tools/testing/selftests/x86/test_vdso.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * ldt_gdt.c - Test cases for LDT and GDT access
   4  * Copyright (c) 2011-2015 Andrew Lutomirski
   5  */
   6
   7 #define _GNU_SOURCE
   8
   9 #include <stdio.h>
  10 #include <sys/time.h>
  11 #include <time.h>
  12 #include <stdlib.h>
  13 #include <unistd.h>
  14 #include <sys/syscall.h>
  15 #include <dlfcn.h>
  16 #include <string.h>
  17 #include <errno.h>
  18 #include <sched.h>
  19 #include <stdbool.h>
  20
  21 #ifndef SYS_getcpu
  22 # ifdef __x86_64__
  23 #  define SYS_getcpu 309
  24 # else
  25 #  define SYS_getcpu 318
  26 # endif
  27 #endif
  28
  29 /* max length of lines in /proc/self/maps - anything longer is skipped here */
  30 #define MAPS_LINE_LEN 128
  31
  32 int nerrs = 0;
  33
  34 typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
  35
  36 getcpu_t vgetcpu;
  37 getcpu_t vdso_getcpu;
  38
  39 static void *vsyscall_getcpu(void)
  40 {
  41 #ifdef __x86_64__
  42         FILE *maps;
  43         char line[MAPS_LINE_LEN];
  44         bool found = false;
  45
  46         maps = fopen("/proc/self/maps", "r");
  47         if (!maps) /* might still be present, but ignore it here, as we test vDSO not vsyscall */
  48                 return NULL;
  49
  50         while (fgets(line, MAPS_LINE_LEN, maps)) {
  51                 char r, x;
  52                 void *start, *end;
  53                 char name[MAPS_LINE_LEN];
  54
  55                 /* sscanf() is safe here as strlen(name) >= strlen(line) */
  56                 if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
  57                            &start, &end, &r, &x, name) != 5)
  58                         continue;
  59
  60                 if (strcmp(name, "[vsyscall]"))
  61                         continue;
  62
  63                 /* assume entries are OK, as we test vDSO here not vsyscall */
  64                 found = true;
  65                 break;
  66         }
  67
  68         fclose(maps);
  69
  70         if (!found) {
  71                 printf("Warning: failed to find vsyscall getcpu\n");
  72                 return NULL;
  73         }
  74         return (void *) (0xffffffffff600800);
  75 #else
  76         return NULL;
  77 #endif
  78 }
  79
  80
  81 static void fill_function_pointers()
  82 {
  83         void *vdso = dlopen("linux-vdso.so.1",
  84                             RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
  85         if (!vdso)
  86                 vdso = dlopen("linux-gate.so.1",
  87                               RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
  88         if (!vdso) {
  89                 printf("[WARN]\tfailed to find vDSO\n");
  90                 return;
  91         }
  92
  93         vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
  94         if (!vdso_getcpu)
  95                 printf("Warning: failed to find getcpu in vDSO\n");
  96
  97         vgetcpu = (getcpu_t) vsyscall_getcpu();
  98 }
  99
 100 static long sys_getcpu(unsigned * cpu, unsigned * node,
 101                        void* cache)
 102 {
 103         return syscall(__NR_getcpu, cpu, node, cache);
 104 }
 105
 106 static void test_getcpu(void)
 107 {
 108         printf("[RUN]\tTesting getcpu...\n");
 109
 110         for (int cpu = 0; ; cpu++) {
 111                 cpu_set_t cpuset;
 112                 CPU_ZERO(&cpuset);
 113                 CPU_SET(cpu, &cpuset);
 114                 if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
 115                         return;
 116
 117                 unsigned cpu_sys, cpu_vdso, cpu_vsys,
 118                         node_sys, node_vdso, node_vsys;
 119                 long ret_sys, ret_vdso = 1, ret_vsys = 1;
 120                 unsigned node;
 121
 122                 ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
 123                 if (vdso_getcpu)
 124                         ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
 125                 if (vgetcpu)
 126                         ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
 127
 128                 if (!ret_sys)
 129                         node = node_sys;
 130                 else if (!ret_vdso)
 131                         node = node_vdso;
 132                 else if (!ret_vsys)
 133                         node = node_vsys;
 134
 135                 bool ok = true;
 136                 if (!ret_sys && (cpu_sys != cpu || node_sys != node))
 137                         ok = false;
 138                 if (!ret_vdso && (cpu_vdso != cpu || node_vdso != node))
 139                         ok = false;
 140                 if (!ret_vsys && (cpu_vsys != cpu || node_vsys != node))
 141                         ok = false;
 142
 143                 printf("[%s]\tCPU %u:", ok ? "OK" : "FAIL", cpu);
 144                 if (!ret_sys)
 145                         printf(" syscall: cpu %u, node %u", cpu_sys, node_sys);
 146                 if (!ret_vdso)
 147                         printf(" vdso: cpu %u, node %u", cpu_vdso, node_vdso);
 148                 if (!ret_vsys)
 149                         printf(" vsyscall: cpu %u, node %u", cpu_vsys,
 150                                node_vsys);
 151                 printf("\n");
 152
 153                 if (!ok)
 154                         nerrs++;
 155         }
 156 }
 157
 158 int main(int argc, char **argv)
 159 {
 160         fill_function_pointers();
 161
 162         test_getcpu();
 163
 164         return nerrs ? 1 : 0;
 165 }