Re: [Intel-gfx] [PATCH 2/2] drm/i915/uc: Fix undefined behavior due to shift overflowing the constant

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 18.05.2022 13:33, Jani Nikula wrote:
> From: Borislav Petkov <bp@suse.de>
> 
> Fix:
> 
>   In file included from <command-line>:0:0:
>   drivers/gpu/drm/i915/gt/uc/intel_guc.c: In function ‘intel_guc_send_mmio’:
>   ././include/linux/compiler_types.h:352:38: error: call to ‘__compiletime_assert_1047’ \
>   declared with attribute error: FIELD_PREP: mask is not constant
>     _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
> 
> and other build errors due to shift overflowing values.
> 
> See https://lore.kernel.org/r/YkwQ6%2BtIH8GQpuct@zn.tnic for the gory
> details as to why it triggers with older gccs only.
> 
> v2 by Jani:
> - Drop the i915_reg.h changes
> 
> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Ruiqi GONG <gongruiqi1@huawei.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h           | 2 +-
>  drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h | 2 +-
>  drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h          | 2 +-
>  drivers/gpu/drm/i915/gt/uc/intel_guc_reg.h                 | 2 +-
>  4 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> index be9ac47fa9d0..4ef9990ed7f8 100644
> --- a/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> +++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_actions_abi.h
> @@ -50,7 +50,7 @@
>  
>  #define HOST2GUC_SELF_CFG_REQUEST_MSG_LEN		(GUC_HXG_REQUEST_MSG_MIN_LEN + 3u)
>  #define HOST2GUC_SELF_CFG_REQUEST_MSG_0_MBZ		GUC_HXG_REQUEST_MSG_0_DATA0
> -#define HOST2GUC_SELF_CFG_REQUEST_MSG_1_KLV_KEY		(0xffff << 16)
> +#define HOST2GUC_SELF_CFG_REQUEST_MSG_1_KLV_KEY		(0xffffU << 16)

nit: maybe for consistency we should update all these hex constants to
be explicitly marked as "unsigned" (as that was the intention) and also
maybe we should use lowercase "u" - but both that can be done later,

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>

>  #define HOST2GUC_SELF_CFG_REQUEST_MSG_1_KLV_LEN		(0xffff << 0)
>  #define HOST2GUC_SELF_CFG_REQUEST_MSG_2_VALUE32		GUC_HXG_REQUEST_MSG_n_DATAn
>  #define HOST2GUC_SELF_CFG_REQUEST_MSG_3_VALUE64		GUC_HXG_REQUEST_MSG_n_DATAn
> diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
> index c9086a600bce..df83c1cc7c7a 100644
> --- a/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
> +++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h
> @@ -82,7 +82,7 @@ static_assert(sizeof(struct guc_ct_buffer_desc) == 64);
>  #define GUC_CTB_HDR_LEN				1u
>  #define GUC_CTB_MSG_MIN_LEN			GUC_CTB_HDR_LEN
>  #define GUC_CTB_MSG_MAX_LEN			256u
> -#define GUC_CTB_MSG_0_FENCE			(0xffff << 16)
> +#define GUC_CTB_MSG_0_FENCE			(0xffffU << 16)
>  #define GUC_CTB_MSG_0_FORMAT			(0xf << 12)
>  #define   GUC_CTB_FORMAT_HXG			0u
>  #define GUC_CTB_MSG_0_RESERVED			(0xf << 8)
> diff --git a/drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h b/drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h
> index 29ac823acd4c..7d5ba4d97d70 100644
> --- a/drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h
> +++ b/drivers/gpu/drm/i915/gt/uc/abi/guc_messages_abi.h
> @@ -40,7 +40,7 @@
>   */
>  
>  #define GUC_HXG_MSG_MIN_LEN			1u
> -#define GUC_HXG_MSG_0_ORIGIN			(0x1 << 31)
> +#define GUC_HXG_MSG_0_ORIGIN			(0x1U << 31)
>  #define   GUC_HXG_ORIGIN_HOST			0u
>  #define   GUC_HXG_ORIGIN_GUC			1u
>  #define GUC_HXG_MSG_0_TYPE			(0x7 << 28)
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_reg.h b/drivers/gpu/drm/i915/gt/uc/intel_guc_reg.h
> index 2516705b9f36..8dc063f087eb 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_reg.h
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_reg.h
> @@ -28,7 +28,7 @@
>  #define   GS_MIA_HALT_REQUESTED		  (0x02 << GS_MIA_SHIFT)
>  #define   GS_MIA_ISR_ENTRY		  (0x04 << GS_MIA_SHIFT)
>  #define   GS_AUTH_STATUS_SHIFT		30
> -#define   GS_AUTH_STATUS_MASK		  (0x03 << GS_AUTH_STATUS_SHIFT)
> +#define   GS_AUTH_STATUS_MASK		  (0x03U << GS_AUTH_STATUS_SHIFT)
>  #define   GS_AUTH_STATUS_BAD		  (0x01 << GS_AUTH_STATUS_SHIFT)
>  #define   GS_AUTH_STATUS_GOOD		  (0x02 << GS_AUTH_STATUS_SHIFT)
>