From: Christoph Hellwig <hch@lst.de>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>, Dexuan Cui <decui@microsoft.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
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: Tue, 23 Jun 2020 11:05:05 +0200 [thread overview]
Message-ID: <20200623090505.GA7518@lst.de> (raw)
In-Reply-To: <20200620191616.bae356186ba3329ade67bbf7@linux-foundation.org>
On Sat, Jun 20, 2020 at 07:16:16PM -0700, Andrew Morton wrote:
> On Thu, 18 Jun 2020 08:43:06 +0200 Christoph Hellwig <hch@lst.de> wrote:
>
> > Use PAGE_KERNEL_ROX directly instead of allocating RWX and setting the
> > page read-only just after the allocation.
> >
> > --- 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__);
> > }
> >
> > /* arm kprobe: install breakpoint in text */
>
> But why. I think this is just a cleanup, doesn't address any runtime issue?
It doesn't "fix" an issue - it just simplifies and speeds up the code.
next prev parent reply other threads:[~2020-06-23 9:05 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
2020-06-18 9:27 ` Peter Zijlstra
2020-06-21 2:16 ` Andrew Morton
2020-06-23 9:05 ` Christoph Hellwig [this message]
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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