[PATCH] drm/amdkfd: Fix the shift-out-of-bounds warning

[Ma, Jun]

Hi Felix,

On 1/10/2024 11:57 PM, Felix Kuehling wrote:
> On 2024-01-10 04:39, Ma Jun wrote:
>> There is following shift-out-of-bounds warning if ecode=0.
>> "shift exponent 4294967295 is too large for 64-bit type 'long long unsigned int'"
>>
>> Signed-off-by: Ma Jun <Jun.Ma2 at amd.com>
>> ---
>>   include/uapi/linux/kfd_ioctl.h | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/uapi/linux/kfd_ioctl.h b/include/uapi/linux/kfd_ioctl.h
>> index 2aa88afe305b..129325b02a91 100644
>> --- a/include/uapi/linux/kfd_ioctl.h
>> +++ b/include/uapi/linux/kfd_ioctl.h
>> @@ -1004,7 +1004,7 @@ enum kfd_dbg_trap_exception_code {
>>   };
>>   
>>   /* Mask generated by ecode in kfd_dbg_trap_exception_code */
>> -#define KFD_EC_MASK(ecode)	(1ULL << (ecode - 1))
>> +#define KFD_EC_MASK(ecode)	(BIT(ecode) - 1)
> 
> This is not the same thing. We want a bit mask with one bit set. And 
> ecode=1 should set bit 0. ecode=0 is not a valid code and doesn't have a 
> valid mask. You could use BIT((ecode) - 1), but I think that would give 
> you the same warning for ecode=0. I also don't see BIT defined anywhere 
> under include/uapi, so I think using this in the API header would break 
> the build in user mode.
> 
> Where are you seeing the warning about the bad shift exponent? Looks 
> like someone is using the KFD_EC_MASK macro incorrectly. Or if there is 
> a legitimate use of it with ecode=0, then the correct fix would be
> 
This warning is caused by following code in function event_interrupt_wq_v10()
		
else if (source_id == SOC15_INTSRC_CP_BAD_OPCODE) {
	kfd_set_dbg_ev_from_interrupt(dev, pasid,
	KFD_DEBUG_DOORBELL_ID(context_id0),
	KFD_EC_MASK(KFD_DEBUG_CP_BAD_OP_ECODE(context_id0)),
	NULL,
	0);
}


> #define KFD_EC_MASK(ecode)	((ecode) ? 1ULL << (ecode - 1) : 0ULL)

This can fix the warning.

Regards
Ma Jun
> 
> Regards,
>    Felix
> 
> 
>>   
>>   /* Masks for exception code type checks below */
>>   #define KFD_EC_MASK_QUEUE	(KFD_EC_MASK(EC_QUEUE_WAVE_ABORT) |	\