From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
"H. Peter Anvin" <hpa@zytor.com>, Oleg Nesterov <oleg@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86/asm/entry/64: better check for canonical address
Date: Thu, 23 Apr 2015 17:49:26 +0200 [thread overview]
Message-ID: <20150423154926.GM28327@pd.tnic> (raw)
In-Reply-To: <CALCETrUm4qJrEg0SLpFUJB=iH0Sxo+_Ptd-esA=v9D1_F33MrQ@mail.gmail.com>
On Thu, Apr 23, 2015 at 08:41:15AM -0700, Andy Lutomirski wrote:
> I was rather vague there. Let me try again:
>
> If anyone in the AMD camp really cared, we could add a new bug flag
> X86_BUG_SYSRET_NEEDS_CANONICAL_RCX and set it on Intel chips only, so
> we could use alternatives to patch out the check when running on
> sensible AMD hardware. This would speed the slow path up by a couple
> of cycles on AMD chips.
>
> Does that make more sense? We could call it
> X86_BUG_SYSRET_NEEDS_CANONICAL_RIP if that makes more sense.
Actually "...NEEDS_CANONICAL_RCX" makes more sense as this is what we're
going to patch out eventually, if it makes sense - the RIP canonicalness
test is being done as part of SYSRET, just RCX is not being tested.
Tell you what - how about I perf stat this first by commenting out that
couple of instructions on AMD to see whether it brings anything.
Got an idea for a workload other than a kernel build? :-)
Although a kernel build should do a lot of syscalls too...
Thanks.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
next prev parent reply other threads:[~2015-04-23 15:49 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-21 16:27 [PATCH] x86/asm/entry/64: better check for canonical address Denys Vlasenko
2015-04-21 18:08 ` Andy Lutomirski
2015-04-23 15:10 ` Borislav Petkov
2015-04-23 15:41 ` Andy Lutomirski
2015-04-23 15:49 ` Borislav Petkov [this message]
2015-04-23 15:52 ` Andy Lutomirski
2015-04-22 14:11 ` [tip:x86/asm] x86/asm/entry/64: Implement better check for canonical addresses tip-bot for Denys Vlasenko
-- strict thread matches above, loose matches on Subject: below --
2015-03-26 12:42 [PATCH] x86/asm/entry/64: better check for canonical address Denys Vlasenko
2015-03-26 18:45 ` Andy Lutomirski
2015-03-27 8:57 ` Borislav Petkov
2015-03-30 14:27 ` Denys Vlasenko
2015-03-30 14:30 ` Andy Lutomirski
2015-03-30 14:45 ` Andy Lutomirski
2015-03-27 8:11 ` Ingo Molnar
2015-03-27 10:45 ` Denys Vlasenko
2015-03-27 11:17 ` Ingo Molnar
2015-03-27 11:28 ` Brian Gerst
2015-03-27 11:34 ` Ingo Molnar
2015-03-27 12:14 ` Denys Vlasenko
2015-03-27 12:16 ` Ingo Molnar
2015-03-27 12:31 ` Denys Vlasenko
2015-03-28 9:11 ` Ingo Molnar
2015-03-29 19:36 ` Denys Vlasenko
2015-03-29 21:12 ` Andy Lutomirski
2015-03-29 21:46 ` Denys Vlasenko
2015-03-31 16:43 ` Ingo Molnar
2015-03-31 17:08 ` Andy Lutomirski
2015-03-31 17:31 ` Denys Vlasenko
2015-03-27 11:27 ` Brian Gerst
2015-03-27 11:31 ` Ingo Molnar
2015-03-27 21:37 ` Andy Lutomirski
2015-04-02 17:37 ` Denys Vlasenko
2015-04-02 18:10 ` Ingo Molnar
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