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From: "Tobin C. Harding" <me@tobin.cc>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	kernel-hardening@lists.openwall.com,
	Theodore Ts'o <tytso@mit.edu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Joe Perches <joe@perches.com>,
	Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <wilal.deacon@arm.com>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: [kernel-hardening] Re: [PATCH v7] printk: hash addresses printed with %p
Date: Tue, 31 Oct 2017 08:24:28 +1100	[thread overview]
Message-ID: <20171030212428.GR12341@eros> (raw)
In-Reply-To: <20171030162244.4f55e623@gandalf.local.home>

On Mon, Oct 30, 2017 at 04:22:44PM -0400, Steven Rostedt wrote:
> On Wed, 25 Oct 2017 14:49:34 +1100
> "Tobin C. Harding" <me@tobin.cc> wrote:
> > 
> > First, the static_key stuff.
> > 
> > DEFINE_STATIC_KEY_TRUE(no_ptr_secret) : Doesn't sleep, just a
> > declaration. 
> > 
> > if (static_branch_unlikely(&no_ptr_secret)) {} : Doesn't sleep, just
> > some assembler to jump to returning true or false.
> > 
> > static_branch_disable(&no_ptr_secret) : Doesn't sleep, just atomic read
> > and set and maybe a WARN_ONCE.
> 
> How quickly do you need static_branch_disable() executed? You could
> always pass the work off to a worker thread (that can schedule).
> 
> random_ready_callback -> initiates worker thread -> enables the static branch
> 
> -- Steve

thanks Steve, v8 and onward does away with the static branch and uses a
global boolean instead.

thanks,
Tobin.

WARNING: multiple messages have this Message-ID (diff)
From: "Tobin C. Harding" <me@tobin.cc>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	kernel-hardening@lists.openwall.com,
	"Theodore Ts'o" <tytso@mit.edu>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Tycho Andersen <tycho@docker.com>,
	"Roberts, William C" <william.c.roberts@intel.com>,
	Tejun Heo <tj@kernel.org>,
	Jordan Glover <Golden_Miller83@protonmail.ch>,
	Greg KH <gregkh@linuxfoundation.org>,
	Petr Mladek <pmladek@suse.com>, Joe Perches <joe@perches.com>,
	Ian Campbell <ijc@hellion.org.uk>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <wilal.deacon@arm.com>,
	Chris Fries <cfries@google.com>,
	Dave Weinstein <olorin@google.com>,
	Daniel Micay <danielmicay@gmail.com>,
	Djalal Harouni <tixxdz@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7] printk: hash addresses printed with %p
Date: Tue, 31 Oct 2017 08:24:28 +1100	[thread overview]
Message-ID: <20171030212428.GR12341@eros> (raw)
In-Reply-To: <20171030162244.4f55e623@gandalf.local.home>

On Mon, Oct 30, 2017 at 04:22:44PM -0400, Steven Rostedt wrote:
> On Wed, 25 Oct 2017 14:49:34 +1100
> "Tobin C. Harding" <me@tobin.cc> wrote:
> > 
> > First, the static_key stuff.
> > 
> > DEFINE_STATIC_KEY_TRUE(no_ptr_secret) : Doesn't sleep, just a
> > declaration. 
> > 
> > if (static_branch_unlikely(&no_ptr_secret)) {} : Doesn't sleep, just
> > some assembler to jump to returning true or false.
> > 
> > static_branch_disable(&no_ptr_secret) : Doesn't sleep, just atomic read
> > and set and maybe a WARN_ONCE.
> 
> How quickly do you need static_branch_disable() executed? You could
> always pass the work off to a worker thread (that can schedule).
> 
> random_ready_callback -> initiates worker thread -> enables the static branch
> 
> -- Steve

thanks Steve, v8 and onward does away with the static branch and uses a
global boolean instead.

thanks,
Tobin.

  reply	other threads:[~2017-10-30 21:24 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-23 22:33 [kernel-hardening] [PATCH v7] printk: hash addresses printed with %p Tobin C. Harding
2017-10-23 22:33 ` Tobin C. Harding
2017-10-23 23:00 ` [kernel-hardening] " Jason A. Donenfeld
2017-10-23 23:00   ` Jason A. Donenfeld
2017-10-24  0:31   ` [kernel-hardening] " Tobin C. Harding
2017-10-24  0:31     ` Tobin C. Harding
2017-10-24 11:25     ` [kernel-hardening] " Jason A. Donenfeld
2017-10-24 11:25       ` Jason A. Donenfeld
2017-10-24 20:45       ` [kernel-hardening] " Tobin C. Harding
2017-10-24 20:45         ` Tobin C. Harding
2017-10-25  3:49       ` [kernel-hardening] " Tobin C. Harding
2017-10-25  3:49         ` Tobin C. Harding
2017-10-30 20:22         ` [kernel-hardening] " Steven Rostedt
2017-10-30 20:22           ` Steven Rostedt
2017-10-30 21:24           ` Tobin C. Harding [this message]
2017-10-30 21:24             ` Tobin C. Harding
2017-10-31 14:22           ` [kernel-hardening] " Jason A. Donenfeld
2017-10-31 14:22             ` Jason A. Donenfeld
2017-10-24 19:25 ` [kernel-hardening] " Rasmus Villemoes
2017-10-24 21:52   ` Tobin C. Harding
2017-10-24 23:57   ` Tobin C. Harding
2017-10-25 19:02     ` Rasmus Villemoes
2017-10-25 19:02       ` Rasmus Villemoes
2017-10-25 22:14       ` [kernel-hardening] " Tobin C. Harding
2017-10-25 22:14         ` Tobin C. Harding
2017-10-25 16:22 ` [kernel-hardening] [lkp-robot] [printk] 7f7c60e066: BUG:KASAN:slab-out-of-bounds kernel test robot
2017-10-25 16:22   ` kernel test robot
2017-10-25 16:22   ` kernel test robot
2017-10-31  0:14   ` [kernel-hardening] " Kees Cook
2017-10-31  0:14     ` Kees Cook
2017-10-31  0:14     ` Kees Cook
2017-10-30  9:57     ` [kernel-hardening] " Ye Xiaolong
2017-10-30  9:57       ` Ye Xiaolong
2017-10-30  9:57       ` Ye Xiaolong
2017-10-31  2:39     ` [kernel-hardening] " Tobin C. Harding
2017-10-31  2:39       ` Tobin C. Harding
2017-10-31  2:47       ` [kernel-hardening] " Kees Cook
2017-10-31  2:47         ` Kees Cook
2017-10-31  2:47         ` Kees Cook
  -- strict thread matches above, loose matches on Subject: below --
2017-10-25  4:00 [kernel-hardening] Re: [PATCH v7] printk: hash addresses printed with %p Jason A. Donenfeld
2017-10-25 10:05 ` Tobin C. Harding
2017-10-25 22:27 ` Tobin C. Harding
2017-10-25 22:59   ` Jason A. Donenfeld
2017-10-25 23:11     ` Tobin C. Harding
2017-10-26  7:00     ` Greg KH
2017-10-26  9:10       ` Tobin C. Harding

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