Provide a software-based implementation of the priviledged no access
support found in ARMv8.1.

Userspace pages are mapped using a different domain number from the
kernel and IO mappings.  If we switch the user domain to "no access"
when we enter the kernel, we can prevent the kernel from touching
userspace.

However, the kernel needs to be able to access userspace via the
various user accessor functions.  With the wrapping in the previous
patch, we can temporarily enable access when the kernel needs user
access, and re-disable it afterwards.

This allows us to trap non-intended accesses to userspace, eg, caused
by an inadvertent dereference of the LIST_POISON* values, which, with
appropriate user mappings setup, can be made to succeed.  This in turn
can allow use-after-free bugs to be further exploited than would
otherwise be possible.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Provide hooks into the kernel entry and exit paths to permit control
of userspace visibility to the kernel.  The intended use is:

- on entry to kernel from user, uaccess_disable will be called to
  disable userspace visibility
- on exit from kernel to user, uaccess_enable will be called to
  enable userspace visibility
- on entry from a kernel exception, uaccess_save_and_disable will be
  called to save the current userspace visibility setting, and disable
  access
- on exit from a kernel exception, uaccess_restore will be called to
  restore the userspace visibility as it was before the exception
  occurred.

These hooks allows us to keep userspace visibility disabled for the
vast majority of the kernel, except for localised regions where we
want to explicitly access userspace.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The following structure is just asking for trouble:

 #ifdef CONFIG_symbol
	.macro foo
	...
	.endm
	.macro bar
	...
	.endm
	.macro baz
	...
	.endm
 #else
	.macro foo
	...
	.endm
	.macro bar
	...
	.endm
 #ifdef CONFIG_symbol2
	.macro baz
	...
	.endm
 #else
	.macro baz
	...
	.endm
 #endif
 #endif

such as one defintion being updated, but the other definitions miss out.
Where the contents of a macro needs to be conditional, the hint is in
the first clause of this very sentence.  "contents" "conditional".  Not
multiple separate definitions, especially not when much of the macro
is the same between different configs.

This patch fixes this bad style, which had caused the Thumb2 code to
miss-out on the uaccess updates.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The only caller of cpu_die() on ARM is arch_cpu_idle_dead(), so
let's simplify the code by renaming cpu_die() to
arch_cpu_idle_dead(). While were here, drop the __ref annotation
because __cpuinit is gone nowadays.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Provide uaccess_save_and_enable() and uaccess_restore() to permit
control of userspace visibility to the kernel, and hook these into
the appropriate places in the kernel where we need to access
userspace.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Improve the do_ldrd_abort macro code - firstly, it inefficiently checks
for the LDRD encoding by doing a multi-stage test of various bits.  This
can be simplified by generating a mask, bitmasking the instruction and
then comparing the result.

Secondly, we want to be able to test the result rather than branching
to do_DataAbort, so remove the branch at the end and rename the macro
to 'teq_ldrd' to reflect it's new usage.  teq_ldrd macro returns 'eq'
if the instruction was a LDRD.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The audit code looks like it's been written to cope with being called
with IRQs enabled.  However, it's unclear whether IRQs should be
enabled or disabled when calling the syscall tracing infrastructure.

Right now, sometimes we call this with IRQs enabled, and other times
with IRQs disabled.  Opt for IRQs being enabled for consistency.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Make the "fast" syscall return path fast again.  The addition of IRQ
tracing and context tracking has made this path grossly inefficient.
We can do much better if these options are enabled if we save the
syscall return code on the stack - we then don't need to save a bunch
of registers around every single callout to C code.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

There's no need for this macro, it can use a default for the
condition argument.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The user assembly for byte and word accesses was virtually identical.
Rather than duplicating this, use a macro instead.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

DOMAIN_TABLE is not used; in any case, it aliases to the kernel domain.
Remove this definition.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Keep the machine vectors in its own domain to avoid software based
user access control from making the vector code inaccessible, and
thereby deadlocking the machine.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Since we switched to early trap initialisation in 94e5a85b
("ARM: earlier initialization of vectors page") we haven't been writing
directly to the vectors page, and so there's no need for this domain
to be in manager mode.  Switch it to client mode.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Provide a macro to generate the mask for a domain, rather than using
domain_val(, DOMAIN_MANAGER) which won't work when CPU_USE_DOMAINS
is turned off.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Rather than modifying both the domain access control register and our
per-thread copy, modify only the domain access control register, and
use the per-thread copy to save and restore the register over context
switches.  We can also avoid the explicit initialisation of the
init thread_info structure.

This allows us to avoid needing to gain access to the thread information
at the uaccess control sites.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

All architectures except arm that define DMA_ERROR_CODE are casting it
to (dma_addr_t) - as it is always compared to dma_addr_t in arm as well
this could be harmonized.
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Use BIT_MASK() and BIT_WORD() rather than hard-coding the size
of the "long" type.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The chain of of_address_to_resource() and ioremap() can be replaced
with of_iomap().
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Add early fixmap support, initially to support permanent, fixed
mapping support for early console. A temporary, early pte is
created which is migrated to a permanent mapping in paging_init.
This is also needed since the attributes may change as the memory
types are initialized. The 3MiB range of fixmap spans two pte
tables, but currently only one pte is created for early fixmap
support.

Re-add FIX_KMAP_BEGIN to the index calculation in highmem.c since
the index for kmap does not start at zero anymore. This reverts
4221e2e6 ("ARM: 8031/1: fixmap: remove FIX_KMAP_BEGIN and
FIX_KMAP_END") to some extent.

Cc: Mark Salter <msalter@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laura Abbott <lauraa@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

U-Boot is often used to boot the kernel on ARM boards, but uImage
is not built by "make all", so we are often inclined to do
"make all uImage" to generate DTBs, modules and uImage in a single
command, but we should notice a pitfall behind it.  In fact,
"make all uImage" could generate an invalid uImage if it is run with
the parallel option (-j).

You can reproduce this problem with the following procedure:

[1] First, build "all" and "uImage" separately.
    You will get a valid uImage

  $ git clean -f -x -d
  $ export CROSS_COMPILE=<your-tools-prefix>
  $ make -s -j8 ARCH=arm multi_v7_defconfig
  $ make -s -j8 ARCH=arm all
  $ make -j8 ARCH=arm UIMAGE_LOADADDR=0x80208000 uImage
    CHK     include/config/kernel.release
    CHK     include/generated/uapi/linux/version.h
    CHK     include/generated/utsrelease.h
  make[1]: `include/generated/mach-types.h' is up to date.
    CHK     include/generated/timeconst.h
    CHK     include/generated/bounds.h
    CHK     include/generated/asm-offsets.h
    CALL    scripts/checksyscalls.sh
    CHK     include/generated/compile.h
    Kernel: arch/arm/boot/Image is ready
    Kernel: arch/arm/boot/zImage is ready
    UIMAGE  arch/arm/boot/uImage
  Image Name:   Linux-4.2.0-rc5-00156-gdd2384a7-d
  Created:      Sat Aug  8 23:21:35 2015
  Image Type:   ARM Linux Kernel Image (uncompressed)
  Data Size:    6138648 Bytes = 5994.77 kB = 5.85 MB
  Load Address: 80208000
  Entry Point:  80208000
    Image arch/arm/boot/uImage is ready
  $ ls -l arch/arm/boot/*Image
  -rwxrwxr-x 1 masahiro masahiro 13766656 Aug  8 23:20 arch/arm/boot/Image
  -rw-rw-r-- 1 masahiro masahiro  6138712 Aug  8 23:21 arch/arm/boot/uImage
  -rwxrwxr-x 1 masahiro masahiro  6138648 Aug  8 23:20 arch/arm/boot/zImage

[2] Update some source file(s)

  $ touch init/main.c

[3] Then, re-build "all" and "uImage" simultaneously.
    You will get an invalid uImage at random.

  $ make -j8 ARCH=arm UIMAGE_LOADADDR=0x80208000 all uImage
    CHK     include/config/kernel.release
    CHK     include/generated/uapi/linux/version.h
    CHK     include/generated/utsrelease.h
  make[1]: `include/generated/mach-types.h' is up to date.
    CHK     include/generated/timeconst.h
    CHK     include/generated/bounds.h
    CHK     include/generated/asm-offsets.h
    CALL    scripts/checksyscalls.sh
    CC      init/main.o
    CHK     include/generated/compile.h
    LD      init/built-in.o
    LINK    vmlinux
    LD      vmlinux.o
    MODPOST vmlinux.o
    GEN     .version
    CHK     include/generated/compile.h
    UPD     include/generated/compile.h
    CC      init/version.o
    LD      init/built-in.o
    KSYM    .tmp_kallsyms1.o
    KSYM    .tmp_kallsyms2.o
    LD      vmlinux
    SORTEX  vmlinux
    SYSMAP  System.map
    OBJCOPY arch/arm/boot/Image
    Building modules, stage 2.
    Kernel: arch/arm/boot/Image is ready
    GZIP    arch/arm/boot/compressed/piggy.gzip
    AS      arch/arm/boot/compressed/piggy.gzip.o
    Kernel: arch/arm/boot/Image is ready
    LD      arch/arm/boot/compressed/vmlinux
    GZIP    arch/arm/boot/compressed/piggy.gzip
    OBJCOPY arch/arm/boot/zImage
    Kernel: arch/arm/boot/zImage is ready
    UIMAGE  arch/arm/boot/uImage
  Image Name:   Linux-4.2.0-rc5-00156-gdd2384a7-d
  Created:      Sat Aug  8 23:23:14 2015
  Image Type:   ARM Linux Kernel Image (uncompressed)
  Data Size:    26472 Bytes = 25.85 kB = 0.03 MB
  Load Address: 80208000
  Entry Point:  80208000
    Image arch/arm/boot/uImage is ready
    MODPOST 192 modules
    AS      arch/arm/boot/compressed/piggy.gzip.o
    LD      arch/arm/boot/compressed/vmlinux
    OBJCOPY arch/arm/boot/zImage
    Kernel: arch/arm/boot/zImage is ready
  $ ls -l arch/arm/boot/*Image
  -rwxrwxr-x 1 masahiro masahiro 13766656 Aug  8 23:23 arch/arm/boot/Image
  -rw-rw-r-- 1 masahiro masahiro    26536 Aug  8 23:23 arch/arm/boot/uImage
  -rwxrwxr-x 1 masahiro masahiro  6138648 Aug  8 23:23 arch/arm/boot/zImage

Please notice the uImage is extremely small when this issue is
encountered.  Besides, "Kernel: arch/arm/boot/zImage is ready" is
displayed twice, before and after the uImage log.

The root cause of this is the race condition between zImage and
uImage.  Actually, uImage depends on zImage, but the dependency
between the two is only described in arch/arm/boot/Makefile.
Because arch/arm/boot/Makefile is not included from the top-level
Makefile, it cannot know the dependency between zImage and uImage.

Consequently, when we run make with the parallel option, Kbuild
updates vmlinux first, and then two different threads descends into
the arch/arm/boot/Makefile almost at the same time, one for updating
zImage and the other for uImage.  While one thread is re-generating
zImage, the other also tries to update zImage before creating uImage
on top of that.  zImage is overwritten by the slower thread and then
uImage is created based on the half-written zImage.

This is the reason why "Kernel: arch/arm/boot/zImage is ready" is
displayed twice, and a broken uImage is created.

The same problem could happen on bootpImage.

This commit adds dependencies among Image, zImage, uImage, and
bootpImage to arch/arm/Makefile, which is included from the
top-level Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The mmap semaphore should not be taken when page faults are disabled.
Since pagefault_disable() no longer disables preemption, we now need
to use faulthandler_disabled() in place of in_atomic().
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Tested-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Rathe rthan directly accessing architecture internal functions, provide
an "method"-centric wrapper for qcom_scm-32 to do what's necessary to
ensure that the secure monitor can see the data.  This is called
"secure_flush_area" and ensures that the specified memory area is
coherent across the secure boundary.
Acked-by: Andy Gross <agross@codeaurora.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Since 906c5557 ("timekeeping: Copy the shadow-timekeeper over the
real timekeeper last") it has become possible on ARM to:

- Obtain a CLOCK_MONOTONIC_COARSE or CLOCK_REALTIME_COARSE timestamp
  via syscall.
- Subsequently obtain a timestamp for the same clock ID via VDSO which
  predates the first timestamp (by one jiffy).

This is because ARM's update_vsyscall is deriving the coarse time
using the __current_kernel_time interface, when it should really be
using the timekeeper object provided to it by the timekeeping core.
It happened to work before only because __current_kernel_time would
access the same timekeeper object which had been passed to
update_vsyscall.  This is no longer the case.

Cc: stable@vger.kernel.org
Fixes: 906c5557 ("timekeeping: Copy the shadow-timekeeper over the real timekeeper last")
Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

ret_fast_syscall runs when user space makes a syscall. However it
needs to be marked as such so the ELF information is correct. Before
it was:

   101: 8000f300     0 NOTYPE  LOCAL  DEFAULT    2 ret_fast_syscall

But with this change it correctly shows as:

   101: 8000f300    96 FUNC    LOCAL  DEFAULT    2 ret_fast_syscall

I see this function when using perf to unwind call stacks from kernel
space to user space. Without this change I would need to add some
special case logic when using the vmlinux ELF information.
Signed-off-by: Drew Richardson <drew.richardson@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Since the commit "b2c3e38a ARM: redo TTBR setup code for LPAE",
the setup code had been reworked. As a result the secondary CPUs
failed to come online in Big Endian.

As explained by Russell, the new code expected the value in r4/r5 to
be the least significant 32bits in r4 and the most significant 32bits
in r5. However, in the secondary code, we load this using ldrd, which
on BE reverses that.

This patch swap r4/r5 after the ldrd. It is done using the xor
instructions in order to not use a temporary register.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

This patch allows the use of CMA for DMA coherent memory allocation.
At the moment if the input parameter "is_coherent" is set to true
the allocation is not made using the CMA, which I think is not the
desired behaviour.
The patch covers the allocation and free of memory for coherent
DMA.
Signed-off-by: Lorenzo Nava <lorenx4@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The dmac_* functions are private to the ARM DMA API implementation, and
should not be used by drivers.  In order to discourage their use, remove
their prototypes and macros from asm/*.h.

We have to leave dmac_flush_range() behind as Exynos and MSM IOMMU code
use these; once these sites are fixed, this can be moved also.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Fold finish_arch_switch() into switch_to(), in preparation for the
removal of the finish_arch_switch call from core sched code.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Writes to /sys/.../cpuX/online fail if we determine the platform
doesn't support hotplug for that CPU. Furthermore, if the cpu_die
op isn't specified the system hangs when we try to offline a CPU
and it comes right back online unexpectedly. Let's figure this
stuff out before we make the sysfs nodes so that the online file
doesn't even exist if it isn't (at least sometimes) possible to
hotplug the CPU.

Add a new 'cpu_can_disable' op and repoint all 'cpu_disable'
implementations at it because all implementers use the op to
indicate if a CPU can be hotplugged or not in a static fashion.
With PSCI we may need to add a 'cpu_disable' op so that the
secure OS can be migrated off the CPU we're trying to hotplug.
In this case, the 'cpu_can_disable' op will indicate that all
CPUs are hotpluggable by returning true, but the 'cpu_disable' op
will make a PSCI migration call and occasionally fail, denying
the hotplug of a CPU. This shouldn't be any worse than x86 where
we may indicate that all CPUs are hotpluggable but occasionally
we can't offline a CPU due to check_irq_vectors_for_cpu_disable()
failing to find a CPU to move vectors to.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Nicolas Pitre <nico@linaro.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Acked-by: Simon Horman <horms@verge.net.au> [shmobile portion]
Tested-by: Simon Horman <horms@verge.net.au>
Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: <linux-sh@vger.kernel.org>
Tested-by: Tyler Baker <tyler.baker@linaro.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The Sourcery CodeBench Lite 2014.05 toolchain (gcc 4.8.3, binutils
2.24.51) has a GCC which implements -fuse-ld, and it doesn't include
the gold linker, but it lacks an ld.bfd executable in its
installation.  This means that passing -fuse-ld=bfd fails with:

      VDSO    arch/arm/vdso/vdso.so.raw
    collect2: fatal error: cannot find 'ld'

Arguably this is a deficiency in the toolchain, but I suspect it's
commonly used enough that it's worth accommodating: just use

cc-ldoption (to cause a link attempt) instead of cc-option to test
whether we can use -fuse-ld.  So -fuse-ld=bfd won't be used with this
toolchain, but the build will rightly succeed, just as it does for
toolchains which don't implement -fuse-ld (and don't use gold as the
default linker).

Note: this will change the failure mode for a corner case I was trying
to handle in d2b30cd4, where the toolchain defaults to the gold
linker and the BFD linker is not found in PATH, from:

      VDSO    arch/arm/vdso/vdso.so.raw
    collect2: fatal error: cannot find 'ld'

i.e. the BFD linker is not found, to:

      OBJCOPY arch/arm/vdso/vdso.so
    BFD: arch/arm/vdso/vdso.so: Not enough room for program headers, try
    linking with -N

that is, we fail to prevent gold from being used as the linker, and it
produces an object that objcopy can't digest.
Reported-by: Baruch Siach <baruch@tkos.co.il>
Tested-by: Baruch Siach <baruch@tkos.co.il>
Tested-by: Raphaël Poggi <poggi.raph@gmail.com>
Fixes: d2b30cd4 ("ARM: 8384/1: VDSO: force use of BFD linker")
Cc: stable@vger.kernel.org
Signed-off-by: Nathan Lynch <nathan_lynch@mentor.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Restore the OMAP4 barrier behaviour using the new implementation which
allows multiplatform systems to hook into the mb() and wmb() ARM
implementations to perform any necessary additional barrier maintanence.
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

This reverts commit 606da482.

We actually need this code for proper behaviour of OMAP4, and it needs
fixing a different way other than just removing the code.  Disabling
code which is necessary in the hopes of persuing multiplatform kernels
is a stupid approach.
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Add an extension to the heavy barrier code to allow a SoC specific
memory barrier function to be provided.  This is needed for platforms
where the interconnect has weak ordering, and thus needs assistance
to ensure that memory writes are properly visible in the correct order
to other parts of the system.
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

The existing memory barrier macro causes a significant amount of code
to be inserted inline at every call site.  For example, in
gpio_set_irq_type(), we have this for mb():

c0344c08:       f57ff04e        dsb     st
c0344c0c:       e59f8190        ldr     r8, [pc, #400]  ; c0344da4 <gpio_set_irq_type+0x230>
c0344c10:       e3590004        cmp     r9, #4
c0344c14:       e5983014        ldr     r3, [r8, #20]
c0344c18:       0a000054        beq     c0344d70 <gpio_set_irq_type+0x1fc>
c0344c1c:       e3530000        cmp     r3, #0
c0344c20:       0a000004        beq     c0344c38 <gpio_set_irq_type+0xc4>
c0344c24:       e50b2030        str     r2, [fp, #-48]  ; 0xffffffd0
c0344c28:       e50bc034        str     ip, [fp, #-52]  ; 0xffffffcc
c0344c2c:       e12fff33        blx     r3
c0344c30:       e51bc034        ldr     ip, [fp, #-52]  ; 0xffffffcc
c0344c34:       e51b2030        ldr     r2, [fp, #-48]  ; 0xffffffd0
c0344c38:       e5963004        ldr     r3, [r6, #4]

Moving the outer_cache_sync() call out of line reduces the impact of
the barrier:

c0344968:       f57ff04e        dsb     st
c034496c:       e35a0004        cmp     sl, #4
c0344970:       e50b2030        str     r2, [fp, #-48]  ; 0xffffffd0
c0344974:       0a000044        beq     c0344a8c <gpio_set_irq_type+0x1b8>
c0344978:       ebf363dd        bl      c001d8f4 <arm_heavy_mb>
c034497c:       e5953004        ldr     r3, [r5, #4]

This should reduce the cache footprint of this code.  Overall, this
results in a reduction of around 20K in the kernel size:

    text    data      bss      dec     hex filename
10773970  667392 10369656 21811018 14ccf4a ../build/imx6/vmlinux-old
10754219  667392 10369656 21791267 14c8223 ../build/imx6/vmlinux-new

Another advantage to this approach is that we can finally resolve the
issue of SoCs which have their own memory barrier requirements within
multiplatform kernels (such as OMAP.)  Here, the bus interconnects
need additional handling to ensure that writes become visible in the
correct order (eg, between dma_map() operations, writes to DMA
coherent memory, and MMIO accesses.)
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Richard Woodruff <r-woodruff2@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Fengguang Wu reports that building ARM with !MMU results in the
following build error:

   arch/arm/kernel/built-in.o: In function `__soft_restart':
>> :(.text+0x1624): undefined reference to `arch_virt_to_idmap'

Fix this by adding an appropriate IS_ENABLED(CONFIG_MMU) into the
__virt_to_idmap() inline function.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

We must invalidate the L1 cache before enabling coherency, otherwise
secondary CPUs can inject invalid cache lines into the coherent CPU
cluster, which could then be migrated to other CPUs.  This fixes a
recent regression with SoCFPGA randomly failing to boot.

Fixes: 02b4e275 ("ARM: v7 setup function should invalidate L1 cache")
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

nr_bitmaps member of mapping structure stores the number of already
allocated bitmaps and it is interpreted as loop iterator (it starts from
0 not from 1), so a comparison against number of possible bitmap
extensions should include this fact. This patch fixes this by changing
the extension failure condition. This issue has been introduced by
commit 4d852ef8 ("arm: dma-mapping: Add
support to extend DMA IOMMU mappings").
Reported-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Hyungwon Hwang <human.hwang@samsung.com>
Cc: stable@vger.kernel.org  # v3.15+
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

It's possible, albeit unlikely, that using the of_node here will
reference freed memory. Call of_node_put() after printing the
name to be safe.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>