On Thu, 28 Apr 2022 20:09:45 -0400 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > OK, I think I see the issue you have. Because the functions shown in > available_filter_functions which uses the simple "%ps" to show the function > name: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/ftrace.c#n3692 > > And the code that does the actual matching uses kallsyms_lookup() > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/trace/ftrace.c#n4017 > > Which appears not to match the function for the address, you can't pass in > __bpf_tramp_exit because it wont match the symbol returned by > kallsyms_lookup. Never mind, in testing this I had marked the weak function as notrace, which was the reason I couldn't add it to the set_ftrace_notrace. After removing the notrace, kallsyms_lookup() doesn't make a difference. It appears that kallsyms will include overridden weak functions into the size of the function before it. I tried: ret = kallsyms_lookup(rec->ip, &size, &offset, &modname, str); if (!ret || offset > size) { seq_printf(m, "no function at %lx", rec->ip); } else { seq_printf(m, "%s", str); if (modname) seq_printf(m, " [%s]", modname); } And it made no difference. > > This does indeed look like a bug in %ps. > Yes, this does appear to be a issue with kallsyms in general. -- Steve
