From: Ingo Molnar <mingo@kernel.org>
To: Andy Lutomirski <luto@kernel.org>,
"Paul E. McKenney" <paulmck@us.ibm.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
"Frédéric Weisbecker" <fweisbec@gmail.com>,
"Rik van Riel" <riel@redhat.com>,
"Oleg Nesterov" <oleg@redhat.com>,
"Denys Vlasenko" <vda.linux@googlemail.com>,
"Borislav Petkov" <bp@alien8.de>,
"Kees Cook" <keescook@chromium.org>,
"Brian Gerst" <brgerst@gmail.com>
Subject: Re: [RFC/INCOMPLETE 01/13] context_tracking: Add context_tracking_assert_state
Date: Wed, 17 Jun 2015 11:41:14 +0200 [thread overview]
Message-ID: <20150617094114.GA3940@gmail.com> (raw)
In-Reply-To: <1d95640676a92a5ff7382e9c87517c12ea23ccd9.1434485184.git.luto@kernel.org>
* Andy Lutomirski <luto@kernel.org> wrote:
> This will let us sprinkle sanity checks around the kernel without
> making too much of a mess.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> include/linux/context_tracking.h | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
> index 2821838256b4..0fbea4b152e1 100644
> --- a/include/linux/context_tracking.h
> +++ b/include/linux/context_tracking.h
> @@ -57,6 +57,13 @@ static inline void context_tracking_task_switch(struct task_struct *prev,
> if (context_tracking_is_enabled())
> __context_tracking_task_switch(prev, next);
> }
> +
> +static inline void context_tracking_assert_state(enum ctx_state state)
> +{
> + rcu_lockdep_assert(!context_tracking_is_enabled() ||
> + this_cpu_read(context_tracking.state) == state,
> + "context tracking state was wrong");
> +}
Please don't introduce assert() style debug check interfaces!
(And RCU should be fixed too I suspect.)
They are absolutely horrible on the brain when mixed with WARN_ON() interfaces,
which are the dominant runtime check interface in the kernel.
Instead make it something like:
#define ct_state() (this_cpu_read(context_tracking.state))
#define CT_WARN_ON(cond) \
WARN_ON(context_tracking_is_enabled() && (cond))
and then the debug checks can be written as:
CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
This is IMHO _far_ more readable than:
context_tracking_assert_state(CONTEXT_KERNEL);
ok?
(Assuming people will accept 'ct/CT' as an abbreviation for context tracking.)
Thanks,
Ingo
next prev parent reply other threads:[~2015-06-17 9:41 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-16 20:16 [RFC/INCOMPLETE 00/13] x86: Rewrite exit-to-userspace code Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 01/13] context_tracking: Add context_tracking_assert_state Andy Lutomirski
2015-06-17 9:41 ` Ingo Molnar [this message]
2015-06-17 14:15 ` Andy Lutomirski
2015-06-18 9:57 ` Ingo Molnar
2015-06-18 11:07 ` Andy Lutomirski
2015-06-18 15:52 ` Andy Lutomirski
2015-06-18 16:17 ` Ingo Molnar
2015-06-18 16:26 ` Frederic Weisbecker
2015-06-18 19:26 ` Andy Lutomirski
2015-06-17 15:27 ` Paul E. McKenney
2015-06-18 9:59 ` Ingo Molnar
2015-06-18 22:54 ` Paul E. McKenney
2015-06-19 2:19 ` Paul E. McKenney
2015-06-30 11:04 ` Ingo Molnar
2015-06-30 16:16 ` Paul E. McKenney
2015-06-16 20:16 ` [RFC/INCOMPLETE 02/13] notifiers: Assert that RCU is watching in notify_die Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 03/13] x86: Move C entry and exit code to arch/x86/entry/common.c Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 04/13] x86/traps: Assert that we're in CONTEXT_KERNEL in exception entries Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 05/13] x86/entry: Add enter_from_user_mode and use it in syscalls Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 06/13] x86/entry: Add new, comprehensible entry and exit hooks Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 07/13] x86/entry/64: Really create an error-entry-from-usermode code path Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 08/13] x86/entry/64: Migrate 64-bit syscalls to new exit hooks Andy Lutomirski
2015-06-17 10:00 ` Ingo Molnar
2015-06-17 10:02 ` Ingo Molnar
2015-06-17 14:12 ` Andy Lutomirski
2015-06-18 10:17 ` Ingo Molnar
2015-06-18 10:19 ` Ingo Molnar
2015-06-16 20:16 ` [RFC/INCOMPLETE 09/13] x86/entry/compat: Migrate compat " Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 10/13] x86/asm/entry/64: Save all regs on interrupt entry Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 11/13] x86/asm/entry/64: Simplify irq stack pt_regs handling Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 12/13] x86/asm/entry/64: Migrate error and interrupt exit work to C Andy Lutomirski
2015-06-16 20:16 ` [RFC/INCOMPLETE 13/13] x86/entry: Remove SCHEDULE_USER and asm/context-tracking.h Andy Lutomirski
2015-06-17 9:48 ` [RFC/INCOMPLETE 00/13] x86: Rewrite exit-to-userspace code Ingo Molnar
2015-06-17 10:13 ` Richard Weinberger
2015-06-17 11:04 ` Ingo Molnar
2015-06-17 14:19 ` Andy Lutomirski
2015-06-17 15:16 ` Andy Lutomirski
2015-06-18 10:14 ` Ingo Molnar
2015-06-17 10:32 ` Ingo Molnar
2015-06-17 11:14 ` Ingo Molnar
2015-06-17 14:23 ` Andy Lutomirski
2015-06-18 10:11 ` Ingo Molnar
2015-06-18 11:06 ` Andy Lutomirski
2015-06-18 16:24 ` Ingo Molnar
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