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perf probe: Support SDT markers having reference counter (semaphore)

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With this, perf buildid-cache will save SDT markers with reference
counter in probe cache. Perf probe will be able to probe markers
having reference counter. Ex,

  # readelf -n /tmp/tick | grep -A1 loop2
    Name: loop2
    ... Semaphore: 0x0000000010020036

  # ./perf buildid-cache --add /tmp/tick
  # ./perf probe sdt_tick:loop2
  # ./perf stat -e sdt_tick:loop2 /tmp/tick
    hi: 0
    hi: 1
    hi: 2
    ^C
     Performance counter stats for '/tmp/tick':
                 3      sdt_tick:loop2
       2.561851452 seconds time elapsed

Link: http://lkml.kernel.org/r/20180820044250.11659-5-ravi.bangoria@linux.ibm.com

Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Song Liu <songliubraving@fb.com>
Tested-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Ravi Bangoria
2018-08-20 10:12:50 +05:30
committed by Steven Rostedt (VMware)
parent ccea8727dc
commit 5a5e3d3cea
6 changed files with 106 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

39
tools/perf/util/probe-event.c
View File

@@ -1819,6 +1819,12 @@ int parse_probe_trace_command(const char *cmd, struct probe_trace_event *tev)
tp->offset = strtoul(fmt2_str, NULL, 10);
}
if (tev->uprobes) {
fmt2_str = strchr(p, '(');
if (fmt2_str)
tp->ref_ctr_offset = strtoul(fmt2_str + 1, NULL, 0);
}
tev->nargs = argc - 2;
tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
if (tev->args == NULL) {
@@ -2012,6 +2018,22 @@ static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
return err;
}
static int
synthesize_uprobe_trace_def(struct probe_trace_event *tev, struct strbuf *buf)
{
struct probe_trace_point *tp = &tev->point;
int err;
err = strbuf_addf(buf, "%s:0x%lx", tp->module, tp->address);
if (err >= 0 && tp->ref_ctr_offset) {
if (!uprobe_ref_ctr_is_supported())
return -1;
err = strbuf_addf(buf, "(0x%lx)", tp->ref_ctr_offset);
}
return err >= 0 ? 0 : -1;
}
char *synthesize_probe_trace_command(struct probe_trace_event *tev)
{
struct probe_trace_point *tp = &tev->point;
@@ -2041,15 +2063,17 @@ char *synthesize_probe_trace_command(struct probe_trace_event *tev)
}
/* Use the tp->address for uprobes */
if (tev->uprobes)
err = strbuf_addf(&buf, "%s:0x%lx", tp->module, tp->address);
else if (!strncmp(tp->symbol, "0x", 2))
if (tev->uprobes) {
err = synthesize_uprobe_trace_def(tev, &buf);
} else if (!strncmp(tp->symbol, "0x", 2)) {
/* Absolute address. See try_to_find_absolute_address() */
err = strbuf_addf(&buf, "%s%s0x%lx", tp->module ?: "",
tp->module ? ":" : "", tp->address);
else
} else {
err = strbuf_addf(&buf, "%s%s%s+%lu", tp->module ?: "",
tp->module ? ":" : "", tp->symbol, tp->offset);
}
if (err)
goto error;
@@ -2633,6 +2657,13 @@ static void warn_uprobe_event_compat(struct probe_trace_event *tev)
{
int i;
char *buf = synthesize_probe_trace_command(tev);
struct probe_trace_point *tp = &tev->point;
if (tp->ref_ctr_offset && !uprobe_ref_ctr_is_supported()) {
pr_warning("A semaphore is associated with %s:%s and "
"seems your kernel doesn't support it.\n",
tev->group, tev->event);
}
/* Old uprobe event doesn't support memory dereference */
if (!tev->uprobes || tev->nargs == 0 || !buf)