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From: Richard Henderson <richard.henderson@linaro.org>
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Date: Fri, 15 Sep 2017 10:13:06 -0700
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Subject: Re: [Qemu-devel] [PATCH] linux-user/syscall.c: Handle SH4's
 exceptional alignment for p{read, write}64
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To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= <f4bug@amsat.org>, James Clarke <jrtc27@jrtc27.com>, QEMU Developers <qemu-devel@nongnu.org>, Laurent Vivier <laurent@vivier.eu>
Cc: Peter Maydell <peter.maydell@linaro.org>, John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

On 09/15/2017 08:41 AM, Philippe Mathieu-Daudé wrote:
> On 09/15/2017 03:58 AM, James Clarke wrote:
>> Fixes: https://bugs.launchpad.net/qemu/+bug/1716767
>> Signed-off-by: James Clarke <jrtc27@jrtc27.com>
> 
> Congratulations! You have won yourself a R: entry (Designated reviewer) in the
> "Linux user" and "SH4" sections of MAINTAINERS!
> 
>> ---
>>   linux-user/syscall.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> index 9b6364a266..24d6a81c21 100644
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -10495,20 +10495,32 @@ abi_long do_syscall(void *cpu_env, int num,
>> abi_long arg1,
>>   #endif
>>   #ifdef TARGET_NR_pread64
>>       case TARGET_NR_pread64:
>> +#if defined(TARGET_SH4)
>> +        /* SH4 doesn't align register pairs, except for p{read,write}64 */
>> +        arg4 = arg5;
>> +        arg5 = arg6;
>> +#else
>>           if (regpairs_aligned(cpu_env)) {
>>               arg4 = arg5;
>>               arg5 = arg6;
>>           }
>> +#endif
> 
> I'd rather use arch_type from "sysemu/arch_init.h":
> 
>   case TARGET_NR_pwrite64:
>       /* SH4 doesn't align register pairs, except for p{read,write}64 */
>       if (arch_type == QEMU_ARCH_SH4 || regpairs_aligned(cpu_env)) {
>           arg4 = arg5;
>           arg5 = arg6;
>       }
> 
> What do you think?

I'd rather change the interface of regpairs_aligned to take the syscall number,
and add an instance for SH4 above.


r~