linux-kernel - Re: hv_hypercall

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Message-ID: <20200616104230.GA31314@lst.de>
Date:   Tue, 16 Jun 2020 12:42:30 +0200
From:   Christoph Hellwig <hch@....de>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Christoph Hellwig <hch@....de>, Dexuan Cui <decui@...rosoft.com>,
        vkuznets <vkuznets@...hat.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Andy Lutomirski <luto@...nel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Michael Kelley <mikelley@...rosoft.com>,
        Ju-Hyoung Lee <juhlee@...rosoft.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        KY Srinivasan <kys@...rosoft.com>,
        Tom Lendacky <thomas.lendacky@....com>
Subject: Re: hv_hypercall_pg page permissios

On Tue, Jun 16, 2020 at 12:40:32PM +0200, Peter Zijlstra wrote:
> On Tue, Jun 16, 2020 at 12:33:13PM +0200, Christoph Hellwig wrote:
> > sorry, s/ftrace/kprobes/.  See my updated branch here:
> > 
> > http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/module_alloc-cleanup
> 
> Ah the insn slot page, yes. Didn't you just loose VM_FLUSH_RESET_PERMS
> there?

Yes, we did.  vmalloc_exec had it, but given that module_alloc didn't
allocate executable on x86 it didn't.  I guess we should make sure it
is set by the low-level vmalloc code if exec permissions are set to
sort this mess out.