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authorBenjamin Tissoires <bentiss@kernel.org>2024-04-20 11:09:11 +0200
committerAlexei Starovoitov <ast@kernel.org>2024-04-24 04:46:57 +0200
commiteb48f6cd41a0f7803770a76bbffb6bd5b1b2ae2f (patch)
tree46da490f63b2559a7d0915df149ab549f7ab0fdf /kernel/bpf/helpers.c
parentselftests/bpf: add bpf_wq tests (diff)
downloadlinux-eb48f6cd41a0f7803770a76bbffb6bd5b1b2ae2f.tar.xz
linux-eb48f6cd41a0f7803770a76bbffb6bd5b1b2ae2f.zip
bpf: wq: add bpf_wq_init
We need to teach the verifier about the second argument which is declared as void * but which is of type KF_ARG_PTR_TO_MAP. We could have dropped this extra case if we declared the second argument as struct bpf_map *, but that means users will have to do extra casting to have their program compile. We also need to duplicate the timer code for the checking if the map argument is matching the provided workqueue. Signed-off-by: Benjamin Tissoires <bentiss@kernel.org> Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-11-6c986a5a741f@kernel.org Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/helpers.c')
-rw-r--r--kernel/bpf/helpers.c104
1 files changed, 102 insertions, 2 deletions
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index fe827f6e5234..1fc002cfe2b1 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -1109,11 +1109,18 @@ struct bpf_hrtimer {
struct hrtimer timer;
};
-/* the actual struct hidden inside uapi struct bpf_timer */
+struct bpf_work {
+ struct bpf_async_cb cb;
+ struct work_struct work;
+ struct work_struct delete_work;
+};
+
+/* the actual struct hidden inside uapi struct bpf_timer and bpf_wq */
struct bpf_async_kern {
union {
struct bpf_async_cb *cb;
struct bpf_hrtimer *timer;
+ struct bpf_work *work;
};
/* bpf_spin_lock is used here instead of spinlock_t to make
* sure that it always fits into space reserved by struct bpf_timer
@@ -1124,6 +1131,7 @@ struct bpf_async_kern {
enum bpf_async_type {
BPF_ASYNC_TYPE_TIMER = 0,
+ BPF_ASYNC_TYPE_WQ,
};
static DEFINE_PER_CPU(struct bpf_hrtimer *, hrtimer_running);
@@ -1167,11 +1175,64 @@ out:
return HRTIMER_NORESTART;
}
+static void bpf_wq_work(struct work_struct *work)
+{
+ struct bpf_work *w = container_of(work, struct bpf_work, work);
+ struct bpf_tramp_run_ctx __maybe_unused run_ctx;
+ struct bpf_async_cb *cb = &w->cb;
+ struct bpf_prog *prog = cb->prog;
+ struct bpf_map *map = cb->map;
+ bpf_callback_t callback_fn;
+ void *value = cb->value;
+ void *key;
+ u32 idx;
+
+ BTF_TYPE_EMIT(struct bpf_wq);
+
+ callback_fn = READ_ONCE(cb->callback_fn);
+ if (!callback_fn || !prog)
+ return;
+
+ if (map->map_type == BPF_MAP_TYPE_ARRAY) {
+ struct bpf_array *array = container_of(map, struct bpf_array, map);
+
+ /* compute the key */
+ idx = ((char *)value - array->value) / array->elem_size;
+ key = &idx;
+ } else { /* hash or lru */
+ key = value - round_up(map->key_size, 8);
+ }
+
+ run_ctx.bpf_cookie = 0;
+
+ if (!__bpf_prog_enter_sleepable_recur(prog, &run_ctx)) {
+ /* recursion detected */
+ __bpf_prog_exit_sleepable_recur(prog, 0, &run_ctx);
+ return;
+ }
+
+ callback_fn((u64)(long)map, (u64)(long)key, (u64)(long)value, 0, 0);
+ /* The verifier checked that return value is zero. */
+
+ __bpf_prog_exit_sleepable_recur(prog, 0 /* bpf_prog_run does runtime stats */,
+ &run_ctx);
+}
+
+static void bpf_wq_delete_work(struct work_struct *work)
+{
+ struct bpf_work *w = container_of(work, struct bpf_work, delete_work);
+
+ cancel_work_sync(&w->work);
+
+ kfree_rcu(w, cb.rcu);
+}
+
static int __bpf_async_init(struct bpf_async_kern *async, struct bpf_map *map, u64 flags,
enum bpf_async_type type)
{
struct bpf_async_cb *cb;
struct bpf_hrtimer *t;
+ struct bpf_work *w;
clockid_t clockid;
size_t size;
int ret = 0;
@@ -1183,6 +1244,9 @@ static int __bpf_async_init(struct bpf_async_kern *async, struct bpf_map *map, u
case BPF_ASYNC_TYPE_TIMER:
size = sizeof(struct bpf_hrtimer);
break;
+ case BPF_ASYNC_TYPE_WQ:
+ size = sizeof(struct bpf_work);
+ break;
default:
return -EINVAL;
}
@@ -1201,13 +1265,22 @@ static int __bpf_async_init(struct bpf_async_kern *async, struct bpf_map *map, u
goto out;
}
- if (type == BPF_ASYNC_TYPE_TIMER) {
+ switch (type) {
+ case BPF_ASYNC_TYPE_TIMER:
clockid = flags & (MAX_CLOCKS - 1);
t = (struct bpf_hrtimer *)cb;
hrtimer_init(&t->timer, clockid, HRTIMER_MODE_REL_SOFT);
t->timer.function = bpf_timer_cb;
cb->value = (void *)async - map->record->timer_off;
+ break;
+ case BPF_ASYNC_TYPE_WQ:
+ w = (struct bpf_work *)cb;
+
+ INIT_WORK(&w->work, bpf_wq_work);
+ INIT_WORK(&w->delete_work, bpf_wq_delete_work);
+ cb->value = (void *)async - map->record->wq_off;
+ break;
}
cb->map = map;
cb->prog = NULL;
@@ -1473,7 +1546,19 @@ void bpf_timer_cancel_and_free(void *val)
*/
void bpf_wq_cancel_and_free(void *val)
{
+ struct bpf_work *work;
+
BTF_TYPE_EMIT(struct bpf_wq);
+
+ work = (struct bpf_work *)__bpf_async_cancel_and_free(val);
+ if (!work)
+ return;
+ /* Trigger cancel of the sleepable work, but *do not* wait for
+ * it to finish if it was running as we might not be in a
+ * sleepable context.
+ * kfree will be called once the work has finished.
+ */
+ schedule_work(&work->delete_work);
}
BPF_CALL_2(bpf_kptr_xchg, void *, map_value, void *, ptr)
@@ -2612,6 +2697,20 @@ __bpf_kfunc void bpf_throw(u64 cookie)
WARN(1, "A call to BPF exception callback should never return\n");
}
+__bpf_kfunc int bpf_wq_init(struct bpf_wq *wq, void *p__map, unsigned int flags)
+{
+ struct bpf_async_kern *async = (struct bpf_async_kern *)wq;
+ struct bpf_map *map = p__map;
+
+ BUILD_BUG_ON(sizeof(struct bpf_async_kern) > sizeof(struct bpf_wq));
+ BUILD_BUG_ON(__alignof__(struct bpf_async_kern) != __alignof__(struct bpf_wq));
+
+ if (flags)
+ return -EINVAL;
+
+ return __bpf_async_init(async, map, flags, BPF_ASYNC_TYPE_WQ);
+}
+
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(generic_btf_ids)
@@ -2689,6 +2788,7 @@ BTF_ID_FLAGS(func, bpf_dynptr_is_rdonly)
BTF_ID_FLAGS(func, bpf_dynptr_size)
BTF_ID_FLAGS(func, bpf_dynptr_clone)
BTF_ID_FLAGS(func, bpf_modify_return_test_tp)
+BTF_ID_FLAGS(func, bpf_wq_init)
BTF_KFUNCS_END(common_btf_ids)
static const struct btf_kfunc_id_set common_kfunc_set = {