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Message-ID: <54FE8C79.2000104@codesourcery.com>
Date: Tue, 10 Mar 2015 14:17:29 +0800
From: Chung-Lin Tang <cltang@codesourcery.com>
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To: Ley Foon Tan <lftan@altera.com>,
        Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
CC: Chung-Lin Tang <chunglin.tang@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
        Tobias Klauser <tklauser@distanz.ch>,
        Walter Goossens <waltergoossens@home.nl>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        "nios2-dev@lists.rocketboards.org" <nios2-dev@lists.rocketboards.org>,
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Subject: Re: nios2: is the ptrace ABI correct?
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On 2015/3/10 10:54 AM, Ley Foon Tan wrote:
> On Tue, Mar 10, 2015 at 1:05 AM, Ezequiel Garcia
> <ezequiel@vanguardiasur.com.ar> wrote:
>>
>>
>> On 03/09/2015 02:02 PM, Chung-Lin Tang wrote:
>>> On 2015/3/10 12:54 AM, Chung-Lin Tang wrote:
>>>> It appears that some of the ways nios2 has organized the
>>>> ucontext/pt_regs/etc. are remnants of the pre-generic code, some
>>>> basically because the port was based off m68k.
>>>>
>>>> I've re-organized the headers a bit: nios2/include/asm/ucontext.h is
>>>> deleted, and re-definition of struct sigcontext now allows use of
>>>> uapi/asm-generic/ucontext.h directly.  Note that the reorg, despite
>>>> effectively renaming some fields, is still binary compatible. I'll
>>>> probably update the corresponding glibc definitions later.
>>>>
>>>> struct pt_regs is now not exported, and all exported register sets are
>>>> now supposed to follow the 49 register set defined as in GDB now.
>>>>
>>>> Tobias, Ley Foon, how do you think this looks?
>>>
>>> Sorry, accidentally attached unrelated GCC patch instead, this one's the
>>> correct one.
>>>
>>
>> Looks good. I'm wondering if...
>>
>> +/* User structures for general purpose registers.  */
>> +struct user_pt_regs {
>> +       __u32           regs[49];
>>  };
>>
>> Can we expose the registers explicitly here? Like this:
>>
>> struct user_pt_regs {
>>         __u32 r0;
>>         __u32 r1;
>>         ...
>>         __u32 sp;
>>         __u32 gp;
>>         __u32 estatus;
>> };
>>
>> It looks self-documenting and thus easier to use.
> 
> Hi Chung-Lin,
> 
> Your patch look good to me.
> Do you have any problem to change the struct user_pt_regs based on
> Ezequiel's suggestion?

Well, exposing the register names like that sort of defeats the purpose of
the PTR_* defines.

Judging from the overall trend of style in arch/*/include/uapi/asm/ptrace.h
across ports, I would prefer to stay with the array field.

Thanks,
Chung-Lin