openrisc: pass correct arg to schedule_tail

schedule_tail() requires that the 'prev' task be passed as an argument
to it.  This arg is set in _switch, just before 'returning' to one of
the ret_* functions where schedule_tail is invoked.

Signed-off-by: Jonas Bonn <jonas@southpole.se>

2 files changed, 7 insertions, 3 deletions

diff --git a/arch/openrisc/kernel/entry.S b/arch/openrisc/kernel/entry.S
index ddfcaa828b0e..374e63e7c9f6 100644
--- a/arch/openrisc/kernel/entry.S
+++ b/arch/openrisc/kernel/entry.S
@@ -1044,8 +1044,13 @@ ENTRY(_switch)
         /* Unwind stack to pre-switch state */
         l.addi  r1,r1,(INT_FRAME_SIZE)
 
-        /* Return via the link-register back to where we 'came from', where that can be
-         * either schedule() or return_from_fork()... */
+        /* Return via the link-register back to where we 'came from', where
+         * that may be either schedule(), ret_from_fork(), or
+         * ret_from_kernel_thread().  If we are returning to a new thread,
+         * we are expected to have set up the arg to schedule_tail already,
+         * hence we do so here unconditionally:
+         */
+        l.lwz   r3,TI_STACK(r3)         /* Load 'prev' as schedule_tail arg */
         l.jr    r9
          l.nop
 
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index c35f3ab1a8d3..ad26d5af2649 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -165,7 +165,6 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
          * the kernel stack.
          */
         kregs->sp = top_of_kernel_stack;
-        kregs->gpr[3] = (unsigned long)current; /* arg to schedule_tail */
         kregs->gpr[10] = (unsigned long)task_thread_info(p);
         kregs->gpr[9] = (unsigned long)ret_from_fork;