** Description changed: [Impact] - kprobes are not available on arm64, a useful debug feature available on all other supported Ubuntu architectures. I failed to catch this when I reviewed the yakkety config because I was just looking for regressions vs. enabling new features (arm64/kprobes is new in 4.8). + kprobes is currently enabled for all Ubuntu architectures except arm64. This excludes a useful debug feature, which is required by certain userspace provided by Ubuntu, such as perf's probe command. I failed to notice this in my yakkety config review because it is a new feature in v4.8. [Test Case] - sudo perf probe schedule - sudo perf record -e probe:schedule -aR sleep 1 + = Failure case = + ubuntu@arm64:~$ sudo perf probe schedule + kprobe_events file does not exist - please rebuild kernel with CONFIG_KPROBE_EVENTS. + Error: Failed to add events. + + = Success case = + ubuntu@arm64:~$ sudo perf probe schedule + Added new event: + probe:schedule (on schedule) + + You can now use it in all perf tools, such as: + + perf record -e probe:schedule -aR sleep 1 + + ubuntu@arm64:~$ sudo perf record -e probe:schedule -aR sleep 1 + [ perf record: Woken up 1 times to write data ] + [ perf record: Captured and wrote 0.185 MB perf.data (61 samples) ] [Regression Risk] The proposed fix enables a config for an already-upstream feature, so regressions will have upstream support. The config change mostly results in building new code vs. modifying existing code. The notable exception is that arm64's notify_page_fault() will now get code to call kprobe_fault_handler() - but only in the case that this newly enabled feature is being used (if kprobe_running()).
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1634271 Title: arm64: kprobes disabled Status in linux package in Ubuntu: In Progress Bug description: [Impact] kprobes is currently enabled for all Ubuntu architectures except arm64. This excludes a useful debug feature, which is required by certain userspace provided by Ubuntu, such as perf's probe command. I failed to notice this in my yakkety config review because it is a new feature in v4.8. [Test Case] = Failure case = ubuntu@arm64:~$ sudo perf probe schedule kprobe_events file does not exist - please rebuild kernel with CONFIG_KPROBE_EVENTS. Error: Failed to add events. = Success case = ubuntu@arm64:~$ sudo perf probe schedule Added new event: probe:schedule (on schedule) You can now use it in all perf tools, such as: perf record -e probe:schedule -aR sleep 1 ubuntu@arm64:~$ sudo perf record -e probe:schedule -aR sleep 1 [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.185 MB perf.data (61 samples) ] [Regression Risk] The proposed fix enables a config for an already-upstream feature, so regressions will have upstream support. The config change mostly results in building new code vs. modifying existing code. The notable exception is that arm64's notify_page_fault() will now get code to call kprobe_fault_handler() - but only in the case that this newly enabled feature is being used (if kprobe_running()). To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1634271/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
