Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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Download tar.gz
The pistachio platform uses the U-Boot bootloader & generally boots a
kernel in the uImage format. As such it's useful to build one when
building the kernel, but to do so currently requires the user to
manually specify a uImage target on the make command line.
Make uImage.gz the pistachio platform's default build target, so that
the default is to build a kernel image that we can actually boot on a
board such as the MIPS Creator Ci40.
Marked for stable backport as far as v4.1 where pistachio support was
introduced. This is primarily useful for CI systems such as kernelci.org
which will benefit from us building a suitable image which can then be
booted as part of automated testing, extending our test coverage to the
affected stable branches.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Tested-by: Kevin Hilman <khilman@baylibre.com>
URL: https://groups.io/g/kernelci/message/388
Cc: stable@vger.kernel.org # v4.1+
Cc: linux-mips@vger.kernel.org
virt_addr_valid() really returns a boolean value, but currently uses an
integer to represent it. Switch to the bool type to make it clearer that
we really are returning a true or false value.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: linux-mips@vger.kernel.org
The virt_addr_valid() function is meant to return true iff
virt_to_page() will return a valid struct page reference. This is true
iff the address provided is found within the unmapped address range
between PAGE_OFFSET & MAP_BASE, but we don't currently check for that
condition. Instead we simply mask the address to obtain what will be a
physical address if the virtual address is indeed in the desired range,
shift it to form a PFN & then call pfn_valid(). This can incorrectly
return true if called with a virtual address which, after masking,
happens to form a physical address corresponding to a valid PFN.
For example we may vmalloc an address in the kernel mapped region
starting a MAP_BASE & obtain the virtual address:
addr = 0xc000000000002000
When masked by virt_to_phys(), which uses __pa() & in turn CPHYSADDR(),
we obtain the following (bogus) physical address:
addr = 0x2000
In a common system with PHYS_OFFSET=0 this will correspond to a valid
struct page which should really be accessed by virtual address
PAGE_OFFSET+0x2000, causing virt_addr_valid() to incorrectly return 1
indicating that the original address corresponds to a struct page.
This is equivalent to the ARM64 change made in commit ca219452c6b8
("arm64: Correctly bounds check virt_addr_valid").
This fixes fallout when hardened usercopy is enabled caused by the
related commit 517e1fbeb65f ("mm/usercopy: Drop extra
is_vmalloc_or_module() check") which removed a check for the vmalloc
range that was present from the introduction of the hardened usercopy
feature.
Signed-off-by: Paul Burton <paul.burton@mips.com>
References: ca219452c6b8 ("arm64: Correctly bounds check virt_addr_valid")
References: 517e1fbeb65f ("mm/usercopy: Drop extra is_vmalloc_or_module() check")
Reported-by: Julien Cristau <jcristau@debian.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: YunQiang Su <ysu@wavecomp.com>
URL: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=929366
Cc: stable@vger.kernel.org # v4.12+
Cc: linux-mips@vger.kernel.org
Cc: Yunqiang Su <ysu@wavecomp.com>
On rbtx4927:
BUG: Bad page state in process swapper pfn:00001
page:804b7820 refcount:0 mapcount:-128 mapping:00000000 index:0x1
flags: 0x0()
raw: 00000000 00000100 00000200 00000000 00000001 00000000 ffffff7f 00000000
page dumped because: nonzero mapcount
Modules linked in:
CPU: 0 PID: 1 Comm: swapper Not tainted 5.2.0-rc1-rbtx4927-00468-g3c05ea3d4077b756 #141
Stack : 00000000 10008400 8040dc4c 87c1b974 8044af63 8040dc4c 00000001 804a3490
00000001 81000000 0030f231 80148558 00000003 10008400 87c1dd80 3d0f9a2c
00000000 00000000 804b0000 00000000 00000007 00000000 00000081 00000000
62722d31 00000080 804b0000 39347874 00000000 804b7820 8040ce18 81000010
00000001 00000007 00000001 81000000 00000018 8021de24 00000000 804a0000
...
Call Trace:
[<8010adec>] show_stack+0x74/0x104
[<801a5e44>] bad_page+0x130/0x138
[<801a654c>] free_pcppages_bulk+0x17c/0x3b0
[<801a789c>] free_unref_page+0x40/0x68
[<801120f4>] free_init_pages+0xec/0x104
[<803bdde8>] free_initmem+0x10/0x58
[<803bdb8c>] kernel_init+0x20/0x100
[<801057c8>] ret_from_kernel_thread+0x14/0x1c
As of commit b93ddc4f9156205e ("mips: Reserve memory for the kernel
image resources"), bootmem_init() no longer reserves the memory below
the kernel, while prom_free_prom_memory() still frees it.
Fix this by reverting commit b6263ff2d6e58cc2 ("MIPS: TXx9: Implement
prom_free_prom_memory").
Suggested-by: Serge Semin <fancer.lancer@gmail.com>
Fixes: b93ddc4f9156205e ("mips: Reserve memory for the kernel image resources")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Maciej W . Rozycki <macro@linux-mips.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Commit 9cc342f6c4a0 ("treewide: prefix header search paths with
$(srctree)/") caused a build error for MIPS VDSO.
CC arch/mips/vdso/gettimeofday.o
In file included from ../arch/mips/vdso/vdso.h:26,
from ../arch/mips/vdso/gettimeofday.c:11:
../arch/mips/include/asm/page.h:12:10: fatal error: spaces.h: No such file or directory
#include <spaces.h>
^~~~~~~~~~
The cause of the error is a missing space after the compiler flag -I .
Kbuild used to have a global restriction "no space after -I", but
commit 48f6e3cf5bc6 ("kbuild: do not drop -I without parameter") got
rid of it. Having a space after -I is no longer a big deal as far as
Kbuild is concerned.
It is still a big deal for MIPS because arch/mips/vdso/Makefile
filters the header search paths, like this:
ccflags-vdso := \
$(filter -I%,$(KBUILD_CFLAGS)) \
..., which relies on the assumption that there is no space after -I .
Fixes: 9cc342f6c4a0 ("treewide: prefix header search paths with $(srctree)/")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
To meet the 'i' (immediate) constraint for the asm operands,
this function must be always inlined.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-kernel@vger.kernel.org
Pull UBIFS fixes from Richard Weinberger:
- build errors wrt xattrs
- mismerge which lead to a wrong Kconfig ifdef
- missing endianness conversion
* tag 'upstream-5.2-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
ubifs: Convert xattr inum to host order
ubifs: Use correct config name for encryption
ubifs: Fix build error without CONFIG_UBIFS_FS_XATTR
Merge yet more updates from Andrew Morton:
"A few final bits:
- large changes to vmalloc, yielding large performance benefits
- tweak the console-flush-on-panic code
- a few fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
panic: add an option to replay all the printk message in buffer
initramfs: don't free a non-existent initrd
fs/writeback.c: use rcu_barrier() to wait for inflight wb switches going into workqueue when umount
mm/compaction.c: correct zone boundary handling when isolating pages from a pageblock
mm/vmap: add DEBUG_AUGMENT_LOWEST_MATCH_CHECK macro
mm/vmap: add DEBUG_AUGMENT_PROPAGATE_CHECK macro
mm/vmalloc.c: keep track of free blocks for vmap allocation
UBIFS stores inode numbers as LE64 integers.
We have to convert them to host oder, otherwise
BE hosts won't be able to use the integer correctly.
Reported-by: kbuild test robot <lkp@intel.com>
Fixes: 9ca2d7326444 ("ubifs: Limit number of xattrs per inode")
Signed-off-by: Richard Weinberger <richard@nod.at>
Pull more Kbuild updates from Masahiro Yamada:
- remove unneeded use of cc-option, cc-disable-warning, cc-ldoption
- exclude tracked files from .gitignore
- re-enable -Wint-in-bool-context warning
- refactor samples/Makefile
- stop building immediately if syncconfig fails
- do not sprinkle error messages when $(CC) does not exist
- move arch/alpha/defconfig to the configs subdirectory
- remove crappy header search path manipulation
- add comment lines to .config to clarify the end of menu blocks
- check uniqueness of module names (adding new warnings intentionally)
* tag 'kbuild-v5.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (24 commits)
kconfig: use 'else ifneq' for Makefile to improve readability
kbuild: check uniqueness of module names
kconfig: Terminate menu blocks with a comment in the generated config
kbuild: add LICENSES to KBUILD_ALLDIRS
kbuild: remove 'addtree' and 'flags' magic for header search paths
treewide: prefix header search paths with $(srctree)/
media: prefix header search paths with $(srctree)/
media: remove unneeded header search paths
alpha: move arch/alpha/defconfig to arch/alpha/configs/defconfig
kbuild: terminate Kconfig when $(CC) or $(LD) is missing
kbuild: turn auto.conf.cmd into a mandatory include file
.gitignore: exclude .get_maintainer.ignore and .gitattributes
kbuild: add all Clang-specific flags unconditionally
kbuild: Don't try to add '-fcatch-undefined-behavior' flag
kbuild: add some extra warning flags unconditionally
kbuild: add -Wvla flag unconditionally
arch: remove dangling asm-generic wrappers
samples: guard sub-directories with CONFIG options
kbuild: re-enable int-in-bool-context warning
MAINTAINERS: kbuild: Add pattern for scripts/*vmlinux*
...
Currently on panic, kernel will lower the loglevel and print out pending
printk msg only with console_flush_on_panic().
Add an option for users to configure the "panic_print" to replay all
dmesg in buffer, some of which they may have never seen due to the
loglevel setting, which will help panic debugging .
[feng.tang@intel.com: keep the original console_flush_on_panic() inside panic()]
Link: http://lkml.kernel.org/r/1556199137-14163-1-git-send-email-feng.tang@intel.com
[feng.tang@intel.com: use logbuf lock to protect the console log index]
Link: http://lkml.kernel.org/r/1556269868-22654-1-git-send-email-feng.tang@intel.com
Link: http://lkml.kernel.org/r/1556095872-36838-1-git-send-email-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Aaro Koskinen <aaro.koskinen@nokia.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CONFIG_UBIFS_FS_ENCRYPTION is gone, fscrypt is now
controlled via CONFIG_FS_ENCRYPTION.
This problem slipped into the tree because of a mis-merge on
my side.
Reported-by: Eric Biggers <ebiggers@kernel.org>
Fixes: eea2c05d927b ("ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTION")
Signed-off-by: Richard Weinberger <richard@nod.at>