Messages in this thread | | | Date | Thu, 28 Jan 2021 09:09:35 +0900 | From | Masami Hiramatsu <> | Subject | Re: [PATCH] tracing/kprobe: Fix to support kretprobe events on unloaded modules |
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On Wed, 27 Jan 2021 17:29:50 -0500 Steven Rostedt <rostedt@goodmis.org> wrote:
> On Thu, 28 Jan 2021 00:37:51 +0900 > Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > Fix kprobe_on_func_entry() returns error code instead of false so that > > register_kretprobe() can return an appropriate error code. > > > > append_trace_kprobe() expects the kprobe registration returns -ENOENT > > when the target symbol is not found, and it checks whether the target > > module is unloaded or not. If the target module doesn't exist, it > > defers to probe the target symbol until the module is loaded. > > > > However, since register_kretprobe() returns -EINVAL instead of -ENOENT > > in that case, it always fail on putting the kretprobe event on unloaded > > modules. e.g. > > > > Kprobe event: > > /sys/kernel/debug/tracing # echo p xfs:xfs_end_io >> kprobe_events > > [ 16.515574] trace_kprobe: This probe might be able to register after target module is loaded. Continue. > > > > Kretprobe event: (p -> r) > > /sys/kernel/debug/tracing # echo r xfs:xfs_end_io >> kprobe_events > > sh: write error: Invalid argument > > /sys/kernel/debug/tracing # cat error_log > > [ 41.122514] trace_kprobe: error: Failed to register probe event > > Command: r xfs:xfs_end_io > > ^ > > > > To fix this bug, change kprobe_on_func_entry() to detect symbol lookup > > failure and return -ENOENT in that case. Otherwise it returns -EINVAL > > or 0 (succeeded, given address is on the entry). > > > > Reported-by: Jianlin Lv <Jianlin.Lv@arm.com> > > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> > > Is this something that should go to stable? And if so, can you supply a > Fixes tag?
Yes, I thought that had not supported previously, but that's wrong. I found below commit introduced -ENOENT check in trace_kprobe side.
Fixes: 59158ec4aef7 ("tracing/kprobes: Check the probe on unloaded module correctly")
Thank you,
-- Masami Hiramatsu <mhiramat@kernel.org>
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