File: faultstatus.c

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/* 
   Check that a fault signal handler gets the expected info
 */
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <setjmp.h>
#include "tests/sys_mman.h"
#include <unistd.h>

/* Division by zero triggers a SIGFPE on x86 and x86_64,
   but not on the PowerPC architecture.

   On ARM-Linux, we do get a SIGFPE, but not from the faulting of a
   division instruction (there isn't any such thing) but rather
   because the process exits via tgkill, sending itself a SIGFPE.
   Hence we get a SIGFPE but the SI_CODE is different from that on
   x86/amd64-linux.
 */
#if defined(__powerpc__) || defined(__aarch64__)
#  define DIVISION_BY_ZERO_TRIGGERS_FPE 0
#  define DIVISION_BY_ZERO_SI_CODE      SI_TKILL
#elif defined(__arm__)
#  define DIVISION_BY_ZERO_TRIGGERS_FPE 1
#  define DIVISION_BY_ZERO_SI_CODE      SI_TKILL
#else
#  define DIVISION_BY_ZERO_TRIGGERS_FPE 1
#  define DIVISION_BY_ZERO_SI_CODE      FPE_INTDIV
#endif

/* Accessing non-mapped virtual address results in SIGBUS
 * with si_code equal to BUS_ADRERR on Linux, whereas in SIGBUS
 * with si_code equal to BUS_OBJERR on Solaris. On Solaris,
 * BUS_ADRERR is used for bus time out while BUS_OBJERR is translated
 * from underlying codes FC_OBJERR (x86) or ASYNC_BERR (sparc).
 */
#if defined(VGO_solaris)
#  define BUS_ERROR_SI_CODE  BUS_OBJERR
#else
#  define BUS_ERROR_SI_CODE  BUS_ADRERR
#endif

struct test {
	void (*test)(void);
	int sig;
	int code;
	volatile void *addr;
};

static const struct test *cur_test;

static int zero();

static sigjmp_buf escape;

#define BADADDR	((int *)0x1234)

#define FILESIZE	(4*__pagesize)
#define MAPSIZE		(2*FILESIZE)
static unsigned int __pagesize;
static char volatile *volatile mapping;

static int testsig(int sig, int want)
{
	if (sig != want) {
		fprintf(stderr, "  FAIL: expected signal %d, not %d\n", want, sig);
		return 0;
	} 
	return 1;
}

static int testcode(int code, int want)
{
	if (code != want) {
		fprintf(stderr, "  FAIL: expected si_code==%d, not %d\n", want, code);
		return 0;
	}
	return 1;
}

static int testaddr(void *addr, volatile void *want)
{
	/* Some architectures (e.g. s390) just provide enough information to
         resolve the page fault, but do not provide the offset within a page */
#if defined(__s390__)
	if (addr != (void *) ((unsigned long) want & ~0xffful)) {
#else
	if (addr != want) {
#endif
		fprintf(stderr, "  FAIL: expected si_addr==%p, not %p\n", want, addr);
		return 0;
	}
	return 1;

}

static void handler(int sig, siginfo_t *si, void *uc)
{
	int ok = 1;

	ok = ok && testsig(sig, cur_test->sig);
	ok = ok && testcode(si->si_code, cur_test->code);
	if (cur_test->addr)
		ok = ok && testaddr(si->si_addr, cur_test->addr);

	if (ok)
		fprintf(stderr, "  PASS\n");

	siglongjmp(escape, ok + 1);
}


static void test1(void)
{
	*BADADDR = 'x';
}

static void test2()
{
	mapping[0] = 'x';
}

static void test3()
{
	mapping[FILESIZE+10];
}

static void test4()
{
	volatile int v = 44/zero();

	(void)v;
#if DIVISION_BY_ZERO_TRIGGERS_FPE == 0
	raise(SIGFPE);
#endif
}

int main()
{
	int fd, i;
	static const int sigs[] = { SIGSEGV, SIGILL, SIGBUS, SIGFPE, SIGTRAP };
	struct sigaction sa;
	__pagesize = (unsigned int)sysconf(_SC_PAGE_SIZE);
	sa.sa_sigaction = handler;
	sa.sa_flags = SA_SIGINFO;
	sigfillset(&sa.sa_mask);
	
	for(i = 0; i < sizeof(sigs)/sizeof(*sigs); i++)
		sigaction(sigs[i], &sa, NULL);

	/* we need O_RDWR for the truncate below */
	fd = open("faultstatus.tmp", O_CREAT|O_TRUNC|O_EXCL|O_RDWR, 0600);
	if (fd == -1) {
		perror("tmpfile");
		exit(1);
	}
	unlink("faultstatus.tmp");
	ftruncate(fd, FILESIZE);

	mapping = mmap(0, MAPSIZE, PROT_READ, MAP_PRIVATE, fd, 0);
	close(fd);

	{
		const struct test tests[] = {
#define T(n, sig, code, addr) { test##n, sig, code, addr }
			T(1, SIGSEGV,	SEGV_MAPERR,	BADADDR),
			T(2, SIGSEGV,	SEGV_ACCERR,	mapping),
			T(3, SIGBUS,	BUS_ERROR_SI_CODE, &mapping[FILESIZE+10]),
			T(4, SIGFPE,    DIVISION_BY_ZERO_SI_CODE, 0),
#undef T
		};

		for(i = 0; i < sizeof(tests)/sizeof(*tests); i++) {
			cur_test = &tests[i];
		
			if (sigsetjmp(escape, 1) == 0) {
				fprintf(stderr, "Test %d: ", i+1);
				tests[i].test();
				fprintf(stderr, "  FAIL: no fault, or handler returned\n");
			}
		}
	}

	return 0;
}

static int zero()
{
	return 0;
}