linux-kernel - Re: [PATCH v5 1/2] perf sdt: add scanning of sdt probles arguments

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Message-ID: <20170321135257.GB30938@kernel.org>
Date:   Tue, 21 Mar 2017 10:52:57 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Alexis Berlemont <alexis.berlemont@...il.com>,
        linux-kernel@...r.kernel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com
Subject: Re: [PATCH v5 1/2] perf sdt: add scanning of sdt probles arguments

Em Mon, Mar 06, 2017 at 02:39:15PM +0100, Masami Hiramatsu escreveu:
> On Wed, 14 Dec 2016 01:07:31 +0100
> Alexis Berlemont <alexis.berlemont@...il.com> wrote:
> 
> > During a "perf buildid-cache --add" command, the section
> > ".note.stapsdt" of the "added" binary is scanned in order to list the
> > available SDT markers available in a binary. The parts containing the
> > probes arguments were left unscanned.
> > 
> > The whole section is now parsed; the probe arguments are extracted for
> > later use.
> > 
> 
> Looks good to me.
> 
> Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks, applied.
 
> Thanks!
> 
> > Signed-off-by: Alexis Berlemont <alexis.berlemont@...il.com>
> > ---
> >  tools/perf/util/symbol-elf.c | 25 +++++++++++++++++++++++--
> >  tools/perf/util/symbol.h     |  1 +
> >  2 files changed, 24 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
> > index 99400b0..7725c3f 100644
> > --- a/tools/perf/util/symbol-elf.c
> > +++ b/tools/perf/util/symbol-elf.c
> > @@ -1822,7 +1822,7 @@ void kcore_extract__delete(struct kcore_extract *kce)
> >  static int populate_sdt_note(Elf **elf, const char *data, size_t len,
> >  			     struct list_head *sdt_notes)
> >  {
> > -	const char *provider, *name;
> > +	const char *provider, *name, *args;
> >  	struct sdt_note *tmp = NULL;
> >  	GElf_Ehdr ehdr;
> >  	GElf_Addr base_off = 0;
> > @@ -1881,6 +1881,25 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
> >  		goto out_free_prov;
> >  	}
> >  
> > +	args = memchr(name, '\0', data + len - name);
> > +
> > +	/*
> > +	 * There is no argument if:
> > +	 * - We reached the end of the note;
> > +	 * - There is not enough room to hold a potential string;
> > +	 * - The argument string is empty or just contains ':'.
> > +	 */
> > +	if (args == NULL || data + len - args < 2 ||
> > +		args[1] == ':' || args[1] == '\0')
> > +		tmp->args = NULL;
> > +	else {
> > +		tmp->args = strdup(++args);
> > +		if (!tmp->args) {
> > +			ret = -ENOMEM;
> > +			goto out_free_name;
> > +		}
> > +	}
> > +
> >  	if (gelf_getclass(*elf) == ELFCLASS32) {
> >  		memcpy(&tmp->addr, &buf, 3 * sizeof(Elf32_Addr));
> >  		tmp->bit32 = true;
> > @@ -1892,7 +1911,7 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
> >  	if (!gelf_getehdr(*elf, &ehdr)) {
> >  		pr_debug("%s : cannot get elf header.\n", __func__);
> >  		ret = -EBADF;
> > -		goto out_free_name;
> > +		goto out_free_args;
> >  	}
> >  
> >  	/* Adjust the prelink effect :
> > @@ -1917,6 +1936,8 @@ static int populate_sdt_note(Elf **elf, const char *data, size_t len,
> >  	list_add_tail(&tmp->note_list, sdt_notes);
> >  	return 0;
> >  
> > +out_free_args:
> > +	free(tmp->args);
> >  out_free_name:
> >  	free(tmp->name);
> >  out_free_prov:
> > diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
> > index 6c358b7..9222c7e 100644
> > --- a/tools/perf/util/symbol.h
> > +++ b/tools/perf/util/symbol.h
> > @@ -351,6 +351,7 @@ int arch__choose_best_symbol(struct symbol *syma, struct symbol *symb);
> >  struct sdt_note {
> >  	char *name;			/* name of the note*/
> >  	char *provider;			/* provider name */
> > +	char *args;
> >  	bool bit32;			/* whether the location is 32 bits? */
> >  	union {				/* location, base and semaphore addrs */
> >  		Elf64_Addr a64[3];
> > -- 
> > 2.10.2
> > 
> 
> 
> -- 
> Masami Hiramatsu <mhiramat@...nel.org>