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Subject[PATCH 7/7] perf data: Fix signess of value
Date
From: Wang Nan <wangnan0@huawei.com>

When converting int values, perf first extractes it to a ulonglong, then
feeds it to babeltrace as a signed value. For negative 32 bit values
(for example, return values of failed syscalls), the extracted data
should be something like 0xfffffffe (-2). It becomes a large int64
value. Babeltrace denies to insert it with
bt_ctf_field_signed_integer_set_value() because it is larger than
0x7fffffff, the largest positive value a signed 32 bit int can be.

This patch introduces adjust_signess(), which fills high bits of
ulonglong with 1 if the value is negative.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-bq2fguw8pm8s5rr741mmgias@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
tools/perf/util/data-convert-bt.c | 64 +++++++++++++++++++++++++++++++--------
1 file changed, 52 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index 8eda4ed628e7..977cc3f98d8f 100644
--- a/tools/perf/util/data-convert-bt.c
+++ b/tools/perf/util/data-convert-bt.c
@@ -166,6 +166,43 @@ get_tracepoint_field_type(struct ctf_writer *cw, struct format_field *field)
return cw->data.u32;
}

+static unsigned long long adjust_signess(unsigned long long value_int, int size)
+{
+ unsigned long long value_mask;
+
+ /*
+ * value_mask = (1 << (size * 8 - 1)) - 1.
+ * Directly set value_mask for code readers.
+ */
+ switch (size) {
+ case 1:
+ value_mask = 0x7fULL;
+ break;
+ case 2:
+ value_mask = 0x7fffULL;
+ break;
+ case 4:
+ value_mask = 0x7fffffffULL;
+ break;
+ case 8:
+ /*
+ * For 64 bit value, return it self. There is no need
+ * to fill high bit.
+ */
+ /* Fall through */
+ default:
+ /* BUG! */
+ return value_int;
+ }
+
+ /* If it is a positive value, don't adjust. */
+ if ((value_int & (~0ULL - value_mask)) == 0)
+ return value_int;
+
+ /* Fill upper part of value_int with 1 to make it a negative long long. */
+ return (value_int & value_mask) | ~value_mask;
+}
+
static int add_tracepoint_field_value(struct ctf_writer *cw,
struct bt_ctf_event_class *event_class,
struct bt_ctf_event *event,
@@ -177,7 +214,6 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
struct bt_ctf_field *field;
const char *name = fmtf->name;
void *data = sample->raw_data;
- unsigned long long value_int;
unsigned long flags = fmtf->flags;
unsigned int n_items;
unsigned int i;
@@ -222,11 +258,6 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
type = get_tracepoint_field_type(cw, fmtf);

for (i = 0; i < n_items; i++) {
- if (!(flags & FIELD_IS_STRING))
- value_int = pevent_read_number(
- fmtf->event->pevent,
- data + offset + i * len, len);
-
if (flags & FIELD_IS_ARRAY)
field = bt_ctf_field_array_get_field(array_field, i);
else
@@ -240,12 +271,21 @@ static int add_tracepoint_field_value(struct ctf_writer *cw,
if (flags & FIELD_IS_STRING)
ret = bt_ctf_field_string_set_value(field,
data + offset + i * len);
- else if (!(flags & FIELD_IS_SIGNED))
- ret = bt_ctf_field_unsigned_integer_set_value(
- field, value_int);
- else
- ret = bt_ctf_field_signed_integer_set_value(
- field, value_int);
+ else {
+ unsigned long long value_int;
+
+ value_int = pevent_read_number(
+ fmtf->event->pevent,
+ data + offset + i * len, len);
+
+ if (!(flags & FIELD_IS_SIGNED))
+ ret = bt_ctf_field_unsigned_integer_set_value(
+ field, value_int);
+ else
+ ret = bt_ctf_field_signed_integer_set_value(
+ field, adjust_signess(value_int, len));
+ }
+
if (ret) {
pr_err("failed to set file value %s\n", name);
goto err_put_field;
--
1.9.3


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