cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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back_to_back_ebbs_test.c (2199B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright 2014, Michael Ellerman, IBM Corp.
      4 */
      5
      6#include <stdbool.h>
      7#include <stdio.h>
      8#include <stdlib.h>
      9
     10#include "ebb.h"
     11
     12
     13#define NUMBER_OF_EBBS	50
     14
     15/*
     16 * Test that if we overflow the counter while in the EBB handler, we take
     17 * another EBB on exiting from the handler.
     18 *
     19 * We do this by counting with a stupidly low sample period, causing us to
     20 * overflow the PMU while we're still in the EBB handler, leading to another
     21 * EBB.
     22 *
     23 * We get out of what would otherwise be an infinite loop by leaving the
     24 * counter frozen once we've taken enough EBBs.
     25 */
     26
     27static void ebb_callee(void)
     28{
     29	uint64_t siar, val;
     30
     31	val = mfspr(SPRN_BESCR);
     32	if (!(val & BESCR_PMEO)) {
     33		ebb_state.stats.spurious++;
     34		goto out;
     35	}
     36
     37	ebb_state.stats.ebb_count++;
     38	trace_log_counter(ebb_state.trace, ebb_state.stats.ebb_count);
     39
     40	/* Resets the PMC */
     41	count_pmc(1, sample_period);
     42
     43out:
     44	if (ebb_state.stats.ebb_count == NUMBER_OF_EBBS)
     45		/* Reset but leave counters frozen */
     46		reset_ebb_with_clear_mask(MMCR0_PMAO);
     47	else
     48		/* Unfreezes */
     49		reset_ebb();
     50
     51	/* Do some stuff to chew some cycles and pop the counter */
     52	siar = mfspr(SPRN_SIAR);
     53	trace_log_reg(ebb_state.trace, SPRN_SIAR, siar);
     54
     55	val = mfspr(SPRN_PMC1);
     56	trace_log_reg(ebb_state.trace, SPRN_PMC1, val);
     57
     58	val = mfspr(SPRN_MMCR0);
     59	trace_log_reg(ebb_state.trace, SPRN_MMCR0, val);
     60}
     61
     62int back_to_back_ebbs(void)
     63{
     64	struct event event;
     65
     66	SKIP_IF(!ebb_is_supported());
     67
     68	event_init_named(&event, 0x1001e, "cycles");
     69	event_leader_ebb_init(&event);
     70
     71	event.attr.exclude_kernel = 1;
     72	event.attr.exclude_hv = 1;
     73	event.attr.exclude_idle = 1;
     74
     75	FAIL_IF(event_open(&event));
     76
     77	setup_ebb_handler(ebb_callee);
     78
     79	FAIL_IF(ebb_event_enable(&event));
     80
     81	sample_period = 5;
     82
     83	ebb_freeze_pmcs();
     84	mtspr(SPRN_PMC1, pmc_sample_period(sample_period));
     85	ebb_global_enable();
     86	ebb_unfreeze_pmcs();
     87
     88	while (ebb_state.stats.ebb_count < NUMBER_OF_EBBS)
     89		FAIL_IF(core_busy_loop());
     90
     91	ebb_global_disable();
     92	ebb_freeze_pmcs();
     93
     94	dump_ebb_state();
     95
     96	event_close(&event);
     97
     98	FAIL_IF(ebb_state.stats.ebb_count != NUMBER_OF_EBBS);
     99
    100	return 0;
    101}
    102
    103int main(void)
    104{
    105	return test_harness(back_to_back_ebbs, "back_to_back_ebbs");
    106}