[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <CALCETrUXPXCff6mD29fbK74y=UX_YYEHbuZA_LEiamM6pJeN+A@mail.gmail.com>
Date: Mon, 16 Jun 2014 15:00:53 -0700
From: Andy Lutomirski <luto@...capital.net>
To: "H. Peter Anvin" <hpa@...or.com>
Cc: Richard Weinberger <richard@....at>, X86 ML <x86@...nel.org>,
Toralf Förster <toralf.foerster@....de>,
Eric Paris <eparis@...hat.com>,
Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: 3.15: kernel BUG at kernel/auditsc.c:1525!
On Mon, Jun 16, 2014 at 2:58 PM, H. Peter Anvin <hpa@...or.com> wrote:
>>
>> For 64-bit, I want to do this instead:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=x86/seccomp-fastpath&id=a5ec2d7af2c54b55fc7201fa662138b53fbbda39
>>
>> I see no reason why the 64-bit badsys code needs its own code path at
>> all. I haven't sent it yet because AFAICT it doesn't fix any bug, and
>> the series it's a part of isn't ready.
>>
>> I'm also contemplating rewriting the 64-bit syscall entry work path in C.
>>
>
> Cute... although it still leaves an extra branch for the badsys. It
> might perform better than a cmov, but it might not.
I bet that the branch is faster in most cases -- I'd be somewhat
surprised if CPUs can speculate through a cmov, and that value is
needed for control flow almost immediately.
--Andy
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists