Re: [RFC PATCH 02/27] KVM: arm64: Link position-independent string routines into .hyp.text

From: David Brazdil <dbrazdil@google.com>
To: Quentin Perret <qperret@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
	James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	"moderated list:ARM64 PORT (AARCH64 ARCHITECTURE)" 
	<linux-arm-kernel@lists.infradead.org>,
	open list <linux-kernel@vger.kernel.org>,
	"open list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" 
	<kvmarm@lists.cs.columbia.edu>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
	<devicetree@vger.kernel.org>,
	kernel-team@android.com, android-kvm@google.com
Subject: Re: [RFC PATCH 02/27] KVM: arm64: Link position-independent string routines into .hyp.text
Date: Mon, 23 Nov 2020 12:34:25 +0000	[thread overview]
Message-ID: <20201123123425.uzfuk3pmwgzuijwn@google.com> (raw)
In-Reply-To: <20201117181607.1761516-3-qperret@google.com>

On Tue, Nov 17, 2020 at 06:15:42PM +0000, 'Quentin Perret' via kernel-team wrote:
> From: Will Deacon <will@kernel.org>
> 
> Pull clear_page(), copy_page(), memcpy() and memset() into the nVHE hyp
> code and ensure that we always execute the '__pi_' entry point on the
> offchance that it changes in future.
> 
> [ qperret: Commit title nits ]
> 
> Signed-off-by: Will Deacon <will@kernel.org>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
>  arch/arm64/kernel/image-vars.h   | 11 +++++++++++
>  arch/arm64/kvm/hyp/nvhe/Makefile |  4 ++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 8539f34d7538..dd8ccc9efb6a 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -105,6 +105,17 @@ KVM_NVHE_ALIAS(__stop___kvm_ex_table);
>  /* Array containing bases of nVHE per-CPU memory regions. */
>  KVM_NVHE_ALIAS(kvm_arm_hyp_percpu_base);
>  
> +/* Position-independent library routines */
> +__kvm_nvhe_clear_page			= __kvm_nvhe___pi_clear_page;
> +__kvm_nvhe_copy_page			= __kvm_nvhe___pi_copy_page;
> +__kvm_nvhe_memcpy			= __kvm_nvhe___pi_memcpy;
> +__kvm_nvhe_memset			= __kvm_nvhe___pi_memset;
> +
> +#ifdef CONFIG_KASAN
> +__kvm_nvhe___memcpy			= __kvm_nvhe___pi_memcpy;
> +__kvm_nvhe___memset			= __kvm_nvhe___pi_memset;
> +#endif
> +
>  #endif /* CONFIG_KVM */

Nit: Would be good to use the kvm_nvhe_sym() helper for the namespacing.
And feel free to define something like KVM_NVHE_ALIAS for PI in hyp-image.h.

>  
>  #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index 1f1e351c5fe2..590fdefb42dd 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -6,10 +6,14 @@
>  asflags-y := -D__KVM_NVHE_HYPERVISOR__
>  ccflags-y := -D__KVM_NVHE_HYPERVISOR__
>  
> +lib-objs := clear_page.o copy_page.o memcpy.o memset.o
> +lib-objs := $(addprefix ../../../lib/, $(lib-objs))
> +
>  obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o \
>  	 hyp-main.o hyp-smp.o psci-relay.o
>  obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
>  	 ../fpsimd.o ../hyp-entry.o ../exception.o
> +obj-y += $(lib-objs)
>  
>  ##
>  ## Build rules for compiling nVHE hyp code
> -- 
> 2.29.2.299.gdc1121823c-goog
> 
> -- 
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