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authorAlexei Starovoitov <ast@plumgrid.com>2015-03-25 20:49:23 +0100
committerIngo Molnar <mingo@kernel.org>2015-04-02 13:25:50 +0200
commitb896c4f95ab4052d6bad3acde95167d30242a84f (patch)
tree8c18a3ca9f2b389823d7181db606fa3c8d2eccc7 /samples/bpf/libbpf.h
parenttracing: Allow BPF programs to call bpf_trace_printk() (diff)
downloadlinux-b896c4f95ab4052d6bad3acde95167d30242a84f.tar.xz
linux-b896c4f95ab4052d6bad3acde95167d30242a84f.zip
samples/bpf: Add simple non-portable kprobe filter example
tracex1_kern.c - C program compiled into BPF. It attaches to kprobe:netif_receive_skb() When skb->dev->name == "lo", it prints sample debug message into trace_pipe via bpf_trace_printk() helper function. tracex1_user.c - corresponding user space component that: - loads BPF program via bpf() syscall - opens kprobes:netif_receive_skb event via perf_event_open() syscall - attaches the program to event via ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd); - prints from trace_pipe Note, this BPF program is non-portable. It must be recompiled with current kernel headers. kprobe is not a stable ABI and BPF+kprobe scripts may no longer be meaningful when kernel internals change. No matter in what way the kernel changes, neither the kprobe, nor the BPF program can ever crash or corrupt the kernel, assuming the kprobes, perf and BPF subsystem has no bugs. The verifier will detect that the program is using bpf_trace_printk() and the kernel will print 'this is a DEBUG kernel' warning banner, which means that bpf_trace_printk() should be used for debugging of the BPF program only. Usage: $ sudo tracex1 ping-19826 [000] d.s2 63103.382648: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63103.382684: : skb ffff880466b1d300 len 84 ping-19826 [000] d.s2 63104.382533: : skb ffff880466b1ca00 len 84 ping-19826 [000] d.s2 63104.382594: : skb ffff880466b1d300 len 84 Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Cc: Arnaldo Carvalho de Melo <acme@infradead.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David S. Miller <davem@davemloft.net> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/1427312966-8434-7-git-send-email-ast@plumgrid.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'samples/bpf/libbpf.h')
-rw-r--r--samples/bpf/libbpf.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/samples/bpf/libbpf.h b/samples/bpf/libbpf.h
index 58c5fe1bdba1..ac7b09672b46 100644
--- a/samples/bpf/libbpf.h
+++ b/samples/bpf/libbpf.h
@@ -13,7 +13,7 @@ int bpf_get_next_key(int fd, void *key, void *next_key);
int bpf_prog_load(enum bpf_prog_type prog_type,
const struct bpf_insn *insns, int insn_len,
- const char *license);
+ const char *license, int kern_version);
#define LOG_BUF_SIZE 65536
extern char bpf_log_buf[LOG_BUF_SIZE];
@@ -182,4 +182,7 @@ extern char bpf_log_buf[LOG_BUF_SIZE];
/* create RAW socket and bind to interface 'name' */
int open_raw_sock(const char *name);
+struct perf_event_attr;
+int perf_event_open(struct perf_event_attr *attr, int pid, int cpu,
+ int group_fd, unsigned long flags);
#endif