+ kfree(chan->sc_filter);
+ return 0;
+}
+
+static
+int get_syscall_nr(const char *syscall_name)
+{
+ int syscall_nr = -1;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(sc_table); i++) {
+ const struct trace_syscall_entry *entry;
+
+ entry = &sc_table[i];
+ if (!entry->desc)
+ continue;
+ if (!strcmp(syscall_name, entry->desc->name)) {
+ syscall_nr = i;
+ break;
+ }
+ }
+ return syscall_nr;
+}
+
+static
+int get_compat_syscall_nr(const char *syscall_name)
+{
+ int syscall_nr = -1;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(compat_sc_table); i++) {
+ const struct trace_syscall_entry *entry;
+
+ entry = &compat_sc_table[i];
+ if (!entry->desc)
+ continue;
+ if (!strcmp(syscall_name, entry->desc->name)) {
+ syscall_nr = i;
+ break;
+ }
+ }
+ return syscall_nr;
+}
+
+int lttng_syscall_filter_enable(struct lttng_channel *chan,
+ const char *name)
+{
+ int syscall_nr, compat_syscall_nr, ret;
+ struct lttng_syscall_filter *filter;
+
+ WARN_ON_ONCE(!chan->sc_table);
+
+ if (!name) {
+ /* Enable all system calls by removing filter */
+ if (chan->sc_filter) {
+ filter = chan->sc_filter;
+ rcu_assign_pointer(chan->sc_filter, NULL);
+ synchronize_trace();
+ kfree(filter);
+ }
+ chan->syscall_all = 1;
+ return 0;
+ }
+
+ if (!chan->sc_filter) {
+ if (chan->syscall_all) {
+ /*
+ * All syscalls are already enabled.
+ */
+ return -EEXIST;
+ }
+ filter = kzalloc(sizeof(struct lttng_syscall_filter),
+ GFP_KERNEL);
+ if (!filter)
+ return -ENOMEM;
+ } else {
+ filter = chan->sc_filter;
+ }
+ syscall_nr = get_syscall_nr(name);
+ compat_syscall_nr = get_compat_syscall_nr(name);
+ if (syscall_nr < 0 && compat_syscall_nr < 0) {
+ ret = -ENOENT;
+ goto error;
+ }
+ if (syscall_nr >= 0) {
+ if (test_bit(syscall_nr, filter->sc)) {
+ ret = -EEXIST;
+ goto error;
+ }
+ bitmap_set(filter->sc, syscall_nr, 1);
+ }
+ if (compat_syscall_nr >= 0) {
+ if (test_bit(compat_syscall_nr, filter->sc_compat)) {
+ ret = -EEXIST;
+ goto error;
+ }
+ bitmap_set(filter->sc_compat, compat_syscall_nr, 1);
+ }
+ if (!chan->sc_filter)
+ rcu_assign_pointer(chan->sc_filter, filter);
+ return 0;
+
+error:
+ if (!chan->sc_filter)
+ kfree(filter);
+ return ret;
+}
+
+int lttng_syscall_filter_disable(struct lttng_channel *chan,
+ const char *name)
+{
+ int syscall_nr, compat_syscall_nr, ret;
+ struct lttng_syscall_filter *filter;
+
+ WARN_ON_ONCE(!chan->sc_table);
+
+ if (!chan->sc_filter) {
+ filter = kzalloc(sizeof(struct lttng_syscall_filter),
+ GFP_KERNEL);
+ if (!filter)
+ return -ENOMEM;
+ /* Trace all system calls, then apply disable. */
+ bitmap_set(filter->sc, 0, NR_syscalls);
+ bitmap_set(filter->sc_compat, 0, NR_compat_syscalls);
+ } else {
+ filter = chan->sc_filter;
+ }
+
+ syscall_nr = get_syscall_nr(name);
+ compat_syscall_nr = get_compat_syscall_nr(name);
+ if (syscall_nr < 0 && compat_syscall_nr < 0) {
+ ret = -ENOENT;
+ goto error;
+ }
+ if (syscall_nr >= 0) {
+ if (!test_bit(syscall_nr, chan->sc_filter->sc)) {
+ ret = -EEXIST;
+ goto error;
+ }
+ bitmap_clear(chan->sc_filter->sc, syscall_nr, 1);
+ }
+ if (compat_syscall_nr >= 0) {
+ if (!test_bit(compat_syscall_nr, chan->sc_filter->sc_compat)) {
+ ret = -EEXIST;
+ goto error;
+ }
+ bitmap_clear(chan->sc_filter->sc_compat, compat_syscall_nr, 1);
+ }
+ if (!chan->sc_filter)
+ rcu_assign_pointer(chan->sc_filter, filter);
+ chan->syscall_all = 0;