From: "H. Peter Anvin" <hpa@zytor.com>
To: Andy Lutomirski <luto@amacapital.net>,
Denys Vlasenko <vda.linux@googlemail.com>
Cc: Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Brian Gerst <brgerst@gmail.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Ingo Molnar <mingo@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
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>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue
Date: Fri, 24 Apr 2015 14:45:04 -0700 [thread overview]
Message-ID: <553AB960.8080000@zytor.com> (raw)
In-Reply-To: <CALCETrVjcw9TAKm+GGzJtzUUPpovJYZMn4vXc=cYG+s5B57h5Q@mail.gmail.com>
On 04/24/2015 01:50 PM, Andy Lutomirski wrote:
>>
>> Exactly my feeling. What are you trying to save? About four CPU
>> cycles of checking %ss != __KERNEL_DS on each switch_to?
>> That's not worth bothering about. Your last patch seems to be perfect.
>
> We'll have to do the write to ss almost every time an AMD CPU sleeps
> in a syscall. Maybe that's still not a big deal.
>
Once you're sleeping anyway, I don't think so.
-hpa
next prev parent reply other threads:[~2015-04-24 21:45 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-24 2:15 [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue Andy Lutomirski
2015-04-24 2:18 ` Andy Lutomirski
2015-04-26 12:34 ` Denys Vlasenko
2015-04-24 3:58 ` Brian Gerst
2015-04-24 9:59 ` Denys Vlasenko
2015-04-24 10:59 ` Borislav Petkov
2015-04-24 19:58 ` Borislav Petkov
2015-04-24 11:27 ` Denys Vlasenko
2015-04-24 12:00 ` Brian Gerst
2015-04-24 16:25 ` Linus Torvalds
2015-04-24 17:33 ` Brian Gerst
2015-04-24 17:41 ` Linus Torvalds
2015-04-24 17:57 ` Brian Gerst
2015-04-24 20:21 ` Andy Lutomirski
2015-04-24 20:46 ` Denys Vlasenko
2015-04-24 20:50 ` Andy Lutomirski
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin
2015-04-24 21:45 ` H. Peter Anvin [this message]
2015-04-24 21:45 ` H. Peter Anvin
2015-04-25 2:17 ` Denys Vlasenko
2015-04-26 23:36 ` Andy Lutomirski
2015-04-24 20:53 ` Linus Torvalds
2015-04-25 21:12 ` Borislav Petkov
2015-04-26 11:22 ` perf numbers (was: Re: [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue) Borislav Petkov
2015-04-26 23:39 ` [PATCH] x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue Andy Lutomirski
2015-04-27 8:53 ` Borislav Petkov
2015-04-27 10:07 ` Denys Vlasenko
2015-04-27 10:09 ` Borislav Petkov
2015-04-27 11:35 ` Borislav Petkov
2015-04-27 12:08 ` Denys Vlasenko
2015-04-27 12:48 ` Borislav Petkov
2015-04-27 14:57 ` Linus Torvalds
2015-04-27 15:06 ` Linus Torvalds
2015-04-27 15:35 ` Borislav Petkov
2015-04-27 15:46 ` Borislav Petkov
2015-04-27 15:56 ` Andy Lutomirski
2015-04-27 16:04 ` Brian Gerst
2015-04-27 16:10 ` Denys Vlasenko
2015-04-27 16:00 ` Linus Torvalds
2015-04-27 16:40 ` Borislav Petkov
2015-04-27 18:14 ` Linus Torvalds
2015-04-27 18:38 ` Borislav Petkov
2015-04-27 18:47 ` Linus Torvalds
2015-04-27 18:53 ` Borislav Petkov
2015-04-27 19:59 ` H. Peter Anvin
2015-04-27 20:03 ` Borislav Petkov
2015-04-27 20:14 ` H. Peter Anvin
2015-04-28 15:55 ` Borislav Petkov
2015-04-28 16:28 ` Linus Torvalds
2015-04-28 16:58 ` Borislav Petkov
2015-04-28 17:16 ` Linus Torvalds
2015-04-28 18:38 ` Borislav Petkov
2015-04-30 21:39 ` H. Peter Anvin
2015-04-30 23:23 ` H. Peter Anvin
2015-05-01 9:03 ` Borislav Petkov
2015-05-03 11:51 ` Borislav Petkov
2015-04-27 19:11 ` Borislav Petkov
2015-04-27 19:21 ` Denys Vlasenko
2015-04-27 19:45 ` Borislav Petkov
2015-04-28 13:40 ` Borislav Petkov
2015-04-27 16:12 ` Denys Vlasenko
2015-04-27 18:12 ` Linus Torvalds
2015-04-27 18:47 ` Borislav Petkov
2015-04-27 14:39 ` Borislav Petkov
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