root/tools/testing/selftests/powerpc/security/rfi_flush.c

DEFINITIONS

1. load
2. syscall_loop
3. rfi_flush_test
4. main

   1 // SPDX-License-Identifier: GPL-2.0+
   2 
   3 /*
   4  * Copyright 2018 IBM Corporation.
   5  */
   6 
   7 #define __SANE_USERSPACE_TYPES__
   8 
   9 #include <sys/types.h>
  10 #include <stdint.h>
  11 #include <malloc.h>
  12 #include <unistd.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <stdio.h>
  16 #include "utils.h"
  17 
  18 #define CACHELINE_SIZE 128
  19 
  20 struct perf_event_read {
  21         __u64 nr;
  22         __u64 l1d_misses;
  23 };
  24 
  25 static inline __u64 load(void *addr)
  26 {
  27         __u64 tmp;
  28 
  29         asm volatile("ld %0,0(%1)" : "=r"(tmp) : "b"(addr));
  30 
  31         return tmp;
  32 }
  33 
  34 static void syscall_loop(char *p, unsigned long iterations,
  35                          unsigned long zero_size)
  36 {
  37         for (unsigned long i = 0; i < iterations; i++) {
  38                 for (unsigned long j = 0; j < zero_size; j += CACHELINE_SIZE)
  39                         load(p + j);
  40                 getppid();
  41         }
  42 }
  43 
  44 int rfi_flush_test(void)
  45 {
  46         char *p;
  47         int repetitions = 10;
  48         int fd, passes = 0, iter, rc = 0;
  49         struct perf_event_read v;
  50         __u64 l1d_misses_total = 0;
  51         unsigned long iterations = 100000, zero_size = 24 * 1024;
  52         unsigned long l1d_misses_expected;
  53         int rfi_flush_org, rfi_flush;
  54 
  55         SKIP_IF(geteuid() != 0);
  56 
  57         if (read_debugfs_file("powerpc/rfi_flush", &rfi_flush_org)) {
  58                 perror("Unable to read powerpc/rfi_flush debugfs file");
  59                 SKIP_IF(1);
  60         }
  61 
  62         rfi_flush = rfi_flush_org;
  63 
  64         fd = perf_event_open_counter(PERF_TYPE_RAW, /* L1d miss */ 0x400f0, -1);
  65         FAIL_IF(fd < 0);
  66 
  67         p = (char *)memalign(zero_size, CACHELINE_SIZE);
  68 
  69         FAIL_IF(perf_event_enable(fd));
  70 
  71         set_dscr(1);
  72 
  73         iter = repetitions;
  74 
  75         /*
  76          * We expect to see l1d miss for each cacheline access when rfi_flush
  77          * is set. Allow a small variation on this.
  78          */
  79         l1d_misses_expected = iterations * (zero_size / CACHELINE_SIZE - 2);
  80 
  81 again:
  82         FAIL_IF(perf_event_reset(fd));
  83 
  84         syscall_loop(p, iterations, zero_size);
  85 
  86         FAIL_IF(read(fd, &v, sizeof(v)) != sizeof(v));
  87 
  88         if (rfi_flush && v.l1d_misses >= l1d_misses_expected)
  89                 passes++;
  90         else if (!rfi_flush && v.l1d_misses < (l1d_misses_expected / 2))
  91                 passes++;
  92 
  93         l1d_misses_total += v.l1d_misses;
  94 
  95         while (--iter)
  96                 goto again;
  97 
  98         if (passes < repetitions) {
  99                 printf("FAIL (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d failures]\n",
 100                        rfi_flush, l1d_misses_total, rfi_flush ? '<' : '>',
 101                        rfi_flush ? repetitions * l1d_misses_expected :
 102                        repetitions * l1d_misses_expected / 2,
 103                        repetitions - passes, repetitions);
 104                 rc = 1;
 105         } else
 106                 printf("PASS (L1D misses with rfi_flush=%d: %llu %c %lu) [%d/%d pass]\n",
 107                        rfi_flush, l1d_misses_total, rfi_flush ? '>' : '<',
 108                        rfi_flush ? repetitions * l1d_misses_expected :
 109                        repetitions * l1d_misses_expected / 2,
 110                        passes, repetitions);
 111 
 112         if (rfi_flush == rfi_flush_org) {
 113                 rfi_flush = !rfi_flush_org;
 114                 if (write_debugfs_file("powerpc/rfi_flush", rfi_flush) < 0) {
 115                         perror("error writing to powerpc/rfi_flush debugfs file");
 116                         return 1;
 117                 }
 118                 iter = repetitions;
 119                 l1d_misses_total = 0;
 120                 passes = 0;
 121                 goto again;
 122         }
 123 
 124         perf_event_disable(fd);
 125         close(fd);
 126 
 127         set_dscr(0);
 128 
 129         if (write_debugfs_file("powerpc/rfi_flush", rfi_flush_org) < 0) {
 130                 perror("unable to restore original value of powerpc/rfi_flush debugfs file");
 131                 return 1;
 132         }
 133 
 134         return rc;
 135 }
 136 
 137 int main(int argc, char *argv[])
 138 {
 139         return test_harness(rfi_flush_test, "rfi_flush_test");
 140 }