39fcfb911c
EBB (Event Based Branches) are currently only available on POWER8, so we should skip them on other CPUs. I've found that at least one test loops forever on 970MP (cycles_with_freeze_test). Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org> [mpe: Minor change log editing, add skip to cpu_event_vs_ebb_test] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
109 lines
2.1 KiB
C
109 lines
2.1 KiB
C
/*
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* Copyright 2014, Michael Ellerman, IBM Corp.
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* Licensed under GPLv2.
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*/
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#include <sched.h>
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#include <signal.h>
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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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/*
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* Test that the kernel properly handles PMAE across context switches.
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*
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* We test this by calling into the kernel inside our EBB handler, where PMAE
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* is clear. A cpu eater companion thread is running on the same CPU as us to
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* encourage the scheduler to switch us.
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*
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* The kernel must make sure that when it context switches us back in, it
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* honours the fact that we had PMAE clear.
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*
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* Observed to hit the failing case on the first EBB with a broken kernel.
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*/
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static bool mmcr0_mismatch;
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static uint64_t before, after;
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static void syscall_ebb_callee(void)
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{
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uint64_t 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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count_pmc(1, sample_period);
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before = mfspr(SPRN_MMCR0);
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/* Try and get ourselves scheduled, to force a PMU context switch */
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sched_yield();
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after = mfspr(SPRN_MMCR0);
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if (before != after)
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mmcr0_mismatch = true;
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out:
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reset_ebb();
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}
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static int test_body(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(syscall_ebb_callee);
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ebb_global_enable();
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FAIL_IF(ebb_event_enable(&event));
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mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
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while (ebb_state.stats.ebb_count < 20 && !mmcr0_mismatch)
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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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count_pmc(1, sample_period);
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dump_ebb_state();
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if (mmcr0_mismatch)
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printf("Saw MMCR0 before 0x%lx after 0x%lx\n", before, after);
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event_close(&event);
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FAIL_IF(ebb_state.stats.ebb_count == 0);
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FAIL_IF(mmcr0_mismatch);
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return 0;
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}
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int pmae_handling(void)
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{
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return eat_cpu(test_body);
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}
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int main(void)
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{
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return test_harness(pmae_handling, "pmae_handling");
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}
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