more issues in kernel function support

[honggyukim]

@namhyung I've tested some features for kernel function tracing and have some comments as follows:

1. time filter for kernel functions in record command doesn't filter-out kernel functions that spent less time than threshold. (maybe already aware of it)
2. 'trace' trigger is not working for kernel functions
3. graph command result seems to include kernel functions out of main function by default and --kernel-skip-out option is not working with graph command. This is tested when kernel function is given as last argument. (e.g. __do_page_fault)

Please have a look at it.

[namhyung]

1. Yep, it should be supported by kernel. In fact kernel has an option for this but it only shows "exit" records so I decided not use it for now.
2. it needs to be implemented in kernel. Did you mean at replay?
3. it looks like a bug. I'll take a look it.

[honggyukim]

2 . Yes, I mean 'trace' trigger support for replay command.

[namhyung]

For item 2, it was because filter address requires full 64 bit address but file format only saves 48 bit to reduce space. We need to sign-extend the address before giving it to filters. Does below patch fixes the issue?

diff --git a/utils/kernel.c b/utils/kernel.c
index d886cc0..4c8052c 100644
--- a/utils/kernel.c
+++ b/utils/kernel.c
@@ -872,13 +872,16 @@ static int read_kernel_cpu(struct ftrace_file_handle *handle, int cpu)
                        if (delta < handle->time_filter) {
                                struct ftrace_session *sess = first_session;
                                struct ftrace_trigger tr = {};
+                               unsigned long real_addr;

+                               /* filter match needs full (64-bit) address */
+                               real_addr = get_real_address(curr->addr);
                                /*
                                 * it might set TRACE trigger, which shows
                                 * function even if it's less than the time filter.
                                 */
                                ftrace_match_filter(&sess->filters,
-                                                   curr->addr, &tr);
+                                                   real_addr, &tr);
                                if (tr.flags & TRIGGER_FL_TRACE) {
                                        add_to_rstack_list(rstack_list, curr, NULL);
                                        break;

[honggyukim]

It works fine with above patch. Thanks!

[namhyung]

For item 3, I think below patch should fix it.

diff --git a/cmd-graph.c b/cmd-graph.c
index 49460a5..fc207fd 100644
--- a/cmd-graph.c
+++ b/cmd-graph.c
@@ -394,6 +394,12 @@ static int build_graph(struct opts *opts, struct ftrace_file_handle *handle, cha
                struct sym *sym = NULL;
                char *name;

+               if (opts->kernel_skip_out) {
+                       /* skip kernel functions outside user functions */
+                       if (!task->user_stack_count && is_kernel_address(frs->addr))
+                               continue;
+               }
+
                if (!fstack_check_filter(task))
                        continue;

[namhyung]

@honggyukim can you please check the current code and close this issue if it's done?

[honggyukim]

@namhyung Yeap, I tested it and found that all the issues are resolved now. Sorry for the late answer.