[SPARC64]: Move syscall success and newchild state out of thread flags.

These two bits were accesses non-atomically from assembler
code.  So, in order to eliminate any potential races resulting
from that, move these pieces of state into two bytes elsewhere
in struct thread_info.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 9 deletions

diff --git a/arch/sparc64/kernel/entry.S b/arch/sparc64/kernel/entry.S
index d781f10adc52..88332f00094a 100644
--- a/arch/sparc64/kernel/entry.S
+++ b/arch/sparc64/kernel/entry.S
@@ -1600,11 +1600,11 @@ sys_clone:	flushw
                 ba,pt           %xcc, sparc_do_fork
                  add            %sp, PTREGS_OFF, %o2
 ret_from_syscall:
-                /* Clear SPARC_FLAG_NEWCHILD, switch_to leaves thread.flags in
-                 * %o7 for us.  Check performance counter stuff too.
+                /* Clear current_thread_info()->new_child, and
+                 * check performance counter stuff too.
                  */
-                andn            %o7, _TIF_NEWCHILD, %l0
-                stx             %l0, [%g6 + TI_FLAGS]
+                stb             %g0, [%g6 + TI_NEW_CHILD]
+                ldx             [%g6 + TI_FLAGS], %l0
                 call            schedule_tail
                  mov            %g7, %o0
                 andcc           %l0, _TIF_PERFCTR, %g0
@@ -1720,12 +1720,11 @@ ret_sys_call:
         /* Check if force_successful_syscall_return()
          * was invoked.
          */
-        ldx             [%curptr + TI_FLAGS], %l0
-        andcc           %l0, _TIF_SYSCALL_SUCCESS, %g0
-        be,pt           %icc, 1f
-         andn           %l0, _TIF_SYSCALL_SUCCESS, %l0
+        ldub            [%curptr + TI_SYS_NOERROR], %l0
+        brz,pt          %l0, 1f
+         nop
         ba,pt           %xcc, 80f
-         stx            %l0, [%curptr + TI_FLAGS]
+         stb            %g0, [%curptr + TI_SYS_NOERROR]
 
 1:
         cmp             %o0, -ERESTART_RESTARTBLOCK