arch/sh/boards/mach-kfr2r09/setup.c does not need to #include
<mtd/onenand.h>, and doing so causes a build warning, so drop that header
file.

In file included from ../arch/sh/boards/mach-kfr2r09/setup.c:28:
../include/linux/mtd/onenand.h:225:12: warning: 'struct mtd_oob_ops' declared inside parameter list will not be visible outside of this definition or declaration
     struct mtd_oob_ops *ops);

Link: http://lkml.kernel.org/r/702f0a25-c63e-6912-4640-6ab0f00afbc7@infradead.org
Fixes: f3590dc3 ("media: arch: sh: kfr2r09: Use new renesas-ceu camera driver")
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Reported-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Suggested-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: NMiquel Raynal <miquel.raynal@bootlin.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>
Cc: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

New declarations and identifier (__always_inline).

Link: http://lkml.kernel.org/r/154505048571.504.18330420599768007443.stgit@localhost.localdomainSigned-off-by: NKirill Tkhai <ktkhai@virtuozzo.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Constantine Shulyupin <const@MakeLinux.com>
Cc: Kirill Tkhai <ktkhai@virtuozzo.com>
Cc: Joey Pabalinas <joeypabalinas@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a script that will run spdxcheck.py through a couple of self tests to
simplify validation in the future.  The tests are run for both Python 2
and Python 3 to make sure all changes to the script remain compatible
across both versions.

The script tests a regular text file (Makefile) for basic sanity checks
and then runs it on a binary file (Documentation/logo.gif) to make sure it
works in both cases.  It also tests opening files passed on the command
line as well as piped files read from standard input.  Finally a run on
the complete tree will be performed to catch any other potential issues.

Link: http://lkml.kernel.org/r/20181212131210.28024-2-thierry.reding@gmail.comSigned-off-by: NThierry Reding <treding@nvidia.com>
Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Joe Perches <joe@perches.com>
Cc: Jeremy Cline <jcline@redhat.com>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is to track dynamic amount of stack growth for aarch64, so it is
possible to print out offensive functions that may consume too much stack.
For example,

0xffff2000084d1270 try_to_unmap_one [vmlinux]:		Dynamic (0xcf0)
0xffff200008538358 migrate_page_move_mapping [vmlinux]:	Dynamic (0xc60)
0xffff2000081276c8 copy_process.isra.2 [vmlinux]:	Dynamic (0xb20)
0xffff200008424958 show_free_areas [vmlinux]:		Dynamic (0xb40)
0xffff200008545178 __split_huge_pmd_locked [vmlinux]:	Dynamic (0xb30)
0xffff200008555120 collapse_shmem [vmlinux]:		Dynamic (0xbc0)
0xffff20000862e0d0 do_direct_IO [vmlinux]:		Dynamic (0xb70)
0xffff200008cc0aa0 md_do_sync [vmlinux]:		Dynamic (0xb90)

Link: http://lkml.kernel.org/r/20181208025143.39363-1-cai@lca.pwSigned-off-by: NQian Cai <cai@lca.pw>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Running something like:

	decodecode vmlinux .

leads to interested results where not only the leading "." gets stripped
from the displayed paths, but also anywhere in the string, displaying
something like:

	kvm_vcpu_check_block (arch/arm64/kvm/virt/kvm/kvm_mainc:2141)

which doesn't help further processing.

Fix it by only stripping the base path if it is a prefix of the path.

Link: http://lkml.kernel.org/r/20181210174659.31054-3-marc.zyngier@arm.comSigned-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When running decodecode natively on arm64, ARCH is likely not to be set,
and we end-up with .4byte instead of .inst when generating the
disassembly.

Similar effects would occur if running natively on a 32bit ARM platform,
although that's even less popular.

A simple workaround is to populate ARCH when it is not set and that we're
running on an arm/arm64 system.

Link: http://lkml.kernel.org/r/20181210174659.31054-2-marc.zyngier@arm.comSigned-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since __LINE__ is part of the symbol created by __ADDRESSABLE, almost
any change causes those symbols to disappear and get reincarnated, e.g.

add/remove: 4/4 grow/shrink: 0/3 up/down: 32/-171 (-139)
Function                                     old     new   delta
__addressable_tracing_set_default_clock8649       -       8      +8
__addressable_tracer_init_tracefs8631          -       8      +8
__addressable_ftrace_dump8383                  -       8      +8
__addressable_clear_boot_tracer8632            -       8      +8
__addressable_tracing_set_default_clock8650       8       -      -8
__addressable_tracer_init_tracefs8632          8       -      -8
__addressable_ftrace_dump8384                  8       -      -8
__addressable_clear_boot_tracer8633            8       -      -8
trace_default_header                         663     642     -21
tracing_mark_raw_write                       406     355     -51
tracing_mark_write                           624     557     -67
Total: Before=63889, After=63750, chg -0.22%

They're small and in .discard, so ignore them, leading to more useful

add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-139 (-139)
Function                                     old     new   delta
trace_default_header                         663     642     -21
tracing_mark_raw_write                       406     355     -51
tracing_mark_write                           624     557     -67
Total: Before=63721, After=63582, chg -0.22%

Link: http://lkml.kernel.org/r/20181102210030.8383-1-linux@rasmusvillemoes.dkSigned-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: Maninder Singh <maninder1.s@samsung.com>
Cc: Matteo Croce <mcroce@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds a "SPDX-License-Identifier: GPL-2.0" mark to all source
files under mm/kasan.

Link: http://lkml.kernel.org/r/bce2d1e618afa5142e81961ab8fa4b4165337380.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch updates KASAN documentation to reflect the addition of the new
tag-based mode.

Link: http://lkml.kernel.org/r/aabef9de317c54b8a3919a4946ce534c6576726a.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now, that all the necessary infrastructure code has been introduced,
select HAVE_ARCH_KASAN_SW_TAGS for arm64 to enable software tag-based
KASAN mode.

Link: http://lkml.kernel.org/r/25abce9a21d0c1df2d9d72488aced418c3465d7b.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds __must_check annotations to kasan hooks that return a
pointer to make sure that a tagged pointer always gets propagated.

Link: http://lkml.kernel.org/r/03b269c5e453945f724bfca3159d4e1333a8fb1c.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Suggested-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tag-based KASAN doesn't check memory accesses through pointers tagged with
0xff.  When page_address is used to get pointer to memory that corresponds
to some page, the tag of the resulting pointer gets set to 0xff, even
though the allocated memory might have been tagged differently.

For slab pages it's impossible to recover the correct tag to return from
page_address, since the page might contain multiple slab objects tagged
with different values, and we can't know in advance which one of them is
going to get accessed.  For non slab pages however, we can recover the tag
in page_address, since the whole page was marked with the same tag.

This patch adds tagging to non slab memory allocated with pagealloc.  To
set the tag of the pointer returned from page_address, the tag gets stored
to page->flags when the memory gets allocated.

Link: http://lkml.kernel.org/r/d758ddcef46a5abc9970182b9137e2fbee202a2c.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tag-based KASAN inline instrumentation mode (which embeds checks of shadow
memory into the generated code, instead of inserting a callback) generates
a brk instruction when a tag mismatch is detected.

This commit adds a tag-based KASAN specific brk handler, that decodes the
immediate value passed to the brk instructions (to extract information
about the memory access that triggered the mismatch), reads the register
values (x0 contains the guilty address) and reports the bug.

Link: http://lkml.kernel.org/r/c91fe7684070e34dc34b419e6b69498f4dcacc2d.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This commit adds tag-based KASAN specific hooks implementation and
adjusts common generic and tag-based KASAN ones.

1. When a new slab cache is created, tag-based KASAN rounds up the size of
   the objects in this cache to KASAN_SHADOW_SCALE_SIZE (== 16).

2. On each kmalloc tag-based KASAN generates a random tag, sets the shadow
   memory, that corresponds to this object to this tag, and embeds this
   tag value into the top byte of the returned pointer.

3. On each kfree tag-based KASAN poisons the shadow memory with a random
   tag to allow detection of use-after-free bugs.

The rest of the logic of the hook implementation is very much similar to
the one provided by generic KASAN. Tag-based KASAN saves allocation and
free stack metadata to the slab object the same way generic KASAN does.

Link: http://lkml.kernel.org/r/bda78069e3b8422039794050ddcb2d53d053ed41.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While with SLUB we can actually preassign tags for caches with contructors
and store them in pointers in the freelist, SLAB doesn't allow that since
the freelist is stored as an array of indexes, so there are no pointers to
store the tags.

Instead we compute the tag twice, once when a slab is created before
calling the constructor and then again each time when an object is
allocated with kmalloc.  Tag is computed simply by taking the lowest byte
of the index that corresponds to the object.  However in kasan_kmalloc we
only have access to the objects pointer, so we need a way to find out
which index this object corresponds to.

This patch moves obj_to_index from slab.c to include/linux/slab_def.h to
be reused by KASAN.

Link: http://lkml.kernel.org/r/c02cd9e574cfd93858e43ac94b05e38f891fef64.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This commit adds rountines, that print tag-based KASAN error reports.
Those are quite similar to generic KASAN, the difference is:

1. The way tag-based KASAN finds the first bad shadow cell (with a
   mismatching tag). Tag-based KASAN compares memory tags from the shadow
   memory to the pointer tag.

2. Tag-based KASAN reports all bugs with the "KASAN: invalid-access"
   header.

Also simplify generic KASAN find_first_bad_addr.

Link: http://lkml.kernel.org/r/aee6897b1bd077732a315fd84c6b4f234dbfdfcb.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move generic KASAN specific error reporting routines to generic_report.c
without any functional changes, leaving common error reporting code in
report.c to be later reused by tag-based KASAN.

Link: http://lkml.kernel.org/r/ba48c32f8e5aefedee78998ccff0413bee9e0f5b.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The krealloc function checks where the same buffer was reused or a new one
allocated by comparing kernel pointers.  Tag-based KASAN changes memory
tag on the krealloc'ed chunk of memory and therefore also changes the
pointer tag of the returned pointer.  Therefore we need to perform
comparison on untagged (with tags reset) pointers to check whether it's
the same memory region or not.

Link: http://lkml.kernel.org/r/14f6190d7846186a3506cd66d82446646fe65090.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tag-based KASAN uses the Top Byte Ignore feature of arm64 CPUs to store a
pointer tag in the top byte of each pointer.  This commit enables the
TCR_TBI1 bit, which enables Top Byte Ignore for the kernel, when tag-based
KASAN is used.

Link: http://lkml.kernel.org/r/f51eca084c8cdb2f3a55195fe342dc8953b7aead.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Right now arm64 fault handling code removes pointer tags from addresses
covered by TTBR0 in faults taken from both EL0 and EL1, but doesn't do
that for pointers covered by TTBR1.

This patch adds two helper functions is_ttbr0_addr() and is_ttbr1_addr(),
where the latter one accounts for the fact that TTBR1 pointers might be
tagged when tag-based KASAN is in use, and uses these helper functions to
perform pointer checks in arch/arm64/mm/fault.c.

Link: http://lkml.kernel.org/r/3f349b0e9e48b5df3298a6b4ae0634332274494a.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Suggested-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

An object constructor can initialize pointers within this objects based on
the address of the object.  Since the object address might be tagged, we
need to assign a tag before calling constructor.

The implemented approach is to assign tags to objects with constructors
when a slab is allocated and call constructors once as usual.  The
downside is that such object would always have the same tag when it is
reallocated, so we won't catch use-after-frees on it.

Also pressign tags for objects from SLAB_TYPESAFE_BY_RCU caches, since
they can be validy accessed after having been freed.

Link: http://lkml.kernel.org/r/f158a8a74a031d66f0a9398a5b0ed453c37ba09a.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

virt_addr_is_linear (which is used by virt_addr_valid) assumes that the
top byte of the address is 0xff, which isn't always the case with
tag-based KASAN.

This patch resets the tag in this macro.

Link: http://lkml.kernel.org/r/df73a37dd5ed37f4deaf77bc718e9f2e590e69b1.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This commit adds a few helper functions, that are meant to be used to work
with tags embedded in the top byte of kernel pointers: to set, to get or
to reset the top byte.

Link: http://lkml.kernel.org/r/f6c6437bb8e143bc44f42c3c259c62e734be7935.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the untagged_addr() macro from arch/arm64/include/asm/uaccess.h
to arch/arm64/include/asm/memory.h to be later reused by KASAN.

Also make the untagged_addr() macro accept all kinds of address types
(void *, unsigned long, etc.). This allows not to specify type casts in
each place where the macro is used. This is done by using __typeof__.

Link: http://lkml.kernel.org/r/2e9ef8d2ed594106eca514b268365b5419113f6a.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

A tag-based KASAN shadow memory cell contains a memory tag, that
corresponds to the tag in the top byte of the pointer, that points to that
memory.  The native top byte value of kernel pointers is 0xff, so with
tag-based KASAN we need to initialize shadow memory to 0xff.

[cai@lca.pw: arm64: skip kmemleak for KASAN again\
  Link: http://lkml.kernel.org/r/20181226020550.63712-1-cai@lca.pw
Link: http://lkml.kernel.org/r/5cc1b789aad7c99cf4f3ec5b328b147ad53edb40.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With tag based KASAN mode the early shadow value is 0xff and not 0x00, so
this patch renames kasan_zero_(page|pte|pmd|pud|p4d) to
kasan_early_shadow_(page|pte|pmd|pud|p4d) to avoid confusion.

Link: http://lkml.kernel.org/r/3fed313280ebf4f88645f5b89ccbc066d320e177.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Suggested-by: NMark Rutland <mark.rutland@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tag-based KASAN uses 1 shadow byte for 16 bytes of kernel memory, so it
requires 1/16th of the kernel virtual address space for the shadow memory.

This commit sets KASAN_SHADOW_SCALE_SHIFT to 4 when the tag-based KASAN
mode is enabled.

Link: http://lkml.kernel.org/r/308b6bd49f756bb5e533be93c6f085ba99b30339.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Acked-by: NWill Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This commit splits the current CONFIG_KASAN config option into two:
1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one
   that exists now);
2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode.

The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have
another hardware tag-based KASAN mode, that will rely on hardware memory
tagging support in arm64.

With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to
instrument kernel files with -fsantize=kernel-hwaddress (except the ones
for which KASAN_SANITIZE := n is set).

Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both
CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes.

This commit also adds empty placeholder (for now) implementation of
tag-based KASAN specific hooks inserted by the compiler and adjusts
common hooks implementation.

While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option
is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will
enable once all the infrastracture code has been added.

Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We now have two KASAN modes: generic KASAN and tag-based KASAN.  Rename
kasan.c to generic.c to reflect that.  Also rename kasan_init.c to init.c
as it contains initialization code for both KASAN modes.

Link: http://lkml.kernel.org/r/88c6fd2a883e459e6242030497230e5fb0d44d44.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Tag-based KASAN reuses a significant part of the generic KASAN code, so
move the common parts to common.c without any functional changes.

Link: http://lkml.kernel.org/r/114064d002356e03bb8cc91f7835e20dc61b51d9.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The previous patch updated KASAN hooks signatures and their usage in SLAB
and SLUB code, except for the early_kmem_cache_node_alloc function.  This
patch handles that function separately, as it requires to reorder some of
the initialization code to correctly propagate a tagged pointer in case a
tag is assigned by kasan_kmalloc.

Link: http://lkml.kernel.org/r/fc8d0fdcf733a7a52e8d0daaa650f4736a57de8c.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "kasan: add software tag-based mode for arm64", v13.

This patchset adds a new software tag-based mode to KASAN [1].  (Initially
this mode was called KHWASAN, but it got renamed, see the naming rationale
at the end of this section).

The plan is to implement HWASan [2] for the kernel with the incentive,
that it's going to have comparable to KASAN performance, but in the same
time consume much less memory, trading that off for somewhat imprecise bug
detection and being supported only for arm64.

The underlying ideas of the approach used by software tag-based KASAN are:

1. By using the Top Byte Ignore (TBI) arm64 CPU feature, we can store
   pointer tags in the top byte of each kernel pointer.

2. Using shadow memory, we can store memory tags for each chunk of kernel
   memory.

3. On each memory allocation, we can generate a random tag, embed it into
   the returned pointer and set the memory tags that correspond to this
   chunk of memory to the same value.

4. By using compiler instrumentation, before each memory access we can add
   a check that the pointer tag matches the tag of the memory that is being
   accessed.

5. On a tag mismatch we report an error.

With this patchset the existing KASAN mode gets renamed to generic KASAN,
with the word "generic" meaning that the implementation can be supported
by any architecture as it is purely software.

The new mode this patchset adds is called software tag-based KASAN.  The
word "tag-based" refers to the fact that this mode uses tags embedded into
the top byte of kernel pointers and the TBI arm64 CPU feature that allows
to dereference such pointers.  The word "software" here means that shadow
memory manipulation and tag checking on pointer dereference is done in
software.  As it is the only tag-based implementation right now, "software
tag-based" KASAN is sometimes referred to as simply "tag-based" in this
patchset.

A potential expansion of this mode is a hardware tag-based mode, which
would use hardware memory tagging support (announced by Arm [3]) instead
of compiler instrumentation and manual shadow memory manipulation.

Same as generic KASAN, software tag-based KASAN is strictly a debugging
feature.

[1] https://www.kernel.org/doc/html/latest/dev-tools/kasan.html

[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html

[3] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architecture-2018-developments-armv85a

====== Rationale

On mobile devices generic KASAN's memory usage is significant problem.
One of the main reasons to have tag-based KASAN is to be able to perform a
similar set of checks as the generic one does, but with lower memory
requirements.

Comment from Vishwath Mohan <vishwath@google.com>:

I don't have data on-hand, but anecdotally both ASAN and KASAN have proven
problematic to enable for environments that don't tolerate the increased
memory pressure well.  This includes

(a) Low-memory form factors - Wear, TV, Things, lower-tier phones like Go,
(c) Connected components like Pixel's visual core [1].

These are both places I'd love to have a low(er) memory footprint option at
my disposal.

Comment from Evgenii Stepanov <eugenis@google.com>:

Looking at a live Android device under load, slab (according to
/proc/meminfo) + kernel stack take 8-10% available RAM (~350MB).  KASAN's
overhead of 2x - 3x on top of it is not insignificant.

Not having this overhead enables near-production use - ex.  running
KASAN/KHWASAN kernel on a personal, daily-use device to catch bugs that do
not reproduce in test configuration.  These are the ones that often cost
the most engineering time to track down.

CPU overhead is bad, but generally tolerable.  RAM is critical, in our
experience.  Once it gets low enough, OOM-killer makes your life
miserable.

[1] https://www.blog.google/products/pixel/pixel-visual-core-image-processing-and-machine-learning-pixel-2/

====== Technical details

Software tag-based KASAN mode is implemented in a very similar way to the
generic one. This patchset essentially does the following:

1. TCR_TBI1 is set to enable Top Byte Ignore.

2. Shadow memory is used (with a different scale, 1:16, so each shadow
   byte corresponds to 16 bytes of kernel memory) to store memory tags.

3. All slab objects are aligned to shadow scale, which is 16 bytes.

4. All pointers returned from the slab allocator are tagged with a random
   tag and the corresponding shadow memory is poisoned with the same value.

5. Compiler instrumentation is used to insert tag checks. Either by
   calling callbacks or by inlining them (CONFIG_KASAN_OUTLINE and
   CONFIG_KASAN_INLINE flags are reused).

6. When a tag mismatch is detected in callback instrumentation mode
   KASAN simply prints a bug report. In case of inline instrumentation,
   clang inserts a brk instruction, and KASAN has it's own brk handler,
   which reports the bug.

7. The memory in between slab objects is marked with a reserved tag, and
   acts as a redzone.

8. When a slab object is freed it's marked with a reserved tag.

Bug detection is imprecise for two reasons:

1. We won't catch some small out-of-bounds accesses, that fall into the
   same shadow cell, as the last byte of a slab object.

2. We only have 1 byte to store tags, which means we have a 1/256
   probability of a tag match for an incorrect access (actually even
   slightly less due to reserved tag values).

Despite that there's a particular type of bugs that tag-based KASAN can
detect compared to generic KASAN: use-after-free after the object has been
allocated by someone else.

====== Testing

Some kernel developers voiced a concern that changing the top byte of
kernel pointers may lead to subtle bugs that are difficult to discover.
To address this concern deliberate testing has been performed.

It doesn't seem feasible to do some kind of static checking to find
potential issues with pointer tagging, so a dynamic approach was taken.
All pointer comparisons/subtractions have been instrumented in an LLVM
compiler pass and a kernel module that would print a bug report whenever
two pointers with different tags are being compared/subtracted (ignoring
comparisons with NULL pointers and with pointers obtained by casting an
error code to a pointer type) has been used.  Then the kernel has been
booted in QEMU and on an Odroid C2 board and syzkaller has been run.

This yielded the following results.

The two places that look interesting are:

is_vmalloc_addr in include/linux/mm.h
is_kernel_rodata in mm/util.c

Here we compare a pointer with some fixed untagged values to make sure
that the pointer lies in a particular part of the kernel address space.
Since tag-based KASAN doesn't add tags to pointers that belong to rodata
or vmalloc regions, this should work as is.  To make sure debug checks to
those two functions that check that the result doesn't change whether we
operate on pointers with or without untagging has been added.

A few other cases that don't look that interesting:

Comparing pointers to achieve unique sorting order of pointee objects
(e.g. sorting locks addresses before performing a double lock):

tty_ldisc_lock_pair_timeout in drivers/tty/tty_ldisc.c
pipe_double_lock in fs/pipe.c
unix_state_double_lock in net/unix/af_unix.c
lock_two_nondirectories in fs/inode.c
mutex_lock_double in kernel/events/core.c

ep_cmp_ffd in fs/eventpoll.c
fsnotify_compare_groups fs/notify/mark.c

Nothing needs to be done here, since the tags embedded into pointers
don't change, so the sorting order would still be unique.

Checks that a pointer belongs to some particular allocation:

is_sibling_entry in lib/radix-tree.c
object_is_on_stack in include/linux/sched/task_stack.h

Nothing needs to be done here either, since two pointers can only belong
to the same allocation if they have the same tag.

Overall, since the kernel boots and works, there are no critical bugs.
As for the rest, the traditional kernel testing way (use until fails) is
the only one that looks feasible.

Another point here is that tag-based KASAN is available under a separate
config option that needs to be deliberately enabled. Even though it might
be used in a "near-production" environment to find bugs that are not found
during fuzzing or running tests, it is still a debug tool.

====== Benchmarks

The following numbers were collected on Odroid C2 board. Both generic and
tag-based KASAN were used in inline instrumentation mode.

Boot time [1]:
* ~1.7 sec for clean kernel
* ~5.0 sec for generic KASAN
* ~5.0 sec for tag-based KASAN

Network performance [2]:
* 8.33 Gbits/sec for clean kernel
* 3.17 Gbits/sec for generic KASAN
* 2.85 Gbits/sec for tag-based KASAN

Slab memory usage after boot [3]:
* ~40 kb for clean kernel
* ~105 kb (~260% overhead) for generic KASAN
* ~47 kb (~20% overhead) for tag-based KASAN

KASAN memory overhead consists of three main parts:
1. Increased slab memory usage due to redzones.
2. Shadow memory (the whole reserved once during boot).
3. Quaratine (grows gradually until some preset limit; the more the limit,
   the more the chance to detect a use-after-free).

Comparing tag-based vs generic KASAN for each of these points:
1. 20% vs 260% overhead.
2. 1/16th vs 1/8th of physical memory.
3. Tag-based KASAN doesn't require quarantine.

[1] Time before the ext4 driver is initialized.
[2] Measured as `iperf -s & iperf -c 127.0.0.1 -t 30`.
[3] Measured as `cat /proc/meminfo | grep Slab`.

====== Some notes

A few notes:

1. The patchset can be found here:
   https://github.com/xairy/kasan-prototype/tree/khwasan

2. Building requires a recent Clang version (7.0.0 or later).

3. Stack instrumentation is not supported yet and will be added later.

This patch (of 25):

Tag-based KASAN changes the value of the top byte of pointers returned
from the kernel allocation functions (such as kmalloc).  This patch
updates KASAN hooks signatures and their usage in SLAB and SLUB code to
reflect that.

Link: http://lkml.kernel.org/r/aec2b5e3973781ff8a6bb6760f8543643202c451.1544099024.git.andreyknvl@google.comSigned-off-by: NAndrey Konovalov <andreyknvl@google.com>
Reviewed-by: NAndrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: NDmitry Vyukov <dvyukov@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull file locking updates from Jeff Layton:
 "The main change in this set is Neil Brown's work to reduce the
  thundering herd problem when a heavily-contended file lock is
  released.

  Previously we'd always wake up all waiters when this occurred. With
  this set, we'll now we only wake up waiters that were blocked on the
  range being released"

* tag 'locks-v4.21-1' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  locks: Use inode_is_open_for_write
  fs/locks: remove unnecessary white space.
  fs/locks: merge posix_unblock_lock() and locks_delete_block()
  fs/locks: create a tree of dependent requests.
  fs/locks: change all *_conflict() functions to return bool.
  fs/locks: always delete_block after waiting.
  fs/locks: allow a lock request to block other requests.
  fs/locks: use properly initialized file_lock when unlocking.
  ocfs2: properly initial file_lock used for unlock.
  gfs2: properly initial file_lock used for unlock.
  NFS: use locks_copy_lock() to copy locks.
  fs/locks: split out __locks_wake_up_blocks().
  fs/locks: rename some lists and pointers.

Pull ext4 updates from Ted Ts'o:
 "All cleanups and bug fixes; most notably, fix some problems discovered
  in ext4's NFS support, and fix an ioctl (EXT4_IOC_GROUP_ADD) used by
  old versions of e2fsprogs which we accidentally broke a while back.

  Also fixed some error paths in ext4's quota and inline data support.

  Finally, improve tail latency in jbd2's commit code"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: check for shutdown and r/o file system in ext4_write_inode()
  ext4: force inode writes when nfsd calls commit_metadata()
  ext4: avoid declaring fs inconsistent due to invalid file handles
  ext4: include terminating u32 in size of xattr entries when expanding inodes
  ext4: compare old and new mode before setting update_mode flag
  ext4: fix EXT4_IOC_GROUP_ADD ioctl
  ext4: hard fail dax mount on unsupported devices
  jbd2: update locking documentation for transaction_t
  ext4: remove redundant condition check
  jbd2: clean up indentation issue, replace spaces with tab
  ext4: clean up indentation issues, remove extraneous tabs
  ext4: missing unlock/put_page() in ext4_try_to_write_inline_data()
  ext4: fix possible use after free in ext4_quota_enable
  jbd2: avoid long hold times of j_state_lock while committing a transaction
  ext4: add ext4_sb_bread() to disambiguate ENOMEM cases

Pull iomap update from Darrick Wong:
 "Fix a memory overflow bug for blocksize < pagesize"

* tag 'iomap-4.21-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  iomap: don't search past page end in iomap_is_partially_uptodate

Pull XFS updates from Darrick Wong:

 - Fix CoW remapping of extremely fragmented file areas

 - Fix a zero-length symlink verifier error

 - Constify some of the rmap owner structures for per-AG metadata

 - Precalculate inode geometry for later use

 - Fix scrub counting problems

 - Don't crash when rtsummary inode is null

 - Fix x32 ioctl operation

 - Fix enum->string mappings for ftrace output

 - Cache realtime summary information in memory

* tag 'xfs-4.21-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (24 commits)
  xfs: reallocate realtime summary cache on growfs
  xfs: stringify scrub types in ftrace output
  xfs: stringify btree cursor types in ftrace output
  xfs: move XFS_INODE_FORMAT_STR mappings to libxfs
  xfs: move XFS_AG_BTREE_CMP_FORMAT_STR mappings to libxfs
  xfs: fix symbolic enum printing in ftrace output
  xfs: fix function pointer type in ftrace format
  xfs: Fix x32 ioctls when cmd numbers differ from ia32.
  xfs: Fix bulkstat compat ioctls on x32 userspace.
  xfs: Align compat attrlist_by_handle with native implementation.
  xfs: require both realtime inodes to mount
  xfs: cache minimum realtime summary level
  xfs: count inode blocks correctly in inobt scrub
  xfs: precalculate cluster alignment in inodes and blocks
  xfs: precalculate inodes and blocks per inode cluster
  xfs: add a block to inode count converter
  xfs: remove xfs_rmap_ag_owner and friends
  xfs: const-ify xfs_owner_info arguments
  xfs: streamline defer op type handling
  xfs: idiotproof defer op type configuration
  ...

Pull ext2, udf, and quota update from Jan Kara:
 "Some ext2 cleanups, a fix for UDF crash on corrupted media, and one
  quota locking fix"

* tag 'fs_for_4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  quota: Lock s_umount in exclusive mode for Q_XQUOTA{ON,OFF} quotactls.
  udf: Fix BUG on corrupted inode
  ext2: change reusable parameter to true when calling mb_cache_entry_create()
  ext2: remove redundant condition check
  ext2: avoid unnecessary operation in ext2_error()

Pull fsnotify updates from Jan Kara:
 "Support for new FAN_OPEN_EXEC event and couple of cleanups around
  fsnotify"

* tag 'fsnotify_for_v4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fanotify: Use inode_is_open_for_write
  fanotify: Make sure to check event_len when copying
  fsnotify/fdinfo: include fdinfo.h for inotify_show_fdinfo()
  fanotify: introduce new event mask FAN_OPEN_EXEC_PERM
  fsnotify: refactor fsnotify_parent()/fsnotify() paired calls when event is on path
  fanotify: introduce new event mask FAN_OPEN_EXEC
  fanotify: return only user requested event types in event mask

Pull dlm updates from David Teigland:
 "This set is entirely trivial fixes, mainly around correct cleanup on
  error paths and improved error checks. One patch adds scheduling in a
  potentially long recovery loop"

* tag 'dlm-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm:
  dlm: fix invalid cluster name warning
  dlm: NULL check before some freeing functions is not needed
  dlm: NULL check before kmem_cache_destroy is not needed
  dlm: fix missing idr_destroy for recover_idr
  dlm: memory leaks on error path in dlm_user_request()
  dlm: lost put_lkb on error path in receive_convert() and receive_unlock()
  dlm: possible memory leak on error path in create_lkb()
  dlm: fixed memory leaks after failed ls_remove_names allocation
  dlm: fix possible call to kfree() for non-initialized pointer
  dlm: Don't swamp the CPU with callbacks queued during recovery
  dlm: don't leak kernel pointer to userspace
  dlm: don't allow zero length names
  dlm: fix invalid free

Pull btrfs updates from David Sterba:
 "New features:

   - swapfile support - after a long time it's here, with some
     limitations where COW design does not work well with the swap
     implementation (nodatacow file, no compression, cannot be
     snapshotted, not possible on multiple devices, ...), as this is the
     most restricted but working setup, we'll try to improve that in the
     future

   - metadata uuid - an optional incompat feature to assign a new
     filesystem UUID without overwriting all metadata blocks, stored
     only in superblock

   - more balance messages are printed to system log, initial is in the
     format of the command line that would be used to start it

  Fixes:

   - tag pages of a snapshot to better separate pages that are involved
     in the snapshot (and need to get synced) from newly dirtied pages
     that could slow down or even livelock the snapshot operation

   - improved check of filesystem id associated with a device during
     scan to detect duplicate devices that could be mixed up during
     mount

   - fix device replace state transitions, eg. when it ends up
     interrupted and reboot tries to restart balance too, or when
     start/cancel ioctls race

   - fix a crash due to a race when quotas are enabled during snapshot
     creation

   - GFP_NOFS/memalloc_nofs_* fixes due to GFP_KERNEL allocations in
     transaction context

   - fix fsync of files with multiple hard links in new directories

   - fix race of send with transaction commits that create snapshots

  Core changes:

   - cleanups:
      * further removals of now-dead fsync code
      * core function for finding free extent has been split and
        provides a base for further cleanups to make the logic more
        understandable
      * removed lot of indirect callbacks for data and metadata inodes
      * simplified refcounting and locking for cloned extent buffers
      * removed redundant function arguments
      * defines converted to enums where appropriate

   - separate reserve for delayed refs from global reserve, update logic
     to do less trickery and ad-hoc heuristics, move out some related
     expensive operations from transaction commit or file truncate

   - dev-replace switched from custom locking scheme to semaphore

   - remove first phase of balance that tried to make some space for the
     relocation by calling shrink and grow, this did not work as
     expected and only introduced more error states due to potential
     resize failures, slightly improves the runtime as the chunks on all
     devices are not needlessly enumerated

   - clone and deduplication now use generic helper that adds a few more
     checks that were missing from the original btrfs implementation of
     the ioctls"

* tag 'for-4.21-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (125 commits)
  btrfs: Fix typos in comments and strings
  btrfs: improve error handling of btrfs_add_link
  Btrfs: use generic_remap_file_range_prep() for cloning and deduplication
  btrfs: Refactor main loop in extent_readpages
  btrfs: Remove 1st shrink/grow phase from balance
  Btrfs: send, fix race with transaction commits that create snapshots
  Btrfs: use nofs context when initializing security xattrs to avoid deadlock
  btrfs: run delayed items before dropping the snapshot
  btrfs: catch cow on deleting snapshots
  btrfs: extent-tree: cleanup one-shot usage of @blocksize in do_walk_down
  Btrfs: scrub, move setup of nofs contexts higher in the stack
  btrfs: scrub: move scrub_setup_ctx allocation out of device_list_mutex
  btrfs: scrub: pass fs_info to scrub_setup_ctx
  btrfs: fix truncate throttling
  btrfs: don't run delayed refs in the end transaction logic
  btrfs: rework btrfs_check_space_for_delayed_refs
  btrfs: add new flushing states for the delayed refs rsv
  btrfs: update may_commit_transaction to use the delayed refs rsv
  btrfs: introduce delayed_refs_rsv
  btrfs: only track ref_heads in delayed_ref_updates
  ...