[PATCH 01/14] KVM: arm64: Enable UBSan instrumentation in nVHE hyp code

[George-Aurelian Popescu]

From: George Popescu <georgepope at google.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: George Popescu <georgepope at google.com>
---
 arch/arm64/kvm/hyp/nvhe/Makefile |  4 +++-
 arch/arm64/kvm/hyp/nvhe/ubsan.c  | 30 ++++++++++++++++++++++++++++++
 2 files changed, 33 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 aef76487edc2..cc082e516353 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -10,6 +10,9 @@ obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o
 obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../fpsimd.o ../hyp-entry.o
 
+CFLAGS_ubsan.hyp.tmp.o += -I $(srctree)/lib/
+obj-$(CONFIG_UBSAN) += ubsan.o
+
 obj-y := $(patsubst %.o,%.hyp.o,$(obj-y))
 extra-y := $(patsubst %.hyp.o,%.hyp.tmp.o,$(obj-y))
 
@@ -54,7 +57,6 @@ 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 at google.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) {}
-- 
2.28.0.618.gf4bc123cb7-goog