tests verify we get > 0 return value from bpf_trace_print()
using %pT format specifier with various modifiers/pointer
values.
Signed-off-by: Alan Maguire <[email protected]>
---
.../selftests/bpf/prog_tests/trace_printk_btf.c | 83 ++++++++++++++++++++++
.../selftests/bpf/progs/netif_receive_skb.c | 81 +++++++++++++++++++++
2 files changed, 164 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_printk_btf.c
create mode 100644 tools/testing/selftests/bpf/progs/netif_receive_skb.c
diff --git a/tools/testing/selftests/bpf/prog_tests/trace_printk_btf.c b/tools/testing/selftests/bpf/prog_tests/trace_printk_btf.c
new file mode 100644
index 0000000..d7ee158
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/trace_printk_btf.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+struct result {
+ int ret;
+ int subtest;
+ int num_subtest;
+};
+
+/* return value of bpf_trace_printk()s is stored; if nonzero we failed. */
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+ struct result *resp = (struct result *)data;
+
+ *(struct result *)ctx = *resp;
+}
+
+void test_trace_printk_btf(void)
+{
+ struct result res = { 0 };
+ struct bpf_prog_load_attr attr = {
+ .file = "./netif_receive_skb.o",
+ };
+ struct perf_buffer_opts pb_opts = {};
+ struct bpf_program *prog = NULL;
+ struct perf_buffer *pb = NULL;
+ struct bpf_object *obj = NULL;
+ struct bpf_link *link = NULL;
+ struct bpf_map *perf_buf_map;
+ __u32 duration = 0;
+ int err, prog_fd;
+
+ err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+ if (CHECK(err, "prog_load raw tp", "err %d errno %d\n", err, errno))
+ goto close_prog;
+
+ prog = bpf_object__find_program_by_title(obj,
+ "tp_btf/netif_receive_skb");
+ if (CHECK(!prog, "find_prog", "prog netif_receive_skb not found\n"))
+ goto close_prog;
+
+ link = bpf_program__attach_raw_tracepoint(prog, NULL);
+ if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n", PTR_ERR(link)))
+ goto close_prog;
+
+ perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
+ if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
+ goto close_prog;
+
+ /* set up perf buffer */
+ pb_opts.sample_cb = on_sample;
+ pb_opts.ctx = &res;
+ pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
+ if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
+ goto close_prog;
+
+ /* generate receive event */
+ system("ping -c 1 127.0.0.1 >/dev/null");
+
+ /* read perf buffer */
+ err = perf_buffer__poll(pb, 100);
+ if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
+ goto close_prog;
+
+ /*
+ * Make sure netif_receive_skb program was triggered
+ * and it sent expected return values from bpf_trace_printk()s
+ * into ring buffer.
+ */
+ if (CHECK(res.ret <= 0,
+ "bpf_trace_printk: got return value",
+ "ret <= 0 %d test %d\n", res.ret, res.subtest))
+ goto close_prog;
+
+ CHECK(res.subtest != res.num_subtest, "check all subtests ran",
+ "only ran %d of %d tests\n", res.subtest, res.num_subtest);
+
+close_prog:
+ perf_buffer__free(pb);
+ if (!IS_ERR_OR_NULL(link))
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
+}
diff --git a/tools/testing/selftests/bpf/progs/netif_receive_skb.c b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
new file mode 100644
index 0000000..b5148df
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020, Oracle and/or its affiliates. */
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(int));
+} perf_buf_map SEC(".maps");
+
+struct result {
+ int ret;
+ int subtest;
+ int num_subtest;
+};
+
+typedef struct {
+ int counter;
+} atomic_t;
+typedef struct refcount_struct {
+ atomic_t refs;
+} refcount_t;
+
+struct sk_buff {
+ /* field names and sizes should match to those in the kernel */
+ unsigned int len, data_len;
+ __u16 mac_len, hdr_len, queue_mapping;
+ struct net_device *dev;
+ /* order of the fields doesn't matter */
+ refcount_t users;
+ unsigned char *data;
+ char __pkt_type_offset[0];
+ char cb[48];
+};
+
+#define CHECK_PRINTK(_fmt, _p, res) \
+ do { \
+ char fmt[] = _fmt; \
+ ++(res)->num_subtest; \
+ if ((res)->ret >= 0) { \
+ ++(res)->subtest; \
+ (res)->ret = bpf_trace_printk(fmt, sizeof(fmt), \
+ (_p)); \
+ } \
+ } while (0)
+
+/* TRACE_EVENT(netif_receive_skb,
+ * TP_PROTO(struct sk_buff *skb),
+ */
+SEC("tp_btf/netif_receive_skb")
+int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
+{
+ char skb_type[] = "struct sk_buff";
+ struct __btf_ptr nullp = { .ptr = 0, .type = skb_type };
+ struct __btf_ptr p = { .ptr = skb, .type = skb_type };
+ struct result res = { 0, 0 };
+
+ CHECK_PRINTK("%pT\n", &p, &res);
+ CHECK_PRINTK("%pTc\n", &p, &res);
+ CHECK_PRINTK("%pTN\n", &p, &res);
+ CHECK_PRINTK("%pTx\n", &p, &res);
+ CHECK_PRINTK("%pT0\n", &p, &res);
+ CHECK_PRINTK("%pTcNx0\n", &p, &res);
+ CHECK_PRINTK("%pT\n", &nullp, &res);
+ CHECK_PRINTK("%pTc\n", &nullp, &res);
+ CHECK_PRINTK("%pTN\n", &nullp, &res);
+ CHECK_PRINTK("%pTx\n", &nullp, &res);
+ CHECK_PRINTK("%pT0\n", &nullp, &res);
+ CHECK_PRINTK("%pTcNx0\n", &nullp, &res);
+
+ bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
+ &res, sizeof(res));
+
+ return 0;
+}
--
1.8.3.1
On Mon, May 11, 2020 at 10:59 PM Alan Maguire <[email protected]> wrote:
>
> tests verify we get > 0 return value from bpf_trace_print()
> using %pT format specifier with various modifiers/pointer
> values.
>
> Signed-off-by: Alan Maguire <[email protected]>
> ---
There is no need to use perf buffer for returning results to
user-space. See prog_tests/skeleton.c and progs/test_skeleton.c for a
very minimalistic and simple way to do tests like this.
> .../selftests/bpf/prog_tests/trace_printk_btf.c | 83 ++++++++++++++++++++++
> .../selftests/bpf/progs/netif_receive_skb.c | 81 +++++++++++++++++++++
> 2 files changed, 164 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/trace_printk_btf.c
> create mode 100644 tools/testing/selftests/bpf/progs/netif_receive_skb.c
[...]
> diff --git a/tools/testing/selftests/bpf/progs/netif_receive_skb.c b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
> new file mode 100644
> index 0000000..b5148df
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/netif_receive_skb.c
> @@ -0,0 +1,81 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020, Oracle and/or its affiliates. */
> +#include <linux/bpf.h>
> +#include <stdbool.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_endian.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(key_size, sizeof(int));
> + __uint(value_size, sizeof(int));
> +} perf_buf_map SEC(".maps");
> +
> +struct result {
> + int ret;
> + int subtest;
> + int num_subtest;
> +};
> +
> +typedef struct {
> + int counter;
> +} atomic_t;
> +typedef struct refcount_struct {
> + atomic_t refs;
> +} refcount_t;
> +
> +struct sk_buff {
> + /* field names and sizes should match to those in the kernel */
> + unsigned int len, data_len;
> + __u16 mac_len, hdr_len, queue_mapping;
> + struct net_device *dev;
> + /* order of the fields doesn't matter */
> + refcount_t users;
> + unsigned char *data;
> + char __pkt_type_offset[0];
> + char cb[48];
> +};
please use vmlinux.h instead of duplicating these definitions (which
also will start failing, when sk_buff definition will change).
> +
> +#define CHECK_PRINTK(_fmt, _p, res) \
> + do { \
> + char fmt[] = _fmt; \
> + ++(res)->num_subtest; \
> + if ((res)->ret >= 0) { \
> + ++(res)->subtest; \
> + (res)->ret = bpf_trace_printk(fmt, sizeof(fmt), \
> + (_p)); \
> + } \
> + } while (0)
> +
> +/* TRACE_EVENT(netif_receive_skb,
> + * TP_PROTO(struct sk_buff *skb),
> + */
> +SEC("tp_btf/netif_receive_skb")
> +int BPF_PROG(trace_netif_receive_skb, struct sk_buff *skb)
> +{
> + char skb_type[] = "struct sk_buff";
> + struct __btf_ptr nullp = { .ptr = 0, .type = skb_type };
> + struct __btf_ptr p = { .ptr = skb, .type = skb_type };
> + struct result res = { 0, 0 };
> +
> + CHECK_PRINTK("%pT\n", &p, &res);
> + CHECK_PRINTK("%pTc\n", &p, &res);
> + CHECK_PRINTK("%pTN\n", &p, &res);
> + CHECK_PRINTK("%pTx\n", &p, &res);
> + CHECK_PRINTK("%pT0\n", &p, &res);
> + CHECK_PRINTK("%pTcNx0\n", &p, &res);
> + CHECK_PRINTK("%pT\n", &nullp, &res);
> + CHECK_PRINTK("%pTc\n", &nullp, &res);
> + CHECK_PRINTK("%pTN\n", &nullp, &res);
> + CHECK_PRINTK("%pTx\n", &nullp, &res);
> + CHECK_PRINTK("%pT0\n", &nullp, &res);
> + CHECK_PRINTK("%pTcNx0\n", &nullp, &res);
with global variables this would be:
int pT = 0;
int pTc = 0;
/* and so on */
then inside BPF_PROG:
pT = bpf_printk("%pT\n", &p);
pTc = bpf_printk("%pTc\n", &p);
/* and so on */
CHECK_PRINTK isn't necessary, IMO. bpf_printk is defined in bpf_helpers.h
> +
> + bpf_perf_event_output(ctx, &perf_buf_map, BPF_F_CURRENT_CPU,
> + &res, sizeof(res));
> +
> + return 0;
> +}
> --
> 1.8.3.1
>