Optimize ChaCha20 NEON performance by:

- Implementing the 8-bit rotations using the 'vtbl.8' instruction.
- Streamlining the part that adds the original state and XORs the data.
- Making some other small tweaks.

On ARM Cortex-A7, these optimizations improve ChaCha20 performance from
about 12.08 cycles per byte to about 11.37 -- a 5.9% improvement.

There is a tradeoff involved with the 'vtbl.8' rotation method since
there is at least one CPU (Cortex-A53) where it's not fastest.  But it
seems to be a better default; see the added comment.  Overall, this
patch reduces Cortex-A53 performance by less than 0.5%.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Add a way to print the currently active CRC algorithm in:

	/sys/module/crc_t10dif/parameters/transform
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

T10 CRC library is linked into the kernel thanks to block and SCSI. The
crypto accelerators are typically loaded later as modules and are
therefore not available when the T10 CRC library is initialized.

Use the crypto notifier facility to trigger a switch to a better algorithm
if one becomes available after the initial hash has been registered. Use
RCU to protect the original transform while the new one is being set up.

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Introduce a facility that can be used to receive a notification
callback when a new algorithm becomes available. This can be used by
existing crypto registrations to trigger a switch from a software-only
algorithm to a hardware-accelerated version.

A new CRYPTO_MSG_ALG_LOADED state is introduced to the existing crypto
notification chain, and the register/unregister functions are exported
so they can be called by subsystems outside of crypto.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The arm64 implementation of the CRC-T10DIF algorithm uses the 64x64 bit
polynomial multiplication instructions, which are optional in the
architecture, and if these instructions are not available, we fall back
to the C routine which is slow and inefficient.

So let's reuse the 64x64 bit PMULL alternative from the GHASH driver that
uses a sequence of ~40 instructions involving 8x8 bit PMULL and some
shifting and masking. This is a lot slower than the original, but it is
still twice as fast as the current [unoptimized] C code on Cortex-A53,
and it is time invariant and much easier on the D-cache.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Reorganize the CRC-T10DIF asm routine so we can easily instantiate an
alternative version based on 8x8 polynomial multiplication in a
subsequent patch.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Now that the scalar fallbacks have been moved out of this driver into
the core crc32()/crc32c() routines, we are left with a CRC32 crypto API
driver for arm64 that is based only on 64x64 polynomial multiplication,
which is an optional instruction in the ARMv8 architecture, and is less
and less likely to be available on cores that do not also implement the
CRC32 instructions, given that those are mandatory in the architecture
as of ARMv8.1.

Since the scalar instructions do not require the special handling that
SIMD instructions do, and since they turn out to be considerably faster
on some cores (Cortex-A53) as well, there is really no point in keeping
this code around so let's just remove it.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Replace the literal load of the addend vector with a sequence that
performs each add individually. This sequence is only 2 instructions
longer than the original, and 2% faster on Cortex-A53.

This is an improvement by itself, but also works around a Clang issue,
whose integrated assembler does not implement the GNU ARM asm syntax
completely, and does not support the =literal notation for FP registers
(more info at https://bugs.llvm.org/show_bug.cgi?id=38642)

Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Speed up the GHASH algorithm based on 64-bit polynomial multiplication
by adding support for 4-way aggregation. This improves throughput by
~85% on Cortex-A53, from 1.7 cycles per byte to 0.9 cycles per byte.

When combined with AES into GCM, throughput improves by ~25%, from
3.8 cycles per byte to 3.0 cycles per byte.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

As it turns out, the AVX2 multibuffer SHA routines are currently
broken [0], in a way that would have likely been noticed if this
code were in wide use. Since the code is too complicated to be
maintained by anyone except the original authors, and since the
performance benefits for real-world use cases are debatable to
begin with, it is better to drop it entirely for the moment.

[0] https://marc.info/?l=linux-crypto-vger&m=153476243825350&w=2Suggested-by: Eric Biggers <ebiggers@google.com>
Cc: Megha Dey <megha.dey@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Adopt the SPDX license identifiers to ease license compliance
management.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Currently, the CCP driver assumes that the SEV command issued to the PSP
will always return (i.e. it will never hang).  But recently, firmware bugs
have shown that a command can hang.  Since of the SEV commands are used
in probe routines, this can cause boot hangs and/or loss of virtualization
capabilities.

To protect against firmware bugs, add a timeout in the SEV command
execution flow.  If a command does not complete within the specified
timeout then return -ETIMEOUT and stop the driver from executing any
further commands since the state of the SEV firmware is unknown.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gary Hook <Gary.Hook@amd.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the newly defined max alignment to perform unaligned hashing to avoid
VLAs, and drops the helper function while adding sanity checks on the
resulting buffer sizes. Additionally, the __aligned_largest macro is
removed since this helper was the only user.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the new upper bound for the stack buffer. Also adds a sanity check.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this
exposes a new general upper bound on crypto blocksize and alignmask
(higher than for the existing cipher limits) for VLA removal,
and introduces new checks.

At present, the highest cra_alignmask in the kernel is 63. The highest
cra_blocksize is 144 (SHA3_224_BLOCK_SIZE, 18 8-byte words). For the
new blocksize limit, I went with 160 (20 8-byte words).

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this
removes the VLAs in SHASH_DESC_ON_STACK (via crypto_shash_descsize())
by using the maximum allowable size (which is now more clearly captured
in a macro), along with a few other cases. Similar limits are turned into
macros as well.

A review of existing sizes shows that SHA512_DIGEST_SIZE (64) is the
largest digest size and that sizeof(struct sha3_state) (360) is the
largest descriptor size. The corresponding maximums are reduced.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this drops
AHASH_REQUEST_ON_STACK by preallocating the ahash request area combined
with the skcipher area (which are not used at the same time).

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this
uses the upper bounds on blocksize. Since this is always a cipher
blocksize, use the existing cipher max blocksize.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

In the quest to remove all stack VLA usage from the kernel[1], this uses
the maximum blocksize and adds a sanity check. For xcbc, the blocksize
must always be 16, so use that, since it's already being enforced during
instantiation.

[1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.comSigned-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

These are unused, undesired, and have never actually been used by
anybody. The original authors of this code have changed their mind about
its inclusion. While originally proposed for disk encryption on low-end
devices, the idea was discarded [1] in favor of something else before
that could really get going. Therefore, this patch removes Speck.

[1] https://marc.info/?l=linux-crypto-vger&m=153359499015659Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Eric Biggers <ebiggers@google.com>
Cc: stable@vger.kernel.org
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Convert driver from deprecated ablkcipher API to skcipher.

Link: https://www.mail-archive.com/search?l=mid&q=20170728085622.GC19664@gondor.apana.org.auSigned-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Convert driver from deprecated ablkcipher API to skcipher.

Link: https://www.mail-archive.com/search?l=mid&q=20170728085622.GC19664@gondor.apana.org.auSigned-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

IV generation is done only at AEAD level.
Support in ablkcipher is not needed, thus remove the dead code.

Link: https://www.mail-archive.com/search?l=mid&q=20160901101257.GA3362@gondor.apana.org.aSigned-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

IV generation is done only at AEAD level.
Support in ablkcipher is not needed, thus remove the dead code.

Link: https://www.mail-archive.com/search?l=mid&q=20160901101257.GA3362@gondor.apana.org.auSigned-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Pull devicetree updates from Rob Herring:
 "A couple of new helper functions in preparation for some tree wide
  clean-ups.

  I'm sending these new helpers now for rc2 in order to simplify the
  dependencies on subsequent cleanups across the tree in 4.20"

* tag 'devicetree-fixes-for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
  of: Add device_type access helper functions
  of: add node name compare helper functions
  of: add helper to lookup compatible child node

Pull ARM SoC fixes from Olof Johansson:
 "First batch of fixes post-merge window:

   - A handful of devicetree changes for i.MX2{3,8} to change over to
     new panel bindings. The platforms were moved from legacy
     framebuffers to DRM and some development board panels hadn't yet
     been converted.

   - OMAP fixes related to ti-sysc driver conversion fallout, fixing
     some register offsets, no_console_suspend fixes, etc.

   - Droid4 changes to fix flaky eMMC probing and vibrator DTS mismerge.

   - Fixed 0755->0644 permissions on a newly added file.

   - Defconfig changes to make ARM Versatile more useful with QEMU
     (helps testing).

   - Enable defconfig options for new TI SoC platform that was merged
     this window (AM6)"

* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  arm64: defconfig: Enable TI's AM6 SoC platform
  ARM: defconfig: Update the ARM Versatile defconfig
  ARM: dts: omap4-droid4: Fix emmc errors seen on some devices
  ARM: dts: Fix file permission for am335x-osd3358-sm-red.dts
  ARM: imx_v6_v7_defconfig: Select CONFIG_DRM_PANEL_SEIKO_43WVF1G
  ARM: mxs_defconfig: Select CONFIG_DRM_PANEL_SEIKO_43WVF1G
  ARM: dts: imx23-evk: Convert to the new display bindings
  ARM: dts: imx23-evk: Move regulators outside simple-bus
  ARM: dts: imx28-evk: Convert to the new display bindings
  ARM: dts: imx28-evk: Move regulators outside simple-bus
  Revert "ARM: dts: imx7d: Invert legacy PCI irq mapping"
  arm: dts: am4372: setup rtc as system-power-controller
  ARM: dts: omap4-droid4: fix vibrations on Droid 4
  bus: ti-sysc: Fix no_console_suspend handling
  bus: ti-sysc: Fix module register ioremap for larger offsets
  ARM: OMAP2+: Fix module address for modules using mpu_rt_idx
  ARM: OMAP2+: Fix null hwmod for ti-sysc debug

Pull x86 fixes from Thomas Gleixner:
 "Speculation:

   - Make the microcode check more robust

   - Make the L1TF memory limit depend on the internal cache physical
     address space and not on the CPUID advertised physical address
     space, which might be significantly smaller. This avoids disabling
     L1TF on machines which utilize the full physical address space.

   - Fix the GDT mapping for EFI calls on 32bit PTI

   - Fix the MCE nospec implementation to prevent #GP

  Fixes and robustness:

   - Use the proper operand order for LSL in the VDSO

   - Prevent NMI uaccess race against CR3 switching

   - Add a lockdep check to verify that text_mutex is held in
     text_poke() functions

   - Repair the fallout of giving native_restore_fl() a prototype

   - Prevent kernel memory dumps based on usermode RIP

   - Wipe KASAN shadow stack before rewinding the stack to prevent false
     positives

   - Move the AMS GOTO enforcement to the actual build stage to allow
     user API header extraction without a compiler

   - Fix a section mismatch introduced by the on demand VDSO mapping
     change

  Miscellaneous:

   - Trivial typo, GCC quirk removal and CC_SET/OUT() cleanups"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/pti: Fix section mismatch warning/error
  x86/vdso: Fix lsl operand order
  x86/mce: Fix set_mce_nospec() to avoid #GP fault
  x86/efi: Load fixmap GDT in efi_call_phys_epilog()
  x86/nmi: Fix NMI uaccess race against CR3 switching
  x86: Allow generating user-space headers without a compiler
  x86/dumpstack: Don't dump kernel memory based on usermode RIP
  x86/asm: Use CC_SET()/CC_OUT() in __gen_sigismember()
  x86/alternatives: Lockdep-enforce text_mutex in text_poke*()
  x86/entry/64: Wipe KASAN stack shadow before rewind_stack_do_exit()
  x86/irqflags: Mark native_restore_fl extern inline
  x86/build: Remove jump label quirk for GCC older than 4.5.2
  x86/Kconfig: Fix trivial typo
  x86/speculation/l1tf: Increase l1tf memory limit for Nehalem+
  x86/spectre: Add missing family 6 check to microcode check

Pull CPU hotplug fix from Thomas Gleixner:
 "Remove the stale skip_onerr member from the hotplug states"

* 'smp-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Remove skip_onerr field from cpuhp_step structure

Pull core fixes from Thomas Gleixner:
 "A small set of updates for core code:

   - Prevent tracing in functions which are called from trace patching
     via stop_machine() to prevent executing half patched function trace
     entries.

   - Remove old GCC workarounds

   - Remove pointless includes of notifier.h"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Remove workaround for unreachable warnings from old GCC
  notifier: Remove notifier header file wherever not used
  watchdog: Mark watchdog touch functions as notrace

Fix the section mismatch warning in arch/x86/mm/pti.c:

WARNING: vmlinux.o(.text+0x6972a): Section mismatch in reference from the function pti_clone_pgtable() to the function .init.text:pti_user_pagetable_walk_pte()
The function pti_clone_pgtable() references
the function __init pti_user_pagetable_walk_pte().
This is often because pti_clone_pgtable lacks a __init
annotation or the annotation of pti_user_pagetable_walk_pte is wrong.
FATAL: modpost: Section mismatches detected.

Fixes: 85900ea5 ("x86/pti: Map the vsyscall page if needed")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/43a6d6a3-d69d-5eda-da09-0b1c88215a2a@infradead.org

Merge tag 'omap-for-v4.19/fixes-v2-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap into fixes

Fixes for omap variants against v4.19-rc1

These are mostly fixes related to using ti-sysc interconnect target module
driver for accessing right register offsets for sgx and cpsw and for
no_console_suspend regression.

There is also a droid4 emmc fix where emmc may not get detected for some
models, and vibrator dts mismerge fix.

And we have a file permission fix for am335x-osd3358-sm-red.dts that
just got added. And we must tag RTC as system-power-controller for
am437x for PMIC to shut down during poweroff.

* tag 'omap-for-v4.19/fixes-v2-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap:
  ARM: dts: omap4-droid4: Fix emmc errors seen on some devices
  ARM: dts: Fix file permission for am335x-osd3358-sm-red.dts
  arm: dts: am4372: setup rtc as system-power-controller
  ARM: dts: omap4-droid4: fix vibrations on Droid 4
  bus: ti-sysc: Fix no_console_suspend handling
  bus: ti-sysc: Fix module register ioremap for larger offsets
  ARM: OMAP2+: Fix module address for modules using mpu_rt_idx
  ARM: OMAP2+: Fix null hwmod for ti-sysc debug
Signed-off-by: Olof Johansson <olof@lixom.net>

In the __getcpu function, lsl is using the wrong target and destination
registers. Luckily, the compiler tends to choose %eax for both variables,
so it has been working so far.

Fixes: a582c540 ("x86/vdso: Use RDPID in preference to LSL when available")
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180901201452.27828-1-sneves@dei.uc.pt

Pull watchdog fixlet from Wim Van Sebroeck:
 "Document support for r8a774a1"

* tag 'linux-watchdog-4.19-rc2' of git://www.linux-watchdog.org/linux-watchdog:
  dt-bindings: watchdog: renesas-wdt: Document r8a774a1 support

Pull clk fixes from Stephen Boyd:
 "Two small fixes, one for the x86 Stoney SoC to get a more accurate clk
  frequency and the other to fix a bad allocation in the Nuvoton NPCM7XX
  driver"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: x86: Set default parent to 48Mhz
  clk: npcm7xx: fix memory allocation

The trick with flipping bit 63 to avoid loading the address of the 1:1
mapping of the poisoned page while the 1:1 map is updated used to work when
unmapping the page. But it falls down horribly when attempting to directly
set the page as uncacheable.

The problem is that when the cache mode is changed to uncachable, the pages
needs to be flushed from the cache first. But the decoy address is
non-canonical due to bit 63 flipped, and the CLFLUSH instruction throws a
#GP fault.

Add code to change_page_attr_set_clr() to fix the address before calling
flush.

Fixes: 284ce401 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: linux-edac <linux-edac@vger.kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Link: https://lkml.kernel.org/r/20180831165506.GA9605@agluck-desk

Pull arm64 fixes from Will Deacon:
 "A few arm64 fixes came in this week, specifically fixing some nasty
  truncation of return values from firmware calls and resolving a
  VM_BUG_ON due to accessing uninitialised struct pages corresponding to
  NOMAP pages.

  Summary:

   - Fix typos in SVE documentation

   - Fix type-checking and implicit truncation for SMCCC calls

   - Force CONFIG_HOLES_IN_ZONE=y so that SLAB doesn't fall over NOMAP
     regions"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: mm: always enable CONFIG_HOLES_IN_ZONE
  arm/arm64: smccc-1.1: Handle function result as parameters
  arm/arm64: smccc-1.1: Make return values unsigned long
  Documentation/arm64/sve: Couple of improvements and typos

When PTI is enabled on x86-32 the kernel uses the GDT mapped in the fixmap
for the simple reason that this address is also mapped for user-space.

The efi_call_phys_prolog()/efi_call_phys_epilog() wrappers change the GDT
to call EFI runtime services and switch back to the kernel GDT when they
return. But the switch-back uses the writable GDT, not the fixmap GDT.

When that happened and and the CPU returns to user-space it switches to the
user %cr3 and tries to restore user segment registers. This fails because
the writable GDT is not mapped in the user page-table, and without a GDT
the fault handlers also can't be launched. The result is a triple fault and
reboot of the machine.

Fix that by restoring the GDT back to the fixmap GDT which is also mapped
in the user page-table.

Fixes: 7757d607 x86/pti: ('Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32')
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: hpa@zytor.com
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/1535702738-10971-1-git-send-email-joro@8bytes.org

Pull xen fixes from Juergen Gross:

 - minor cleanup avoiding a warning when building with new gcc

 - a patch to add a new sysfs node for Xen frontend/backend drivers to
   make it easier to obtain the state of a pv device

 - two fixes for 32-bit pv-guests to avoid intermediate L1TF vulnerable
   PTEs

* tag 'for-linus-4.19b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  x86/xen: remove redundant variable save_pud
  xen: export device state to sysfs
  x86/pae: use 64 bit atomic xchg function in native_ptep_get_and_clear
  x86/xen: don't write ptes directly in 32-bit PV guests

Pull m68k fix from Geert Uytterhoeven:
 "Just a single fix for a bug introduced during the merge window: fix
  wrong date and time on PMU-based Macs"

* tag 'm68k-for-v4.19-tag2' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k:
  m68k/mac: Use correct PMU response format