change syscall-sign-extend test

don't use SYS_clock_gettime because raw syscall is not time64 safe,
use a SYS_read which likely works across various abis without issues.

diff --git a/src/regression/syscall-sign-extend.c b/src/regression/syscall-sign-extend.c
index 7d3e0d8..ea47ab3 100644 (file)
--- a/src/regression/syscall-sign-extend.c
+++ b/src/regression/syscall-sign-extend.c
@@ -1,44 +1,26 @@
 // commit 5f95f965e933c5b155db75520ac27c92ddbcf400 2014-03-18
 // syscall should not sign extend pointers on x32
 #define _GNU_SOURCE
-#include <string.h>
 #include <errno.h>
-#include <unistd.h>
-#include <time.h>
+#include <fcntl.h>
+#include <string.h>
 #include <sys/syscall.h>
+#include <unistd.h>
 #include "test.h"
 
-#define T(f) ((f) && (t_error(#f " failed: %s\n", strerror(errno)), 0))
-
-static unsigned long long tsdiff(struct timespec ts2, struct timespec ts)
-{
-       if (ts2.tv_nsec < ts.tv_nsec) {
-               ts2.tv_nsec += 1000000000;
-               ts2.tv_sec--;
-       }
-       if (ts2.tv_sec < ts.tv_sec) {
-               t_error("non-monotonic SYS_clock_gettime vs clock_gettime: %llu ns\n",
-                       (ts.tv_sec - ts2.tv_sec)*1000000000ULL + ts.tv_nsec - ts2.tv_nsec);
-               return 0;
-       }
-       return (ts2.tv_sec - ts.tv_sec)*1000000000ULL + (ts2.tv_nsec - ts.tv_nsec);
-}
+#define T(f) (!(f) && (t_error(#f " failed: %s\n", strerror(errno)), 0))
 
 int main(void)
 {
-       struct timespec ts, ts2;
-       unsigned long long diff;
+       char buf[1] = {1};
+       int fd;
+       int r;
 
        // test syscall with pointer
-       T(syscall(SYS_clock_gettime, CLOCK_REALTIME, &ts));
-
-       // check if timespec is filled correctly
-       T(clock_gettime(CLOCK_REALTIME, &ts2));
-       // adjust because linux vdso is non-monotonic wrt the syscall..
-       ts.tv_nsec += 2;
-       diff = tsdiff(ts2, ts);
-       if (diff > 5 * 1000000000ULL)
-               t_error("large diff between clock_gettime calls: %llu ns\n", diff);
+       T((fd = open("/dev/zero", O_RDONLY)) >= 0);
+       T((r = syscall(SYS_read, fd, buf, 1)) == 1);
+       if (buf[0] != 0)
+               t_error("read %d instead of 0\n", buf[0]);
 
        return t_status;
 }