Re: [PATCH] x86/tracing: introduce enter/exit tracepoint pairs for page faults

[Dave Hansen <dave.hansen@intel.com>]

On 4/14/25 16:22, Junxuan Liao wrote:
> On 4/14/25 6:14 PM, Junxuan Liao wrote:
>> Do people find separate user/kernel tracepoints useful? For me, I can
>> check regs in eBPF tracing code instead.
> I think it might be good to add a field to the tracepoints to indicate
> whether it's in user space or not.

Sounds sane to me.  Doing something like this:

        TP_STRUCT__entry(
                __field(                unsigned long, address  )
                __field(                unsigned long, ip       )
+               __field(                bool	     , user_mode)
                __field(                unsigned long, error_code )
        ),

        TP_fast_assign(
                 __entry->address = address;
                 __entry->ip         = regs->ip;
+                __entry->user_mode  = user_mode(regs);
                 __entry->error_code = error_code;
        ),

seems highly superior to having two sets of tracepoints and static keys.