// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright 2014, Michael Ellerman, IBM Corp.
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*/
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "ebb.h"
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#define NUMBER_OF_EBBS 50
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/*
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* Test that if we overflow the counter while in the EBB handler, we take
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* another EBB on exiting from the handler.
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*
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* We do this by counting with a stupidly low sample period, causing us to
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* overflow the PMU while we're still in the EBB handler, leading to another
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* EBB.
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*
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* We get out of what would otherwise be an infinite loop by leaving the
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* counter frozen once we've taken enough EBBs.
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*/
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static void ebb_callee(void)
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{
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uint64_t siar, val;
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val = mfspr(SPRN_BESCR);
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if (!(val & BESCR_PMEO)) {
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ebb_state.stats.spurious++;
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goto out;
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}
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ebb_state.stats.ebb_count++;
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trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
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/* Resets the PMC */
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count_pmc(1, sample_period);
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out:
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if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
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/* Reset but leave counters frozen */
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reset_ebb_with_clear_mask(MMCR0_PMAO);
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else
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/* Unfreezes */
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reset_ebb();
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/* Do some stuff to chew some cycles and pop the counter */
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siar = mfspr(SPRN_SIAR);
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trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);
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val = mfspr(SPRN_PMC1);
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trace_log_reg(ebb_state.trace, SPRN_PMC1, val);
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val = mfspr(SPRN_MMCR0);
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trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
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}
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int back_to_back_ebbs(void)
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{
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struct event event;
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SKIP_IF(!ebb_is_supported());
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event_init_named(&event, 0x1001e, "cycles");
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event_leader_ebb_init(&event);
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event.attr.exclude_kernel = 1;
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event.attr.exclude_hv = 1;
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event.attr.exclude_idle = 1;
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FAIL_IF(event_open(&event));
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setup_ebb_handler(ebb_callee);
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FAIL_IF(ebb_event_enable(&event));
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sample_period = 5;
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ebb_freeze_pmcs();
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mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
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ebb_global_enable();
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ebb_unfreeze_pmcs();
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while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
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FAIL_IF(core_busy_loop());
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ebb_global_disable();
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ebb_freeze_pmcs();
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dump_ebb_state();
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event_close(&event);
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FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);
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return 0;
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}
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int main(void)
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{
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return test_harness(back_to_back_ebbs, "back_to_back_ebbs");
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}
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