ARC: pt_regs update #1: Align pt_regs end with end of kernel stack page
Historically, pt_regs would end at offset of 1 word from end of stack
page.
----------------- -> START of page (task->stack)
| |
| thread_info |
-----------------
| |
^ ~ ~
| ~ ~
| | |
| | | <---- pt_regs used to END here
-----------------
| 1 word GUTTER |
----------------- -> End of page (START of kernel stack)
This required special "one-off" considerations in low level code.
The root cause is very likely assumption of "empty" SP by the original
ARC kernel hackers, despite ARC700 always been "full" SP.
So finally RIP one word gutter !
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 5f26b2c..81efbca 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -50,7 +50,7 @@
unsigned long thread_saved_pc(struct task_struct *t);
#define task_pt_regs(p) \
- ((struct pt_regs *)(THREAD_SIZE - 4 + (void *)task_stack_page(p)) - 1)
+ ((struct pt_regs *)(THREAD_SIZE + (void *)task_stack_page(p)) - 1)
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while (0)