libipt: fix blk and insn timing queries

When implementing the block decoder on top of the event decoder in

    ed9222c libipt: blk on evt

we dropped

    -pte_no_time
    -pte_no_cbr

error returns when no TSC/CBR has been seen.

This bug was later inherited by the insn decoder in

    8b90e05 libipt, ptxed: insn on block

when we implemented that on top of the block decoder.

We already track whether we have seen TSC, but we're not using it in
pt_blk_time().  Fix that and add tracking for CBR.

Fixes #116.

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>

Author: markus-metzger

libipt/internal/include/pt_block_decoder.h

@@ -132,6 +132,9 @@ struct pt_block_decoder {
 	/* - whether @tsc tracks wall-clock time. */
 	uint32_t has_tsc:1;
 
+	/* - whether @cbr is valid. */
+	uint32_t has_cbr:1;
+
 	/* - whether @icnt is valid. */
 	uint32_t has_icnt:1;
 

libipt/src/pt_block_decoder.c

@@ -200,6 +200,7 @@ static int pt_blk_reset(struct pt_block_decoder *decoder)
 	decoder->enabled = 0;
 	decoder->speculative = 0;
 	decoder->has_tsc = 0;
+	decoder->has_cbr = 0;
 	decoder->has_icnt = 0;
 	decoder->process_insn = 0;
 	decoder->bound_paging = 0;
@@ -643,6 +644,9 @@ int pt_blk_time(struct pt_block_decoder *decoder, uint64_t *time,
 	*lost_mtc = decoder->lost_mtc;
 	*lost_cyc = decoder->lost_cyc;
 
+	if (!decoder->has_tsc)
+		return -pte_no_time;
+
 	return 0;
 }
 
@@ -651,6 +655,9 @@ int pt_blk_core_bus_ratio(struct pt_block_decoder *decoder, uint32_t *cbr)
 	if (!decoder || !cbr)
 		return -pte_invalid;
 
+	if (!decoder->has_cbr)
+		return -pte_no_cbr;
+
 	*cbr = decoder->cbr;
 
 	return 0;
@@ -4147,6 +4154,7 @@ static int pt_blk_process_cbr(struct pt_block_decoder *decoder,
 	if (!decoder || !ev)
 		return -pte_internal;
 
+	decoder->has_cbr = 1;
 	decoder->cbr = ev->variant.cbr.ratio;
 
 	return 0;

libipt/test/src/ptunit-block_decoder.c

@@ -272,6 +272,29 @@ static struct ptunit_result cbr_null(void)
 	return ptu_passed();
 }
 
+static struct ptunit_result time_init(struct test_fixture *tfix)
+{
+	uint64_t time;
+	uint32_t lost_mtc, lost_cyc;
+	int errcode;
+
+	errcode = pt_blk_time(&tfix->decoder, &time, &lost_mtc, &lost_cyc);
+	ptu_int_eq(errcode, -pte_no_time);
+
+	return ptu_passed();
+}
+
+static struct ptunit_result cbr_init(struct test_fixture *tfix)
+{
+	uint32_t cbr;
+	int errcode;
+
+	errcode = pt_blk_core_bus_ratio(&tfix->decoder, &cbr);
+	ptu_int_eq(errcode, -pte_no_cbr);
+
+	return ptu_passed();
+}
+
 static struct ptunit_result asid_null(void)
 {
 	struct pt_block_decoder decoder;
@@ -351,6 +374,9 @@ int main(int argc, char **argv)
 	ptu_run(suite, cbr_null);
 	ptu_run(suite, asid_null);
 
+	ptu_run_f(suite, time_init, tfix);
+	ptu_run_f(suite, cbr_init, tfix);
+
 	ptu_run(suite, next_null);
 	ptu_run(suite, event_null);