diff mbox series

[v4,bpf-next,1/3] bpf: enable BPF_PROG_TEST_RUN for raw_tracepoint

Message ID 20200924011951.408313-2-songliubraving@fb.com
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series enable BPF_PROG_TEST_RUN for raw_tp | expand

Commit Message

Song Liu Sept. 24, 2020, 1:19 a.m. UTC 
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>
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             | 89 ++++++++++++++++++++++++++++++++++
 tools/include/uapi/linux/bpf.h |  7 +++
 6 files changed, 108 insertions(+), 1 deletion(-)

Comments

Andrii Nakryiko Sept. 24, 2020, 7:56 p.m. UTC | #1 
On Wed, Sep 23, 2020 at 6:46 PM Song Liu <songliubraving@fb.com> wrote:
>
> 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>
> 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             | 89 ++++++++++++++++++++++++++++++++++
>  tools/include/uapi/linux/bpf.h |  7 +++
>  6 files changed, 108 insertions(+), 1 deletion(-)
>

[...]

> +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, 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)

duration and repeat sound generally useful (benchmarking raw_tp
programs), so it's a pity you haven't implemented them. But it can be
added later, so not a deal breaker.

> +               return -EINVAL;
> +
> +       if (ctx_size_in < prog->aux->max_ctx_offset)
> +               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;
> +       cpu = kattr->test.cpu;
> +
> +       if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
> +           cpu == smp_processor_id()) {

should we enforce that cpu == 0 if BPF_F_TEST_RUN_ON_CPU is not set?


> +               __bpf_prog_test_run_raw_tp(&info);
> +       } else {
> +               /* smp_call_function_single() also checks cpu_online()
> +                * after csd_lock(). However, since cpu_plus is from user

cpu_plus leftover in a comment

> +                * space, let's do an extra quick check to filter out
> +                * invalid value before smp_call_function_single().
> +                */
> +               if (!cpu_online(cpu)) {

briefly looking at cpu_online() code, it seems like it's not checking
that cpu is < NR_CPUS. Should we add a selftest that validates that
passing unreasonable cpu index doesn't generate warning or invalid
memory access?

> +                       err = -ENXIO;
> +                       goto out;
> +               }
> +
> +               err = smp_call_function_single(cpu, __bpf_prog_test_run_raw_tp,
> +                                              &info, 1);
> +               if (err)
> +                       goto out;
> +       }
> +

[...]
Song Liu Sept. 24, 2020, 8:49 p.m. UTC | #2 
> On Sep 24, 2020, at 12:56 PM, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
> 
> On Wed, Sep 23, 2020 at 6:46 PM Song Liu <songliubraving@fb.com> wrote:
>> 
>> 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>
>> 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             | 89 ++++++++++++++++++++++++++++++++++
>> tools/include/uapi/linux/bpf.h |  7 +++
>> 6 files changed, 108 insertions(+), 1 deletion(-)
>> 
> 
> [...]
> 
>> +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, 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)
> 
> duration and repeat sound generally useful (benchmarking raw_tp
> programs), so it's a pity you haven't implemented them. But it can be
> added later, so not a deal breaker.
> 
>> +               return -EINVAL;
>> +
>> +       if (ctx_size_in < prog->aux->max_ctx_offset)
>> +               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;
>> +       cpu = kattr->test.cpu;
>> +
>> +       if ((kattr->test.flags & BPF_F_TEST_RUN_ON_CPU) == 0 ||
>> +           cpu == smp_processor_id()) {
> 
> should we enforce that cpu == 0 if BPF_F_TEST_RUN_ON_CPU is not set?

Added a test. 

> 
> 
>> +               __bpf_prog_test_run_raw_tp(&info);
>> +       } else {
>> +               /* smp_call_function_single() also checks cpu_online()
>> +                * after csd_lock(). However, since cpu_plus is from user
> 
> cpu_plus leftover in a comment

Fixed. 

> 
>> +                * space, let's do an extra quick check to filter out
>> +                * invalid value before smp_call_function_single().
>> +                */
>> +               if (!cpu_online(cpu)) {
> 
> briefly looking at cpu_online() code, it seems like it's not checking
> that cpu is < NR_CPUS. Should we add a selftest that validates that
> passing unreasonable cpu index doesn't generate warning or invalid
> memory access?

Good catch! We need extra "cpu >= nr_cpu_ids".

Thanks,
Song
diff mbox series

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index d7c5a6ed87e30..23758c282eb4b 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1376,6 +1376,9 @@  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 ec68d3a23a2b7..684bc29515664 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -2975,7 +2975,7 @@  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 b2a5380eb1871..4553aebf53862 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1675,6 +1675,7 @@  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 99eb8c6c0fbcc..1411bc665be6b 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 +240,85 @@  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, 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 (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;
+	cpu = kattr->test.cpu;
+
+	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_plus is from user
+		 * space, let's do an extra quick check to filter out
+		 * invalid value before smp_call_function_single().
+		 */
+		if (!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 +493,9 @@  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 +693,9 @@  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 */