On Thu, 18 Jun 2020, Matt Helsley wrote:
> Rather than a standalone executable merge recordmcount as a sub command
> of objtool. This is a small step towards cleaning up recordmcount and
> eventually sharing ELF code with objtool.
>
> For the initial step all that's required is a bit of Makefile changes
> and invoking the former main() function from recordmcount.c because the
> subcommand code uses similar function arguments as main when dispatching.
>
> objtool ignores some object files that tracing does not, specifically
> those with OBJECT_FILES_NON_STANDARD Makefile variables. For this reason
> we keep the recordmcount_dep separate from the objtool_dep. When using
> objtool mcount we can also, like the other objtool invocations, just
> depend on the binary rather than the source the binary is built from.
>
> Subsequent patches will gradually convert recordmcount to use
> more and more of libelf/objtool's ELF accessor code. This will both
> clean up recordmcount to be more easily readable and remove
> recordmcount's crude accessor wrapping code.
I'll try to leave only relevant parts for a question below...
> sub_cmd_record_mcount = \
> if [ $(@) != "scripts/mod/empty.o" ]; then \
> - $(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS)
> "$(@)"; \
> + $(objtree)/tools/objtool/objtool mcount record
> $(RECORDMCOUNT_FLAGS) "$(@)"; \
> fi;
> +int cmd_mcount(int argc, const char **argv)
> +{
> + argc--; argv++;
> + if (argc <= 0)
> + usage_with_options(mcount_usage, mcount_options);
> +
> + if (!strncmp(argv[0], "record", 6)) {
> + argc = parse_options(argc, argv,
> + mcount_options, mcount_usage, 0);
> + if (argc < 1)
> + usage_with_options(mcount_usage, mcount_options);
> +
> + return record_mcount(argc, argv);
> + }
> +
> + usage_with_options(mcount_usage, mcount_options);
> +
> + return 0;
> +}
> -int main(int argc, char *argv[])
> +int record_mcount(int argc, const char **argv)
> {
> const char ftrace[] = "/ftrace.o";
> int ftrace_size = sizeof(ftrace) - 1;
> int n_error = 0; /* gcc-4.3.0 false positive complaint */
> - int c;
> int i;
>
> - while ((c = getopt(argc, argv, "w")) >= 0) {
> - switch (c) {
> - case 'w':
> - warn_on_notrace_sect = 1;
> - break;
> - default:
> - fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
> - return 0;
> - }
> - }
> -
> - if ((argc - optind) < 1) {
> - fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
> - return 0;
> - }
> -
> /* Process each file in turn, allowing deep failure. */
> - for (i = optind; i < argc; i++) {
> - char *file = argv[i];
> + for (i = 0; i < argc; i++) {
> + const char *file = argv[i];
> int len;
Do you expect that mcount subcmd would be called on more than one object
file at a time? I don't see a reason for that with all the Makefile
changes, but I may be missing something (Kbuild is a maze for me).
Because if not, I think it would be nice to make record_mcount() more
similar to what we have for check(). After Julien's changes
(20200608071203.4055-1-jthie...@redhat.com) at least. So that
record_mcount() could accept struct objtool_file and work directly on
that.
It would also impact several other patches in the series. For example,
is there a need for a private 'struct elf *lf' in mcount.c?
Thanks
Miroslav
