From 1a891cf19cdfb645827969cc6aeaeebdefeb87b2 Mon Sep 17 00:00:00 2001
From: Steven Rostedt <rostedt@goodmis.org>
Date: Wed, 12 Jun 2013 13:16:25 -0400
Subject: tracing: Add binary '&' filter for events
There are some cases when filtering on a set flag of a field of a tracepoint
is useful. But currently the only filtering commands for numbered fields
is ==, !=, <, <=, >, >=. This does not help when you just want to trace if
a specific flag is set. For example:
> # sudo trace-cmd record -e brcmfmac:brcmf_dbg -f 'level & 0x40000'
> disable all
> enable brcmfmac:brcmf_dbg
> path = /sys/kernel/debug/tracing/events/brcmfmac/brcmf_dbg/enable
> (level & 0x40000)
> ^
> parse_error: Invalid operator
>
When trying to trace brcmf_dbg when level has its 1 << 18 bit set, the
filter fails to perform.
By allowing a binary '&' operation, this gives the user the ability to
test a bit.
Note, a binary '|' is not added, as it doesn't make sense as fields must
be compared to constants (for now), and ORing a constant will always return
true.
Link: http://lkml.kernel.org/r/1371057385.9844.261.camel@gandalf.local.home
Suggested-by: Arend van Spriel <arend@broadcom.com>
Tested-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace_events_filter.c | 6 ++++++
1 file changed, 6 insertions(+)
(limited to 'kernel')
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index e1b653f7e1ca..0d883dc057d6 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -44,6 +44,7 @@ enum filter_op_ids
OP_LE,
OP_GT,
OP_GE,
+ OP_BAND,
OP_NONE,
OP_OPEN_PAREN,
};
@@ -54,6 +55,7 @@ struct filter_op {
int precedence;
};
+/* Order must be the same as enum filter_op_ids above */
static struct filter_op filter_ops[] = {
{ OP_OR, "||", 1 },
{ OP_AND, "&&", 2 },
@@ -64,6 +66,7 @@ static struct filter_op filter_ops[] = {
{ OP_LE, "<=", 5 },
{ OP_GT, ">", 5 },
{ OP_GE, ">=", 5 },
+ { OP_BAND, "&", 6 },
{ OP_NONE, "OP_NONE", 0 },
{ OP_OPEN_PAREN, "(", 0 },
};
@@ -156,6 +159,9 @@ static int filter_pred_##type(struct filter_pred *pred, void *event) \
case OP_GE: \
match = (*addr >= val); \
break; \
+ case OP_BAND: \
+ match = (*addr & val); \
+ break; \
default: \
break; \
} \
--
cgit v1.2.2