On 11/22/23 14:13, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> gcc prints a warning about a possible array overflow for a couple of
> callers of dp_decide_lane_settings() after commit 1b56c90018f0 ("Makefile:
> Enable -Wstringop-overflow globally"):
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c: In function 'dp_perform_fixed_vs_pe_training_sequence_legacy':
> drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c:426:25: error: 'dp_decide_lane_settings' accessing 4 bytes in a region of size 1 [-Werror=stringop-overflow=]
> 426 | dp_decide_lane_settings(lt_settings, dpcd_lane_adjust,
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 427 | lt_settings->hw_lane_settings, lt_settings->dpcd_lane_settings);
> | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/../display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c:426:25: note: referencing argument 4 of type 'union dpcd_training_lane[4]'
>
> I'm not entirely sure what caused this, but changing the prototype to expect
> a pointer instead of an array avoids the warnings.
>
> Fixes: 7727e7b60f82 ("drm/amd/display: Improve robustness of FIXED_VS link training at DP1 rates")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Acked-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> # build-tested
Thanks.
> ---
> .../gpu/drm/amd/display/dc/link/protocols/link_dp_training.c | 2 +-
> .../gpu/drm/amd/display/dc/link/protocols/link_dp_training.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c
> index 90339c2dfd84..5a0b04518956 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c
> +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c
> @@ -807,7 +807,7 @@ void dp_decide_lane_settings(
> const struct link_training_settings *lt_settings,
> const union lane_adjust ln_adjust[LANE_COUNT_DP_MAX],
> struct dc_lane_settings hw_lane_settings[LANE_COUNT_DP_MAX],
> - union dpcd_training_lane dpcd_lane_settings[LANE_COUNT_DP_MAX])
> + union dpcd_training_lane *dpcd_lane_settings)
> {
> uint32_t lane;
>
> diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.h b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.h
> index 7d027bac8255..851bd17317a0 100644
> --- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.h
> +++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.h
> @@ -111,7 +111,7 @@ void dp_decide_lane_settings(
> const struct link_training_settings *lt_settings,
> const union lane_adjust ln_adjust[LANE_COUNT_DP_MAX],
> struct dc_lane_settings hw_lane_settings[LANE_COUNT_DP_MAX],
> - union dpcd_training_lane dpcd_lane_settings[LANE_COUNT_DP_MAX]);
> + union dpcd_training_lane *dpcd_lane_settings);
>
> enum dc_dp_training_pattern decide_cr_training_pattern(
> const struct dc_link_settings *link_settings);
--
#Randy
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