From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BFD243FB31; Sun, 21 Sep 2025 07:36:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758440211; cv=none; b=W52wGFJmE0mpoHGO/FAs09bHtvzZTHJ0tQvhFNt3RRkn0F5YmBteyNoDh/jBTwVGPjO5Fa3jZl1X3qumPj6K6KNpcts5nJS3PEK5ccpK+f5HxNneVohVcvEDR8uDVlJkxGaf+17hcjRc1DPiyK5pVu1o1NXgWDWf3N9nKJbSnRY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758440211; c=relaxed/simple; bh=u+7GWK94K2d12xoNceoyNQMPQ+Avsc5hXDrIp3bhOiw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Vul3RdD83XcoJWZn6df4Q/NGyEicGLH+J85HWd++qRQkysDlOV0dPXub7HmJgZv6+D3i5mCJ0ulj2fdpQBRkTc/frTUK0thShcc7OYWSzQefVOGilq1fgrLp9WZUvVN5FrJGObVz+boflvNLO1dB81uhr63Vazs1PgVRWRPVOoQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ARVmY+Vz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ARVmY+Vz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DE8C8C4CEE7; Sun, 21 Sep 2025 07:36:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758440211; bh=u+7GWK94K2d12xoNceoyNQMPQ+Avsc5hXDrIp3bhOiw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ARVmY+VzcXR/pwJD4cJSRgX+IajyrlajMfIWP/OlGMJvNOua8lbiv+guGXgycID6i 4ONFjQRLNiTR6Jr3gN/jljj8TWjlKiMfcsW7UPrZ0Xq7k7AhRStXbFpgfr2wJT4vI8 /I6zUmRm7+RhZM9XtLRt5Esv6URS2lD51qwKNifB4yUl3OwFQZUZiYUwjHYAqtevdR JnMoUojwQxcrSZjkuXMidH8izfveUAtlaFtMrMW53mTwPKPD/lasRlrt/TvPE/9UWk /r01Y3y6nxVidYXq/ZsQ+m3klo8QUcyujlIiSheFX2GDlAjZ3GLwEsv01HPfVbyTRO j2wz/sYZAtZ1w== Date: Sun, 21 Sep 2025 10:36:44 +0300 From: Mike Rapoport To: Yang Shi Cc: Will Deacon , catalin.marinas@arm.com, ryan.roberts@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [v2 PATCH] arm64: kprobes: call set_memory_rox() for kprobe page Message-ID: References: <20250918162349.4031286-1-yang@os.amperecomputing.com> <8df9d007-f363-4488-96e9-fbf017d9c8e2@os.amperecomputing.com> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8df9d007-f363-4488-96e9-fbf017d9c8e2@os.amperecomputing.com> On Thu, Sep 18, 2025 at 10:33:26AM -0700, Yang Shi wrote: > > > On 9/18/25 10:26 AM, Will Deacon wrote: > > On Thu, Sep 18, 2025 at 09:23:49AM -0700, Yang Shi wrote: > > > The kprobe page is allocated by execmem allocator with ROX permission. > > > It needs to call set_memory_rox() to set proper permission for the > > > direct map too. It was missed. > > > > > > Fixes: 10d5e97c1bf8 ("arm64: use PAGE_KERNEL_ROX directly in alloc_insn_page") > > > Cc: > > > Signed-off-by: Yang Shi > > > Reviewed-by: Catalin Marinas > > > --- > > > v2: Separated the patch from BBML2 series since it is an orthogonal bug > > > fix per Ryan. > > > Fixed the variable name nit per Catalin. > > > Collected R-bs from Catalin. > > > > > > arch/arm64/kernel/probes/kprobes.c | 12 ++++++++++++ > > > 1 file changed, 12 insertions(+) > > > > > > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c > > > index 0c5d408afd95..8ab6104a4883 100644 > > > --- a/arch/arm64/kernel/probes/kprobes.c > > > +++ b/arch/arm64/kernel/probes/kprobes.c > > > @@ -10,6 +10,7 @@ > > > #define pr_fmt(fmt) "kprobes: " fmt > > > +#include > > > #include > > > #include > > > #include > > > @@ -41,6 +42,17 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); > > > static void __kprobes > > > post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *); > > > +void *alloc_insn_page(void) > > > +{ > > > + void *addr; > > > + > > > + addr = execmem_alloc(EXECMEM_KPROBES, PAGE_SIZE); > > > + if (!addr) > > > + return NULL; > > > + set_memory_rox((unsigned long)addr, 1); > > > + return addr; > > > +} > > Why isn't execmem taking care of this? It looks to me like the > > execmem_cache_alloc() path calls set_memory_rox() but the > > execmem_vmalloc() path doesn't? execmem_alloc() -> execmem_vmalloc() consolidated __vmalloc_node_range() for executable allocations. Those also didn't update the linear map alias. It could be added to execmem_vmalloc(), but as of now we don't have a way for generic code to tell which set_memory method to call based on pgprot, so making execmem_vmalloc() to deal with direct map alias is quite involved. It would be easier to just remove the direct map alias. It works on x86 so I don't see what can possibly go wrong :) > execmem_cache_alloc() is just called if execmem ROX cache is enabled, but it > currently just supported by x86. Included Mike to this thread who is the > author of execmem ROX cache. > > > > > It feels a bit bizarre to me that we have to provide our own wrapper > > (which is identical to what s390 does). Also, how does alloc_insn_page() > > handle the direct map alias on x86? s390 had its version of alloc_insn_page() long before execmem so there I just replaced module_alloc() with exemem_alloc(). arm64 version of alloc_insn_page() didn't update the direct map before execmem, so I overlooked this issue when I was converting arm64 to execmem. > x86 handles it via execmem ROX cache. > > Thanks, > Yang > > > > > Will > -- Sincerely yours, Mike.