Hi Masami, >>> Hmm, it sounds simple... maybe we can increment refctr in >>> install_breakpoint/ >>> remove_breakpoint? >> >> Not really, it would be simpler if I can put it inside install_breakpoint(). >> Consider an mmap() case. Probed instruction resides in the text section >> whereas >> reference counter resides in the data section. These sections gets mapped >> using >> separate mmap() calls. So, when process mmaps the text section we will >> change the >> instruction, but section holding the reference counter may not have been >> mapped >> yet in the virtual memory. If so, we will fail to update the reference >> counter. > > Got it. > In such case, maybe we can hook the target page mmapped and do > install_breakpoint() > at that point. Since the instruction is protected by a refctr, unless mmap the > page on where the refctr is, the program doesn't reach the tracepoint. Is > that right? >
You mean, when mmap(text) happens, save the target page somewhere and when mmap(data) happens, update both instruction and ref_ctr? This sounds feasible. Let me think on it. Thanks for suggestion, Ravi
