BPF: Add sample code for new ib_umad tracepoint

Provide a count of class types for a summary of MAD packets.  The example
shows one way to filter the trace data based on management class.

Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

1 files changed, 144 insertions, 0 deletions

diff --git a/samples/bpf/ibumad_kern.c b/samples/bpf/ibumad_kern.c
new file mode 100644
index 000000000000..38b2b3f22049
--- /dev/null
+++ b/samples/bpf/ibumad_kern.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+
+/**
+ * ibumad BPF sample kernel side
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * Copyright(c) 2018 Ira Weiny, Intel Corporation
+ */
+
+#define KBUILD_MODNAME "ibumad_count_pkts_by_class"
+#include <uapi/linux/bpf.h>
+
+#include "bpf_helpers.h"
+
+
+struct bpf_map_def SEC("maps") read_count = {
+	.type        = BPF_MAP_TYPE_ARRAY,
+	.key_size    = sizeof(u32), /* class; u32 required */
+	.value_size  = sizeof(u64), /* count of mads read */
+	.max_entries = 256, /* Room for all Classes */
+};
+
+struct bpf_map_def SEC("maps") write_count = {
+	.type        = BPF_MAP_TYPE_ARRAY,
+	.key_size    = sizeof(u32), /* class; u32 required */
+	.value_size  = sizeof(u64), /* count of mads written */
+	.max_entries = 256, /* Room for all Classes */
+};
+
+#undef DEBUG
+#ifdef DEBUG
+#define bpf_debug(fmt, ...)                         \
+({                                                  \
+	char ____fmt[] = fmt;                       \
+	bpf_trace_printk(____fmt, sizeof(____fmt),  \
+			 ##__VA_ARGS__);            \
+})
+#else
+#define bpf_debug(fmt, ...)
+#endif
+
+/* Taken from the current format defined in
+ * include/trace/events/ib_umad.h
+ * and
+ * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_read/format
+ * /sys/kernel/debug/tracing/events/ib_umad/ib_umad_write/format
+ */
+struct ib_umad_rw_args {
+	u64 pad;
+	u8 port_num;
+	u8 sl;
+	u8 path_bits;
+	u8 grh_present;
+	u32 id;
+	u32 status;
+	u32 timeout_ms;
+	u32 retires;
+	u32 length;
+	u32 qpn;
+	u32 qkey;
+	u8 gid_index;
+	u8 hop_limit;
+	u16 lid;
+	u16 attr_id;
+	u16 pkey_index;
+	u8 base_version;
+	u8 mgmt_class;
+	u8 class_version;
+	u8 method;
+	u32 flow_label;
+	u16 mad_status;
+	u16 class_specific;
+	u32 attr_mod;
+	u64 tid;
+	u8 gid[16];
+	u32 dev_index;
+	u8 traffic_class;
+};
+
+SEC("tracepoint/ib_umad/ib_umad_read_recv")
+int on_ib_umad_read_recv(struct ib_umad_rw_args *ctx)
+{
+	u64 zero = 0, *val;
+	u8 class = ctx->mgmt_class;
+
+	bpf_debug("ib_umad read recv : class 0x%x\n", class);
+
+	val = bpf_map_lookup_elem(&read_count, &class);
+	if (!val) {
+		bpf_map_update_elem(&read_count, &class, &zero, BPF_NOEXIST);
+		val = bpf_map_lookup_elem(&read_count, &class);
+		if (!val)
+			return 0;
+	}
+
+	(*val) += 1;
+
+	return 0;
+}
+SEC("tracepoint/ib_umad/ib_umad_read_send")
+int on_ib_umad_read_send(struct ib_umad_rw_args *ctx)
+{
+	u64 zero = 0, *val;
+	u8 class = ctx->mgmt_class;
+
+	bpf_debug("ib_umad read send : class 0x%x\n", class);
+
+	val = bpf_map_lookup_elem(&read_count, &class);
+	if (!val) {
+		bpf_map_update_elem(&read_count, &class, &zero, BPF_NOEXIST);
+		val = bpf_map_lookup_elem(&read_count, &class);
+		if (!val)
+			return 0;
+	}
+
+	(*val) += 1;
+
+	return 0;
+}
+SEC("tracepoint/ib_umad/ib_umad_write")
+int on_ib_umad_write(struct ib_umad_rw_args *ctx)
+{
+	u64 zero = 0, *val;
+	u8 class = ctx->mgmt_class;
+
+	bpf_debug("ib_umad write : class 0x%x\n", class);
+
+	val = bpf_map_lookup_elem(&write_count, &class);
+	if (!val) {
+		bpf_map_update_elem(&write_count, &class, &zero, BPF_NOEXIST);
+		val = bpf_map_lookup_elem(&write_count, &class);
+		if (!val)
+			return 0;
+	}
+
+	(*val) += 1;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";