Re: [PATCH v3 4/4] objtool: orc_gen: Move orc_entry out of instruction structure

[peterz@infradead.org]

On Thu, Jul 30, 2020 at 10:41:43AM +0100, Julien Thierry wrote:
> One orc_entry is associated with each instruction in the object file,
> but having the orc_entry contained by the instruction structure forces
> architectures not implementing the orc subcommands to provide a dummy
> definition of the orc_entry.
> 
> Avoid that by having orc_entries in a separate list, part of the
> objtool_file.
> 

> diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
> index 66fd56c33303..00f1efd05653 100644
> --- a/tools/objtool/orc_gen.c
> +++ b/tools/objtool/orc_gen.c
> @@ -9,18 +9,33 @@
>  #include "check.h"
>  #include "warn.h"
>  
> +struct orc_data {
> +	struct list_head list;
> +	struct instruction *insn;
> +	struct orc_entry orc;
> +};
> +
>  int create_orc(struct objtool_file *file)
>  {
>  	struct instruction *insn;
>  
>  	for_each_insn(file, insn) {
> -		struct orc_entry *orc = &insn->orc;
>  		struct cfi_reg *cfa = &insn->cfi.cfa;
>  		struct cfi_reg *bp = &insn->cfi.regs[CFI_BP];
> +		struct orc_entry *orc;
> +		struct orc_data *od;
>  
>  		if (!insn->sec->text)
>  			continue;
>  
> +		od = calloc(1, sizeof(*od));
> +		if (!od)
> +			return -1;
> +		od->insn = insn;
> +		list_add_tail(&od->list, &file->orc_data_list);
> +
> +		orc = &od->orc;
> +
>  		orc->end = insn->cfi.end;
>  
>  		if (cfa->base == CFI_UNDEFINED) {

This will dramatically increase the amount of allocation calls, what, if
anything, does this do for the performance of objtool?