[PATCH v5 00/44] treewide: Remove I/O port accessors for HAS_IOPORT=n

Niklas Schnelle
2023-05-22T10:51:49Z

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 does exactly that by utilizing the HAS_IOPORT Kconfig option
introduced in v6.4-rc1 via the spun out first patch[1] of a previous version. With
the final patch of this series HAS_IOPORT=n means that inb()/outb() and friends
are not 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"). With the HAS_IOPORT Kconfig option merged already
per-subsystem patches can now also be merged independently and only the last
patch needs to wait.

This series builds heavily on an original patch for demonstating the concept by
Arnd Bergmann[2] and incoporates feedback of previous versions [3][4][5][6].

A few patches have already been applied but I've kept those which are not yet
in v6.4-rc3.

This version is based on v6.4-rc3 and is also available on my kernel.org tree
in the has_ioport_v5:

https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git

Thanks,
Niklas Schnelle

Changes froom v4:
- Rebased on v6.4-rc3
- ata: Moved #ifdef CONFIG_PATA_ALI into ata_pci_bmdma_clear_simplex()
(Damien Le Moal)
- char: Fixed ipmi typo and split the char subsystem patch into 3 parts for
char, tpm, and ipmi (Greg K-H)
- rtc: Added missing "|| MACH_DECSTATION" (Maciej W. Rozycki)
- usb: Made UHCI_OUT() empty variant "do {} while (0)" and removed unneeded
unconditional UHCI_IN() / UHCI_OUT() uses (Arnd, Alan Stern, Greg K-H)
- usb: pci-quirks: Added missing USB_PCI dependency
- video: Split into vgacon and fbdev patches
- Removed atyfb patch as it was merged in v6.4-rc3

Changes from v3:
- Rebased on v6.4-rc2 which includes the Kconfig HAS_IOPORT option
- Fixed some wrong #ifdef HAS_IOPORT to #ifdef CONFIG_HAS_IOPORT
- Split the usb subsystem patch into 3 parts (Arnd)
- Removed unneeded HAS_IOPORT dependency for SERIO_PARKBD (Geert Uytterhoeven)
- Removed no-op I/O access from FB_ATY (Ville Syrjälä)
- Simplified HAS_IOPORT dependencies for the sound subsystem (Takashi Iwai)
- Slightly reworded the subject line of the last patch which removes
the I/O port accessor functions.

Changes from RFC v2:
- Rebased on v6.3-rc1
- Fixed a NULL pointer dereference in set_io_from_upio() due to accidentially
expanded #ifdef CONFIG_SERIAL_8250_RT288X (kernel test robot)
- Dropped "ACPI: add dependency on HAS_IOPORT" (Bjorn Helgaas)
- Reworded commit message and moved ifdefs for "PCI/sysfs: Make I/O resource
depend on HAS_IOPORT" (Bjorn Helgaas)
- Instead of complete removal inb() etc. are marked with __compiletime_error()
when HAS_IOPORT is unset allowing for better error reporting (Ahmad Fatoum)
- Removed HAS_IOPORT dependency from PCMCIA as I/O port use is optional in at
least PC Card. Instead added HAS_IOPORT on a per driver basis. (Bjorn
Helgaas)
- Made uhci_has_pci_registers() constant 0 if HAS_IOPORT is not defined (Alan
Stern)

Changes from RFC v1:
- Completely dropped the LEGACY_PCI option and replaced its dependencies with
HAS_IOPORT as appropriate
- In the usb subsystem patch I incorporated the feedback from v1 by Alan Stern:
- Used a local macro to nop in*()/out*() in the helpers
- Removed an unnecessary further restriction on CONFIG_USB_UHCI_HCD
- Added a few more subsystems including wireless, ptp, and, mISDN that I had
previously missed due to a blanket !S390.
- Removed blanket !S390 dependencies where they are added due to the I/O port
problem
- In the sound system SND_OPL3_LIB needed to use "depends on" instead of
"select" because of its added HAS_IOPORT dependency
- In the drm subsystem the bochs driver gets #ifdefs instead of a blanket
dependency because its MMIO capable device variant should work without
HAS_IOPORT.

[0] https://lore.kernel.org/lkml/CAHk-=wg80je=K7madF4e7WrRNp37e3qh6y10Svhdc7O8SZ_-8g@mail.gmail.com/
[1] https://lore.kernel.org/lkml/20230323163354.1454196-1-schnelle@linux.ibm.com/
[2] https://lore.kernel.org/lkml/CAK8P3a0MNbx-iuzW_-=0ab6-TTZzwV-PT_6gAC1Gp5PgYyHcrA@mail.gmail.com/
[3] https://yhbt.net/lore/all/20211227164317.4146918-1-schnelle@linux.ibm.com/
[4] https://lore.kernel.org/all/20220429135108.2781579-1-schnelle@linux.ibm.com/
[5] https://lore.kernel.org/lkml/20230314121216.413434-1-schnelle@linux.ibm.com/
[6] https://lore.kernel.org/all/20230516110038.2413224-1-schnelle@linux.ibm.com/

Niklas Schnelle (44):
kgdb: add HAS_IOPORT dependency
ata: add HAS_IOPORT dependencies
char: add HAS_IOPORT dependencies
char: ipmi: handle HAS_IOPORT dependencies
char: tpm: handle HAS_IOPORT dependencies
comedi: add HAS_IOPORT dependencies
counter: add HAS_IOPORT_MAP dependency
/dev/port: don't compile file operations without CONFIG_DEVPORT
drm: handle HAS_IOPORT dependencies
firmware: dmi-sysfs: handle HAS_IOPORT=n
gpio: add HAS_IOPORT dependencies
hwmon: add HAS_IOPORT dependencies
i2c: add HAS_IOPORT dependencies
iio: ad7606: Kconfig: add HAS_IOPORT dependencies
Input: add HAS_IOPORT dependencies
Input: gameport: add ISA and HAS_IOPORT dependencies
leds: add HAS_IOPORT dependencies
media: add HAS_IOPORT dependencies
misc: add HAS_IOPORT dependencies
mISDN: add HAS_IOPORT dependencies
mpt fusion: add HAS_IOPORT dependencies
net: handle HAS_IOPORT dependencies
parport: PC style parport depends on HAS_IOPORT
PCI: Make quirk using inw() depend on HAS_IOPORT
PCI/sysfs: Make I/O resource depend on HAS_IOPORT
pcmcia: add HAS_IOPORT dependencies
platform: add HAS_IOPORT dependencies
pnp: add HAS_IOPORT dependencies
power: add HAS_IOPORT dependencies
rtc: add HAS_IOPORT dependencies
scsi: add HAS_IOPORT dependencies
sound: add HAS_IOPORT dependencies
speakup: add HAS_IOPORT dependency for SPEAKUP_SERIALIO
staging: add HAS_IOPORT dependencies
tty: serial: handle HAS_IOPORT dependencies
usb: add HAS_IOPORT dependencies
usb: uhci: handle HAS_IOPORT dependencies
usb: pci-quirks: handle HAS_IOPORT dependencies
vgacon: add HAS_IOPORT dependencies
fbdev: add HAS_IOPORT dependencies
video: Handle HAS_IOPORT dependencies
watchdog: add HAS_IOPORT dependencies
wireless: add HAS_IOPORT dependencies
asm-generic/io.h: Remove I/O port accessors for HAS_IOPORT=n

drivers/accessibility/speakup/Kconfig | 1 +
drivers/ata/Kconfig | 28 ++---
drivers/ata/libata-sff.c | 4 +
drivers/char/Kconfig | 3 +-
drivers/char/ipmi/Makefile | 11 +-
drivers/char/ipmi/ipmi_si_intf.c | 3 +-
drivers/char/ipmi/ipmi_si_pci.c | 3 +
drivers/char/mem.c | 6 +-
drivers/char/tpm/Kconfig | 1 +
drivers/char/tpm/tpm_infineon.c | 16 ++-
drivers/char/tpm/tpm_tis_core.c | 19 ++-
drivers/comedi/Kconfig | 103 +++++++++------
drivers/counter/Kconfig | 1 +
drivers/firmware/dmi-sysfs.c | 4 +
drivers/gpio/Kconfig | 26 ++--
drivers/gpu/drm/qxl/Kconfig | 1 +
drivers/gpu/drm/tiny/bochs.c | 17 +++
drivers/gpu/drm/tiny/cirrus.c | 2 +
drivers/hwmon/Kconfig | 21 +++-
drivers/i2c/busses/Kconfig | 31 ++---
drivers/iio/adc/Kconfig | 2 +-
drivers/input/gameport/Kconfig | 4 +-
drivers/input/serio/Kconfig | 1 +
drivers/input/touchscreen/Kconfig | 1 +
drivers/isdn/Kconfig | 1 -
drivers/isdn/hardware/mISDN/Kconfig | 12 +-
drivers/leds/Kconfig | 2 +-
drivers/media/pci/dm1105/Kconfig | 2 +-
drivers/media/radio/Kconfig | 14 ++-
drivers/media/rc/Kconfig | 6 +
drivers/message/fusion/Kconfig | 2 +-
drivers/misc/altera-stapl/Makefile | 3 +-
drivers/misc/altera-stapl/altera.c | 6 +-
drivers/net/Kconfig | 2 +-
drivers/net/arcnet/Kconfig | 2 +-
drivers/net/can/cc770/Kconfig | 1 +
drivers/net/can/sja1000/Kconfig | 1 +
drivers/net/ethernet/3com/Kconfig | 4 +-
drivers/net/ethernet/8390/Kconfig | 6 +-
drivers/net/ethernet/amd/Kconfig | 4 +-
drivers/net/ethernet/fujitsu/Kconfig | 2 +-
drivers/net/ethernet/intel/Kconfig | 2 +-
drivers/net/ethernet/sis/Kconfig | 4 +-
drivers/net/ethernet/smsc/Kconfig | 2 +-
drivers/net/ethernet/ti/Kconfig | 2 +-
drivers/net/ethernet/via/Kconfig | 1 +
drivers/net/ethernet/xircom/Kconfig | 2 +-
drivers/net/fddi/defxx.c | 2 +-
drivers/net/hamradio/Kconfig | 6 +-
drivers/net/wan/Kconfig | 2 +-
drivers/net/wireless/atmel/Kconfig | 2 +-
drivers/net/wireless/intersil/hostap/Kconfig | 2 +-
drivers/parport/Kconfig | 3 +-
drivers/pci/pci-sysfs.c | 4 +
drivers/pci/quirks.c | 2 +
drivers/pcmcia/Kconfig | 5 +-
drivers/platform/chrome/Kconfig | 1 +
drivers/platform/chrome/wilco_ec/Kconfig | 1 +
drivers/pnp/isapnp/Kconfig | 2 +-
drivers/power/reset/Kconfig | 1 +
drivers/rtc/Kconfig | 4 +-
drivers/scsi/Kconfig | 25 ++--
drivers/scsi/aic7xxx/Kconfig.aic79xx | 2 +-
drivers/scsi/aic7xxx/Kconfig.aic7xxx | 2 +-
drivers/scsi/aic94xx/Kconfig | 2 +-
drivers/scsi/megaraid/Kconfig.megaraid | 6 +-
drivers/scsi/mvsas/Kconfig | 2 +-
drivers/scsi/pcmcia/Kconfig | 6 +-
drivers/scsi/qla2xxx/Kconfig | 2 +-
drivers/staging/sm750fb/Kconfig | 2 +-
drivers/staging/vt6655/Kconfig | 2 +-
drivers/tty/Kconfig | 4 +-
drivers/tty/serial/8250/8250_early.c | 4 +
drivers/tty/serial/8250/8250_pci.c | 14 +++
drivers/tty/serial/8250/8250_port.c | 44 +++++--
drivers/tty/serial/8250/Kconfig | 5 +-
drivers/tty/serial/Kconfig | 2 +-
drivers/usb/Kconfig | 10 ++
drivers/usb/core/hcd-pci.c | 2 +
drivers/usb/host/Kconfig | 4 +-
drivers/usb/host/pci-quirks.c | 125 ++++++++++---------
drivers/usb/host/pci-quirks.h | 30 +++--
drivers/usb/host/uhci-hcd.c | 2 +-
drivers/usb/host/uhci-hcd.h | 24 ++--
drivers/video/console/Kconfig | 1 +
drivers/video/fbdev/Kconfig | 22 ++--
drivers/watchdog/Kconfig | 6 +-
include/asm-generic/io.h | 60 +++++++++
include/linux/gameport.h | 9 +-
include/linux/parport.h | 2 +-
include/video/vga.h | 35 ++++--
lib/Kconfig.kgdb | 1 +
net/ax25/Kconfig | 2 +-
sound/drivers/Kconfig | 3 +
sound/isa/Kconfig | 1 +
sound/pci/Kconfig | 45 +++++--
sound/pcmcia/Kconfig | 1 +
97 files changed, 641 insertions(+), 297 deletions(-)

base-commit: 44c026a73be8038f03dbdeef028b642880cf1511
--
2.39.2