diff options
| author | Steven Rostedt (Red Hat) <rostedt@goodmis.org> | 2014-12-02 11:55:36 -0500 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2014-12-03 10:00:13 -0500 |
| commit | e12c09cf3087b5a184ffeb55ca368e8aa436a3a2 (patch) | |
| tree | edaefaee5f456a84484ccf40ae8b84f41228253f | |
| parent | 6a06bdbf7f9c669743f58084991ba280f2925586 (diff) | |
tracing: Add NOT to filtering logic
Ted noticed that he could not filter on an event for a bit being cleared.
That's because the filtering logic only tests event fields with a limited
number of comparisons which, for bit logic, only include "&", which can
test if a bit is set, but there's no good way to see if a bit is clear.
This adds a way to do: !(field & 2048)
Which returns true if the bit is not set, and false otherwise.
Note, currently !(field1 == 10 && field2 == 15) is not supported.
That is, the 'not' only works for direct comparisons, not for the
AND and OR logic.
Link: http://lkml.kernel.org/r/20141202021912.GA29096@thunk.org
Link: http://lkml.kernel.org/r/20141202120430.71979060@gandalf.local.home
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Suggested-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
| -rw-r--r-- | kernel/trace/trace_events_filter.c | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 7a8c1528e141..e6a33db83856 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -45,6 +45,7 @@ enum filter_op_ids OP_GT, OP_GE, OP_BAND, + OP_NOT, OP_NONE, OP_OPEN_PAREN, }; @@ -67,6 +68,7 @@ static struct filter_op filter_ops[] = { { OP_GT, ">", 5 }, { OP_GE, ">=", 5 }, { OP_BAND, "&", 6 }, + { OP_NOT, "!", 6 }, { OP_NONE, "OP_NONE", 0 }, { OP_OPEN_PAREN, "(", 0 }, }; @@ -85,6 +87,7 @@ enum { FILT_ERR_MISSING_FIELD, FILT_ERR_INVALID_FILTER, FILT_ERR_IP_FIELD_ONLY, + FILT_ERR_ILLEGAL_NOT_OP, }; static char *err_text[] = { @@ -101,6 +104,7 @@ static char *err_text[] = { "Missing field name and/or value", "Meaningless filter expression", "Only 'ip' field is supported for function trace", + "Illegal use of '!'", }; struct opstack_op { @@ -139,6 +143,7 @@ struct pred_stack { int index; }; +/* If not of not match is equal to not of not, then it is a match */ #define DEFINE_COMPARISON_PRED(type) \ static int filter_pred_##type(struct filter_pred *pred, void *event) \ { \ @@ -166,7 +171,7 @@ static int filter_pred_##type(struct filter_pred *pred, void *event) \ break; \ } \ \ - return match; \ + return !!match == !pred->not; \ } #define DEFINE_EQUALITY_PRED(size) \ @@ -1028,7 +1033,7 @@ static int init_pred(struct filter_parse_state *ps, } if (pred->op == OP_NE) - pred->not = 1; + pred->not ^= 1; pred->fn = fn; return 0; @@ -1590,6 +1595,17 @@ static int replace_preds(struct ftrace_event_call *call, continue; } + if (elt->op == OP_NOT) { + if (!n_preds || operand1 || operand2) { + parse_error(ps, FILT_ERR_ILLEGAL_NOT_OP, 0); + err = -EINVAL; + goto fail; + } + if (!dry_run) + filter->preds[n_preds - 1].not ^= 1; + continue; + } + if (WARN_ON(n_preds++ == MAX_FILTER_PRED)) { parse_error(ps, FILT_ERR_TOO_MANY_PREDS, 0); err = -ENOSPC; |