Re: [PATCH 43/48] objtool: Add insn_sym() helper

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Apr 22, 2026 at 09:04:11PM -0700, Josh Poimboeuf wrote:
> Alternative replacement instructions awkwardly have insn->sym set to the
> function they get patched to rather than the symbol (or rather lack
> thereof) they belong to in the file.
> 
> This makes it difficult to know where a given instruction actually
> lives.
> 
> Add a new insn_sym() helper which preserves the existing semantic of
> insn->sym.  Rename insn->sym to insn->_sym, which contains the actual
> ELF binary symbol (or NULL, for alternative replacements) an instruction
> lives in.
> 
> The private insn->_sym value will be needed for a subsequent patch.
> 

> +/*
> + * Return the symbol associated with an instruction.  For alternative
> + * replacements, return the symbol of the original code being replaced rather
> + * than NULL.  insn->_sym reflects the actual location in the ELF file.
> + */
> +static inline struct symbol *insn_sym(struct instruction *insn)
> +{
> +	struct symbol *sym = insn->_sym;
> +
> +	if (!sym && insn->alt_group && insn->alt_group->orig_group)
> +		sym = insn->alt_group->orig_group->first_insn->_sym;
> +
> +	return sym;
> +}

That is a bit of a deref fest -- this does not affect performance
negatively?