* [Alpha/Linux ] Stack layout/and register values for ret_from_sys_call
@ 2001-12-17 18:20 Aneesh Kumar K.V
2001-12-29 0:07 ` Richard Henderson
0 siblings, 1 reply; 2+ messages in thread
From: Aneesh Kumar K.V @ 2001-12-17 18:20 UTC (permalink / raw)
To: linux-kernel
Hi,
Can someone explain me what should be the stack layout and register
value( if there is any restriction ) before calling ret_from_syscall for
Alpha. Again in entry.S i find may places where we make current (
Register 8) as below
lda $8,0x3fff
bic $30,$8,$8
If someone can expain what happens in the above two assembly statement
it will be really helpful.
Thanks in advance.
-aneesh
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* Re: [Alpha/Linux ] Stack layout/and register values for ret_from_sys_call
2001-12-17 18:20 [Alpha/Linux ] Stack layout/and register values for ret_from_sys_call Aneesh Kumar K.V
@ 2001-12-29 0:07 ` Richard Henderson
0 siblings, 0 replies; 2+ messages in thread
From: Richard Henderson @ 2001-12-29 0:07 UTC (permalink / raw)
To: Aneesh Kumar K.V; +Cc: linux-kernel
On Mon, Dec 17, 2001 at 11:50:57PM +0530, Aneesh Kumar K.V wrote:
> Can someone explain me what should be the stack layout and register
> value( if there is any restriction ) before calling ret_from_syscall for
> Alpha.
Top of stack should contain a struct pt_regs. See asm/ptrace.h.
> lda $8,0x3fff
> bic $30,$8,$8
>
> If someone can expain what happens in the above two assembly statement
> it will be really helpful.
This computes the value for "current". The stack plus task structure
is aligned on a two-page boundary. See task_union in linux/sched.h.
r~
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2001-12-17 18:20 [Alpha/Linux ] Stack layout/and register values for ret_from_sys_call Aneesh Kumar K.V
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