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