ubsan: Remove CONFIG_UBSAN_SANITIZE_ALL

For simplicity in splitting out UBSan options into separate rules,
remove CONFIG_UBSAN_SANITIZE_ALL, effectively defaulting to "y", which
is how it is generally used anyway. (There are no ":= y" cases beyond
where a specific file is enabled when a top-level ":= n" is in effect.)

Cc: Andrey Konovalov <[e-mail]>
Cc: Marco Elver <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Kees Cook <[e-mail]>

Documentation/dev-tools/ubsan.rst

···
 Usage
 -----
 
-To enable UBSAN configure kernel with::
+To enable UBSAN, configure the kernel with::
 
-	CONFIG_UBSAN=y
+  CONFIG_UBSAN=y
 
-and to check the entire kernel::
-
-        CONFIG_UBSAN_SANITIZE_ALL=y
-
-To enable instrumentation for specific files or directories, add a line
-similar to the following to the respective kernel Makefile:
-
-- For a single file (e.g. main.o)::
-
-    UBSAN_SANITIZE_main.o := y
-
-- For all files in one directory::
-
-    UBSAN_SANITIZE := y
-
-To exclude files from being instrumented even if
-``CONFIG_UBSAN_SANITIZE_ALL=y``, use::
+To exclude files from being instrumented use::
 
   UBSAN_SANITIZE_main.o := n
 
-and::
+and to exclude all targets in one directory use::
 
   UBSAN_SANITIZE := n
+
+When disabled for all targets, specific files can be enabled using::
+
+  UBSAN_SANITIZE_main.o := y
 
 Detection of unaligned accesses controlled through the separate option -
 CONFIG_UBSAN_ALIGNMENT. It's off by default on architectures that support

arch/arm/Kconfig

···
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG if CPU_V7 || CPU_V7M || CPU_V6K
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_KEEP_MEMBLOCK
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_MIGHT_HAVE_PC_PARPORT
 	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7

arch/arm64/Kconfig

···
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANTS_THP_SWAP if ARM64_4K_PAGES
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARM_AMBA
 	select ARM_ARCH_TIMER
 	select ARM_GIC

arch/mips/Kconfig

···
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_KEEP_MEMBLOCK
 	select ARCH_USE_BUILTIN_BSWAP

arch/parisc/Kconfig

···
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_NO_SG_CHAIN
 	select ARCH_SUPPORTS_HUGETLBFS if PA20

arch/powerpc/Kconfig

···
 	select ARCH_HAS_SYSCALL_WRAPPER		if !SPU_BASE && !COMPAT
 	select ARCH_HAS_TICK_BROADCAST		if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAS_UACCESS_FLUSHCACHE
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_KEEP_MEMBLOCK
 	select ARCH_MHP_MEMMAP_ON_MEMORY_ENABLE	if PPC_RADIX_MMU

arch/riscv/Kconfig

···
 	select ARCH_HAS_STRICT_MODULE_RWX if MMU && !XIP_KERNEL
 	select ARCH_HAS_SYSCALL_WRAPPER
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAS_VDSO_DATA
 	select ARCH_KEEP_MEMBLOCK if ACPI
 	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX

arch/s390/Kconfig

···
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_SYSCALL_WRAPPER
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAS_VDSO_DATA
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_INLINE_READ_LOCK

arch/x86/Kconfig

···
 	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE
 	select ARCH_HAS_SYSCALL_WRAPPER
-	select ARCH_HAS_UBSAN_SANITIZE_ALL
+	select ARCH_HAS_UBSAN
 	select ARCH_HAS_DEBUG_WX
 	select ARCH_HAS_ZONE_DMA_SET if EXPERT
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG

lib/Kconfig.ubsan

···
 # SPDX-License-Identifier: GPL-2.0-only
-config ARCH_HAS_UBSAN_SANITIZE_ALL
+config ARCH_HAS_UBSAN
 	bool
 
 menuconfig UBSAN
···
 	  This option enables the check of unaligned memory accesses.
 	  Enabling this option on architectures that support unaligned
 	  accesses may produce a lot of false positives.
-
-config UBSAN_SANITIZE_ALL
-	bool "Enable instrumentation for the entire kernel"
-	depends on ARCH_HAS_UBSAN_SANITIZE_ALL
-	default y
-	help
-	  This option activates instrumentation for the entire kernel.
-	  If you don't enable this option, you have to explicitly specify
-	  UBSAN_SANITIZE := y for the files/directories you want to check for UB.
-	  Enabling this option will get kernel image size increased
-	  significantly.
 
 config TEST_UBSAN
 	tristate "Module for testing for undefined behavior detection"

scripts/Makefile.lib

···
 
 ifeq ($(CONFIG_UBSAN),y)
 _c_flags += $(if $(patsubst n%,, \
-		$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)$(CONFIG_UBSAN_SANITIZE_ALL)), \
+		$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)y), \
 		$(CFLAGS_UBSAN))
 endif