From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C994EC3DA64 for ; Thu, 1 Aug 2024 10:56:10 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WZQqs2v5Sz3dLn for ; Thu, 1 Aug 2024 20:56:09 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=joey.gouly@arm.com; receiver=lists.ozlabs.org) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4WZQqR0X57z30YZ for ; Thu, 1 Aug 2024 20:55:43 +1000 (AEST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 39A931007; Thu, 1 Aug 2024 03:55:37 -0700 (PDT) Received: from e124191.cambridge.arm.com (e124191.cambridge.arm.com [10.1.197.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0C9023F5A1; Thu, 1 Aug 2024 03:55:07 -0700 (PDT) Date: Thu, 1 Aug 2024 11:55:02 +0100 From: Joey Gouly To: Dave Martin Subject: Re: [PATCH v4 13/29] arm64: convert protection key into vm_flags and pgprot values Message-ID: <20240801105502.GA841837@e124191.cambridge.arm.com> References: <20240503130147.1154804-1-joey.gouly@arm.com> <20240503130147.1154804-14-joey.gouly@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: szabolcs.nagy@arm.com, catalin.marinas@arm.com, dave.hansen@linux.intel.com, linux-mm@kvack.org, hpa@zytor.com, shuah@kernel.org, maz@kernel.org, x86@kernel.org, christophe.leroy@csgroup.eu, aneesh.kumar@kernel.org, mingo@redhat.com, naveen.n.rao@linux.ibm.com, will@kernel.org, npiggin@gmail.com, broonie@kernel.org, bp@alien8.de, kvmarm@lists.linux.dev, tglx@linutronix.de, linux-arm-kernel@lists.infradead.org, oliver.upton@linux.dev, aneesh.kumar@linux.ibm.com, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Jul 25, 2024 at 04:49:50PM +0100, Dave Martin wrote: > On Fri, May 03, 2024 at 02:01:31PM +0100, Joey Gouly wrote: > > Modify arch_calc_vm_prot_bits() and vm_get_page_prot() such that the pkey > > value is set in the vm_flags and then into the pgprot value. > > > > Signed-off-by: Joey Gouly > > Cc: Catalin Marinas > > Cc: Will Deacon > > --- > > arch/arm64/include/asm/mman.h | 8 +++++++- > > arch/arm64/mm/mmap.c | 9 +++++++++ > > 2 files changed, 16 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h > > index 5966ee4a6154..ecb2d18dc4d7 100644 > > --- a/arch/arm64/include/asm/mman.h > > +++ b/arch/arm64/include/asm/mman.h > > @@ -7,7 +7,7 @@ > > #include > > > > static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, > > - unsigned long pkey __always_unused) > > + unsigned long pkey) > > { > > unsigned long ret = 0; > > > > @@ -17,6 +17,12 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot, > > if (system_supports_mte() && (prot & PROT_MTE)) > > ret |= VM_MTE; > > > > +#if defined(CONFIG_ARCH_HAS_PKEYS) > > + ret |= pkey & 0x1 ? VM_PKEY_BIT0 : 0; > > + ret |= pkey & 0x2 ? VM_PKEY_BIT1 : 0; > > + ret |= pkey & 0x4 ? VM_PKEY_BIT2 : 0; > > Out of interest, is this as bad as it looks or does the compiler turn > it into a shift and mask? Yeah, (gcc 13.2) produces good code here (this is do_mprotect_pkey after removing a lot of branching): and w0, w0, #0x7 orr x1, x1, x0, lsl #32 > > > > +#endif > > + > > return ret; > > } > > #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey) > > diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c > > index 642bdf908b22..86eda6bc7893 100644 > > --- a/arch/arm64/mm/mmap.c > > +++ b/arch/arm64/mm/mmap.c > > @@ -102,6 +102,15 @@ pgprot_t vm_get_page_prot(unsigned long vm_flags) > > if (vm_flags & VM_MTE) > > prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED); > > > > +#ifdef CONFIG_ARCH_HAS_PKEYS > > + if (vm_flags & VM_PKEY_BIT0) > > + prot |= PTE_PO_IDX_0; > > + if (vm_flags & VM_PKEY_BIT1) > > + prot |= PTE_PO_IDX_1; > > + if (vm_flags & VM_PKEY_BIT2) > > + prot |= PTE_PO_IDX_2; > > +#endif > > + > > Ditto. At least we only have three bits to cope with either way. > > I'm guessing that these functions are not super-hot path. > > [...] > > Cheers > ---Dave