1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2019 Facebook */
3 #include <linux/hash.h>
5 #include <linux/filter.h>
6 #include <linux/ftrace.h>
7 #include <linux/rbtree_latch.h>
8 #include <linux/perf_event.h>
10 #include <linux/rcupdate_trace.h>
11 #include <linux/rcupdate_wait.h>
12 #include <linux/static_call.h>
13 #include <linux/bpf_verifier.h>
14 #include <linux/bpf_lsm.h>
15 #include <linux/delay.h>
17 /* dummy _ops. The verifier will operate on target program's ops. */
18 const struct bpf_verifier_ops bpf_extension_verifier_ops = {
20 const struct bpf_prog_ops bpf_extension_prog_ops = {
23 /* btf_vmlinux has ~22k attachable functions. 1k htab is enough. */
24 #define TRAMPOLINE_HASH_BITS 10
25 #define TRAMPOLINE_TABLE_SIZE (1 << TRAMPOLINE_HASH_BITS)
27 static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE];
29 /* serializes access to trampoline_table */
30 static DEFINE_MUTEX(trampoline_mutex);
32 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
33 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex);
35 static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd)
37 struct bpf_trampoline *tr = ops->private;
40 if (cmd == FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF) {
41 /* This is called inside register_ftrace_direct_multi(), so
42 * tr->mutex is already locked.
44 lockdep_assert_held_once(&tr->mutex);
46 /* Instead of updating the trampoline here, we propagate
47 * -EAGAIN to register_ftrace_direct(). Then we can
48 * retry register_ftrace_direct() after updating the
51 if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) &&
52 !(tr->flags & BPF_TRAMP_F_ORIG_STACK)) {
53 if (WARN_ON_ONCE(tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY))
56 tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY;
63 /* The normal locking order is
64 * tr->mutex => direct_mutex (ftrace.c) => ftrace_lock (ftrace.c)
66 * The following two commands are called from
68 * prepare_direct_functions_for_ipmodify
69 * cleanup_direct_functions_after_ipmodify
71 * In both cases, direct_mutex is already locked. Use
72 * mutex_trylock(&tr->mutex) to avoid deadlock in race condition
73 * (something else is making changes to this same trampoline).
75 if (!mutex_trylock(&tr->mutex)) {
76 /* sleep 1 ms to make sure whatever holding tr->mutex makes
84 case FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER:
85 tr->flags |= BPF_TRAMP_F_SHARE_IPMODIFY;
87 if ((tr->flags & BPF_TRAMP_F_CALL_ORIG) &&
88 !(tr->flags & BPF_TRAMP_F_ORIG_STACK))
89 ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */);
91 case FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER:
92 tr->flags &= ~BPF_TRAMP_F_SHARE_IPMODIFY;
94 if (tr->flags & BPF_TRAMP_F_ORIG_STACK)
95 ret = bpf_trampoline_update(tr, false /* lock_direct_mutex */);
102 mutex_unlock(&tr->mutex);
107 bool bpf_prog_has_trampoline(const struct bpf_prog *prog)
109 enum bpf_attach_type eatype = prog->expected_attach_type;
110 enum bpf_prog_type ptype = prog->type;
112 return (ptype == BPF_PROG_TYPE_TRACING &&
113 (eatype == BPF_TRACE_FENTRY || eatype == BPF_TRACE_FEXIT ||
114 eatype == BPF_MODIFY_RETURN)) ||
115 (ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC);
118 void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym)
120 ksym->start = (unsigned long) data;
121 ksym->end = ksym->start + PAGE_SIZE;
123 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start,
124 PAGE_SIZE, false, ksym->name);
127 void bpf_image_ksym_del(struct bpf_ksym *ksym)
130 perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, ksym->start,
131 PAGE_SIZE, true, ksym->name);
134 static struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
136 struct bpf_trampoline *tr;
137 struct hlist_head *head;
140 mutex_lock(&trampoline_mutex);
141 head = &trampoline_table[hash_64(key, TRAMPOLINE_HASH_BITS)];
142 hlist_for_each_entry(tr, head, hlist) {
143 if (tr->key == key) {
144 refcount_inc(&tr->refcnt);
148 tr = kzalloc(sizeof(*tr), GFP_KERNEL);
151 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
152 tr->fops = kzalloc(sizeof(struct ftrace_ops), GFP_KERNEL);
158 tr->fops->private = tr;
159 tr->fops->ops_func = bpf_tramp_ftrace_ops_func;
163 INIT_HLIST_NODE(&tr->hlist);
164 hlist_add_head(&tr->hlist, head);
165 refcount_set(&tr->refcnt, 1);
166 mutex_init(&tr->mutex);
167 for (i = 0; i < BPF_TRAMP_MAX; i++)
168 INIT_HLIST_HEAD(&tr->progs_hlist[i]);
170 mutex_unlock(&trampoline_mutex);
174 static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr)
176 void *ip = tr->func.addr;
179 if (tr->func.ftrace_managed)
180 ret = unregister_ftrace_direct(tr->fops, (long)old_addr, false);
182 ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL);
187 static int modify_fentry(struct bpf_trampoline *tr, void *old_addr, void *new_addr,
188 bool lock_direct_mutex)
190 void *ip = tr->func.addr;
193 if (tr->func.ftrace_managed) {
194 if (lock_direct_mutex)
195 ret = modify_ftrace_direct(tr->fops, (long)new_addr);
197 ret = modify_ftrace_direct_nolock(tr->fops, (long)new_addr);
199 ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, new_addr);
204 /* first time registering */
205 static int register_fentry(struct bpf_trampoline *tr, void *new_addr)
207 void *ip = tr->func.addr;
211 faddr = ftrace_location((unsigned long)ip);
215 tr->func.ftrace_managed = true;
218 if (tr->func.ftrace_managed) {
219 ftrace_set_filter_ip(tr->fops, (unsigned long)ip, 0, 1);
220 ret = register_ftrace_direct(tr->fops, (long)new_addr);
222 ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, NULL, new_addr);
228 static struct bpf_tramp_links *
229 bpf_trampoline_get_progs(const struct bpf_trampoline *tr, int *total, bool *ip_arg)
231 struct bpf_tramp_link *link;
232 struct bpf_tramp_links *tlinks;
233 struct bpf_tramp_link **links;
237 tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL);
239 return ERR_PTR(-ENOMEM);
241 for (kind = 0; kind < BPF_TRAMP_MAX; kind++) {
242 tlinks[kind].nr_links = tr->progs_cnt[kind];
243 *total += tr->progs_cnt[kind];
244 links = tlinks[kind].links;
246 hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) {
247 *ip_arg |= link->link.prog->call_get_func_ip;
254 static void bpf_tramp_image_free(struct bpf_tramp_image *im)
256 bpf_image_ksym_del(&im->ksym);
257 bpf_jit_free_exec(im->image);
258 bpf_jit_uncharge_modmem(PAGE_SIZE);
259 percpu_ref_exit(&im->pcref);
263 static void __bpf_tramp_image_put_deferred(struct work_struct *work)
265 struct bpf_tramp_image *im;
267 im = container_of(work, struct bpf_tramp_image, work);
268 bpf_tramp_image_free(im);
271 /* callback, fexit step 3 or fentry step 2 */
272 static void __bpf_tramp_image_put_rcu(struct rcu_head *rcu)
274 struct bpf_tramp_image *im;
276 im = container_of(rcu, struct bpf_tramp_image, rcu);
277 INIT_WORK(&im->work, __bpf_tramp_image_put_deferred);
278 schedule_work(&im->work);
281 /* callback, fexit step 2. Called after percpu_ref_kill confirms. */
282 static void __bpf_tramp_image_release(struct percpu_ref *pcref)
284 struct bpf_tramp_image *im;
286 im = container_of(pcref, struct bpf_tramp_image, pcref);
287 call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu);
290 /* callback, fexit or fentry step 1 */
291 static void __bpf_tramp_image_put_rcu_tasks(struct rcu_head *rcu)
293 struct bpf_tramp_image *im;
295 im = container_of(rcu, struct bpf_tramp_image, rcu);
296 if (im->ip_after_call)
297 /* the case of fmod_ret/fexit trampoline and CONFIG_PREEMPTION=y */
298 percpu_ref_kill(&im->pcref);
300 /* the case of fentry trampoline */
301 call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu);
304 static void bpf_tramp_image_put(struct bpf_tramp_image *im)
306 /* The trampoline image that calls original function is using:
307 * rcu_read_lock_trace to protect sleepable bpf progs
308 * rcu_read_lock to protect normal bpf progs
309 * percpu_ref to protect trampoline itself
310 * rcu tasks to protect trampoline asm not covered by percpu_ref
311 * (which are few asm insns before __bpf_tramp_enter and
312 * after __bpf_tramp_exit)
314 * The trampoline is unreachable before bpf_tramp_image_put().
316 * First, patch the trampoline to avoid calling into fexit progs.
317 * The progs will be freed even if the original function is still
318 * executing or sleeping.
319 * In case of CONFIG_PREEMPT=y use call_rcu_tasks() to wait on
320 * first few asm instructions to execute and call into
321 * __bpf_tramp_enter->percpu_ref_get.
322 * Then use percpu_ref_kill to wait for the trampoline and the original
323 * function to finish.
324 * Then use call_rcu_tasks() to make sure few asm insns in
325 * the trampoline epilogue are done as well.
327 * In !PREEMPT case the task that got interrupted in the first asm
328 * insns won't go through an RCU quiescent state which the
329 * percpu_ref_kill will be waiting for. Hence the first
330 * call_rcu_tasks() is not necessary.
332 if (im->ip_after_call) {
333 int err = bpf_arch_text_poke(im->ip_after_call, BPF_MOD_JUMP,
334 NULL, im->ip_epilogue);
336 if (IS_ENABLED(CONFIG_PREEMPTION))
337 call_rcu_tasks(&im->rcu, __bpf_tramp_image_put_rcu_tasks);
339 percpu_ref_kill(&im->pcref);
343 /* The trampoline without fexit and fmod_ret progs doesn't call original
344 * function and doesn't use percpu_ref.
345 * Use call_rcu_tasks_trace() to wait for sleepable progs to finish.
346 * Then use call_rcu_tasks() to wait for the rest of trampoline asm
349 call_rcu_tasks_trace(&im->rcu, __bpf_tramp_image_put_rcu_tasks);
352 static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key)
354 struct bpf_tramp_image *im;
355 struct bpf_ksym *ksym;
359 im = kzalloc(sizeof(*im), GFP_KERNEL);
363 err = bpf_jit_charge_modmem(PAGE_SIZE);
368 im->image = image = bpf_jit_alloc_exec(PAGE_SIZE);
371 set_vm_flush_reset_perms(image);
373 err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL);
378 INIT_LIST_HEAD_RCU(&ksym->lnode);
379 snprintf(ksym->name, KSYM_NAME_LEN, "bpf_trampoline_%llu", key);
380 bpf_image_ksym_add(image, ksym);
384 bpf_jit_free_exec(im->image);
386 bpf_jit_uncharge_modmem(PAGE_SIZE);
393 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex)
395 struct bpf_tramp_image *im;
396 struct bpf_tramp_links *tlinks;
397 u32 orig_flags = tr->flags;
401 tlinks = bpf_trampoline_get_progs(tr, &total, &ip_arg);
403 return PTR_ERR(tlinks);
406 err = unregister_fentry(tr, tr->cur_image->image);
407 bpf_tramp_image_put(tr->cur_image);
408 tr->cur_image = NULL;
412 im = bpf_tramp_image_alloc(tr->key);
418 /* clear all bits except SHARE_IPMODIFY and TAIL_CALL_CTX */
419 tr->flags &= (BPF_TRAMP_F_SHARE_IPMODIFY | BPF_TRAMP_F_TAIL_CALL_CTX);
421 if (tlinks[BPF_TRAMP_FEXIT].nr_links ||
422 tlinks[BPF_TRAMP_MODIFY_RETURN].nr_links) {
423 /* NOTE: BPF_TRAMP_F_RESTORE_REGS and BPF_TRAMP_F_SKIP_FRAME
424 * should not be set together.
426 tr->flags |= BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_SKIP_FRAME;
428 tr->flags |= BPF_TRAMP_F_RESTORE_REGS;
432 tr->flags |= BPF_TRAMP_F_IP_ARG;
434 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
436 if ((tr->flags & BPF_TRAMP_F_SHARE_IPMODIFY) &&
437 (tr->flags & BPF_TRAMP_F_CALL_ORIG))
438 tr->flags |= BPF_TRAMP_F_ORIG_STACK;
441 err = arch_prepare_bpf_trampoline(im, im->image, im->image + PAGE_SIZE,
442 &tr->func.model, tr->flags, tlinks,
447 set_memory_rox((long)im->image, 1);
449 WARN_ON(tr->cur_image && total == 0);
451 /* progs already running at this address */
452 err = modify_fentry(tr, tr->cur_image->image, im->image, lock_direct_mutex);
454 /* first time registering */
455 err = register_fentry(tr, im->image);
457 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
458 if (err == -EAGAIN) {
459 /* -EAGAIN from bpf_tramp_ftrace_ops_func. Now
460 * BPF_TRAMP_F_SHARE_IPMODIFY is set, we can generate the
461 * trampoline again, and retry register.
463 /* reset fops->func and fops->trampoline for re-register */
464 tr->fops->func = NULL;
465 tr->fops->trampoline = 0;
467 /* reset im->image memory attr for arch_prepare_bpf_trampoline */
468 set_memory_nx((long)im->image, 1);
469 set_memory_rw((long)im->image, 1);
477 bpf_tramp_image_put(tr->cur_image);
480 /* If any error happens, restore previous flags */
482 tr->flags = orig_flags;
487 bpf_tramp_image_free(im);
491 static enum bpf_tramp_prog_type bpf_attach_type_to_tramp(struct bpf_prog *prog)
493 switch (prog->expected_attach_type) {
494 case BPF_TRACE_FENTRY:
495 return BPF_TRAMP_FENTRY;
496 case BPF_MODIFY_RETURN:
497 return BPF_TRAMP_MODIFY_RETURN;
498 case BPF_TRACE_FEXIT:
499 return BPF_TRAMP_FEXIT;
501 if (!prog->aux->attach_func_proto->type)
502 /* The function returns void, we cannot modify its
505 return BPF_TRAMP_FEXIT;
507 return BPF_TRAMP_MODIFY_RETURN;
509 return BPF_TRAMP_REPLACE;
513 static int __bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
515 enum bpf_tramp_prog_type kind;
516 struct bpf_tramp_link *link_exiting;
520 kind = bpf_attach_type_to_tramp(link->link.prog);
521 if (tr->extension_prog)
522 /* cannot attach fentry/fexit if extension prog is attached.
523 * cannot overwrite extension prog either.
527 for (i = 0; i < BPF_TRAMP_MAX; i++)
528 cnt += tr->progs_cnt[i];
530 if (kind == BPF_TRAMP_REPLACE) {
531 /* Cannot attach extension if fentry/fexit are in use. */
534 tr->extension_prog = link->link.prog;
535 return bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP, NULL,
536 link->link.prog->bpf_func);
538 if (cnt >= BPF_MAX_TRAMP_LINKS)
540 if (!hlist_unhashed(&link->tramp_hlist))
541 /* prog already linked */
543 hlist_for_each_entry(link_exiting, &tr->progs_hlist[kind], tramp_hlist) {
544 if (link_exiting->link.prog != link->link.prog)
546 /* prog already linked */
550 hlist_add_head(&link->tramp_hlist, &tr->progs_hlist[kind]);
551 tr->progs_cnt[kind]++;
552 err = bpf_trampoline_update(tr, true /* lock_direct_mutex */);
554 hlist_del_init(&link->tramp_hlist);
555 tr->progs_cnt[kind]--;
560 int bpf_trampoline_link_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
564 mutex_lock(&tr->mutex);
565 err = __bpf_trampoline_link_prog(link, tr);
566 mutex_unlock(&tr->mutex);
570 static int __bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
572 enum bpf_tramp_prog_type kind;
575 kind = bpf_attach_type_to_tramp(link->link.prog);
576 if (kind == BPF_TRAMP_REPLACE) {
577 WARN_ON_ONCE(!tr->extension_prog);
578 err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
579 tr->extension_prog->bpf_func, NULL);
580 tr->extension_prog = NULL;
583 hlist_del_init(&link->tramp_hlist);
584 tr->progs_cnt[kind]--;
585 return bpf_trampoline_update(tr, true /* lock_direct_mutex */);
588 /* bpf_trampoline_unlink_prog() should never fail. */
589 int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampoline *tr)
593 mutex_lock(&tr->mutex);
594 err = __bpf_trampoline_unlink_prog(link, tr);
595 mutex_unlock(&tr->mutex);
599 #if defined(CONFIG_CGROUP_BPF) && defined(CONFIG_BPF_LSM)
600 static void bpf_shim_tramp_link_release(struct bpf_link *link)
602 struct bpf_shim_tramp_link *shim_link =
603 container_of(link, struct bpf_shim_tramp_link, link.link);
605 /* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */
606 if (!shim_link->trampoline)
609 WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline));
610 bpf_trampoline_put(shim_link->trampoline);
613 static void bpf_shim_tramp_link_dealloc(struct bpf_link *link)
615 struct bpf_shim_tramp_link *shim_link =
616 container_of(link, struct bpf_shim_tramp_link, link.link);
621 static const struct bpf_link_ops bpf_shim_tramp_link_lops = {
622 .release = bpf_shim_tramp_link_release,
623 .dealloc = bpf_shim_tramp_link_dealloc,
626 static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog,
630 struct bpf_shim_tramp_link *shim_link = NULL;
633 shim_link = kzalloc(sizeof(*shim_link), GFP_USER);
637 p = bpf_prog_alloc(1, 0);
644 p->bpf_func = bpf_func;
646 p->aux->cgroup_atype = cgroup_atype;
647 p->aux->attach_func_proto = prog->aux->attach_func_proto;
648 p->aux->attach_btf_id = prog->aux->attach_btf_id;
649 p->aux->attach_btf = prog->aux->attach_btf;
650 btf_get(p->aux->attach_btf);
651 p->type = BPF_PROG_TYPE_LSM;
652 p->expected_attach_type = BPF_LSM_MAC;
654 bpf_link_init(&shim_link->link.link, BPF_LINK_TYPE_UNSPEC,
655 &bpf_shim_tramp_link_lops, p);
656 bpf_cgroup_atype_get(p->aux->attach_btf_id, cgroup_atype);
661 static struct bpf_shim_tramp_link *cgroup_shim_find(struct bpf_trampoline *tr,
664 struct bpf_tramp_link *link;
667 for (kind = 0; kind < BPF_TRAMP_MAX; kind++) {
668 hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) {
669 struct bpf_prog *p = link->link.prog;
671 if (p->bpf_func == bpf_func)
672 return container_of(link, struct bpf_shim_tramp_link, link);
679 int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog,
682 struct bpf_shim_tramp_link *shim_link = NULL;
683 struct bpf_attach_target_info tgt_info = {};
684 struct bpf_trampoline *tr;
689 err = bpf_check_attach_target(NULL, prog, NULL,
690 prog->aux->attach_btf_id,
695 key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf,
696 prog->aux->attach_btf_id);
698 bpf_lsm_find_cgroup_shim(prog, &bpf_func);
699 tr = bpf_trampoline_get(key, &tgt_info);
703 mutex_lock(&tr->mutex);
705 shim_link = cgroup_shim_find(tr, bpf_func);
707 /* Reusing existing shim attached by the other program. */
708 bpf_link_inc(&shim_link->link.link);
710 mutex_unlock(&tr->mutex);
711 bpf_trampoline_put(tr); /* bpf_trampoline_get above */
715 /* Allocate and install new shim. */
717 shim_link = cgroup_shim_alloc(prog, bpf_func, cgroup_atype);
723 err = __bpf_trampoline_link_prog(&shim_link->link, tr);
727 shim_link->trampoline = tr;
728 /* note, we're still holding tr refcnt from above */
730 mutex_unlock(&tr->mutex);
734 mutex_unlock(&tr->mutex);
737 bpf_link_put(&shim_link->link.link);
739 /* have to release tr while _not_ holding its mutex */
740 bpf_trampoline_put(tr); /* bpf_trampoline_get above */
745 void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog)
747 struct bpf_shim_tramp_link *shim_link = NULL;
748 struct bpf_trampoline *tr;
752 key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf,
753 prog->aux->attach_btf_id);
755 bpf_lsm_find_cgroup_shim(prog, &bpf_func);
756 tr = bpf_trampoline_lookup(key);
757 if (WARN_ON_ONCE(!tr))
760 mutex_lock(&tr->mutex);
761 shim_link = cgroup_shim_find(tr, bpf_func);
762 mutex_unlock(&tr->mutex);
765 bpf_link_put(&shim_link->link.link);
767 bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */
771 struct bpf_trampoline *bpf_trampoline_get(u64 key,
772 struct bpf_attach_target_info *tgt_info)
774 struct bpf_trampoline *tr;
776 tr = bpf_trampoline_lookup(key);
780 mutex_lock(&tr->mutex);
784 memcpy(&tr->func.model, &tgt_info->fmodel, sizeof(tgt_info->fmodel));
785 tr->func.addr = (void *)tgt_info->tgt_addr;
787 mutex_unlock(&tr->mutex);
791 void bpf_trampoline_put(struct bpf_trampoline *tr)
797 mutex_lock(&trampoline_mutex);
798 if (!refcount_dec_and_test(&tr->refcnt))
800 WARN_ON_ONCE(mutex_is_locked(&tr->mutex));
802 for (i = 0; i < BPF_TRAMP_MAX; i++)
803 if (WARN_ON_ONCE(!hlist_empty(&tr->progs_hlist[i])))
806 /* This code will be executed even when the last bpf_tramp_image
807 * is alive. All progs are detached from the trampoline and the
808 * trampoline image is patched with jmp into epilogue to skip
809 * fexit progs. The fentry-only trampoline will be freed via
810 * multiple rcu callbacks.
812 hlist_del(&tr->hlist);
814 ftrace_free_filter(tr->fops);
819 mutex_unlock(&trampoline_mutex);
822 #define NO_START_TIME 1
823 static __always_inline u64 notrace bpf_prog_start_time(void)
825 u64 start = NO_START_TIME;
827 if (static_branch_unlikely(&bpf_stats_enabled_key)) {
828 start = sched_clock();
829 if (unlikely(!start))
830 start = NO_START_TIME;
835 /* The logic is similar to bpf_prog_run(), but with an explicit
836 * rcu_read_lock() and migrate_disable() which are required
837 * for the trampoline. The macro is split into
838 * call __bpf_prog_enter
839 * call prog->bpf_func
840 * call __bpf_prog_exit
842 * __bpf_prog_enter returns:
843 * 0 - skip execution of the bpf prog
844 * 1 - execute bpf prog
845 * [2..MAX_U64] - execute bpf prog and record execution time.
846 * This is start time.
848 static u64 notrace __bpf_prog_enter_recur(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx)
854 run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
856 if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
857 bpf_prog_inc_misses_counter(prog);
860 return bpf_prog_start_time();
863 static void notrace update_prog_stats(struct bpf_prog *prog,
866 struct bpf_prog_stats *stats;
868 if (static_branch_unlikely(&bpf_stats_enabled_key) &&
869 /* static_key could be enabled in __bpf_prog_enter*
870 * and disabled in __bpf_prog_exit*.
872 * Hence check that 'start' is valid.
874 start > NO_START_TIME) {
877 stats = this_cpu_ptr(prog->stats);
878 flags = u64_stats_update_begin_irqsave(&stats->syncp);
879 u64_stats_inc(&stats->cnt);
880 u64_stats_add(&stats->nsecs, sched_clock() - start);
881 u64_stats_update_end_irqrestore(&stats->syncp, flags);
885 static void notrace __bpf_prog_exit_recur(struct bpf_prog *prog, u64 start,
886 struct bpf_tramp_run_ctx *run_ctx)
889 bpf_reset_run_ctx(run_ctx->saved_run_ctx);
891 update_prog_stats(prog, start);
892 this_cpu_dec(*(prog->active));
897 static u64 notrace __bpf_prog_enter_lsm_cgroup(struct bpf_prog *prog,
898 struct bpf_tramp_run_ctx *run_ctx)
901 /* Runtime stats are exported via actual BPF_LSM_CGROUP
902 * programs, not the shims.
907 run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
909 return NO_START_TIME;
912 static void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start,
913 struct bpf_tramp_run_ctx *run_ctx)
916 bpf_reset_run_ctx(run_ctx->saved_run_ctx);
922 u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog,
923 struct bpf_tramp_run_ctx *run_ctx)
925 rcu_read_lock_trace();
929 run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
931 if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) {
932 bpf_prog_inc_misses_counter(prog);
935 return bpf_prog_start_time();
938 void notrace __bpf_prog_exit_sleepable_recur(struct bpf_prog *prog, u64 start,
939 struct bpf_tramp_run_ctx *run_ctx)
941 bpf_reset_run_ctx(run_ctx->saved_run_ctx);
943 update_prog_stats(prog, start);
944 this_cpu_dec(*(prog->active));
946 rcu_read_unlock_trace();
949 static u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog,
950 struct bpf_tramp_run_ctx *run_ctx)
952 rcu_read_lock_trace();
956 run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
958 return bpf_prog_start_time();
961 static void notrace __bpf_prog_exit_sleepable(struct bpf_prog *prog, u64 start,
962 struct bpf_tramp_run_ctx *run_ctx)
964 bpf_reset_run_ctx(run_ctx->saved_run_ctx);
966 update_prog_stats(prog, start);
968 rcu_read_unlock_trace();
971 static u64 notrace __bpf_prog_enter(struct bpf_prog *prog,
972 struct bpf_tramp_run_ctx *run_ctx)
978 run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx);
980 return bpf_prog_start_time();
983 static void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start,
984 struct bpf_tramp_run_ctx *run_ctx)
987 bpf_reset_run_ctx(run_ctx->saved_run_ctx);
989 update_prog_stats(prog, start);
994 void notrace __bpf_tramp_enter(struct bpf_tramp_image *tr)
996 percpu_ref_get(&tr->pcref);
999 void notrace __bpf_tramp_exit(struct bpf_tramp_image *tr)
1001 percpu_ref_put(&tr->pcref);
1004 bpf_trampoline_enter_t bpf_trampoline_enter(const struct bpf_prog *prog)
1006 bool sleepable = prog->aux->sleepable;
1008 if (bpf_prog_check_recur(prog))
1009 return sleepable ? __bpf_prog_enter_sleepable_recur :
1010 __bpf_prog_enter_recur;
1012 if (resolve_prog_type(prog) == BPF_PROG_TYPE_LSM &&
1013 prog->expected_attach_type == BPF_LSM_CGROUP)
1014 return __bpf_prog_enter_lsm_cgroup;
1016 return sleepable ? __bpf_prog_enter_sleepable : __bpf_prog_enter;
1019 bpf_trampoline_exit_t bpf_trampoline_exit(const struct bpf_prog *prog)
1021 bool sleepable = prog->aux->sleepable;
1023 if (bpf_prog_check_recur(prog))
1024 return sleepable ? __bpf_prog_exit_sleepable_recur :
1025 __bpf_prog_exit_recur;
1027 if (resolve_prog_type(prog) == BPF_PROG_TYPE_LSM &&
1028 prog->expected_attach_type == BPF_LSM_CGROUP)
1029 return __bpf_prog_exit_lsm_cgroup;
1031 return sleepable ? __bpf_prog_exit_sleepable : __bpf_prog_exit;
1035 arch_prepare_bpf_trampoline(struct bpf_tramp_image *tr, void *image, void *image_end,
1036 const struct btf_func_model *m, u32 flags,
1037 struct bpf_tramp_links *tlinks,
1043 static int __init init_trampolines(void)
1047 for (i = 0; i < TRAMPOLINE_TABLE_SIZE; i++)
1048 INIT_HLIST_HEAD(&trampoline_table[i]);
1051 late_initcall(init_trampolines);