Re: [PATCH 1/6] GenWQE PCI support, health monitoring and recovery

[Arnd Bergmann]

On Tuesday 03 December 2013, Frank Haverkamp wrote:
> Ohh, sorry __u64 of course:
> 
> /* common struct for chip image exchange */
> struct genwqe_bitstream {
>         __u64 data_addr;                /* pointer to image data */
>         __u32 size;                     /* size of image file */
>         __u32 crc;                      /* crc of this image */
>         __u8  partition;                /* '0', '1', or 'v' */
>         __u64 target_addr;              /* starting address in Flash */
>         __u8  uid;                      /* 1=host/x=dram */
> 
>         __u64 slu_id;                   /* informational/sim: SluID */
>         __u64 app_id;                   /* informational/sim: AppID */
> 
>         __u16 retc;                     /* returned from processing */
>         __u16 attn;                     /* attention code from
> processing */
>         __u32 progress;                 /* progress code from processing
> */
> };
> 
> and than I do in my userspace application:
> 
>         load.data_addr = (unsigned long)buf;
> 
> Is that ok, or must I consider more?
> 

I haven't followed the recent discussions, jumping into the middle here:
The structure above is not safe for a generic ioctl interface because it
has different padding on x86-32 and x86-64, where __u64 has different
alignment.

You can try to avoid the implicit padding by sorting the members by size,
by making some members larger or by adding explicit padding.

	Arnd
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