Re: [PATCH v2 10/10] objtool: Support multiple stack_op per instruction

[Julien Thierry]

On 4/2/20 6:54 PM, Josh Poimboeuf wrote:
> On Fri, Mar 27, 2020 at 03:28:47PM +0000, Julien Thierry wrote:
> > @@ -127,6 +129,10 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
> >   	if (insn.sib.nbytes)
> >   		sib = insn.sib.bytes[0];
> >   
> > +	op = calloc(1, sizeof(*op));
> > +	if (!op)
> > +		return -1;
> > +
>
> Why not malloc()?

It's just that previsously, stack_op was part of the instruction 
structure and was initialized to all 0 in decode_instructions(). Now 
that it's created here, I assumed it would be better to have the same 
thing here and initialized the new stack_op to all 0.

Do you prefer to have an explicit malloc() + memset()?

> > +static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
> > +{
> > +	struct stack_op *op;
> > +
> > +	list_for_each_entry(op, &insn->stack_ops, list) {
> > +		int res;
> > +
> > +		res = update_insn_state(insn, state, op);
> > +		if (res)
> > +			return res;
>
> This should probably be like:
>
> 		if (update_insn_state(insn, state, op))
> 			return 1;
>
> That way the error codes are converted to non-fatal warnings like before
> (which I admit is confusing...)

Right, I'll change this.

> > @@ -2205,29 +2244,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
> >   			return 0;
> >   
> >   		case INSN_STACK:
> > -			if (update_insn_state(insn, &state))
> > +			if (handle_insn_ops(insn, &state))
> >   				return 1;
>
> How about "handle_stack_ops"?

Works for me!

Thanks,

--
Julien Thierry