linux-kernel - Re: [PATCH] MIPS: vdso: Utilize __pa() for gic

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Date:   Mon, 11 Jul 2022 10:38:13 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     linux-mips@...r.kernel.org, Greg Ungerer <gerg@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] MIPS: vdso: Utilize __pa() for gic_pfn

On Thu, Jul 07, 2022 at 01:27:58PM -0700, Florian Fainelli wrote:
> The GIC user offset is mapped into every process' virtual address and is
> therefore part of the hot-path of arch_setup_additional_pages(). Utilize
> __pa() such that we are more optimal even when CONFIG_DEBUG_VIRTUAL is
> enabled, and while at it utilize PFN_DOWN() instead of open-coding the
> right shift by PAGE_SHIFT.
> 
> Reported-by: Greg Ungerer <gerg@...nel.org>
> Suggested-by: Serge Semin <fancer.lancer@...il.com>
> Fixes: dfad83cb7193 ("MIPS: Add support for CONFIG_DEBUG_VIRTUAL")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  arch/mips/kernel/vdso.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
> index 3d0cf471f2fe..b2cc2c2dd4bf 100644
> --- a/arch/mips/kernel/vdso.c
> +++ b/arch/mips/kernel/vdso.c
> @@ -159,7 +159,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
>  	/* Map GIC user page. */
>  	if (gic_size) {
>  		gic_base = (unsigned long)mips_gic_base + MIPS_GIC_USER_OFS;
> -		gic_pfn = virt_to_phys((void *)gic_base) >> PAGE_SHIFT;
> +		gic_pfn = PFN_DOWN(__pa(gic_base));
>  
>  		ret = io_remap_pfn_range(vma, base, gic_pfn, gic_size,
>  					 pgprot_noncached(vma->vm_page_prot));
> -- 
> 2.25.1

applied to mips-next.

Thomas.

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