Re: [PATCH] [PATCH] powerpc/sstep: Check ISA 3.0 instruction validity before emulation

[Ananth N Mavinakayanahalli <ananth@linux.ibm.com>]

On 1/20/21 3:44 PM, Naveen N. Rao wrote:
> On 2021/01/20 03:16PM, Ananth N Mavinakayanahalli wrote:
...

>> diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
>> index bf7a7d62ae8b..ed119858e5e9 100644
>> --- a/arch/powerpc/lib/sstep.c
>> +++ b/arch/powerpc/lib/sstep.c
>> @@ -1528,6 +1528,8 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs,
>>   		goto compute_done;
>>   
>>   	case 19:
>> +		if (!cpu_has_feature(CPU_FTR_ARCH_300))
>> +			return -1;
>>   		if (((word >> 1) & 0x1f) == 2) {
>>   			/* addpcis */
>>   			imm = (short) (word & 0xffc1);	/* d0 + d2 fields */
> 
> The cpu feature check should be within the if condition above since
> there are other instructions under opcode 19. This is not an issue right
> now as we don't emulate any of the others after this point, but it would
> be good to restrict the change to specific instructions.
> 
> Rest of the changes below look good to me. The only other v3.0
> instruction we need to gate is the 'scv' instruction. It would be good
> to handle that too.

I missed this in v2.. will send a v3. There is a bigger change needed to
accommodate scv since we currently don't check for it in analyze_insn().

-- 
Ananth