[Qemu-ppc] [V3 PATCH 11/13] linux-user: clock_nanosleep errno Handling on PPC

[Tom Musta]

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 <address@hidden>
Reviewed-by: Peter Maydell <address@hidden>
---
V2: Eliminated redundant "#if defined" condition per Peter Maydell's
review.

 linux-user/syscall.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a20c2f7..fc828ae 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8999,6 +8999,14 @@ 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
-- 
1.7.1