From: Daniel Wagner <daniel.wag...@bmw-carit.de>
Whenever a trace is printed the generic fields (CPU, COMM) are
reconstructed (see trace_print_context()). CPU is taken from the
trace_iterator and COMM is extracted from the savedcmd map (see
__trace_find_cmdline()).
We can't reconstruct this information for hist events. Therefore this
information needs to be stored when a new event is added to the hist
buffer.
There is already support for extracting the COMM for the common_pid
field. For this the tracing_map_ops infrasture is used. Unfortunately, we
can't reuse it because it extends an existing hist_field. That means we
first need to add a hist_field before we are able to make reuse of
trace_map_ops.
Furthermore, it is quite easy to extend the current code to support
those two fields by adding hist_field_cpu() and hist_field_comm().
Signed-off-by: Daniel Wagner <daniel.wag...@bmw-carit.de>
---
kernel/trace/trace_events.c | 13 +++++++------
kernel/trace/trace_events_hist.c | 36 ++++++++++++++++++++++++++++++------
2 files changed, 37 insertions(+), 12 deletions(-)
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 03c0a48..ea8da30 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -150,9 +150,10 @@ int trace_define_field(struct trace_event_call *call,
const char *type,
}
EXPORT_SYMBOL_GPL(trace_define_field);
-#define __generic_field(type, item, filter_type) \
+#define __generic_field(type, item, filter_type, size) \
ret = __trace_define_field(&ftrace_generic_fields, #type, \
- #item, 0, 0, is_signed_type(type), \
+ #item, 0, size, \
+ is_signed_type(type), \
filter_type); \
if (ret) \
return ret;
@@ -170,10 +171,10 @@ static int trace_define_generic_fields(void)
{
int ret;
- __generic_field(int, CPU, FILTER_CPU);
- __generic_field(int, cpu, FILTER_CPU);
- __generic_field(char *, COMM, FILTER_COMM);
- __generic_field(char *, comm, FILTER_COMM);
+ __generic_field(int, CPU, FILTER_CPU, sizeof(int));
+ __generic_field(int, cpu, FILTER_CPU, sizeof(int));
+ __generic_field(char *, COMM, FILTER_COMM, TASK_COMM_LEN + 1);
+ __generic_field(char *, comm, FILTER_COMM, TASK_COMM_LEN + 1);
return ret;
}
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index f3a960e..7ed6743 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -75,6 +75,16 @@ static u64 hist_field_log2(struct hist_field *hist_field,
void *event)
return (u64) ilog2(roundup_pow_of_two(val));
}
+static u64 hist_field_cpu(struct hist_field *hist_field, void *event)
+{
+ return (u64) smp_processor_id();
+}
+
+static u64 hist_field_comm(struct hist_field *hist_field, void *event)
+{
+ return (u64) (unsigned long) current->comm;
+}
+
#define DEFINE_HIST_FIELD_FN(type) \
static u64 hist_field_##type(struct hist_field *hist_field, void *event)\
{ \
@@ -119,6 +129,8 @@ enum hist_field_flags {
HIST_FIELD_FL_SYSCALL = 128,
HIST_FIELD_FL_STACKTRACE = 256,
HIST_FIELD_FL_LOG2 = 512,
+ HIST_FIELD_FL_CPU = 1024,
+ HIST_FIELD_FL_COMM = 2048,
};
struct hist_trigger_attrs {
@@ -374,7 +386,13 @@ static struct hist_field *create_hist_field(struct
ftrace_event_field *field,
if (WARN_ON_ONCE(!field))
goto out;
- if (is_string_field(field)) {
+ if (field->filter_type == FILTER_CPU) {
+ flags |= HIST_FIELD_FL_CPU;
+ hist_field->fn = hist_field_cpu;
+ } else if (field->filter_type == FILTER_COMM) {
+ flags |= HIST_FIELD_FL_COMM;
+ hist_field->fn = hist_field_comm;
+ } else if (is_string_field(field)) {
flags |= HIST_FIELD_FL_STRING;
if (field->filter_type == FILTER_STATIC_STRING)
@@ -748,7 +766,8 @@ static int create_tracing_map_fields(struct
hist_trigger_data *hist_data)
if (hist_field->flags & HIST_FIELD_FL_STACKTRACE)
cmp_fn = tracing_map_cmp_none;
- else if (is_string_field(field))
+ else if (is_string_field(field) ||
+ hist_field->flags & HIST_FIELD_FL_COMM)
cmp_fn = tracing_map_cmp_string;
else
cmp_fn = tracing_map_cmp_num(field->size,
@@ -856,11 +875,9 @@ static inline void add_to_key(char *compound_key, void
*key,
struct hist_field *key_field, void *rec)
{
size_t size = key_field->size;
+ struct ftrace_event_field *field = key_field->field;
if (key_field->flags & HIST_FIELD_FL_STRING) {
- struct ftrace_event_field *field;
-
- field = key_field->field;
if (field->filter_type == FILTER_DYN_STRING)
size = *(u32 *)(rec + field->offset) >> 16;
else if (field->filter_type == FILTER_PTR_STRING)
@@ -871,6 +888,8 @@ static inline void add_to_key(char *compound_key, void *key,
/* ensure NULL-termination */
if (size > key_field->size - 1)
size = key_field->size - 1;
+ } else if (field->filter_type == FILTER_STATIC_STRING) {
+ size = field->size;
}
memcpy(compound_key + key_field->offset, key, size);
@@ -906,7 +925,8 @@ static void event_hist_trigger(struct event_trigger_data
*data, void *rec)
key = entries;
} else {
field_contents = key_field->fn(key_field, rec);
- if (key_field->flags & HIST_FIELD_FL_STRING) {
+ if (key_field->flags & (HIST_FIELD_FL_STRING |
+ HIST_FIELD_FL_COMM)) {
key = (void *)(unsigned long)field_contents;
use_compound_key = true;
} else
@@ -1004,6 +1024,10 @@ hist_trigger_entry_print(struct seq_file *m,
} else if (key_field->flags & HIST_FIELD_FL_STRING) {
seq_printf(m, "%s: %-50s", key_field->field->name,
(char *)(key + key_field->offset));
+ } else if (key_field->flags & HIST_FIELD_FL_COMM) {
+ seq_printf(m, "%s: %-16s",
+ key_field->field->name,
+ (char *)(key + key_field->offset));
} else {
uval = *(u64 *)(key + key_field->offset);
seq_printf(m, "%s: %10llu", key_field->field->name,
--
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