/* 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; }