[CRIU] [PATCH 4/5] vdso: parasite -- Prepare new vdso mark structure.

[Pavel Emelyanov]

On 06/06/2014 06:07 PM, Cyrill Gorcunov wrote:

> @@ -78,26 +84,38 @@ static inline unsigned long vdso_vma_size(struct vdso_symtable *t)
>   */
>  struct vdso_mark {
>  	u64			signature;
> -	unsigned long		proxy_addr;
> -};
> +	unsigned long		proxy_vdso_addr;
> +
> +	unsigned long		version;

This is write-only variable.

>  
> +	/*
> +	 * In case of new vDSO format the VVAR area address
> +	 * neeed for easier discovering where it lives without
> +	 * relying on procfs output.
> +	 */

How do we distinguish 3 cases from each other:

1. Old kernel w/o vvar area
2. New kernel with vvar area
3. New kernel with vvar area and error in its detection

?

> +	unsigned long		proxy_vvar_addr;
> +};
>  /* Magic number (criuvdso) */
>  #define VDSO_MARK_SIGNATURE	(0x6f73647675697263ULL)

This signature is no longer in use in the code. Why?

> +#define VDSO_MARK_SIGNATURE_V2	(0x4f53447675697263ULL)	/* Magic number (criuvDSO) */

Can we make these comments to be placed in one manner?

>  
>  static inline bool is_vdso_mark(void *addr)
>  {
>  	struct vdso_mark *m = addr;
>  
> -	return m->signature == VDSO_MARK_SIGNATURE &&
> -		m->proxy_addr != VDSO_BAD_ADDR;
> +	return (m->signature == VDSO_MARK_SIGNATURE_V2 ||
> +		m->signature == VDSO_MARK_SIGNATURE) &&
> +		m->proxy_vdso_addr != VDSO_BAD_ADDR;
>  }
>  
> -static inline void vdso_put_mark(void *where, unsigned long proxy_addr)
> +static inline void vdso_put_mark(void *where, unsigned long proxy_vdso_addr, unsigned long proxy_vvar_addr)