1 #include <inttypes.h>
2 #include <stdio.h>
3 #include <stdlib.h>
4 #include <signal.h>
5 #include "tests/sys_mman.h"
6 
7 void sig_handler(int sig){
8   int var;
9   fprintf(stderr, "caught signal, local var is on %#" PRIxPTR "\n",
10           (uintptr_t)&var);
11 }
12 
13 int main(int argv, char** argc) {
14   int res, i;
15   stack_t sigstk;
16   struct sigaction act;
17   static const int size = SIGSTKSZ*2;
18   // We give EXEC permissions because this won't work on ppc32 unless you
19   // ask for an alt stack with EXEC permissions,
20   // since signal returning requires execution of code on the stack.
21   char *stk = (char *)mmap(0, size, PROT_READ|PROT_WRITE|PROT_EXEC,
22                                     MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
23   sigstk.ss_sp = stk;
24 
25   sigstk.ss_size = size;
26   sigstk.ss_flags = 0;
27   fprintf(stderr, "calling sigaltstack, stack base is %#" PRIxPTR "\n",
28           (uintptr_t)sigstk.ss_sp);
29   if (sigaltstack(&sigstk,0)<0) perror("sigaltstack");
30 
31   fprintf(stderr,"setting sigaction\n");
32   act.sa_flags=SA_ONSTACK;
33   act.sa_handler=&sig_handler;
34   sigemptyset(&act.sa_mask);
35   res = sigaction(SIGUSR1,&act,0);
36   fprintf(stderr, "res = %d\n", res);
37   fprintf(stderr, "raising the signal\n");
38   raise(SIGUSR1);
39 
40   /* Loop long enough so valgrind has a forced context switch and
41      actually delivers the signal before the thread exits. */
42   for (i = 0; i < 1000000; i++) ;
43 
44   fprintf(stderr, "done\n");
45   return 0;
46 }
47