drivers/char: remove /dev/kmem for good
authorDavid Hildenbrand <david@redhat.com>
Fri, 7 May 2021 01:05:55 +0000 (18:05 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 7 May 2021 07:26:34 +0000 (00:26 -0700)
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 <david@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.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: 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: 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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
25 files changed:
Documentation/admin-guide/devices.txt
arch/arm/configs/dove_defconfig
arch/arm/configs/magician_defconfig
arch/arm/configs/moxart_defconfig
arch/arm/configs/mps2_defconfig
arch/arm/configs/mvebu_v5_defconfig
arch/arm/configs/xcep_defconfig
arch/hexagon/configs/comet_defconfig
arch/m68k/configs/amcore_defconfig
arch/openrisc/configs/or1ksim_defconfig
arch/sh/configs/edosk7705_defconfig
arch/sh/configs/se7206_defconfig
arch/sh/configs/sh2007_defconfig
arch/sh/configs/sh7724_generic_defconfig
arch/sh/configs/sh7770_generic_defconfig
arch/sh/configs/sh7785lcr_32bit_defconfig
arch/sparc/configs/sparc64_defconfig
arch/xtensa/configs/xip_kc705_defconfig
drivers/char/Kconfig
drivers/char/mem.c
include/linux/fs.h
include/linux/vmalloc.h
kernel/configs/android-base.config
mm/ksm.c
mm/vmalloc.c

index ef41f77cb9799b1b9808068622db57062ac4095f..9c2be821c22547e13dc17f26cfa93ce5bfaa0e15 100644 (file)
@@ -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
index e70c997d5f4ccb0f85bbd10f4f412c3f7f6d3167..b935162a8bbaf2310cbeb7402a52f514e90b4b96 100644 (file)
@@ -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
index b4670d42f378c6921fad8ae6670a388d593c4c53..abde1fb23b207e57f5d62ceecb709794e3692af8 100644 (file)
@@ -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
index 6834e97af34861b4df3ab8c12dd7ace7b0d4efc2..eacc089d86c5637bda79aecaa236c5fd83e37fc5 100644 (file)
@@ -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
index 1d923dbb9928f37a164c356f7d019a4ece4b3fee..89f4a6ff30bd1c530f300ccad4e27f558acac0e2 100644 (file)
@@ -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
index 4f16716bfc322b88762d8877aef285c530e70e21..d57ff30dabff177416770c80ff6df9670818b24b 100644 (file)
@@ -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
index f1fbdfc5c8c62f03a033402249fb17501441d120..4d8e7f2eaef79e246ac5582d902758485413d726 100644 (file)
@@ -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
index f19ae2ab0aaa0f6e4613ffa27d38c58d7bfbd845..c5a214716a385b75444b395c795fdcf6ec40c6a3 100644 (file)
@@ -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
index 3a84f24d41c84e47bca0c3c1104c37186c9b49ff..6d9ed2198170a984ea0679f173c10c0951568025 100644 (file)
@@ -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
index 75f2da324d0e70284663040d381ed013acfb27d5..6e1e004047c75f1baee35dfd1af1777d51b0189a 100644 (file)
@@ -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
index ef7cc31997b16eb5c6ad440494e2365e61cd3082..9ee35269bee260b07693e3c3a0680173f7ce3929 100644 (file)
@@ -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
index 315b04a8dd2fb3b5e63b92114646c8f4d87a5963..601d062250d11cbebdc10e2f93efc241e890306a 100644 (file)
@@ -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
index 99975db461d8251d5c6ea5d7c47a47c6607883ca..79f02f1c0dc83031006c7a1fd630167415e0b9dd 100644 (file)
@@ -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
index 2c46c0004780337a7b2f8bb19ebd315769b5bbcd..cbc9389a89a8c0ae59b68d568949ab4cf29c1739 100644 (file)
@@ -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
index 88193153e51bfd809c57e44863bf4dabdf82a0a4..ee2357deba0f1ca7ae62362b1a54472f4e852c1a 100644 (file)
@@ -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
index 9b885c14c4003bba9e5e684d836ddba399a48ad8..5c725c75fcef723c4081f1257d3a4f15e6f4f6cb 100644 (file)
@@ -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
index 12a4fb0bd52aa41d2865e49450b7c4b6ad4b1656..18099099583ed9aa2fde66d29835eab9ab73831d 100644 (file)
@@ -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
index 4f1ff9531f6a10e67b01db9a30c7d0d7f2932274..062148e1713513ba167f31cfb7268039dcf5a1c1 100644 (file)
@@ -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
index d229a2d0c017493a858636ed947ba1f953dfad78..b151e0fcdeb5fcdf0f3439797007d4a7070e42ee 100644 (file)
@@ -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
index 869b9f5e8e0315d4e497fcfec20a0e48c7414f85..15dc54fa1d472ad87051233210882729c0829729 100644 (file)
@@ -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
index acef282b97c68f4276be2d5d0547653be16c02ed..c3c88fdb9b2a55a260dbe753fbf932ad7099c218 100644 (file)
@@ -145,7 +145,7 @@ 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 */
index 394d03cc0e926619b8b0ba8b1fa808bfdee637ee..f31ba59fb1ef65aea1a0df86168481438b2b2085 100644 (file)
@@ -227,7 +227,7 @@ 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);
 
index d3fd428f4b92606915c959467eed22e39ed0b9af..eb701b2ac72ffef8573781f4c77ae7e4f9cea938 100644 (file)
@@ -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
index b321a67ebaa965b96aa012041140e8802773ce06..b7cbcc7d49777dcafd37a13474b9ad4c19c5634a 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -459,7 +459,7 @@ 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
index 9c539f0730a510738cebabb878e6ab4ca5083241..2868692c6807271e5e3b79612fe17e777ff936c1 100644 (file)
@@ -3219,7 +3219,7 @@ 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