For > 8 byte values, allow simple binary '==', '!=' predicates where the user passes in a hex ASCII representation of the desired value. The representation must match the field size exactly, and a simple memory comparison between predicate and actual value is carried out. For example:
cd /sys/kernel/debug/tracing/events/tcp/tcp_receive_reset echo "saddr_v6 == 0x00000000000000000000000000000001" > filter
Signed-off-by: Alan Maguire alan.maguire@oracle.com --- kernel/trace/trace_events_filter.c | 54 +++++++++++++++++++++++++++++- 1 file changed, 53 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c index 1dad64267878..64f1dfb72cb5 100644 --- a/kernel/trace/trace_events_filter.c +++ b/kernel/trace/trace_events_filter.c @@ -67,6 +67,7 @@ enum filter_pred_fn { FILTER_PRED_FN_FUNCTION, FILTER_PRED_FN_, FILTER_PRED_TEST_VISITED, + FILTER_PRED_FN_MEMCMP, };
struct filter_pred { @@ -622,8 +623,11 @@ predicate_parse(const char *str, int nr_parens, int nr_preds, kfree(op_stack); kfree(inverts); if (prog_stack) { - for (i = 0; prog_stack[i].pred; i++) + for (i = 0; prog_stack[i].pred; i++) { + if (prog_stack[i].pred->fn_num == FILTER_PRED_FN_MEMCMP) + kfree((u8 *)(uintptr_t)(prog_stack[i].pred->val)); kfree(prog_stack[i].pred); + } kfree(prog_stack); } return ERR_PTR(ret); @@ -890,6 +894,14 @@ static int filter_pred_function(struct filter_pred *pred, void *event) return pred->op == OP_EQ ? ret : !ret; }
+static int filter_pred_memcmp(struct filter_pred *pred, void *event) +{ + u8 *mem = (u8 *)(event + pred->offset); + u8 *cmp = (u8 *)(uintptr_t)(pred->val); + + return (memcmp(mem, cmp, pred->field->size) == 0) ^ pred->not; +} + /* * regex_match_foo - Basic regex callbacks * @@ -1353,6 +1365,8 @@ static int filter_pred_fn_call(struct filter_pred *pred, void *event) return filter_pred_function(pred, event); case FILTER_PRED_TEST_VISITED: return test_pred_visited_fn(pred, event); + case FILTER_PRED_FN_MEMCMP: + return filter_pred_memcmp(pred, event); default: return 0; } @@ -1370,6 +1384,7 @@ static int parse_pred(const char *str, void *data, unsigned long size; unsigned long ip; char num_buf[24]; /* Big enough to hold an address */ + u8 *pred_val; char *field_name; char *name; bool function = false; @@ -1631,6 +1646,43 @@ static int parse_pred(const char *str, void *data, /* go past the last quote */ i++;
+ } else if (str[i] == '0' && tolower(str[i + 1]) == 'x' && + field->size > 8) { + /* For sizes > 8 bytes, we store hex bytes for comparison; + * only '==' and '!=' are supported. + * To keep things simple, the predicate value must specify + * a value that matches the field size exactly, with leading + * 0s if necessary. + */ + if (pred->op != OP_EQ && pred->op != OP_NE) { + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + i); + goto err_free; + } + + /* skip required 0x */ + s += 2; + i += 2; + + while (isalnum(str[i])) + i++; + + len = i - s; + if (len != (field->size * 2)) { + parse_error(pe, FILT_ERR_ILLEGAL_FIELD_OP, pos + s); + goto err_free; + } + + pred_val = kzalloc(field->size, GFP_KERNEL); + if (hex2bin(pred_val, str + s, field->size)) { + parse_error(pe, FILT_ERR_ILLEGAL_INTVAL, pos + s); + kfree(pred_val); + goto err_free; + } + pred->val = (u64)pred_val; + pred->fn_num = FILTER_PRED_FN_MEMCMP; + if (pred->op == OP_NE) + pred->not = 1; + } else if (isdigit(str[i]) || str[i] == '-') {
/* Make sure the field is not a string */