diff mbox series

[RFC,bpf-next,1/3] bpf: introduce trace option to the BPF_PROG_TEST_RUN command API

Message ID 158453677145.3043.1585141550260881967.stgit@xdp-tutorial
State RFC
Delegated to: BPF Maintainers
Headers show
Series bpf: add tracing for XDP programs using the BPF_PROG_TEST_RUN API | expand

Commit Message

Eelco Chaudron March 18, 2020, 1:06 p.m. UTC 
This patch adds a flag to the existing BPF_PROG_TEST_RUN API,
which will allow tracing for XDP programs.

Signed-off-by: Eelco Chaudron <echaudro@redhat.com>
---
 include/linux/filter.h         |   13 +++++++++++++
 include/uapi/linux/bpf.h       |    4 ++++
 kernel/bpf/syscall.c           |    2 +-
 net/bpf/test_run.c             |   17 +++++++++++------
 tools/include/uapi/linux/bpf.h |    4 ++++
 5 files changed, 33 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 43b5e455d2f5..f95f9ad45ad6 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -737,6 +737,19 @@  static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
 			      BPF_DISPATCHER_FUNC(bpf_dispatcher_xdp));
 }
 
+static __always_inline u32 bpf_prog_run_xdp_trace(const struct bpf_prog *prog,
+						  struct xdp_buff *xdp)
+{
+	/* Caller needs to hold rcu_read_lock() (!), otherwise program
+	 * can be released while still running, or map elements could be
+	 * freed early while still having concurrent users. XDP fastpath
+	 * already takes rcu_read_lock() when fetching the program, so
+	 * it's not necessary here anymore.
+	 */
+	return __BPF_PROG_RUN(prog, xdp,
+			      BPF_DISPATCHER_FUNC(bpf_dispatcher_xdp));
+}
+
 void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog *prog);
 
 static inline u32 bpf_prog_insn_size(const struct bpf_prog *prog)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 40b2d9476268..ac5c89903550 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -375,6 +375,9 @@  enum {
  */
 #define BPF_F_QUERY_EFFECTIVE	(1U << 0)
 
+/* Flags for BPF_PROG_TEST_RUN. */
+#define BPF_F_TEST_ENABLE_TRACE (1U << 0)
+
 enum bpf_stack_build_id_status {
 	/* user space need an empty entry to identify end of a trace */
 	BPF_STACK_BUILD_ID_EMPTY = 0,
@@ -511,6 +514,7 @@  union bpf_attr {
 						 */
 		__aligned_u64	ctx_in;
 		__aligned_u64	ctx_out;
+		__u32           flags;
 	} test;
 
 	struct { /* anonymous struct used by BPF_*_GET_*_ID */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 7ce0815793dd..9a6fae428976 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2680,7 +2680,7 @@  static int bpf_prog_query(const union bpf_attr *attr,
 	return cgroup_bpf_prog_query(attr, uattr);
 }
 
-#define BPF_PROG_TEST_RUN_LAST_FIELD test.ctx_out
+#define BPF_PROG_TEST_RUN_LAST_FIELD test.flags
 
 static int bpf_prog_test_run(const union bpf_attr *attr,
 			     union bpf_attr __user *uattr)
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 4c921f5154e0..061cad840b05 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -16,7 +16,7 @@ 
 #include <trace/events/bpf_test_run.h>
 
 static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
-			u32 *retval, u32 *time, bool xdp)
+			u32 *retval, u32 *time, bool xdp, bool trace)
 {
 	struct bpf_cgroup_storage *storage[MAX_BPF_CGROUP_STORAGE_TYPE] = { NULL };
 	enum bpf_cgroup_storage_type stype;
@@ -43,10 +43,14 @@  static int bpf_test_run(struct bpf_prog *prog, void *ctx, u32 repeat,
 	for (i = 0; i < repeat; i++) {
 		bpf_cgroup_storage_set(storage);
 
-		if (xdp)
-			*retval = bpf_prog_run_xdp(prog, ctx);
-		else
+		if (xdp) {
+			if (trace)
+				*retval = bpf_prog_run_xdp_trace(prog, ctx);
+			else
+				*retval = bpf_prog_run_xdp(prog, ctx);
+		} else {
 			*retval = BPF_PROG_RUN(prog, ctx);
+		}
 
 		if (signal_pending(current)) {
 			ret = -EINTR;
@@ -431,7 +435,7 @@  int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	ret = convert___skb_to_skb(skb, ctx);
 	if (ret)
 		goto out;
-	ret = bpf_test_run(prog, skb, repeat, &retval, &duration, false);
+	ret = bpf_test_run(prog, skb, repeat, &retval, &duration, false, false);
 	if (ret)
 		goto out;
 	if (!is_l2) {
@@ -468,6 +472,7 @@  int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 {
 	u32 size = kattr->test.data_size_in;
 	u32 repeat = kattr->test.repeat;
+	bool trace = kattr->test.flags & BPF_F_TEST_ENABLE_TRACE;
 	struct netdev_rx_queue *rxqueue;
 	struct xdp_buff xdp = {};
 	u32 retval, duration;
@@ -489,7 +494,7 @@  int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 	rxqueue = __netif_get_rx_queue(current->nsproxy->net_ns->loopback_dev, 0);
 	xdp.rxq = &rxqueue->xdp_rxq;
 	bpf_prog_change_xdp(NULL, prog);
-	ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true);
+	ret = bpf_test_run(prog, &xdp, repeat, &retval, &duration, true, trace);
 	if (ret)
 		goto out;
 	if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN ||
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 40b2d9476268..ac5c89903550 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -375,6 +375,9 @@  enum {
  */
 #define BPF_F_QUERY_EFFECTIVE	(1U << 0)
 
+/* Flags for BPF_PROG_TEST_RUN. */
+#define BPF_F_TEST_ENABLE_TRACE (1U << 0)
+
 enum bpf_stack_build_id_status {
 	/* user space need an empty entry to identify end of a trace */
 	BPF_STACK_BUILD_ID_EMPTY = 0,
@@ -511,6 +514,7 @@  union bpf_attr {
 						 */
 		__aligned_u64	ctx_in;
 		__aligned_u64	ctx_out;
+		__u32           flags;
 	} test;
 
 	struct { /* anonymous struct used by BPF_*_GET_*_ID */