[PATCH] mn10300: Fix crash just after starting userspace on !CONFIG_PREEMPT

From: David Howells
Date: Tue Sep 10 2013 - 12:42:47 EST



From: Akira Takeuchi <takeuchi.akr@xxxxxxxxxxxxxxxx>

Kernel crashes just after starting userspace programs, if CONFIG_PREEMPT is
disabled.

Freeing unused kernel memory: 96K (90286000 - 9029e000)
MISALIGN: 97c33ff9: unsupported instruction f
MISALIGN: 97c33ff9: unsupported instruction f
MISALIGN: 97c33ff9: unsupported instruction f
:

This commit fix the problem. It was introduced by the commit d17fc238ac14
(MN10300: Enable IRQs more in system call exit work path).

Signed-off-by: Akira Takeuchi <takeuchi.akr@xxxxxxxxxxxxxxxx>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@xxxxxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
arch/mn10300/kernel/entry.S | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/arch/mn10300/kernel/entry.S b/arch/mn10300/kernel/entry.S
index 222152a..177d61d 100644
--- a/arch/mn10300/kernel/entry.S
+++ b/arch/mn10300/kernel/entry.S
@@ -171,10 +171,10 @@ ret_from_intr:
mov (REG_EPSW,fp),d0 # need to deliver signals before
# returning to userspace
and EPSW_nSL,d0
- beq resume_kernel # returning to supervisor mode
+ bne resume_userspace # returning to userspace

#ifdef CONFIG_PREEMPT
-ENTRY(resume_kernel)
+resume_kernel:
LOCAL_IRQ_DISABLE
mov (TI_preempt_count,a2),d0 # non-zero preempt_count ?
cmp 0,d0
@@ -189,6 +189,8 @@ need_resched:
bne restore_all
call preempt_schedule_irq[],0
jmp need_resched
+#else
+ jmp resume_kernel
#endif


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