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From: Paul Burton <paulburton@kernel.org>
To: Guoyun Sun <sunguoyun@loongson.cn>
Cc: Ralf Baechle <ralf@linux-mips.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Allison Randal <allison@lohutok.net>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH]  mips/vdso: Support mremap() for vDSO
Date: Tue, 14 Jan 2020 16:08:15 -0800	[thread overview]
Message-ID: <20200115000815.narpydp4unkkuboj@pburton-laptop> (raw)
In-Reply-To: <1578978808-18633-1-git-send-email-sunguoyun@loongson.cn>

Hi Guoyun,

On Tue, Jan 14, 2020 at 01:13:28PM +0800, Guoyun Sun wrote:
> diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c
> index bc35f84..eac3982 100644
> --- a/arch/mips/kernel/vdso.c
> +++ b/arch/mips/kernel/vdso.c
> @@ -38,6 +38,28 @@ static struct vm_special_mapping vdso_vvar_mapping = {
>  	.pages = no_pages,
>  };
>  
> +int vdso_mremap(const struct vm_special_mapping *sm,
> +		       struct vm_area_struct *new_vma)
> +{
> +	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
> +
> +#ifdef CONFIG_MIPS32_O32
> +	if (vdso_image_o32.size != new_size)
> +		return -EINVAL;
> +#endif
> +
> +#ifdef CONFIG_MIPS32_N32
> +	if (vdso_image_n32.size != new_size)
> +		return -EINVAL;
> +#endif
> +
> +	if (vdso_image.size != new_size)
> +		return -EINVAL;
> +
> +	current->mm->context.vdso = (void __user *)(new_vma->vm_start);
> +	return 0;
> +}
> +

Thanks for the patch; this bit doesn't seem right though. It requires
that all the VDSOs be the same size, which seems questionable. I think
we probably need separate mremap callbacks for each VDSO, so that we can
check the appropriate VDSO size.

Thanks,
    Paul

      reply	other threads:[~2020-01-15  0:08 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-14  5:13 [PATCH] mips/vdso: Support mremap() for vDSO Guoyun Sun
2020-01-15  0:08 ` Paul Burton [this message]

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