From: Igor Munkin <imun@tarantool.org>
To: "Alexander V. Tikhonov" <avtikhon@tarantool.org>
Cc: tarantool-patches@dev.tarantool.org
Subject: Re: [Tarantool-patches] [PATCH luajit] x64: Fix __call metamethod return dispatch.
Date: Fri, 4 Dec 2020 20:03:59 +0300 [thread overview]
Message-ID: <20201204170359.GD5396@tarantool.org> (raw)
In-Reply-To: <X8pn6xrbagR9B4NX@tarantool.org>
Sasha,
On 04.12.20, Alexander V. Tikhonov wrote:
> Hi Igor, thanks for the patch, as I see no new degradations found [1],
> patch LGTM.
Great, thanks!
Kirill, please proceed with the patch.
>
> [1] - https://gitlab.com/tarantool/tarantool/-/pipelines/225349795
>
> On Fri, Dec 04, 2020 at 07:24:41PM +0300, Igor Munkin wrote:
> > Sasha,
> >
> > Could you please confirm whether CI is OK?
> >
> > On 04.12.20, Igor Munkin wrote:
> > > From: Mike Pall <mike>
> > >
> > > After linking new cframe to the chain KBASEa still stores the address of
> > > the previous one. If the execution proceeds to <lj_vmeta_call> KBASE
> > > value (i.e. low 32 bits of the stored address) might be equal to the
> > > current BASE address value so the execution takes the invalid path. Such
> > > address clashing occurs only on x86_64 platform with disabled LJ_GC64,
> > > so 64-bit registers have to be compared in x64 build.
> > >
> > > NB: Though there is only 32-bit load to restore BASE value prior to the
> > > comparison, the high 32 bits of RDX are reset to zeros, according to x86
> > > long mode semantics.
> > >
> > > Igor Munkin:
> > > * backported the original patch to tarantool/luajit repo
> > > * extended the original commit message with the rationale
> > >
> > > For more info and explanation see LuaJIT/LuaJIT#636.
> > >
> > > Relates to tarantool/tarantool#4518
> > > Relates to tarantool/tarantool#4649
> > >
> > > Signed-off-by: Igor Munkin <imun@tarantool.org>
> > > ---
> > >
> > > Issues:
> > > * https://github.com/tarantool/tarantool/issues/4518
> > > * https://github.com/tarantool/tarantool/issues/4649
> > > Branch:
> > > * https://github.com/tarantool/luajit/tree/imun/gh-4518-cmp-64-bit-regs-in-vmeta-call
> > >
> > > CI is kinda green, considering C6 EOL and the corresponding failures:
> > > * https://gitlab.com/tarantool/tarantool/-/pipelines/225349795
> > >
> > > @ChangeLog:
> > > * Fixed address clashing occurring while __call metamethod dispatching
> > > (gh-4518, gh-4649).
> > >
> > > Unfortunately, there is neither test nor reproducer for this failure, so
> > > we'll know that the patch works only on production installations.
> > >
> >
> > <snipped>
> >
> > >
> >
> > --
> > Best regards,
> > IM
--
Best regards,
IM
next prev parent reply other threads:[~2020-12-04 17:04 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-04 13:42 Igor Munkin
2020-12-04 14:14 ` Sergey Kaplun
2020-12-04 14:35 ` Igor Munkin
2020-12-04 15:40 ` Sergey Ostanevich
2020-12-04 16:22 ` Igor Munkin
2020-12-04 16:24 ` Igor Munkin
2020-12-04 16:46 ` Alexander V. Tikhonov
2020-12-04 17:03 ` Igor Munkin [this message]
2020-12-07 9:37 ` Kirill Yukhin
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