linux-user: clock_nanosleep errno Handling on PPC

The clock_nanosleep syscall is unusual in that it returns positive
numbers in error handling situations, versus returning -1 and setting
errno, or returning a negative errno value.  On POWER, the kernel will
set the SO bit of CR0 to indicate failure in a syscall.  QEMU has
generic handling to do this for syscalls with standard return values.

Add special case code for clock_nanosleep to handle CR0 properly.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

linux-user/syscall.c

@@ -9033,6 +9033,14 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
         ret = get_errno(clock_nanosleep(arg1, arg2, &ts, arg4 ? &ts : NULL));
         if (arg4)
             host_to_target_timespec(arg4, &ts);
+
+#if defined(TARGET_PPC)
+        /* clock_nanosleep is odd in that it returns positive errno values.
+         * On PPC, CR0 bit 3 should be set in such a situation. */
+        if (ret) {
+            ((CPUPPCState *)cpu_env)->crf[0] |= 1;
+        }
+#endif
         break;
     }
 #endif