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From: Dave Hansen <dave.hansen@intel.com>
To: Nadav Amit <nadav.amit@gmail.com>
Cc: Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Xu <peterx@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Will Deacon <will@kernel.org>, Yu Zhao <yuzhao@google.com>,
	Nick Piggin <npiggin@gmail.com>,
	x86@kernel.org
Subject: Re: [PATCH v2 3/5] x86/mm: check exec permissions on fault
Date: Mon, 25 Oct 2021 10:45:11 -0700	[thread overview]
Message-ID: <37d0b84c-f6ca-15cb-8d78-b6b5a9496da7@intel.com> (raw)
In-Reply-To: <00C2DC4B-A77D-4B32-B7F7-2291830BC2D2@gmail.com>

On 10/25/21 9:19 AM, Nadav Amit wrote:
> That was my first version, but I was concerned that perhaps there is
> some strange scenario in which both X86_PF_WRITE and X86_PF_INSN can
> be set. That is the reason that Peter asked you whether this is
> something that might happen.
> 
> If you confirm they cannot be both set, I would the version you just
> mentioned.

I'm pretty sure they can't be set together on any sane hardware.  A
bonkers hypervisor or CPU could do it of course, but they'd be crazy.

BTW, feel free to add a WARN_ON_ONCE() if WRITE and INSN are both set.
That would be a nice place to talk about the assumption.


  reply	other threads:[~2021-10-25 17:45 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21 12:21 [PATCH v2 0/5] mm/mprotect: avoid unnecessary TLB flushes Nadav Amit
2021-10-21 12:21 ` [PATCH v2 1/5] x86: Detection of Knights Landing A/D leak Nadav Amit
2021-10-26 15:54   ` Dave Hansen
2021-10-26 15:57     ` Nadav Amit
2021-10-21 12:21 ` [PATCH v2 2/5] mm: avoid unnecessary flush on change_huge_pmd() Nadav Amit
2021-10-25 10:52   ` Peter Zijlstra
2021-10-25 16:29     ` Nadav Amit
2021-10-26 16:06   ` Dave Hansen
2021-10-26 16:47     ` Nadav Amit
2021-10-26 16:53       ` Nadav Amit
2021-10-26 17:44       ` Nadav Amit
2021-10-26 18:44         ` Dave Hansen
2021-10-26 19:06           ` Nadav Amit
2021-10-26 19:40             ` Dave Hansen
2021-10-26 20:07               ` Nadav Amit
2021-10-26 20:47                 ` Dave Hansen
2021-10-21 12:21 ` [PATCH v2 3/5] x86/mm: check exec permissions on fault Nadav Amit
2021-10-25 10:59   ` Peter Zijlstra
2021-10-25 11:13     ` Andrew Cooper
2021-10-25 14:23     ` Dave Hansen
2021-10-25 14:20   ` Dave Hansen
2021-10-25 16:19     ` Nadav Amit
2021-10-25 17:45       ` Dave Hansen [this message]
2021-10-25 17:51         ` Nadav Amit
2021-10-25 18:00           ` Dave Hansen
2021-10-21 12:21 ` [PATCH v2 4/5] mm/mprotect: use mmu_gather Nadav Amit
2021-10-21 12:21 ` [PATCH v2 5/5] mm/mprotect: do not flush on permission promotion Nadav Amit
2021-10-25 11:12   ` Peter Zijlstra
2021-10-25 16:27     ` Nadav Amit
2021-10-22  3:04 ` [PATCH v2 0/5] mm/mprotect: avoid unnecessary TLB flushes Andrew Morton
2021-10-22 21:58   ` Nadav Amit
2021-10-26 16:09     ` Dave Hansen
2021-10-25 10:50   ` Peter Zijlstra
2021-10-25 16:42     ` Nadav Amit

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