tools/nolibc: fall back to sys_clock_gettime() in gettimeofday()

Newer architectures (like riscv32) do not implement sys_gettimeofday().
In those cases fall back to sys_clock_gettime().
While that does not support the timezone argument of sys_gettimeofday(),
specifying this argument invokes undefined behaviour, so it's safe to ignore.

Signed-off-by: Thomas Weißschuh <[e-mail]>
Acked-by: Willy Tarreau <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Thomas Weißschuh <[e-mail]>

tools/include/nolibc/sys/time.h

···
 #include "../arch.h"
 #include "../sys.h"
 
+static int sys_clock_gettime(clockid_t clockid, struct timespec *tp);
+
 /*
  * int gettimeofday(struct timeval *tv, struct timezone *tz);
  */
···
 #ifdef __NR_gettimeofday
 	return my_syscall2(__NR_gettimeofday, tv, tz);
 #else
-	return __nolibc_enosys(__func__, tv, tz);
+	(void) tz; /* Non-NULL tz is undefined behaviour */
+
+	struct timespec tp;
+	int ret;
+
+	ret = sys_clock_gettime(CLOCK_REALTIME, &tp);
+	if (!ret && tv) {
+		tv->tv_sec = tp.tv_sec;
+		tv->tv_usec = tp.tv_nsec / 1000;
+	}
+
+	return ret;
 #endif
 }