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tracing: Add binary '&' filter for events

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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>
This commit is contained in:
Steven Rostedt 2013-06-12 13:16:25 -04:00
parent aaf6ac0f08
commit 1a891cf19c
2 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/trace/events.txt
View File

@ -183,7 +183,7 @@ The relational-operators depend on the type of the field being tested:
The operators available for numeric fields are:
==, !=, <, <=, >, >=
==, !=, <, <=, >, >=, &
And for string fields they are:

6
kernel/trace/trace_events_filter.c
View File

@ -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; \
} \