From: Michael Matz <matz@suse.de>
To: Alexander Monakov <amonakov@ispras.ru>
Cc: Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>,
Li Bin <huawei.libin@huawei.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
Marcus Shawcroft <marcus.shawcroft@arm.com>,
richard.earnshaw@arm.com, andrew.wafaa@arm.com,
szabolcs.nagy@arm.com, masami.hiramatsu.pt@hitachi.com,
geoff@infradead.org, takahiro.akashi@linaro.org,
guohanjun@huawei.com, felix.yang@huawei.com,
jiangjiji@huawei.com
Subject: Re: [PATCH] [AArch64] support -mfentry feature for arm64
Date: Mon, 18 Apr 2016 12:12:00 -0000 [thread overview]
Message-ID: <alpine.LSU.2.20.1604181408270.20277@wotan.suse.de> (raw)
In-Reply-To: <alpine.LNX.2.20.1604171752300.26109@monopod.intra.ispras.ru>
Hi,
On Sun, 17 Apr 2016, Alexander Monakov wrote:
> I've noticed an issue in my (and probably Michael's) solution: if
> there's a thread that made it past the first nop, but is still executing
> the nop pad, it's unsafe to replace the nops. To solve that, it
> suffices to have a forward branch in place of the first nop to begin
> with (i.e. have the compiler emit it).
True. I wonder if the generic solution in GCC should do that always or if
the patch infrastructure should do that to enable more freedom like doing
this:
> But if Szabolcs' two-instruction
> sequence in the adjacent subthread is sufficient, this is moot.
. It can also be solved by having just one NOP after the function label,
and a number of them before, then no thread can be in the nop pad. That
seems to indicate that GCC should not try to be too clever and simply
leave the specified number of nops before and after the function label,
leaving safety measures to the patching infrastructure.
Ciao,
Michael.
next prev parent reply other threads:[~2016-04-18 12:12 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 [this message]
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
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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