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Subject: Re: [PATCH] pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change
 signal semantics
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From: Florian Weimer <fweimer@redhat.com>
Message-ID: <9c7b1c17-5c0e-11aa-0803-a0f503087b37@redhat.com>
Date: Thu, 17 May 2018 12:11:15 +0200
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To: Ram Pai <linuxram@us.ibm.com>
Cc: Andy Lutomirski <luto@kernel.org>, Dave Hansen <dave.hansen@intel.com>, Linux-MM <linux-mm@kvack.org>, Linux API <linux-api@vger.kernel.org>, linux-x86_64@vger.kernel.org, linux-arch <linux-arch@vger.kernel.org>, X86 ML <x86@kernel.org>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>

On 05/16/2018 10:35 PM, Ram Pai wrote:
> So let me see if I understand the overall idea.
> 
> Application can allocate new keys through a new syscall
> sys_pkey_alloc_1(flags, init_val, sig_init_val)
> 
> 'sig_init_val' is the permission-state of the key in signal context.

I would keep the existing system call and just add a flag, say 
PKEY_ALLOC_SETSIGNAL.  If the current thread needs different access 
rights, it can set those rights just after pkey_alloc returns.  There is 
no race that matters here, I think.

Thanks,
Florian