Re: [PATCH v3 9/9] perf probe: Support SDT markers having reference counter (semaphore)

[Masami Hiramatsu]

On Tue, 17 Apr 2018 10:02:44 +0530
Ravi Bangoria  wrote:

> From: Ravi Bangoria 
> 
> 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: 0x10020036
> 
>   # ./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
> 
> Signed-off-by: Ravi Bangoria 

Looks good to me.

Acked-by: Masami Hiramatsu 

Thanks!

> ---
>  tools/perf/util/probe-event.c | 39 
>  tools/perf/util/probe-event.h |  1 +
>  tools/perf/util/probe-file.c  | 34 ++--
>  tools/perf/util/probe-file.h  |  1 +
>  tools/perf/util/symbol-elf.c  | 46 
> ---
>  tools/perf/util/symbol.h  |  7 +++
>  6 files changed, 106 insertions(+), 22 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index e1dbc98..9b9c26e 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1832,6 +1832,12 @@ 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) {
> @@ -2025,6 +2031,22 @@ 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 = >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 = >point;
> @@ -2054,15 +2076,17 @@ char *synthesize_probe_trace_command(struct 
> probe_trace_event *tev)
>   }
>  
>   /* Use the tp->address for uprobes */
> - if (tev->uprobes)
> - err = strbuf_addf(, "%s:0x%lx", tp->module, tp->address);
> - else if (!strncmp(tp->symbol, "0x", 2))
> + if (tev->uprobes) {
> + err = synthesize_uprobe_trace_def(tev, );
> + } else if (!strncmp(tp->symbol, "0x", 2)) {
>   /* Absolute address. See try_to_find_absolute_address() */
>   err = strbuf_addf(, "%s%s0x%lx", tp->module ?: "",
> tp->module ? ":" : "", tp->address);
> - else
> + } else {
>   err = strbuf_addf(, "%s%s%s+%lu", tp->module ?: "",
>   tp->module ? ":" : "", tp->symbol, tp->offset);
> + }
> +
>   if (err)
>   goto error;
>  
> @@ -2646,6 +2670,13 @@ 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 = >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)
> diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
> index 45b14f0..15a98c3 100644
> --- a/tools/perf/util/probe-event.h
> +++ b/tools/perf/util/probe-event.h
> @@ -27,6 +27,7 @@ struct probe_trace_point {
>   char*symbol;/* Base symbol */
>   char*module;/* Module name */
>   unsigned long   offset; /* Offset from symbol */
> + unsigned long   ref_ctr_offset; /* SDT reference counter offset */
>   unsigned long   address;/* Actual address of the trace point */
>   boolretprobe;   /* Return probe flag */
>  };
> diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> index 4ae1123..a17ba6a 100644

[PATCH v3 9/9] perf probe: Support SDT markers having reference counter (semaphore)

[Ravi Bangoria]

From: Ravi Bangoria 

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: 0x10020036

  # ./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

Signed-off-by: Ravi Bangoria 
---
 tools/perf/util/probe-event.c | 39 
 tools/perf/util/probe-event.h |  1 +
 tools/perf/util/probe-file.c  | 34 ++--
 tools/perf/util/probe-file.h  |  1 +
 tools/perf/util/symbol-elf.c  | 46 ---
 tools/perf/util/symbol.h  |  7 +++
 6 files changed, 106 insertions(+), 22 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index e1dbc98..9b9c26e 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1832,6 +1832,12 @@ 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) {
@@ -2025,6 +2031,22 @@ 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 = >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 = >point;
@@ -2054,15 +2076,17 @@ char *synthesize_probe_trace_command(struct 
probe_trace_event *tev)
}
 
/* Use the tp->address for uprobes */
-   if (tev->uprobes)
-   err = strbuf_addf(, "%s:0x%lx", tp->module, tp->address);
-   else if (!strncmp(tp->symbol, "0x", 2))
+   if (tev->uprobes) {
+   err = synthesize_uprobe_trace_def(tev, );
+   } else if (!strncmp(tp->symbol, "0x", 2)) {
/* Absolute address. See try_to_find_absolute_address() */
err = strbuf_addf(, "%s%s0x%lx", tp->module ?: "",
  tp->module ? ":" : "", tp->address);
-   else
+   } else {
err = strbuf_addf(, "%s%s%s+%lu", tp->module ?: "",
tp->module ? ":" : "", tp->symbol, tp->offset);
+   }
+
if (err)
goto error;
 
@@ -2646,6 +2670,13 @@ 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 = >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)
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index 45b14f0..15a98c3 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -27,6 +27,7 @@ struct probe_trace_point {
char*symbol;/* Base symbol */
char*module;/* Module name */
unsigned long   offset; /* Offset from symbol */
+   unsigned long   ref_ctr_offset; /* SDT reference counter offset */
unsigned long   address;/* Actual address of the trace point */
boolretprobe;   /* Return probe flag */
 };
diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
index 4ae1123..a17ba6a 100644
--- a/tools/perf/util/probe-file.c
+++ b/tools/perf/util/probe-file.c
@@ -697,8 +697,16 @@ int probe_cache__add_entry(struct probe_cache *pcache,
 #ifdef HAVE_GELF_GETNOTE_SUPPORT
 static unsigned long long sdt_note__get_addr(struct sdt_note *note)
 {
-   return note->bit32 ? (unsigned long