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Subject: Re: kernelshark plugins and ftrace array fields
From: Steven Rostedt <rostedt@goodmis.org>
To: Avi Kivity <avi@redhat.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
        KVM list <kvm@vger.kernel.org>
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Date: Thu, 02 Sep 2010 15:24:03 -0400
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On Thu, 2010-09-02 at 14:38 -0400, Steven Rostedt wrote:

> I think I will add a:
> 
> void *pevent_get_field_raw(stuct trace_seq *s,
> 			struct event_format *event, 
> 			char *field_name,
> 			struct record *record,
> 			int **field_len);
> 
> which will return a pointer into record->data and set the field_len to
> the actual size.
> 
> This will be useful for dynamic arrays too, since it is more complex
> than just using a field->offset.

I just pushed out the changes and my new example looks like this:

static int
kvm_emulate_insn_handler(struct trace_seq *s, struct record *record,
                         struct event_format *event, void *context)
{
        unsigned char *data;
        int len;
        int i;

        data = pevent_get_field_raw(s, event, "insn", record,
                                    &len, 1);
        if (!data)
                return -1;

        trace_seq_puts(s, "insn: ");
        for (i = 0; i < len; i++) {
                trace_seq_printf(s, "%s%02x",
                                 i ? "," : "",
                                 data[i]);
        }

        return 0;
}