linux-kernel - Re: [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page

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Message-ID: <20200131155150.GD22482@gate.crashing.org>
Date:   Fri, 31 Jan 2020 09:51:50 -0600
From:   Segher Boessenkool <segher@...nel.crashing.org>
To:     Christophe Leroy <christophe.leroy@....fr>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page

On Fri, Jan 31, 2020 at 03:37:34PM +0000, Christophe Leroy wrote:
> When the range is a single page, do a page flush instead.

> +	start &= PAGE_MASK;
> +	end = (end - 1) | ~PAGE_MASK;
>  	if (!Hash) {
> -		_tlbia();
> +		if (end - start == PAGE_SIZE)
> +			_tlbie(start);
> +		else
> +			_tlbia();
>  		return;
>  	}

For just one page, you get  end - start == 0  actually?


Segher