ARC: pt_regs update #1: Align pt_regs end with end of kernel stack page
authorVineet Gupta <vgupta@synopsys.com>
Tue, 28 May 2013 04:04:45 +0000 (09:34 +0530)
committerVineet Gupta <vgupta@synopsys.com>
Sat, 22 Jun 2013 13:53:21 +0000 (19:23 +0530)
commit283237a04fd332bddc2ac298e6ad7d23a1fc4b99
tree227d6d2d2c2b167fb75df1835b466ed160a7994f
parentbed30976e7f1077c105306597ef05895234ba600
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>
arch/arc/include/asm/entry.h
arch/arc/include/asm/processor.h
arch/arc/include/asm/ptrace.h
arch/arc/kernel/process.c