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

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Date:   Fri, 8 Jul 2022 11:58:50 +1000
From:   Greg Ungerer <gerg@...nel.org>
To:     Florian Fainelli <f.fainelli@...il.com>, linux-mips@...r.kernel.org
Cc:     Serge Semin <fancer.lancer@...il.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] MIPS: vdso: Utilize __pa() for gic_pfn


On 8/7/22 06:27, 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>

Fixes the issue of warnings on every process start with CONFIG_DEBUG_VIRTUAL
enabled for me. Thanks. So if you want:

Acked-by: Greg Ungerer <gerg@...nel.org>
Tested-by: Greg Ungerer <gerg@...nel.org>

Regards
Greg



> ---
>   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));