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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright 2014, Michael Ellerman, IBM Corp.4 */5 6#include <sched.h>7#include <signal.h>8#include <stdbool.h>9#include <stdio.h>10#include <stdlib.h>11 12#include "ebb.h"13 14 15/*16 * Test that the kernel properly handles PMAE across context switches.17 *18 * We test this by calling into the kernel inside our EBB handler, where PMAE19 * is clear. A cpu eater companion thread is running on the same CPU as us to20 * encourage the scheduler to switch us.21 *22 * The kernel must make sure that when it context switches us back in, it23 * honours the fact that we had PMAE clear.24 *25 * Observed to hit the failing case on the first EBB with a broken kernel.26 */27 28static bool mmcr0_mismatch;29static uint64_t before, after;30 31static void syscall_ebb_callee(void)32{33 uint64_t val;34 35 val = mfspr(SPRN_BESCR);36 if (!(val & BESCR_PMEO)) {37 ebb_state.stats.spurious++;38 goto out;39 }40 41 ebb_state.stats.ebb_count++;42 count_pmc(1, sample_period);43 44 before = mfspr(SPRN_MMCR0);45 46 /* Try and get ourselves scheduled, to force a PMU context switch */47 sched_yield();48 49 after = mfspr(SPRN_MMCR0);50 if (before != after)51 mmcr0_mismatch = true;52 53out:54 reset_ebb();55}56 57static int test_body(void)58{59 struct event event;60 61 SKIP_IF(!ebb_is_supported());62 63 event_init_named(&event, 0x1001e, "cycles");64 event_leader_ebb_init(&event);65 66 event.attr.exclude_kernel = 1;67 event.attr.exclude_hv = 1;68 event.attr.exclude_idle = 1;69 70 FAIL_IF(event_open(&event));71 72 setup_ebb_handler(syscall_ebb_callee);73 ebb_global_enable();74 75 FAIL_IF(ebb_event_enable(&event));76 77 mtspr(SPRN_PMC1, pmc_sample_period(sample_period));78 79 while (ebb_state.stats.ebb_count < 20 && !mmcr0_mismatch)80 FAIL_IF(core_busy_loop());81 82 ebb_global_disable();83 ebb_freeze_pmcs();84 85 dump_ebb_state();86 87 if (mmcr0_mismatch)88 printf("Saw MMCR0 before 0x%lx after 0x%lx\n", before, after);89 90 event_close(&event);91 92 FAIL_IF(ebb_state.stats.ebb_count == 0);93 FAIL_IF(mmcr0_mismatch);94 95 return 0;96}97 98int pmae_handling(void)99{100 return eat_cpu(test_body);101}102 103int main(void)104{105 return test_harness(pmae_handling, "pmae_handling");106}107