Subject: Re: [RFC v7 02/25] powerpc: track allocation status of all pkeys

From: Thiago Jung Bauermann <[email-masked]>
Date: Thu, 10 Aug 2017 17:25:39 -0300

Ram Pai <[email-masked]> writes:
>  static inline void pkey_initialize(void)
>  {
> +	int os_reserved, i;
> +
>  	/* disable the pkey system till everything
>  	 * is in place. A patch further down the
>  	 * line will enable it.
>  	 */
>  	pkey_inited = false;
> +
> +	/* Lets assume 32 keys */
> +	pkeys_total = 32;
> +
> +#ifdef CONFIG_PPC_4K_PAGES
> +	/*
> +	 * the OS can manage only 8 pkeys
> +	 * due to its inability to represent
> +	 * them in the linux 4K-PTE.
> +	 */
> +	os_reserved = pkeys_total-8;
> +#else
> +	os_reserved = 0;
> +#endif
> +	/*
> +	 * Bits are in LE format.
> +	 * NOTE: 1, 0 are reserved.
> +	 * key 0 is the default key, which allows read/write/execute.
> +	 * key 1 is recommended not to be used.
> +	 * PowerISA(3.0) page 1015, programming note.
> +	 */
> +	initial_allocation_mask = ~0x0;
> +	for (i = 2; i < (pkeys_total - os_reserved); i++)
> +		initial_allocation_mask &= ~(0x1<<i);
>  }
>  #endif /*_ASM_PPC64_PKEYS_H */

In v6, key 31 was also reserved, but it's not in this version. Is this
intentional?

Isn't it better for this function to be in pkeys.c? Ideally, functions
should be in .c files not in headers unless they're very small or
performance sensitive IMHO.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center