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    Subject[tip:perf/core] tracing, perf: Implement BPF programs attached to uprobes
    Commit-ID:  04a22fae4cbc1f7d3f7471e9b36359f98bd3f043
    Gitweb: http://git.kernel.org/tip/04a22fae4cbc1f7d3f7471e9b36359f98bd3f043
    Author: Wang Nan <wangnan0@huawei.com>
    AuthorDate: Wed, 1 Jul 2015 02:13:50 +0000
    Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
    CommitDate: Thu, 6 Aug 2015 15:29:14 -0300

    tracing, perf: Implement BPF programs attached to uprobes

    By copying BPF related operation to uprobe processing path, this patch
    allow users attach BPF programs to uprobes like what they are already
    doing on kprobes.

    After this patch, users are allowed to use PERF_EVENT_IOC_SET_BPF on a
    uprobe perf event. Which make it possible to profile user space programs
    and kernel events together using BPF.

    Because of this patch, CONFIG_BPF_EVENTS should be selected by
    CONFIG_UPROBE_EVENT to ensure trace_call_bpf() is compiled even if
    KPROBE_EVENT is not set.

    Signed-off-by: Wang Nan <wangnan0@huawei.com>
    Acked-by: Alexei Starovoitov <ast@plumgrid.com>
    Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
    Cc: Daniel Borkmann <daniel@iogearbox.net>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: He Kuang <hekuang@huawei.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Kaixu Xia <xiakaixu@huawei.com>
    Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Zefan Li <lizefan@huawei.com>
    Cc: pi3orama@163.com
    Link: http://lkml.kernel.org/r/1435716878-189507-3-git-send-email-wangnan0@huawei.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    include/linux/trace_events.h | 5 +++++
    kernel/events/core.c | 4 ++--
    kernel/trace/Kconfig | 2 +-
    kernel/trace/trace_uprobe.c | 5 +++++
    4 files changed, 13 insertions(+), 3 deletions(-)

    diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
    index 180dbf8..ed27917 100644
    --- a/include/linux/trace_events.h
    +++ b/include/linux/trace_events.h
    @@ -243,6 +243,7 @@ enum {
    TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
    TRACE_EVENT_FL_TRACEPOINT_BIT,
    TRACE_EVENT_FL_KPROBE_BIT,
    + TRACE_EVENT_FL_UPROBE_BIT,
    };

    /*
    @@ -257,6 +258,7 @@ enum {
    * USE_CALL_FILTER - For trace internal events, don't use file filter
    * TRACEPOINT - Event is a tracepoint
    * KPROBE - Event is a kprobe
    + * UPROBE - Event is a uprobe
    */
    enum {
    TRACE_EVENT_FL_FILTERED = (1 << TRACE_EVENT_FL_FILTERED_BIT),
    @@ -267,8 +269,11 @@ enum {
    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_KPROBE = (1 << TRACE_EVENT_FL_KPROBE_BIT),
    + TRACE_EVENT_FL_UPROBE = (1 << TRACE_EVENT_FL_UPROBE_BIT),
    };

    +#define TRACE_EVENT_FL_UKPROBE (TRACE_EVENT_FL_KPROBE | TRACE_EVENT_FL_UPROBE)
    +
    struct trace_event_call {
    struct list_head list;
    struct trace_event_class *class;
    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index bdea129..77f9e5d 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -6846,8 +6846,8 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
    if (event->tp_event->prog)
    return -EEXIST;

    - if (!(event->tp_event->flags & TRACE_EVENT_FL_KPROBE))
    - /* bpf programs can only be attached to kprobes */
    + if (!(event->tp_event->flags & TRACE_EVENT_FL_UKPROBE))
    + /* bpf programs can only be attached to u/kprobes */
    return -EINVAL;

    prog = bpf_prog_get(prog_fd);
    diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
    index 3b9a48a..1153c43 100644
    --- a/kernel/trace/Kconfig
    +++ b/kernel/trace/Kconfig
    @@ -434,7 +434,7 @@ config UPROBE_EVENT

    config BPF_EVENTS
    depends on BPF_SYSCALL
    - depends on KPROBE_EVENT
    + depends on KPROBE_EVENT || UPROBE_EVENT
    bool
    default y
    help
    diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
    index aa1ea7b..f97479f 100644
    --- a/kernel/trace/trace_uprobe.c
    +++ b/kernel/trace/trace_uprobe.c
    @@ -1095,11 +1095,15 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
    {
    struct trace_event_call *call = &tu->tp.call;
    struct uprobe_trace_entry_head *entry;
    + struct bpf_prog *prog = call->prog;
    struct hlist_head *head;
    void *data;
    int size, esize;
    int rctx;

    + if (prog && !trace_call_bpf(prog, regs))
    + return;
    +
    esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));

    size = esize + tu->tp.size + dsize;
    @@ -1289,6 +1293,7 @@ static int register_uprobe_event(struct trace_uprobe *tu)
    return -ENODEV;
    }

    + call->flags = TRACE_EVENT_FL_UPROBE;
    call->class->reg = trace_uprobe_register;
    call->data = tu;
    ret = trace_add_event_call(call);

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