Add a ubi_fastmap_close() to free all resources used by fastmap
at WL shutdown.
Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Guido Martínez <guido@vanguardiasur.com.ar>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

There is no need to allocate new ones every time, we can reuse
the existing ones.
This makes the code cleaner and more easy to follow.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Tanya Brokhman <tlinder@codeaurora.org>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

Currently ubi_refill_pools() first fills the first and then
the second one.
If only very few free PEBs are available the second pool can get
zero PEBs.
Change ubi_refill_pools() to distribute free PEBs fair between
all pools.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

Make it two functions, wl_get_wle() and wl_get_peb().
wl_get_peb() works exactly like __wl_get_peb() but wl_get_wle()
does not call produce_free_peb().
While refilling the fastmap user pool we cannot release ubi->wl_lock
as produce_free_peb() does.
Hence the fastmap logic uses now wl_get_wle().
Signed-off-by: Richard Weinberger <richard@nod.at>

ubi_wl_get_peb() has two problems, it reads the pool
size and usage counters without any protection.
While reading one value would be perfectly fine it reads multiple
values and compares them. This is racy and can lead to incorrect
pool handling.
Furthermore ubi_update_fastmap() is called without wl_lock held,
before incrementing the used counter it needs to be checked again.
It could happen that another thread consumed all PEBs from the
pool and the counter goes beyond ->size.
Signed-off-by: Richard Weinberger <richard@nod.at>

...otherwise the deferred work might run after datastructures
got freed and corrupt memory.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

If the WL pool runs out of PEBs we schedule a fastmap write
to refill it as soon as possible.
Ensure that only one at a time is scheduled otherwise we might end in
a fastmap write storm because writing the fastmap can schedule another
write if bitflips are detected.
Signed-off-by: Richard Weinberger <richard@nod.at>
Reviewed-by: Tanya Brokhman <tlinder@codeaurora.org>
Reviewed-by: Guido Martínez <guido@vanguardiasur.com.ar>

The kerneldoc for @vid_hdr_aloffset continues onto a second line, but
this is not obvious, because the second line isn't indented, and it
begins with '@'.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

The comparison from the previous line seems to have been erroneously
(partially) copied-and-pasted onto the next. The second line should be
checking req.bytes, not req.lnum.

Coverity CID #139400

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
[rw: Fixed comparison]
Signed-off-by: Richard Weinberger <richard@nod.at>

In some of the 'out_not_moved' error paths, lnum may be used
uninitialized. Don't ignore the warning; let's fix it.

This uninitialized variable doesn't have much visible effect in the end,
since we just schedule the PEB for erasure, and its LEB number doesn't
really matter (it just gets printed in debug messages). But let's get it
straight anyway.

Coverity CID #113449

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

If aeb->len >= vol->reserved_pebs, we should not be writing aeb into the
PEB->LEB mapping.

Caught by Coverity, CID #711212.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

We are completely discarding the earlier value of 'bitflips', which
could reflect a bitflip found in ubi_io_read_vid_hdr(). Let's use the
bitwise OR of header and data 'bitflip' statuses instead.

Coverity CID #1226856

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

In the case where we have more than one volumes on different UBI
devices, it may be not that easy to tell which volume prints the
messages.  Add ubi number and volume id in ubifs_msg/warn/error
to help debug. These two values are passed by struct ubifs_info.

For those where ubifs_info is not initialized yet, ubifs_* is
replaced by pr_*. For those where ubifs_info is not avaliable,
ubifs_info is passed to the calling function as a const parameter.

The output looks like,

[   95.444879] UBIFS (ubi0:1): background thread "ubifs_bgt0_1" started, PID 696
[   95.484688] UBIFS (ubi0:1): UBIFS: mounted UBI device 0, volume 1, name "test1"
[   95.484694] UBIFS (ubi0:1): LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[   95.484699] UBIFS (ubi0:1): FS size: 30220288 bytes (28 MiB, 238 LEBs), journal size 1523712 bytes (1 MiB, 12 LEBs)
[   95.484703] UBIFS (ubi0:1): reserved for root: 1427378 bytes (1393 KiB)
[   95.484709] UBIFS (ubi0:1): media format: w4/r0 (latest is w4/r0), UUID 40DFFC0E-70BE-4193-8905-F7D6DFE60B17, small LPT model
[   95.489875] UBIFS (ubi1:0): background thread "ubifs_bgt1_0" started, PID 699
[   95.529713] UBIFS (ubi1:0): UBIFS: mounted UBI device 1, volume 0, name "test2"
[   95.529718] UBIFS (ubi1:0): LEB size: 126976 bytes (124 KiB), min./max. I/O unit sizes: 2048 bytes/2048 bytes
[   95.529724] UBIFS (ubi1:0): FS size: 19808256 bytes (18 MiB, 156 LEBs), journal size 1015809 bytes (0 MiB, 8 LEBs)
[   95.529727] UBIFS (ubi1:0): reserved for root: 935592 bytes (913 KiB)
[   95.529733] UBIFS (ubi1:0): media format: w4/r0 (latest is w4/r0), UUID EEB7779D-F419-4CA9-811B-831CAC7233D4, small LPT model

[  954.264767] UBIFS error (ubi1:0 pid 756): ubifs_read_node: bad node type (255 but expected 6)
[  954.367030] UBIFS error (ubi1:0 pid 756): ubifs_read_node: bad node at LEB 0:0, LEB mapping status 1
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

Directly return recover_head() and ubifs_leb_unmap()
instead of storing value in err and testing it.
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

Change 'comress' to 'compress'
Change 'inteval' to 'interval'
Change 'disabe' to 'disable'
Change 'nenver' to 'never'
Signed-off-by: Yannick Guerrini <yguerrini@tomshardware.fr>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

The commits 781c5717 ("UBIFS: intialize LPT earlier") and 09801194 ("UBIFS:
fix-up free space earlier") move some initialization before marking the
master node dirty. But the modification changes the conditions of writing
master.

If unclean umount happens, ubifs may fail when mounting. But trying to
mount it will write new master nodes on the flash. This is useless but
increasing sqnum. So check need_recovery before writing master node, and
don't create new master node if filesystem needs recovery.

The behavour of the bug shows at:
http://lists.infradead.org/pipermail/linux-mtd/2015-February/057712.htmlSigned-off-by: Sheng Yong <shengyong1@huawei.com>
Reviewed-by: Ben Gardiner <ben.l.gardiner@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

When ubifs_init_security() fails, 'ui_mutex' is incorrectly
unlocked and incorrectly restores 'i_size'. Fix this.
Signed-off-by: Taesoo Kim <tsgatesv@gmail.com>
Fixes: d7f0b70d ("UBIFS: Add security.* XATTR support for the UBIFS")
Reviewed-by: Ben Shelton <ben.shelton@ni.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

Merge the upstream -rc5 tag because we needed a more up-to-date base our
further work.

Pull bugfix for md from Neil Brown:
 "One fix for md in 4.0-rc4

  Regression in recent patch causes crash on error path"

* tag 'md/4.0-rc4-fix' of git://neil.brown.name/md:
  md: fix problems with freeing private data after ->run failure.

Pull driver core fixes from Greg KH:
 "Here are two bugfixes for things reported.  One regression in kernfs,
  and another issue fixed in the LZ4 code that was fixed in the
  "upstream" codebase that solves a reported kernel crash

  Both have been in linux-next for a while"

* tag 'driver-core-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  LZ4 : fix the data abort issue
  kernfs: handle poll correctly on 'direct_read' files.

Pull char/misc fixes from Greg KH:
 "Here are three fixes for 4.0-rc5 that revert 3 PCMCIA patches that
  were merged in 4.0-rc1 that cause regressions.  So let's revert them
  for now and they will be reworked and resent sometime in the future.

  All have been tested in linux-next for a while"

* tag 'char-misc-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  Revert "pcmcia: add a new resource manager for non ISA systems"
  Revert "pcmcia: fix incorrect bracketing on a test"
  Revert "pcmcia: add missing include for new pci resource handler"

Pull staging driver fixes from Greg KH:
 "Here are four small staging driver fixes, all for the vt6656 and
  vt6655 drivers, that resolve some reported issues with them.

  All of these patches have been in linux next for a while"

* tag 'staging-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  vt6655: Fix late setting of byRFType.
  vt6655: RFbSetPower fix missing rate RATE_12M
  staging: vt6656: vnt_rf_setpower: fix missing rate RATE_12M
  staging: vt6655: vnt_tx_packet fix dma_idx selection.

Pull tty/serial driver fix from Greg KH:
 "Here's a single 8250 serial driver that fixes a reported deadlock with
  the serial console and the tty driver.

  It's been in linux-next for a while now"

* tag 'tty-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: 8250_dw: Fix deadlock in LCR workaround

Pull USB / PHY driver fixes from Greg KH:
 "Here's a number of USB and PHY driver fixes for 4.0-rc5.

  The largest thing here is a revert of a gadget function driver patch
  that removes 500 lines of code.  Other than that, it's a number of
  reported bugs fixes and new quirk/id entries.

  All have been in linux-next for a while"

* tag 'usb-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (33 commits)
  usb: common: otg-fsm: only signal connect after switching to peripheral
  uas: Add US_FL_NO_ATA_1X for Initio Corporation controllers / devices
  USB: ehci-atmel: rework clk handling
  MAINTAINERS: add entry for USB OTG FSM
  usb: chipidea: otg: add a_alt_hnp_support response for B device
  phy: omap-usb2: Fix missing clk_prepare call when using old dt name
  phy: ti/omap: Fix modalias
  phy: core: Fixup return value of phy_exit when !pm_runtime_enabled
  phy: miphy28lp: Convert to devm_kcalloc and fix wrong sizof
  phy: miphy365x: Convert to devm_kcalloc and fix wrong sizeof
  phy: twl4030-usb: Remove redundant assignment for twl->linkstat
  phy: exynos5-usbdrd: Fix off-by-one valid value checking for args->args[0]
  phy: Find the right match in devm_phy_destroy()
  phy: rockchip-usb: Fixup rockchip_usb_phy_power_on failure path
  phy: ti-pipe3: Simplify ti_pipe3_dpll_wait_lock implementation
  phy: samsung-usb2: Remove NULL terminating entry from phys array
  phy: hix5hd2-sata: Check return value of platform_get_resource
  phy: exynos-dp-video: Kill exynos_dp_video_phy_pwr_isol function
  Revert "usb: gadget: zero: Add support for interrupt EP"
  Revert "xhci: Clear the host side toggle manually when endpoint is 'soft reset'"
  ...

Pull slave dmaengine fixes from Vinod Koul:
 "Four fixes for dw, pl08x, imx-sdma and at_hdmac driver.  Nothing
  unusual here, simple fixes to these drivers"

* 'fixes' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: pl08x: Define capabilities for generic capabilities reporting
  dmaengine: dw: append MODULE_ALIAS for platform driver
  dmaengine: imx-sdma: switch to dynamic context mode after script loaded
  dmaengine: at_hdmac: Fix calculation of the residual bytes

Pull power management and ACPI fixes from Rafael Wysocki:
 "These are fixes for recent regressions (PCI/ACPI resources and at91
  RTC locking), a stable-candidate powercap RAPL driver fix and two ARM
  cpuidle fixes (one stable-candidate too).

  Specifics:

   - Revert a recent PCI commit related to IRQ resources management that
     introduced a regression for drivers attempting to bind to devices
     whose previous drivers did not balance pci_enable_device() and
     pci_disable_device() as expected (Rafael J Wysocki).

   - Fix a deadlock in at91_rtc_interrupt() introduced by a typo in a
     recent commit related to wakeup interrupt handling (Dan Carpenter).

   - Allow the power capping RAPL (Running-Average Power Limit) driver
     to use different energy units for domains within one CPU package
     which is necessary to handle Intel Haswell EP processors correctly
     (Jacob Pan).

   - Improve the cpuidle mvebu driver's handling of Armada XP SoCs by
     updating the target residency and exit latency numbers for those
     chips (Sebastien Rannou).

   - Prevent the cpuidle mvebu driver from calling cpu_pm_enter() twice
     in a row before cpu_pm_exit() is called on the same CPU which
     breaks the core's assumptions regarding the usage of those
     functions (Gregory Clement)"

* tag 'pm+acpi-4.0-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  Revert "x86/PCI: Refine the way to release PCI IRQ resources"
  rtc: at91rm9200: double locking bug in at91_rtc_interrupt()
  powercap / RAPL: handle domains with different energy units
  cpuidle: mvebu: Update cpuidle thresholds for Armada XP SOCs
  cpuidle: mvebu: Fix the CPU PM notifier usage

Pull drm updates from Dave Airlie:
 "A bunch of fixes across drivers:

  radeon:
     disable two ended allocation for now, it breaks some stuff

  amdkfd:
     misc fixes

  nouveau:
     fix irq loop problem, add basic support for GM206 (new hw)

  i915:
     fix some WARNs people were seeing

  exynos:
     fix some iommu interactions causing boot failures"

* git://people.freedesktop.org/~airlied/linux:
  drm/radeon: drop ttm two ended allocation
  drm/exynos: fix the initialization order in FIMD
  drm/exynos: fix typo config name correctly.
  drm/exynos: Check for NULL dereference of crtc
  drm/exynos: IS_ERR() vs NULL bug
  drm/exynos: remove unused files
  drm/i915: Make sure the primary plane is enabled before reading out the fb state
  drm/nouveau/bios: fix i2c table parsing for dcb 4.1
  drm/nouveau/device/gm100: Basic GM206 bring up (as copy of GM204)
  drm/nouveau/device: post write to NV_PMC_BOOT_1 when flipping endian switch
  drm/nouveau/gr/gf100: fix some accidental or'ing of buffer addresses
  drm/nouveau/fifo/nv04: remove the loop from the interrupt handler
  drm/radeon: Changing number of compute pipe lines
  drm/amdkfd: Fix SDMA queue init. in non-HWS mode
  drm/amdkfd: destroy mqd when destroying kernel queue
  drm/i915: Ensure plane->state->fb stays in sync with plane->fb

Merge tag 'devicetree-fixes-for-4.0-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux

Pull more DeviceTree fixes vfom Rob Herring:

 - revert setting stdout-path as preferred console.  This caused
   regressions in PowerMACs and other systems.

 - yet another fix for stdout-path option parsing.

 - fix error path handling in of_irq_parse_one

* tag 'devicetree-fixes-for-4.0-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  Revert "of: Fix premature bootconsole disable with 'stdout-path'"
  of: handle both '/' and ':' in path strings
  of: unittest: Add option string test case with longer path
  of/irq: Fix of_irq_parse_one() returned error codes

Pull SCSI target fixes from Nicholas Bellinger:
 "Here are current target-pending fixes for v4.0-rc5 code that have made
  their way into the queue over the last weeks.

  The fixes this round include:

   - Fix long-standing iser-target logout bug related to early
     conn_logout_comp completion, resulting in iscsi_conn use-after-tree
     OOpsen.  (Sagi + nab)

   - Fix long-standing tcm_fc bug in ft_invl_hw_context() failure
     handing for DDP hw offload.  (DanC)

   - Fix incorrect use of unprotected __transport_register_session() in
     tcm_qla2xxx + other single local se_node_acl fabrics.  (Bart)

   - Fix reference leak in target_submit_cmd() -> target_get_sess_cmd()
     for ack_kref=1 failure path.  (Bart)

   - Fix pSCSI backend ->get_device_type() statistics OOPs with
     un-configured device.  (Olaf + nab)

   - Fix virtual LUN=0 target_configure_device failure OOPs at modprobe
     time.  (Claudio + nab)

   - Fix FUA write false positive failure regression in v4.0-rc1 code.
     (Christophe Vu-Brugier + HCH)"

* git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending:
  target: do not reject FUA CDBs when write cache is enabled but emulate_write_cache is 0
  target: Fix virtual LUN=0 target_configure_device failure OOPs
  target/pscsi: Fix NULL pointer dereference in get_device_type
  tcm_fc: missing curly braces in ft_invl_hw_context()
  target: Fix reference leak in target_get_sess_cmd() error path
  loop/usb/vhost-scsi/xen-scsiback: Fix use of __transport_register_session
  tcm_qla2xxx: Fix incorrect use of __transport_register_session
  iscsi-target: Avoid early conn_logout_comp for iser connections
  Revert "iscsi-target: Avoid IN_LOGOUT failure case for iser-target"
  target: Disallow changing of WRITE cache/FUA attrs after export

Pull devicemapper fixes from Mike Snitzer:
 "A handful of stable fixes for DM:
   - fix thin target to always zero-fill reads to unprovisioned blocks
   - fix to interlock device destruction's suspend from internal
     suspends
   - fix 2 snapshot exception store handover bugs
   - fix dm-io to cope with DISCARD and WRITE_SAME capabilities changing"

* tag 'dm-4.0-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
  dm io: deal with wandering queue limits when handling REQ_DISCARD and REQ_WRITE_SAME
  dm snapshot: suspend merging snapshot when doing exception handover
  dm snapshot: suspend origin when doing exception handover
  dm: hold suspend_lock while suspending device during device deletion
  dm thin: fix to consistently zero-fill reads to unprovisioned blocks

Pull btrfs fixes from Chris Mason:
 "Most of these are fixing extent reservation accounting, or corners
  with tree writeback during commit.

  Josef's set does add a test, which isn't strictly a fix, but it'll
  keep us from making this same mistake again"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  Btrfs: fix outstanding_extents accounting in DIO
  Btrfs: add sanity test for outstanding_extents accounting
  Btrfs: just free dummy extent buffers
  Btrfs: account merges/splits properly
  Btrfs: prepare block group cache before writing
  Btrfs: fix ASSERT(list_empty(&cur_trans->dirty_bgs_list)
  Btrfs: account for the correct number of extents for delalloc reservations
  Btrfs: fix merge delalloc logic
  Btrfs: fix comp_oper to get right order
  Btrfs: catch transaction abortion after waiting for it
  btrfs: fix sizeof format specifier in btrfs_check_super_valid()

Pull nfsd bufix from Bruce Fields:
 "This is a fix for a crash easily triggered by 4.1 activity to a server
  built with CONFIG_NFSD_PNFS.

  There are some more bugfixes queued up that I intend to pass along
  next week, but this is the most critical"

* 'for-4.0' of git://linux-nfs.org/~bfields/linux:
  Subject: nfsd: don't recursively call nfsd4_cb_layout_fail

Pull UBI fix from Artem Bityutskiy:
 "This fixes a bug introduced during the v4.0 merge window where we
  forgot to put braces where they should be"

* tag 'upstream-4.0-rc5' of git://git.infradead.org/linux-ubifs:
  UBI: fix missing brace control flow

Pull arm64 fixes from Catalin Marinas:

 - mm switching fix where the kernel pgd ends up in the user TTBR0 after
   returning from an EFI run-time services call

 - fix __GFP_ZERO handling for atomic pool and CMA DMA allocations (the
   generic code does get the gfp flags, so it's left with the arch code
   to memzero accordingly)

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Honor __GFP_ZERO in dma allocations
  arm64: efi: don't restore TTBR0 if active_mm points at init_mm

Pull ARM fixes from Russell King:
 "Another few ARM fixes.  Fabrice fixed the L2 cache DT parsing to allow
  prefetch configuration to be specified even when the cache size
  parsing fails.

  Laura noticed that the setting of page attributes wasn't working for
  modules due to is_module_addr() always returning false.

  Marc Gonzalez (aka Mason) noticed a potential latent bug with the way
  we read one of the CPUID registers (where we could attempt to read a
  non-present CPUID register which may fault.)

  I've fixed an issue where 32-bit DMA masks were failing with memory
  which extended to the top of physical address space, and I've also
  added debugging output of the page tables when we hit a data access
  exception which we don't specifically handle - prompted by the lack of
  information in a bug report"

* 'fixes' of git://ftp.arm.linux.org.uk/~rmk/linux-arm:
  ARM: 8313/1: Use read_cpuid_ext() macro instead of inline asm
  ARM: 8311/1: Don't use is_module_addr in setting page attributes
  ARM: 8310/1: l2c: Fix prefetch settings dt parsing
  ARM: dump pgd, pmd and pte states on unhandled data abort faults
  ARM: dma-api: fix off-by-one error in __dma_supported()

* pm-cpuidle:
  cpuidle: mvebu: Update cpuidle thresholds for Armada XP SOCs
  cpuidle: mvebu: Fix the CPU PM notifier usage

* powercap:
  powercap / RAPL: handle domains with different energy units

* irq-pm:
  rtc: at91rm9200: double locking bug in at91_rtc_interrupt()

* acpi-resources:
  Revert "x86/PCI: Refine the way to release PCI IRQ resources"

If ->run() fails, it can either free the data structures it
allocated, or leave that task to ->free() which will be called
on failures.

However:
  md.c calls ->free() even if ->private_data is NULL, which
     causes problems in some personalities.
  raid0.c frees the data, but doesn't clear ->private_data,
     which will become a problem when we fix md.c

So better fix both these issues at once.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Fixes: 5aa61f42
URL: https://bugzilla.kernel.org/show_bug.cgi?id=94381Signed-off-by: NeilBrown <neilb@suse.de>

Current implementation doesn't zero out the pages allocated.
Honor the __GFP_ZERO flag and zero out if set.

Cc: <stable@vger.kernel.org> # v3.14+
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

init_mm isn't a normal mm: it has swapper_pg_dir as its pgd (which
contains kernel mappings) and is used as the active_mm for the idle
thread.

When restoring the pgd after an EFI call, we write current->active_mm
into TTBR0. If the current task is actually the idle thread (e.g. when
initialising the EFI RTC before entering userspace), then the TLB can
erroneously populate itself with junk global entries as a result of
speculative table walks.

When we do eventually return to userspace, the task can end up hitting
these junk mappings leading to lockups, corruption or crashes.

This patch fixes the problem in the same way as the CPU suspend code by
ensuring that we never switch to the init_mm in efi_set_pgd and instead
point TTBR0 at the zero page. A check is also added to cpu_switch_mm to
BUG if we get passed swapper_pg_dir.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Fixes: f3cdfd23 ("arm64/efi: move SetVirtualAddressMap() to UEFI stub")
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>