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// SPDX-License-Identifier: GPL-2.0
/*
* Test that we can take signals with and without the VDSO mapped, which trigger
* different paths in the signal handling code.
*
* See handle_rt_signal64() and setup_trampoline() in signal_64.c
*/
#define _GNU_SOURCE
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
// Ensure assert() is not compiled out
#undef NDEBUG
#include <assert.h>
#include "utils.h"
static int search_proc_maps(char *needle, unsigned long *low, unsigned long *high)
{
unsigned long start, end;
static char buf[4096];
char name[128];
FILE *f;
int rc = -1;
f = fopen("/proc/self/maps", "r");
if (!f) {
perror("fopen");
return -1;
}
while (fgets(buf, sizeof(buf), f)) {
rc = sscanf(buf, "%lx-%lx %*c%*c%*c%*c %*x %*d:%*d %*d %127s\n",
&start, &end, name);
if (rc == 2)
continue;
if (rc != 3) {
printf("sscanf errored\n");
rc = -1;
break;
}
if (strstr(name, needle)) {
*low = start;
*high = end - 1;
rc = 0;
break;
}
}
fclose(f);
return rc;
}
static volatile sig_atomic_t took_signal = 0;
static void sigusr1_handler(int sig)
{
took_signal++;
}
int test_sigreturn_vdso(void)
{
unsigned long low, high, size;
struct sigaction act;
char *p;
act.sa_handler = sigusr1_handler;
act.sa_flags = 0;
sigemptyset(&act.sa_mask);
assert(sigaction(SIGUSR1, &act, NULL) == 0);
// Confirm the VDSO is mapped, and work out where it is
assert(search_proc_maps("[vdso]", &low, &high) == 0);
size = high - low + 1;
printf("VDSO is at 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
kill(getpid(), SIGUSR1);
assert(took_signal == 1);
printf("Signal delivered OK with VDSO mapped\n");
// Remap the VDSO somewhere else
p = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
assert(p != MAP_FAILED);
assert(mremap((void *)low, size, size, MREMAP_MAYMOVE|MREMAP_FIXED, p) != MAP_FAILED);
assert(search_proc_maps("[vdso]", &low, &high) == 0);
size = high - low + 1;
printf("VDSO moved to 0x%lx-0x%lx (%lu bytes)\n", low, high, size);
kill(getpid(), SIGUSR1);
assert(took_signal == 2);
printf("Signal delivered OK with VDSO moved\n");
assert(munmap((void *)low, size) == 0);
printf("Unmapped VDSO\n");
// Confirm the VDSO is not mapped anymore
assert(search_proc_maps("[vdso]", &low, &high) != 0);
// Make the stack executable
assert(search_proc_maps("[stack]", &low, &high) == 0);
size = high - low + 1;
mprotect((void *)low, size, PROT_READ|PROT_WRITE|PROT_EXEC);
printf("Remapped the stack executable\n");
kill(getpid(), SIGUSR1);
assert(took_signal == 3);
printf("Signal delivered OK with VDSO unmapped\n");
return 0;
}
int main(void)
{
return test_harness(test_sigreturn_vdso, "sigreturn_vdso");
}
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