bpf: Add BPF_TRAMPOLINE_BATCH_DETACH support

4 files changed, 46 insertions, 13 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d28c7ac3af3f4..828a4e88224f0 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -653,7 +653,8 @@ static __always_inline unsigned int bpf_dispatcher_nop_func(
 #ifdef CONFIG_BPF_JIT
 int bpf_trampoline_link_prog(struct bpf_prog *prog, struct bpf_trampoline *tr,
 			     struct bpf_trampoline_batch *batch);
-int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr);
+int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr,
+			       struct bpf_trampoline_batch *batch);
 struct bpf_trampoline *bpf_trampoline_get(u64 key,
 					  struct bpf_attach_target_info *tgt_info);
 void bpf_trampoline_put(struct bpf_trampoline *tr);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 04df4d576fd43..b6a08aa49aa43 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -126,6 +126,7 @@ enum bpf_cmd {
 	BPF_LINK_DETACH,
 	BPF_PROG_BIND_MAP,
 	BPF_TRAMPOLINE_BATCH_ATTACH,
+	BPF_TRAMPOLINE_BATCH_DETACH,
 };
 
 enum bpf_map_type {
@@ -632,7 +633,7 @@ union bpf_attr {
 		__u32 prog_fd;
 	} raw_tracepoint;
 
-	struct { /* anonymous struct used by BPF_TRAMPOLINE_BATCH_ATTACH */
+	struct { /* anonymous struct used by BPF_TRAMPOLINE_BATCH_* */
 		__aligned_u64	in;
 		__aligned_u64	out;
 		__u32		count;
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 758d211a05672..587f2b2d19c13 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2505,7 +2505,7 @@ static void bpf_tracing_link_release(struct bpf_link *link)
 		container_of(link, struct bpf_tracing_link, link);
 
 	WARN_ON_ONCE(bpf_trampoline_unlink_prog(link->prog,
-						tr_link->trampoline));
+						tr_link->trampoline, NULL));
 
 	bpf_trampoline_put(tr_link->trampoline);
 
@@ -2940,10 +2940,33 @@ static int bpf_trampoline_batch(const union bpf_attr *attr, int cmd)
 				goto out_clean;
 
 			out[i] = fd;
+		} else {
+			struct bpf_tracing_link *tr_link;
+			struct bpf_link *link;
+
+			link = bpf_link_get_from_fd(in[i]);
+			if (IS_ERR(link)) {
+				ret = PTR_ERR(link);
+				goto out_clean;
+			}
+
+			if (link->type != BPF_LINK_TYPE_TRACING) {
+				ret = -EINVAL;
+				bpf_link_put(link);
+				goto out_clean;
+			}
+
+			tr_link = container_of(link, struct bpf_tracing_link, link);
+			bpf_trampoline_unlink_prog(link->prog, tr_link->trampoline, batch);
+			bpf_link_put(link);
 		}
 	}
 
-	ret = register_ftrace_direct_ips(batch->ips, batch->addrs, batch->idx);
+	if (cmd == BPF_TRAMPOLINE_BATCH_ATTACH)
+		ret = register_ftrace_direct_ips(batch->ips, batch->addrs, batch->idx);
+	else
+		ret = unregister_ftrace_direct_ips(batch->ips, batch->addrs, batch->idx);
+
 	if (!ret)
 		WARN_ON_ONCE(copy_to_user(uout, out, count * sizeof(u32)));
 
@@ -4514,6 +4537,7 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
 		err = bpf_raw_tracepoint_open(&attr);
 		break;
 	case BPF_TRAMPOLINE_BATCH_ATTACH:
+	case BPF_TRAMPOLINE_BATCH_DETACH:
 		err = bpf_trampoline_batch(&attr, cmd);
 		break;
 	case BPF_BTF_LOAD:
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index ba2ba28a56c96..14d093610ed11 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -164,14 +164,18 @@ static int is_ftrace_location(void *ip)
 	return 1;
 }
 
-static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr)
+static int unregister_fentry(struct bpf_trampoline *tr, void *old_addr,
+			     struct bpf_trampoline_batch *batch)
 {
 	void *ip = tr->func.addr;
 	int ret;
 
-	if (tr->func.ftrace_managed)
-		ret = unregister_ftrace_direct((long)ip, (long)old_addr);
-	else
+	if (tr->func.ftrace_managed) {
+		if (batch)
+			ret = bpf_trampoline_batch_add(batch, (long)ip, (long)old_addr);
+		else
+			ret = unregister_ftrace_direct((long)ip, (long)old_addr);
+	} else
 		ret = bpf_arch_text_poke(ip, BPF_MOD_CALL, old_addr, NULL);
 	return ret;
 }
@@ -248,7 +252,7 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr,
 		return PTR_ERR(tprogs);
 
 	if (total == 0) {
-		err = unregister_fentry(tr, old_image);
+		err = unregister_fentry(tr, old_image, batch);
 		tr->selector = 0;
 		goto out;
 	}
@@ -361,13 +365,16 @@ out:
 }
 
 /* bpf_trampoline_unlink_prog() should never fail. */
-int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
+int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr,
+			       struct bpf_trampoline_batch *batch)
 {
 	enum bpf_tramp_prog_type kind;
-	int err;
+	int err = 0;
 
 	kind = bpf_attach_type_to_tramp(prog);
 	mutex_lock(&tr->mutex);
+	if (hlist_unhashed(&prog->aux->tramp_hlist))
+		goto out;
 	if (kind == BPF_TRAMP_REPLACE) {
 		WARN_ON_ONCE(!tr->extension_prog);
 		err = bpf_arch_text_poke(tr->func.addr, BPF_MOD_JUMP,
@@ -375,9 +382,9 @@ int bpf_trampoline_unlink_prog(struct bpf_prog *prog, struct bpf_trampoline *tr)
 		tr->extension_prog = NULL;
 		goto out;
 	}
-	hlist_del(&prog->aux->tramp_hlist);
+	hlist_del_init(&prog->aux->tramp_hlist);
 	tr->progs_cnt[kind]--;
-	err = bpf_trampoline_update(tr, NULL);
+	err = bpf_trampoline_update(tr, batch);
 out:
 	mutex_unlock(&tr->mutex);
 	return err;