tmp = "*";
        else if (tag == DW_TAG_subroutine_type) {
                /* Function pointer */
-               strbuf_addf(buf, "(function_type)");
+               strbuf_add(buf, "(function_type)", 15);
                return 0;
        } else {
                if (!dwarf_diename(&type))
        }
        ret = die_get_typename(&type, buf);
        if (ret == 0)
-               strbuf_addf(buf, "%s", tmp);
+               strbuf_addstr(buf, tmp);
 
        return ret;
 }
        ret = die_get_typename(vr_die, buf);
        if (ret < 0) {
                pr_debug("Failed to get type, make it unknown.\n");
-               strbuf_addf(buf, "(unknown_type)");
+               strbuf_add(buf, " (unknown_type)", 14);
        }
 
        strbuf_addf(buf, "\t%s", dwarf_diename(vr_die));
        }
 
        if (!first)
-               strbuf_addf(buf, "]>");
+               strbuf_add(buf, "]>", 2);
 
 out:
        free(scopes);
        }
 
        if (!first)
-               strbuf_addf(buf, "]>");
+               strbuf_add(buf, "]>", 2);
 
        return ret;
 }
 
                strbuf_addf(result, " in %s", module);
 
        if (pev->nargs > 0) {
-               strbuf_addstr(result, " with");
+               strbuf_add(result, " with", 5);
                for (i = 0; i < pev->nargs; i++) {
                        ret = synthesize_perf_probe_arg(&pev->args[i],
                                                        buf, 128);
 
                        if (probe_conf.show_location_range) {
                                if (!externs) {
                                        if (ret)
-                                               strbuf_addf(&buf, "[INV]\t");
+                                               strbuf_add(&buf, "[INV]\t", 6);
                                        else
-                                               strbuf_addf(&buf, "[VAL]\t");
+                                               strbuf_add(&buf, "[VAL]\t", 6);
                                } else
-                                       strbuf_addf(&buf, "[EXT]\t");
+                                       strbuf_add(&buf, "[EXT]\t", 6);
                        }
 
                        ret2 = die_get_varname(die_mem, &buf);
 
                        if (!ret2 && probe_conf.show_location_range &&
                                !externs) {
-                               strbuf_addf(&buf, "\t");
+                               strbuf_addch(&buf, '\t');
                                ret2 = die_get_var_range(&af->pf.sp_die,
                                                        die_mem, &buf);
                        }