On Tue, 04 May 2021, Andi Kleen ak@linux.intel.com wrote:
From: Andi Kleen andi@firstfloor.org
Newer gcc prints the following warning:
drivers/gpu/drm/i915/intel_pm.c:3057:9: warning: ‘intel_print_wm_latency’ reading 16 bytes from a region of size 10 [-Wstringop-overread] and some other related warnings in similar functions.
gcc has a point here. Some of the latency arrays only have 5 members, but print_wm_latency may read up to max_level returned by ilk_wm_max_level, which can be upto 7 for the >= GEN9 case.
So it will read some fields beyond the array.
Increase all the latency fields to 8 members, which is enough for SKL.
I don't know if they are correctly initialized upto 8, but dev_priv should start out as zero, so presumably they will be zero.
Thanks, the warning should be fixed by commit
c6deb5e97ded ("drm/i915/pm: Make the wm parameter of print_wm_latency a pointer")
in drm-intel-next.
There doesn't actually seem to be a bug here, but I wonder if we should send that to stable or v5.13-rc1+ anyway to stop people spending time on the same issue.
BR, Jani.
Signed-off-by: Andi Kleen andi@firstfloor.org
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 cb62ddba2035..c80add5f6d33 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];
u16 spr_latency[5];
u16 spr_latency[8];
u16 cur_latency[5];
u16 cur_latency[8];
- Raw watermark memory latency values
- for SKL for all 8 levels