From: Christoph Hellwig <hch@lst.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>, Dexuan Cui <decui@microsoft.com>,
vkuznets <vkuznets@redhat.com>,
Stephen Hemminger <stephen@networkplumber.org>,
Andy Lutomirski <luto@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Michael Kelley <mikelley@microsoft.com>,
Ju-Hyoung Lee <juhlee@microsoft.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
KY Srinivasan <kys@microsoft.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: hv_hypercall_pg page permissios
Date: Tue, 16 Jun 2020 16:39:40 +0200 [thread overview]
Message-ID: <20200616143940.GA15676@lst.de> (raw)
In-Reply-To: <20200616112415.GT2531@hirez.programming.kicks-ass.net>
On Tue, Jun 16, 2020 at 01:24:15PM +0200, Peter Zijlstra wrote:
> > +void *module_alloc_prot(unsigned long size, pgprot_t prot)
> > {
> > + unsigned int flags = (pgprot_val(prot) & _PAGE_NX) ?
> > + 0 : VM_FLUSH_RESET_PERMS;
> > void *p;
> >
> > if (PAGE_ALIGN(size) > MODULES_LEN)
> > @@ -75,7 +77,7 @@ void *module_alloc(unsigned long size)
> > p = __vmalloc_node_range(size, MODULE_ALIGN,
> > MODULES_VADDR + get_module_load_offset(),
> > MODULES_END, GFP_KERNEL,
> > - PAGE_KERNEL, 0, NUMA_NO_NODE,
> > + prot, flags, NUMA_NO_NODE,
> > __builtin_return_address(0));
> > if (p && (kasan_module_alloc(p, size) < 0)) {
> > vfree(p);
>
> Hurmm.. Yes it would. It just doesn't feel right though. Can't we
> unconditionally set the flag? At worst it makes free a little bit more
> expensive.
>
> The thing is, I don't think _NX is the only prot that needs restoring.
> Any prot other than the default (RW IIRC) needs restoring.
If that actually is the case I think we should just check for
a non-default permission in __vmalloc_node_range itself and handle it
there, which seems like a nice solution.
next prev parent reply other threads:[~2020-06-16 14:39 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 6:55 hv_hypercall_pg page permissios Christoph Hellwig
2020-04-07 7:28 ` Vitaly Kuznetsov
2020-04-07 7:38 ` Christoph Hellwig
2020-04-07 21:01 ` Andy Lutomirski
2020-06-12 7:48 ` Dexuan Cui
2020-06-15 8:35 ` Vitaly Kuznetsov
2020-06-15 17:41 ` Dexuan Cui
2020-06-15 19:49 ` Dexuan Cui
2020-06-16 7:23 ` Christoph Hellwig
2020-06-16 10:18 ` Peter Zijlstra
2020-06-16 10:23 ` Christoph Hellwig
2020-06-16 10:24 ` Christoph Hellwig
2020-06-16 10:31 ` Peter Zijlstra
2020-06-16 10:33 ` Christoph Hellwig
2020-06-16 10:40 ` Peter Zijlstra
2020-06-16 10:42 ` Christoph Hellwig
2020-06-16 10:52 ` Christoph Hellwig
2020-06-16 11:24 ` Peter Zijlstra
2020-06-16 14:39 ` Christoph Hellwig [this message]
2020-06-16 9:29 ` Vitaly Kuznetsov
2020-06-16 9:33 ` Christoph Hellwig
2020-06-16 9:55 ` Christoph Hellwig
2020-06-16 10:08 ` Christoph Hellwig
2020-06-16 10:50 ` Vitaly Kuznetsov
2020-06-16 10:20 ` Peter Zijlstra
2020-04-07 18:10 ` Dexuan Cui
2020-04-07 20:42 ` Wei Liu
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