Apple's EFI drivers supply device properties which are needed to support
Macs optimally. They contain vital information which cannot be obtained
any other way (e.g. Thunderbolt Device ROM). They're also used to convey
the current device state so that OS drivers can pick up where EFI
drivers left (e.g. GPU mode setting).

There's an EFI driver dubbed "AAPL,PathProperties" which implements a
per-device key/value store. Other EFI drivers populate it using a custom
protocol. The macOS bootloader /System/Library/CoreServices/boot.efi
retrieves the properties with the same protocol. The kernel extension
AppleACPIPlatform.kext subsequently merges them into the I/O Kit
registry (see ioreg(8)) where they can be queried by other kernel
extensions and user space.

This commit extends the efistub to retrieve the device properties before
ExitBootServices is called. It assigns them to devices in an fs_initcall
so that they can be queried with the API in <linux/property.h>.

Note that the device properties will only be available if the kernel is
booted with the efistub. Distros should adjust their installers to
always use the efistub on Macs. grub with the "linux" directive will not
work unless the functionality of this commit is duplicated in grub.
(The "linuxefi" directive should work but is not included upstream as of
this writing.)

The custom protocol has GUID 91BD12FE-F6C3-44FB-A5B7-5122AB303AE0 and
looks like this:

typedef struct {
	unsigned long version; /* 0x10000 */
	efi_status_t (*get) (
		IN	struct apple_properties_protocol *this,
		IN	struct efi_dev_path *device,
		IN	efi_char16_t *property_name,
		OUT	void *buffer,
		IN OUT	u32 *buffer_len);
		/* EFI_SUCCESS, EFI_NOT_FOUND, EFI_BUFFER_TOO_SMALL */
	efi_status_t (*set) (
		IN	struct apple_properties_protocol *this,
		IN	struct efi_dev_path *device,
		IN	efi_char16_t *property_name,
		IN	void *property_value,
		IN	u32 property_value_len);
		/* allocates copies of property name and value */
		/* EFI_SUCCESS, EFI_OUT_OF_RESOURCES */
	efi_status_t (*del) (
		IN	struct apple_properties_protocol *this,
		IN	struct efi_dev_path *device,
		IN	efi_char16_t *property_name);
		/* EFI_SUCCESS, EFI_NOT_FOUND */
	efi_status_t (*get_all) (
		IN	struct apple_properties_protocol *this,
		OUT	void *buffer,
		IN OUT	u32 *buffer_len);
		/* EFI_SUCCESS, EFI_BUFFER_TOO_SMALL */
} apple_properties_protocol;

Thanks to Pedro Vilaça for this blog post which was helpful in reverse
engineering Apple's EFI drivers and bootloader:
https://reverse.put.as/2016/06/25/apple-efi-firmware-passwords-and-the-scbo-myth/

If someone at Apple is reading this, please note there's a memory leak
in your implementation of the del() function as the property struct is
freed but the name and value allocations are not.

Neither the macOS bootloader nor Apple's EFI drivers check the protocol
version, but we do to avoid breakage if it's ever changed. It's been the
same since at least OS X 10.6 (2009).

The get_all() function conveniently fills a buffer with all properties
in marshalled form which can be passed to the kernel as a setup_data
payload. The number of device properties is dynamic and can change
between a first invocation of get_all() (to determine the buffer size)
and a second invocation (to retrieve the actual buffer), hence the
peculiar loop which does not finish until the buffer size settles.
The macOS bootloader does the same.

The setup_data payload is later on unmarshalled in an fs_initcall. The
idea is that most buses instantiate devices in "subsys" initcall level
and drivers are usually bound to these devices in "device" initcall
level, so we assign the properties in-between, i.e. in "fs" initcall
level.

This assumes that devices to which properties pertain are instantiated
from a "subsys" initcall or earlier. That should always be the case
since on macOS, AppleACPIPlatformExpert::matchEFIDevicePath() only
supports ACPI and PCI nodes and we've fully scanned those buses during
"subsys" initcall level.

The second assumption is that properties are only needed from a "device"
initcall or later. Seems reasonable to me, but should this ever not work
out, an alternative approach would be to store the property sets e.g. in
a btree early during boot. Then whenever device_add() is called, an EFI
Device Path would have to be constructed for the newly added device,
and looked up in the btree. That way, the property set could be assigned
to the device immediately on instantiation. And this would also work for
devices instantiated in a deferred fashion. It seems like this approach
would be more complicated and require more code. That doesn't seem
justified without a specific use case.

For comparison, the strategy on macOS is to assign properties to objects
in the ACPI namespace (AppleACPIPlatformExpert::mergeEFIProperties()).
That approach is definitely wrong as it fails for devices not present in
the namespace: The NHI EFI driver supplies properties for attached
Thunderbolt devices, yet on Macs with Thunderbolt 1 only one device
level behind the host controller is described in the namespace.
Consequently macOS cannot assign properties for chained devices. With
Thunderbolt 2 they started to describe three device levels behind host
controllers in the namespace but this grossly inflates the SSDT and
still fails if the user daisy-chained more than three devices.

We copy the property names and values from the setup_data payload to
swappable virtual memory and afterwards make the payload available to
the page allocator. This is just for the sake of good housekeeping, it
wouldn't occupy a meaningful amount of physical memory (4444 bytes on my
machine). Only the payload is freed, not the setup_data header since
otherwise we'd break the list linkage and we cannot safely update the
predecessor's ->next link because there's no locking for the list.

The payload is currently not passed on to kexec'ed kernels, same for PCI
ROMs retrieved by setup_efi_pci(). This can be added later if there is
demand by amending setup_efi_state(). The payload can then no longer be
made available to the page allocator of course.

Tested-by: Lukas Wunner <lukas@wunner.de> [MacBookPro9,1]
Tested-by: Pierre Moreau <pierre.morrow@free.fr> [MacBookPro11,3]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andreas Noever <andreas.noever@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Pedro Vilaça <reverser@put.as>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: grub-devel@gnu.org
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-9-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

We already have a macro to invoke boot services which on x86 adapts
automatically to the bitness of the EFI firmware:  efi_call_early().

The macro allows sharing of functions across arches and bitness variants
as long as those functions only call boot services.  However in practice
functions in the EFI stub contain a mix of boot services calls and
protocol calls.

Add an efi_call_proto() macro for bitness-agnostic protocol calls to
allow sharing more code across arches as well as deduplicating 32 bit
and 64 bit code paths.

On x86, implement it using a new efi_table_attr() macro for bitness-
agnostic table lookups.  Refactor efi_call_early() to make use of the
same macro.  (The resulting object code remains identical.)
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andreas Noever <andreas.noever@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-8-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

We're about to extended the efistub to retrieve device properties from
EFI on Apple Macs. The properties use EFI Device Paths to indicate the
device they belong to. This commit adds a parser which, given an EFI
Device Path, locates the corresponding struct device and returns a
reference to it.

Initially only ACPI and PCI Device Path nodes are supported, these are
the only types needed for Apple device properties (the corresponding
macOS function AppleACPIPlatformExpert::matchEFIDevicePath() does not
support any others). Further node types can be added with little to
moderate effort.

Apple device properties is currently the only use case of this parser,
but Peter Jones intends to use it to match up devices with the
ConInDev/ConOutDev/ErrOutDev variables and add sysfs attributes to these
devices to say the hardware supports using them as console. Thus,
make this parser a separate component which can be selected with config
option EFI_DEV_PATH_PARSER. It can in principle be compiled as a module
if acpi_get_first_physical_node() and acpi_bus_type are exported (and
efi_get_device_by_path() itself is exported).

The dependency on CONFIG_ACPI is needed for acpi_match_device_ids().
It can be removed if an empty inline stub is added for that function.
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Andreas Noever <andreas.noever@gmail.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-7-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Invoke the EFI_RNG_PROTOCOL protocol in the context of the stub and
install the Linux-specific RNG seed UEFI config table. This will be
picked up by the EFI routines in the core kernel to seed the kernel
entropy pool.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-6-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Make random.c build for ARM by moving the fallback definition of
EFI_ALLOC_ALIGN to efistub.h, and replacing a division by a value
we know to be a power of 2 with a right shift (this is required since
ARM does not have any integer division helper routines in its decompressor)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-5-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Specify a Linux specific UEFI configuration table that carries some
random bits, and use the contents during early boot to seed the kernel's
random number generator. This allows much strong random numbers to be
generated early on.

The entropy is fed to the kernel using add_device_randomness(), which is
documented as being appropriate for being called very early.

Since UEFI configuration tables may also be consumed by kexec'd kernels,
register a reboot notifier that updates the seed in the table.

Note that the config table could be generated by the EFI stub or by any
other UEFI driver or application (e.g., GRUB), but the random seed table
GUID and the associated functionality should be considered an internal
kernel interface (unless it is promoted to ABI later on)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-4-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Since I will be co-maintaining the EFI subsystem, it makes sense to
mention the ARM and arm64 EFI bits in the EFI section in MAINTAINERS
so that Matt, the list and I get cc'ed on proposed changes.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Will Deacon <will.deacon@arm.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: M: Matthew Garrett <matthew.garrett@nebula.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-3-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Adjust the size used in calculations to match the actual size of allocation
that will be performed based on EFI size/alignment constraints.
efi_high_alloc() and efi_low_alloc() use the passed size in bytes directly
to find space in the memory map for the allocation, rather than the actual
allocation size that has been adjusted for size and alignment constraints.
This results in failed allocations and retries in efi_high_alloc().  The
same error is present in efi_low_alloc(), although failure will only happen
if the lowest memory block is small.
Also use EFI_PAGE_SIZE consistently and remove use of EFI_PAGE_SHIFT to
calculate page size.
Signed-off-by: Roy Franz <roy.franz@hpe.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20161112213237.8804-2-matt@codeblueprint.co.ukSigned-off-by: Ingo Molnar <mingo@kernel.org>

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Pull ACPI fix from Rafael Wysocki:
 "Fix a recent regression in the 8250_dw serial driver introduced by
  adding a quirk for the APM X-Gene SoC to it which uncovered an issue
  related to the handling of built-in device properties in the core ACPI
  device enumeration code (Heikki Krogerus)"

* tag 'acpi-4.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI / platform: Add support for build-in properties

Pull power management fixes from Rafael Wysocki:
 "These fix two bugs in error code paths in the PM core (system-wide
  suspend of devices), a device reference leak in the boot-time suspend
  test code and a cpupower utility regression from the 4.7 cycle.

  Specifics:

   - Prevent the PM core from attempting to suspend parent devices if
     any of their children, whose suspend callbacks were invoked
     asynchronously, have failed to suspend during the "late" and
     "noirq" phases of system-wide suspend of devices (Brian Norris).

   - Prevent the boot-time system suspend test code from leaking a
     reference to the RTC device used by it (Johan Hovold).

   - Fix cpupower to use the return value of one of its library
     functions correctly and restore the correct behavior of it when
     used for setting cpufreq tunables broken during the 4.7 development
     cycle (Laura Abbott)"

* tag 'pm-4.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / sleep: don't suspend parent when async child suspend_{noirq, late} fails
  PM / sleep: fix device reference leak in test_suspend
  cpupower: Correct return type of cpu_power_is_cpu_online() in cpufreq-set

Pull ARC fixes from Vineet Gupta:

 - mmap handler for dma ops as generic handler no longer works for us
   [Alexey]

 - Fixes for EZChip platform [Noam]

 - Fix RTC clocksource driver build issue

 - ARC IRQ handling fixes [Yuriy]

 - Revert a recent makefile change which doesn't go well with oldish
   tools out in the wild

* tag 'arc-4.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARCv2: MCIP: Use IDU_M_DISTRI_DEST mode if there is only 1 destination core
  ARC: IRQ: Do not use hwirq as virq and vice versa
  ARC: [plat-eznps] set default baud for early console
  ARC: [plat-eznps] remove IPI clear from SMP operations
  Revert "ARC: build: retire old toggles"
  ARC: timer: rtc: implement read loop in "C" vs. inline asm
  ARC: change return value of userspace cmpxchg assist syscall
  arc: Implement arch-specific dma_map_ops.mmap
  ARC: [SMP] avoid overriding present cpumask
  ARC: Enable PERF_EVENTS in nSIM driven platforms

Merge tag 'platform-drivers-x86-v4.9-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver fixes from Darren Hart:
 "Minor doc fix, a DMI match for ideapad and a fix to toshiba-wmi to
  avoid loading on non-toshiba systems.

  Documentation/ABI:
   - ibm_rtl: The "What:" fields are incomplete

  toshiba-wmi:
   - Fix loading the driver on non Toshiba laptops

  ideapad-laptop:
   - Add another DMI entry for Yoga 900"

* tag 'platform-drivers-x86-v4.9-3' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86:
  Documentation/ABI: ibm_rtl: The "What:" fields are incomplete
  toshiba-wmi: Fix loading the driver on non Toshiba laptops
  ideapad-laptop: Add another DMI entry for Yoga 900

Pull block fixes from Jens Axboe:
 "Two small (really, one liners both of them!) fixes that should go into
  this series:

   - Request allocation error handling fix for nbd, from Christophe,
     fixing a regression in this series.

   - An oops fix for drbd. Not a regression in this series, but stable
     material. From Richard"

* 'for-linus' of git://git.kernel.dk/linux-block:
  drbd: Fix kernel_sendmsg() usage - potential NULL deref
  nbd: Fix error handling

Pull PCI fixes from Bjorn Helgaas:

 - Update MAINTAINERS for Intel VMD driver filename

 - Update Rockchip rk3399 host bridge driver DTS and resets

 - Fix ROM shadow problem that made some video device initialization
   fail

* tag 'pci-v4.9-fixes-3' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci:
  PCI: VMD: Update filename to reflect move
  arm64: dts: rockchip: add three new resets for rk3399 PCIe controller
  PCI: rockchip: Add three new resets as required properties
  PCI: Don't attempt to claim shadow copies of ROM

Pull drm fixes from Dave Airlie:
 "AMD, radeon, i915, imx, msm and udl fixes:

   - amdgpu/radeon have a number of power management regressions and
     fixes along with some better error checking

   - imx has a single regression fix

   - udl has a single kmalloc instead of stack for usb control msg fix

   - msm has some fixes for modesetting bugs and regressions

   - i915 has a one fix for a Sandybridge regression along with some
     others for DP audio.

  They all seem pretty okay at this stage, we've got one MST fix I know
  going through process for i915, but I expect it'll be next week"

* tag 'drm-fixes-for-v4.9-rc5' of git://people.freedesktop.org/~airlied/linux: (30 commits)
  drm/udl: make control msg static const. (v2)
  drm/amd/powerplay: implement get_clock_by_type for iceland.
  drm/amd/powerplay/smu7: fix checks in smu7_get_evv_voltages (v2)
  drm/amd/powerplay: update phm_get_voltage_evv_on_sclk for iceland
  drm/amd/powerplay: propagate errors in phm_get_voltage_evv_on_sclk
  drm/imx: disable planes before DC
  drm/amd/powerplay: return false instead of -EINVAL
  drm/amdgpu/powerplay/smu7: fix unintialized data usage
  drm/amdgpu: fix crash in acp_hw_fini
  drm/i915: Limit Valleyview and earlier to only using mappable scanout
  drm/i915: Round tile chunks up for constructing partial VMAs
  drm/i915/dp: Extend BDW DP audio workaround to GEN9 platforms
  drm/i915/dp: BDW cdclk fix for DP audio
  drm/i915/vlv: Prevent enabling hpd polling in late suspend
  drm/i915: Respect alternate_ddc_pin for all DDI ports
  drm/msm: Fix error handling crashes seen when VRAM allocation fails
  drm/msm/mdp5: 8x16 actually has 8 mixer stages
  drm/msm/mdp5: no scaling support on RGBn pipes for 8x16
  drm/msm/mdp5: handle non-fullscreen base plane case
  drm/msm: Set CLK_IGNORE_UNUSED flag for PLL clocks
  ...

Pull MMC fixes from Ulf Hansson:
 "MMC core:
   - Fix mmc card initialization for hosts not supporting HW busy
     detection
   - Fix mmc_test for sending commands during non-blocking write

  MMC host:
   - mxs: Avoid using an uninitialized
   - sdhci: Restore enhanced strobe setting during runtime resume
   - sdhci: Fix a couple of reset related issues
   - dw_mmc: Fix a reset controller issue"

* tag 'mmc-v4.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: mxs: Initialize the spinlock prior to using it
  mmc: mmc: Use 500ms as the default generic CMD6 timeout
  mmc: mmc_test: Fix "Commands during non-blocking write" tests
  mmc: sdhci: Fix missing enhanced strobe setting during runtime resume
  mmc: sdhci: Reset cmd and data circuits after tuning failure
  mmc: sdhci: Fix unexpected data interrupt handling
  mmc: sdhci: Fix CMD line reset interfering with ongoing data transfer
  mmc: dw_mmc: add the "reset" as name of reset controller
  Documentation: synopsys-dw-mshc: add binding for reset-names

Pull pin control fixes from Linus Walleij:
 "All is about drivers, no core business going on.

   - Fix a host of runtime problems with the Intel Cherryview driver:
     suspend/resume needs to be marshalled properly, and strange effects
     from BIOS interaction during suspend/resume need to be dealt with.

   - A single bit was being set wrong in the Aspeed driver.

   - Fix an iProc probe ordering fallout resulting from v4.9
     refactorings for bus population.

   - Do not specify a default trigger in the ST Micro cascaded GPIO IRQ
     controller: the kernel will moan.

   - Make IRQs optional altogether on the STM32 driver, it turns out not
     all systems have them or want them.

   - Fix a re-probe bug in the i.MX driver, it will eventually crash if
     probed repeatedly, not good"

* tag 'pinctrl-v4.9-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl-aspeed-g5: Never set SCU90[6]
  pinctrl: cherryview: Prevent possible interrupt storm on resume
  pinctrl: cherryview: Serialize register access in suspend/resume
  pinctrl: imx: reset group index on probe
  pinctrl: stm32: move gpio irqs binding to optional
  pinctrl: stm32: remove dependency with interrupt controller
  pinctrl: st: don't specify default interrupt trigger
  pinctrl: iproc: Fix iProc and NSP GPIO support

* pm-tools-fixes:
  cpupower: Correct return type of cpu_power_is_cpu_online() in cpufreq-set

* pm-sleep-fixes:
  PM / sleep: don't suspend parent when async child suspend_{noirq, late} fails
  PM / sleep: fix device reference leak in test_suspend

* device-properties:
  ACPI / platform: Add support for build-in properties

Merge fixes for -Wmaybe-uninitialized from Arnd Bergmann:
 "It took a while for some patches to make it into mainline through
  maintainer trees, but the 28-patch series is now reduced to 10, with
  one tiny patch added at the end.

  Aside from patches that are no longer required, I did these changes
  compared to version 1:

   - Dropped "iio: maxim_thermocouple: detect invalid storage size in
     read()", which is currently in linux-next as commit 32cb7d27.
     This is the only remaining warning I see for a couple of corner
     cases (kbuild bot reports it on blackfin, kernelci bot and arm-soc
     bot both report it on arm64)

   - Dropped "brcmfmac: avoid maybe-uninitialized warning in
     brcmf_cfg80211_start_ap", which is currently in net/master merge
     pending.

   - Dropped two x86 patches, "x86: math-emu: possible uninitialized
     variable use" and "x86: mark target address as output in 'insb'
     asm" as they do not seem to trigger for a default build, and I got
     no feedback on them. Both of these are ancient issues and seem
     harmless, I will send them again to the x86 maintainers once the
     rest is merged.

   - Dropped "rbd: false-postive gcc-4.9 -Wmaybe-uninitialized" based on
     feedback from Ilya Dryomov, who already has a different fix queued
     up for v4.10. The kbuild bot reports this as a warning for xtensa.

   - Replaced "crypto: aesni: avoid -Wmaybe-uninitialized warning" with
     a simpler patch, this one always triggers but my first solution
     would not be safe for linux-4.9 any more at this point. I'll follow
     up with the larger patch as a cleanup for 4.10.

   - Replaced "dib0700: fix nec repeat handling" with a better one,
     contributed by Sean Young"

* -Wmaybe-uninitialized fixes:
  Kbuild: enable -Wmaybe-uninitialized warnings by default
  pcmcia: fix return value of soc_pcmcia_regulator_set
  infiniband: shut up a maybe-uninitialized warning
  crypto: aesni: shut up -Wmaybe-uninitialized warning
  rc: print correct variable for z8f0811
  dib0700: fix nec repeat handling
  s390: pci: don't print uninitialized data for debugging
  nios2: fix timer initcall return value
  x86: apm: avoid uninitialized data
  NFSv4.1: work around -Wmaybe-uninitialized warning
  Kbuild: enable -Wmaybe-uninitialized warning for "make W=1"

Merge misc fixes from Andrew Morton:
 "15 fixes"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
  lib/stackdepot: export save/fetch stack for drivers
  mm: kmemleak: scan .data.ro_after_init
  memcg: prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB
  coredump: fix unfreezable coredumping task
  mm/filemap: don't allow partially uptodate page for pipes
  mm/hugetlb: fix huge page reservation leak in private mapping error paths
  ocfs2: fix not enough credit panic
  Revert "console: don't prefer first registered if DT specifies stdout-path"
  mm: hwpoison: fix thp split handling in memory_failure()
  swapfile: fix memory corruption via malformed swapfile
  mm/cma.c: check the max limit for cma allocation
  scripts/bloat-o-meter: fix SIGPIPE
  shmem: fix pageflags after swapping DMA32 object
  mm, frontswap: make sure allocated frontswap map is assigned
  mm: remove extra newline from allocation stall warning

Pull VFS fixes from Al Viro:
 "Christoph's and Jan's aio fixes, fixup for generic_file_splice_read
  (removal of pointless detritus that actually breaks it when used for
  gfs2 ->splice_read()) and fixup for generic_file_read_iter()
  interaction with ITER_PIPE destinations."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  splice: remove detritus from generic_file_splice_read()
  mm/filemap: don't allow partially uptodate page for pipes
  aio: fix freeze protection of aio writes
  fs: remove aio_run_iocb
  fs: remove the never implemented aio_fsync file operation
  aio: hold an extra file reference over AIO read/write operations

Pull Ceph fixes from Ilya Dryomov:
 "Ceph's ->read_iter() implementation is incompatible with the new
  generic_file_splice_read() code that went into -rc1.  Switch to the
  less efficient default_file_splice_read() for now; the proper fix is
  being held for 4.10.

  We also have a fix for a 4.8 regression and a trival libceph fixup"

* tag 'ceph-for-4.9-rc5' of git://github.com/ceph/ceph-client:
  libceph: initialize last_linger_id with a large integer
  libceph: fix legacy layout decode with pool 0
  ceph: use default file splice read callback

Pull NFS client bugfixes from Anna Schumaker:
 "Most of these fix regressions in 4.9, and none are going to stable
  this time around.

  Bugfixes:
   - Trim extra slashes in v4 nfs_paths to fix tools that use this
   - Fix a -Wmaybe-uninitialized warnings
   - Fix suspicious RCU usages
   - Fix Oops when mounting multiple servers at once
   - Suppress a false-positive pNFS error
   - Fix a DMAR failure in NFS over RDMA"

* tag 'nfs-for-4.9-3' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  xprtrdma: Fix DMAR failure in frwr_op_map() after reconnect
  fs/nfs: Fix used uninitialized warn in nfs4_slot_seqid_in_use()
  NFS: Don't print a pNFS error if we aren't using pNFS
  NFS: Ignore connections that have cl_rpcclient uninitialized
  SUNRPC: Fix suspicious RCU usage
  NFSv4.1: work around -Wmaybe-uninitialized warning
  NFS: Trim extra slash in v4 nfs_path

Merge tag 'xfs-fixes-for-linus-4.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs

Pull xfs fix from Dave Chinner:
 "This is a fix for an unmount hang (regression) when the filesystem is
  shutdown.  It was supposed to go to you for -rc3, but I accidentally
  tagged the commit prior to it in that pullreq.

  Summary:

   - fix for aborting deferred transactions on filesystem shutdown"

* tag 'xfs-fixes-for-linus-4.9-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
  xfs: defer should abort intent items if the trans roll fails

Previously the warnings were added back at the W=1 level and above, this
now turns them on again by default, assuming that we have addressed all
warnings and again have a clean build for v4.10.

I found a number of new warnings in linux-next already and submitted
bugfixes for those.  Hopefully they are caught by the 0day builder in
the future as soon as this patch is merged.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The newly introduced soc_pcmcia_regulator_set() function sometimes
returns without setting its return code, as shown by this warning:

  drivers/pcmcia/soc_common.c: In function 'soc_pcmcia_regulator_set':
  drivers/pcmcia/soc_common.c:112:5: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This changes it to propagate the regulator_disable() result instead.

Fixes: ac61b600 ("pcmcia: soc_common: add support for Vcc and Vpp regulators")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Some configurations produce this harmless warning when built with gcc
-Wmaybe-uninitialized:

  infiniband/core/cma.c: In function 'cma_get_net_dev':
  infiniband/core/cma.c:1242:12: warning: 'src_addr_storage.sin_addr.s_addr' may be used uninitialized in this function [-Wmaybe-uninitialized]

I previously reported this for the powerpc64 defconfig, but have now
reproduced the same thing for x86 as well, using gcc-5 or higher.

The code looks correct to me, and this change just rearranges it by
making sure we alway initialize the entire address structure to make the
warning disappear.  My first approach added an initialization at the
time of the declaration, which Doug commented may be too costly, so I
hope this version doesn't add overhead.

Link: http://arm-soc.lixom.net/buildlogs/mainline/v4.7-rc6/buildall.powerpc.ppc64_defconfig.log.passed
Link: https://patchwork.kernel.org/patch/9212825/Acked-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The rfc4106 encrypy/decrypt helper functions cause an annoying
false-positive warning in allmodconfig if we turn on
-Wmaybe-uninitialized warnings again:

  arch/x86/crypto/aesni-intel_glue.c: In function ‘helper_rfc4106_decrypt’:
  include/linux/scatterlist.h:67:31: warning: ‘dst_sg_walk.sg’ may be used uninitialized in this function [-Wmaybe-uninitialized]

The problem seems to be that the compiler doesn't track the state of the
'one_entry_in_sg' variable across the kernel_fpu_begin/kernel_fpu_end
section.

This takes the easy way out by adding a bogus initialization, which
should be harmless enough to get the patch into v4.9 so we can turn on
this warning again by default without producing useless output.  A
follow-up patch for v4.10 rearranges the code to make the warning go
away.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A recent rework accidentally left a debugging printk untouched while
changing the meaning of the variables, leading to an uninitialized
variable being printed:

  drivers/media/i2c/ir-kbd-i2c.c: In function 'get_key_haup_common':
  drivers/media/i2c/ir-kbd-i2c.c:62:2: error: 'toggle' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This prints the correct one instead, as we did before the patch.

Fixes: 00bb8207 ("[media] rc: Hauppauge z8f0811 can decode RC6")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When receiving a nec repeat, ensure the correct scancode is repeated
rather than a random value from the stack.  This removes the need for
the bogus uninitialized_var() and also fixes the warnings:

    drivers/media/usb/dvb-usb/dib0700_core.c: In function ‘dib0700_rc_urb_completion’:
    drivers/media/usb/dvb-usb/dib0700_core.c:679: warning: ‘protocol’ may be used uninitialized in this function

[sean addon: So after writing the patch and submitting it, I've bought the
             hardware on ebay. Without this patch you get random scancodes
             on nec repeats, which the patch indeed fixes.]
Signed-off-by: Sean Young <sean@mess.org>
Tested-by: Sean Young <sean@mess.org>
Cc: stable@vger.kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

gcc correctly warns about an incorrect use of the 'pa' variable in case
we pass an empty scatterlist to __s390_dma_map_sg:

  arch/s390/pci/pci_dma.c: In function '__s390_dma_map_sg':
  arch/s390/pci/pci_dma.c:309:13: warning: 'pa' may be used uninitialized in this function [-Wmaybe-uninitialized]

This adds a bogus initialization to the function to sanitize the debug
output.  I would have preferred a solution without the initialization,
but I only got the report from the kbuild bot after turning on the
warning again, and didn't manage to reproduce it myself.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

When called more than twice, the nios2_time_init() function return an
uninitialized value, as detected by gcc -Wmaybe-uninitialized

  arch/nios2/kernel/time.c: warning: 'ret' may be used uninitialized in this function

This makes it return '0' here, matching the comment above the function.
Acked-by: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

apm_bios_call() can fail, and return a status in its argument structure.
If that status however is zero during a call from
apm_get_power_status(), we end up using data that may have never been
set, as reported by "gcc -Wmaybe-uninitialized":

  arch/x86/kernel/apm_32.c: In function ‘apm’:
  arch/x86/kernel/apm_32.c:1729:17: error: ‘bx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  arch/x86/kernel/apm_32.c:1835:5: error: ‘cx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  arch/x86/kernel/apm_32.c:1730:17: note: ‘cx’ was declared here
  arch/x86/kernel/apm_32.c:1842:27: error: ‘dx’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
  arch/x86/kernel/apm_32.c:1731:17: note: ‘dx’ was declared here

This changes the function to return "APM_NO_ERROR" here, which makes the
code more robust to broken BIOS versions, and avoids the warning.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

A bugfix introduced a harmless gcc warning in nfs4_slot_seqid_in_use if
we enable -Wmaybe-uninitialized again:

  fs/nfs/nfs4session.c:203:54: error: 'cur_seq' may be used uninitialized in this function [-Werror=maybe-uninitialized]

gcc is not smart enough to conclude that the IS_ERR/PTR_ERR pair results
in a nonzero return value here.  Using PTR_ERR_OR_ZERO() instead makes
this clear to the compiler.

Fixes: e09c978a ("NFSv4.1: Fix Oopsable condition in server callback races")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Traditionally, we have always had warnings about uninitialized variables
enabled, as this is part of -Wall, and generally a good idea [1], but it
also always produced false positives, mainly because this is a variation
of the halting problem and provably impossible to get right in all cases
[2].

Various people have identified cases that are particularly bad for false
positives, and in commit e74fc973 ("Turn off -Wmaybe-uninitialized
when building with -Os"), I turned off the warning for any build that
was done with CC_OPTIMIZE_FOR_SIZE.  This drastically reduced the number
of false positive warnings in the default build but unfortunately had
the side effect of turning the warning off completely in 'allmodconfig'
builds, which in turn led to a lot of warnings (both actual bugs, and
remaining false positives) to go in unnoticed.

With commit 877417e6 ("Kbuild: change CC_OPTIMIZE_FOR_SIZE
definition") enabled the warning again for allmodconfig builds in v4.7
and in v4.8-rc1, I had finally managed to address all warnings I get in
an ARM allmodconfig build and most other maybe-uninitialized warnings
for ARM randconfig builds.

However, commit 6e8d666e ("Disable "maybe-uninitialized" warning
globally") was merged at the same time and disabled it completely for
all configurations, because of false-positive warnings on x86 that I had
not addressed until then.  This caused a lot of actual bugs to get
merged into mainline, and I sent several dozen patches for these during
the v4.9 development cycle.  Most of these are actual bugs, some are for
correct code that is safe because it is only called under external
constraints that make it impossible to run into the case that gcc sees,
and in a few cases gcc is just stupid and finds something that can
obviously never happen.

I have now done a few thousand randconfig builds on x86 and collected
all patches that I needed to address every single warning I got (I can
provide the combined patch for the other warnings if anyone is
interested), so I hope we can get the warning back and let people catch
the actual bugs earlier.

This reverts the change to disable the warning completely and for now
brings it back at the "make W=1" level, so we can get it merged into
mainline without introducing false positives.  A follow-up patch enables
it on all levels unless some configuration option turns it off because
of false-positives.

Link: https://rusty.ozlabs.org/?p=232 [1]
Link: https://gcc.gnu.org/wiki/Better_Uninitialized_Warnings [2]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Some drivers would like to record stacktraces in order to aide leak
tracing.  As stackdepot already provides a facility for only storing the
unique traces, thereby reducing the memory required, export that
functionality for use by drivers.

The code was originally created for KASAN and moved under lib in commit
cd11016e ("mm, kasan: stackdepot implementation.  Enable stackdepot
for SLAB") so that it could be shared with mm/.  In turn, we want to
share it now with drivers.

Link: http://lkml.kernel.org/r/20161108133209.22704-1-chris@chris-wilson.co.ukSigned-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Limit the number of kmemleak false positives by including
.data.ro_after_init in memory scanning.  To achieve this we need to add
symbols for start and end of the section to the linker scripts.

The problem was been uncovered by commit 56989f6d ("genetlink: mark
families as __ro_after_init").

Link: http://lkml.kernel.org/r/1478274173-15218-1-git-send-email-jakub.kicinski@netronome.comReviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

While testing OBJFREELIST_SLAB integration with pagealloc, we found a
bug where kmem_cache(sys) would be created with both CFLGS_OFF_SLAB &
CFLGS_OBJFREELIST_SLAB.  When it happened, critical allocations needed
for loading drivers or creating new caches will fail.

The original kmem_cache is created early making OFF_SLAB not possible.
When kmem_cache(sys) is created, OFF_SLAB is possible and if pagealloc
is enabled it will try to enable it first under certain conditions.
Given kmem_cache(sys) reuses the original flag, you can have both flags
at the same time resulting in allocation failures and odd behaviors.

This fix discards allocator specific flags from memcg before calling
create_cache.

The bug exists since 4.6-rc1 and affects testing debug pagealloc
configurations.

Fixes: b03a017b ("mm/slab: introduce new slab management type, OBJFREELIST_SLAB")
Link: http://lkml.kernel.org/r/1478553075-120242-1-git-send-email-thgarnie@google.comSigned-off-by: Greg Thelen <gthelen@google.com>
Signed-off-by: Thomas Garnier <thgarnie@google.com>
Tested-by: Thomas Garnier <thgarnie@google.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>