Hi Steve, (Ccing Beau) On Tue, 25 Jan 2022 17:21:14 -0500 Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Tue, 25 Jan 2022 14:07:14 -0800 > Kees Cook <keescook@xxxxxxxxxxxx> wrote: > > > > The tstruct is the TP_STRUCT__entry() and for each __rel_dynamic_array() or > > > __dynamic_array(), the __data_size gets updated and saved into the > > > __data_offsets that holds where each item is. > > > > > > The rel versions sets the offset from its location to the data, where as > > > the non rel versions sets the offset from the beginning of the event to the > > > data. > > > > Could this just be > > > > #define __get_rel_dynamic_array(field) \ > > ((void *)(&__entry->data[__entry->__rel_loc_##field & 0xffff]) > > > > ? > > This is currently user space defined. But since the only user of the rel_* > version hasn't been upstreamed yet, we could change it. But it also > requires changing libtraceevent as it depends on this code too. I think Kees' idea seems better. If you and Beau are good, I will update the macros for __rel_loc. (This requires to change some user-space application which Beau is making too.) > > I'm surprised that it doesn't break with the __get_dynamic_array() > versions, or is that because it's based off of __entry? I think so. Gcc seems to check the size of the data structure where the original base address points. Thank you, > > -- Steve -- Masami Hiramatsu <mhiramat@xxxxxxxxxx>
