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tracing/filters: support for filters of dynamic sized arrays

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Currently the filtering infrastructure supports well the
numeric types and fixed sized array types.

But the recently added __string() field uses a specific
indirect offset mechanism which requires a specific
predicate. Until now it wasn't supported.

This patch adds this support and implies very few changes,
only a new predicate is needed, the management of this specific
field can be done through the usual string helpers in the
filtering infrastructure.

[ Impact: support all kinds of strings in the tracing filters ]

Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Zhaolei <zhaolei@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
This commit is contained in:
Frederic Weisbecker 2009-05-03 02:48:52 +02:00 committed by Ingo Molnar
parent 8ae79a138e
commit e8808c1019
1 changed files with 41 additions and 3 deletions
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44
kernel/trace/trace_events_filter.c
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@ -151,6 +151,7 @@ static int filter_pred_or(struct filter_pred *pred __attribute((unused)),
return val1 || val2;
}
/* Filter predicate for fixed sized arrays of characters */
static int filter_pred_string(struct filter_pred *pred, void *event,
int val1, int val2)
{
@ -164,6 +165,30 @@ static int filter_pred_string(struct filter_pred *pred, void *event,
return match;
}
/*
* Filter predicate for dynamic sized arrays of characters.
* These are implemented through a list of strings at the end
* of the entry.
* Also each of these strings have a field in the entry which
* contains its offset from the beginning of the entry.
* We have then first to get this field, dereference it
* and add it to the address of the entry, and at last we have
* the address of the string.
*/
static int filter_pred_strloc(struct filter_pred *pred, void *event,
int val1, int val2)
{
int str_loc = *(int *)(event + pred->offset);
char *addr = (char *)(event + str_loc);
int cmp, match;
cmp = strncmp(addr, pred->str_val, pred->str_len);
match = (!cmp) ^ pred->not;
return match;
}
static int filter_pred_none(struct filter_pred *pred, void *event,
int val1, int val2)
{
@ -446,10 +471,18 @@ static int filter_add_pred_fn(struct filter_parse_state *ps,
return 0;
}
enum {
FILTER_STATIC_STRING = 1,
FILTER_DYN_STRING
};
static int is_string_field(const char *type)
{
if (strchr(type, '[') && strstr(type, "char"))
return 1;
return FILTER_STATIC_STRING;
if (!strcmp(type, "__str_loc"))
return FILTER_DYN_STRING;
return 0;
}
@ -512,6 +545,7 @@ static int filter_add_pred(struct filter_parse_state *ps,
struct ftrace_event_field *field;
filter_pred_fn_t fn;
unsigned long long val;
int string_type;
pred->fn = filter_pred_none;
@ -536,8 +570,12 @@ static int filter_add_pred(struct filter_parse_state *ps,
return -EINVAL;
}
if (is_string_field(field->type)) {
fn = filter_pred_string;
string_type = is_string_field(field->type);
if (string_type) {
if (string_type == FILTER_STATIC_STRING)
fn = filter_pred_string;
else
fn = filter_pred_strloc;
pred->str_len = field->size;
if (pred->op == OP_NE)
pred->not = 1;