From: "Alexander V. Tikhonov" <avtikhon@tarantool.org>
To: Igor Munkin <imun@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 19:46:35 +0300 [thread overview]
Message-ID: <X8pn6xrbagR9B4NX@tarantool.org> (raw)
In-Reply-To: <20201204162441.GC5396@tarantool.org>
Hi Igor, thanks for the patch, as I see no new degradations found [1],
patch LGTM.
[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
next prev parent reply other threads:[~2020-12-04 16:46 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 [this message]
2020-12-04 17:03 ` Igor Munkin
2020-12-07 9:37 ` Kirill Yukhin
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