[PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[David Hildenbrand]

Let's remove /dev/kmem, which is unused and obsolete. Description from
patch #1:

"
Exploring /dev/kmem and /dev/mem in the context of memory hot(un)plug and
memory ballooning, I started questioning the existance 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 existance 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Looks like it's essentially unused and has been replaced by better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
"

RFC -> v1:
- "drivers/char: remove /dev/kmem for good"
-- Add more details to patch description regarding distributions
- "mm/vmalloc: remove vwrite()"
-- Also remove the nommu variant
- Compile-tested on more archs/configs

David Hildenbrand (3):
  drivers/char: remove /dev/kmem for good
  mm: remove xlate_dev_kmem_ptr()
  mm/vmalloc: remove vwrite()

 Documentation/admin-guide/devices.txt     |   2 +-
 arch/alpha/include/asm/io.h               |   5 -
 arch/arm/configs/dove_defconfig           |   1 -
 arch/arm/configs/magician_defconfig       |   1 -
 arch/arm/configs/moxart_defconfig         |   1 -
 arch/arm/configs/mps2_defconfig           |   1 -
 arch/arm/configs/mvebu_v5_defconfig       |   1 -
 arch/arm/configs/xcep_defconfig           |   1 -
 arch/arm/include/asm/io.h                 |   5 -
 arch/h8300/configs/edosk2674_defconfig    |   1 -
 arch/h8300/configs/h8300h-sim_defconfig   |   1 -
 arch/h8300/configs/h8s-sim_defconfig      |   1 -
 arch/hexagon/configs/comet_defconfig      |   1 -
 arch/hexagon/include/asm/io.h             |   1 -
 arch/ia64/include/asm/io.h                |   1 -
 arch/ia64/include/asm/uaccess.h           |  18 --
 arch/m68k/configs/amcore_defconfig        |   1 -
 arch/m68k/include/asm/io_mm.h             |   5 -
 arch/mips/include/asm/io.h                |   5 -
 arch/openrisc/configs/or1ksim_defconfig   |   1 -
 arch/parisc/include/asm/io.h              |   5 -
 arch/powerpc/include/asm/io.h             |   5 -
 arch/s390/include/asm/io.h                |   5 -
 arch/sh/configs/edosk7705_defconfig       |   1 -
 arch/sh/configs/se7206_defconfig          |   1 -
 arch/sh/configs/sh2007_defconfig          |   1 -
 arch/sh/configs/sh7724_generic_defconfig  |   1 -
 arch/sh/configs/sh7770_generic_defconfig  |   1 -
 arch/sh/configs/sh7785lcr_32bit_defconfig |   1 -
 arch/sh/include/asm/io.h                  |   5 -
 arch/sparc/configs/sparc64_defconfig      |   1 -
 arch/sparc/include/asm/io_64.h            |   5 -
 arch/xtensa/configs/xip_kc705_defconfig   |   1 -
 drivers/char/Kconfig                      |  10 -
 drivers/char/mem.c                        | 231 ----------------------
 include/asm-generic/io.h                  |  11 --
 include/linux/fs.h                        |   2 +-
 include/linux/vmalloc.h                   |   3 +-
 kernel/configs/android-base.config        |   1 -
 mm/ksm.c                                  |   2 +-
 mm/nommu.c                                |  10 -
 mm/vmalloc.c                              | 118 +----------
 42 files changed, 6 insertions(+), 469 deletions(-)


base-commit: 0d02ec6b3136c73c09e7859f0d0e4e2c4c07b49b
-- 
2.29.2

[PATCH v1 1/3] drivers/char: remove /dev/kmem for good

[David Hildenbrand]

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

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Alexander A. Klimov" <grandmaster@al2klimov.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Corentin Labbe <clabbe@baylibre.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Gregory Clement <gregory.clement@bootlin.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hillf Danton <hdanton@sina.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: James Troup <james.troup@canonical.com>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kairui Song <kasong@redhat.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: openrisc@lists.librecores.org
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Pavel Machek (CIP)" <pavel@denx.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Rich Felker <dalias@libc.org>
Cc: Robert Richter <rric@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: sparclinux@vger.kernel.org
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Theodore Dubois <tblodt@icloud.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: uclinux-h8-devel@lists.sourceforge.jp
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: William Cohen <wcohen@redhat.com>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: linux-alpha@vger.kernel.org
Cc: Linux API <linux-api@vger.kernel.org>
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-xtensa@linux-xtensa.org
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 Documentation/admin-guide/devices.txt     |   2 +-
 arch/arm/configs/dove_defconfig           |   1 -
 arch/arm/configs/magician_defconfig       |   1 -
 arch/arm/configs/moxart_defconfig         |   1 -
 arch/arm/configs/mps2_defconfig           |   1 -
 arch/arm/configs/mvebu_v5_defconfig       |   1 -
 arch/arm/configs/xcep_defconfig           |   1 -
 arch/h8300/configs/edosk2674_defconfig    |   1 -
 arch/h8300/configs/h8300h-sim_defconfig   |   1 -
 arch/h8300/configs/h8s-sim_defconfig      |   1 -
 arch/hexagon/configs/comet_defconfig      |   1 -
 arch/m68k/configs/amcore_defconfig        |   1 -
 arch/openrisc/configs/or1ksim_defconfig   |   1 -
 arch/sh/configs/edosk7705_defconfig       |   1 -
 arch/sh/configs/se7206_defconfig          |   1 -
 arch/sh/configs/sh2007_defconfig          |   1 -
 arch/sh/configs/sh7724_generic_defconfig  |   1 -
 arch/sh/configs/sh7770_generic_defconfig  |   1 -
 arch/sh/configs/sh7785lcr_32bit_defconfig |   1 -
 arch/sparc/configs/sparc64_defconfig      |   1 -
 arch/xtensa/configs/xip_kc705_defconfig   |   1 -
 drivers/char/Kconfig                      |  10 -
 drivers/char/mem.c                        | 231 ----------------------
 include/linux/fs.h                        |   2 +-
 include/linux/vmalloc.h                   |   2 +-
 kernel/configs/android-base.config        |   1 -
 mm/ksm.c                                  |   2 +-
 mm/vmalloc.c                              |   2 +-
 28 files changed, 5 insertions(+), 267 deletions(-)

diff --git a/Documentation/admin-guide/devices.txt b/Documentation/admin-guide/devices.txt
index 63fd4e6a014b..beffd5e9130a 100644
--- a/Documentation/admin-guide/devices.txt
+++ b/Documentation/admin-guide/devices.txt
@@ -4,7 +4,7 @@
 
    1 char	Memory devices
 		  1 = /dev/mem		Physical memory access
-		  2 = /dev/kmem		Kernel virtual memory access
+		  2 = /dev/kmem		OBSOLETE - replaced by /proc/kcore
 		  3 = /dev/null		Null device
 		  4 = /dev/port		I/O port access
 		  5 = /dev/zero		Null byte source
diff --git a/arch/arm/configs/dove_defconfig b/arch/arm/configs/dove_defconfig
index e70c997d5f4c..b935162a8bba 100644
--- a/arch/arm/configs/dove_defconfig
+++ b/arch/arm/configs/dove_defconfig
@@ -63,7 +63,6 @@ CONFIG_INPUT_EVDEV=y
 # CONFIG_MOUSE_PS2 is not set
 # CONFIG_SERIO is not set
 CONFIG_LEGACY_PTY_COUNT=16
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_RUNTIME_UARTS=2
diff --git a/arch/arm/configs/magician_defconfig b/arch/arm/configs/magician_defconfig
index b4670d42f378..abde1fb23b20 100644
--- a/arch/arm/configs/magician_defconfig
+++ b/arch/arm/configs/magician_defconfig
@@ -72,7 +72,6 @@ CONFIG_INPUT_TOUCHSCREEN=y
 CONFIG_INPUT_MISC=y
 CONFIG_INPUT_UINPUT=m
 # CONFIG_SERIO is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_PXA=y
 # CONFIG_LEGACY_PTYS is not set
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/arm/configs/moxart_defconfig b/arch/arm/configs/moxart_defconfig
index 6834e97af348..eacc089d86c5 100644
--- a/arch/arm/configs/moxart_defconfig
+++ b/arch/arm/configs/moxart_defconfig
@@ -79,7 +79,6 @@ CONFIG_INPUT_EVBUG=y
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_NR_UARTS=1
diff --git a/arch/arm/configs/mps2_defconfig b/arch/arm/configs/mps2_defconfig
index 1d923dbb9928..89f4a6ff30bd 100644
--- a/arch/arm/configs/mps2_defconfig
+++ b/arch/arm/configs/mps2_defconfig
@@ -69,7 +69,6 @@ CONFIG_SMSC911X=y
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
 CONFIG_SERIAL_NONSTANDARD=y
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_MPS2_UART_CONSOLE=y
 CONFIG_SERIAL_MPS2_UART=y
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/arm/configs/mvebu_v5_defconfig b/arch/arm/configs/mvebu_v5_defconfig
index 4f16716bfc32..d57ff30dabff 100644
--- a/arch/arm/configs/mvebu_v5_defconfig
+++ b/arch/arm/configs/mvebu_v5_defconfig
@@ -100,7 +100,6 @@ CONFIG_INPUT_EVDEV=y
 CONFIG_KEYBOARD_GPIO=y
 # CONFIG_INPUT_MOUSE is not set
 CONFIG_LEGACY_PTY_COUNT=16
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_8250_RUNTIME_UARTS=2
diff --git a/arch/arm/configs/xcep_defconfig b/arch/arm/configs/xcep_defconfig
index f1fbdfc5c8c6..4d8e7f2eaef7 100644
--- a/arch/arm/configs/xcep_defconfig
+++ b/arch/arm/configs/xcep_defconfig
@@ -53,7 +53,6 @@ CONFIG_NET_ETHERNET=y
 # CONFIG_INPUT_KEYBOARD is not set
 # CONFIG_INPUT_MOUSE is not set
 # CONFIG_SERIO is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_PXA=y
 CONFIG_SERIAL_PXA_CONSOLE=y
 # CONFIG_LEGACY_PTYS is not set
diff --git a/arch/h8300/configs/edosk2674_defconfig b/arch/h8300/configs/edosk2674_defconfig
index 23791dcf6c25..7137883ff4c7 100644
--- a/arch/h8300/configs/edosk2674_defconfig
+++ b/arch/h8300/configs/edosk2674_defconfig
@@ -32,7 +32,6 @@ CONFIG_BINFMT_FLAT=y
 # CONFIG_VT is not set
 # CONFIG_UNIX98_PTYS is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/h8300/configs/h8300h-sim_defconfig b/arch/h8300/configs/h8300h-sim_defconfig
index 7fc9c2f0acc0..d4e066a1529a 100644
--- a/arch/h8300/configs/h8300h-sim_defconfig
+++ b/arch/h8300/configs/h8300h-sim_defconfig
@@ -32,7 +32,6 @@ CONFIG_BINFMT_FLAT=y
 # CONFIG_VT is not set
 # CONFIG_UNIX98_PTYS is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_EARLYCON=y
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/h8300/configs/h8s-sim_defconfig b/arch/h8300/configs/h8s-sim_defconfig
index 23791dcf6c25..7137883ff4c7 100644
--- a/arch/h8300/configs/h8s-sim_defconfig
+++ b/arch/h8300/configs/h8s-sim_defconfig
@@ -32,7 +32,6 @@ CONFIG_BINFMT_FLAT=y
 # CONFIG_VT is not set
 # CONFIG_UNIX98_PTYS is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/hexagon/configs/comet_defconfig b/arch/hexagon/configs/comet_defconfig
index f19ae2ab0aaa..c5a214716a38 100644
--- a/arch/hexagon/configs/comet_defconfig
+++ b/arch/hexagon/configs/comet_defconfig
@@ -34,7 +34,6 @@ CONFIG_NET_ETHERNET=y
 # CONFIG_SERIO is not set
 # CONFIG_CONSOLE_TRANSLATIONS is not set
 CONFIG_LEGACY_PTY_COUNT=64
-# CONFIG_DEVKMEM is not set
 # CONFIG_HW_RANDOM is not set
 CONFIG_SPI=y
 CONFIG_SPI_DEBUG=y
diff --git a/arch/m68k/configs/amcore_defconfig b/arch/m68k/configs/amcore_defconfig
index 3a84f24d41c8..6d9ed2198170 100644
--- a/arch/m68k/configs/amcore_defconfig
+++ b/arch/m68k/configs/amcore_defconfig
@@ -60,7 +60,6 @@ CONFIG_DM9000=y
 # CONFIG_VT is not set
 # CONFIG_UNIX98_PTYS is not set
 # CONFIG_DEVMEM is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_MCF=y
 CONFIG_SERIAL_MCF_BAUDRATE=115200
 CONFIG_SERIAL_MCF_CONSOLE=y
diff --git a/arch/openrisc/configs/or1ksim_defconfig b/arch/openrisc/configs/or1ksim_defconfig
index 75f2da324d0e..6e1e004047c7 100644
--- a/arch/openrisc/configs/or1ksim_defconfig
+++ b/arch/openrisc/configs/or1ksim_defconfig
@@ -43,7 +43,6 @@ CONFIG_MICREL_PHY=y
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
diff --git a/arch/sh/configs/edosk7705_defconfig b/arch/sh/configs/edosk7705_defconfig
index ef7cc31997b1..9ee35269bee2 100644
--- a/arch/sh/configs/edosk7705_defconfig
+++ b/arch/sh/configs/edosk7705_defconfig
@@ -23,7 +23,6 @@ CONFIG_SH_PCLK_FREQ=31250000
 # CONFIG_INPUT is not set
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
-# CONFIG_DEVKMEM is not set
 # CONFIG_UNIX98_PTYS is not set
 # CONFIG_LEGACY_PTYS is not set
 # CONFIG_HW_RANDOM is not set
diff --git a/arch/sh/configs/se7206_defconfig b/arch/sh/configs/se7206_defconfig
index 315b04a8dd2f..601d062250d1 100644
--- a/arch/sh/configs/se7206_defconfig
+++ b/arch/sh/configs/se7206_defconfig
@@ -71,7 +71,6 @@ CONFIG_SMC91X=y
 # CONFIG_INPUT is not set
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_NR_UARTS=4
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
diff --git a/arch/sh/configs/sh2007_defconfig b/arch/sh/configs/sh2007_defconfig
index 99975db461d8..79f02f1c0dc8 100644
--- a/arch/sh/configs/sh2007_defconfig
+++ b/arch/sh/configs/sh2007_defconfig
@@ -75,7 +75,6 @@ CONFIG_INPUT_FF_MEMLESS=y
 # CONFIG_INPUT_MOUSE is not set
 # CONFIG_SERIO is not set
 CONFIG_VT_HW_CONSOLE_BINDING=y
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
 # CONFIG_LEGACY_PTYS is not set
diff --git a/arch/sh/configs/sh7724_generic_defconfig b/arch/sh/configs/sh7724_generic_defconfig
index 2c46c0004780..cbc9389a89a8 100644
--- a/arch/sh/configs/sh7724_generic_defconfig
+++ b/arch/sh/configs/sh7724_generic_defconfig
@@ -18,7 +18,6 @@ CONFIG_CPU_IDLE=y
 # CONFIG_INPUT is not set
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_NR_UARTS=6
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
diff --git a/arch/sh/configs/sh7770_generic_defconfig b/arch/sh/configs/sh7770_generic_defconfig
index 88193153e51b..ee2357deba0f 100644
--- a/arch/sh/configs/sh7770_generic_defconfig
+++ b/arch/sh/configs/sh7770_generic_defconfig
@@ -20,7 +20,6 @@ CONFIG_CPU_IDLE=y
 # CONFIG_INPUT is not set
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_NR_UARTS=6
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
diff --git a/arch/sh/configs/sh7785lcr_32bit_defconfig b/arch/sh/configs/sh7785lcr_32bit_defconfig
index 9b885c14c400..5c725c75fcef 100644
--- a/arch/sh/configs/sh7785lcr_32bit_defconfig
+++ b/arch/sh/configs/sh7785lcr_32bit_defconfig
@@ -66,7 +66,6 @@ CONFIG_INPUT_FF_MEMLESS=m
 CONFIG_INPUT_EVDEV=y
 CONFIG_INPUT_EVBUG=m
 CONFIG_VT_HW_CONSOLE_BINDING=y
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SH_SCI=y
 CONFIG_SERIAL_SH_SCI_NR_UARTS=6
 CONFIG_SERIAL_SH_SCI_CONSOLE=y
diff --git a/arch/sparc/configs/sparc64_defconfig b/arch/sparc/configs/sparc64_defconfig
index 12a4fb0bd52a..18099099583e 100644
--- a/arch/sparc/configs/sparc64_defconfig
+++ b/arch/sparc/configs/sparc64_defconfig
@@ -122,7 +122,6 @@ CONFIG_INPUT_SPARCSPKR=y
 # CONFIG_SERIO_SERPORT is not set
 CONFIG_SERIO_PCIPS2=m
 CONFIG_SERIO_RAW=m
-# CONFIG_DEVKMEM is not set
 CONFIG_SERIAL_SUNSU=y
 CONFIG_SERIAL_SUNSU_CONSOLE=y
 CONFIG_SERIAL_SUNSAB=y
diff --git a/arch/xtensa/configs/xip_kc705_defconfig b/arch/xtensa/configs/xip_kc705_defconfig
index 4f1ff9531f6a..062148e17135 100644
--- a/arch/xtensa/configs/xip_kc705_defconfig
+++ b/arch/xtensa/configs/xip_kc705_defconfig
@@ -72,7 +72,6 @@ CONFIG_MARVELL_PHY=y
 # CONFIG_INPUT_KEYBOARD is not set
 # CONFIG_INPUT_MOUSE is not set
 # CONFIG_SERIO is not set
-CONFIG_DEVKMEM=y
 CONFIG_SERIAL_8250=y
 # CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set
 CONFIG_SERIAL_8250_CONSOLE=y
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index d229a2d0c017..b151e0fcdeb5 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -334,16 +334,6 @@ config DEVMEM
 	  memory.
 	  When in doubt, say "Y".
 
-config DEVKMEM
-	bool "/dev/kmem virtual device support"
-	# On arm64, VMALLOC_START < PAGE_OFFSET, which confuses kmem read/write
-	depends on !ARM64
-	help
-	  Say Y here if you want to support the /dev/kmem device. The
-	  /dev/kmem device is rarely used, but can be used for certain
-	  kind of kernel debugging operations.
-	  When in doubt, say "N".
-
 config NVRAM
 	tristate "/dev/nvram support"
 	depends on X86 || HAVE_ARCH_NVRAM_OPS
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 869b9f5e8e03..15dc54fa1d47 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -403,221 +403,6 @@ static int mmap_mem(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
-{
-	unsigned long pfn;
-
-	/* Turn a kernel-virtual address into a physical page frame */
-	pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
-
-	/*
-	 * RED-PEN: on some architectures there is more mapped memory than
-	 * available in mem_map which pfn_valid checks for. Perhaps should add a
-	 * new macro here.
-	 *
-	 * RED-PEN: vmalloc is not supported right now.
-	 */
-	if (!pfn_valid(pfn))
-		return -EIO;
-
-	vma->vm_pgoff = pfn;
-	return mmap_mem(file, vma);
-}
-
-/*
- * This function reads the *virtual* memory as seen by the kernel.
- */
-static ssize_t read_kmem(struct file *file, char __user *buf,
-			 size_t count, loff_t *ppos)
-{
-	unsigned long p = *ppos;
-	ssize_t low_count, read, sz;
-	char *kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
-	int err = 0;
-
-	read = 0;
-	if (p < (unsigned long) high_memory) {
-		low_count = count;
-		if (count > (unsigned long)high_memory - p)
-			low_count = (unsigned long)high_memory - p;
-
-#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
-		/* we don't have page 0 mapped on sparc and m68k.. */
-		if (p < PAGE_SIZE && low_count > 0) {
-			sz = size_inside_page(p, low_count);
-			if (clear_user(buf, sz))
-				return -EFAULT;
-			buf += sz;
-			p += sz;
-			read += sz;
-			low_count -= sz;
-			count -= sz;
-		}
-#endif
-		while (low_count > 0) {
-			sz = size_inside_page(p, low_count);
-
-			/*
-			 * On ia64 if a page has been mapped somewhere as
-			 * uncached, then it must also be accessed uncached
-			 * by the kernel or data corruption may occur
-			 */
-			kbuf = xlate_dev_kmem_ptr((void *)p);
-			if (!virt_addr_valid(kbuf))
-				return -ENXIO;
-
-			if (copy_to_user(buf, kbuf, sz))
-				return -EFAULT;
-			buf += sz;
-			p += sz;
-			read += sz;
-			low_count -= sz;
-			count -= sz;
-			if (should_stop_iteration()) {
-				count = 0;
-				break;
-			}
-		}
-	}
-
-	if (count > 0) {
-		kbuf = (char *)__get_free_page(GFP_KERNEL);
-		if (!kbuf)
-			return -ENOMEM;
-		while (count > 0) {
-			sz = size_inside_page(p, count);
-			if (!is_vmalloc_or_module_addr((void *)p)) {
-				err = -ENXIO;
-				break;
-			}
-			sz = vread(kbuf, (char *)p, sz);
-			if (!sz)
-				break;
-			if (copy_to_user(buf, kbuf, sz)) {
-				err = -EFAULT;
-				break;
-			}
-			count -= sz;
-			buf += sz;
-			read += sz;
-			p += sz;
-			if (should_stop_iteration())
-				break;
-		}
-		free_page((unsigned long)kbuf);
-	}
-	*ppos = p;
-	return read ? read : err;
-}
-
-
-static ssize_t do_write_kmem(unsigned long p, const char __user *buf,
-				size_t count, loff_t *ppos)
-{
-	ssize_t written, sz;
-	unsigned long copied;
-
-	written = 0;
-#ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
-	/* we don't have page 0 mapped on sparc and m68k.. */
-	if (p < PAGE_SIZE) {
-		sz = size_inside_page(p, count);
-		/* Hmm. Do something? */
-		buf += sz;
-		p += sz;
-		count -= sz;
-		written += sz;
-	}
-#endif
-
-	while (count > 0) {
-		void *ptr;
-
-		sz = size_inside_page(p, count);
-
-		/*
-		 * On ia64 if a page has been mapped somewhere as uncached, then
-		 * it must also be accessed uncached by the kernel or data
-		 * corruption may occur.
-		 */
-		ptr = xlate_dev_kmem_ptr((void *)p);
-		if (!virt_addr_valid(ptr))
-			return -ENXIO;
-
-		copied = copy_from_user(ptr, buf, sz);
-		if (copied) {
-			written += sz - copied;
-			if (written)
-				break;
-			return -EFAULT;
-		}
-		buf += sz;
-		p += sz;
-		count -= sz;
-		written += sz;
-		if (should_stop_iteration())
-			break;
-	}
-
-	*ppos += written;
-	return written;
-}
-
-/*
- * This function writes to the *virtual* memory as seen by the kernel.
- */
-static ssize_t write_kmem(struct file *file, const char __user *buf,
-			  size_t count, loff_t *ppos)
-{
-	unsigned long p = *ppos;
-	ssize_t wrote = 0;
-	ssize_t virtr = 0;
-	char *kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
-	int err = 0;
-
-	if (p < (unsigned long) high_memory) {
-		unsigned long to_write = min_t(unsigned long, count,
-					       (unsigned long)high_memory - p);
-		wrote = do_write_kmem(p, buf, to_write, ppos);
-		if (wrote != to_write)
-			return wrote;
-		p += wrote;
-		buf += wrote;
-		count -= wrote;
-	}
-
-	if (count > 0) {
-		kbuf = (char *)__get_free_page(GFP_KERNEL);
-		if (!kbuf)
-			return wrote ? wrote : -ENOMEM;
-		while (count > 0) {
-			unsigned long sz = size_inside_page(p, count);
-			unsigned long n;
-
-			if (!is_vmalloc_or_module_addr((void *)p)) {
-				err = -ENXIO;
-				break;
-			}
-			n = copy_from_user(kbuf, buf, sz);
-			if (n) {
-				err = -EFAULT;
-				break;
-			}
-			vwrite(kbuf, (char *)p, sz);
-			count -= sz;
-			buf += sz;
-			virtr += sz;
-			p += sz;
-			if (should_stop_iteration())
-				break;
-		}
-		free_page((unsigned long)kbuf);
-	}
-
-	*ppos = p;
-	return virtr + wrote ? : err;
-}
-
 static ssize_t read_port(struct file *file, char __user *buf,
 			 size_t count, loff_t *ppos)
 {
@@ -855,7 +640,6 @@ static int open_port(struct inode *inode, struct file *filp)
 #define write_zero	write_null
 #define write_iter_zero	write_iter_null
 #define open_mem	open_port
-#define open_kmem	open_mem
 
 static const struct file_operations __maybe_unused mem_fops = {
 	.llseek		= memory_lseek,
@@ -869,18 +653,6 @@ static const struct file_operations __maybe_unused mem_fops = {
 #endif
 };
 
-static const struct file_operations __maybe_unused kmem_fops = {
-	.llseek		= memory_lseek,
-	.read		= read_kmem,
-	.write		= write_kmem,
-	.mmap		= mmap_kmem,
-	.open		= open_kmem,
-#ifndef CONFIG_MMU
-	.get_unmapped_area = get_unmapped_area_mem,
-	.mmap_capabilities = memory_mmap_capabilities,
-#endif
-};
-
 static const struct file_operations null_fops = {
 	.llseek		= null_lseek,
 	.read		= read_null,
@@ -924,9 +696,6 @@ static const struct memdev {
 } devlist[] = {
 #ifdef CONFIG_DEVMEM
 	 [DEVMEM_MINOR] = { "mem", 0, &mem_fops, FMODE_UNSIGNED_OFFSET },
-#endif
-#ifdef CONFIG_DEVKMEM
-	 [2] = { "kmem", 0, &kmem_fops, FMODE_UNSIGNED_OFFSET },
 #endif
 	 [3] = { "null", 0666, &null_fops, 0 },
 #ifdef CONFIG_DEVPORT
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ec8f3ddf4a6a..a727186ef4cd 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -144,7 +144,7 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 /* Expect random access pattern */
 #define FMODE_RANDOM		((__force fmode_t)0x1000)
 
-/* File is huge (eg. /dev/kmem): treat loff_t as unsigned */
+/* File is huge (eg. /dev/mem): treat loff_t as unsigned */
 #define FMODE_UNSIGNED_OFFSET	((__force fmode_t)0x2000)
 
 /* File is opened with O_PATH; almost nothing can be done with it */
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index df92211cf771..390af680e916 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -198,7 +198,7 @@ static inline void set_vm_flush_reset_perms(void *addr)
 }
 #endif
 
-/* for /dev/kmem */
+/* for /proc/kcore */
 extern long vread(char *buf, char *addr, unsigned long count);
 extern long vwrite(char *buf, char *addr, unsigned long count);
 
diff --git a/kernel/configs/android-base.config b/kernel/configs/android-base.config
index d3fd428f4b92..eb701b2ac72f 100644
--- a/kernel/configs/android-base.config
+++ b/kernel/configs/android-base.config
@@ -1,5 +1,4 @@
 #  KEEP ALPHABETICALLY SORTED
-# CONFIG_DEVKMEM is not set
 # CONFIG_DEVMEM is not set
 # CONFIG_FHANDLE is not set
 # CONFIG_INET_LRO is not set
diff --git a/mm/ksm.c b/mm/ksm.c
index 9694ee2c71de..901cab89299d 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -461,7 +461,7 @@ static inline bool ksm_test_exit(struct mm_struct *mm)
  * but taking great care only to touch a ksm page, in a VM_MERGEABLE vma,
  * in case the application has unmapped and remapped mm,addr meanwhile.
  * Could a ksm page appear anywhere else?  Actually yes, in a VM_PFNMAP
- * mmap of /dev/mem or /dev/kmem, where we would not want to touch it.
+ * mmap of /dev/mem, where we would not want to touch it.
  *
  * FAULT_FLAG/FOLL_REMOTE are because we do this outside the context
  * of the process that owns 'vma'.  We also do not want to enforce
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 4f5f8c907897..ccb405b82581 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2875,7 +2875,7 @@ static int aligned_vwrite(char *buf, char *addr, unsigned long count)
  * Note: In usual ops, vread() is never necessary because the caller
  * should know vmalloc() area is valid and can use memcpy().
  * This is for routines which have to access vmalloc area without
- * any information, as /dev/kmem.
+ * any information, as /proc/kcore.
  *
  * Return: number of bytes for which addr and buf should be increased
  * (same number as @count) or %0 if [addr...addr+count) doesn't
-- 
2.29.2

[PATCH v1 2/3] mm: remove xlate_dev_kmem_ptr()

[David Hildenbrand]

Since /dev/kmem has been removed, let's remove the xlate_dev_kmem_ptr()
leftovers.

Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmerdabbelt@google.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Pierre Morel <pmorel@linux.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: linux-alpha@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-hexagon@vger.kernel.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-m68k@lists.linux-m68k.org
Cc: linux-mips@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: sparclinux@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 arch/alpha/include/asm/io.h     |  5 -----
 arch/arm/include/asm/io.h       |  5 -----
 arch/hexagon/include/asm/io.h   |  1 -
 arch/ia64/include/asm/io.h      |  1 -
 arch/ia64/include/asm/uaccess.h | 18 ------------------
 arch/m68k/include/asm/io_mm.h   |  5 -----
 arch/mips/include/asm/io.h      |  5 -----
 arch/parisc/include/asm/io.h    |  5 -----
 arch/powerpc/include/asm/io.h   |  5 -----
 arch/s390/include/asm/io.h      |  5 -----
 arch/sh/include/asm/io.h        |  5 -----
 arch/sparc/include/asm/io_64.h  |  5 -----
 include/asm-generic/io.h        | 11 -----------
 13 files changed, 76 deletions(-)

diff --git a/arch/alpha/include/asm/io.h b/arch/alpha/include/asm/io.h
index 1f6a909d1fa5..0fab5ac90775 100644
--- a/arch/alpha/include/asm/io.h
+++ b/arch/alpha/include/asm/io.h
@@ -602,11 +602,6 @@ extern void outsl (unsigned long port, const void *src, unsigned long count);
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #endif /* __KERNEL__ */
 
 #endif /* __ALPHA_IO_H */
diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index fc748122f1e0..f74944c6fe8d 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -430,11 +430,6 @@ extern void pci_iounmap(struct pci_dev *dev, void __iomem *addr);
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #include <asm-generic/io.h>
 
 #ifdef CONFIG_MMU
diff --git a/arch/hexagon/include/asm/io.h b/arch/hexagon/include/asm/io.h
index bda2a9c2df78..c33241425a5c 100644
--- a/arch/hexagon/include/asm/io.h
+++ b/arch/hexagon/include/asm/io.h
@@ -64,7 +64,6 @@ static inline void *phys_to_virt(unsigned long address)
  * convert a physical pointer to a virtual kernel pointer for
  * /dev/mem access.
  */
-#define xlate_dev_kmem_ptr(p)    __va(p)
 #define xlate_dev_mem_ptr(p)    __va(p)
 
 /*
diff --git a/arch/ia64/include/asm/io.h b/arch/ia64/include/asm/io.h
index 3d666a11a2de..6d93b923b379 100644
--- a/arch/ia64/include/asm/io.h
+++ b/arch/ia64/include/asm/io.h
@@ -277,7 +277,6 @@ extern void memset_io(volatile void __iomem *s, int c, long n);
 #define memcpy_fromio memcpy_fromio
 #define memcpy_toio memcpy_toio
 #define memset_io memset_io
-#define xlate_dev_kmem_ptr xlate_dev_kmem_ptr
 #define xlate_dev_mem_ptr xlate_dev_mem_ptr
 #include <asm-generic/io.h>
 #undef PCI_IOBASE
diff --git a/arch/ia64/include/asm/uaccess.h b/arch/ia64/include/asm/uaccess.h
index 179243c3dfc7..e19d2dcc0ced 100644
--- a/arch/ia64/include/asm/uaccess.h
+++ b/arch/ia64/include/asm/uaccess.h
@@ -272,22 +272,4 @@ xlate_dev_mem_ptr(phys_addr_t p)
 	return ptr;
 }
 
-/*
- * Convert a virtual cached kernel memory pointer to an uncached pointer
- */
-static __inline__ void *
-xlate_dev_kmem_ptr(void *p)
-{
-	struct page *page;
-	void *ptr;
-
-	page = virt_to_page((unsigned long)p);
-	if (PageUncached(page))
-		ptr = (void *)__pa(p) + __IA64_UNCACHED_OFFSET;
-	else
-		ptr = p;
-
-	return ptr;
-}
-
 #endif /* _ASM_IA64_UACCESS_H */
diff --git a/arch/m68k/include/asm/io_mm.h b/arch/m68k/include/asm/io_mm.h
index 819f611dccf2..d41fa488453b 100644
--- a/arch/m68k/include/asm/io_mm.h
+++ b/arch/m68k/include/asm/io_mm.h
@@ -397,11 +397,6 @@ static inline void isa_delay(void)
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #define readb_relaxed(addr)	readb(addr)
 #define readw_relaxed(addr)	readw(addr)
 #define readl_relaxed(addr)	readl(addr)
diff --git a/arch/mips/include/asm/io.h b/arch/mips/include/asm/io.h
index 78537aa23500..e6373e7ac892 100644
--- a/arch/mips/include/asm/io.h
+++ b/arch/mips/include/asm/io.h
@@ -552,11 +552,6 @@ extern void (*_dma_cache_inv)(unsigned long start, unsigned long size);
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 void __ioread64_copy(void *to, const void __iomem *from, size_t count);
 
 #endif /* _ASM_IO_H */
diff --git a/arch/parisc/include/asm/io.h b/arch/parisc/include/asm/io.h
index 8a11b8cf4719..0b5259102319 100644
--- a/arch/parisc/include/asm/io.h
+++ b/arch/parisc/include/asm/io.h
@@ -316,11 +316,6 @@ extern void iowrite64be(u64 val, void __iomem *addr);
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 extern int devmem_is_allowed(unsigned long pfn);
 
 #endif
diff --git a/arch/powerpc/include/asm/io.h b/arch/powerpc/include/asm/io.h
index 273edd208ec5..f130783c8301 100644
--- a/arch/powerpc/include/asm/io.h
+++ b/arch/powerpc/include/asm/io.h
@@ -662,11 +662,6 @@ static inline void name at					\
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 /*
  * We don't do relaxed operations yet, at least not with this semantic
  */
diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h
index 28664ee0abc1..e3882b012bfa 100644
--- a/arch/s390/include/asm/io.h
+++ b/arch/s390/include/asm/io.h
@@ -20,11 +20,6 @@ void *xlate_dev_mem_ptr(phys_addr_t phys);
 #define unxlate_dev_mem_ptr unxlate_dev_mem_ptr
 void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #define IO_SPACE_LIMIT 0
 
 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot);
diff --git a/arch/sh/include/asm/io.h b/arch/sh/include/asm/io.h
index 6d5c6463bc07..cf9a3ec32406 100644
--- a/arch/sh/include/asm/io.h
+++ b/arch/sh/include/asm/io.h
@@ -283,11 +283,6 @@ static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #define ARCH_HAS_VALID_PHYS_ADDR_RANGE
 int valid_phys_addr_range(phys_addr_t addr, size_t size);
 int valid_mmap_phys_addr_range(unsigned long pfn, size_t size);
diff --git a/arch/sparc/include/asm/io_64.h b/arch/sparc/include/asm/io_64.h
index 9bb27e5c22f1..ff6fe387d78c 100644
--- a/arch/sparc/include/asm/io_64.h
+++ b/arch/sparc/include/asm/io_64.h
@@ -450,11 +450,6 @@ void sbus_set_sbus64(struct device *, int);
  */
 #define xlate_dev_mem_ptr(p)	__va(p)
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#define xlate_dev_kmem_ptr(p)	p
-
 #endif
 
 #endif /* !(__SPARC64_IO_H) */
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index c6af40ce03be..33d4746b086f 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1045,17 +1045,6 @@ static inline void pci_iounmap(struct pci_dev *dev, void __iomem *p)
 #endif
 #endif /* CONFIG_GENERIC_IOMAP */
 
-/*
- * Convert a virtual cached pointer to an uncached pointer
- */
-#ifndef xlate_dev_kmem_ptr
-#define xlate_dev_kmem_ptr xlate_dev_kmem_ptr
-static inline void *xlate_dev_kmem_ptr(void *addr)
-{
-	return addr;
-}
-#endif
-
 #ifndef xlate_dev_mem_ptr
 #define xlate_dev_mem_ptr xlate_dev_mem_ptr
 static inline void *xlate_dev_mem_ptr(phys_addr_t addr)
-- 
2.29.2

[PATCH v1 3/3] mm/vmalloc: remove vwrite()

[David Hildenbrand]

The last user (/dev/kmem) is gone. Let's drop it.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: huang ying <huang.ying.caritas@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 include/linux/vmalloc.h |   1 -
 mm/nommu.c              |  10 ----
 mm/vmalloc.c            | 116 +---------------------------------------
 3 files changed, 1 insertion(+), 126 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 390af680e916..9c1b17c7dd95 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -200,7 +200,6 @@ static inline void set_vm_flush_reset_perms(void *addr)
 
 /* for /proc/kcore */
 extern long vread(char *buf, char *addr, unsigned long count);
-extern long vwrite(char *buf, char *addr, unsigned long count);
 
 /*
  *	Internals.  Dont't use..
diff --git a/mm/nommu.c b/mm/nommu.c
index 5c9ab799c0e6..85a3a68dffb6 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -210,16 +210,6 @@ long vread(char *buf, char *addr, unsigned long count)
 	return count;
 }
 
-long vwrite(char *buf, char *addr, unsigned long count)
-{
-	/* Don't allow overflow */
-	if ((unsigned long) addr + count < count)
-		count = -(unsigned long) addr;
-
-	memcpy(addr, buf, count);
-	return count;
-}
-
 /*
  *	vmalloc  -  allocate virtually contiguous memory
  *
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ccb405b82581..434f61c9c466 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2802,10 +2802,7 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
 		 * kmap() and get small overhead in this access function.
 		 */
 		if (p) {
-			/*
-			 * we can expect USER0 is not used (see vread/vwrite's
-			 * function description)
-			 */
+			/* We can expect USER0 is not used -- see vread() */
 			void *map = kmap_atomic(p);
 			memcpy(buf, map + offset, length);
 			kunmap_atomic(map);
@@ -2820,43 +2817,6 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
 	return copied;
 }
 
-static int aligned_vwrite(char *buf, char *addr, unsigned long count)
-{
-	struct page *p;
-	int copied = 0;
-
-	while (count) {
-		unsigned long offset, length;
-
-		offset = offset_in_page(addr);
-		length = PAGE_SIZE - offset;
-		if (length > count)
-			length = count;
-		p = vmalloc_to_page(addr);
-		/*
-		 * To do safe access to this _mapped_ area, we need
-		 * lock. But adding lock here means that we need to add
-		 * overhead of vmalloc()/vfree() calles for this _debug_
-		 * interface, rarely used. Instead of that, we'll use
-		 * kmap() and get small overhead in this access function.
-		 */
-		if (p) {
-			/*
-			 * we can expect USER0 is not used (see vread/vwrite's
-			 * function description)
-			 */
-			void *map = kmap_atomic(p);
-			memcpy(map + offset, buf, length);
-			kunmap_atomic(map);
-		}
-		addr += length;
-		buf += length;
-		copied += length;
-		count -= length;
-	}
-	return copied;
-}
-
 /**
  * vread() - read vmalloc area in a safe way.
  * @buf:     buffer for reading data
@@ -2936,80 +2896,6 @@ long vread(char *buf, char *addr, unsigned long count)
 	return buflen;
 }
 
-/**
- * vwrite() - write vmalloc area in a safe way.
- * @buf:      buffer for source data
- * @addr:     vm address.
- * @count:    number of bytes to be read.
- *
- * This function checks that addr is a valid vmalloc'ed area, and
- * copy data from a buffer to the given addr. If specified range of
- * [addr...addr+count) includes some valid address, data is copied from
- * proper area of @buf. If there are memory holes, no copy to hole.
- * IOREMAP area is treated as memory hole and no copy is done.
- *
- * If [addr...addr+count) doesn't includes any intersects with alive
- * vm_struct area, returns 0. @buf should be kernel's buffer.
- *
- * Note: In usual ops, vwrite() is never necessary because the caller
- * should know vmalloc() area is valid and can use memcpy().
- * This is for routines which have to access vmalloc area without
- * any information, as /dev/kmem.
- *
- * Return: number of bytes for which addr and buf should be
- * increased (same number as @count) or %0 if [addr...addr+count)
- * doesn't include any intersection with valid vmalloc area
- */
-long vwrite(char *buf, char *addr, unsigned long count)
-{
-	struct vmap_area *va;
-	struct vm_struct *vm;
-	char *vaddr;
-	unsigned long n, buflen;
-	int copied = 0;
-
-	/* Don't allow overflow */
-	if ((unsigned long) addr + count < count)
-		count = -(unsigned long) addr;
-	buflen = count;
-
-	spin_lock(&vmap_area_lock);
-	list_for_each_entry(va, &vmap_area_list, list) {
-		if (!count)
-			break;
-
-		if (!va->vm)
-			continue;
-
-		vm = va->vm;
-		vaddr = (char *) vm->addr;
-		if (addr >= vaddr + get_vm_area_size(vm))
-			continue;
-		while (addr < vaddr) {
-			if (count == 0)
-				goto finished;
-			buf++;
-			addr++;
-			count--;
-		}
-		n = vaddr + get_vm_area_size(vm) - addr;
-		if (n > count)
-			n = count;
-		if (!(vm->flags & VM_IOREMAP)) {
-			aligned_vwrite(buf, addr, n);
-			copied++;
-		}
-		buf += n;
-		addr += n;
-		count -= n;
-	}
-finished:
-	spin_unlock(&vmap_area_lock);
-	if (!copied)
-		return 0;
-	return buflen;
-}
-
 /**
  * remap_vmalloc_range_partial - map vmalloc pages to userspace
  * @vma:		vma to cover
-- 
2.29.2

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Andrew Morton]

> Let's remove /dev/kmem, which is unused and obsolete.

I grabbed these.  Silently - the cc list is amazing ;)

I was wondering if it would be better to permanently disable /dev/kmem
in Kconfig along with a comment "if you really want this thing then
email peeps@places with a very good reason why".  Let that ride for a
year or three then blam.

But this is so much more attractive, and it certainly sounds like it's
worth any damage it might cause.

We do tend to think about distros.  I bet there are a number of weird
embedded type systems using /dev/kmem - it's amazing what sorts of
hacks those people will put up with the get something out the door. 
But those systems tend to carry a lot of specialized changes anyway, so
they can just add "revert David's patch" to their pile.

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Michal Hocko]

Acked-by: Michal Hocko <mhocko@suse.com>

for the series.

Thanks!
-- 
Michal Hocko
SUSE Labs

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Balbir Singh]

On Wed, Mar 24, 2021 at 12:24:12PM -0700, Andrew Morton wrote:
> 
> > Let's remove /dev/kmem, which is unused and obsolete.
> 
> I grabbed these.  Silently - the cc list is amazing ;)
> 
> I was wondering if it would be better to permanently disable /dev/kmem
> in Kconfig along with a comment "if you really want this thing then
> email peeps@places with a very good reason why".  Let that ride for a
> year or three then blam.
> 
> But this is so much more attractive, and it certainly sounds like it's
> worth any damage it might cause.
> 
> We do tend to think about distros.  I bet there are a number of weird
> embedded type systems using /dev/kmem - it's amazing what sorts of
> hacks those people will put up with the get something out the door. 
> But those systems tend to carry a lot of specialized changes anyway, so
> they can just add "revert David's patch" to their pile.
>


I wonder if we should have the opposite of driver/staging and call it
outgoing, with a big thank you to the users and developers and also
to indicate this feature will be removed in the next (few) merge(s)
cycles. I guess not all code can be accumulated under a single
hierarchy. May not be worth the effort, just thinking out loud.

Balbir Singh 

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Greg Kroah-Hartman]

On Thu, Mar 25, 2021 at 09:58:12AM +1100, Balbir Singh wrote:
> On Wed, Mar 24, 2021 at 12:24:12PM -0700, Andrew Morton wrote:
> > 
> > > Let's remove /dev/kmem, which is unused and obsolete.
> > 
> > I grabbed these.  Silently - the cc list is amazing ;)
> > 
> > I was wondering if it would be better to permanently disable /dev/kmem
> > in Kconfig along with a comment "if you really want this thing then
> > email peeps@places with a very good reason why".  Let that ride for a
> > year or three then blam.
> > 
> > But this is so much more attractive, and it certainly sounds like it's
> > worth any damage it might cause.
> > 
> > We do tend to think about distros.  I bet there are a number of weird
> > embedded type systems using /dev/kmem - it's amazing what sorts of
> > hacks those people will put up with the get something out the door. 
> > But those systems tend to carry a lot of specialized changes anyway, so
> > they can just add "revert David's patch" to their pile.
> >
> 
> 
> I wonder if we should have the opposite of driver/staging and call it
> outgoing, with a big thank you to the users and developers and also
> to indicate this feature will be removed in the next (few) merge(s)
> cycles. I guess not all code can be accumulated under a single
> hierarchy. May not be worth the effort, just thinking out loud.

That is exactly what drivers/staging/ is being used for, for stuff on
the way out of the kernel.  wimax just left the kernel that way a week
or so ago, we've been doing this for many years now, the fact that no
one has noticed is good as that means that no one has needed the code
removed that way :)

thanks,

greg k-h

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Greg Kroah-Hartman]

On Wed, Mar 24, 2021 at 12:24:12PM -0700, Andrew Morton wrote:
> 
> > Let's remove /dev/kmem, which is unused and obsolete.
> 
> I grabbed these.  Silently - the cc list is amazing ;)

Thanks, I was going to do so, but your tree is fine with me:

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v1 0/3] drivers/char: remove /dev/kmem for good

[Enrico Weigelt, metux IT consult]

On 24.03.21 20:24, Andrew Morton wrote:

> We do tend to think about distros.  I bet there are a number of weird
> embedded type systems using /dev/kmem - it's amazing what sorts of
> hacks those people will put up with the get something out the door.

There certainly are (seen lots of such crap), another good reason for
kicking it out asap.

> But those systems tend to carry a lot of specialized changes anyway, so
> they can just add "revert David's patch" to their pile.

Often those kind of people aren't capable of that. If anyone finds such
systems, report them to cert, bsi, fd, ...


--mtx

-- 
---
Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert
werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren
GPG/PGP-Schlüssel zu.
---
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287