Message ID | 20230314121216.413434-1-schnelle@linux.ibm.com (mailing list archive) |
---|---|
Headers | show |
Series | Kconfig: Introduce HAS_IOPORT config option | expand |
On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote: > --- a/arch/um/Kconfig > +++ b/arch/um/Kconfig > @@ -56,6 +56,7 @@ config NO_IOPORT_MAP > > config ISA > bool > + depends on HAS_IOPORT > config ISA here is already unselectable, and nothing ever does "select ISA" (only in some other architectures), so is there much point in this? I'm not even sure why this exists at all. But anyway, adding a dependency to a always-false symbol doesn't make it less always-false :-) Acked-by: Johannes Berg <johannes@sipsolutions.net> # for ARCH=um Certainly will be nice to get rid of this cruft for architectures that don't have it. johannes
On Tue, Mar 14, 2023 at 1:13 PM Niklas Schnelle <schnelle@linux.ibm.com> wrote: > We introduce a new HAS_IOPORT Kconfig option to indicate 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 such as s390. Also > add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options > as these busses always go along with HAS_IOPORT. > > The "depends on" relations 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. > > Co-developed-by: Arnd Bergmann <arnd@kernel.org> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > arch/m68k/Kconfig | 1 + Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Gr{oetje,eeting}s, Geert
On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote: > We introduce a new HAS_IOPORT Kconfig option to indicate 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 such as s390. Also > add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options > as these busses always go along with HAS_IOPORT. > > The "depends on" relations 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. I think it would be helpful to enumerate which architectures do not get HAS_IOPORT added, as they will be affected more. > Co-developed-by: Arnd Bergmann <arnd@kernel.org> > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> If there are no objections, I could send this first patch for the asm-generic tree as a preparation for 6.3, so we are able to merge the other patches through subsystem maintainer tree for 6.4. arch/loongarch/ will now also need to select HAS_IOPORT uncontitionally, this architecture was added after you sent v2. > diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig > index a98940e64243..5eeacc72e4da 100644 > --- a/arch/parisc/Kconfig > +++ b/arch/parisc/Kconfig > @@ -47,6 +47,7 @@ config PARISC > select MODULES_USE_ELF_RELA > select CLONE_BACKWARDS > select TTY # Needed for pdc_cons.c > + select HAS_IOPORT if PCI It's also needed for EISA and I think you should select it from CONFIG_GSC in drivers/parisc/Kconfig for this purpose. This could also be 'select HAS_IOPORT if PCI || EISA', but that would require removing the 'depends on HAS_IOPORT' under drivers/eisa/. > select HAVE_DEBUG_STACKOVERFLOW > select HAVE_ARCH_AUDITSYSCALL > select HAVE_ARCH_HASH > @@ -131,6 +132,7 @@ config STACKTRACE_SUPPORT > > config ISA_DMA_API > bool > + depends on HAS_IOPORT > This line is not really needed since there is no way to enable ISA_DMA_API. > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index a6c4407d3ec8..f7de646c074a 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -188,6 +188,7 @@ 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 > @@ -1070,7 +1071,6 @@ menu "Bus options" > > config ISA > bool "Support for ISA-bus hardware" > - depends on PPC_CHRP > select PPC_I8259 > help > Find out whether you have ISA slots on your motherboard. ISA is the This line looks wrong, I think we should keep that dependency. Did you get a circular dependency if you leave it in? > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index a825bf031f49..634dd42532f3 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -162,6 +162,7 @@ config X86 > select GUP_GET_PXX_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 > @@ -2893,6 +2894,7 @@ if X86_32 > > config ISA > bool "ISA support" > + depends on HAS_IOPORT > help HAS_IOPORT is selected unconditionally already, so this doesn't really do anything. > diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb > index 3b9a44008433..c68e4d9dcecb 100644 > --- a/lib/Kconfig.kgdb > +++ b/lib/Kconfig.kgdb > @@ -121,7 +121,8 @@ config KDB_DEFAULT_ENABLE > > config KDB_KEYBOARD > bool "KGDB_KDB: keyboard as input device" > - depends on VT && KGDB_KDB && !PARISC > + depends on HAS_IOPORT > + depends on VT && KGDB_KDB > default n This loses the !PARISC dependency, which I don't think is intentional. The added HAS_IOPORT dependency makes sense here, but I think this should be in a different patch and not in the preparation. Arnd
On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote: > Hello Kernel Hackers, > > Some platforms such as s390 do not support PCI I/O spaces. On such platforms > I/O space accessors like inb()/outb() are stubs that can never actually work. > The way these stubs are implemented in asm-generic/io.h leads to compiler > warnings because any use will be a NULL pointer access on these platforms. In > a previous patch we tried handling this with a run-time warning on access. This > approach however was rejected by Linus[0] with the argument that this really > should be a compile-time check and, though a much more invasive change, we > believe that is indeed the right approach. > > This patch series aims to do exactly that by introducing a HAS_IOPORT config > option akin to the existing HAS_IOMEM. When this is unset inb()/outb() and > friends may not be defined. This is also the same approach originally planned by > Uwe Kleine-König as mentioned in commit ce816fa88cca ("Kconfig: rename > HAS_IOPORT to HAS_IOPORT_MAP"). > > This series builds heavily on an original patch for demonstating the concept by > Arnd Bergmann[1] and incoporates feedback of previous RFC versions [2] and [3]. > > This version is based on v6.3-rc1 and is also available on my kernel.org tree > in the has_ioport_v3 branch with the PGP signed tag has_ioport_v3_signed: > > https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git Thanks a lot for the rebase, hopefully we can finally get this merged. I'll go through all patches and note everything I spot that should be improved. I'd like to make sure that at least the first patch can get merged quickly so we can continue on the rest. Since this is all related to asm-generic/io.h and cross-architecture work, I can pick up anything that has nobody else maintaining it through the asm-generic tree. Arnd
On Tue, 2023-03-14 at 14:29 +0100, Arnd Bergmann wrote: > On Tue, Mar 14, 2023, at 13:11, Niklas Schnelle wrote: > > We introduce a new HAS_IOPORT Kconfig option to indicate 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 such as s390. Also > > add dependencies on HAS_IOPORT for the ISA and HAVE_EISA config options > > as these busses always go along with HAS_IOPORT. > > > > The "depends on" relations 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. > > I think it would be helpful to enumerate which architectures > do not get HAS_IOPORT added, as they will be affected more. > > > Co-developed-by: Arnd Bergmann <arnd@kernel.org> > > Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> > > If there are no objections, I could send this first patch for the > asm-generic tree as a preparation for 6.3, so we are able to merge > the other patches through subsystem maintainer tree for 6.4. > > arch/loongarch/ will now also need to select HAS_IOPORT > uncontitionally, this architecture was added after you > sent v2. Ah right. Added "select HAS_IOPORT" for LoongArch. > > > diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig > > index a98940e64243..5eeacc72e4da 100644 > > --- a/arch/parisc/Kconfig > > +++ b/arch/parisc/Kconfig > > @@ -47,6 +47,7 @@ config PARISC > > select MODULES_USE_ELF_RELA > > select CLONE_BACKWARDS > > select TTY # Needed for pdc_cons.c > > + select HAS_IOPORT if PCI > > It's also needed for EISA and I think you should select it > from CONFIG_GSC in drivers/parisc/Kconfig for this purpose. > > This could also be 'select HAS_IOPORT if PCI || EISA', but > that would require removing the 'depends on HAS_IOPORT' > under drivers/eisa/. I did use "select HAS_IOPORT if PCI || ISA || ATARI_ROM_ISA" in m68k so I think ideally we would handle both in the same way. I don't have a strong preference but I think the "select HAS_IOPORT if ..." puts it all in a single place which is nice. Also I think this would make it more similar architectures with unconditional HAS_IOPORT that thus don't need "depends on HAS_IOPORT" in their "config ISA" either. As also pointed by your comment below for x86. So will try to go this route. > > > select HAVE_DEBUG_STACKOVERFLOW > > select HAVE_ARCH_AUDITSYSCALL > > select HAVE_ARCH_HASH > > @@ -131,6 +132,7 @@ config STACKTRACE_SUPPORT > > > > config ISA_DMA_API > > bool > > + depends on HAS_IOPORT > > > > This line is not really needed since there is no way to > enable ISA_DMA_API. Removed > > > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > > index a6c4407d3ec8..f7de646c074a 100644 > > --- a/arch/powerpc/Kconfig > > +++ b/arch/powerpc/Kconfig > > @@ -188,6 +188,7 @@ 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 > > @@ -1070,7 +1071,6 @@ menu "Bus options" > > > > config ISA > > bool "Support for ISA-bus hardware" > > - depends on PPC_CHRP > > select PPC_I8259 > > help > > Find out whether you have ISA slots on your motherboard. ISA is the > > This line looks wrong, I think we should keep that dependency. > Did you get a circular dependency if you leave it in? I don't recall why this was removed. I guess it happened when I was experimenting with adding "depends on HAS_IOPORT" for the ISA config options but that ultimately lead to circular dependencies, must have messed up when removing this here. > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index a825bf031f49..634dd42532f3 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -162,6 +162,7 @@ config X86 > > select GUP_GET_PXX_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 > > @@ -2893,6 +2894,7 @@ if X86_32 > > > > config ISA > > bool "ISA support" > > + depends on HAS_IOPORT > > help > > HAS_IOPORT is selected unconditionally already, so this doesn't > really do anything. Removed. > > > diff --git a/lib/Kconfig.kgdb b/lib/Kconfig.kgdb > > index 3b9a44008433..c68e4d9dcecb 100644 > > --- a/lib/Kconfig.kgdb > > +++ b/lib/Kconfig.kgdb > > @@ -121,7 +121,8 @@ config KDB_DEFAULT_ENABLE > > > > config KDB_KEYBOARD > > bool "KGDB_KDB: keyboard as input device" > > - depends on VT && KGDB_KDB && !PARISC > > + depends on HAS_IOPORT > > + depends on VT && KGDB_KDB > > default n > > This loses the !PARISC dependency, which I don't think is > intentional. The added HAS_IOPORT dependency makes sense > here, but I think this should be in a different patch > and not in the preparation. > > Arnd Agree will put into its own patch and re-add the !PARISC
On Tue, 2023-03-14 at 13:37 +0100, Johannes Berg wrote: > On Tue, 2023-03-14 at 13:11 +0100, Niklas Schnelle wrote: > > --- a/arch/um/Kconfig > > +++ b/arch/um/Kconfig > > @@ -56,6 +56,7 @@ config NO_IOPORT_MAP > > > > config ISA > > bool > > + depends on HAS_IOPORT > > > > config ISA here is already unselectable, and nothing ever does "select > ISA" (only in some other architectures), so is there much point in this? > > I'm not even sure why this exists at all. You're right there's not much point and I dropped this for v4. I agree that probably the whole "config ISA" could be removed if it's always false anyway but that seems out of scope for this patch. > > But anyway, adding a dependency to a always-false symbol doesn't make it > less always-false :-) > > Acked-by: Johannes Berg <johannes@sipsolutions.net> # for ARCH=um Thanks > > > Certainly will be nice to get rid of this cruft for architectures that > don't have it. > > johannes Yes, also, for s390 the broken NULL + port number access in the generic inb()/outb() currently causes the only remaining clang warning on defconfig builds.