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

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Date:   Fri, 15 Jan 2021 17:18:22 +0000
From:   Elena Petrova <lenaptr@...gle.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Elena Petrova <lenaptr@...gle.com>,
        linux-arm-kernel@...ts.infradead.org,
        open list <linux-kernel@...r.kernel.org>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        George Popescu <george.apopescu97@...il.com>,
        George-Aurelian Popescu <georgepope@...gle.com>
Subject: [PATCH v3 1/9] KVM: arm64: Enable UBSan instrumentation in nVHE hyp code

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.

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