linux-kernel - Re: [PATCH v3 1/9] KVM: arm64: Enable UBSan instrumentation in nVHE hyp code

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Date:   Mon, 18 Jan 2021 09:53:50 +0000
From:   David Brazdil <dbrazdil@...gle.com>
To:     Elena Petrova <lenaptr@...gle.com>
Cc:     kvmarm@...ts.cs.columbia.edu,
        George-Aurelian Popescu <georgepope@...gle.com>,
        Marc Zyngier <maz@...nel.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        George Popescu <george.apopescu97@...il.com>
Subject: Re: [PATCH v3 1/9] KVM: arm64: Enable UBSan instrumentation in nVHE
 hyp code

On Fri, Jan 15, 2021 at 05:18:22PM +0000, Elena Petrova wrote:
> From: George-Aurelian Popescu <georgepope@...gle.com>
> 
> Implement UBSan handlers inside nVHe hyp code, as empty functions for the
> moment, so the undefined behaviours, that are triggered there, will be
> linked to them, not to the ones defined in kernel-proper lib/ubsan.c.
> 
> In this way, enabling UBSAN_MISC won't cause a link error.

The commit message needs to be updated - UBSAN_MISC does not exist any longer.
Also "nVHe" is a typo.

Other than that:
Acked-by: David Brazdil <dbrazdil@...gle.com>

> 
> Signed-off-by: Elena Petrova <lenaptr@...gle.com>
> ---
>  arch/arm64/kvm/hyp/nvhe/Makefile |  3 ++-
>  arch/arm64/kvm/hyp/nvhe/ubsan.c  | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 32 insertions(+), 1 deletion(-)
>  create mode 100644 arch/arm64/kvm/hyp/nvhe/ubsan.c
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index 1f1e351c5fe2..2a683e7c6c5b 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -10,6 +10,8 @@ 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-$(CONFIG_UBSAN) += ubsan.o
> +CFLAGS_ubsan.nvhe.o += -I $(srctree)/lib/
>  
>  ##
>  ## Build rules for compiling nVHE hyp code
> @@ -61,7 +63,6 @@ KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS), $(KBUILD_CFLAG
>  # cause crashes. Just disable it.
>  GCOV_PROFILE	:= n
>  KASAN_SANITIZE	:= n
> -UBSAN_SANITIZE	:= n
>  KCOV_INSTRUMENT	:= n
>  
>  # Skip objtool checking for this directory because nVHE code is compiled with
> diff --git a/arch/arm64/kvm/hyp/nvhe/ubsan.c b/arch/arm64/kvm/hyp/nvhe/ubsan.c
> new file mode 100644
> index 000000000000..a5db6b61ceb2
> --- /dev/null
> +++ b/arch/arm64/kvm/hyp/nvhe/ubsan.c
> @@ -0,0 +1,30 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2020 Google LLC
> + * Author: George Popescu <georgepope@...gle.com>
> + */
> +#include <linux/ctype.h>
> +#include <linux/types.h>
> +#include <ubsan.h>
> +
> +void __ubsan_handle_add_overflow(void *_data, void *lhs, void *rhs) {}
> +
> +void __ubsan_handle_sub_overflow(void *_data, void *lhs, void *rhs) {}
> +
> +void __ubsan_handle_mul_overflow(void *_data, void *lhs, void *rhs) {}
> +
> +void __ubsan_handle_negate_overflow(void *_data, void *old_val) {}
> +
> +void __ubsan_handle_divrem_overflow(void *_data, void *lhs, void *rhs) {}
> +
> +void __ubsan_handle_type_mismatch(struct type_mismatch_data *data, void *ptr) {}
> +
> +void __ubsan_handle_type_mismatch_v1(void *_data, void *ptr) {}
> +
> +void __ubsan_handle_out_of_bounds(void *_data, void *index) {}
> +
> +void __ubsan_handle_shift_out_of_bounds(void *_data, void *lhs, void *rhs) {}
> +
> +void __ubsan_handle_builtin_unreachable(void *_data) {}
> +
> +void __ubsan_handle_load_invalid_value(void *_data, void *val) {}
> -- 
> 2.30.0.296.g2bfb1c46d8-goog
> 
> _______________________________________________
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> kvmarm@...ts.cs.columbia.edu
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