Re: [PATCH] [RFC V1]s390/perf: fix 'start' address of module's map

[Songshan Gong]

å 7/8/2016 11:21 PM, Jiri Olsa åé:
> On Thu, Jul 07, 2016 at 09:49:36AM +0800, Song Shan Gong wrote:
>
> SNIP
>
> > +	char *line = NULL;
> > +	size_t n;
> > +	char *sep;
> > +
> > +	module_name[len - 1] = '\0';
> > +	module_name += 1;
> > +	snprintf(path, PATH_MAX, "%s/sys/module/%s/sections/.text",
> > +				machine->root_dir, module_name);
> > +	file = fopen(path, "r");
> > +	if (file == NULL)
> > +		return -1;
> > +
> > +	len = getline(&line, &n, file);
> > +	if (len < 0) {
> > +		err = -1;
> > +		goto out;
> > +	}
> > +	line[--len] = '\0'; /* \n */
> > +	sep = strrchr(line, 'x');
> > +	if (sep == NULL) {
> > +		err = -1;
> > +		goto out;
> > +	}
> > +	hex2u64(sep + 1, &text_start);
>
> we have following functions in tools/lib/api/fs to read
> single number from file, which I assume you do above:
>
> int sysfs__read_int(const char *entry, int *value);
> int sysfs__read_ull(const char *entry, unsigned long long *value);
>
> please check if you could use some of them,
> we could add some more generic one if needed

It seems infeasible.
Each value in /sys/module/[module name]/sections/.text is a string like 
"0x000003ff8130078\n".
But the core function 'strtoull(line, NULL, 10)' in sysfs__read_ull is 
based on decimal.

Maybe you can introduce a new argument indicating the value is based on 
hex or decimal, or binary?

> thanks,
> jirka

--
SongShan Gong