Messages in this thread | | | From | Jeff Xie <> | Date | Fri, 3 Jun 2022 00:23:14 +0800 | Subject | Re: [PATCH v10 2/4] trace/objtrace: Get the value of the object |
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Hi Masami,
On Wed, Jun 1, 2022 at 11:13 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > On Tue, 31 May 2022 15:13:24 +0800 > Jeff Xie <xiehuan09@gmail.com> wrote: > > > Hi Masami and steve, > > > > On Sun, May 22, 2022 at 10:22 PM Masami Hiramatsu <mhiramat@kernel.org> wrote: > > > > > > Hi Jeff, > > > > > > On Fri, 13 May 2022 01:00:06 +0800 > > > Jeff Xie <xiehuan09@gmail.com> wrote: > > > > > > [...] > > > > @@ -175,9 +271,27 @@ trace_object_trigger(struct event_trigger_data *data, > > > > > > > > field = obj_data->field; > > > > memcpy(&obj, rec + field->offset, sizeof(obj)); > > > > - set_trace_object(obj, tr); > > > > + /* set the offset from the special object and the type size of the value*/ > > > > + set_trace_object(obj, obj_data->obj_offset, > > > > + obj_data->obj_value_type_size, tr); > > > > } > > > > > > > > +static const struct objtrace_fetch_type objtrace_fetch_types[] = { > > > > + {"u8", 1}, > > > > + {"s8", 1}, > > > > + {"x8", 1}, > > > > + {"u16", 2}, > > > > + {"s16", 2}, > > > > + {"x16", 2}, > > > > + {"u32", 4}, > > > > + {"s32", 4}, > > > > + {"x32", 4}, > > > > + {"u64", 8}, > > > > + {"s64", 8}, > > > > + {"x64", 8}, > > > > > > Hmm, as far as I can see, you don't distinguish the prefix 'u','s','x'. > > > If so, please support only 'x' at this moment. kprobe events supports > > > those types, and it distinguishes the types when printing the logged > > > data. E.g. 's16' shows '-1' for 0xffff, but 'x16' shows '0xffff'. > > > You can add another patch to support such different types afterwards. > > > > I feel to let the objtrace trigger to distinguish the prefix 'u', 's', > > 'x', It seems a very challenging work ;-) > > I spent a lot of time thinking, I would like to add a callback > > function(print function) in the struct trace_object_entry for each > > data type. > > Not sure if this is possible or allowed, as I haven't seen any example > > like this to add function in the struct *_entry ;-) > > Hmm, I don't recommend this, becuase this event record can be exposed > to user space as binary data. So please do not put such a function > pointer which will be used in the ftrace directly. > Instead, add a new event type of the object-trace for each type-prefix, > since each of them has different print-fmt.
This place is still a difficult point for me ;-)
> Anyway I would like to ask you is to share the next version of the > series without that improvement. You can improve it after merging the > basic feature. No need to stop the series until all possible feature > set are implemented (unless it will change the user-exposed interface > much.)
Thanks for your suggestion, I will submit the next version.
> > > > > The following is part of the code I have prepared. I don't know if you > > can give any suggestions or wait until I submit the next version to > > discuss. > > But thanks for sharing the code. This helps me to understand what you > are trying :) > > Thank you, > > > > > > > <snip> > > diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h > > index 2407c45a568c..5f8289e26f91 100644 > > --- a/kernel/trace/trace_entries.h > > +++ b/kernel/trace/trace_entries.h > > @@ -414,6 +414,7 @@ FTRACE_ENTRY(object, trace_object_entry, > > __field( unsigned long, parent_ip ) > > __field( unsigned long, object ) > > __field( unsigned long, value ) > > + __field( unsigned long, print ) > > ), > > > > +/* get the type size for the special object */ > > +struct objtrace_fetch_type { > > + char *name; > > + int type_size; > > + int is_signed; > > + print_type_func_t print; > > +}; > > + > > > > static const struct objtrace_fetch_type objtrace_fetch_types[] = { > > - {"x8", 1}, > > - {"x16", 2}, > > - {"x32", 4}, > > - {"x64", 8}, > > - {NULL, 0} > > + {"u8", 1, 0, PRINT_TYPE_FUNC_NAME(u8)}, > > + {"s8", 1, 1, PRINT_TYPE_FUNC_NAME(s8)}, > > + {"x8", 1, 0, PRINT_TYPE_FUNC_NAME(x8)}, > > + {"u16", 2, 0, PRINT_TYPE_FUNC_NAME(u16)}, > > + {"s16", 2, 1, PRINT_TYPE_FUNC_NAME(s16)}, > > + {"x16", 2, 0, PRINT_TYPE_FUNC_NAME(x16)}, > > + {"u32", 4, 0, PRINT_TYPE_FUNC_NAME(u32)}, > > + {"s32", 4, 1, PRINT_TYPE_FUNC_NAME(s32)}, > > + {"x32", 4, 0, PRINT_TYPE_FUNC_NAME(x32)}, > > + {"u64", 8, 0, PRINT_TYPE_FUNC_NAME(u64)}, > > + {"s64", 8, 1, PRINT_TYPE_FUNC_NAME(s64)}, > > + {"x64", 8, 1, PRINT_TYPE_FUNC_NAME(x64)}, > > + {NULL, 0, 0, NULL} > > }; > > </snip> > > > > > > + {} > > > > > > If this array is null terminated, please explictly do that, like > > > > > > {NULL, 0}, > > > > > > for readability. > > > > > > Thank you, > > > > > > -- > > > Masami Hiramatsu (Google) <mhiramat@kernel.org> > > > > Thanks, > > JeffXie > > > -- > Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks, JeffXie
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