memcheck/tests/x86-solaris/context_eflags2.c

/* x86 variant of the amd64-solaris/context_rflags2.c test. */

#include <assert.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/ucontext.h>

#define OBIT(eflags) (!!((eflags) & (1 << 11)))
#define SBIT(eflags) (!!((eflags) & (1 << 7)))

static siginfo_t si;
static ucontext_t uc;

void break_out(void);

static void sighandler(int sig, siginfo_t *sip, ucontext_t *ucp)
{
   si = *sip;
   uc = *ucp;

   /* Break out of the endless loop. */
   *(uintptr_t*)&ucp->uc_mcontext.gregs[EIP] = (uintptr_t)break_out;
}

int main(void)
{
   struct sigaction sa;
   int eflags;
   int x1;

   /* Uninitialised, but we know px[0] is 0x0. */
   int *px = malloc(sizeof(*px));
   x1 = px[0] + 1;

   sa.sa_handler = sighandler;
   sa.sa_flags = SA_SIGINFO;
   if (sigfillset(&sa.sa_mask)) {
      perror("sigfillset");
      return 1;
   }
   if (sigaction(SIGALRM, &sa, NULL)) {
      perror("sigaction");
      return 1;
   }

   alarm(2);

   __asm__ __volatile__(
      /* Set overflow and sign flags. */
      "movl   %[x1], %%edx\n"
      "addl   $0x7fffffff, %%edx\n"

      /* Loopity loop, this is where the SIGALRM is triggered. */
      "1:\n"
      "jmp    1b\n"

      "break_out:\n"
      "pushfl\n"
      "popl   %%edx\n"
      : "=d" (eflags)
      : [x1] "m" (x1)
      : "cc", "memory");

   /* Check that the overflow and sign flags are uninitialised.

      Note: This actually fails because the eflags are only approximate
      (always initialised) in the signal handler. */
   if (!OBIT(uc.uc_mcontext.gregs[EFL]) || !SBIT(uc.uc_mcontext.gregs[EFL]))
      assert(0);

   /* Check that the overflow and sign flags are uninitialised. */
   if (!OBIT(eflags) || !SBIT(eflags))
      assert(0);

   return 0;
}