Re: [Qemu-devel] [PATCH] SH: Fix struct target_stat64 for 64bit host

[michael <trimarchi@gandalf.sssup.it>]

takasi-y@ops.dti.ne.jp wrote:
> Hi,
>
>   
>> I have some trouble using the qemu emulator on the x86_64 host system. 
>> The system emulate
>> an qemu-sh4 machine. I try to fix it without success:
>>     
>
> I found stat64 has damaged return address on stack because of bloated
>  struct stat64.
>
> On sh4 target, struct target_stat64 has "unsigned int" as its member.
> It may results unwanted struct layout on 64bit host. Switched to abi_ulong.
> We also have to use packed attribute for sh4, because the struct has
> unaligned 64bit member st_size.
>
>  Signed-off-by: Takashi YOSHII <takasi-y@ops.dti.ne.jp>
>
> ---
>  linux-user/syscall_defs.h |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index 5a58010..01e48fd 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -1475,15 +1475,15 @@ struct target_stat {
>  /* This matches struct stat64 in glibc2.1, hence the absolutely
>   * insane amounts of padding around dev_t's.
>   */
> -struct target_stat64 {
> +struct __attribute__((__packed__)) target_stat64 {
>  	unsigned long long	st_dev;
>   
Define it packets assecure me that each type occopies the exact dimension
>  	unsigned char	__pad0[4];
>  
>  #define TARGET_STAT64_HAS_BROKEN_ST_INO	1
>  	abi_ulong	__st_ino;
>  
> -	unsigned int	st_mode;
> -	unsigned int	st_nlink;
> +	abi_ulong	st_mode;
> +	abi_ulong	st_nlink;
>   
The size of an unsigned int is 4 byte and is ok? Why this change?
>  
>  	abi_ulong	st_uid;
>  	abi_ulong	st_gid;
>   

Regards Michael