From: Steven Rostedt <rostedt@goodmis.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Jason Baron <jbaron@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH 0/5 v2] [GIT PULL] x86/jump label: Paranoid checks and 2 or 5 byte nops
Date: Thu, 02 Feb 2012 17:53:10 -0500 [thread overview]
Message-ID: <1328223190.5882.128.camel@gandalf.stny.rr.com> (raw)
In-Reply-To: <4F2B090F.5020609@zytor.com>
On Thu, 2012-02-02 at 14:07 -0800, H. Peter Anvin wrote:
> Would it make more sense to keep track of three states:
>
> "Default"
> "Enabled"
> "Disabled"
Well, it is only default on start up, and every jump label is
initialized then to the ideal nop. Either at boot up, or on module load.
What's nice is that the jump label init calls call the "_static" version
of the update (arch_jump_label_transform_static()), and the
enable/disable calls the non "_static" version
(arch_jump_label_transform()). This means that we can set the "init"
flag depending on which way we got into the common code. The upper layer
only needs to know if the field is enabled or disabled. Remember this is
a x86 specific thing. Other archs do not have a different "default" nop.
There's no reason to save a "default" state, as that would require
changing the common arch layers of jump label.
-- Steve
next prev parent reply other threads:[~2012-02-02 22:53 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-28 16:09 [PATCH 0/5 v2] [GIT PULL] x86/jump label: Paranoid checks and 2 or 5 byte nops Steven Rostedt
2012-01-28 16:09 ` [PATCH 1/5 v2] x86/jump-label: Use best default nops for inital jump label calls Steven Rostedt
2012-01-28 16:09 ` [PATCH 2/5 v2] x86/jump-label: Do not bother updating nops if they are correct Steven Rostedt
2012-01-28 16:09 ` [PATCH 3/5 v2] x86/jump-label: Add safety checks to jump label conversions Steven Rostedt
2012-01-28 16:09 ` [PATCH 4/5 v2] jump labels: Add infrastructure to update jump labels at compile time Steven Rostedt
2012-01-28 16:09 ` [PATCH 5/5 v2] x86/jump labels: Use etiher 5 byte or 2 byte jumps Steven Rostedt
2012-01-30 14:48 ` [PATCH 0/5 v2] [GIT PULL] x86/jump label: Paranoid checks and 2 or 5 byte nops Ingo Molnar
2012-01-30 15:07 ` Steven Rostedt
2012-01-31 19:48 ` Ingo Molnar
2012-02-01 5:08 ` Steven Rostedt
2012-02-01 8:05 ` Ingo Molnar
2012-02-01 13:20 ` Steven Rostedt
2012-02-01 15:21 ` Steven Rostedt
2012-02-02 13:51 ` Ingo Molnar
2012-02-02 14:10 ` H. Peter Anvin
2012-02-02 14:31 ` Steven Rostedt
2012-02-02 22:04 ` Steven Rostedt
2012-02-02 22:07 ` H. Peter Anvin
2012-02-02 22:53 ` Steven Rostedt [this message]
2012-02-03 7:36 ` Ingo Molnar
2012-02-03 13:31 ` Steven Rostedt
2012-02-05 11:47 ` Ingo Molnar
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