Re: [PATCH 10/11] drm/i915: avoid stringop-overread warning on pri_latency
From: Jani Nikula <jani.nikula@linux.intel.com>
Date: 2021-03-24 15:31:33
Also in:
ath11k, dri-devel, intel-gfx, linux-arm-kernel, linux-scsi, linux-security-module, linux-wireless, lkml, netdev
On Mon, 22 Mar 2021, Arnd Bergmann [off-list ref] wrote:
From: Arnd Bergmann <arnd@arndb.de>
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 <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- 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 _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx