From: Michael Matz <matz@suse.de>
To: Andrew Haley <aph@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] [AArch64] support -mfentry feature for arm64
Date: Mon, 18 Apr 2016 17:34:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.20.1604181929170.20277@wotan.suse.de> (raw)
In-Reply-To: <57151699.6020602@redhat.com>
Hi,
On Mon, 18 Apr 2016, Andrew Haley wrote:
> >> That may not be safe. Consider an implementation which looks ahead
> >> in the instruction stream and decodes the instructions speculatively.
> >
> > It should go without saying that patching instructions is followed by
> > whatever means necessary to flush any such caches on a particular
> > implementation (here after patching the jump, after patching the rest,
> > and after patching the first insn again, i.e. three times).
>
> That doesn't necessarily help you, though, without an ISB in the reading
> thread.
I don't understand, which reading thread? We're writing, not reading
instructions. You mean other executing threads? I will happily declare
any implementation where it's impossible to safely patch the
instruction stream by flushing the respective buffers or other means
completely under control of the patching machinery, to be broken by
design. What failure mode do you envision, exactly?
Ciao,
Michael.
next prev parent reply other threads:[~2016-04-18 17:34 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-14 8:13 Li Bin
2016-03-14 8:12 ` Li Bin
2016-04-14 13:08 ` Maxim Kuvyrkov
2016-04-14 13:15 ` Andrew Pinski
2016-04-14 15:58 ` Szabolcs Nagy
2016-04-18 13:26 ` Alexander Monakov
2016-04-18 13:34 ` Ramana Radhakrishnan
2016-04-18 13:44 ` Alexander Monakov
2016-04-18 13:57 ` Ramana Radhakrishnan
2016-04-18 14:03 ` Alexander Monakov
2016-04-18 14:31 ` Szabolcs Nagy
2016-04-18 15:54 ` Alexander Monakov
2016-04-19 6:46 ` AKASHI Takahiro
2016-04-19 6:13 ` AKASHI Takahiro
2016-04-19 6:44 ` Alexander Monakov
2016-04-20 0:33 ` AKASHI Takahiro
2016-04-20 10:02 ` Szabolcs Nagy
2016-04-15 15:40 ` Michael Matz
2016-04-15 17:29 ` Alexander Monakov
2016-04-17 15:06 ` Alexander Monakov
2016-04-18 12:12 ` Michael Matz
2016-04-19 6:26 ` AKASHI Takahiro
2016-04-19 6:39 ` Alexander Monakov
2016-04-20 1:23 ` AKASHI Takahiro
2016-04-20 16:45 ` Szabolcs Nagy
2016-04-19 16:03 ` Torsten Duwe
2016-04-18 14:32 ` Andrew Haley
2016-04-18 17:13 ` Michael Matz
2016-04-18 17:17 ` Andrew Haley
2016-04-18 17:34 ` Michael Matz [this message]
2016-04-19 8:00 ` Andrew Haley
2016-04-19 13:19 ` Michael Matz
2016-04-19 13:25 ` Andrew Haley
2016-04-19 14:38 ` Pedro Alves
2016-04-19 15:02 ` Andrew Haley
2016-04-19 6:08 ` AKASHI Takahiro
-- strict thread matches above, loose matches on Subject: below --
2015-10-22 13:24 Li Bin
2015-10-22 13:53 ` Marcus Shawcroft
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