Load the global string table data into the strtab BPF map

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Eugene Loh <eugene.loh@oracle.com>

libdtrace/dt_as.c

@@ -567,15 +567,9 @@ dt_as(dt_pcb_t *pcb)
 	 * We keep the string table around (dtp->dt_csstab) because further
 	 * compilations may add more strings.  We will load a consolidated
 	 * compiled string table into a strtab BPF map so it can be used ny
-	 * all BPF programs we will be loading.  Since each DIFO will have a
-	 * string table that comprises the strings of all DIFOs before it along
-	 * with any new ones, we simply assign the latest (and most complete)
-	 * string table to dtp->dt_strtab (and the size as dtp->dt_strlen), so
-	 * that when we are ready to load and execute programs, we know we have
-	 * the latest and greatest string table to work with.
-	 *
-	 * Note that this means that we should *not* free dtp->dt_strtab later
-	 * because it will be free'd when the DIFO is destroyed.
+	 * all BPF programs we will be loading.  Therefore, each DIFO will have
+	 * a string table that comprises the strings of all DIFOs before it
+	 * along with any new ones.
 	 */
 	dp->dtdo_strlen = dt_strtab_size(dtp->dt_ccstab);
 	if (dp->dtdo_strlen > 0) {
@@ -586,9 +580,6 @@ dt_as(dt_pcb_t *pcb)
 		dt_strtab_write(dtp->dt_ccstab,
 				(dt_strtab_write_f *)dt_strtab_copystr,
 				dp->dtdo_strtab);
-
-		dtp->dt_strtab = dp->dtdo_strtab;
-		dtp->dt_strlen = dp->dtdo_strlen;
 	} else
 		dp->dtdo_strtab = NULL;
 

libdtrace/dt_bpf.c

@@ -198,7 +198,7 @@ int
 dt_bpf_gmap_create(dtrace_hdl_t *dtp)
 {
 	int		gvarsz, lvarsz, tvarc, aggsz;
-	int		ci_mapfd;
+	int		ci_mapfd, st_mapfd;
 	uint32_t	key = 0;
 
 	/* If we already created the global maps, return success. */
@@ -251,8 +251,21 @@ dt_bpf_gmap_create(dtrace_hdl_t *dtp)
 				roundup(dtp->dt_maxreclen, 8), 1) == -1)
 		return -1;		/* dt_errno is set for us */
 
-	if (create_gmap(dtp, "strtab", BPF_MAP_TYPE_ARRAY,
-			sizeof(uint32_t), dtp->dt_strlen, 1) == -1)
+	/*
+	 * We may need to create a final copy of the string table because it is
+	 * possible entries were added after the last clause was compiled.
+	 */
+	dtp->dt_strlen = dt_strtab_size(dtp->dt_ccstab);
+	dtp->dt_strtab = dt_zalloc(dtp, dtp->dt_strlen);
+	if (dtp->dt_strtab == NULL)
+		return dt_set_errno(dtp, EDT_NOMEM);
+
+	dt_strtab_write(dtp->dt_ccstab, (dt_strtab_write_f *)dt_strtab_copystr,
+			dtp->dt_strtab);
+
+	st_mapfd = create_gmap(dtp, "strtab", BPF_MAP_TYPE_ARRAY,
+			       sizeof(uint32_t), dtp->dt_strlen, 1);
+	if (st_mapfd == -1)
 		return -1;		/* dt_errno is set for us */
 
 	if (gvarsz > 0 &&
@@ -273,6 +286,9 @@ dt_bpf_gmap_create(dtrace_hdl_t *dtp)
 	/* Populate the 'cpuinfo' map. */
 	dt_bpf_map_update(ci_mapfd, &key, dtp->dt_conf.cpus);
 
+	/* Populate the 'strtab' map. */
+	dt_bpf_map_update(st_mapfd, &key, dtp->dt_strtab);
+
 	/* Set some task_struct offsets in state. */
 	if (set_task_offsets(dtp))
 		return dt_set_errno(dtp, EDT_CTF);