1/* Test if values in rax, rbx, rcx, rdx, rsi and rdi are correctly propagated
2   into and out of a signal handler and also check that the same applies for
3   uninitialised values and their origins. */
4
5#include <assert.h>
6#include <signal.h>
7#include <stdio.h>
8#include <stdlib.h>
9#include <unistd.h>
10#include <sys/regset.h>
11#include <sys/syscall.h>
12#include <sys/ucontext.h>
13
14static siginfo_t si;
15static ucontext_t uc;
16/* x0 is always zero, but is visible to Valgrind as uninitialised. */
17static long x0;
18
19void break_out(void);
20
21static void sighandler(int sig, siginfo_t *sip, void *arg)
22{
23   ucontext_t *ucp = (ucontext_t *) arg;
24
25   si = *sip;
26   uc = *ucp;
27
28   ucp->uc_mcontext.gregs[REG_RCX] = x0;
29
30   /* Break out of the endless loop. */
31   *(uintptr_t*)&ucp->uc_mcontext.gregs[REG_RIP] = (uintptr_t)break_out;
32}
33
34int main(void)
35{
36   struct sigaction sa;
37   long rax, rbx, rcx, rdx, rsi, rdi;
38   long y0;
39
40   /* Uninitialised, but we know px[0] is 0x0. */
41   long *px = malloc(sizeof(*px));
42   x0 = px[0];
43
44   /* Uninitialised, but we know py[0] is 0x0. */
45   long *py = malloc(sizeof(*py));
46   y0 = py[0];
47
48   sa.sa_sigaction = sighandler;
49   sa.sa_flags = SA_SIGINFO;
50   if (sigfillset(&sa.sa_mask)) {
51      perror("sigfillset");
52      return 1;
53   }
54   if (sigaction(SIGALRM, &sa, NULL)) {
55      perror("sigaction");
56      return 1;
57   }
58
59   alarm(2);
60
61   __asm__ __volatile__(
62      /* Set values in general purpose registers. */
63      "movq   $0xf0, %%rax\n"
64      "movq   %[y0], %%rbx\n"
65      "movq   $0xf1, %%rcx\n"
66      "movq   $0xf2, %%rdx\n"
67      "movq   $0xf3, %%rsi\n"
68      "movq   $0xf4, %%rdi\n"
69
70      /* Loopity loop, this is where the SIGALRM is triggered. */
71      "1:\n"
72      "jmp    1b\n"
73
74      "break_out:\n"
75      : "=a" (rax), "=b" (rbx), "=c" (rcx), "=d" (rdx), "=S" (rsi),
76        "=D" (rdi)
77      : [y0] "m" (y0)
78      : "cc", "memory");
79
80   printf("Values in the signal handler:\n");
81   printf("  rax=%#lx, rcx=%#lx, rdx=%#lx, rsi=%#lx, rdi=%#lx\n",
82          uc.uc_mcontext.gregs[REG_RAX], uc.uc_mcontext.gregs[REG_RCX],
83          uc.uc_mcontext.gregs[REG_RDX], uc.uc_mcontext.gregs[REG_RSI],
84          uc.uc_mcontext.gregs[REG_RDI]);
85   /* Check that rbx contains an uninitialised value (origin is py[0]). */
86   if (uc.uc_mcontext.gregs[REG_RBX])
87      assert(0);
88
89   printf("Values after the return from the signal handler:\n");
90   printf("  rax=%#lx, rdx=%#lx, rsi=%#lx, rdi=%#lx\n", rax, rdx, rsi, rdi);
91   /* Check that rbx and rcx contain uninitialised values (origin is py[0]
92      and px[0], respectively). */
93   if (rbx || rcx)
94      assert(0);
95
96   return 0;
97}
98
99