Re: [PATCH 12/18] tracing: Add accessing direct address from function based events

Masami Hiramatsu
2018-02-12T15:47:50Z

On Mon, 12 Feb 2018 11:06:44 +0900
Namhyung Kim <namhyung@kernel.org> wrote:

> Hi Steve,
>
> On Fri, Feb 09, 2018 at 05:07:37PM -0500, Steven Rostedt wrote:
> > On Fri, 9 Feb 2018 09:34:36 +0900
> > Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > > Couldn't we use the symbol name directly? Maybe it needs a syntax to
> > > indicate global variable. Like this?
> > >
> > > # echo 'do_IRQ(int $total_forks)' > function_events
> >
> >
> > I decided to stick with "$".
>
> Good.
>
>
> [SNIP]
> > static enum func_states
> > process_event(struct func_event *fevent, const char *token, enum func_states state)
> > {
> > @@ -469,6 +479,8 @@ process_event(struct func_event *fevent, const char *token, enum func_states sta
> > case FUNC_STATE_ARRAY_END:
> > if (WARN_ON(!fevent->last_arg))
> > break;
> > + if (token[0] == '$')
> > + return FUNC_STATE_SYMBOL;
> > if (update_arg_name(fevent, token) < 0)
> > break;
> > if (strncmp(token, "0x", 2) == 0)
> > @@ -542,6 +554,11 @@ process_event(struct func_event *fevent, const char *token, enum func_states sta
> > fevent->last_arg->index += val;
> > return FUNC_STATE_VAR;
> >
> > + case FUNC_STATE_SYMBOL:
> > + if (!isalpha(token[0]) && token[0] != '_')
> > + break;
> > + goto equal;
> > +
> > case FUNC_STATE_ADDR:
> > switch (token[0]) {
> > case ')':
> > @@ -599,14 +616,26 @@ process_event(struct func_event *fevent, const char *token, enum func_states sta
> > break;
> >
> > case FUNC_STATE_EQUAL:
> > + if (token[0] == '$')
> > + return FUNC_STATE_SYMBOL;
> > if (strncmp(token, "0x", 2) != 0)
> > break;
> > equal:
> > if (WARN_ON(!fevent->last_arg))
> > break;
> > - ret = kstrtoul(token, 0, &val);
> > - if (ret < 0)
> > - break;
> > + if (isalpha(token[0]) || token[0] != '_') {
>
> I guess you wanted the token[0] being '_'. Maybe it'd be better adding
>
> #define isident0(x) (isalpha(x) || (x) == '_')

If this '$' is only for the symbol or direct address(with 0x prefix),
you just need to check by !isdigit(token[0]), isn't it?
(and if it is insane get_symbol just fails)

Thanks,

>
> ?
>
> Thanks,
> Namhyung
>
>
> > + ret = get_symbol(token, &val);
> > + if (ret < 0)
> > + break;
> > + if (!fevent->last_arg->name) {
> > + if (update_arg_name(fevent, token) < 0)
> > + break;
> > + }
> > + } else {
> > + ret = kstrtoul(token, 0, &val);
> > + if (ret < 0)
> > + break;
> > + }
> > update_arg = false;
> > fevent->last_arg->index = val;
> > fevent->last_arg->arg = -1;
> > --
> > 2.13.6
> >

--
Masami Hiramatsu <mhiramat@kernel.org>