linux.git/drivers/char/Kconfig, branch v5.13

drivers/char: remove /dev/kmem for good

2021-05-07T07:26:34+00:00

Patch series "drivers/char: remove /dev/kmem for good".

Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existence of /dev/kmem.

Comparing it with the /proc/kcore implementation, it does not seem to be
able to deal with things like

a) Pages unmapped from the direct mapping (e.g., to be used by secretmem)
  -> kern_addr_valid(). virt_addr_valid() is not sufficient.

b) Special cases like gart aperture memory that is not to be touched
  -> mem_pfn_is_ram()

Unless I am missing something, it's at least broken in some cases and might
fault/crash the machine.

Looks like its existence has been questioned before in 2005 and 2010 [1],
after ~11 additional years, it might make sense to revive the discussion.

CONFIG_DEVKMEM is only enabled in a single defconfig (on purpose or by
mistake?).  All distributions disable it: in Ubuntu it has been disabled
for more than 10 years, in Debian since 2.6.31, in Fedora at least
starting with FC3, in RHEL starting with RHEL4, in SUSE starting from
15sp2, and OpenSUSE has it disabled as well.

1) /dev/kmem was popular for rootkits [2] before it got disabled
   basically everywhere. Ubuntu documents [3] "There is no modern user of
   /dev/kmem any more beyond attackers using it to load kernel rootkits.".
   RHEL documents in a BZ [5] "it served no practical purpose other than to
   serve as a potential security problem or to enable binary module drivers
   to access structures/functions they shouldn't be touching"

2) /proc/kcore is a decent interface to have a controlled way to read
   kernel memory for debugging puposes. (will need some extensions to
   deal with memory offlining/unplug, memory ballooning, and poisoned
   pages, though)

3) It might be useful for corner case debugging [1]. KDB/KGDB might be a
   better fit, especially, to write random memory; harder to shoot
   yourself into the foot.

4) "Kernel Memory Editor" [4] hasn't seen any updates since 2000 and seems
   to be incompatible with 64bit [1]. For educational purposes,
   /proc/kcore might be used to monitor value updates -- or older
   kernels can be used.

5) It's broken on arm64, and therefore, completely disabled there.

Looks like it's essentially unused and has been replaced by better
suited interfaces for individual tasks (/proc/kcore, KDB/KGDB). Let's
just remove it.

[1] https://lwn.net/Articles/147901/
[2] https://www.linuxjournal.com/article/10505
[3] https://wiki.ubuntu.com/Security/Features#A.2Fdev.2Fkmem_disabled
[4] https://sourceforge.net/projects/kme/
[5] https://bugzilla.redhat.com/show_bug.cgi?id=154796

Link: https://lkml.kernel.org/r/20210324102351.6932-1-david@redhat.com
Link: https://lkml.kernel.org/r/20210324102351.6932-2-david@redhat.com
Signed-off-by: David Hildenbrand 
Acked-by: Michal Hocko 
Acked-by: Kees Cook 
Cc: Linus Torvalds 
Cc: Greg Kroah-Hartman 
Cc: "Alexander A. Klimov" 
Cc: Alexander Viro 
Cc: Alexandre Belloni 
Cc: Andrew Lunn 
Cc: Andrey Zhizhikin 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Brian Cain 
Cc: Christian Borntraeger 
Cc: Christophe Leroy 
Cc: Chris Zankel 
Cc: Corentin Labbe 
Cc: "David S. Miller" 
Cc: "Eric W. Biederman" 
Cc: Geert Uytterhoeven 
Cc: Gerald Schaefer 
Cc: Greentime Hu 
Cc: Gregory Clement 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: Hillf Danton 
Cc: huang ying 
Cc: Ingo Molnar 
Cc: Ivan Kokshaysky 
Cc: "James E.J. Bottomley" 
Cc: James Troup 
Cc: Jiaxun Yang 
Cc: Jonas Bonn 
Cc: Jonathan Corbet 
Cc: Kairui Song 
Cc: Krzysztof Kozlowski 
Cc: Kuninori Morimoto 
Cc: Liviu Dudau 
Cc: Lorenzo Pieralisi 
Cc: Luc Van Oostenryck 
Cc: Luis Chamberlain 
Cc: Matthew Wilcox 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Mike Rapoport 
Cc: Mikulas Patocka 
Cc: Minchan Kim 
Cc: Niklas Schnelle 
Cc: Oleksiy Avramchenko 
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt 
Cc: Paul Mackerras 
Cc: "Pavel Machek (CIP)" 
Cc: Pavel Machek 
Cc: "Peter Zijlstra (Intel)" 
Cc: Pierre Morel 
Cc: Randy Dunlap 
Cc: Richard Henderson 
Cc: Rich Felker 
Cc: Robert Richter 
Cc: Rob Herring 
Cc: Russell King 
Cc: Sam Ravnborg 
Cc: Sebastian Andrzej Siewior 
Cc: Sebastian Hesselbarth 
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne 
Cc: Stefan Kristiansson 
Cc: Steven Rostedt 
Cc: Sudeep Holla 
Cc: Theodore Dubois 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Viresh Kumar 
Cc: William Cohen 
Cc: Xiaoming Ni 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

char: virtio: Select VIRTIO from VIRTIO_CONSOLE.

2020-09-07T12:32:40+00:00

Make it possible to have virtio console built-in when
other virtio drivers are modular.

Signed-off-by: Michal Suchanek 
Reviewed-by: Amit Shah 
Link: https://lore.kernel.org/r/20200831165850.26163-1-msuchanek@suse.de
Signed-off-by: Greg Kroah-Hartman

char: Replace HTTP links with HTTPS ones

2020-07-23T07:44:15+00:00

Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
	  If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
            If both the HTTP and HTTPS versions
            return 200 OK and serve the same content:
              Replace HTTP with HTTPS.

Signed-off-by: Alexander A. Klimov 
Link: https://lore.kernel.org/r/20200713104453.33414-1-grandmaster@al2klimov.de
Signed-off-by: Greg Kroah-Hartman

treewide: replace '---help---' in Kconfig files with 'help'

2020-06-13T16:57:21+00:00

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.

This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.

There are a variety of indentation styles found.

  a) 4 spaces + '---help---'
  b) 7 spaces + '---help---'
  c) 8 spaces + '---help---'
  d) 1 space + 1 tab + '---help---'
  e) 1 tab + '---help---'    (correct indentation)
  f) 1 tab + 1 space + '---help---'
  g) 1 tab + 2 spaces + '---help---'

In order to convert all of them to 1 tab + 'help', I ran the
following commend:

  $ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'

Signed-off-by: Masahiro Yamada

powerpc: Remove Xilinx PPC405/PPC440 support

2020-05-28T13:24:34+00:00

The latest Xilinx design tools called ISE and EDK has been released in
October 2013. New tool doesn't support any PPC405/PPC440 new designs.
These platforms are no longer supported and tested.

PowerPC 405/440 port is orphan from 2013 by
commit cdeb89943bfc ("MAINTAINERS: Fix incorrect status tag") and
commit 19624236cce1 ("MAINTAINERS: Update Grant's email address and maintainership")
that's why it is time to remove the support fot these platforms.

Signed-off-by: Michal Simek 
Signed-off-by: Christophe Leroy 
Acked-by: Arnd Bergmann 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/8c593895e2cb57d232d85ce4d8c3a1aa7f0869cc.1590079968.git.christophe.leroy@csgroup.eu

Merge tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random

2020-04-05T17:59:18+00:00

Pull /dev/random updates from Ted Ts'o:

 - Improve getrandom and /dev/random's support for those arm64
   architecture variants that have RNG instructions.

 - Use batched output from CRNG instead of CPU's RNG instructions for
   better performance.

 - Miscellaneous bug fixes.

* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
  random: avoid warnings for !CONFIG_NUMA builds
  random: fix data races at timer_rand_state
  random: always use batched entropy for get_random_u{32,64}
  random: Make RANDOM_TRUST_CPU depend on ARCH_RANDOM
  arm64: add credited/trusted RNG support
  random: add arch_get_random_*long_early()
  random: split primary/secondary crng init paths

rtc/alpha: remove legacy rtc driver

2020-03-19T06:41:02+00:00

The old drivers/char/rtc.c driver was originally the implementation
for x86 PCs but got subsequently replaced by the rtc class driver
on all architectures except alpha.

Move alpha over to the portable driver and remove the old one
for good.

The CONFIG_JS_RTC option was only ever used on SPARC32 but
has not been available for many years, this was used to build
the same rtc driver with a different module name.

Cc: Richard Henderson 
Cc: Ivan Kokshaysky 
Cc: Matt Turner 
Cc: linux-alpha@vger.kernel.org
Cc: Paul Gortmaker 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20200226224322.187960-2-alexandre.belloni@bootlin.com
Signed-off-by: Greg Kroah-Hartman

rtc/ia64: remove legacy efirtc driver

2020-03-19T06:41:02+00:00

There are two EFI RTC drivers, the original drivers/char/efirtc.c
driver and the more modern drivers/rtc/rtc-efi.c.

Both implement the same interface, but the new one does so
in a more portable way.

Move everything over to that one and remove the old one.

Cc: linux-ia64@vger.kernel.org
Cc: Fenghua Yu 
Cc: Tony Luck 
Cc: Stephane Eranian 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Alexandre Belloni 
Link: https://lore.kernel.org/r/20200226224322.187960-1-alexandre.belloni@bootlin.com
Signed-off-by: Greg Kroah-Hartman

tty: source all tty Kconfig files in one place

2020-03-12T16:17:30+00:00

'source' (include) all of the tty/*/Kconfig files from
drivers/tty/Kconfig instead of from drivers/char/Kconfig.
This consolidates them both in source code and in menu
presentation to the user.

Move hvc/Kconfig and serial/Kconfig 'source' lines into the
if TTY/endif block and remove the if TTY/endif blocks from
those 2 files.

Cc: linux-serial@vger.kernel.org
Cc: Jiri Slaby 
Cc: Greg Kroah-Hartman 
Cc: Arnd Bergmann 
Suggested-by: Jiri Slaby 
Suggested-by: Arnd Bergmann 
Acked-by: Arnd Bergmann 
Signed-off-by: Randy Dunlap 
Link: https://lore.kernel.org/r/20200311225736.32147-3-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman

char: group dev configs togther

2020-03-12T16:17:29+00:00

Group /dev/{mem,kmem,nvram,raw,port} driver configs together.
This also means that tty configs are now grouped together instead
of being split up.

This just moves Kconfig lines around. There are no other changes.

Cc: linux-serial@vger.kernel.org
Cc: Jiri Slaby 
Cc: Greg Kroah-Hartman 
Cc: Arnd Bergmann 
Acked-by: Arnd Bergmann 
Signed-off-by: Randy Dunlap 
Link: https://lore.kernel.org/r/20200311225736.32147-2-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman