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    Subject[PATCH v8 04/12] user_events: Add basic perf and eBPF support
    Date
    Adds support to write out user_event data to perf_probe/perf files as
    well as to any attached eBPF program.

    Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
    ---
    kernel/trace/trace_events_user.c | 72 +++++++++++++++++++++++++++++++-
    1 file changed, 71 insertions(+), 1 deletion(-)

    diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c
    index 9859e62b9838..cc30d1fcbb63 100644
    --- a/kernel/trace/trace_events_user.c
    +++ b/kernel/trace/trace_events_user.c
    @@ -550,6 +550,50 @@ static void user_event_ftrace(struct user_event *user, void *data, u32 datalen,
    trace_event_buffer_commit(&event_buffer);
    }

    +#ifdef CONFIG_PERF_EVENTS
    +/*
    + * Writes the user supplied payload out to perf ring buffer or eBPF program.
    + */
    +static void user_event_perf(struct user_event *user, void *data, u32 datalen,
    + void *tpdata)
    +{
    + struct hlist_head *perf_head;
    +
    + if (bpf_prog_array_valid(&user->call)) {
    + struct user_bpf_context context = {0};
    +
    + context.data_len = datalen;
    + context.data_type = USER_BPF_DATA_KERNEL;
    + context.kdata = data;
    +
    + trace_call_bpf(&user->call, &context);
    + }
    +
    + perf_head = this_cpu_ptr(user->call.perf_events);
    +
    + if (perf_head && !hlist_empty(perf_head)) {
    + struct trace_entry *perf_entry;
    + struct pt_regs *regs;
    + size_t size = sizeof(*perf_entry) + datalen;
    + int context;
    +
    + perf_entry = perf_trace_buf_alloc(ALIGN(size, 8),
    + &regs, &context);
    +
    + if (unlikely(!perf_entry))
    + return;
    +
    + perf_fetch_caller_regs(regs);
    +
    + memcpy(perf_entry + 1, data, datalen);
    +
    + perf_trace_buf_submit(perf_entry, size, context,
    + user->call.event.type, 1, regs,
    + perf_head, NULL);
    + }
    +}
    +#endif
    +
    /*
    * Update the register page that is shared between user processes.
    */
    @@ -572,6 +616,10 @@ static void update_reg_page_for(struct user_event *user)

    if (probe_func == user_event_ftrace)
    status |= EVENT_STATUS_FTRACE;
    +#ifdef CONFIG_PERF_EVENTS
    + else if (probe_func == user_event_perf)
    + status |= EVENT_STATUS_PERF;
    +#endif
    else
    status |= EVENT_STATUS_OTHER;
    } while ((++probe_func_ptr)->func);
    @@ -611,8 +659,27 @@ static int user_event_reg(struct trace_event_call *call,
    data);
    goto dec;

    - default:
    +#ifdef CONFIG_PERF_EVENTS
    + case TRACE_REG_PERF_REGISTER:
    + ret = tracepoint_probe_register(call->tp,
    + call->class->perf_probe,
    + data);
    + if (!ret)
    + goto inc;
    + break;
    +
    + case TRACE_REG_PERF_UNREGISTER:
    + tracepoint_probe_unregister(call->tp,
    + call->class->perf_probe,
    + data);
    + goto dec;
    +
    + case TRACE_REG_PERF_OPEN:
    + case TRACE_REG_PERF_CLOSE:
    + case TRACE_REG_PERF_ADD:
    + case TRACE_REG_PERF_DEL:
    break;
    +#endif
    }

    return ret;
    @@ -864,6 +931,9 @@ static int user_event_parse(char *name, char *args, char *flags,
    user->class.get_fields = user_event_get_fields;
    user->class.reg = user_event_reg;
    user->class.probe = user_event_ftrace;
    +#ifdef CONFIG_PERF_EVENTS
    + user->class.perf_probe = user_event_perf;
    +#endif

    mutex_lock(&event_mutex);
    ret = user_event_trace_register(user);
    --
    2.17.1
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