text: /*
   * Copyright 2014, Michael Ellerman, IBM Corp.
   * Licensed under GPLv2.
   */
  
  #include <stdbool.h>
  #include <stdio.h>
  #include <stdlib.h>
  
  #include "ebb.h"
  
  
  #define NUMBER_OF_EBBS	50
  
  /*
   * Test that if we overflow the counter while in the EBB handler, we take
   * another EBB on exiting from the handler.
   *
   * We do this by counting with a stupidly low sample period, causing us to
   * overflow the PMU while we're still in the EBB handler, leading to another
   * EBB.
   *
   * We get out of what would otherwise be an infinite loop by leaving the
   * counter frozen once we've taken enough EBBs.
   */
  
  static void ebb_callee(void)
  {
  	uint64_t siar, val;
  
  	val = mfspr(SPRN_BESCR);
  	if (!(val & BESCR_PMEO)) {
  		ebb_state.stats.spurious++;
  		goto out;
  	}
  
  	ebb_state.stats.ebb_count++;
  	trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
  
  	/* Resets the PMC */
  	count_pmc(1, sample_period);
  
  out:
  	if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
  		/* Reset but leave counters frozen */
  		reset_ebb_with_clear_mask(MMCR0_PMAO);
  	else
  		/* Unfreezes */
  		reset_ebb();
  
  	/* Do some stuff to chew some cycles and pop the counter */
  	siar = mfspr(SPRN_SIAR);
  	trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);
  
  	val = mfspr(SPRN_PMC1);
  	trace_log_reg(ebb_state.trace, SPRN_PMC1, val);
  
  	val = mfspr(SPRN_MMCR0);
  	trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
  }
  
  int back_to_back_ebbs(void)
  {
  	struct event event;
  
  	event_init_named(&event, 0x1001e, "cycles");
  	event_leader_ebb_init(&event);
  
  	event.attr.exclude_kernel = 1;
  	event.attr.exclude_hv = 1;
  	event.attr.exclude_idle = 1;
  
  	FAIL_IF(event_open(&event));
  
  	setup_ebb_handler(ebb_callee);
  
  	FAIL_IF(ebb_event_enable(&event));
  
  	sample_period = 5;
  
  	ebb_freeze_pmcs();
  	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
  	ebb_global_enable();
  	ebb_unfreeze_pmcs();
  
  	while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
  		FAIL_IF(core_busy_loop());
  
  	ebb_global_disable();
  	ebb_freeze_pmcs();
  
  	count_pmc(1, sample_period);
  
  	dump_ebb_state();
  
  	event_close(&event);
  
  	FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);
  
  	return 0;
  }
  
  int main(void)
  {
  	return test_harness(back_to_back_ebbs, "back_to_back_ebbs");
  }
  