[RFC 02/32] Kconfig: introduce HAS_IOPORT option and select it as necessary

[Niklas Schnelle <schnelle@linux.ibm.com>]

We introduce a new HAS_IOPORT Kconfig option to gate support for
I/O port access. In a future patch HAS_IOPORT=n will disable compilation
of the I/O accessor functions inb()/outb() and friends on architectures
which can not meaningfully support legacy I/O spaces. On these platforms
inb()/outb() etc are currently just stubs in asm-generic/io.h which when
called will cause a NULL pointer access which some compilers actually
detect and warn about.

The dependencies on HAS_IOPORT in drivers as well as ifdefs for
HAS_IOPORT specific sections will be added in subsequent patches on
a per subsystem basis. Then a final patch will ifdef the I/O access
functions on HAS_IOPORT thus turning any use not gated by HAS_IOPORT
into a compile-time warning.

Link: https://lore.kernel.org/lkml/CAHk-=wg80je=K7madF4e7WrRNp37e3qh6y10Svhdc7O8SZ_-8g@mail.gmail.com/
Co-developed-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
---
 arch/alpha/Kconfig      | 1 +
 arch/arc/Kconfig        | 1 +
 arch/arm/Kconfig        | 1 +
 arch/arm64/Kconfig      | 1 +
 arch/ia64/Kconfig       | 1 +
 arch/m68k/Kconfig       | 1 +
 arch/microblaze/Kconfig | 1 +
 arch/mips/Kconfig       | 1 +
 arch/parisc/Kconfig     | 1 +
 arch/powerpc/Kconfig    | 1 +
 arch/riscv/Kconfig      | 1 +
 arch/sh/Kconfig         | 1 +
 arch/sparc/Kconfig      | 1 +
 arch/x86/Kconfig        | 1 +
 drivers/bus/Kconfig     | 2 +-
 lib/Kconfig             | 4 ++++
 lib/Kconfig.kgdb        | 1 +
 17 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 4e87783c90ad..472a0c5e4c2f 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -28,6 +28,7 @@ config ALPHA
 	select AUDIT_ARCH
 	select GENERIC_CPU_VULNERABILITIES
 	select GENERIC_SMP_IDLE_THREAD
+	select HAS_IOPORT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_MOD_ARCH_SPECIFIC
 	select MODULES_USE_ELF_RELA
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index b4ae6058902a..b3911ebbd237 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -27,6 +27,7 @@ config ARC
 	select GENERIC_PENDING_IRQ if SMP
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
+	select HAS_IOPORT
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARC_MMU_V4
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c2724d986fa0..605709b6eecb 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -66,6 +66,7 @@ config ARM
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select HARDIRQS_SW_RESEND
+	select HAS_IOPORT
 	select HAVE_ARCH_AUDITSYSCALL if AEABI && !OABI_COMPAT
 	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c4207cf9bb17..a8b199a40c8f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -135,6 +135,7 @@ config ARM64
 	select GENERIC_GETTIMEOFDAY
 	select GENERIC_VDSO_TIME_NS
 	select HARDIRQS_SW_RESEND
+	select HAS_IOPORT
 	select HAVE_MOVE_PMD
 	select HAVE_MOVE_PUD
 	select HAVE_PCI
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 1e33666fa679..672aa2a88b19 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -24,6 +24,7 @@ config IA64
 	select PCI_DOMAINS if PCI
 	select PCI_MSI
 	select PCI_SYSCALL if PCI
+	select HAS_IOPORT
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_EXIT_THREAD
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 0b50da08a9c5..926d97c33828 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -16,6 +16,7 @@ config M68K
 	select GENERIC_CPU_DEVICES
 	select GENERIC_IOMAP
 	select GENERIC_IRQ_SHOW
+	select HAS_IOPORT
 	select HAVE_AOUT if MMU
 	select HAVE_ASM_MODVERSIONS
 	select HAVE_DEBUG_BUGVERBOSE
diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 59798e43cdb0..213ef2940079 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -21,6 +21,7 @@ config MICROBLAZE
 	select GENERIC_IRQ_SHOW
 	select GENERIC_PCI_IOMAP
 	select GENERIC_SCHED_CLOCK
+	select HAS_IOPORT if PCI
 	select HAVE_ARCH_HASH
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 0215dc1529e9..87e6e7c29493 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -47,6 +47,7 @@ config MIPS
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select GUP_GET_PTE_LOW_HIGH if CPU_MIPS32 && PHYS_ADDR_T_64BIT
+	select HAS_IOPORT
 	select HAVE_ARCH_COMPILER_H
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KGDB if MIPS_FP_SUPPORT
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 011dc32fdb4d..b352c6dbbead 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -43,6 +43,7 @@ config PARISC
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS
 	select TTY # Needed for pdc_cons.c
+	select HAS_IOPORT if PCI || EISA
 	select HAVE_DEBUG_STACKOVERFLOW
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HASH
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index dea74d7717c0..d39ba34d839a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -185,6 +185,7 @@ config PPC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL
 	select GENERIC_VDSO_TIME_NS
+	select HAS_IOPORT			if PCI
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
 	select HAVE_ARCH_HUGE_VMAP		if PPC_RADIX_MMU || PPC_8xx
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 821252b65f89..b69cc86522fb 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -63,6 +63,7 @@ config RISCV
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_TIME_VSYSCALL if MMU && 64BIT
 	select GENERIC_VDSO_TIME_NS if HAVE_GENERIC_VDSO
+	select HAS_IOPORT if MMU
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
 	select HAVE_ARCH_JUMP_LABEL_RELATIVE if !XIP_KERNEL
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 70afb30e0b32..334a52535379 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -24,6 +24,7 @@ config SUPERH
 	select GENERIC_SCHED_CLOCK
 	select GENERIC_SMP_IDLE_THREAD
 	select GUP_GET_PTE_LOW_HIGH if X2TLB
+	select HAS_IOPORT if HAS_IOPORT_MAP
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 66fc08646be5..728598673724 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -32,6 +32,7 @@ config SPARC
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select GENERIC_PCI_IOMAP
+	select HAS_IOPORT
 	select HAVE_NMI_WATCHDOG if SPARC64
 	select HAVE_CBPF_JIT if SPARC32
 	select HAVE_EBPF_JIT if SPARC64
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5c2ccb85f2ef..8d3cfd693559 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -153,6 +153,7 @@ config X86
 	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
 	select HARDIRQS_SW_RESEND
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
+	select HAS_IOPORT
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
 	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 3c68e174a113..a61285100224 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -81,7 +81,7 @@ config MOXTET
 config HISILICON_LPC
 	bool "Support for ISA I/O space on HiSilicon Hip06/7"
 	depends on (ARM64 && ARCH_HISI) || (COMPILE_TEST && !ALPHA && !HEXAGON && !PARISC)
-	depends on HAS_IOMEM
+	depends on HAS_IOPORT
 	select INDIRECT_PIO if ARM64
 	help
 	  Driver to enable I/O access to devices attached to the Low Pin
diff --git a/lib/Kconfig b/lib/Kconfig
index 5e7165e6a346..e55746625762 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -95,6 +95,7 @@ config ARCH_USE_SYM_ANNOTATIONS
 config INDIRECT_PIO
 	bool "Access I/O in non-MMIO mode"
 	depends on ARM64
+	depends on HAS_IOPORT
 	help
 	  On some platforms where no separate I/O space exists, there are I/O
 	  hosts which can not be accessed in MMIO mode. Using the logical PIO
@@ -486,6 +487,9 @@ config HAS_IOMEM
 	depends on !NO_IOMEM
 	default y
 
+config HAS_IOPORT
+	def_bool ISA || LEGACY_PCI
+
 config HAS_IOPORT_MAP
 	bool
 	depends on HAS_IOMEM && !NO_IOPORT_MAP
diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb
index 05dae05b6cc9..c68e4d9dcecb 100644
--- a/lib/Kconfig.kgdb
+++ b/lib/Kconfig.kgdb
@@ -121,6 +121,7 @@ config KDB_DEFAULT_ENABLE
 
 config KDB_KEYBOARD
 	bool "KGDB_KDB: keyboard as input device"
+	depends on HAS_IOPORT
 	depends on VT && KGDB_KDB
 	default n
 	help
-- 
2.32.0


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