[PATCH RFC v7 net-next 17/28] tracing: allow eBPF programs to be attached to events

From: Alexei Starovoitov
Date: Tue Aug 26 2014 - 22:30:56 EST

User interface:
fd = open("/sys/kernel/debug/tracing/__event__/filter")

write(fd, "bpf_123")

where 123 is process local FD associated with eBPF program previously loaded.
__event__ is static tracepoint event or syscall.
(kprobe support is in next patch)
Once program is successfully attached to tracepoint event, the tracepoint
will be auto-enabled

close(fd)
auto-disables tracepoint event and detaches eBPF program from it

eBPF programs can call in-kernel helper functions to:
- lookup/update/delete elements in maps
- memcmp
- dump_stack
- fetch_ptr/u64/u32/u16/u8 values from unsafe address via probe_kernel_read(),
so that eBPF program can walk any kernel data structures

Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
---
fs/btrfs/super.c | 3 +
include/linux/ftrace_event.h | 5 +
include/trace/bpf_trace.h | 23 +++++
include/trace/ftrace.h | 25 +++++
include/uapi/linux/bpf.h | 8 ++
kernel/trace/Kconfig | 1 +
kernel/trace/Makefile | 1 +
kernel/trace/bpf_trace.c | 183 ++++++++++++++++++++++++++++++++++++
kernel/trace/trace.h | 3 +
kernel/trace/trace_events.c | 41 +++++++-
kernel/trace/trace_events_filter.c | 72 +++++++++++++-
kernel/trace/trace_syscalls.c | 32 +++++++
12 files changed, 395 insertions(+), 2 deletions(-)
create mode 100644 include/trace/bpf_trace.h
create mode 100644 kernel/trace/bpf_trace.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index c4124de4435b..274d20752e07 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -61,6 +61,9 @@
#include "tests/btrfs-tests.h"

#define CREATE_TRACE_POINTS
+/* dummy definition to make compiler happy */
+struct __btrfs_workqueue {
+};
#include <trace/events/btrfs.h>

static const struct super_operations btrfs_super_ops;
diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index 28672e87e910..10602bfa07fe 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -237,6 +237,7 @@ enum {
TRACE_EVENT_FL_WAS_ENABLED_BIT,
TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
TRACE_EVENT_FL_TRACEPOINT_BIT,
+ TRACE_EVENT_FL_BPF_BIT,
};

/*
@@ -259,6 +260,7 @@ enum {
TRACE_EVENT_FL_WAS_ENABLED = (1 << TRACE_EVENT_FL_WAS_ENABLED_BIT),
TRACE_EVENT_FL_USE_CALL_FILTER = (1 << TRACE_EVENT_FL_USE_CALL_FILTER_BIT),
TRACE_EVENT_FL_TRACEPOINT = (1 << TRACE_EVENT_FL_TRACEPOINT_BIT),
+ TRACE_EVENT_FL_BPF = (1 << TRACE_EVENT_FL_BPF_BIT),
};

struct ftrace_event_call {
@@ -533,6 +535,9 @@ event_trigger_unlock_commit_regs(struct ftrace_event_file *file,
event_triggers_post_call(file, tt);
}

+struct bpf_context;
+void trace_filter_call_bpf(struct event_filter *filter, struct bpf_context *ctx);
+
enum {
FILTER_OTHER = 0,
FILTER_STATIC_STRING,
diff --git a/include/trace/bpf_trace.h b/include/trace/bpf_trace.h
new file mode 100644
index 000000000000..6074cc917800
--- /dev/null
+++ b/include/trace/bpf_trace.h
@@ -0,0 +1,23 @@
+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * 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.
+ */
+#ifndef _LINUX_KERNEL_BPF_TRACE_H
+#define _LINUX_KERNEL_BPF_TRACE_H
+
+/* For tracing filters save first six arguments of tracepoint events.
+ * argN fields match one to one to arguments passed to tracepoint events.
+ */
+struct bpf_context {
+ u64 arg1;
+ u64 arg2;
+ u64 arg3;
+ u64 arg4;
+ u64 arg5;
+ u64 arg6;
+ u64 ret;
+};
+
+#endif /* _LINUX_KERNEL_BPF_TRACE_H */
diff --git a/include/trace/ftrace.h b/include/trace/ftrace.h
index 26b4f2e13275..4c7d59bdc24a 100644
--- a/include/trace/ftrace.h
+++ b/include/trace/ftrace.h
@@ -17,6 +17,7 @@
*/

#include <linux/ftrace_event.h>
+#include <trace/bpf_trace.h>

/*
* DECLARE_EVENT_CLASS can be used to add a generic function
@@ -619,6 +620,20 @@ static inline notrace int ftrace_get_offsets_##call( \
#undef __perf_task
#define __perf_task(t) (t)

+/* cast any interger or pointer type to u64 without warnings */
+#define __CAST_TO_U64(expr) \
+ __builtin_choose_expr(sizeof(long) < sizeof(expr), \
+ (u64) (expr - ((typeof(expr))0)), \
+ (u64) (long) expr)
+
+#define __BPF_CAST1(a,...) __CAST_TO_U64(a)
+#define __BPF_CAST2(a,...) __CAST_TO_U64(a), __BPF_CAST1(__VA_ARGS__)
+#define __BPF_CAST3(a,...) __CAST_TO_U64(a), __BPF_CAST2(__VA_ARGS__)
+#define __BPF_CAST4(a,...) __CAST_TO_U64(a), __BPF_CAST3(__VA_ARGS__)
+#define __BPF_CAST5(a,...) __CAST_TO_U64(a), __BPF_CAST4(__VA_ARGS__)
+#define __BPF_CAST6(a,...) __CAST_TO_U64(a), __BPF_CAST5(__VA_ARGS__)
+#define __BPF_CAST(a,...) __CAST_TO_U64(a), __BPF_CAST6(__VA_ARGS__)
+
#undef DECLARE_EVENT_CLASS
#define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print) \
\
@@ -634,6 +649,16 @@ ftrace_raw_event_##call(void *__data, proto) \
if (ftrace_trigger_soft_disabled(ftrace_file)) \
return; \
\
+ if (unlikely(ftrace_file->flags & FTRACE_EVENT_FL_FILTERED) && \
+ unlikely(ftrace_file->event_call->flags & TRACE_EVENT_FL_BPF)) { \
+ struct bpf_context __ctx = ((struct bpf_context) { \
+ __BPF_CAST(args, 0, 0, 0, 0, 0, 0) \
+ }); \
+ \
+ trace_filter_call_bpf(ftrace_file->filter, &__ctx); \
+ return; \
+ } \
+ \
__data_size = ftrace_get_offsets_##call(&__data_offsets, args); \
\
entry = ftrace_event_buffer_reserve(&fbuffer, ftrace_file, \
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index f87b501b2e1b..55adff33083e 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -378,6 +378,7 @@ enum bpf_map_type {
enum bpf_prog_type {
BPF_PROG_TYPE_UNSPEC,
BPF_PROG_TYPE_SOCKET_FILTER,
+ BPF_PROG_TYPE_TRACING_FILTER,
};

union bpf_attr {
@@ -422,6 +423,13 @@ enum bpf_func_id {
BPF_FUNC_map_lookup_elem, /* void *map_lookup_elem(&map, &key) */
BPF_FUNC_map_update_elem, /* int map_update_elem(&map, &key, &value) */
BPF_FUNC_map_delete_elem, /* int map_delete_elem(&map, &key) */
+ BPF_FUNC_fetch_ptr, /* void *bpf_fetch_ptr(void *unsafe_ptr) */
+ BPF_FUNC_fetch_u64, /* u64 bpf_fetch_u64(void *unsafe_ptr) */
+ BPF_FUNC_fetch_u32, /* u32 bpf_fetch_u32(void *unsafe_ptr) */
+ BPF_FUNC_fetch_u16, /* u16 bpf_fetch_u16(void *unsafe_ptr) */
+ BPF_FUNC_fetch_u8, /* u8 bpf_fetch_u8(void *unsafe_ptr) */
+ BPF_FUNC_memcmp, /* int bpf_memcmp(void *unsafe_ptr, void *safe_ptr, int size) */
+ BPF_FUNC_dump_stack, /* void bpf_dump_stack(void) */
__BPF_FUNC_MAX_ID,
};

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a5da09c899dd..038424e54443 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -75,6 +75,7 @@ config FTRACE_NMI_ENTER

config EVENT_TRACING
select CONTEXT_SWITCH_TRACER
+ select BPF
bool

config CONTEXT_SWITCH_TRACER
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 67d6369ddf83..fe897168a19e 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -53,6 +53,7 @@ obj-$(CONFIG_EVENT_TRACING) += trace_event_perf.o
endif
obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
obj-$(CONFIG_EVENT_TRACING) += trace_events_trigger.o
+obj-$(CONFIG_EVENT_TRACING) += bpf_trace.o
obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
obj-$(CONFIG_TRACEPOINTS) += power-traces.o
ifeq ($(CONFIG_PM_RUNTIME),y)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
new file mode 100644
index 000000000000..b4751e2c0d52
--- /dev/null
+++ b/kernel/trace/bpf_trace.c
@@ -0,0 +1,183 @@
+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/uaccess.h>
+#include <trace/bpf_trace.h>
+#include "trace.h"
+
+static u64 bpf_fetch_ptr(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ void *unsafe_ptr = (void *) (long) r1;
+ void *ptr = NULL;
+
+ probe_kernel_read(&ptr, unsafe_ptr, sizeof(ptr));
+ return (u64) (unsigned long) ptr;
+}
+
+#define FETCH(SIZE) \
+static u64 bpf_fetch_##SIZE(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) \
+{ \
+ void *unsafe_ptr = (void *) (long) r1; \
+ SIZE val = 0; \
+ \
+ probe_kernel_read(&val, unsafe_ptr, sizeof(val)); \
+ return (u64) (SIZE) val; \
+}
+FETCH(u64)
+FETCH(u32)
+FETCH(u16)
+FETCH(u8)
+#undef FETCH
+
+static u64 bpf_memcmp(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ void *unsafe_ptr = (void *) (long) r1;
+ void *safe_ptr = (void *) (long) r2;
+ u32 size = (u32) r3;
+ char buf[64];
+ int err;
+
+ if (size < 64) {
+ err = probe_kernel_read(buf, unsafe_ptr, size);
+ if (err)
+ return err;
+ return memcmp(buf, safe_ptr, size);
+ }
+ return -1;
+}
+
+static u64 bpf_dump_stack(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ trace_dump_stack(0);
+ return 0;
+}
+
+static struct bpf_func_proto tracing_filter_funcs[] = {
+#define FETCH(SIZE) \
+ [BPF_FUNC_fetch_##SIZE] = { \
+ .func = bpf_fetch_##SIZE, \
+ .gpl_only = false, \
+ .ret_type = RET_INTEGER, \
+ },
+ FETCH(ptr)
+ FETCH(u64)
+ FETCH(u32)
+ FETCH(u16)
+ FETCH(u8)
+#undef FETCH
+ [BPF_FUNC_memcmp] = {
+ .func = bpf_memcmp,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_ANYTHING,
+ .arg2_type = ARG_PTR_TO_STACK,
+ .arg3_type = ARG_CONST_STACK_SIZE,
+ },
+ [BPF_FUNC_dump_stack] = {
+ .func = bpf_dump_stack,
+ .gpl_only = false,
+ .ret_type = RET_VOID,
+ },
+ [BPF_FUNC_map_lookup_elem] = {
+ .func = bpf_map_lookup_elem,
+ .gpl_only = false,
+ .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_MAP_KEY,
+ },
+ [BPF_FUNC_map_update_elem] = {
+ .func = bpf_map_update_elem,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_MAP_KEY,
+ .arg3_type = ARG_PTR_TO_MAP_VALUE,
+ },
+ [BPF_FUNC_map_delete_elem] = {
+ .func = bpf_map_delete_elem,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_MAP_KEY,
+ },
+};
+
+static const struct bpf_func_proto *tracing_filter_func_proto(enum bpf_func_id func_id)
+{
+ if (func_id < 0 || func_id >= ARRAY_SIZE(tracing_filter_funcs))
+ return NULL;
+ return &tracing_filter_funcs[func_id];
+}
+
+static const struct bpf_context_access {
+ int size;
+ enum bpf_access_type type;
+} tracing_filter_ctx_access[] = {
+ [offsetof(struct bpf_context, arg1)] = {
+ FIELD_SIZEOF(struct bpf_context, arg1),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg2)] = {
+ FIELD_SIZEOF(struct bpf_context, arg2),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg3)] = {
+ FIELD_SIZEOF(struct bpf_context, arg3),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg4)] = {
+ FIELD_SIZEOF(struct bpf_context, arg4),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg5)] = {
+ FIELD_SIZEOF(struct bpf_context, arg5),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg6)] = {
+ FIELD_SIZEOF(struct bpf_context, arg6),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, ret)] = {
+ FIELD_SIZEOF(struct bpf_context, ret),
+ BPF_READ
+ },
+};
+
+static bool tracing_filter_is_valid_access(int off, int size, enum bpf_access_type type)
+{
+ const struct bpf_context_access *access;
+
+ if (off < 0 || off >= ARRAY_SIZE(tracing_filter_ctx_access))
+ return false;
+
+ access = &tracing_filter_ctx_access[off];
+ if (access->size == size && (access->type & type))
+ return true;
+
+ return false;
+}
+
+static struct bpf_verifier_ops tracing_filter_ops = {
+ .get_func_proto = tracing_filter_func_proto,
+ .is_valid_access = tracing_filter_is_valid_access,
+};
+
+static struct bpf_prog_type_list tl = {
+ .ops = &tracing_filter_ops,
+ .type = BPF_PROG_TYPE_TRACING_FILTER,
+};
+
+static int __init register_tracing_filter_ops(void)
+{
+ bpf_register_prog_type(&tl);
+ return 0;
+}
+late_initcall(register_tracing_filter_ops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 385391fb1d3b..f0b7caa71b9d 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -986,12 +986,15 @@ struct ftrace_event_field {
int is_signed;
};

+struct bpf_prog;
+
struct event_filter {
int n_preds; /* Number assigned */
int a_preds; /* allocated */
struct filter_pred *preds;
struct filter_pred *root;
char *filter_string;
+ struct bpf_prog *prog;
};

struct event_subsystem {
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index ef06ce7e9cf8..181820f3a571 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1051,6 +1051,26 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
return r;
}

+static int event_filter_release(struct inode *inode, struct file *filp)
+{
+ struct ftrace_event_file *file;
+ char buf[2] = "0";
+
+ mutex_lock(&event_mutex);
+ file = event_file_data(filp);
+ if (file) {
+ if (file->event_call->flags & TRACE_EVENT_FL_BPF) {
+ /* auto-disable the filter */
+ ftrace_event_enable_disable(file, 0);
+
+ /* if BPF filter was used, clear it on fd close */
+ apply_event_filter(file, buf);
+ }
+ }
+ mutex_unlock(&event_mutex);
+ return 0;
+}
+
static ssize_t
event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,
loff_t *ppos)
@@ -1074,10 +1094,28 @@ event_filter_write(struct file *filp, const char __user *ubuf, size_t cnt,

mutex_lock(&event_mutex);
file = event_file_data(filp);
- if (file)
+ if (file) {
+ /*
+ * note to user space tools:
+ * write() into debugfs/tracing/events/xxx/filter file
+ * must be done with the same privilege level as open()
+ */
err = apply_event_filter(file, buf);
+ if (!err && file->event_call->flags & TRACE_EVENT_FL_BPF)
+ /* once filter is applied, auto-enable it */
+ ftrace_event_enable_disable(file, 1);
+ }
+
mutex_unlock(&event_mutex);

+ if (file && file->event_call->flags & TRACE_EVENT_FL_BPF) {
+ /*
+ * allocate per-cpu printk buffers, since eBPF program
+ * might be calling bpf_trace_printk
+ */
+ trace_printk_init_buffers();
+ }
+
free_page((unsigned long) buf);
if (err < 0)
return err;
@@ -1328,6 +1366,7 @@ static const struct file_operations ftrace_event_filter_fops = {
.open = tracing_open_generic,
.read = event_filter_read,
.write = event_filter_write,
+ .release = event_filter_release,
.llseek = default_llseek,
};

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 7a8c1528e141..401fca436054 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -23,6 +23,9 @@
#include <linux/mutex.h>
#include <linux/perf_event.h>
#include <linux/slab.h>
+#include <linux/bpf.h>
+#include <trace/bpf_trace.h>
+#include <linux/filter.h>

#include "trace.h"
#include "trace_output.h"
@@ -535,6 +538,16 @@ static int filter_match_preds_cb(enum move_type move, struct filter_pred *pred,
return WALK_PRED_DEFAULT;
}

+void trace_filter_call_bpf(struct event_filter *filter, struct bpf_context *ctx)
+{
+ BUG_ON(!filter || !filter->prog);
+
+ rcu_read_lock();
+ BPF_PROG_RUN(filter->prog, (void *) ctx);
+ rcu_read_unlock();
+}
+EXPORT_SYMBOL_GPL(trace_filter_call_bpf);
+
/* return 1 if event matches, 0 otherwise (discard) */
int filter_match_preds(struct event_filter *filter, void *rec)
{
@@ -789,6 +802,8 @@ static void __free_filter(struct event_filter *filter)
if (!filter)
return;

+ if (filter->prog)
+ bpf_prog_put(filter->prog);
__free_preds(filter);
kfree(filter->filter_string);
kfree(filter);
@@ -1857,6 +1872,48 @@ static int create_filter_start(char *filter_str, bool set_str,
return err;
}

+static int create_filter_bpf(char *filter_str, struct event_filter **filterp)
+{
+ struct event_filter *filter;
+ struct bpf_prog *prog;
+ long ufd;
+ int err = 0;
+
+ *filterp = NULL;
+
+ filter = __alloc_filter();
+ if (!filter)
+ return -ENOMEM;
+
+ err = replace_filter_string(filter, filter_str);
+ if (err)
+ goto free_filter;
+
+ err = kstrtol(filter_str + 4, 0, &ufd);
+ if (err)
+ goto free_filter;
+
+ err = -ESRCH;
+ prog = bpf_prog_get(ufd);
+ if (!prog)
+ goto free_filter;
+
+ filter->prog = prog;
+
+ err = -EINVAL;
+ if (prog->info->prog_type != BPF_PROG_TYPE_TRACING_FILTER)
+ /* prog_id is valid, but it's not a tracing filter program */
+ goto free_filter;
+
+ *filterp = filter;
+
+ return 0;
+
+free_filter:
+ __free_filter(filter);
+ return err;
+}
+
static void create_filter_finish(struct filter_parse_state *ps)
{
if (ps) {
@@ -1966,7 +2023,20 @@ int apply_event_filter(struct ftrace_event_file *file, char *filter_string)
return 0;
}

- err = create_filter(call, filter_string, true, &filter);
+ /*
+ * 'bpf_123' string is a request to attach eBPF program with id == 123
+ * also accept 'bpf 123', 'bpf.123', 'bpf-123' variants
+ */
+ if (memcmp(filter_string, "bpf", 3) == 0 && filter_string[3] != 0 &&
+ filter_string[4] != 0) {
+ err = create_filter_bpf(filter_string, &filter);
+ if (!err)
+ call->flags |= TRACE_EVENT_FL_BPF;
+ } else {
+ err = create_filter(call, filter_string, true, &filter);
+ if (!err)
+ call->flags &= ~TRACE_EVENT_FL_BPF;
+ }

/*
* Always swap the call filter with the new filter
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index 759d5e004517..7a3d0623763f 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -7,6 +7,7 @@
#include <linux/ftrace.h>
#include <linux/perf_event.h>
#include <asm/syscall.h>
+#include <trace/bpf_trace.h>

#include "trace_output.h"
#include "trace.h"
@@ -299,6 +300,21 @@ static int __init syscall_exit_define_fields(struct ftrace_event_call *call)
return ret;
}

+static void populate_bpf_ctx(struct bpf_context *ctx, struct pt_regs *regs)
+{
+ struct task_struct *task = current;
+ unsigned long args[6];
+
+ syscall_get_arguments(task, regs, 0, 6, args);
+ ctx->arg1 = args[0];
+ ctx->arg2 = args[1];
+ ctx->arg3 = args[2];
+ ctx->arg4 = args[3];
+ ctx->arg5 = args[4];
+ ctx->arg6 = args[5];
+ ctx->ret = syscall_get_return_value(task, regs);
+}
+
static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
{
struct trace_array *tr = data;
@@ -328,6 +344,14 @@ static void ftrace_syscall_enter(void *data, struct pt_regs *regs, long id)
if (!sys_data)
return;

+ if (ftrace_file->event_call->flags & TRACE_EVENT_FL_BPF) {
+ struct bpf_context ctx;
+
+ populate_bpf_ctx(&ctx, regs);
+ trace_filter_call_bpf(ftrace_file->filter, &ctx);
+ return;
+ }
+
size = sizeof(*entry) + sizeof(unsigned long) * sys_data->nb_args;

local_save_flags(irq_flags);
@@ -375,6 +399,14 @@ static void ftrace_syscall_exit(void *data, struct pt_regs *regs, long ret)
if (!sys_data)
return;

+ if (ftrace_file->event_call->flags & TRACE_EVENT_FL_BPF) {
+ struct bpf_context ctx;
+
+ populate_bpf_ctx(&ctx, regs);
+ trace_filter_call_bpf(ftrace_file->filter, &ctx);
+ return;
+ }
+
local_save_flags(irq_flags);
pc = preempt_count();

--
1.7.9.5

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