Linux-mediatek Archive on lore.kernel.org
 help / color / Atom feed
From: Neal Liu <neal.liu@mediatek.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>,
	linux-tegra@vger.kernel.org, wsd_upstream@mediatek.com,
	linux-pm@vger.kernel.org,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	linux-kernel@vger.kernel.org,
	Jonathan Hunter <jonathanh@nvidia.com>,
	linux-acpi@vger.kernel.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Neal Liu <neal.liu@mediatek.com>,
	Sami Tolvanen <samitolvanen@google.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	linux-mediatek@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org, Len Brown <lenb@kernel.org>
Subject: Re: [PATCH] cpuidle: change enter_s2idle() prototype
Date: Wed, 1 Jul 2020 10:39:41 +0800
Message-ID: <1593571181.7383.5.camel@mtkswgap22> (raw)
In-Reply-To: <9963896.lEaLCsxmBZ@kreacher>

On Mon, 2020-06-29 at 17:17 +0200, Rafael J. Wysocki wrote:
> On Monday, June 29, 2020 11:05:40 AM CEST Neal Liu wrote:
> > Control Flow Integrity(CFI) is a security mechanism that disallows
> > changes to the original control flow graph of a compiled binary,
> > making it significantly harder to perform such attacks.
> > 
> > init_state_node() assigns same function pointer to idle_state->enter
> > and idle_state->enter_s2idle. This definitely causes CFI failure
> > when calling either enter() or enter_s2idle().
> > 
> > Align enter_s2idle() with enter() function prototype to fix CFI
> > failure.
> 
> That needs to be documented somewhere close to the definition of the
> callbacks in question.
> 
> Otherwise it is completely unclear why this is a good idea.
> 

The problem is, init_state_mode() assign same function callback to
different function pointer declarations.

static int init_state_node(struct cpuidle_state *idle_state,
                           const struct of_device_id *matches,
                           struct device_node *state_node)
{
...
        idle_state->enter = match_id->data;
...
        idle_state->enter_s2idle = match_id->data;
}

Function declarations:

struct cpuidle_state {
...
        int (*enter)    (struct cpuidle_device *dev,
                        struct cpuidle_driver *drv,
                        int index);

        void (*enter_s2idle) (struct cpuidle_device *dev,
                              struct cpuidle_driver *drv,
                              int index);
};

In this case, either enter() or enter_s2idle() would cause CFI check
failed since they use same callee.

We try to align function prototype of enter() since it needs return
value for some use cases. The return value of enter_s2idle() is no need
currently.


> > Signed-off-by: Neal Liu <neal.liu@mediatek.com>
> > ---
> >  drivers/acpi/processor_idle.c   |    6 ++++--
> >  drivers/cpuidle/cpuidle-tegra.c |    8 +++++---
> >  drivers/idle/intel_idle.c       |    6 ++++--
> >  include/linux/cpuidle.h         |    6 +++---
> >  4 files changed, 16 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > index 75534c5..6ffb6c9 100644
> > --- a/drivers/acpi/processor_idle.c
> > +++ b/drivers/acpi/processor_idle.c
> > @@ -655,8 +655,8 @@ static int acpi_idle_enter(struct cpuidle_device *dev,
> >  	return index;
> >  }
> >  
> > -static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> > -				   struct cpuidle_driver *drv, int index)
> > +static int acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> > +				  struct cpuidle_driver *drv, int index)
> >  {
> >  	struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu);
> >  
> > @@ -674,6 +674,8 @@ static void acpi_idle_enter_s2idle(struct cpuidle_device *dev,
> >  		}
> >  	}
> >  	acpi_idle_do_entry(cx);
> > +
> > +	return 0;
> >  }
> >  
> >  static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr,
> > diff --git a/drivers/cpuidle/cpuidle-tegra.c b/drivers/cpuidle/cpuidle-tegra.c
> > index 1500458..a12fb14 100644
> > --- a/drivers/cpuidle/cpuidle-tegra.c
> > +++ b/drivers/cpuidle/cpuidle-tegra.c
> > @@ -253,11 +253,13 @@ static int tegra_cpuidle_enter(struct cpuidle_device *dev,
> >  	return err ? -1 : index;
> >  }
> >  
> > -static void tegra114_enter_s2idle(struct cpuidle_device *dev,
> > -				  struct cpuidle_driver *drv,
> > -				  int index)
> > +static int tegra114_enter_s2idle(struct cpuidle_device *dev,
> > +				 struct cpuidle_driver *drv,
> > +				 int index)
> >  {
> >  	tegra_cpuidle_enter(dev, drv, index);
> > +
> > +	return 0;
> >  }
> >  
> >  /*
> > diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> > index f449584..b178da3 100644
> > --- a/drivers/idle/intel_idle.c
> > +++ b/drivers/idle/intel_idle.c
> > @@ -175,13 +175,15 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
> >   * Invoked as a suspend-to-idle callback routine with frozen user space, frozen
> >   * scheduler tick and suspended scheduler clock on the target CPU.
> >   */
> > -static __cpuidle void intel_idle_s2idle(struct cpuidle_device *dev,
> > -					struct cpuidle_driver *drv, int index)
> > +static __cpuidle int intel_idle_s2idle(struct cpuidle_device *dev,
> > +				       struct cpuidle_driver *drv, int index)
> >  {
> >  	unsigned long eax = flg2MWAIT(drv->states[index].flags);
> >  	unsigned long ecx = 1; /* break on interrupt flag */
> >  
> >  	mwait_idle_with_hints(eax, ecx);
> > +
> > +	return 0;
> >  }
> >  
> >  /*
> > diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
> > index ec2ef63..bee10c0 100644
> > --- a/include/linux/cpuidle.h
> > +++ b/include/linux/cpuidle.h
> > @@ -66,9 +66,9 @@ struct cpuidle_state {
> >  	 * suspended, so it must not re-enable interrupts at any point (even
> >  	 * temporarily) or attempt to change states of clock event devices.
> >  	 */
> > -	void (*enter_s2idle) (struct cpuidle_device *dev,
> > -			      struct cpuidle_driver *drv,
> > -			      int index);
> > +	int (*enter_s2idle)(struct cpuidle_device *dev,
> > +			    struct cpuidle_driver *drv,
> > +			    int index);
> >  };
> >  
> >  /* Idle State Flags */
> > -- 
> > 1.7.9.5
> > 
> 
> 
> 
> 

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

  reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-29  9:05 cpuidle: Fix CFI failure Neal Liu
2020-06-29  9:05 ` [PATCH] cpuidle: change enter_s2idle() prototype Neal Liu
2020-06-29 15:17   ` Rafael J. Wysocki
2020-07-01  2:39     ` Neal Liu [this message]
2020-07-01  5:50       ` Daniel Lezcano

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=1593571181.7383.5.camel@mtkswgap22 \
    --to=neal.liu@mediatek.com \
    --cc=daniel.lezcano@linaro.org \
    --cc=jacob.jun.pan@linux.intel.com \
    --cc=jonathanh@nvidia.com \
    --cc=lenb@kernel.org \
    --cc=linux-acpi@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-tegra@vger.kernel.org \
    --cc=matthias.bgg@gmail.com \
    --cc=rjw@rjwysocki.net \
    --cc=samitolvanen@google.com \
    --cc=thierry.reding@gmail.com \
    --cc=wsd_upstream@mediatek.com \
    /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

Linux-mediatek Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mediatek/0 linux-mediatek/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mediatek linux-mediatek/ https://lore.kernel.org/linux-mediatek \
		linux-mediatek@lists.infradead.org
	public-inbox-index linux-mediatek

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-mediatek


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git