lkml.org 
[lkml]   [2024]   [Feb]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 0/7] tracing/probes: Support function parameter access from return probe
On Thu, 29 Feb 2024 15:38:55 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> Hmm, this seems arch_rethook_trampoline caused the issue.
>
> And curiously, it depends on the number of stored data.
>
> OK:
> /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3' >> dynamic_events
> /sys/kernel/tracing # echo 1 > events/fprobes/enable
>
> NG:
> /sys/kernel/tracing # echo 'f vfs_read%return $arg1 $arg2 $arg3 $arg4' >> dynamic_events
> /sys/kernel/tracing # echo 1 > events/fprobes/enable
>
> I also confirmed that on 'vfs_write' caused the same result. 3 arguments(24 bytes) is OK,
> but 4 arguments (32bytes) is NG.

And this may be the fprobe bug. kretprobe events doesn't show this issue.

OK:
/sys/kernel/tracing # echo 'r vfs_read $arg*' >> kprobe_events
/sys/kernel/tracing # echo 1 > events/kprobes/enable

But this is strange because both uses same rethook...

Thank you,

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>

\
 
 \ /
  Last update: 2024-05-27 15:27    [W:6.648 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site