linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@amacapital.net>
Cc: x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Oleg Nesterov <oleg@redhat.com>, Tony Luck <tony.luck@intel.com>,
	Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH v4 5/5] x86, traps: Add ist_begin_non_atomic and ist_end_non_atomic
Date: Mon, 24 Nov 2014 16:54:44 +0100	[thread overview]
Message-ID: <20141124155444.GC20296@pd.tnic> (raw)
In-Reply-To: <7ddd4ff60524d065af84b9d70b1128967b37fa7b.1416604491.git.luto@amacapital.net>

On Fri, Nov 21, 2014 at 01:26:11PM -0800, Andy Lutomirski wrote:
> In some IST handlers, if the interrupt came from user mode,
> we can safely enable preemption.  Add helpers to do it safely.
> 
> This is intended to be used my the memory failure code in
> do_machine_check.
> 
> Signed-off-by: Andy Lutomirski <luto@amacapital.net>
> ---
>  arch/x86/include/asm/traps.h |  2 ++
>  arch/x86/kernel/traps.c      | 38 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
> index eb16a61bfd06..04ba537fc721 100644
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -112,6 +112,8 @@ asmlinkage void mce_threshold_interrupt(void);
>  
>  extern enum ctx_state ist_enter(struct pt_regs *regs);
>  extern void ist_exit(struct pt_regs *regs, enum ctx_state prev_state);
> +extern void ist_begin_non_atomic(struct pt_regs *regs);
> +extern void ist_end_non_atomic(void);
>  
>  /* Interrupts/Exceptions */
>  enum {
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 6a02760df7b4..2b5f2e038e3f 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -140,6 +140,44 @@ void ist_exit(struct pt_regs *regs, enum ctx_state prev_state)
>  		rcu_nmi_exit();
>  }
>  
> +/**
> + * ist_begin_non_atomic() - begin a non-atomic section in an IST exception
> + * @regs:	regs passed to the IST exception handler
> + *
> + * IST exception handlers normally cannot schedule.  As a special
> + * exception, if the exception interrupted userspace code (i.e.
> + * user_mode_vm(regs) would return true) and the exception was not
> + * a double fault, it can be safe to schedule.  ist_begin_non_atomic()
> + * begins a non-atomic section within an ist_enter()/ist_exit() region.
> + * Callers are responsible for enabling interrupts themselves inside
> + * the non-atomic section, and callers must call is_end_non_atomic()
> + * before ist_exit().
> + */

Ok, I guess this is is fine, albeit a bit circumstantial:

I need to do

	ist_enter()
	ist_begin_non_atomic()

In here, I still need to do

	if (user_mode_vm()) {
		# do non-atomic stuff
	}

AFAICT, right?

	ist_end_non_atomic()
	ist_exit()

and this whole fun for the context tracking exception_enter/_exit()
calls.

Acked-by: Borislav Petkov <bp@suse.de>

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

  reply	other threads:[~2014-11-24 15:54 UTC|newest]

Thread overview: 72+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-11-21 21:26 [PATCH v4 0/5] x86: Rework IST interrupts Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 1/5] uprobes, x86: Fix _TIF_UPROBE vs _TIF_NOTIFY_RESUME Andy Lutomirski
2014-11-22 16:55   ` Borislav Petkov
2014-11-24 17:58     ` Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context Andy Lutomirski
2014-11-21 21:32   ` Andy Lutomirski
2014-11-21 22:07     ` Paul E. McKenney
2014-11-21 22:19       ` Andy Lutomirski
2014-11-21 22:55         ` Paul E. McKenney
2014-11-21 23:06           ` Andy Lutomirski
2014-11-21 23:38             ` Paul E. McKenney
2014-11-22  2:00               ` Andy Lutomirski
2014-11-22  4:20                 ` Paul E. McKenney
2014-11-22  5:53                   ` Andy Lutomirski
2014-11-22 23:41                     ` Paul E. McKenney
2014-11-24 20:22                       ` Andy Lutomirski
2014-11-24 20:54                         ` Paul E. McKenney
2014-11-24 21:02                           ` Andy Lutomirski
2014-11-24 21:35                             ` Paul E. McKenney
2014-11-24 22:34                               ` Paul E. McKenney
2014-11-24 22:36                                 ` Andy Lutomirski
2014-11-24 22:57                                   ` Paul E. McKenney
2014-11-24 23:31                                     ` Paul E. McKenney
2014-11-24 23:35                                       ` Andy Lutomirski
2014-11-24 23:50                                         ` Paul E. McKenney
2014-11-24 23:52                                           ` Andy Lutomirski
2014-11-25 18:58                                             ` Borislav Petkov
2014-11-25 19:16                                               ` Paul E. McKenney
2014-12-11  0:22                                               ` Tony Luck
2014-12-11  0:24                                                 ` Andy Lutomirski
2015-01-05 21:46                                                   ` Tony Luck
2015-01-05 21:54                                                     ` Andy Lutomirski
2015-01-06  0:44                                                       ` [PATCH] x86, mce: Get rid of TIF_MCE_NOTIFY and associated mce tricks Luck, Tony
2015-01-06  1:01                                                         ` Andy Lutomirski
2015-01-06 18:00                                                           ` Luck, Tony
2015-01-07 12:13                                                             ` Borislav Petkov
2015-01-07 15:51                                                               ` Andy Lutomirski
2015-01-07 15:58                                                                 ` Borislav Petkov
2015-01-07 16:12                                                                 ` Paul E. McKenney
2014-11-25 17:13                                           ` [PATCH v4 2/5] x86, traps: Track entry into and exit from IST context Paul E. McKenney
2014-11-27  7:03                                           ` Lai Jiangshan
2014-11-27 16:46                                             ` Paul E. McKenney
2014-11-24 21:27                           ` Paul E. McKenney
2014-11-21 22:20       ` Frederic Weisbecker
2014-11-21 22:00   ` Paul E. McKenney
2014-11-22 17:20   ` Borislav Petkov
2014-11-24 19:48     ` Andy Lutomirski
2015-01-22 21:52   ` Sasha Levin
2015-01-23 17:58     ` Andy Lutomirski
2015-01-23 18:04       ` Borislav Petkov
2015-01-23 18:34         ` Andy Lutomirski
2015-01-23 20:48           ` Sasha Levin
2015-01-24  1:25             ` Andy Lutomirski
2015-01-28 16:33               ` Andy Lutomirski
2015-01-28 17:48                 ` Paul E. McKenney
2015-01-28 21:02                   ` Andy Lutomirski
2015-01-30 19:57                     ` Sasha Levin
2015-01-31  1:28                       ` Sasha Levin
2015-01-31  3:12                         ` Andy Lutomirski
2015-01-31 12:50                           ` Andy Lutomirski
2015-01-31 13:01                         ` [PATCH] x86, traps: Fix ist_enter from userspace Andy Lutomirski
2015-01-31 15:09                           ` Sasha Levin
2015-01-31 16:18                           ` Paul E. McKenney
2015-02-01  2:17                             ` Andy Lutomirski
2015-02-04  6:01                           ` [tip:x86/asm] " tip-bot for Andy Lutomirski
2014-11-21 21:26 ` [PATCH v4 3/5] x86, entry: Switch stacks on a paranoid entry " Andy Lutomirski
2014-11-24 15:55   ` Borislav Petkov
2014-11-21 21:26 ` [PATCH v4 4/5] x86: Clean up current_stack_pointer Andy Lutomirski
2014-11-24 11:39   ` Borislav Petkov
2014-11-21 21:26 ` [PATCH v4 5/5] x86, traps: Add ist_begin_non_atomic and ist_end_non_atomic Andy Lutomirski
2014-11-24 15:54   ` Borislav Petkov [this message]
2014-11-24 19:52     ` Andy Lutomirski

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20141124155444.GC20296@pd.tnic \
    --to=bp@alien8.de \
    --cc=andi@firstfloor.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=luto@amacapital.net \
    --cc=oleg@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tony.luck@intel.com \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).