Use unified assembler syntax (UAL) in assembly files. Divided
syntax is considered deprecated. This will also allow to build
the kernel using LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Use unified assembler syntax (UAL) in headers. Divided syntax is
considered deprecated. This will also allow to build the kernel
using LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Use unified assembler syntax (UAL) in macros. Divided syntax is
considered deprecated. This will also allow to build the kernel
using LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Adds macro to enable UCI entries to be added to AMBA ID tables.

Updates the ID register tables to contain a UCI entry for the A35 ETM
device to allow correct matching of driver in the amba bus code.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

The patches provide an update of amba_device and matching code to handle
the additional registers required for the Class 0x9 (CoreSight) UCI.

The *data pointer in the amba_id is used by the driver to provide extended
ID register values for matching.

CoreSight components where PID/CID pair is currently sufficient for
unique identification need not provide this additional information.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

The CoreSight specification (ARM IHI 0029E), updates the ID register
requirements for components on an AMBA bus, to cover both traditional
ARM Primecell type devices, and newer CoreSight and other components.

The Peripheral ID (PID) / Component ID (CID) pair is extended in certain
cases to uniquely identify components. CoreSight components related to
a single function can share Peripheral ID values, and must be further
identified using a Unique Component Identifier (UCI). e.g. the ETM, CTI,
PMU and Debug hardware of the A35 all share the same PID.

Bits 15:12 of the CID are defined to be the device class.
Class 0xF remains for PrimeCell and legacy components.
Class 0x9 defines the component as CoreSight (CORESIGHT_CID above)
Class 0x0, 0x1, 0xB, 0xE define components that do not have driver support
at present.
Class 0x2-0x8,0xA and 0xD-0xD are presently reserved.

The specification futher defines which classes of device use the standard
CID/PID pair, and when additional ID registers are required.

This patch introduces the amba_cs_uci_id structure which will be used in
all coresight drivers for indentification via the private data pointer in
the amba_id structure.

Existing drivers that currently use the amba_id->data pointer for private
data are updated to use the amba_cs_uci_id->data pointer. Macros and
inline functions are added to simplify this code.
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

While building arm32 allyesconfig, I ran into the following errors:

  arch/arm/lib/xor-neon.c:17:2: error: You should compile this file with
  '-mfloat-abi=softfp -mfpu=neon'

  In file included from lib/raid6/neon1.c:27:
  /home/nathan/cbl/prebuilt/lib/clang/8.0.0/include/arm_neon.h:28:2:
  error: "NEON support not enabled"

Building V=1 showed NEON_FLAGS getting passed along to Clang but
__ARM_NEON__ was not getting defined. Ultimately, it boils down to Clang
only defining __ARM_NEON__ when targeting armv7, rather than armv6k,
which is the '-march' value for allyesconfig.

>From lib/Basic/Targets/ARM.cpp in the Clang source:

  // This only gets set when Neon instructions are actually available, unlike
  // the VFP define, hence the soft float and arch check. This is subtly
  // different from gcc, we follow the intent which was that it should be set
  // when Neon instructions are actually available.
  if ((FPU & NeonFPU) && !SoftFloat && ArchVersion >= 7) {
    Builder.defineMacro("__ARM_NEON", "1");
    Builder.defineMacro("__ARM_NEON__");
    // current AArch32 NEON implementations do not support double-precision
    // floating-point even when it is present in VFP.
    Builder.defineMacro("__ARM_NEON_FP",
                        "0x" + Twine::utohexstr(HW_FP & ~HW_FP_DP));
  }

Ard Biesheuvel recommended explicitly adding '-march=armv7-a' at the
beginning of the NEON_FLAGS definitions so that __ARM_NEON__ always gets
definined by Clang. This doesn't functionally change anything because
that code will only run where NEON is supported, which is implicitly
armv7.

Link: https://github.com/ClangBuiltLinux/linux/issues/287Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

machine_crash_nonpanic_core() does this:

	while (1)
		cpu_relax();

because the kernel has crashed, and we have no known safe way to deal
with the CPU.  So, we place the CPU into an infinite loop which we
expect it to never exit - at least not until the system as a whole is
reset by some method.

In the absence of erratum 754327, this code assembles to:

	b	.

In other words, an infinite loop.  When erratum 754327 is enabled,
this becomes:

1:	dmb
	b	1b

It has been observed that on some systems (eg, OMAP4) where, if a
crash is triggered, the system tries to kexec into the panic kernel,
but fails after taking the secondary CPU down - placing it into one
of these loops.  This causes the system to livelock, and the most
noticable effect is the system stops after issuing:

	Loading crashdump kernel...

to the system console.

The tested as working solution I came up with was to add wfe() to
these infinite loops thusly:

	while (1) {
		cpu_relax();
		wfe();
	}

which, without 754327 builds to:

1:	wfe
	b	1b

or with 754327 is enabled:

1:	dmb
	wfe
	b	1b

Adding "wfe" does two things depending on the environment we're running
under:
- where we're running on bare metal, and the processor implements
  "wfe", it stops us spinning endlessly in a loop where we're never
  going to do any useful work.
- if we're running in a VM, it allows the CPU to be given back to the
  hypervisor and rescheduled for other purposes (maybe a different VM)
  rather than wasting CPU cycles inside a crashed VM.

However, in light of erratum 794072, Will Deacon wanted to see 10 nops
as well - which is reasonable to cover the case where we have erratum
754327 enabled _and_ we have a processor that doesn't implement the
wfe hint.

So, we now end up with:

1:      wfe
        b       1b

when erratum 754327 is disabled, or:

1:      dmb
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        nop
        wfe
        b       1b

when erratum 754327 is enabled.  We also get the dmb + 10 nop
sequence elsewhere in the kernel, in terminating loops.

This is reasonable - it means we get the workaround for erratum
794072 when erratum 754327 is enabled, but still relinquish the dead
processor - either by placing it in a lower power mode when wfe is
implemented as such or by returning it to the hypervisior, or in the
case where wfe is a no-op, we use the workaround specified in erratum
794072 to avoid the problem.

These as two entirely orthogonal problems - the 10 nops addresses
erratum 794072, and the wfe is an optimisation that makes the system
more efficient when crashed either in terms of power consumption or
by allowing the host/other VMs to make use of the CPU.

I don't see any reason not to use kexec() inside a VM - it has the
potential to provide automated recovery from a failure of the VMs
kernel with the opportunity for saving a crashdump of the failure.
A panic() with a reboot timeout won't do that, and reading the
libvirt documentation, setting on_reboot to "preserve" won't either
(the documentation states "The preserve action for an on_reboot event
is treated as a destroy".)  Surely it has to be a good thing to
avoiding having CPUs spinning inside a VM that is doing no useful
work.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

It looks like usage of CONFIG_FLASH_{MEM_BASE,SIZE} is limited with:

arch/arm/mm/proc-arm740.S
arch/arm/mm/proc-arm940.S
arch/arm/mm/proc-arm946.S

So it might look confusing to see the option for anything except these.
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Remove unneeded semicolon.

[vladimir] proper tags in subject line
Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Acked-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

ARMv8M introduces support for Security extension to M class, among
other things it affects exception handling, especially, encoding of
EXC_RETURN.

The new bits have been added:

Bit [6]	Secure or Non-secure stack
Bit [5]	Default callee register stacking
Bit [0]	Exception Secure

which conflicts with hard-coded value of EXC_RETURN:

In fact, we only care of few bits:

Bit [3]	 Mode (0 - Handler, 1 - Thread)
Bit [2]	 Stack pointer selection (0 - Main, 1 - Process)

We can toggle only those bits and left other bits as they were on
exception entry.

It is basically, what patch does - saves EXC_RETURN when we do
transition form Thread to Handler mode (it is first svc), so later
saved value is used instead of EXC_RET_THREADMODE_PROCESSSTACK.
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Convert the conditional infix to a postfix to make sure this inline
assembly is unified syntax. Since gcc assumes non-unified syntax
when emitting ARM instructions, make sure to define the syntax as
unified.

This allows to use LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Convert the conditional infix to a postfix to make sure this inline
assembly is unified syntax. Since gcc assumes non-unified syntax
when emitting ARM instructions, make sure to define the syntax as
unified.

This allows to use LLVM's integrated assembler.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

The macro str8w takes 10 arguments, abort being the 10th. In this
particular instantiation the abort argument is passed as 11th
argument leading to an error when using LLVM's integrated
assembler:
  <instantiation>:46:47: error: too many positional arguments
    str8w r0, r3, r4, r5, r6, r7, r8, r9, ip, , abort=19f
                                                ^
  arch/arm/lib/copy_template.S:277:5: note: while in macro instantiation
  18: forward_copy_shift pull=24 push=8
      ^

The argument is not used in the macro hence this does not change
code generation.
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

The max_low_pfn value must be set before sparse_init() is called to
keep the early memblock allocations and frees balanced for kmemleak
initialization when sparsemem is enabled.

This commit accomplishes that by replacing the local variables min,
max_low, and max_high with the global limit variables min_low_pfn,
max_low_pfn, and max_pfn respectively in bootmem_init(). The global
variables are initialized directly by find_limits() and used in the
remainder of the function.

Fixes: 9099daed ("mm: kmemleak: avoid using __va() on addresses that don't have a lowmem mapping")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Doug Berger <opendmb@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

This is used when mmapping the PCI resource* files in sys.  Because ARM
currently lacks an implementation of pgprot_device(), it falls back to
pgprot_uncached() (Strongly Ordered), but we should be able to use
Device memory instead.

Doing this speeds up large writes to the resource files by about 40% on
one of my systems.  It also ensures that mmaps on these resources use
the same memory type as ioremap().
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

As of commit 7484c727 ("ARM: realview: delete the RealView board
files"), the ARM Timer and Watchdog Unit is instantiated from DT only.
Moreover, the driver is selected from ARCH_MULTIPLATFORM platforms only,
which implies OF, TIMER_OF, and COMMON_CLK.

Hence remove all unused legacy infrastructure from the driver.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

According to the ARM Cortex-A5 and Cortex-A9 Technical Reference
Manuals, SCU stands for "Snoop Control Unit".
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Since commit ad67b74d ("printk: hash addresses printed with
%p"), the virtual memory layout printed during boot up contains "ptrval"
instead of actual addresses:

    Memory: 501296K/524288K available (6144K kernel code, 528K rwdata, 1944K rodata, 1024K init, 7584K bss, 22992K reserved, 0K cma-reserved)
    Virtual kernel memory layout:
	vector  : 0xffff0000 - 0xffff1000   (   4 kB)
	fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
	vmalloc : 0xe0800000 - 0xff800000   ( 496 MB)
	lowmem  : 0xc0000000 - 0xe0000000   ( 512 MB)
	modules : 0xbf000000 - 0xc0000000   (  16 MB)
	  .text : 0x(ptrval) - 0x(ptrval)   (7136 kB)
	  .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
	  .data : 0x(ptrval) - 0x(ptrval)   ( 529 kB)
	   .bss : 0x(ptrval) - 0x(ptrval)   (7585 kB)

Instead of changing the printing to "%px", and leaking virtual memory
layout information again, just remove the printing completely, cfr. e.g.
commits 071929db ("arm64: Stop printing the virtual memory
layout") and  31833332 ("m68k/mm: Stop printing the virtual
memory layout").

All interesting information (actual section sizes) is already printed by
mem_init_print_info() just above anyway.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

This option is not supported by lld:

    ld.lld: error: unknown argument: -p

This has been a no-op in binutils since 2004 (see commit dea514f51da1 in
that tree). Given that the lowest officially supported of binutils for
the kernel is 2.20, which was released in 2009, nobody needs this flag
around so just remove it. Commit 1a381d4a ("arm64: remove no-op -p
linker flag") did the same for arm64.
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Update the comment because we don't set the pointer to NULL anymore.
Also use the correct pointer name 'dma_ops' instead of 'dma_map_ops'.

Fixes: 1874619a ("ARM: dma-mapping: Set proper DMA ops in arm_iommu_detach_device()")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Currently, init_static_idmap() installs some page table entries to
cover the identity mapped part of the kernel image (which is only
about 160 bytes in size in a multi_v7_defconfig Thumb2 build), and
calls flush_cache_louis() to ensure that the updates are visible
to the page table walker on the same core.

When running under virtualization, flush_cache_louis() may take more
than 10 seconds to complete:

[    0.108192] Setting up static identity map for 0x40300000 - 0x403000a0
[   13.078127] rcu: Hierarchical SRCU implementation.

This is due to the fact that set/way ops are not virtualizable, and so
KVM may trap each one, resulting in a substantial delay.

Since only LPAE capable CPUs may execute under virtualization, and
considering that LPAE capable CPUs are guaranteed to have cache
coherent page table walkers (per the architecture), let's only
perform this cache maintenance on non-LPAE cores.

Cc: Will Deacon <will.deacon@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Pull more Kbuild updates from Masahiro Yamada:

 - improve boolinit.cocci and use_after_iter.cocci semantic patches

 - fix alignment for kallsyms

 - move 'asm goto' compiler test to Kconfig and clean up jump_label
   CONFIG option

 - generate asm-generic wrappers automatically if arch does not
   implement mandatory UAPI headers

 - remove redundant generic-y defines

 - misc cleanups

* tag 'kbuild-v4.21-3' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kconfig: rename generated .*conf-cfg to *conf-cfg
  kbuild: remove unnecessary stubs for archheader and archscripts
  kbuild: use assignment instead of define ... endef for filechk_* rules
  arch: remove redundant UAPI generic-y defines
  kbuild: generate asm-generic wrappers if mandatory headers are missing
  arch: remove stale comments "UAPI Header export list"
  riscv: remove redundant kernel-space generic-y
  kbuild: change filechk to surround the given command with { }
  kbuild: remove redundant target cleaning on failure
  kbuild: clean up rule_dtc_dt_yaml
  kbuild: remove UIMAGE_IN and UIMAGE_OUT
  jump_label: move 'asm goto' support test to Kconfig
  kallsyms: lower alignment on ARM
  scripts: coccinelle: boolinit: drop warnings on named constants
  scripts: coccinelle: check for redeclaration
  kconfig: remove unused "file" field of yylval union
  nds32: remove redundant kernel-space generic-y
  nios2: remove unneeded HAS_DMA define

Pull perf tooling updates form Ingo Molnar:
 "A final batch of perf tooling changes: mostly fixes and small
  improvements"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (29 commits)
  perf session: Add comment for perf_session__register_idle_thread()
  perf thread-stack: Fix thread stack processing for the idle task
  perf thread-stack: Allocate an array of thread stacks
  perf thread-stack: Factor out thread_stack__init()
  perf thread-stack: Allow for a thread stack array
  perf thread-stack: Avoid direct reference to the thread's stack
  perf thread-stack: Tidy thread_stack__bottom() usage
  perf thread-stack: Simplify some code in thread_stack__process()
  tools gpio: Allow overriding CFLAGS
  tools power turbostat: Override CFLAGS assignments and add LDFLAGS to build command
  tools thermal tmon: Allow overriding CFLAGS assignments
  tools power x86_energy_perf_policy: Override CFLAGS assignments and add LDFLAGS to build command
  perf c2c: Increase the HITM ratio limit for displayed cachelines
  perf c2c: Change the default coalesce setup
  perf trace beauty ioctl: Beautify USBDEVFS_ commands
  perf trace beauty: Export function to get the files for a thread
  perf trace: Wire up ioctl's USBDEBFS_ cmd table generator
  perf beauty ioctl: Add generator for USBDEVFS_ ioctl commands
  tools headers uapi: Grab a copy of usbdevice_fs.h
  perf trace: Store the major number for a file when storing its pathname
  ...

The semantics of what "in core" means for the mincore() system call are
somewhat unclear, but Linux has always (since 2.3.52, which is when
mincore() was initially done) treated it as "page is available in page
cache" rather than "page is mapped in the mapping".

The problem with that traditional semantic is that it exposes a lot of
system cache state that it really probably shouldn't, and that users
shouldn't really even care about.

So let's try to avoid that information leak by simply changing the
semantics to be that mincore() counts actual mapped pages, not pages
that might be cheaply mapped if they were faulted (note the "might be"
part of the old semantics: being in the cache doesn't actually guarantee
that you can access them without IO anyway, since things like network
filesystems may have to revalidate the cache before use).

In many ways the old semantics were somewhat insane even aside from the
information leak issue.  From the very beginning (and that beginning is
a long time ago: 2.3.52 was released in March 2000, I think), the code
had a comment saying

  Later we can get more picky about what "in core" means precisely.

and this is that "later".  Admittedly it is much later than is really
comfortable.

NOTE! This is a real semantic change, and it is for example known to
change the output of "fincore", since that program literally does a
mmmap without populating it, and then doing "mincore()" on that mapping
that doesn't actually have any pages in it.

I'm hoping that nobody actually has any workflow that cares, and the
info leak is real.

We may have to do something different if it turns out that people have
valid reasons to want the old semantics, and if we can limit the
information leak sanely.

Cc: Kevin Easton <kevin@guarana.org>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Masatake YAMATO <yamato@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit 594cc251 ("make 'user_access_begin()' do 'access_ok()'")
broke both alpha and SH booting in qemu, as noticed by Guenter Roeck.

It turns out that the bug wasn't actually in that commit itself (which
would have been surprising: it was mostly a no-op), but in how the
addition of access_ok() to the strncpy_from_user() and strnlen_user()
functions now triggered the case where those functions would test the
access of the very last byte of the user address space.

The string functions actually did that user range test before too, but
they did it manually by just comparing against user_addr_max().  But
with user_access_begin() doing the check (using "access_ok()"), it now
exposed problems in the architecture implementations of that function.

For example, on alpha, the access_ok() helper macro looked like this:

  #define __access_ok(addr, size) \
        ((get_fs().seg & (addr | size | (addr+size))) == 0)

and what it basically tests is of any of the high bits get set (the
USER_DS masking value is 0xfffffc0000000000).

And that's completely wrong for the "addr+size" check.  Because it's
off-by-one for the case where we check to the very end of the user
address space, which is exactly what the strn*_user() functions do.

Why? Because "addr+size" will be exactly the size of the address space,
so trying to access the last byte of the user address space will fail
the __access_ok() check, even though it shouldn't.  As a result, the
user string accessor functions failed consistently - because they
literally don't know how long the string is going to be, and the max
access is going to be that last byte of the user address space.

Side note: that alpha macro is buggy for another reason too - it re-uses
the arguments twice.

And SH has another version of almost the exact same bug:

  #define __addr_ok(addr) \
        ((unsigned long __force)(addr) < current_thread_info()->addr_limit.seg)

so far so good: yes, a user address must be below the limit.  But then:

  #define __access_ok(addr, size)         \
        (__addr_ok((addr) + (size)))

is wrong with the exact same off-by-one case: the case when "addr+size"
is exactly _equal_ to the limit is actually perfectly fine (think "one
byte access at the last address of the user address space")

The SH version is actually seriously buggy in another way: it doesn't
actually check for overflow, even though it did copy the _comment_ that
talks about overflow.

So it turns out that both SH and alpha actually have completely buggy
implementations of access_ok(), but they happened to work in practice
(although the SH overflow one is a serious serious security bug, not
that anybody likely cares about SH security).

This fixes the problems by using a similar macro on both alpha and SH.
It isn't trying to be clever, the end address is based on this logic:

        unsigned long __ao_end = __ao_a + __ao_b - !!__ao_b;

which basically says "add start and length, and then subtract one unless
the length was zero".  We can't subtract one for a zero length, or we'd
just hit an underflow instead.

For a lot of access_ok() users the length is a constant, so this isn't
actually as expensive as it initially looks.
Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull fscrypt updates from Ted Ts'o:
 "Add Adiantum support for fscrypt"

* tag 'fscrypt_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/fscrypt:
  fscrypt: add Adiantum support

Pull ext4 bug fixes from Ted Ts'o:
 "Fix a number of ext4 bugs"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix special inode number checks in __ext4_iget()
  ext4: track writeback errors using the generic tracking infrastructure
  ext4: use ext4_write_inode() when fsyncing w/o a journal
  ext4: avoid kernel warning when writing the superblock to a dead device
  ext4: fix a potential fiemap/page fault deadlock w/ inline_data
  ext4: make sure enough credits are reserved for dioread_nolock writes

Pull dma-mapping fixes from Christoph Hellwig:
 "Fix various regressions introduced in this cycles:

   - fix dma-debug tracking for the map_page / map_single
     consolidatation

   - properly stub out DMA mapping symbols for !HAS_DMA builds to avoid
     link failures

   - fix AMD Gart direct mappings

   - setup the dma address for no kernel mappings using the remap
     allocator"

* tag 'dma-mapping-4.21-1' of git://git.infradead.org/users/hch/dma-mapping:
  dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING for remapped allocations
  x86/amd_gart: fix unmapping of non-GART mappings
  dma-mapping: remove a few unused exports
  dma-mapping: properly stub out the DMA API for !CONFIG_HAS_DMA
  dma-mapping: remove dmam_{declare,release}_coherent_memory
  dma-mapping: implement dmam_alloc_coherent using dmam_alloc_attrs
  dma-mapping: implement dma_map_single_attrs using dma_map_page_attrs

Merge tag 'tag-chrome-platform-for-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/bleung/chrome-platform

Pull chrome platform updates from Benson Leung:

 - Changes for EC_MKBP_EVENT_SENSOR_FIFO handling.

 - Also, maintainership changes. Olofj out, Enric balletbo in.

* tag 'tag-chrome-platform-for-v4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/bleung/chrome-platform:
  MAINTAINERS: add maintainers for ChromeOS EC sub-drivers
  MAINTAINERS: platform/chrome: Add Enric as a maintainer
  MAINTAINERS: platform/chrome: remove myself as maintainer
  platform/chrome: don't report EC_MKBP_EVENT_SENSOR_FIFO as wakeup
  platform/chrome: straighten out cros_ec_get_{next,host}_event() error codes

Pull hwspinlock updates from Bjorn Andersson:
 "This adds support for the hardware semaphores found in STM32MP1"

* tag 'hwlock-v4.21' of git://github.com/andersson/remoteproc:
  hwspinlock: fix return value check in stm32_hwspinlock_probe()
  hwspinlock: add STM32 hwspinlock device
  dt-bindings: hwlock: Document STM32 hwspinlock bindings

Add support for the Adiantum encryption mode to fscrypt.  Adiantum is a
tweakable, length-preserving encryption mode with security provably
reducible to that of XChaCha12 and AES-256, subject to a security bound.
It's also a true wide-block mode, unlike XTS.  See the paper
"Adiantum: length-preserving encryption for entry-level processors"
(https://eprint.iacr.org/2018/720.pdf) for more details.  Also see
commit 059c2a4d ("crypto: adiantum - add Adiantum support").

On sufficiently long messages, Adiantum's bottlenecks are XChaCha12 and
the NH hash function.  These algorithms are fast even on processors
without dedicated crypto instructions.  Adiantum makes it feasible to
enable storage encryption on low-end mobile devices that lack AES
instructions; currently such devices are unencrypted.  On ARM Cortex-A7,
on 4096-byte messages Adiantum encryption is about 4 times faster than
AES-256-XTS encryption; decryption is about 5 times faster.

In fscrypt, Adiantum is suitable for encrypting both file contents and
names.  With filenames, it fixes a known weakness: when two filenames in
a directory share a common prefix of >= 16 bytes, with CTS-CBC their
encrypted filenames share a common prefix too, leaking information.
Adiantum does not have this problem.

Since Adiantum also accepts long tweaks (IVs), it's also safe to use the
master key directly for Adiantum encryption rather than deriving
per-file keys, provided that the per-file nonce is included in the IVs
and the master key isn't used for any other encryption mode.  This
configuration saves memory and improves performance.  A new fscrypt
policy flag is added to allow users to opt-in to this configuration.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Pull documentation fixes from Jonathan Corbet:
 "A handful of late-arriving documentation fixes"

* tag 'docs-5.0-fixes' of git://git.lwn.net/linux:
  doc: filesystems: fix bad references to nonexistent ext4.rst file
  Documentation/admin-guide: update URL of LKML information link
  Docs/kernel-api.rst: Remove blk-tag.c reference

Pull firewire fixlet from Stefan Richter:
 "Remove an explicit dependency in Kconfig which is implied by another
  dependency"

* tag 'firewire-update' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394:
  firewire: Remove depends on HAS_DMA in case of platform dependency

Pull block updates and fixes from Jens Axboe:

 - Pulled in MD changes that Shaohua had queued up for 4.21.

   Unfortunately we lost Shaohua late 2018, I'm sending these in on his
   behalf.

 - In conjunction with the above, I added a CREDITS entry for Shaoua.

 - sunvdc queue restart fix (Ming)

* tag 'for-linus-20190104' of git://git.kernel.dk/linux-block:
  Add CREDITS entry for Shaohua Li
  block: sunvdc: don't run hw queue synchronously from irq context
  md: fix raid10 hang issue caused by barrier
  raid10: refactor common wait code from regular read/write request
  md: remvoe redundant condition check
  lib/raid6: add option to skip algo benchmarking
  lib/raid6: sort algos in rough performance order
  lib/raid6: check for assembler SSSE3 support
  lib/raid6: avoid __attribute_const__ redefinition
  lib/raid6: add missing include for raid6test
  md: remove set but not used variable 'bi_rdev'

Pull drm fixes from Dave Airlie:
 "Happy New Year, just decloaking from leave to get some stuff from the
  last week in before rc1:

  core:
   - two regression fixes for damage blob and atomic

  i915 gvt:
   - Some missed GVT fixes from the original pull

  amdgpu:
   - new PCI IDs
   - SR-IOV fixes
   - DC fixes
   - Vega20 fixes"

* tag 'drm-next-2019-01-05' of git://anongit.freedesktop.org/drm/drm: (53 commits)
  drm: Put damage blob when destroy plane state
  drm: fix null pointer dereference on null state pointer
  drm/amdgpu: Add new VegaM pci id
  drm/ttm: Use drm_debug_printer for all ttm_bo_mem_space_debug output
  drm/amdgpu: add Vega20 PSP ASD firmware loading
  drm/amd/display: Fix MST dp_blank REG_WAIT timeout
  drm/amd/display: validate extended dongle caps
  drm/amd/display: Use div_u64 for flip timestamp ns to ms
  drm/amdgpu/uvd:Change uvd ring name convention
  drm/amd/powerplay: add Vega20 LCLK DPM level setting support
  drm/amdgpu: print process info when job timeout
  drm/amdgpu/nbio7.4: add hw bug workaround for vega20
  drm/amdgpu/nbio6.1: add hw bug workaround for vega10/12
  drm/amd/display: Optimize passive update planes.
  drm/amd/display: verify lane status before exiting verify link cap
  drm/amd/display: Fix bug with not updating VSP infoframe
  drm/amd/display: Add retry to read ddc_clock pin
  drm/amd/display: Don't skip link training for empty dongle
  drm/amd/display: Wait edp HPD to high in detect_sink
  drm/amd/display: fix surface update sequence
  ...

Pull rdma fixes from Jason Gunthorpe:
 "Over the break a few defects were found, so this is a -rc style pull
  request of various small things that have been posted.

   - An attempt to shorten RCU grace period driven delays showed crashes
     during heavier testing, and has been entirely reverted

   - A missed merge/rebase error between the advise_mr and ib_device_ops
     series

   - Some small static analysis driven fixes from Julia and Aditya

   - Missed ability to create a XRC_INI in the devx verbs interop
     series"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
  infiniband/qedr: Potential null ptr dereference of qp
  infiniband: bnxt_re: qplib: Check the return value of send_message
  IB/ipoib: drop useless LIST_HEAD
  IB/core: Add advise_mr to the list of known ops
  Revert "IB/mlx5: Fix long EEH recover time with NVMe offloads"
  IB/mlx5: Allow XRC INI usage via verbs in DEVX context

Pull fbdev updates from Bartlomiej Zolnierkiewicz:
 "This time the pull request is really small.

  The most notable changes are fixing fbcon to not cause crash on
  unregister_framebuffer() operation when there is more than one
  framebuffer, adding config option to center the bootup logo and making
  FB_BACKLIGHT config option tristate (which in turn uncovered incorrect
  FB_BACKLIGHT usage by DRM's nouveau driver).

  Summary:

   - fix fbcon to not cause crash on unregister_framebuffer() when there
     is more than one framebuffer (Noralf Trønnes)

   - improve support for small rotated displays (Peter Rosin)

   - fix probe failure handling in udlfb driver (Dan Carpenter)

   - add config option to center the bootup logo (Peter Rosin)

   - make FB_BACKLIGHT config option tristate (Rob Clark)

   - remove superfluous HAS_DMA dependency for goldfishfb driver (Geert
     Uytterhoeven)

   - misc fixes (Alexey Khoroshilov, YueHaibing, Colin Ian King, Lubomir
     Rintel)

   - misc cleanups (Yangtao Li, Wen Yang)

  also there is DRM's nouveau driver fix for wrong FB_BACKLIGHT config
  option usage (FB_BACKLIGHT is for internal fbdev subsystem use only)"

* tag 'fbdev-v4.21' of git://github.com/bzolnier/linux:
  drm/nouveau: fix incorrect FB_BACKLIGHT usage in Kconfig
  fbdev: fbcon: Fix unregister crash when more than one framebuffer
  fbdev: Remove depends on HAS_DMA in case of platform dependency
  pxa168fb: trivial typo fix
  fbdev: fsl-diu: remove redundant null check on cmap
  fbdev: omap2: omapfb: convert to DEFINE_SHOW_ATTRIBUTE
  fbdev: uvesafb: fix spelling mistake "memoery" -> "memory"
  fbdev: fbmem: add config option to center the bootup logo
  fbdev: fbmem: make fb_show_logo_line return the end instead of the height
  video: fbdev: pxafb: Fix "WARNING: invalid free of devm_ allocated data"
  fbdev: fbmem: behave better with small rotated displays and many CPUs
  video: clps711x-fb: release disp device node in probe()
  fbdev: make FB_BACKLIGHT a tristate
  udlfb: fix some inconsistent NULL checking

Pull i2c updates from Wolfram Sang:
 "I2C has only driver updates for you this time.

  Mostly new IDs/DT compatibles, also SPDX conversions, small cleanups.
  STM32F7 got FastMode+ and PM support, Axxia some reliabilty
  improvements"

* 'i2c/for-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux: (26 commits)
  i2c: Add Actions Semiconductor Owl family S700 I2C support
  dt-bindings: i2c: Add S700 support for Actions Semi Soc's
  i2c: ismt: Add support for Intel Cedar Fork
  i2c: tegra: Switch to SPDX identifier
  i2c: tegra: Add missing kerneldoc for some fields
  i2c: tegra: Cleanup kerneldoc comments
  i2c: axxia: support sequence command mode
  dt-bindings: i2c: rcar: Add r8a774c0 support
  dt-bindings: i2c: sh_mobile: Add r8a774c0 support
  i2c: sh_mobile: Add support for r8a774c0 (RZ/G2E)
  i2c: i2c-cros-ec-tunnel: Switch to SPDX identifier.
  i2c: powermac: Use of_node_name_eq for node name comparisons
  i2c-axxia: check for error conditions first
  i2c-axxia: dedicated function to set client addr
  dt-bindings: i2c: Use correct vendor prefix for Atmel
  i2c: tegra: replace spin_lock_irqsave with spin_lock in ISR
  eeprom: at24: add support for 24c2048
  dt-bindings: eeprom: at24: add "atmel,24c2048" compatible string
  i2c: i2c-stm32f7: add PM Runtime support
  i2c: sh_mobile: add support for r8a77990 (R-Car E3)
  ...