RE: [patch 9/9] x86, bts, ftrace: a BTS ftrace plug-in prototype

From: Metzger, Markus T
Date: Tue Nov 25 2008 - 06:23:31 EST


>-----Original Message-----
>From: Frédéric Weisbecker [mailto:fweisbec@xxxxxxxxx]
>Sent: Dienstag, 25. November 2008 11:40
>To: Metzger, Markus T

>2008/11/25 Markus Metzger <markus.t.metzger@xxxxxxxxx>:
>> +static enum print_line_t bts_trace_print_line(struct
>trace_iterator *iter)
>> +{
>> + struct trace_entry *entry = iter->ent;
>> + struct trace_seq *seq = &iter->seq;
>> + struct bts_entry *it;
>> +
>> + trace_assign_type(it, entry);
>> +
>> + if (entry->type == TRACE_BTS) {
>> + int ret;
>> +#ifdef CONFIG_KALLSYMS
>> + char function[KSYM_SYMBOL_LEN];
>> + sprint_symbol(function, it->from);
>> +#else
>> + char *function = "<unknown>";
>> +#endif
>> +
>> + ret = trace_seq_printf(seq, "%4d 0x%lx ->
>0x%lx [%s]\n",
>> + entry->cpu, it->from,
>it->to, function);
>
>
>You can use seq_print_ip_sym() which handles the ifdef and the
>sprint_symbol...

Thanks.


>> +void trace_bts(struct trace_array *tr, unsigned long from,
>unsigned long to)
>> +{
>> + struct ring_buffer_event *event;
>> + struct bts_entry *entry;
>> + unsigned long irq;
>> +
>> + event = ring_buffer_lock_reserve(tr->buffer,
>sizeof(*entry), &irq);
>> + if (!event)
>> + return;
>> + entry = ring_buffer_event_data(event);
>> + tracing_generic_entry_update(&entry->ent, 0, from);
>> + entry->ent.type = TRACE_BTS;
>> + entry->ent.cpu = smp_processor_id();
>
>
>If you look at the struct trace_entry, you will see find the cpu
>field. It is already inserted automatically :-)

I am using that field in struct trace_entry.

Without the assignment, though, I've seen funny cpu numbers. It seems that the field is not filled automatically.


regards,
markus.
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