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user_events: Add basic perf and eBPF support 

Adds support to write out user_event data to perf_probe/perf files as
well as to any attached eBPF program.

Link: https://lkml.kernel.org/r/20220118204326.2169-5-beaub@linux.microsoft.com

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Beau Belgrave 2022-01-18 12:43:18 -08:00 committed by Steven Rostedt (Google)
parent 9aed4e157d
commit 3207d0459e
1 changed files with 71 additions and 1 deletions
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72
kernel/trace/trace_events_user.c
View File

@ -551,6 +551,50 @@ 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.
*/
@ -573,6 +617,10 @@ 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);
@ -612,8 +660,27 @@ 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;
@ -870,6 +937,9 @@ 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);