Quelle  uaccess_flush.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0+

/*
 * Copyright 2018 IBM Corporation.
 * Copyright 2020 Canonical Ltd.
 */

#define __SANE_USERSPACE_TYPES__

#include <sys/types.h>
#include <stdint.h>
#include <malloc.h>
#include <unistd.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "utils.h"
#include "flush_utils.h"

int uaccess_flush_test(void)
{
 char *p;
 int repetitions = 10;
 int fd, passes = 0, iter, rc = 0;
 struct perf_event_read v;
 __u64 l1d_misses_total = 0;
 unsigned long iterations = 100000, zero_size = 24 * 1024;
 unsigned long l1d_misses_expected;
 int rfi_flush_orig;
 int entry_flush_orig;
 int uaccess_flush, uaccess_flush_orig;

 SKIP_IF(geteuid() != 0);

 // The PMU event we use only works on Power7 or later
 SKIP_IF(!have_hwcap(PPC_FEATURE_ARCH_2_06));

 if (read_debugfs_int("powerpc/rfi_flush", &rfi_flush_orig) < 0) {
  perror("Unable to read powerpc/rfi_flush debugfs file");
  SKIP_IF(1);
 }

 if (read_debugfs_int("powerpc/entry_flush", &entry_flush_orig) < 0) {
  perror("Unable to read powerpc/entry_flush debugfs file");
  SKIP_IF(1);
 }

 if (read_debugfs_int("powerpc/uaccess_flush", &uaccess_flush_orig) < 0) {
  perror("Unable to read powerpc/entry_flush debugfs file");
  SKIP_IF(1);
 }

 if (rfi_flush_orig != 0) {
  if (write_debugfs_int("powerpc/rfi_flush", 0) < 0) {
   perror("error writing to powerpc/rfi_flush debugfs file");
   FAIL_IF(1);
  }
 }

 if (entry_flush_orig != 0) {
  if (write_debugfs_int("powerpc/entry_flush", 0) < 0) {
   perror("error writing to powerpc/entry_flush debugfs file");
   FAIL_IF(1);
  }
 }

 uaccess_flush = uaccess_flush_orig;

 fd = perf_event_open_counter(PERF_TYPE_HW_CACHE, PERF_L1D_READ_MISS_CONFIG, -1);
 FAIL_IF(fd < 0);

 p = (char *)memalign(zero_size, CACHELINE_SIZE);

 FAIL_IF(perf_event_enable(fd));

 // disable L1 prefetching
 set_dscr(1);

 iter = repetitions;

 /*
 * We expect to see l1d miss for each cacheline access when entry_flush
 * is set. Allow a small variation on this.
 */
 l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);

again:
 FAIL_IF(perf_event_reset(fd));

 syscall_loop_uaccess(p, iterations, zero_size);

 FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));

 if (uaccess_flush && v.l1d_misses >= l1d_misses_expected)
  passes++;
 else if (!uaccess_flush && v.l1d_misses < (l1d_misses_expected / 2))
  passes++;

 l1d_misses_total += v.l1d_misses;

 while (--iter)
  goto again;

 if (passes < repetitions) {
  printf("FAIL (L1D misses with uaccess_flush=%d: %llu %c %lu) [%d/%d failures]\n",
         uaccess_flush, l1d_misses_total, uaccess_flush ? '<' : '>',
         uaccess_flush ? repetitions * l1d_misses_expected :
         repetitions * l1d_misses_expected / 2,
         repetitions - passes, repetitions);
  rc = 1;
 } else {
  printf("PASS (L1D misses with uaccess_flush=%d: %llu %c %lu) [%d/%d pass]\n",
         uaccess_flush, l1d_misses_total, uaccess_flush ? '>' : '<',
         uaccess_flush ? repetitions * l1d_misses_expected :
         repetitions * l1d_misses_expected / 2,
         passes, repetitions);
 }

 if (uaccess_flush == uaccess_flush_orig) {
  uaccess_flush = !uaccess_flush_orig;
  if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush) < 0) {
   perror("error writing to powerpc/uaccess_flush debugfs file");
   return 1;
  }
  iter = repetitions;
  l1d_misses_total = 0;
  passes = 0;
  goto again;
 }

 perf_event_disable(fd);
 close(fd);

 set_dscr(0);

 if (write_debugfs_int("powerpc/rfi_flush", rfi_flush_orig) < 0) {
  perror("unable to restore original value of powerpc/rfi_flush debugfs file");
  return 1;
 }

 if (write_debugfs_int("powerpc/entry_flush", entry_flush_orig) < 0) {
  perror("unable to restore original value of powerpc/entry_flush debugfs file");
  return 1;
 }

 if (write_debugfs_int("powerpc/uaccess_flush", uaccess_flush_orig) < 0) {
  perror("unable to restore original value of powerpc/uaccess_flush debugfs file");
  return 1;
 }

 return rc;
}

int main(int argc, char *argv[])
{
 return test_harness(uaccess_flush_test, "uaccess_flush_test");
}