diff mbox

powercap/rapl: prevent overridding bits outside of the mask

Message ID 20170601092150.4474-1-adam.lessnau@intel.com (mailing list archive)
State Mainlined
Delegated to: Rafael Wysocki
Headers show

Commit Message

Adam Lessnau June 1, 2017, 9:21 a.m. UTC
Fixes wrong bits shift operation in the rapl_write_data_raw function, which
might cause overridding bits outside of the mask.

For example, writing new TIME_WINDOW1 value can override POWER_LIMIT1.

Signed-off-by: Adam Lessnau <adam.lessnau@intel.com>
---
 drivers/powercap/intel_rapl.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

Comments

Rafael J. Wysocki June 27, 2017, 12:17 a.m. UTC | #1
On Thursday, June 01, 2017 11:21:50 AM Adam Lessnau wrote:
> Fixes wrong bits shift operation in the rapl_write_data_raw function, which
> might cause overridding bits outside of the mask.
> 
> For example, writing new TIME_WINDOW1 value can override POWER_LIMIT1.
> 
> Signed-off-by: Adam Lessnau <adam.lessnau@intel.com>

Jacob, any comments?

> ---
>  drivers/powercap/intel_rapl.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
> index 3c71f608b444..6dc27afb8527 100644
> --- a/drivers/powercap/intel_rapl.c
> +++ b/drivers/powercap/intel_rapl.c
> @@ -887,7 +887,9 @@ static int rapl_write_data_raw(struct rapl_domain *rd,
>  
>  	cpu = rd->rp->lead_cpu;
>  	bits = rapl_unit_xlate(rd, rp->unit, value, 1);
> -	bits |= bits << rp->shift;
> +	bits <<= rp->shift;
> +	bits &= rp->mask;
> +
>  	memset(&ma, 0, sizeof(ma));
>  
>  	ma.msr_no = rd->msrs[rp->id];
>
Jacob Pan June 27, 2017, 4:25 p.m. UTC | #2
On Tue, 27 Jun 2017 02:17:32 +0200
"Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:

> On Thursday, June 01, 2017 11:21:50 AM Adam Lessnau wrote:
> > Fixes wrong bits shift operation in the rapl_write_data_raw
> > function, which might cause overridding bits outside of the mask.
> > 
> > For example, writing new TIME_WINDOW1 value can override
> > POWER_LIMIT1.
> > 
> > Signed-off-by: Adam Lessnau <adam.lessnau@intel.com>  
> 
> Jacob, any comments?
> 
Looks like a good fix. Thanks.
> > ---
> >  drivers/powercap/intel_rapl.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/powercap/intel_rapl.c
> > b/drivers/powercap/intel_rapl.c index 3c71f608b444..6dc27afb8527
> > 100644 --- a/drivers/powercap/intel_rapl.c
> > +++ b/drivers/powercap/intel_rapl.c
> > @@ -887,7 +887,9 @@ static int rapl_write_data_raw(struct
> > rapl_domain *rd, 
> >  	cpu = rd->rp->lead_cpu;
> >  	bits = rapl_unit_xlate(rd, rp->unit, value, 1);
> > -	bits |= bits << rp->shift;
> > +	bits <<= rp->shift;
> > +	bits &= rp->mask;
> > +
> >  	memset(&ma, 0, sizeof(ma));
> >  
> >  	ma.msr_no = rd->msrs[rp->id];
> >   
> 

[Jacob Pan]
diff mbox

Patch

diff --git a/drivers/powercap/intel_rapl.c b/drivers/powercap/intel_rapl.c
index 3c71f608b444..6dc27afb8527 100644
--- a/drivers/powercap/intel_rapl.c
+++ b/drivers/powercap/intel_rapl.c
@@ -887,7 +887,9 @@  static int rapl_write_data_raw(struct rapl_domain *rd,
 
 	cpu = rd->rp->lead_cpu;
 	bits = rapl_unit_xlate(rd, rp->unit, value, 1);
-	bits |= bits << rp->shift;
+	bits <<= rp->shift;
+	bits &= rp->mask;
+
 	memset(&ma, 0, sizeof(ma));
 
 	ma.msr_no = rd->msrs[rp->id];