linux-kernel - Re: [PATCH 10/26] x86, pkeys: notify userspace about protection key faults

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Message-ID: <alpine.DEB.2.11.1509222157050.5606@nanos>
Date:	Tue, 22 Sep 2015 22:03:08 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Dave Hansen <dave@...1.net>
cc:	x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 10/26] x86, pkeys: notify userspace about protection key
 faults

On Wed, 16 Sep 2015, Dave Hansen wrote:
>  
> +static inline u16 vma_pkey(struct vm_area_struct *vma)
> +{
> +	u16 pkey = 0;
> +#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
> +	unsigned long f = vma->vm_flags;
> +	pkey |= (!!(f & VM_HIGH_ARCH_0)) << 0;
> +	pkey |= (!!(f & VM_HIGH_ARCH_1)) << 1;
> +	pkey |= (!!(f & VM_HIGH_ARCH_2)) << 2;
> +	pkey |= (!!(f & VM_HIGH_ARCH_3)) << 3;

Eew. What's wrong with:

     pkey = (vma->vm_flags & VM_PKEY_MASK) >> VM_PKEY_SHIFT;

???

> +static u16 fetch_pkey(unsigned long address, struct task_struct *tsk)

So here we get a u16 and assign it to si_pkey

> +	if (boot_cpu_has(X86_FEATURE_OSPKE) && si_code == SEGV_PKUERR)
> +		info.si_pkey = fetch_pkey(address, tsk);

which is int.

> +			int _pkey; /* FIXME: protection key value??

Inconsistent at least.

Thanks,

	tglx
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