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[PATCH 31/32] tools lib traceevent: Support function __get_dynamic_array_len

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  [PATCH 31/32] tools lib traceevent: Support function __get_dynamic_array_len Wang Nan <wangnan0@huawei.com> - 2015-08-28 09:10 +0200
    Re: [PATCH 31/32] tools lib traceevent: Support function  __get_dynamic_array_len Alexei Starovoitov <ast@plumgrid.com> - 2015-08-29 02:30 +0200

#1215165 — [PATCH 31/32] tools lib traceevent: Support function __get_dynamic_array_len

From: He Kuang <hekuang@huawei.com>

Support helper function __get_dynamic_array_len() in libtraceevent,
this function is used accompany with __print_array() or __print_hex(),
but currently it is not an available function in the function list of
process_function().

The total allocated length of the dynamic array is embedded in the top
half of __data_loc_##item field. This patch adds new arg type
PRINT_DYNAMIC_ARRAY_LEN to return the length to eval_num_arg(),

Signed-off-by: He Kuang <hekuang@huawei.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: pi3orama@163.com
Signed-off-by: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/1437448130-134621-2-git-send-email-hekuang@huawei.com
---
 tools/lib/traceevent/event-parse.c                 | 56 +++++++++++++++++++++-
 tools/lib/traceevent/event-parse.h                 |  1 +
 .../perf/util/scripting-engines/trace-event-perl.c |  1 +
 .../util/scripting-engines/trace-event-python.c    |  1 +
 4 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index 4d88593..1244797 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -848,6 +848,7 @@ static void free_arg(struct print_arg *arg)
 		free(arg->bitmask.bitmask);
 		break;
 	case PRINT_DYNAMIC_ARRAY:
+	case PRINT_DYNAMIC_ARRAY_LEN:
 		free(arg->dynarray.index);
 		break;
 	case PRINT_OP:
@@ -2729,6 +2730,42 @@ process_dynamic_array(struct event_format *event, struct print_arg *arg, char **
 }
 
 static enum event_type
+process_dynamic_array_len(struct event_format *event, struct print_arg *arg,
+			  char **tok)
+{
+	struct format_field *field;
+	enum event_type type;
+	char *token;
+
+	if (read_expect_type(EVENT_ITEM, &token) < 0)
+		goto out_free;
+
+	arg->type = PRINT_DYNAMIC_ARRAY_LEN;
+
+	/* Find the field */
+	field = pevent_find_field(event, token);
+	if (!field)
+		goto out_free;
+
+	arg->dynarray.field = field;
+	arg->dynarray.index = 0;
+
+	if (read_expected(EVENT_DELIM, ")") < 0)
+		goto out_err;
+
+	type = read_token(&token);
+	*tok = token;
+
+	return type;
+
+ out_free:
+	free_token(token);
+ out_err:
+	*tok = NULL;
+	return EVENT_ERROR;
+}
+
+static enum event_type
 process_paren(struct event_format *event, struct print_arg *arg, char **tok)
 {
 	struct print_arg *item_arg;
@@ -2975,6 +3012,10 @@ process_function(struct event_format *event, struct print_arg *arg,
 		free_token(token);
 		return process_dynamic_array(event, arg, tok);
 	}
+	if (strcmp(token, "__get_dynamic_array_len") == 0) {
+		free_token(token);
+		return process_dynamic_array_len(event, arg, tok);
+	}
 
 	func = find_func_handler(event->pevent, token);
 	if (func) {
@@ -3655,14 +3696,25 @@ eval_num_arg(void *data, int size, struct event_format *event, struct print_arg
 			goto out_warning_op;
 		}
 		break;
+	case PRINT_DYNAMIC_ARRAY_LEN:
+		offset = pevent_read_number(pevent,
+					    data + arg->dynarray.field->offset,
+					    arg->dynarray.field->size);
+		/*
+		 * The total allocated length of the dynamic array is
+		 * stored in the top half of the field, and the offset
+		 * is in the bottom half of the 32 bit field.
+		 */
+		val = (unsigned long long)(offset >> 16);
+		break;
 	case PRINT_DYNAMIC_ARRAY:
 		/* Without [], we pass the address to the dynamic data */
 		offset = pevent_read_number(pevent,
 					    data + arg->dynarray.field->offset,
 					    arg->dynarray.field->size);
 		/*
-		 * The actual length of the dynamic array is stored
-		 * in the top half of the field, and the offset
+		 * The total allocated length of the dynamic array is
+		 * stored in the top half of the field, and the offset
 		 * is in the bottom half of the 32 bit field.
 		 */
 		offset &= 0xffff;
diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index 204befb..6fc83c7 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -294,6 +294,7 @@ enum print_arg_type {
 	PRINT_OP,
 	PRINT_FUNC,
 	PRINT_BITMASK,
+	PRINT_DYNAMIC_ARRAY_LEN,
 };
 
 struct print_arg {
diff --git a/tools/perf/util/scripting-engines/trace-event-perl.c b/tools/perf/util/scripting-engines/trace-event-perl.c
index 1bd593b..544509c 100644
--- a/tools/perf/util/scripting-engines/trace-event-perl.c
+++ b/tools/perf/util/scripting-engines/trace-event-perl.c
@@ -221,6 +221,7 @@ static void define_event_symbols(struct event_format *event,
 		break;
 	case PRINT_BSTRING:
 	case PRINT_DYNAMIC_ARRAY:
+	case PRINT_DYNAMIC_ARRAY_LEN:
 	case PRINT_STRING:
 	case PRINT_BITMASK:
 		break;
diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index ace2484..aa9e125 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -251,6 +251,7 @@ static void define_event_symbols(struct event_format *event,
 		/* gcc warns for these? */
 	case PRINT_BSTRING:
 	case PRINT_DYNAMIC_ARRAY:
+	case PRINT_DYNAMIC_ARRAY_LEN:
 	case PRINT_FUNC:
 	case PRINT_BITMASK:
 		/* we should warn... */
-- 
2.1.0

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#1215619 — Re: [PATCH 31/32] tools lib traceevent: Support function __get_dynamic_array_len

On 8/28/15 12:06 AM, Wang Nan wrote:
> From: He Kuang<hekuang@huawei.com>
>
> Support helper function __get_dynamic_array_len() in libtraceevent,
> this function is used accompany with __print_array() or __print_hex(),
> but currently it is not an available function in the function list of
> process_function().
>
> The total allocated length of the dynamic array is embedded in the top
> half of __data_loc_##item field. This patch adds new arg type
> PRINT_DYNAMIC_ARRAY_LEN to return the length to eval_num_arg(),
>
> Signed-off-by: He Kuang<hekuang@huawei.com>
> Acked-by: Namhyung Kim<namhyung@kernel.org>

Tested-by: Alexei Starovoitov <ast@plumgrid.com>

this patch fixes the perf crash:
   Warning: [bpf:bpf_output_data] function __get_dynamic_array_len not 
defined
   Warning: Error: expected type 5 but read 0
*** glibc detected *** perf_4.2.0: double free or corruption (fasttop): 
0x00000000032caf20 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x7ec96)[0x7f0d5d2d3c96]

it's not strictly necessary until patch 32 lands, but I think it's
a good fix regardless.
Steven, could you take it into your tree?

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