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tracing: Allow triggers to filter for CPU ids and process names

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By extending the filter rules by more generic fields
we can write triggers filters like

  echo 'stacktrace if cpu == 1' > \
	/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger

or

  echo 'stacktrace if comm == sshd'  > \
	/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger

CPU and COMM are not part of struct trace_entry. We could add the two
new fields to ftrace_common_field list and fix up all depending
sides. But that looks pretty ugly. Another thing I would like to
avoid that the 'format' file contents changes.

All this can be avoided by introducing another list which contains
non field members of struct trace_entry.

Link: http://lkml.kernel.org/r/1439210146-24707-1-git-send-email-daniel.wagner@bmw-carit.de

Signed-off-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Daniel Wagner 2015-08-10 14:35:46 +02:00 committed by Steven Rostedt
parent c93bf928fe
commit 9f61668073
2 changed files with 77 additions and 2 deletions
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25
kernel/trace/trace_events.c
View File

@ -30,6 +30,7 @@
DEFINE_MUTEX(event_mutex);
LIST_HEAD(ftrace_events);
static LIST_HEAD(ftrace_generic_fields);
static LIST_HEAD(ftrace_common_fields);
#define GFP_TRACE (GFP_KERNEL | __GFP_ZERO)
@ -94,6 +95,10 @@ trace_find_event_field(struct trace_event_call *call, char *name)
struct ftrace_event_field *field;
struct list_head *head;
field = __find_event_field(&ftrace_generic_fields, name);
if (field)
return field;
field = __find_event_field(&ftrace_common_fields, name);
if (field)
return field;
@ -144,6 +149,13 @@ 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) \
ret = __trace_define_field(&ftrace_generic_fields, #type, \
#item, 0, 0, is_signed_type(type), \
filter_type); \
if (ret) \
return ret;
#define __common_field(type, item) \
ret = __trace_define_field(&ftrace_common_fields, #type, \
"common_" #item, \
@ -153,6 +165,16 @@ EXPORT_SYMBOL_GPL(trace_define_field);
if (ret) \
return ret;
static int trace_define_generic_fields(void)
{
int ret;
__generic_field(int, cpu, FILTER_OTHER);
__generic_field(char *, comm, FILTER_PTR_STRING);
return ret;
}
static int trace_define_common_fields(void)
{
int ret;
@ -2671,6 +2693,9 @@ static __init int event_trace_init(void)
if (!entry)
pr_warn("Could not create tracefs 'available_events' entry\n");
if (trace_define_generic_fields())
pr_warn("tracing: Failed to allocated generic fields");
if (trace_define_common_fields())
pr_warn("tracing: Failed to allocate common fields");

54
kernel/trace/trace_events_filter.c
View File

@ -252,6 +252,50 @@ static int filter_pred_strloc(struct filter_pred *pred, void *event)
return match;
}
/* Filter predicate for CPUs. */
static int filter_pred_cpu(struct filter_pred *pred, void *event)
{
int cpu, cmp;
int match = 0;
cpu = raw_smp_processor_id();
cmp = pred->val;
switch (pred->op) {
case OP_EQ:
match = cpu == cmp;
break;
case OP_LT:
match = cpu < cmp;
break;
case OP_LE:
match = cpu <= cmp;
break;
case OP_GT:
match = cpu > cmp;
break;
case OP_GE:
match = cpu >= cmp;
break;
default:
break;
}
return !!match == !pred->not;
}
/* Filter predicate for COMM. */
static int filter_pred_comm(struct filter_pred *pred, void *event)
{
int cmp, match;
cmp = pred->regex.match(current->comm, &pred->regex,
pred->regex.field_len);
match = cmp ^ pred->not;
return match;
}
static int filter_pred_none(struct filter_pred *pred, void *event)
{
return 0;
@ -1002,7 +1046,10 @@ static int init_pred(struct filter_parse_state *ps,
if (is_string_field(field)) {
filter_build_regex(pred);
if (field->filter_type == FILTER_STATIC_STRING) {
if (!strcmp(field->name, "comm")) {
fn = filter_pred_comm;
pred->regex.field_len = TASK_COMM_LEN;
} else if (field->filter_type == FILTER_STATIC_STRING) {
fn = filter_pred_string;
pred->regex.field_len = field->size;
} else if (field->filter_type == FILTER_DYN_STRING)
@ -1025,7 +1072,10 @@ static int init_pred(struct filter_parse_state *ps,
}
pred->val = val;
fn = select_comparison_fn(pred->op, field->size,
if (!strcmp(field->name, "cpu"))
fn = filter_pred_cpu;
else
fn = select_comparison_fn(pred->op, field->size,
field->is_signed);
if (!fn) {
parse_error(ps, FILT_ERR_INVALID_OP, 0);