linux-kernel - Re: [PATCH v2 1/2] MIPS: Set page access bit with pgprot on platforms with RIXI

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Message-ID: <20200726083206.GE5032@alpha.franken.de>
Date:   Sun, 26 Jul 2020 10:32:06 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Bibo Mao <maobibo@...ngson.cn>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Paul Burton <paulburton@...nel.org>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2 1/2] MIPS: Set page access bit with pgprot on
 platforms with RIXI

On Sat, Jun 06, 2020 at 12:02:48PM +0800, Bibo Mao wrote:
> @@ -158,23 +158,23 @@ void __update_cache(unsigned long address, pte_t pte)
>  static inline void setup_protection_map(void)
>  {
>  	if (cpu_has_rixi) {
> -		protection_map[0]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
> -		protection_map[1]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
> -		protection_map[2]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
> -		protection_map[3]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
> -		protection_map[4]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -		protection_map[5]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -		protection_map[6]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -		protection_map[7]  = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -
> -		protection_map[8]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
> -		protection_map[9]  = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC);
> -		protection_map[10] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | _PAGE_NO_READ);
> -		protection_map[11] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE);
> -		protection_map[12] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -		protection_map[13] = __pgprot(_page_cachable_default | _PAGE_PRESENT);
> -		protection_map[14] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE);
> -		protection_map[15] = __pgprot(_page_cachable_default | _PAGE_PRESENT | _PAGE_WRITE);
> +		protection_map[0]  = __pgprot(__PC | __PP | __NX | __NR);
> +		protection_map[1]  = __pgprot(__PC | __PP | __NX | ___R);
> +		protection_map[2]  = __pgprot(__PC | __PP | __NX | __NR);
> +		protection_map[3]  = __pgprot(__PC | __PP | __NX | ___R);
> +		protection_map[4]  = __pgprot(__PC | __PP | ___R);
> +		protection_map[5]  = __pgprot(__PC | __PP | ___R);
> +		protection_map[6]  = __pgprot(__PC | __PP | ___R);
> +		protection_map[7]  = __pgprot(__PC | __PP | ___R);
> +
> +		protection_map[8]  = __pgprot(__PC | __PP | __NX | __NR);
> +		protection_map[9]  = __pgprot(__PC | __PP | __NX | ___R);
> +		protection_map[10] = __pgprot(__PC | __PP | __NX | ___W | __NR);
> +		protection_map[11] = __pgprot(__PC | __PP | __NX | ___W | ___R);
> +		protection_map[12] = __pgprot(__PC | __PP | ___R);
> +		protection_map[13] = __pgprot(__PC | __PP | ___R);
> +		protection_map[14] = __pgprot(__PC | __PP | ___W | ___R);
> +		protection_map[15] = __pgprot(__PC | __PP | ___W | ___R);

you are doing two steps in one go, so it's not obvious you are not only
using some macros, but also changing semantics. And while there are already
really long lines, please leave it that way and only do the access bit
change.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]