.
>
> I understand that's the way it's right now, but that's what I'm putting
> under question. Rendezvousing CPUs is quite a bit more at risk of
> taking some time compared to having already rendezvoused CPUs
> disable their IRQs.
Yes. I could expand the timeout, but maybe have some reset (add more
timeout) once CPUs come along?
> >> > static int __init xsplice_init(void)
> >> > {
> >> > + BUILD_BUG_ON( sizeof(struct xsplice_patch_func) != 64 );
> >> > + BUILD_BUG_ON( offsetof(struct xsplice_patch_func, new_addr) != 8 );
> >> > + BUILD_BUG_ON( offsetof(struct xsplice_patch_func, new_size) != 24 );
> >>
> >> What assumptions get broken if these sizes change?
> >
> > I think you mean the offsets? They can change. I added them to make sure
> > that on 32-bit hypervisor (ARM) the offsets would be the same as on 64-bit
> > hypervisor (x86).
> >
> > The size however MUST remain the same - otherwise the toolstack won't
> > produce proper payloads anymore.
>
> Well, that's a very bad thing then imo. You'd better version the
> structure instead.
Andrew reminded me that we also will have build-ids. Those by nature imply
a version. That is the payload won't ever apply against a different type
hypervisor.
But I still added a version field in the struct so when we get the
'checking the old code' we have a mechanism to select -build-id or
the newer way.
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next prev parent reply other threads:[~2016-04-07 3:06 UTC|newest]
Thread overview: 190+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-24 20:00 [PATCH v5] xSplice v1 design and implementation Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane Konrad Rzeszutek Wilk
2016-03-24 20:22 ` Andrew Cooper
2016-03-24 21:07 ` Konrad Rzeszutek Wilk
2016-03-24 21:30 ` Konrad Rzeszutek Wilk
2016-03-30 15:43 ` Jan Beulich
2016-03-31 6:30 ` Jan Beulich
2016-03-31 11:43 ` Konrad Rzeszutek Wilk
2016-03-31 12:07 ` Jan Beulich
2016-03-31 13:28 ` REST MAINTAINERS feedback requested Was:Re: " Konrad Rzeszutek Wilk
2016-03-31 13:50 ` Jan Beulich
2016-04-08 16:33 ` Jan Beulich
2016-04-08 17:09 ` Konrad Rzeszutek Wilk
2016-04-08 17:13 ` Jan Beulich
2016-04-08 17:21 ` Wei Liu
2016-04-08 17:23 ` Konrad Rzeszutek Wilk
2016-04-08 17:27 ` Wei Liu
2016-04-08 17:21 ` Ian Jackson
2016-04-08 17:41 ` Andrew Cooper
2016-04-08 17:54 ` Jan Beulich
2016-04-11 10:50 ` Ian Jackson
2016-04-11 13:56 ` Konrad Rzeszutek Wilk
2016-04-11 14:22 ` Ian Jackson
2016-04-11 15:48 ` Jan Beulich
2016-04-11 16:25 ` Ian Jackson
2016-04-11 16:53 ` Konrad Rzeszutek Wilk
2016-04-11 17:06 ` Jan Beulich
2016-04-11 17:00 ` Jan Beulich
2016-04-11 17:13 ` Ian Jackson
2016-04-11 17:34 ` Jan Beulich
2016-04-11 17:46 ` Jan Beulich
2016-04-12 9:58 ` George Dunlap
2016-04-12 13:56 ` Konrad Rzeszutek Wilk
2016-04-12 14:38 ` George Dunlap
2016-04-12 15:00 ` Konrad Rzeszutek Wilk
2016-04-12 15:26 ` Ian Jackson
2016-04-13 4:21 ` Jan Beulich
2016-04-13 16:07 ` Ian Jackson
2016-04-14 15:13 ` George Dunlap
2016-04-14 15:59 ` Jan Beulich
2016-04-14 16:19 ` George Dunlap
2016-04-14 17:01 ` Jan Beulich
2016-04-14 18:11 ` REST MAINTAINERS feedback requested Was:Re: [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane. [and 1 more messages] Ian Jackson
2016-04-14 19:22 ` Konrad Rzeszutek Wilk
2016-04-17 7:23 ` Jan Beulich
2016-04-15 11:23 ` REST MAINTAINERS feedback requested Was:Re: [PATCH v5 01/28] HYPERCALL_version_op. New hypercall mirroring XENVER_ but sane George Dunlap
2016-04-17 7:52 ` Jan Beulich
2016-04-12 15:31 ` Jan Beulich
2016-04-12 15:17 ` Jan Beulich
2016-04-12 15:28 ` Konrad Rzeszutek Wilk
2016-04-08 17:24 ` George Dunlap
2016-04-08 17:34 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 02/28] libxc/libxl/python/xenstat/ocaml: Use new XEN_VERSION hypercall Konrad Rzeszutek Wilk
2016-03-24 21:24 ` Wei Liu
2016-03-25 13:21 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 03/28] arm/x86: Use struct virtual_region to do bug, symbol, and (x86) exception tables lookup Konrad Rzeszutek Wilk
2016-03-30 16:09 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 04/28] vmap: Add vmalloc_cb and vfree_cb Konrad Rzeszutek Wilk
2016-03-30 16:24 ` Jan Beulich
2016-03-30 16:44 ` Konrad Rzeszutek Wilk
2016-03-31 6:46 ` Jan Beulich
2016-03-31 11:49 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 05/28] xsplice: Design document Konrad Rzeszutek Wilk
2016-03-29 9:36 ` Jan Beulich
2016-03-29 20:46 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 06/28] xen/xsplice: Hypervisor implementation of XEN_XSPLICE_op Konrad Rzeszutek Wilk
2016-03-31 9:45 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 07/28] libxc: Implementation of XEN_XSPLICE_op in libxc Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 08/28] xen-xsplice: Tool to manipulate xsplice payloads Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 09/28] xsplice: Add helper elf routines Konrad Rzeszutek Wilk
2016-03-31 12:03 ` Jan Beulich
2016-04-06 1:38 ` Konrad Rzeszutek Wilk
2016-04-07 0:38 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 10/28] xsplice: Implement payload loading Konrad Rzeszutek Wilk
2016-03-31 13:45 ` Jan Beulich
2016-03-31 21:26 ` Konrad Rzeszutek Wilk
2016-04-01 9:18 ` Jan Beulich
2016-04-04 19:44 ` Konrad Rzeszutek Wilk
2016-04-05 1:57 ` Konrad Rzeszutek Wilk
2016-04-05 7:34 ` Jan Beulich
2016-04-05 15:50 ` Konrad Rzeszutek Wilk
2016-04-05 16:15 ` Jan Beulich
2016-04-05 16:45 ` Konrad Rzeszutek Wilk
2016-04-05 17:48 ` Konrad Rzeszutek Wilk
2016-04-07 0:49 ` Jan Beulich
2016-04-07 0:46 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 11/28] xsplice: Implement support for applying/reverting/replacing patches Konrad Rzeszutek Wilk
2016-04-01 13:28 ` Jan Beulich
2016-04-01 21:04 ` Konrad Rzeszutek Wilk
2016-04-04 7:07 ` Jan Beulich
2016-04-07 3:05 ` Konrad Rzeszutek Wilk [this message]
2016-04-07 15:38 ` Jan Beulich
2016-04-09 14:42 ` Konrad Rzeszutek Wilk
2016-04-11 15:38 ` Jan Beulich
2016-04-07 3:09 ` Konrad Rzeszutek Wilk
2016-04-07 15:43 ` Jan Beulich
2016-04-10 2:36 ` Konrad Rzeszutek Wilk
2016-04-10 2:45 ` Konrad Rzeszutek Wilk
2016-04-11 15:41 ` Jan Beulich
2016-04-11 23:29 ` Konrad Rzeszutek Wilk
2016-04-10 19:47 ` Is: ARM maintainers advice ..Was:Re: " Konrad Rzeszutek Wilk
2016-04-10 20:58 ` Stefano Stabellini
2016-04-11 15:44 ` Jan Beulich
2016-04-11 15:50 ` Konrad Rzeszutek Wilk
2016-04-11 16:05 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 12/28] x86/xen_hello_world.xsplice: Test payload for patching 'xen_extra_version' Konrad Rzeszutek Wilk
2016-04-01 13:33 ` Jan Beulich
2016-04-06 2:03 ` Konrad Rzeszutek Wilk
2016-04-07 1:03 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 13/28] xsplice, symbols: Implement symbol name resolution on address Konrad Rzeszutek Wilk
2016-04-01 15:11 ` Jan Beulich
2016-04-07 3:14 ` Konrad Rzeszutek Wilk
2016-04-07 15:46 ` Jan Beulich
2016-04-08 1:32 ` Konrad Rzeszutek Wilk
2016-04-08 15:21 ` Jan Beulich
2016-04-08 15:27 ` Konrad Rzeszutek Wilk
2016-04-08 15:29 ` Jan Beulich
[not found] ` <5707D68A.8090006@citrix.com>
[not found] ` <5707FA8B02000078000E6178@prv-mh.provo.novell.com>
2016-04-11 8:07 ` Ross Lagerwall
2016-03-24 20:00 ` [PATCH v5 14/28] x86, xsplice: Print payload's symbol name and payload name in backtraces Konrad Rzeszutek Wilk
2016-04-01 15:23 ` Jan Beulich
2016-04-06 2:39 ` Konrad Rzeszutek Wilk
2016-04-07 1:07 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 15/28] xsplice: Add .xsplice.hooks functions and test-case Konrad Rzeszutek Wilk
2016-04-01 15:50 ` Jan Beulich
2016-04-06 2:42 ` Konrad Rzeszutek Wilk
2016-04-06 6:39 ` Martin Pohlack
2016-04-07 1:15 ` Jan Beulich
2016-04-08 15:57 ` Ross Lagerwall
2016-04-08 17:39 ` Jan Beulich
2016-04-11 8:23 ` Ross Lagerwall
2016-04-22 13:33 ` Jan Beulich
2016-04-22 13:58 ` Jan Beulich
2016-04-22 17:32 ` Konrad Rzeszutek Wilk
2016-04-07 1:11 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 16/28] xsplice: Add support for bug frames Konrad Rzeszutek Wilk
2016-04-01 16:00 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 17/28] xsplice: Add support for exception tables Konrad Rzeszutek Wilk
2016-04-01 16:06 ` Jan Beulich
2016-04-06 14:41 ` Konrad Rzeszutek Wilk
2016-04-06 15:32 ` Andrew Cooper
2016-04-07 1:21 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 18/28] xsplice: Add support for alternatives Konrad Rzeszutek Wilk
2016-04-01 16:20 ` Jan Beulich
2016-04-07 3:11 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 19/28] build_id: Provide ld-embedded build-ids Konrad Rzeszutek Wilk
2016-04-04 12:46 ` Jan Beulich
2016-04-07 2:58 ` Konrad Rzeszutek Wilk
2016-04-08 15:49 ` Ross Lagerwall
2016-04-08 18:47 ` Konrad Rzeszutek Wilk
2016-04-08 18:54 ` Andrew Cooper
2016-04-08 19:54 ` Jan Beulich
2016-04-08 0:18 ` Konrad Rzeszutek Wilk
2016-04-08 1:52 ` Konrad Rzeszutek Wilk
2016-04-08 15:27 ` Jan Beulich
2016-04-08 17:06 ` Konrad Rzeszutek Wilk
2016-04-08 17:44 ` Jan Beulich
2016-04-08 19:23 ` Konrad Rzeszutek Wilk
2016-04-08 19:39 ` Konrad Rzeszutek Wilk
2016-04-08 20:14 ` Jan Beulich
2016-04-08 20:50 ` Konrad Rzeszutek Wilk
2016-04-08 21:11 ` Jan Beulich
2016-04-08 21:15 ` Konrad Rzeszutek Wilk
2016-04-08 15:25 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 20/28] HYPERCALL_version_op: Add VERSION_build_id to retrieve build-id Konrad Rzeszutek Wilk
2016-03-25 16:26 ` Daniel De Graaf
2016-04-04 13:35 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 21/28] libxl: info: Display build_id of the hypervisor using XEN_VERSION_build_id Konrad Rzeszutek Wilk
2016-03-25 13:25 ` Konrad Rzeszutek Wilk
2016-03-25 15:27 ` Wei Liu
2016-03-24 20:00 ` [PATCH v5 22/28] xsplice: Print build_id in keyhandler and on bootup Konrad Rzeszutek Wilk
2016-04-04 13:38 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 23/28] xsplice: Stacking build-id dependency checking Konrad Rzeszutek Wilk
2016-04-04 15:00 ` Jan Beulich
2016-04-04 20:01 ` Konrad Rzeszutek Wilk
2016-04-05 7:43 ` Jan Beulich
2016-04-08 16:15 ` Ross Lagerwall
2016-04-08 17:47 ` Jan Beulich
2016-04-06 20:05 ` Konrad Rzeszutek Wilk
2016-04-07 1:24 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 24/28] xsplice/xen_replace_world: Test-case for XSPLICE_ACTION_REPLACE Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 25/28] xsplice: Print dependency and payloads build_id in the keyhandler Konrad Rzeszutek Wilk
2016-04-04 15:03 ` Jan Beulich
2016-03-24 20:00 ` [PATCH v5 26/28] xsplice: Prevent duplicate payloads from being loaded Konrad Rzeszutek Wilk
2016-04-04 15:06 ` Jan Beulich
2016-04-04 19:52 ` Konrad Rzeszutek Wilk
2016-03-24 20:00 ` [PATCH v5 27/28] xsplice: Add support for shadow variables Konrad Rzeszutek Wilk
2016-04-04 15:18 ` Jan Beulich
2016-04-06 2:26 ` Konrad Rzeszutek Wilk
2016-04-08 15:58 ` Ross Lagerwall
2016-03-24 20:00 ` [PATCH v5 28/28] MAINTAINERS/xsplice: Add myself and Ross as the maintainers Konrad Rzeszutek Wilk
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