On Tue, Jan 05, 2021 at 08:20:51AM -0800, Andy Lutomirski wrote:
> > On Jan 5, 2021, at 5:26 AM, Will Deacon wrote:
> > Sorry for the slow reply, I was socially distanced from my keyboard.
> >
> >> On Mon, Dec 28, 2020 at 04:36:11PM -0800, Andy Lutomirski wrote:
> >> On Mon, Dec 28, 2020 at 4:11
On Tue, Jan 05, 2021 at 08:20:51AM -0800, Andy Lutomirski wrote:
> > Interestingly, the architecture recently added a control bit to remove
> > this synchronisation from exception return, so if we set that then we'd
> > have a problem with SYNC_CORE and adding an ISB would be necessary
> On Jan 5, 2021, at 5:26 AM, Will Deacon wrote:
>
> Hi Andy,
>
> Sorry for the slow reply, I was socially distanced from my keyboard.
>
>> On Mon, Dec 28, 2020 at 04:36:11PM -0800, Andy Lutomirski wrote:
>> On Mon, Dec 28, 2020 at 4:11 PM Nicholas Piggin wrote:
+static inline void
Hi Andy,
Sorry for the slow reply, I was socially distanced from my keyboard.
On Mon, Dec 28, 2020 at 04:36:11PM -0800, Andy Lutomirski wrote:
> On Mon, Dec 28, 2020 at 4:11 PM Nicholas Piggin wrote:
> > > +static inline void membarrier_sync_core_before_usermode(void)
> > > +{
> > > + /*
>
From: Andy Lutomirski
> Sent: 29 December 2020 00:36
...
> I mean that the mapping from the name "sync_core" to its semantics is
> x86 only. The string "sync_core" appears in the kernel only in
> arch/x86, membarrier code, membarrier docs, and a single SGI driver
> that is x86-only. Sure, the
Excerpts from Russell King - ARM Linux admin's message of December 30, 2020
8:58 pm:
> On Wed, Dec 30, 2020 at 10:00:28AM +, Russell King - ARM Linux admin
> wrote:
>> On Wed, Dec 30, 2020 at 12:33:02PM +1000, Nicholas Piggin wrote:
>> > Excerpts from Russell King - ARM Linux admin's message
On Wed, Dec 30, 2020 at 10:00:28AM +, Russell King - ARM Linux admin wrote:
> On Wed, Dec 30, 2020 at 12:33:02PM +1000, Nicholas Piggin wrote:
> > Excerpts from Russell King - ARM Linux admin's message of December 29, 2020
> > 8:44 pm:
> > > On Tue, Dec 29, 2020 at 01:09:12PM +1000, Nicholas
On Wed, Dec 30, 2020 at 12:33:02PM +1000, Nicholas Piggin wrote:
> Excerpts from Russell King - ARM Linux admin's message of December 29, 2020
> 8:44 pm:
> > On Tue, Dec 29, 2020 at 01:09:12PM +1000, Nicholas Piggin wrote:
> >> I think it should certainly be documented in terms of what guarantees
Excerpts from Russell King - ARM Linux admin's message of December 29, 2020
8:44 pm:
> On Tue, Dec 29, 2020 at 01:09:12PM +1000, Nicholas Piggin wrote:
>> I think it should certainly be documented in terms of what guarantees
>> it provides to application, _not_ the kinds of instructions it may or
On Tue, Dec 29, 2020 at 01:09:12PM +1000, Nicholas Piggin wrote:
> I think it should certainly be documented in terms of what guarantees
> it provides to application, _not_ the kinds of instructions it may or
> may not induce the core to execute. And if existing API can't be
> re-documented
Excerpts from Andy Lutomirski's message of December 29, 2020 10:36 am:
> On Mon, Dec 28, 2020 at 4:11 PM Nicholas Piggin wrote:
>>
>> Excerpts from Andy Lutomirski's message of December 28, 2020 4:28 am:
>> > The old sync_core_before_usermode() comments said that a non-icache-syncing
>> >
Excerpts from Andy Lutomirski's message of December 29, 2020 10:56 am:
> On Mon, Dec 28, 2020 at 4:36 PM Nicholas Piggin wrote:
>>
>> Excerpts from Andy Lutomirski's message of December 29, 2020 7:06 am:
>> > On Mon, Dec 28, 2020 at 12:32 PM Mathieu Desnoyers
>> > wrote:
>> >>
>> >> - On Dec
On Mon, Dec 28, 2020 at 4:36 PM Nicholas Piggin wrote:
>
> Excerpts from Andy Lutomirski's message of December 29, 2020 7:06 am:
> > On Mon, Dec 28, 2020 at 12:32 PM Mathieu Desnoyers
> > wrote:
> >>
> >> - On Dec 28, 2020, at 2:44 PM, Andy Lutomirski l...@kernel.org wrote:
> >>
> >> > On
On Mon, Dec 28, 2020 at 4:11 PM Nicholas Piggin wrote:
>
> Excerpts from Andy Lutomirski's message of December 28, 2020 4:28 am:
> > The old sync_core_before_usermode() comments said that a non-icache-syncing
> > return-to-usermode instruction is x86-specific and that all other
> > architectures
Excerpts from Andy Lutomirski's message of December 29, 2020 7:06 am:
> On Mon, Dec 28, 2020 at 12:32 PM Mathieu Desnoyers
> wrote:
>>
>> - On Dec 28, 2020, at 2:44 PM, Andy Lutomirski l...@kernel.org wrote:
>>
>> > On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
>> > wrote:
On Mon, Dec 28, 2020 at 1:09 PM Mathieu Desnoyers
wrote:
>
> - On Dec 27, 2020, at 4:36 PM, Andy Lutomirski l...@kernel.org wrote:
>
> [...]
>
> >> You seem to have noticed odd cases on arm64 where this guarantee does not
> >> match reality. Where exactly can we find this in the code, and
Excerpts from Andy Lutomirski's message of December 28, 2020 4:28 am:
> The old sync_core_before_usermode() comments said that a non-icache-syncing
> return-to-usermode instruction is x86-specific and that all other
> architectures automatically notice cross-modified code on return to
> userspace.
On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
wrote:
>
> On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn wrote:
> > After chatting with rmk about this (but without claiming that any of
> > this is his opinion), based on the manpage, I think membarrier()
> > currently doesn't
On Mon, Dec 28, 2020 at 11:44:33AM -0800, Andy Lutomirski wrote:
> On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
> wrote:
> >
> > On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn wrote:
> > > After chatting with rmk about this (but without claiming that any of
> > > this is
- On Dec 28, 2020, at 3:24 PM, Russell King, ARM Linux
li...@armlinux.org.uk wrote:
> On Mon, Dec 28, 2020 at 11:44:33AM -0800, Andy Lutomirski wrote:
>> On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
>> wrote:
>> >
>> > On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn
- On Dec 28, 2020, at 2:44 PM, Andy Lutomirski l...@kernel.org wrote:
> On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
> wrote:
>>
>> On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn wrote:
>> > After chatting with rmk about this (but without claiming that any of
>> >
- On Dec 28, 2020, at 4:06 PM, Andy Lutomirski l...@kernel.org wrote:
> On Mon, Dec 28, 2020 at 12:32 PM Mathieu Desnoyers
> wrote:
>>
>> - On Dec 28, 2020, at 2:44 PM, Andy Lutomirski l...@kernel.org wrote:
>>
>> > On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
>> >
- On Dec 27, 2020, at 4:36 PM, Andy Lutomirski l...@kernel.org wrote:
[...]
>> You seem to have noticed odd cases on arm64 where this guarantee does not
>> match reality. Where exactly can we find this in the code, and which part
>> of the architecture manual can you point us to which
On Mon, Dec 28, 2020 at 12:32 PM Mathieu Desnoyers
wrote:
>
> - On Dec 28, 2020, at 2:44 PM, Andy Lutomirski l...@kernel.org wrote:
>
> > On Mon, Dec 28, 2020 at 11:09 AM Russell King - ARM Linux admin
> > wrote:
> >>
> >> On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn wrote:
> >> >
On Mon, Dec 28, 2020 at 07:29:34PM +0100, Jann Horn wrote:
> After chatting with rmk about this (but without claiming that any of
> this is his opinion), based on the manpage, I think membarrier()
> currently doesn't really claim to be synchronizing caches? It just
> serializes cores. So arguably
On Mon, Dec 28, 2020 at 10:30 AM Jann Horn wrote:
>
> On Mon, Dec 28, 2020 at 6:14 PM Andy Lutomirski wrote:
> > On Mon, Dec 28, 2020 at 2:25 AM Russell King - ARM Linux admin
> > wrote:
> > >
> > > On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
> > > > On Sun, Dec 27, 2020 at
On Mon, Dec 28, 2020 at 6:14 PM Andy Lutomirski wrote:
> On Mon, Dec 28, 2020 at 2:25 AM Russell King - ARM Linux admin
> wrote:
> >
> > On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
> > > On Sun, Dec 27, 2020 at 12:18 PM Mathieu Desnoyers
> > > wrote:
> > > >
> > > > -
On Mon, Dec 28, 2020 at 9:23 AM Russell King - ARM Linux admin
wrote:
>
> On Mon, Dec 28, 2020 at 09:14:23AM -0800, Andy Lutomirski wrote:
> > On Mon, Dec 28, 2020 at 2:25 AM Russell King - ARM Linux admin
> > wrote:
> > >
> > > On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
>
On Mon, Dec 28, 2020 at 09:14:23AM -0800, Andy Lutomirski wrote:
> On Mon, Dec 28, 2020 at 2:25 AM Russell King - ARM Linux admin
> wrote:
> >
> > On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
> > > On Sun, Dec 27, 2020 at 12:18 PM Mathieu Desnoyers
> > > wrote:
> > > >
> > >
On Mon, Dec 28, 2020 at 2:25 AM Russell King - ARM Linux admin
wrote:
>
> On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
> > On Sun, Dec 27, 2020 at 12:18 PM Mathieu Desnoyers
> > wrote:
> > >
> > > - On Dec 27, 2020, at 1:28 PM, Andy Lutomirski l...@kernel.org wrote:
> > >
On Sun, Dec 27, 2020 at 01:36:13PM -0800, Andy Lutomirski wrote:
> On Sun, Dec 27, 2020 at 12:18 PM Mathieu Desnoyers
> wrote:
> >
> > - On Dec 27, 2020, at 1:28 PM, Andy Lutomirski l...@kernel.org wrote:
> >
>
> > >
> > > I admit that I'm rather surprised that the code worked at all on
On Sun, Dec 27, 2020 at 12:18 PM Mathieu Desnoyers
wrote:
>
> - On Dec 27, 2020, at 1:28 PM, Andy Lutomirski l...@kernel.org wrote:
>
> >
> > I admit that I'm rather surprised that the code worked at all on arm64,
> > and I'm suspicious that it has never been very well tested. My apologies
- On Dec 27, 2020, at 1:28 PM, Andy Lutomirski l...@kernel.org wrote:
> The old sync_core_before_usermode() comments said that a non-icache-syncing
> return-to-usermode instruction is x86-specific and that all other
> architectures automatically notice cross-modified code on return to
>
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