ARC: perf: Add kernel callchain support

#include <linux/perf_event.h>

#include <linux/platform_device.h>

#include <asm/arcregs.h>

#include <asm/stacktrace.h>

struct arc_pmu {

	struct pmu	pmu;

	int		ev_hw_idx[PERF_COUNT_ARC_HW_MAX];

};

struct arc_callchain_trace {

	int depth;

	void *perf_stuff;

};

static int callchain_trace(unsigned int addr, void *data)

{

	struct arc_callchain_trace *ctrl = data;

	struct perf_callchain_entry *entry = ctrl->perf_stuff;

	perf_callchain_store(entry, addr);

	if (ctrl->depth++ < 3)

		return 0;

	return -1;

}

void

perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)

{

	struct arc_callchain_trace ctrl = {

		.depth = 0,

		.perf_stuff = entry,

	};

	arc_unwind_core(NULL, regs, callchain_trace, &ctrl);

}

static struct arc_pmu *arc_pmu;

/* read counter #idx; note that counter# != event# on ARC! */