usdt, stapsdt: fix argument handling for multi-location probes

When a USDT probe has multiple call sites in the same function, only one of the probe programs retrieves the argument values correctly. The probe argument data is collected for the first underlying probe, and then skipped for any subsequent underlying probes.

Since it is not guaranteed that the argument description is identical for all underlying probes (although it is almost always that way), we need to process the argument description string for each underlying probe.

Orabug: 38922360

---
 libdtrace/dt_pid.c                            |  9 ++-
 libdtrace/dt_prov_uprobe.c                    | 10 +--
 test/unittest/usdt/tst.multiloc.r             |  4 ++
 test/unittest/usdt/tst.multiloc.sh            | 69 +++++++++++++++++++
 .../usdt/tst.stapsdt-notes-bug38922360.r      |  4 ++
 .../usdt/tst.stapsdt-notes-bug38922360.sh     | 54 +++++++++++++++
 6 files changed, 140 insertions(+), 10 deletions(-)
 create mode 100644 test/unittest/usdt/tst.multiloc.r
 create mode 100755 test/unittest/usdt/tst.multiloc.sh
 create mode 100644 test/unittest/usdt/tst.stapsdt-notes-bug38922360.r
 create mode 100755 test/unittest/usdt/tst.stapsdt-notes-bug38922360.sh

index 6f93123f..a379a0fe 100644
@@ -1350,9 +1350,16 @@ dt_stapsdt_parse(dtrace_hdl_t *dtp, dt_proc_t *dpr, dtrace_probedesc_t *pdp,
 		if (strcmp(pdp->prb, "*") != 0 &&
 		    (strlen(pdp->prb) > 0 && strcmp(pdp->prb, prbname) != 0))
 			continue;
-		if (prb + strlen(prb) + 1 < dbuf + doff + nhdr.n_descsz)
+		if (prb + strlen(prb) + 1 < dbuf + doff + nhdr.n_descsz) {
+			char	*p;
+
 			psp.pps_sargv = prb + strlen(prb) + 1;
 
+			for (p = psp.pps_sargv; (p = strchr(p, '@')) != NULL;
+			     p++)
+				psp.pps_nargc++;
+		}
+
 		psp.pps_type = DTPPT_STAPSDT;
 		psp.pps_prv = prvname;
 		psp.pps_mod = mod;

index 6d1c0f65..e575b072 100644
@@ -1659,15 +1659,7 @@ static int probe_info_stap(dtrace_hdl_t *dtp, const dt_probe_t *prp,
 	if (!upp || upp->sargv == NULL)
 		goto done;
 
-	/* First count the arguments. */
-	for (p = upp->sargv; p != NULL; argc++) {
-		p = strchr(p, '@');
-		if (p++ == NULL)
-			break;
-	}
-
-	/* Record number of arguments, and allocate descriptors. */
-	upp->sargc = argc;
+	argc = upp->sargc;
 	if (argc == 0)
 		goto done;
 

new file mode 100644
index 00000000..a0bbc7a8
@@ -0,0 +1,4 @@
+main
+test:main:args main
+test:main:args main
+

new file mode 100644
index 00000000..a0bbc7a8
@@ -0,0 +1,4 @@
+main
+test:main:args main
+test:main:args main
+

2.51.0