[lttng-dev] [RFC-Patch 1/2] Add page fault trace event definitions

[Mathieu Desnoyers]

* Francis Deslauriers (fdeslaur at gmail.com) wrote:
> Add page_fault_entry and page_fault_exit event definitions. It will
> allow each architecture to instrument their page faults.
> 
> Signed-off-by: Francis Deslauriers <fdeslaur at gmail.com>
> Reviewed-by: Raphaël Beamonte <raphael.beamonte at polymtl.ca>
> ---
>  include/trace/events/fault.h |   51 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 51 insertions(+)
>  create mode 100644 include/trace/events/fault.h
> 
> diff --git a/include/trace/events/fault.h b/include/trace/events/fault.h
> new file mode 100644
> index 0000000..7256b40
> --- /dev/null
> +++ b/include/trace/events/fault.h
> @@ -0,0 +1,51 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM fault
> +
> +#if !defined(_TRACE_FAULT_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_FAULT_H
> +
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(page_fault_entry,
> +
> +	TP_PROTO(struct pt_regs *regs, unsigned long address,
> +					int write_access),
> +
> +	TP_ARGS(regs, address, write_access),
> +
> +	TP_STRUCT__entry(
> +		__field(	unsigned long,	ip	)
> +		__field(	unsigned long,	addr	)
> +		__field(	int,		write	)

uint8_t,      write

will save some space.

> +	),
> +
> +	TP_fast_assign(
> +		__entry->ip	= regs ? instruction_pointer(regs) : 0UL;
> +		__entry->addr	= address;
> +		__entry->write	= write_access;

Just to be clean, if we use uint8_t:

__entry->write  = !!write_access;

It will map zero/nonzero values to 0 and 1, and thus ensure it can be
represented on a uint8_t.

Thanks,

Mathieu


> +	),
> +
> +	TP_printk("ip=%lu addr=%lu write_access=%d",
> +		__entry->ip, __entry->addr, __entry->write)
> +);
> +
> +TRACE_EVENT(page_fault_exit,
> +
> +	TP_PROTO(int result),
> +
> +	TP_ARGS(result),
> +
> +	TP_STRUCT__entry(
> +		__field(	int,	res	)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->res	= result;
> +	),
> +
> +	TP_printk("result=%d", __entry->res)
> +);
> +
> +#endif /* _TRACE_FAULT_H */
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> -- 
> 1.7.10.4
> 
> 
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-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com