[PATCH v2 6/6] ubsan: Get x86_64 booting with unsigned wrap-around sanitizer

@@ -30,6 +30,7 @@ KASAN_SANITIZE_sev.o					:= n
 
 # With some compiler versions the generated code results in boot hangs, caused
 # by several compilation units. To be safe, disable all instrumentation.
+UBSAN_WRAP_UNSIGNED := n
 KCSAN_SANITIZE := n
 KMSAN_SANITIZE_head$(BITS).o				:= n
 KMSAN_SANITIZE_nmi.o					:= n

@@ -6,6 +6,7 @@
 # Leads to non-deterministic coverage that is not a function of syscall inputs.
 # In particular, smp_apic_timer_interrupt() is called in random places.
 KCOV_INSTRUMENT		:= n
+UBSAN_WRAP_UNSIGNED	:= n
 
 obj-$(CONFIG_X86_LOCAL_APIC)	+= apic.o apic_common.o apic_noop.o ipi.o vector.o init.o
 obj-y				+= hw_nmi.o

@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 # Kernel does not boot with instrumentation of tlb.c and mem_encrypt*.c
+UBSAN_WRAP_UNSIGNED := n
 KCOV_INSTRUMENT_tlb.o			:= n
 KCOV_INSTRUMENT_mem_encrypt.o		:= n
 KCOV_INSTRUMENT_mem_encrypt_amd.o	:= n

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+UBSAN_WRAP_UNSIGNED := n
 
 obj-y				:= set_memory.o memtype.o
 

@@ -2,6 +2,7 @@
 #
 # Cryptographic API
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-$(CONFIG_CRYPTO) += crypto.o
 crypto-y := api.o cipher.o compress.o

@@ -2,6 +2,7 @@
 #
 # Makefile for the Linux ACPI interpreter
 #
+UBSAN_WRAP_UNSIGNED := n
 
 ccflags-$(CONFIG_ACPI_DEBUG)	+= -DACPI_DEBUG_OUTPUT
 

@@ -2,6 +2,7 @@
 #
 # Makefile for the linux kernel.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-y     = fork.o exec_domain.o panic.o \
 	    cpu.o exit.o softirq.o resource.o \

@@ -2,6 +2,7 @@
 # Any varying coverage in these files is non-deterministic
 # and is generally not a function of system call inputs.
 KCOV_INSTRUMENT		:= n
+UBSAN_WRAP_UNSIGNED	:= n
 
 obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
 

@@ -2,6 +2,7 @@
 # Any varying coverage in these files is non-deterministic
 # and is generally not a function of system call inputs.
 KCOV_INSTRUMENT := n
+UBSAN_WRAP_UNSIGNED := n
 
 ifeq ($(CONFIG_KCSAN),y)
 KBUILD_CFLAGS += -g -fno-omit-frame-pointer

@@ -7,6 +7,7 @@ ccflags-y += $(call cc-disable-warning, unused-but-set-variable)
 # These files are disabled because they produce non-interesting flaky coverage
 # that is not a function of syscall inputs. E.g. involuntary context switches.
 KCOV_INSTRUMENT := n
+UBSAN_WRAP_UNSIGNED := n
 
 # Disable KCSAN to avoid excessive noise and performance degradation. To avoid
 # false positives ensure barriers implied by sched functions are instrumented.

@@ -132,8 +132,9 @@ config UBSAN_UNSIGNED_WRAP
 	depends on !COMPILE_TEST
 	help
 	  This option enables -fsanitize=unsigned-integer-overflow which checks
-	  for wrap-around of any arithmetic operations with unsigned integers. This
-	  currently causes x86 to fail to boot.
+	  for wrap-around of any arithmetic operations with unsigned integers.
+	  Given the history of C and the many common code patterns involving
+	  unsigned wrap-around, this is a very noisy option right now.
 
 config UBSAN_POINTER_WRAP
 	bool "Perform checking for pointer arithmetic wrap-around"

@@ -2,6 +2,7 @@
 #
 # Makefile for some libs needed in the kernel.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
 

@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+UBSAN_WRAP_UNSIGNED := n
 
 obj-$(CONFIG_CRYPTO_LIB_UTILS)			+= libcryptoutils.o
 libcryptoutils-y				:= memneq.o utils.o

@@ -2,6 +2,7 @@
 #
 # MPI multiprecision maths library (from gpg)
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-$(CONFIG_MPILIB) = mpi.o
 

@@ -6,6 +6,7 @@
 # This is the compression code, see zlib_inflate for the
 # decompression code.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate.o
 

@@ -8,6 +8,8 @@
 # in the COPYING file in the root directory of this source tree).
 # You may select, at your option, one of the above-listed licenses.
 # ################################################################
+UBSAN_WRAP_UNSIGNED := n
+
 obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o
 obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o
 obj-$(CONFIG_ZSTD_COMMON) += zstd_common.o

@@ -2,6 +2,7 @@
 #
 # Makefile for the linux memory manager.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 KASAN_SANITIZE_slab_common.o := n
 KASAN_SANITIZE_slub.o := n

@@ -2,6 +2,7 @@
 #
 # Makefile for the Linux networking core.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-y := sock.o request_sock.o skbuff.o datagram.o stream.o scm.o \
 	 gen_stats.o gen_estimator.o net_namespace.o secure_seq.o \

@@ -2,6 +2,7 @@
 #
 # Makefile for the Linux TCP/IP (INET) layer.
 #
+UBSAN_WRAP_UNSIGNED := n
 
 obj-y     := route.o inetpeer.o protocol.o \
 	     ip_input.o ip_fragment.o ip_forward.o ip_options.o \