Re: [PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency
On Wed, Mar 24, 2021 at 05:30:24PM +0200, Jani Nikula wrote:
> On Mon, 22 Mar 2021, Arnd Bergmann wrote:
> > From: Arnd Bergmann
> >
> > gcc-11 warns about what appears to be an out-of-range array access:
> >
> > In function ‘snb_wm_latency_quirk’,
> > inlined from ‘ilk_setup_wm_latency’ at
> > drivers/gpu/drm/i915/intel_pm.c:3108:3:
> > drivers/gpu/drm/i915/intel_pm.c:3057:9: error: ‘intel_print_wm_latency’
> > reading 16 bytes from a region of size 10 [-Werror=stringop-overread]
> > 3057 | intel_print_wm_latency(dev_priv, "Primary",
> > dev_priv->wm.pri_latency);
> > |
> > ^
> > drivers/gpu/drm/i915/intel_pm.c: In function ‘ilk_setup_wm_latency’:
> > drivers/gpu/drm/i915/intel_pm.c:3057:9: note: referencing argument 3 of
> > type ‘const u16 *’ {aka ‘const short unsigned int *’}
> > drivers/gpu/drm/i915/intel_pm.c:2994:13: note: in a call to function
> > ‘intel_print_wm_latency’
> > 2994 | static void intel_print_wm_latency(struct drm_i915_private
> > *dev_priv,
> > | ^~
> >
> > My guess is that this code is actually safe because the size of the
> > array depends on the hardware generation, and the function checks for
> > that, but at the same time I would not expect the compiler to work it
> > out correctly, and the code seems a little fragile with regards to
> > future changes. Simply increasing the size of the array should help.
>
> Agreed, I don't think there's an issue, but the code could use a bunch
> of improvements.
>
> Like, we have intel_print_wm_latency() for debug logging and
> wm_latency_show() for debugfs, and there's a bunch of duplication and
> ugh.
There is all this ancient stuff in review limbo...
https://patchwork.freedesktop.org/series/50802/
--
Ville Syrjälä
Intel
___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: [PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency
On Mon, 22 Mar 2021, Arnd Bergmann wrote:
> From: Arnd Bergmann
>
> gcc-11 warns about what appears to be an out-of-range array access:
>
> In function ‘snb_wm_latency_quirk’,
> inlined from ‘ilk_setup_wm_latency’ at
> drivers/gpu/drm/i915/intel_pm.c:3108:3:
> drivers/gpu/drm/i915/intel_pm.c:3057:9: error: ‘intel_print_wm_latency’
> reading 16 bytes from a region of size 10 [-Werror=stringop-overread]
> 3057 | intel_print_wm_latency(dev_priv, "Primary",
> dev_priv->wm.pri_latency);
> |
> ^
> drivers/gpu/drm/i915/intel_pm.c: In function ‘ilk_setup_wm_latency’:
> drivers/gpu/drm/i915/intel_pm.c:3057:9: note: referencing argument 3 of type
> ‘const u16 *’ {aka ‘const short unsigned int *’}
> drivers/gpu/drm/i915/intel_pm.c:2994:13: note: in a call to function
> ‘intel_print_wm_latency’
> 2994 | static void intel_print_wm_latency(struct drm_i915_private *dev_priv,
> | ^~
>
> My guess is that this code is actually safe because the size of the
> array depends on the hardware generation, and the function checks for
> that, but at the same time I would not expect the compiler to work it
> out correctly, and the code seems a little fragile with regards to
> future changes. Simply increasing the size of the array should help.
Agreed, I don't think there's an issue, but the code could use a bunch
of improvements.
Like, we have intel_print_wm_latency() for debug logging and
wm_latency_show() for debugfs, and there's a bunch of duplication and
ugh.
But this seems like the easiest fix for the warning.
Reviewed-by: Jani Nikula
> Signed-off-by: Arnd Bergmann
> ---
> drivers/gpu/drm/i915/i915_drv.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 26d69d06aa6d..3567602e0a35 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1095,11 +1095,11 @@ struct drm_i915_private {
>* in 0.5us units for WM1+.
>*/
> /* primary */
> - u16 pri_latency[5];
> + u16 pri_latency[8];
> /* sprite */
> - u16 spr_latency[5];
> + u16 spr_latency[8];
> /* cursor */
> - u16 cur_latency[5];
> + u16 cur_latency[8];
> /*
>* Raw watermark memory latency values
>* for SKL for all 8 levels
--
Jani Nikula, Intel Open Source Graphics Center
___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
[PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency
From: Arnd Bergmann
gcc-11 warns about what appears to be an out-of-range array access:
In function ‘snb_wm_latency_quirk’,
inlined from ‘ilk_setup_wm_latency’ at
drivers/gpu/drm/i915/intel_pm.c:3108:3:
drivers/gpu/drm/i915/intel_pm.c:3057:9: error: ‘intel_print_wm_latency’ reading
16 bytes from a region of size 10 [-Werror=stringop-overread]
3057 | intel_print_wm_latency(dev_priv, "Primary",
dev_priv->wm.pri_latency);
|
^
drivers/gpu/drm/i915/intel_pm.c: In function ‘ilk_setup_wm_latency’:
drivers/gpu/drm/i915/intel_pm.c:3057:9: note: referencing argument 3 of type
‘const u16 *’ {aka ‘const short unsigned int *’}
drivers/gpu/drm/i915/intel_pm.c:2994:13: note: in a call to function
‘intel_print_wm_latency’
2994 | static void intel_print_wm_latency(struct drm_i915_private *dev_priv,
| ^~
My guess is that this code is actually safe because the size of the
array depends on the hardware generation, and the function checks for
that, but at the same time I would not expect the compiler to work it
out correctly, and the code seems a little fragile with regards to
future changes. Simply increasing the size of the array should help.
Signed-off-by: Arnd Bergmann
---
drivers/gpu/drm/i915/i915_drv.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 26d69d06aa6d..3567602e0a35 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1095,11 +1095,11 @@ struct drm_i915_private {
* in 0.5us units for WM1+.
*/
/* primary */
- u16 pri_latency[5];
+ u16 pri_latency[8];
/* sprite */
- u16 spr_latency[5];
+ u16 spr_latency[8];
/* cursor */
- u16 cur_latency[5];
+ u16 cur_latency[8];
/*
* Raw watermark memory latency values
* for SKL for all 8 levels
--
2.29.2
___
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
