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106 lines
2.0 KiB
106 lines
2.0 KiB
// 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 <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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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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