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Message-ID: <20120109112236.GA10189@linux.vnet.ibm.com>
Date: Mon, 9 Jan 2012 16:52:36 +0530
From: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Oleg Nesterov <oleg@...hat.com>, Ingo Molnar <mingo@...e.hu>,
Andrew Morton <akpm@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Linux-mm <linux-mm@...ck.org>, Andi Kleen <andi@...stfloor.org>,
Christoph Hellwig <hch@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Roland McGrath <roland@...k.frob.com>,
Thomas Gleixner <tglx@...utronix.de>,
Arnaldo Carvalho de Melo <acme@...radead.org>,
Anton Arapov <anton@...hat.com>,
Ananth N Mavinakayanahalli <ananth@...ibm.com>,
Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
yrl.pp-manager.tt@...achi.com
Subject: Re: [PATCH v8 3.2.0-rc5 9/9] perf: perf interface for uprobes
> >
> > +static int init_perf_uprobes(void)
>
> This would be better called as init_user_exec().
okay
> > +{
> > + int ret = 0;
> > +
> > + symbol_conf.try_vmlinux_path = false;
> > + symbol_conf.sort_by_name = true;
> > + ret = symbol__init();
> > + if (ret < 0)
> > + pr_debug("Failed to init symbol map.\n");
> > +
> > + return ret;
> > +}
>
> and this can be used in show_available_funcs() too.
Okay.
>
> > +
> > +static int convert_to_perf_probe_point(struct probe_trace_point *tp,
> > + struct perf_probe_point *pp)
> > +{
> > + pp->function = strdup(tp->symbol);
> > + if (pp->function == NULL)
> > + return -ENOMEM;
> > + pp->offset = tp->offset;
> > + pp->retprobe = tp->retprobe;
> > +
> > + return 0;
> > +}
>
> This function could be used in kprobe_convert_to_perf_probe() too.
> In that case, it will be separated as a cleanup from this.
Do you mean kprobe_convert_to_perf_probe under #ifdef DWARF_SUPPORT?
because kprobe_convert_to_perf_probe under ifndef DWARF_SUPPORT already
uses convert_to_perf_probe_point.
>
> > #ifdef DWARF_SUPPORT
> > /* Open new debuginfo of given module */
> > static struct debuginfo *open_debuginfo(const char *module)
> > @@ -281,6 +309,15 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
> > struct debuginfo *dinfo = open_debuginfo(target);
>
> You need not to call open_debuginfo() when it is a uprobe.
>
Okay
> > int ntevs, ret = 0;
> >
> > + if (pev->uprobes) {
> > + if (need_dwarf) {
> > + pr_warning("Debuginfo-analysis is not yet supported"
> > + " with -x/--exec option.\n");
> > + return -ENOSYS;
> > + }
> > + return convert_name_to_addr(pev, target);
> > + }
> > +
> > if (!dinfo) {
> > if (need_dwarf) {
> > pr_warning("Failed to open debuginfo file.\n");
> [...]
> > @@ -887,6 +921,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> > return -EINVAL;
> > }
> >
> > + if (pev->uprobes && !pp->function) {
> > + semantic_error("No function specified for uprobes");
> > + return -EINVAL;
> > + }
>
> I think this check would better be done when converting
> function to address.
This can also be done.
>
> > if ((pp->offset || pp->line || pp->lazy_line) && pp->retprobe) {
> > semantic_error("Offset/Line/Lazy pattern can't be used with "
> > "return probe.\n");
> > @@ -896,6 +935,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
> > pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
> > pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
> > pp->lazy_line);
> > +
> > + if (pev->uprobes && perf_probe_event_need_dwarf(pev)) {
> > + semantic_error("no dwarf based probes for uprobes.");
> > + return -EINVAL;
> > + }
>
> Hmm, this also would be done in converting phase.
Okay, will do.
>
> > return 0;
> > }
> >
> > @@ -1047,7 +1091,8 @@ bool perf_probe_event_need_dwarf(struct perf_probe_event *pev)
> > {
> > int i;
> >
> > - if (pev->point.file || pev->point.line || pev->point.lazy_line)
> > + if ((pev->point.file && !pev->uprobes) || pev->point.line ||
> > + pev->point.lazy_line)
>
> point.file will point a source file, not executable file.
>
> > return true;
> >
> > for (i = 0; i < pev->nargs; i++)
> > @@ -1344,11 +1389,17 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
> > if (buf == NULL)
> > return NULL;
> >
> > - len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s%s%s+%lu",
> > - tp->retprobe ? 'r' : 'p',
> > - tev->group, tev->event,
> > - tp->module ?: "", tp->module ? ":" : "",
> > - tp->symbol, tp->offset);
> > + if (tev->uprobes)
> > + len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s",
> > + tp->retprobe ? 'r' : 'p',
> > + tev->group, tev->event, tp->symbol);
> > + else
> > + len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s%s%s+%lu",
> > + tp->retprobe ? 'r' : 'p',
> > + tev->group, tev->event,
> > + tp->module ?: "", tp->module ? ":" : "",
> > + tp->symbol, tp->offset);
>
> I think tp->module should be the executable file even when
> tp is a user space probe, because when parsing the uprobes list
> in tracing/trace_uprobes, exec file will be stored in tp->module.
can be done. What I used to do is overload the tp->symbol with the
real-name as well as the offset. Now I will just keep the offset in the
symbol and use the target that the user has requested.
>
> > +
> > if (len <= 0)
> > goto error;
> >
> [...]
> >
> > -/* Get raw string list of current kprobe_events */
> > +static int open_kprobe_events(bool readwrite)
> > +{
> > + return open_probe_events(readwrite, 1);
> > +}
> > +
> > +static int open_uprobe_events(bool readwrite)
> > +{
> > + return open_probe_events(readwrite, 0);
> > +}
>
> Hmm, I'd rather like to have
> open_probe_events(const char *fname, bool rw)
> and print errors in each open_u/kprobe_events().
>
Okay, I wanted to keep using the errno just after open but I am fine to
split this.
>
> > +
> > +/* Get raw string list of current kprobe_events or uprobe_events */
> > static struct strlist *get_probe_trace_command_rawlist(int fd)
> > {
> > int ret, idx;
> [...]
> > @@ -2065,30 +2180,150 @@ static int filter_available_functions(struct map *map __unused,
> > return 1;
> > }
> >
> > -int show_available_funcs(const char *target, struct strfilter *_filter)
> > +static int __show_available_funcs(struct map *map)
> > +{
> > + if (map__load(map, filter_available_functions)) {
> > + pr_err("Failed to load map.\n");
> > + return -EINVAL;
> > + }
> > + if (!dso__sorted_by_name(map->dso, map->type))
> > + dso__sort_by_name(map->dso, map->type);
> > +
> > + dso__fprintf_symbols_by_name(map->dso, map->type, stdout);
> > + return 0;
> > +}
> > +
> > +static int available_kernel_funcs(const char *module)
> > {
> > struct map *map;
> > int ret;
> >
> > - setup_pager();
> > -
> > ret = init_vmlinux();
> > if (ret < 0)
> > return ret;
> >
> > - map = kernel_get_module_map(target);
> > + map = kernel_get_module_map(module);
> > if (!map) {
> > - pr_err("Failed to find %s map.\n", (target) ? : "kernel");
> > + pr_err("Failed to find %s map.\n", (module) ? : "kernel");
> > return -EINVAL;
> > }
> > + return __show_available_funcs(map);
> > +}
>
> I think we'd better introduce available_user_funcs() here too.
Okay done.
>
> > +
> > +int show_available_funcs(const char *target, struct strfilter *_filter,
> > + bool user)
> > +{
> > + struct map *map;
> > + int ret;
> > +
> > + setup_pager();
> > available_func_filter = _filter;
> > +
> > + if (!user)
> > + return available_kernel_funcs(target);
> > +
> > + symbol_conf.try_vmlinux_path = false;
> > + symbol_conf.sort_by_name = true;
> > + ret = symbol__init();
> > + if (ret < 0) {
> > + pr_err("Failed to init symbol map.\n");
> > + return ret;
> > + }
> > + map = dso__new_map(target);
> > + ret = __show_available_funcs(map);
> > + dso__delete(map->dso);
> > + map__delete(map);
> > + return ret;
> > +}
> > +
> > +#define DEFAULT_FUNC_FILTER "!_*"
>
> This is a hidden rule for users ... please remove it.
> (or, is there any reason why we need to have it?)
>
This is to be in sync with your commit
3c42258c9a4db70133fa6946a275b62a16792bb5
> > +
> > +/*
> > + * uprobe_events only accepts address:
> > + * Convert function and any offset to address
> > + */
> > +static int convert_name_to_addr(struct perf_probe_event *pev, const char *exec)
> > +{
>
> I'm not sure why wouldn't you convert function to "vaddr",
> instead of "exec:vaddr"?
>
If the user provides a symbolic link, convert_name_to_addr would get the
target executable for the given executable. This would handy if we were
to compare existing probes registered on the same application using a
different name (symbolic links). Since you seem to like that we register
with the name the user has provided, I will just feed address here.
--
Thanks and Regards
Srikar
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