LXR linux/tools/testing/selftests/powerpc/signal/sigreturn

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Test that we can take signals with and without the VDSO mapped, which trigger
   4 * different paths in the signal handling code.
   5 *
   6 * See handle_rt_signal64() and setup_trampoline() in signal_64.c
   7 */
   8
   9#define _GNU_SOURCE
  10
  11#include <errno.h>
  12#include <stdio.h>
  13#include <signal.h>
  14#include <stdlib.h>
  15#include <string.h>
  16#include <sys/mman.h>
  17#include <sys/types.h>
  18#include <unistd.h>
  19
  20// Ensure assert() is not compiled out
  21#undef NDEBUG
  22#include <assert.h>
  23
  24#include "utils.h"
  25
  26static int search_proc_maps(char *needle, unsigned long *low, unsigned long *high)
  27{
  28        unsigned long start, end;
  29        static char buf[4096];
  30        char name[128];
  31        FILE *f;
  32        int rc = -1;
  33
  34        f = fopen("/proc/self/maps", "r");
  35        if (!f) {
  36                perror("fopen");
  37                return -1;
  38        }
  39
  40        while (fgets(buf, sizeof(buf), f)) {
  41                rc = sscanf(buf, "%lx-%lx %*c%*c%*c%*c %*x %*d:%*d %*d %127s\n",
  42                            &start, &end, name);
  43                if (rc == 2)
  44                        continue;
  45
  46                if (rc != 3) {
  47                        printf("sscanf errored\n");
  48                        rc = -1;
  49                        break;
  50                }
  51
  52                if (strstr(name, needle)) {
  53                        *low = start;
  54                        *high = end - 1;
  55                        rc = 0;
  56                        break;
  57                }
  58        }
  59
  60        fclose(f);
  61
  62        return rc;
  63}
  64
  65static volatile sig_atomic_t took_signal = 0;
  66
  67static void sigusr1_handler(int sig)
  68{
  69        took_signal++;
  70}
  71
  72int test_sigreturn_vdso(void)
  73{
  74        unsigned long low, high, size;
  75        struct sigaction act;
  76        char *p;
  77
  78        act.sa_handler = sigusr1_handler;
  79        act.sa_flags = 0;
  80        sigemptyset(&act.sa_mask);
  81
  82        assert(sigaction(SIGUSR1, &act, NULL) == 0);
  83
  84        // Confirm the VDSO is mapped, and work out where it is
  85        assert(search_proc_maps("[vdso]", &low, &high) == 0);
  86        size = high - low + 1;
  87        printf("VDSO is at 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
  88
  89        kill(getpid(), SIGUSR1);
  90        assert(took_signal == 1);
  91        printf("Signal delivered OK with VDSO mapped\n");
  92
  93        // Remap the VDSO somewhere else
  94        p = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
  95        assert(p != MAP_FAILED);
  96        assert(mremap((void *)low, size, size, MREMAP_MAYMOVE|MREMAP_FIXED, p) != MAP_FAILED);
  97        assert(search_proc_maps("[vdso]", &low, &high) == 0);
  98        size = high - low + 1;
  99        printf("VDSO moved to 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
 100
 101        kill(getpid(), SIGUSR1);
 102        assert(took_signal == 2);
 103        printf("Signal delivered OK with VDSO moved\n");
 104
 105        assert(munmap((void *)low, size) == 0);
 106        printf("Unmapped VDSO\n");
 107
 108        // Confirm the VDSO is not mapped anymore
 109        assert(search_proc_maps("[vdso]", &low, &high) != 0);
 110
 111        // Make the stack executable
 112        assert(search_proc_maps("[stack]", &low, &high) == 0);
 113        size = high - low + 1;
 114        mprotect((void *)low, size, PROT_READ|PROT_WRITE|PROT_EXEC);
 115        printf("Remapped the stack executable\n");
 116
 117        kill(getpid(), SIGUSR1);
 118        assert(took_signal == 3);
 119        printf("Signal delivered OK with VDSO unmapped\n");
 120
 121        return 0;
 122}
 123
 124int main(void)
 125{
 126        return test_harness(test_sigreturn_vdso, "sigreturn_vdso");
 127}
 128