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Linux kernel
============
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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.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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Pull objtool fixes from Ingo Molnar:
"Fix a couple of endianness bugs that crept in"
* tag 'objtool-urgent-2021-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool/x86: Fix elf_add_alternative() endianness
objtool: Fix elf_create_undef_symbol() endianness
Pull irq fix from Ingo Molnar:
"Fix build warning on SH"
* tag 'irq-urgent-2021-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sh: Remove unused variable
Currently x86 kernel cross-compiled on big endian system fails at boot with:
kernel BUG at arch/x86/kernel/alternative.c:258!
Corresponding bug condition look like the following:
BUG_ON(feature >= (NCAPINTS + NBUGINTS) * 32);
Fix that by converting alternative feature/cpuid to target endianness.
Fixes: 9bc0bb50727c ("objtool/x86: Rewrite retpoline thunk calls")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-2.thread-6c9df9.git-6c9df9a8098d.your-ad-here.call-01620841104-ext-2554@work.hours
Pull x86 stack randomization fix from Ingo Molnar:
"Fix an assembly constraint that affected LLVM up to version 12"
* tag 'core-urgent-2021-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
stack: Replace "o" output with "r" input constraint
Removes this annoying warning:
arch/sh/kernel/traps.c: In function ‘nmi_trap_handler’:
arch/sh/kernel/traps.c:183:15: warning: unused variable ‘cpu’ [-Wunused-variable]
183 | unsigned int cpu = smp_processor_id();
Fixes: fe3f1d5d7cd3 ("sh: Get rid of nmi_count()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210414170517.1205430-1-eric.dumazet@gmail.com
Currently x86 cross-compilation fails on big endian system with:
x86_64-cross-ld: init/main.o: invalid string offset 488112128 >= 6229 for section `.strtab'
Mark new ELF data in elf_create_undef_symbol() as symbol, so that libelf
does endianness handling correctly.
Fixes: 2f2f7e47f052 ("objtool: Add elf_create_undef_symbol()")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: https://lore.kernel.org/r/patch-1.thread-6c9df9.git-d39264656387.your-ad-here.call-01620841104-ext-2554@work.hours
Merge misc fixes from Andrew Morton:
"13 patches.
Subsystems affected by this patch series: resource, squashfs, hfsplus,
modprobe, and mm (hugetlb, slub, userfaultfd, ksm, pagealloc, kasan,
pagemap, and ioremap)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
mm/ioremap: fix iomap_max_page_shift
docs: admin-guide: update description for kernel.modprobe sysctl
hfsplus: prevent corruption in shrinking truncate
mm/filemap: fix readahead return types
kasan: fix unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled
mm: fix struct page layout on 32-bit systems
ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()"
userfaultfd: release page in error path to avoid BUG_ON
squashfs: fix divide error in calculate_skip()
kernel/resource: fix return code check in __request_free_mem_region
mm, slub: move slub_debug static key enabling outside slab_mutex
mm/hugetlb: fix cow where page writtable in child
mm/hugetlb: fix F_SEAL_FUTURE_WRITE
"o" isn't a common asm() constraint to use; it triggers an assertion in
assert-enabled builds of LLVM that it's not recognized when targeting
aarch64 (though it appears to fall back to "m"). It's fixed in LLVM 13 now,
but there isn't really a good reason to use "o" in particular here. To
avoid causing build issues for those using assert-enabled builds of earlier
LLVM versions, the constraint needs changing.
Instead, if the point is to retain the __builtin_alloca(), make ptr appear
to "escape" via being an input to an empty inline asm block. This is
preferable anyways, since otherwise this looks like a dead store.
While the use of "r" was considered in
https://lore.kernel.org/lkml/202104011447.2E7F543@keescook/
it was only tested as an output (which looks like a dead store, and wasn't
sufficient).
Use "r" as an input constraint instead, which behaves correctly across
compilers and architectures.
Fixes: 39218ff4c625 ("stack: Optionally randomize kernel stack offset each syscall")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://reviews.llvm.org/D100412
Link: https://bugs.llvm.org/show_bug.cgi?id=49956
Link: https://lore.kernel.org/r/20210419231741.4084415-1-keescook@chromium.org
Pull btrfs fix from David Sterba:
"Handle transaction start error in btrfs_fileattr_set()
This is fix for code introduced by the new fileattr merge"
* tag 'for-5.13-rc1-part2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: handle transaction start error in btrfs_fileattr_set
Pull ARC fixes from Vineet Gupta:
- PAE fixes
- syscall num check off-by-one bug
- misc fixes
* tag 'arc-5.13-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
ARC: mm: Use max_high_pfn as a HIGHMEM zone border
ARC: mm: PAE: use 40-bit physical page mask
ARC: entry: fix off-by-one error in syscall number validation
ARC: kgdb: add 'fallthrough' to prevent a warning
arc: Fix typos/spellos
iomap_max_page_shift is expected to contain a page shift, so it can't be a
'bool', has to be an 'unsigned int'
And fix the default values: P4D_SHIFT is when huge iomap is allowed.
However, on some architectures (eg: powerpc book3s/64), P4D_SHIFT is not a
constant so it can't be used to initialise a static variable. So,
initialise iomap_max_page_shift with a maximum shift supported by the
architecture, it is gated by P4D_SHIFT in vmap_try_huge_p4d() anyway.
Link: https://lkml.kernel.org/r/ad2d366015794a9f21320dcbdd0a8eb98979e9df.1620898113.git.christophe.leroy@csgroup.eu
Fixes: bbc180a5adb0 ("mm: HUGE_VMAP arch support cleanup")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit b9d79e4ca4ff ("fbmem: Mark proc_fb_seq_ops as __maybe_unused")
places the '__maybe_unused' in an entirely incorrect location between
the "struct" keyword and the structure name.
It's a wonder that gcc accepts that silently, but clang quite reasonably
warns about it:
drivers/video/fbdev/core/fbmem.c:736:21: warning: attribute declaration must precede definition [-Wignored-attributes]
static const struct __maybe_unused seq_operations proc_fb_seq_ops = {
^
Fix it.
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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