Re: [PATCH] uprobes: list all active uprobes in the system

[Longjun Luo]

在 1/13/2023 12:03 PM, Ravi Bangoria 写道:
> +cc: Steven, Oleg, Masami
>
> On 11-Jan-23 4:18 PM, luolongjun@xxxxxxxxxx wrote:
> > From: Longjun Luo <luolongjun@xxxxxxxxxx>
> >
> > Since uprobes will replace instructions in the process
> > memory, it is necessary to provide one way to list
> > all active uprobes. One can access this file through
> > /sys/kernel/debug/uprobes/list.
> >
> > Output looks like this
> > =====================
> > inode+offset/ref_ctr_offset    4160760670+0x30a10/0x0
> >      ref                        1
> >      register_rwsem             (unlocked)
> >      consumer_rwsem             (unlocked)
> >      consumers-1
> >          handler                0xffffffffc03ee02e(handler) uprobe
> >          ret_handler            0x0000000000000000( )
> >          filter                 0xffffffffc03ee010(filter) uprobe
> >      consumers-2
> >          handler                0xffffffffc03e902e(handler_1) uprobe_1
> >          ret_handler            0x0000000000000000( )
> >          filter                 0xffffffffc03e9010(filter_1) uprobe_1
> You can list uprobes via /sys/kernel/tracing/uprobe_events. Any specific reason
> to introduce another way?
>
> Thanks,
> Ravi

/sys/kernel/tracing/uprobe_events only lists tracing events, not all uprobe events.
For example, if I write a kernel module to call the uprobe_register to add a new uprobe event, it will not be listed by /sys/kernel/tracing/uprobe_events.

Compare it with the kprobe is like:
/sys/kernel/tracing/uprobe_events -> /sys/kernel/tracing/kprobe_events
/sys/kernel/debug/uprobes/list -> /sys/kernel/debug/kprobes/list

Nowadays, only the trace system uses the uprobe, so /sys/kernel/tracing/uprobe_events is enough.

But we try to extend the usage of the uprobe, and we add many uprobe events by calling the uprobe_register.

For this situation, we need a approach to see all the uprobe events in the kernel.