[PATCH 3/3] vmcore: Convert read_from_oldmem() to take an iov_iter

[Christoph Hellwig]

>  
>  ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
>  {
> -	return read_from_oldmem(buf, count, ppos, 0,
> +	struct kvec kvec = { .iov_base = buf, .iov_len = count };
> +	struct iov_iter iter;
> +
> +	iov_iter_kvec(&iter, READ, &kvec, 1, count);
> +
> +	return read_from_oldmem(&iter, count, ppos,
>  				cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
>  }

elfcorehdr_read should probably also take an iov_iter while we're at it.

I also don't quite understand why we even need the arch overrides for it,
but that would require some digging into the history of this interface.