[PATCH v6 bpf-next 0/3] enable BPF_PROG_TEST_RUN for raw_tp

[PATCH v6 bpf-next 0/3] enable BPF_PROG_TEST_RUN for raw_tp

[Song Liu]

This set enables BPF_PROG_TEST_RUN for raw_tracepoint type programs. This
set also enables running the raw_tp program on a specific CPU. This feature
can be used by user space to trigger programs that access percpu resources,
e.g. perf_event, percpu variables.

---

Changes v5 => v6:
1. Optimize the selftest. (John, Andrii)

Changes v4 => v5:
1.Fail test_run with non-zero test.cpu but no BPF_F_TEST_RUN_ON_CPU.
  (Andrii)
2. Add extra check for invalid test.cpu value. (Andrii)
3. Shuffle bpf_test_run_opts to remove holes. (Andrii)
4. Fixes in selftests. (Andrii)

Changes v3 => v4:
1. Use cpu+flags instead of cpu_plus. (Andrii)
2. Rework libbpf support. (Andrii)

Changes v2 => v3:
1. Fix memory leak in the selftest. (Andrii)
2. Use __u64 instead of unsigned long long. (Andrii)

Changes v1 => v2:
1. More checks for retval in the selftest. (John)
2. Remove unnecessary goto in bpf_prog_test_run_raw_tp. (John)

Song Liu (3):
  bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint
  libbpf: support test run of raw tracepoint programs
  selftests/bpf: add raw_tp_test_run

 include/linux/bpf.h                           |  3 +
 include/uapi/linux/bpf.h                      |  7 ++
 kernel/bpf/syscall.c                          |  2 +-
 kernel/trace/bpf_trace.c                      |  1 +
 net/bpf/test_run.c                            | 91 ++++++++++++++++++
 tools/include/uapi/linux/bpf.h                |  7 ++
 tools/lib/bpf/bpf.c                           | 31 ++++++
 tools/lib/bpf/bpf.h                           | 26 +++++
 tools/lib/bpf/libbpf.map                      |  1 +
 tools/lib/bpf/libbpf_internal.h               |  5 +
 .../bpf/prog_tests/raw_tp_test_run.c          | 96 +++++++++++++++++++
 .../bpf/progs/test_raw_tp_test_run.c          | 24 +++++
 12 files changed, 293 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c

--
2.24.1

[PATCH v6 bpf-next 1/3] bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint

[Song Liu]

Add .test_run for raw_tracepoint. Also, introduce a new feature that runs
the target program on a specific CPU. This is achieved by a new flag in
bpf_attr.test, BPF_F_TEST_RUN_ON_CPU. When this flag is set, the program
is triggered on cpu with id bpf_attr.test.cpu. This feature is needed for
BPF programs that handle perf_event and other percpu resources, as the
program can access these resource locally.

Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
 include/linux/bpf.h            |  3 ++
 include/uapi/linux/bpf.h       |  7 +++
 kernel/bpf/syscall.c           |  2 +-
 kernel/trace/bpf_trace.c       |  1 +
 net/bpf/test_run.c             | 91 ++++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  7 +++
 6 files changed, 110 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fc5c901c75421..efa7245ed76e0 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1381,6 +1381,9 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 				     const union bpf_attr *kattr,
 				     union bpf_attr __user *uattr);
+int bpf_prog_test_run_raw_tp(struct bpf_prog *prog,
+			     const union bpf_attr *kattr,
+			     union bpf_attr __user *uattr);
 bool btf_ctx_access(int off, int size, enum bpf_access_type type,
 		    const struct bpf_prog *prog,
 		    struct bpf_insn_access_aux *info);
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index a22812561064a..05e480f66f475 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -424,6 +424,11 @@ enum {
  */
 #define BPF_F_QUERY_EFFECTIVE	(1U << 0)
 
+/* Flags for BPF_PROG_TEST_RUN */
+
+/* If set, run the test on the cpu specified by bpf_attr.test.cpu */
+#define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
+
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
 	/* enabled run_time_ns and run_cnt */
@@ -566,6 +571,8 @@ union bpf_attr {
 						 */
 		__aligned_u64	ctx_in;
 		__aligned_u64	ctx_out;
+		__u32		flags;
+		__u32		cpu;
 	} test;
 
 	struct { /* anonymous struct used by BPF_*_GET_*_ID */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 2740df19f55e9..3bc2ed2e171be 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2979,7 +2979,7 @@ static int bpf_prog_query(const union bpf_attr *attr,
 	}
 }
 
-#define BPF_PROG_TEST_RUN_LAST_FIELD test.ctx_out
+#define BPF_PROG_TEST_RUN_LAST_FIELD test.cpu
 
 static int bpf_prog_test_run(const union bpf_attr *attr,
 			     union bpf_attr __user *uattr)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 36508f46a8dbf..2834866d379ae 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1678,6 +1678,7 @@ const struct bpf_verifier_ops raw_tracepoint_verifier_ops = {
 };
 
 const struct bpf_prog_ops raw_tracepoint_prog_ops = {
+	.test_run = bpf_prog_test_run_raw_tp,
 };
 
 const struct bpf_verifier_ops tracing_verifier_ops = {
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index a66f211726e7c..fde5db93507c4 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -11,6 +11,7 @@
 #include <net/sock.h>
 #include <net/tcp.h>
 #include <linux/error-injection.h>
+#include <linux/smp.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/bpf_test_run.h>
@@ -204,6 +205,9 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 	int b = 2, err = -EFAULT;
 	u32 retval = 0;
 
+	if (kattr->test.flags || kattr->test.cpu)
+		return -EINVAL;
+
 	switch (prog->expected_attach_type) {
 	case BPF_TRACE_FENTRY:
 	case BPF_TRACE_FEXIT:
@@ -236,6 +240,87 @@ int bpf_prog_test_run_tracing(struct bpf_prog *prog,
 	return err;
 }
 
+struct bpf_raw_tp_test_run_info {
+	struct bpf_prog *prog;
+	void *ctx;
+	u32 retval;
+};
+
+static void
+__bpf_prog_test_run_raw_tp(void *data)
+{
+	struct bpf_raw_tp_test_run_info *info = data;
+
+	rcu_read_lock();
+	migrate_disable();
+	info->retval = BPF_PROG_RUN(info->prog, info->ctx);
+	migrate_enable();
+	rcu_read_unlock();
+}
+
+int bpf_prog_test_run_raw_tp(struct bpf_prog *prog,
+			     const union bpf_attr *kattr,
+			     union bpf_attr __user *uattr)
+{
+	void __user *ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
+	__u32 ctx_size_in = kattr->test.ctx_size_in;
+	struct bpf_raw_tp_test_run_info info;
+	int cpu = kattr->test.cpu, err = 0;
+
+	/* doesn't support data_in/out, ctx_out, duration, or repeat */
+	if (kattr->test.data_in || kattr->test.data_out ||
+	    kattr->test.ctx_out || kattr->test.duration ||
+	    kattr->test.repeat)
+		return -EINVAL;
+
+	if (ctx_size_in < prog->aux->max_ctx_offset)
+		return -EINVAL;
+
+	if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 && cpu != 0)
+		return -EINVAL;
+
+	if (ctx_size_in) {
+		info.ctx = kzalloc(ctx_size_in, GFP_USER);
+		if (!info.ctx)
+			return -ENOMEM;
+		if (copy_from_user(info.ctx, ctx_in, ctx_size_in)) {
+			err = -EFAULT;
+			goto out;
+		}
+	} else {
+		info.ctx = NULL;
+	}
+
+	info.prog = prog;
+
+	if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
+	    cpu == smp_processor_id()) {
+		__bpf_prog_test_run_raw_tp(&info);
+	} else {
+		/* smp_call_function_single() also checks cpu_online()
+		 * after csd_lock(). However, since cpu is from user
+		 * space, let's do an extra quick check to filter out
+		 * invalid value before smp_call_function_single().
+		 */
+		if (cpu >= nr_cpu_ids || !cpu_online(cpu)) {
+			err = -ENXIO;
+			goto out;
+		}
+
+		err = smp_call_function_single(cpu, __bpf_prog_test_run_raw_tp,
+					       &info, 1);
+		if (err)
+			goto out;
+	}
+
+	if (copy_to_user(&uattr->test.retval, &info.retval, sizeof(u32)))
+		err = -EFAULT;
+
+out:
+	kfree(info.ctx);
+	return err;
+}
+
 static void *bpf_ctx_init(const union bpf_attr *kattr, u32 max_size)
 {
 	void __user *data_in = u64_to_user_ptr(kattr->test.ctx_in);
@@ -410,6 +495,9 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 	void *data;
 	int ret;
 
+	if (kattr->test.flags || kattr->test.cpu)
+		return -EINVAL;
+
 	data = bpf_test_init(kattr, size, NET_SKB_PAD + NET_IP_ALIGN,
 			     SKB_DATA_ALIGN(sizeof(struct skb_shared_info)));
 	if (IS_ERR(data))
@@ -607,6 +695,9 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
 	if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
 		return -EINVAL;
 
+	if (kattr->test.flags || kattr->test.cpu)
+		return -EINVAL;
+
 	if (size < ETH_HLEN)
 		return -EINVAL;
 
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index a22812561064a..05e480f66f475 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -424,6 +424,11 @@ enum {
  */
 #define BPF_F_QUERY_EFFECTIVE	(1U << 0)
 
+/* Flags for BPF_PROG_TEST_RUN */
+
+/* If set, run the test on the cpu specified by bpf_attr.test.cpu */
+#define BPF_F_TEST_RUN_ON_CPU	(1U << 0)
+
 /* type for BPF_ENABLE_STATS */
 enum bpf_stats_type {
 	/* enabled run_time_ns and run_cnt */
@@ -566,6 +571,8 @@ union bpf_attr {
 						 */
 		__aligned_u64	ctx_in;
 		__aligned_u64	ctx_out;
+		__u32		flags;
+		__u32		cpu;
 	} test;
 
 	struct { /* anonymous struct used by BPF_*_GET_*_ID */
-- 
2.24.1

[PATCH v6 bpf-next 2/3] libbpf: support test run of raw tracepoint programs

[Song Liu]

Add bpf_prog_test_run_opts() with support of new fields in bpf_attr.test,
namely, flags and cpu. Also extend _opts operations to support outputs via
opts.

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
 tools/lib/bpf/bpf.c             | 31 +++++++++++++++++++++++++++++++
 tools/lib/bpf/bpf.h             | 26 ++++++++++++++++++++++++++
 tools/lib/bpf/libbpf.map        |  1 +
 tools/lib/bpf/libbpf_internal.h |  5 +++++
 4 files changed, 63 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 2baa1308737c8..c5a4d8444bf68 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -712,6 +712,37 @@ int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
 	return ret;
 }
 
+int bpf_prog_test_run_opts(int prog_fd, struct bpf_test_run_opts *opts)
+{
+	union bpf_attr attr;
+	int ret;
+
+	if (!OPTS_VALID(opts, bpf_test_run_opts))
+		return -EINVAL;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.test.prog_fd = prog_fd;
+	attr.test.cpu = OPTS_GET(opts, cpu, 0);
+	attr.test.flags = OPTS_GET(opts, flags, 0);
+	attr.test.repeat = OPTS_GET(opts, repeat, 0);
+	attr.test.duration = OPTS_GET(opts, duration, 0);
+	attr.test.ctx_size_in = OPTS_GET(opts, ctx_size_in, 0);
+	attr.test.ctx_size_out = OPTS_GET(opts, ctx_size_out, 0);
+	attr.test.data_size_in = OPTS_GET(opts, data_size_in, 0);
+	attr.test.data_size_out = OPTS_GET(opts, data_size_out, 0);
+	attr.test.ctx_in = ptr_to_u64(OPTS_GET(opts, ctx_in, NULL));
+	attr.test.ctx_out = ptr_to_u64(OPTS_GET(opts, ctx_out, NULL));
+	attr.test.data_in = ptr_to_u64(OPTS_GET(opts, data_in, NULL));
+	attr.test.data_out = ptr_to_u64(OPTS_GET(opts, data_out, NULL));
+
+	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, sizeof(attr));
+	OPTS_SET(opts, data_size_out, attr.test.data_size_out);
+	OPTS_SET(opts, ctx_size_out, attr.test.ctx_size_out);
+	OPTS_SET(opts, duration, attr.test.duration);
+	OPTS_SET(opts, retval, attr.test.retval);
+	return ret;
+}
+
 static int bpf_obj_get_next_id(__u32 start_id, __u32 *next_id, int cmd)
 {
 	union bpf_attr attr;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 8c1ac4b42f908..4f3568e55527c 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -251,6 +251,32 @@ struct bpf_prog_bind_opts {
 
 LIBBPF_API int bpf_prog_bind_map(int prog_fd, int map_fd,
 				 const struct bpf_prog_bind_opts *opts);
+
+struct bpf_test_run_opts {
+	size_t sz; /* size of this struct for forward/backward compatibility */
+	const void *data_in; /* optional */
+	void *data_out;      /* optional */
+	__u32 data_size_in;
+	__u32 data_size_out; /* in: max length of data_out
+			      * out: length of data_out
+			      */
+	const void *ctx_in; /* optional */
+	void *ctx_out;      /* optional */
+	__u32 ctx_size_in;
+	__u32 ctx_size_out; /* in: max length of ctx_out
+			     * out: length of cxt_out
+			     */
+	__u32 retval;        /* out: return code of the BPF program */
+	int repeat;
+	__u32 duration;      /* out: average per repetition in ns */
+	__u32 flags;
+	__u32 cpu;
+};
+#define bpf_test_run_opts__last_field cpu
+
+LIBBPF_API int bpf_prog_test_run_opts(int prog_fd,
+				      struct bpf_test_run_opts *opts);
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 5f054dadf0829..0623e7a99b1ec 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -303,6 +303,7 @@ LIBBPF_0.1.0 {
 LIBBPF_0.2.0 {
 	global:
 		bpf_prog_bind_map;
+		bpf_prog_test_run_opts;
 		bpf_program__section_name;
 		perf_buffer__buffer_cnt;
 		perf_buffer__buffer_fd;
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 4d1c366fca2ca..d2fff18f4cd12 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -136,6 +136,11 @@ static inline bool libbpf_validate_opts(const char *opts,
 	((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
 #define OPTS_GET(opts, field, fallback_value) \
 	(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
+#define OPTS_SET(opts, field, value)		\
+	do {					\
+		if (OPTS_HAS(opts, field))	\
+			(opts)->field = value;	\
+	} while (0)
 
 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
-- 
2.24.1

[PATCH v6 bpf-next 3/3] selftests/bpf: add raw_tp_test_run

[Song Liu]

This test runs test_run for raw_tracepoint program. The test covers ctx
input, retval output, and running on correct cpu.

Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
---
 .../bpf/prog_tests/raw_tp_test_run.c          | 96 +++++++++++++++++++
 .../bpf/progs/test_raw_tp_test_run.c          | 24 +++++
 2 files changed, 120 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
 create mode 100644 tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c

diff --git a/tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c b/tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
new file mode 100644
index 0000000000000..c5fb191874acf
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/raw_tp_test_run.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2019 Facebook */
+#include <test_progs.h>
+#include <linux/bpf.h>
+#include "bpf/libbpf_internal.h"
+#include "test_raw_tp_test_run.skel.h"
+
+static int duration;
+
+void test_raw_tp_test_run(void)
+{
+	struct bpf_prog_test_run_attr test_attr = {};
+	int comm_fd = -1, err, nr_online, i, prog_fd;
+	__u64 args[2] = {0x1234ULL, 0x5678ULL};
+	int expected_retval = 0x1234 + 0x5678;
+	struct test_raw_tp_test_run *skel;
+	char buf[] = "new_name";
+	bool *online = NULL;
+	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
+			    .ctx_in = args,
+			    .ctx_size_in = sizeof(args),
+			    .flags = BPF_F_TEST_RUN_ON_CPU,
+		);
+
+	err = parse_cpu_mask_file("/sys/devices/system/cpu/online", &online,
+				  &nr_online);
+	if (CHECK(err, "parse_cpu_mask_file", "err %d\n", err))
+		return;
+
+	skel = test_raw_tp_test_run__open_and_load();
+	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))
+		goto cleanup;
+
+	err = test_raw_tp_test_run__attach(skel);
+	if (CHECK(err, "skel_attach", "skeleton attach failed: %d\n", err))
+		goto cleanup;
+
+	comm_fd = open("/proc/self/comm", O_WRONLY|O_TRUNC);
+	if (CHECK(comm_fd < 0, "open /proc/self/comm", "err %d\n", errno))
+		goto cleanup;
+
+	err = write(comm_fd, buf, sizeof(buf));
+	CHECK(err < 0, "task rename", "err %d", errno);
+
+	CHECK(skel->bss->count == 0, "check_count", "didn't increase\n");
+	CHECK(skel->data->on_cpu != 0xffffffff, "check_on_cpu", "got wrong value\n");
+
+	prog_fd = bpf_program__fd(skel->progs.rename);
+	test_attr.prog_fd = prog_fd;
+	test_attr.ctx_in = args;
+	test_attr.ctx_size_in = sizeof(__u64);
+
+	err = bpf_prog_test_run_xattr(&test_attr);
+	CHECK(err == 0, "test_run", "should fail for too small ctx\n");
+
+	test_attr.ctx_size_in = sizeof(args);
+	err = bpf_prog_test_run_xattr(&test_attr);
+	CHECK(err < 0, "test_run", "err %d\n", errno);
+	CHECK(test_attr.retval != expected_retval, "check_retval",
+	      "expect 0x%x, got 0x%x\n", expected_retval, test_attr.retval);
+
+	for (i = 0; i < nr_online; i++) {
+		if (!online[i])
+			continue;
+
+		opts.cpu = i;
+		opts.retval = 0;
+		err = bpf_prog_test_run_opts(prog_fd, &opts);
+		CHECK(err < 0, "test_run_opts", "err %d\n", errno);
+		CHECK(skel->data->on_cpu != i, "check_on_cpu",
+		      "expect %d got %d\n", i, skel->data->on_cpu);
+		CHECK(opts.retval != expected_retval,
+		      "check_retval", "expect 0x%x, got 0x%x\n",
+		      expected_retval, opts.retval);
+	}
+
+	/* invalid cpu ID should fail with ENXIO */
+	opts.cpu = 0xffffffff;
+	err = bpf_prog_test_run_opts(prog_fd, &opts);
+	CHECK(err != -1 || errno != ENXIO,
+	      "test_run_opts_fail",
+	      "should failed with ENXIO\n");
+
+	/* non-zero cpu w/o BPF_F_TEST_RUN_ON_CPU should fail with EINVAL */
+	opts.cpu = 1;
+	opts.flags = 0;
+	err = bpf_prog_test_run_opts(prog_fd, &opts);
+	CHECK(err != -1 || errno != EINVAL,
+	      "test_run_opts_fail",
+	      "should failed with EINVAL\n");
+
+cleanup:
+	close(comm_fd);
+	test_raw_tp_test_run__destroy(skel);
+	free(online);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c b/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
new file mode 100644
index 0000000000000..1521853597d70
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_raw_tp_test_run.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+__u32 count = 0;
+__u32 on_cpu = 0xffffffff;
+
+SEC("raw_tp/task_rename")
+int BPF_PROG(rename, struct task_struct *task, char *comm)
+{
+
+	count++;
+	if ((__u64) task == 0x1234ULL && (__u64) comm == 0x5678ULL) {
+		on_cpu = bpf_get_smp_processor_id();
+		return (int)task + (int)comm;
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
-- 
2.24.1

Re: [PATCH v6 bpf-next 0/3] enable BPF_PROG_TEST_RUN for raw_tp

[Daniel Borkmann]

On 9/25/20 10:54 PM, Song Liu wrote:
> This set enables BPF_PROG_TEST_RUN for raw_tracepoint type programs. This
> set also enables running the raw_tp program on a specific CPU. This feature
> can be used by user space to trigger programs that access percpu resources,
> e.g. perf_event, percpu variables.

Applied, thanks!

Re: [PATCH v6 bpf-next 1/3] bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint

[Alexei Starovoitov]

On Fri, Sep 25, 2020 at 1:55 PM Song Liu <songliubraving@fb.com> wrote:
> +
> +       if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
> +           cpu == smp_processor_id()) {
> +               __bpf_prog_test_run_raw_tp(&info);

That's broken:
[   35.874974] BUG: using smp_processor_id() in preemptible [00000000]
code: new_name/87
[   35.893983] caller is bpf_prog_test_run_raw_tp+0xd4/0x1b0
[   35.900124] CPU: 1 PID: 87 Comm: new_name Not tainted 5.9.0-rc6-g615bd02bf #1
[   35.907358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.10.2-1ubuntu1 04/01/2014
[   35.916941] Call Trace:
[   35.919660]  dump_stack+0x77/0x9b
[   35.923273]  check_preemption_disabled+0xb4/0xc0
[   35.928376]  bpf_prog_test_run_raw_tp+0xd4/0x1b0
[   35.933872]  ? selinux_bpf+0xd/0x70
[   35.937532]  __do_sys_bpf+0x6bb/0x21e0
[   35.941570]  ? find_held_lock+0x2d/0x90
[   35.945687]  ? vfs_write+0x150/0x220
[   35.949586]  do_syscall_64+0x2d/0x40
[   35.953443]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Please fix and add debug flags to your .config.

Re: [PATCH v6 bpf-next 1/3] bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint

[Song Liu]

> On Sep 29, 2020, at 11:24 AM, Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:
> 
> On Fri, Sep 25, 2020 at 1:55 PM Song Liu <songliubraving@fb.com> wrote:
>> +
>> +       if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
>> +           cpu == smp_processor_id()) {
>> +               __bpf_prog_test_run_raw_tp(&info);
> 
> That's broken:
> [   35.874974] BUG: using smp_processor_id() in preemptible [00000000]
> code: new_name/87
> [   35.893983] caller is bpf_prog_test_run_raw_tp+0xd4/0x1b0
> [   35.900124] CPU: 1 PID: 87 Comm: new_name Not tainted 5.9.0-rc6-g615bd02bf #1
> [   35.907358] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
> BIOS 1.10.2-1ubuntu1 04/01/2014
> [   35.916941] Call Trace:
> [   35.919660]  dump_stack+0x77/0x9b
> [   35.923273]  check_preemption_disabled+0xb4/0xc0
> [   35.928376]  bpf_prog_test_run_raw_tp+0xd4/0x1b0
> [   35.933872]  ? selinux_bpf+0xd/0x70
> [   35.937532]  __do_sys_bpf+0x6bb/0x21e0
> [   35.941570]  ? find_held_lock+0x2d/0x90
> [   35.945687]  ? vfs_write+0x150/0x220
> [   35.949586]  do_syscall_64+0x2d/0x40
> [   35.953443]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Please fix and add debug flags to your .config.

Hmm... I do have most debug flags enabled. But I didn't have CONFIG_PREEMPT. 
I will keep that on..

Thanks,
Song