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The rfi_flush and entry_flush selftests work by using the PM_LD_MISS_L1 perf event to count L1D misses. The value of this event has changed over time: - Power7 uses 0x400f0 - Power8 and Power9 use both 0x400f0 and 0x3e054 - Power10 uses only 0x3e054 Rather than relying on raw values, configure perf to count L1D read misses in the most explicit way available. This fixes the selftests to work on systems without 0x400f0 as PM_LD_MISS_L1, and should change no behaviour for systems that the tests already worked on. The only potential downside is that referring to a specific perf event requires PMU support implemented in the kernel for that platform. Signed-off-by: Russell Currey <ruscur@russell.cc> Acked-by: Daniel Axtens <dja@axtens.net> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210223070227.2916871-1-ruscur@russell.cc
143 lines
3.4 KiB
C
143 lines
3.4 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright 2018 IBM Corporation.
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*/
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#define __SANE_USERSPACE_TYPES__
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#include <sys/types.h>
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#include <stdint.h>
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#include <malloc.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "utils.h"
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#include "flush_utils.h"
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int rfi_flush_test(void)
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{
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char *p;
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int repetitions = 10;
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int fd, passes = 0, iter, rc = 0;
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struct perf_event_read v;
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__u64 l1d_misses_total = 0;
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unsigned long iterations = 100000, zero_size = 24 * 1024;
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unsigned long l1d_misses_expected;
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int rfi_flush_orig, rfi_flush;
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int have_entry_flush, entry_flush_orig;
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SKIP_IF(geteuid() != 0);
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// The PMU event we use only works on Power7 or later
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SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));
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if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
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perror("Unable to read powerpc/rfi_flush debugfs file");
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SKIP_IF(1);
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}
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if (read_debugfs_file("powerpc/entry_flush", &entry_flush_orig) < 0) {
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have_entry_flush = 0;
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} else {
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have_entry_flush = 1;
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if (entry_flush_orig != 0) {
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if (write_debugfs_file("powerpc/entry_flush", 0) < 0) {
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perror("error writing to powerpc/entry_flush debugfs file");
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return 1;
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}
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}
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}
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rfi_flush = rfi_flush_orig;
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fd = perf_event_open_counter(PERF_TYPE_HW_CACHE, PERF_L1D_READ_MISS_CONFIG, -1);
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FAIL_IF(fd < 0);
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p = (char *)memalign(zero_size, CACHELINE_SIZE);
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FAIL_IF(perf_event_enable(fd));
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// disable L1 prefetching
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set_dscr(1);
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iter = repetitions;
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/*
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* We expect to see l1d miss for each cacheline access when rfi_flush
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* is set. Allow a small variation on this.
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*/
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l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);
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again:
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FAIL_IF(perf_event_reset(fd));
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syscall_loop(p, iterations, zero_size);
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FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));
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if (rfi_flush && v.l1d_misses >= l1d_misses_expected)
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passes++;
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else if (!rfi_flush && v.l1d_misses < (l1d_misses_expected / 2))
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passes++;
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l1d_misses_total += v.l1d_misses;
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while (--iter)
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goto again;
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if (passes < repetitions) {
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printf("FAIL (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d failures]\n",
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rfi_flush, l1d_misses_total, rfi_flush ? '<' : '>',
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rfi_flush ? repetitions * l1d_misses_expected :
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repetitions * l1d_misses_expected / 2,
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repetitions - passes, repetitions);
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rc = 1;
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} else
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printf("PASS (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d pass]\n",
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rfi_flush, l1d_misses_total, rfi_flush ? '>' : '<',
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rfi_flush ? repetitions * l1d_misses_expected :
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repetitions * l1d_misses_expected / 2,
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passes, repetitions);
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if (rfi_flush == rfi_flush_orig) {
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rfi_flush = !rfi_flush_orig;
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if (write_debugfs_file("powerpc/rfi_flush", rfi_flush) < 0) {
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perror("error writing to powerpc/rfi_flush debugfs file");
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return 1;
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}
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iter = repetitions;
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l1d_misses_total = 0;
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passes = 0;
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goto again;
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}
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perf_event_disable(fd);
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close(fd);
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set_dscr(0);
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if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_orig) < 0) {
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perror("unable to restore original value of powerpc/rfi_flush debugfs file");
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return 1;
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}
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if (have_entry_flush) {
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if (write_debugfs_file("powerpc/entry_flush", entry_flush_orig) < 0) {
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perror("unable to restore original value of powerpc/entry_flush "
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"debugfs file");
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return 1;
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}
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}
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return rc;
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}
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int main(int argc, char *argv[])
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{
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return test_harness(rfi_flush_test, "rfi_flush_test");
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}
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