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/* Test if rflags values are correctly propagated in and out of a signal
handler. Note that we actually test only the propagation of the overflow
and sign flags. */
#include <assert.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/regset.h>
#include <sys/syscall.h>
#include <sys/ucontext.h>
#define OBIT(rflags) (!!((rflags) & (1 << 11)))
#define SBIT(rflags) (!!((rflags) & (1 << 7)))
static siginfo_t si;
static ucontext_t uc;
static void sighandler(int sig, siginfo_t *sip, void *arg)
{
si = *sip;
uc = *((ucontext_t *) arg);
}
int main(void)
{
struct sigaction sa;
pid_t pid;
long rflags;
sa.sa_sigaction = sighandler;
sa.sa_flags = SA_SIGINFO;
if (sigfillset(&sa.sa_mask)) {
perror("sigfillset");
return 1;
}
if (sigaction(SIGUSR1, &sa, NULL)) {
perror("sigaction");
return 1;
}
pid = getpid();
__asm__ __volatile__(
/* Set overflow and sign flags. */
"movl $1, %%edx\n"
"addl $0x7fffffff, %%edx\n"
/* Trigger the signal handler. */
"syscall\n"
"pushfq\n"
"popq %%rdx\n"
: "=d" (rflags)
: "a" (SYS_kill), "D" (pid), "S" (SIGUSR1)
: "cc", "memory");
printf("Values in the signal handler:\n");
printf(" overflow=%d, sign=%d\n",
OBIT(uc.uc_mcontext.gregs[REG_RFL]),
SBIT(uc.uc_mcontext.gregs[REG_RFL]));
printf("Values after the return from the signal handler:\n");
printf(" overflow=%d, sign=%d\n", OBIT(rflags), SBIT(rflags));
return 0;
}
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