On physical machine we can save power by disabling clock of hot removed
cpu. However as different platforms require different methods to
configure clocks, the code is platform-specific, and probably belongs to
firmware/pmu or cpu regulator, rather than generic arch/loongarch code.

Also, there is no such register on QEMU virt machine since the
clock/frequency regulation is not emulated.

This patch removes the hard-coded clock register accesses in generic
LoongArch cpu hotplug flow.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

The content of LoongArch's compiler.h is trivial, with some unused
anywhere, so inline the definitions and remove the header.
Signed-off-by: Jun Yi <yijun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

These syntactic sugars have been supported by upstream binutils from the
beginning, so no need to patch them locally.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Reflow the *.S files for better stylistic consistency, namely hard tabs
after mnemonic position, and vertical alignment of the first operand
with hard tabs. Tab width is obviously 8. Some pre-existing intra-block
vertical alignments are preserved.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Support for the syntactic sugar is present in upstream binutils port
from the beginning. Use it for shorter lines and better consistency.
Generated code should be identical.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Support for the syntactic sugar is present in upstream binutils port
from the beginning. Use it for shorter lines and better consistency.
Generated code should be identical.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

While B{EQ,NE}Z and B{EQ,NE} are different instructions, and the vastly
expanded range for branch destination does not really matter in the few
cases touched, use the B{EQ,NE}Z where possible for shorter lines and
better consistency (e.g. some places used "BEQ foo, zero", while some
used "BEQ zero, foo").
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Some of the assembly code in the LoongArch port likely originated
from a time when the assembler did not support pseudo-instructions like
"move" or "jr", so the desugared form was used and readability suffers
(to a minor degree) as a result.

As the upstream toolchain supports these pseudo-instructions from the
beginning, migrate the existing few usages to them for better
readability.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Some of the assembly code in the LoongArch port likely originated
from a time when the assembler did not support pseudo-instructions like
"move" or "jr", so the desugared form was used and readability suffers
(to a minor degree) as a result.

As the upstream toolchain supports these pseudo-instructions from the
beginning, migrate the existing few usages to them for better
readability.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

Some of the assembly in the LoongArch port seem to come from a
prehistoric time, when the assembler didn't even have support for the
ABI names we all come to know and love, thus used raw register numbers
which hampered readability.

The usages are found with a regex match inside arch/loongarch, then
manually adjusted for those non-definitions.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

This code requires x509_load_certificate_list() to be built-in.

Fixes: 60050ffe ("certs: Move load_certificate_list() to be with the asymmetric keys code")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Link: https://lore.kernel.org/all/202206221515.DqpUuvbQ-lkp@intel.com/
Link: https://lore.kernel.org/all/20220712104554.408dbf42@gandalf.local.home/Signed-off-by: Adam Borowski <kilobyte@angband.pl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull perf fix from Borislav Petkov:

 - Reorganize the perf LBR init code so that a TSX quirk is applied
   early enough in order for the LBR MSR access to not #GP

* tag 'perf_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/x86/intel/lbr: Fix unchecked MSR access error on HSW

Pull scheduler fix from Borislav Petkov:
 "A single fix to correct a wrong BUG_ON() condition for deboosted
  tasks"

* tag 'sched_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Fix BUG_ON condition for deboosted tasks

Pull x86 fixes from Borislav Petkov:
 "A couple more retbleed fallout fixes.

  It looks like their urgency is decreasing so it seems like we've
  managed to catch whatever snafus the limited -rc testing has exposed.
  Maybe we're getting ready... :)

   - Make retbleed mitigations 64-bit only (32-bit will need a bit more
     work if even needed, at all).

   - Prevent return thunks patching of the LKDTM modules as it is not
     needed there

   - Avoid writing the SPEC_CTRL MSR on every kernel entry on eIBRS
     parts

   - Enhance error output of apply_returns() when it fails to patch a
     return thunk

   - A sparse fix to the sev-guest module

   - Protect EFI fw calls by issuing an IBPB on AMD"

* tag 'x86_urgent_for_v5.19_rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Make all RETbleed mitigations 64-bit only
  lkdtm: Disable return thunks in rodata.c
  x86/bugs: Warn when "ibrs" mitigation is selected on Enhanced IBRS parts
  x86/alternative: Report missing return thunk details
  virt: sev-guest: Pass the appropriate argument type to iounmap()
  x86/amd: Use IBPB for firmware calls

Pull clk fix from Stephen Boyd:
 "One more fix to set the correct IO mapping for a clk gate in the
  lan966x driver"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: lan966x: Fix the lan966x clock gate register address

Pull kvm fixes from Paolo Bonzini:

 - Check for invalid flags to KVM_CAP_X86_USER_SPACE_MSR

 - Fix use of sched_setaffinity in selftests

 - Sync kernel headers to tools

 - Fix KVM_STATS_UNIT_MAX

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Protect the unused bits in MSR exiting flags
  tools headers UAPI: Sync linux/kvm.h with the kernel sources
  KVM: selftests: Fix target thread to be migrated in rseq_test
  KVM: stats: Fix value for KVM_STATS_UNIT_MAX for boolean stats

The mitigations for RETBleed are currently ineffective on x86_32 since
entry_32.S does not use the required macros.  However, for an x86_32
target, the kconfig symbols for them are still enabled by default and
/sys/devices/system/cpu/vulnerabilities/retbleed will wrongly report
that mitigations are in place.

Make all of these symbols depend on X86_64, and only enable RETHUNK by
default on X86_64.

Fixes: f43b9876 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/YtwSR3NNsWp1ohfV@decadent.org.uk

Pull spi fixes from Mark Brown:
 "A few more small driver specific fixes"

* tag 'spi-fix-v5.19-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: spi-rspi: Fix PIO fallback on RZ platforms
  spi: spi-cadence: Fix SPI NO Slave Select macro definition
  spi: bcm2835: bcm2835_spi_handle_err(): fix NULL pointer deref for non DMA transfers

Pull RISC-V fixes from Palmer Dabbelt:

 - Two kexec-related build fixes

 - A DTS update to make the GPIO nodes match the upcoming dtschema

 - A fix that passes -mno-relax directly to the assembler when building
   modules, to work around compilers that fail to do so

* tag 'riscv-for-linus-5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: add as-options for modules with assembly compontents
  riscv: dts: align gpio-key node names with dtschema
  RISC-V: kexec: Fix build error without CONFIG_KEXEC
  RISCV: kexec: Fix build error without CONFIG_MODULES

Pull ACPI fix from Rafael Wysocki:
 "Fix yet another piece of ACPI CPPC changes fallout on AMD platforms
  (Mario Limonciello)"

* tag 'acpi-5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: CPPC: Don't require flexible address space if X86_FEATURE_CPPC is supported

Pull io_uring fixes from Jens Axboe:
 "Fix for a bad kfree() introduced in this cycle, and a quick fix for
  disabling buffer recycling for IORING_OP_READV.

  The latter will get reworked for 5.20, but it gets the job done for
  5.19"

* tag 'io_uring-5.19-2022-07-21' of git://git.kernel.dk/linux-block:
  io_uring: do not recycle buffer in READV
  io_uring: fix free of unallocated buffer list

Pull block fix from Jens Axboe:
 "Just a single fix for missing error propagation for an allocation
  failure in raid5"

* tag 'block-5.19-2022-07-21' of git://git.kernel.dk/linux-block:
  md/raid5: missing error code in setup_conf()

Pull i2c fixes from Wolfram Sang:
 "Two driver bugfixes and a typo fix"

* tag 'i2c-for-5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: cadence: Change large transfer count reset logic to be unconditional
  i2c: imx: fix typo in comment
  i2c: mlxcpld: Fix register setting for 400KHz frequency

Pull gpio fixes from Bartosz Golaszewski:

 - fix several regmap usage issues in gpio-pca953x

 - fix out-of-tree build for GPIO selftests

 - fix integer overflow in gpio-xilinx

* tag 'gpio-fixes-for-v5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux:
  gpio: gpio-xilinx: Fix integer overflow
  selftests: gpio: fix include path to kernel headers for out of tree builds
  gpio: pca953x: use the correct register address when regcache sync during init
  gpio: pca953x: use the correct range when do regmap sync
  gpio: pca953x: only use single read/write for No AI mode

Pull pin control fixes from Linus Walleij:
 "Only driver fixes:

   - NULL check for the ralink and sunplus drivers

   - Add Jacky Bai as maintainer for the Freescale pin controllers

   - Fix pin config ops for the Ocelot LAN966x and SparX5

   - Disallow AMD pin control to be a module: the GPIO lines need to be
     active in early boot, so no can do

   - Fix the Armada 37xx to use raw spinlocks in the interrupt handler
     path to avoid wait context"

* tag 'pinctrl-v5.19-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: armada-37xx: use raw spinlocks for regmap to avoid invalid wait context
  pinctrl: armada-37xx: make irq_lock a raw spinlock to avoid invalid wait context
  pinctrl: Don't allow PINCTRL_AMD to be a module
  pinctrl: ocelot: Fix pincfg
  pinctrl: ocelot: Fix pincfg for lan966x
  MAINTAINERS: Update freescale pin controllers maintainer
  pinctrl: sunplus: Add check for kcalloc
  pinctrl: ralink: Check for null return of devm_kcalloc

Pull sound fixes from Takashi Iwai:
 "Only undoes the Rockchip BCLK changes to address a regression"

* tag 'sound-5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound:
  ASoC: rockchip-i2s: Undo BCLK pinctrl changes
  ASoC: rockchip: i2s: Fix NULL pointer dereference when pinctrl is not found

Pull MMC fix from Ulf Hansson:

 - sdhci-omap: Fix a lockdep warning while probing

* tag 'mmc-v5.19-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: sdhci-omap: Fix a lockdep warning for PM runtime init

Pull drm fixes from Dave Airlie:
 "Fixes for this week.

  The main one is the i915 firmware fix for the phoronix reported issue.
  I've written some firmware guidelines as a result, should land in
  -next soon. Otherwise a few amdgpu fixes, a scheduler fix, ttm fix and
  two other minor ones.

  scheduler:
   - scheduling while atomic fix

  ttm:
   - locking fix

  edp:
   - variable typo fix

  i915:
   - add back support for v69 firmware on ADL-P

  amdgpu:
   - Drop redundant buffer cleanup that can lead to a segfault
   - Add a bo_list mutex to avoid possible list corruption in CS
   - dmub notification fix

  imx:
   - fix error path"

* tag 'drm-fixes-2022-07-22' of git://anongit.freedesktop.org/drm/drm:
  drm/amdgpu: Protect the amdgpu_bo_list list with a mutex v2
  drm/imx/dcss: Add missing of_node_put() in fail path
  drm/i915/guc: support v69 in parallel to v70
  drm/i915/guc: Support programming the EU priority in the GuC descriptor
  drm/panel-edp: Fix variable typo when saving hpd absent delay from DT
  drm/amdgpu: Remove one duplicated ef removal
  drm/ttm: fix locking in vmap/vunmap TTM GEM helpers
  drm/scheduler: Don't kill jobs in interrupt context
  drm/amd/display: Fix new dmub notification enabling in DM

Merge tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull RCU fix from Paul McKenney:
 "This contains a pair of commits that fix 282d8998 ("srcu: Prevent
  expedited GPs and blocking readers from consuming CPU"), which was
  itself a fix to an SRCU expedited grace-period problem that could
  prevent kernel live patching (KLP) from completing.

  That SRCU fix for KLP introduced large (as in minutes) boot-time
  delays to embedded Linux kernels running on qemu/KVM. These delays
  were due to the emulation of certain MMIO operations controlling
  memory layout, which were emulated with one expedited grace period per
  access. Common configurations required thousands of boot-time MMIO
  accesses, and thus thousands of boot-time expedited SRCU grace
  periods.

  In these configurations, the occasional sleeps that allowed KLP to
  proceed caused excessive boot delays. These commits preserve enough
  sleeps to permit KLP to proceed, but few enough that the virtual
  embedded kernels still boot reasonably quickly.

  This represents a regression introduced in the v5.19 merge window, and
  the bug is causing significant inconvenience"

* tag 'rcu-urgent.2022.07.21a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
  srcu: Make expedited RCU grace periods block even less frequently
  srcu: Block less aggressively for expedited grace periods

Sudip reports that alpha doesn't build properly, with errors like

  include/asm-generic/tlb.h:401:1: error: redefinition of 'tlb_update_vma_flags'
    401 | tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma)
        | ^~~~~~~~~~~~~~~~~~~~
  include/asm-generic/tlb.h:372:1: note: previous definition of 'tlb_update_vma_flags' with type 'void(struct mmu_gather *, struct vm_area_struct *)'
    372 | tlb_update_vma_flags(struct mmu_gather *tlb, struct vm_area_struct *vma) { }

the cause being that We have this odd situation where some architectures
were never converted to the newer TLB flushing interfaces that have a
range for the flush.  Instead people left them alone, and we have them
select the MMU_GATHER_NO_RANGE config option to make the tlb header
files account for this.

Peter Zijlstra cleaned some of these nasty header file games up in
commits

  1e9fdf21 ("mmu_gather: Remove per arch tlb_{start,end}_vma()")
  18ba064e ("mmu_gather: Let there be one tlb_{start,end}_vma() implementation")

but tlb_update_vma_flags() was left alone, and then commit b67fbebd
("mmu_gather: Force tlb-flush VM_PFNMAP vmas") ended up removing only
_one_ of the two stale duplicate dummy inline functions.

This removes the other stale one.

Somebody braver than me should try to remove MMU_GATHER_NO_RANGE
entirely, but it requires fixing up the oddball architectures that use
it: alpha, m68k, microblaze, nios2 and openrisc.

The fixups should be fairly straightforward ("fix the build errors it
exposes by adding the appropriate range arguments"), but the reason this
wasn't done in the first place is that so few people end up working on
those architectures.  But it could be done one architecture at a time,
hint, hint.
Reported-by: Sudip Mukherjee (Codethink) <sudipm.mukherjee@gmail.com>
Fixes: b67fbebd ("mmu_gather: Force tlb-flush VM_PFNMAP vmas")
Link: https://lore.kernel.org/all/YtpXh0QHWwaEWVAY@debian/
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Current implementation is not able to configure more than 32 pins
due to incorrect data type. So type casting with unsigned long
to avoid it.

Fixes: 02b3f84d ("xilinx: Switch to use bitmap APIs")
Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

A scheduling-while-atomic fix for drm/scheduler, a locking fix for TTM,
a typo fix for panel-edp and a resource removal fix for imx/dcss
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220721085550.hrwbukj34y56rzva@houat

When trying to load modules built for RISC-V which include assembly files
the kernel loader errors with "unexpected relocation type 'R_RISCV_ALIGN'"
due to R_RISCV_ALIGN relocations being generated by the assembler.

The R_RISCV_ALIGN relocations can be removed at the expense of code space
by adding -mno-relax to gcc and as.  In commit 7a8e7da4
("RISC-V: Fixes to module loading") -mno-relax is added to the build
variable KBUILD_CFLAGS_MODULE. See [1] for more info.

The issue is that when kbuild builds a .S file, it invokes gcc with
the -mno-relax flag, but this is not being passed through to the
assembler. Adding -Wa,-mno-relax to KBUILD_AFLAGS_MODULE ensures that
the assembler is invoked correctly. This may have now been fixed in
gcc[2] and this addition should not stop newer gcc and as from working.

[1] https://github.com/riscv/riscv-elf-psabi-doc/issues/183
[2] https://github.com/gcc-mirror/gcc/commit/3b0a7d624e64eeb81e4d5e8c62c46d86ef521857Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Link: https://lore.kernel.org/r/20220529152200.609809-1-ben.dooks@codethink.co.uk
Fixes: ab1ef68e ("RISC-V: Add sections of PLT and GOT for kernel module")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Pull MTD fix from Richard Weinberger:
 "A aingle NAND controller fix:

   - gpmi: Fix busy timeout setting (wrong calculation, yes again)"

* tag 'mtd/fixes-for-5.19-final' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux:
  mtd: rawnand: gpmi: Set WAIT_FOR_READY timeout based on program/erase times

Pull networking fixes from Paolo Abeni:
 "Including fixes from can.

  Still no major regressions, most of the changes are still due to data
  races fixes, plus the usual bunch of drivers fixes.

  Previous releases - regressions:

   - tcp/udp: make early_demux back namespacified.

   - dsa: fix issues with vlan_filtering_is_global

  Previous releases - always broken:

   - ip: fix data-races around ipv4_net_table (round 2, 3 & 4)

   - amt: fix validation and synchronization bugs

   - can: fix detection of mcp251863

   - eth: iavf: fix handling of dummy receive descriptors

   - eth: lan966x: fix issues with MAC table

   - eth: stmmac: dwmac-mediatek: fix clock issue

  Misc:

   - dsa: update documentation"

* tag 'net-5.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (107 commits)
  mlxsw: spectrum_router: Fix IPv4 nexthop gateway indication
  net/sched: cls_api: Fix flow action initialization
  tcp: Fix data-races around sysctl_tcp_max_reordering.
  tcp: Fix a data-race around sysctl_tcp_abort_on_overflow.
  tcp: Fix a data-race around sysctl_tcp_rfc1337.
  tcp: Fix a data-race around sysctl_tcp_stdurg.
  tcp: Fix a data-race around sysctl_tcp_retrans_collapse.
  tcp: Fix data-races around sysctl_tcp_slow_start_after_idle.
  tcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts.
  tcp: Fix data-races around sysctl_tcp_recovery.
  tcp: Fix a data-race around sysctl_tcp_early_retrans.
  tcp: Fix data-races around sysctl knobs related to SYN option.
  udp: Fix a data-race around sysctl_udp_l3mdev_accept.
  ip: Fix data-races around sysctl_ip_prot_sock.
  ipv4: Fix data-races around sysctl_fib_multipath_hash_fields.
  ipv4: Fix data-races around sysctl_fib_multipath_hash_policy.
  ipv4: Fix a data-race around sysctl_fib_multipath_use_neigh.
  can: rcar_canfd: Add missing of_node_put() in rcar_canfd_probe()
  can: mcp251xfd: fix detection of mcp251863
  Documentation: fix udp_wmem_min in ip-sysctl.rst
  ...

Jann reported a race between munmap() and unmap_mapping_range(), where
unmap_mapping_range() will no-op once unmap_vmas() has unlinked the
VMA; however munmap() will not yet have invalidated the TLBs.

Therefore unmap_mapping_range() will complete while there are still
(stale) TLB entries for the specified range.

Mitigate this by force flushing TLBs for VM_PFNMAP ranges.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Now that architectures are no longer allowed to override
tlb_{start,end}_vma() re-arrange code so that there is only one
implementation for each of these functions.

This much simplifies trying to figure out what they actually do.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The previous patch removed the tlb_flush_end() implementation which
used tlb_flush_range(). This means:

 - csky did double invalidates, a range invalidate per vma and a full
   invalidate at the end

 - csky actually has range invalidates and as such the generic
   tlb_flush implementation is more efficient for it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Tested-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Scattered across the archs are 3 basic forms of tlb_{start,end}_vma().
Provide two new MMU_GATHER_knobs to enumerate them and remove the per
arch tlb_{start,end}_vma() implementations.

 - MMU_GATHER_NO_FLUSH_CACHE indicates the arch has flush_cache_range()
   but does *NOT* want to call it for each VMA.

 - MMU_GATHER_MERGE_VMAS indicates the arch wants to merge the
   invalidate across multiple VMAs if possible.

With these it is possible to capture the three forms:

  1) empty stubs;
     select MMU_GATHER_NO_FLUSH_CACHE and MMU_GATHER_MERGE_VMAS

  2) start: flush_cache_range(), end: empty;
     select MMU_GATHER_MERGE_VMAS

  3) start: flush_cache_range(), end: flush_tlb_range();
     default

Obviously, if the architecture does not have flush_cache_range() then
it also doesn't need to select MMU_GATHER_NO_FLUSH_CACHE.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>