** Also affects: linux (Ubuntu Zesty)
Importance: Medium
Assignee: dann frazier (dannf)
Status: In Progress
** Also affects: linux (Ubuntu Yakkety)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Zesty)
Status: In Progress => Fix Released
** Changed in: linux (Ubuntu Yakkety)
Status: New => In Progress
** Changed in: linux (Ubuntu Yakkety)
Assignee: (unassigned) => dann frazier (dannf)
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https://bugs.launchpad.net/bugs/1634271
Title:
arm64: kprobes disabled
Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Yakkety:
In Progress
Status in linux source package in Zesty:
Fix Released
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()).
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