From: Christoph Hellwig <hch@lst.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: David Hildenbrand <david@redhat.com>,
Christoph Hellwig <hch@lst.de>,
Andrew Morton <akpm@linux-foundation.org>,
Dexuan Cui <decui@microsoft.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
x86@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 2/3] arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page
Date: Thu, 18 Jun 2020 15:50:27 +0200 [thread overview]
Message-ID: <20200618135027.GA23534@lst.de> (raw)
In-Reply-To: <20200618103506.GH576905@hirez.programming.kicks-ass.net>
On Thu, Jun 18, 2020 at 12:35:06PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 18, 2020 at 10:55:58AM +0200, David Hildenbrand wrote:
> > On 18.06.20 08:43, Christoph Hellwig wrote:
> > > Use PAGE_KERNEL_ROX directly instead of allocating RWX and setting the
> > > page read-only just after the allocation.
> > >
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > ---
> > > arch/arm64/kernel/probes/kprobes.c | 12 +++---------
> > > 1 file changed, 3 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> > > index d1c95dcf1d7833..cbe49cd117cfec 100644
> > > --- a/arch/arm64/kernel/probes/kprobes.c
> > > +++ b/arch/arm64/kernel/probes/kprobes.c
> > > @@ -120,15 +120,9 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
> > >
> > > void *alloc_insn_page(void)
> > > {
> > > - void *page;
> > > -
> > > - page = vmalloc_exec(PAGE_SIZE);
> > > - if (page) {
> > > - set_memory_ro((unsigned long)page, 1);
> > > - set_vm_flush_reset_perms(page);
> > > - }
> > > -
> > > - return page;
> > > + return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
> > > + GFP_KERNEL, PAGE_KERNEL_ROX, VM_FLUSH_RESET_PERMS,
> > > + NUMA_NO_NODE, __func__);
> >
> > I do wonder if something like vmalloc_prot(size, prot) would make this
> > (and the other two users) easier to read.
> >
> > So instead of ripping out vmalloc_exec(), converting it into
> > vmalloc_prot() instead.
> >
> > Did you consider that?
>
> For x86 Christoph did module_alloc_prot(), which is in his more
> extensive set of patches addressing this. I suspect that would be the
> right thing for ARM64 as well.
Yes. The somewhat hacky way I added it cause problems for UML, so I
instead plan to do a series converting all architectures over to
module_alloc_prot, plus lots of other cleanups in the area that I
noticed.
I don't think vmalloc_prot is a good idea per se, as there only few
potential users, and I don't want too many vmalloc APIs.
next prev parent reply other threads:[~2020-06-18 13:50 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 6:43 fix a hyperv W^X violation and remove vmalloc_exec Christoph Hellwig
2020-06-18 6:43 ` [PATCH 1/3] x86/hyperv: allocate the hypercall page with only read and execute bits Christoph Hellwig
2020-06-18 11:47 ` Wei Liu
2020-06-18 6:43 ` [PATCH 2/3] arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page Christoph Hellwig
2020-06-18 8:55 ` David Hildenbrand
2020-06-18 10:35 ` Peter Zijlstra
2020-06-18 13:50 ` Christoph Hellwig [this message]
2020-06-18 9:27 ` Peter Zijlstra
2020-06-21 2:16 ` Andrew Morton
2020-06-23 9:05 ` Christoph Hellwig
2020-06-23 9:07 ` Will Deacon
2020-06-23 9:37 ` Peter Zijlstra
2020-06-23 9:57 ` Will Deacon
2020-06-27 7:34 ` Ard Biesheuvel
2020-06-27 7:56 ` Christoph Hellwig
2020-06-27 7:57 ` Ard Biesheuvel
2020-06-18 6:43 ` [PATCH 3/3] mm: remove vmalloc_exec Christoph Hellwig
2020-06-18 8:53 ` David Hildenbrand
2020-06-18 9:28 ` fix a hyperv W^X violation and " Peter Zijlstra
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