Initialise prefaulted PTEs as 'old' for arm64 when hardware access-flag
updates are supported, which drastically improves vmscan performance.

* for-next/faultaround:
  mm: filemap: Fix microblaze build failure with 'mmu_defconfig'
  mm/nommu: Fix return type of filemap_map_pages()
  mm: Mark anonymous struct field of 'struct vm_fault' as 'const'
  mm: Use static initialisers for immutable fields of 'struct vm_fault'
  mm: Avoid modifying vmf.address in __collapse_huge_page_swapin()
  mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT
  mm: Move immutable fields of 'struct vm_fault' into anonymous struct
  arm64: mm: Implement arch_wants_old_prefaulted_pte()
  mm: Allow architectures to request 'old' entries when prefaulting
  mm: Cleanup faultaround and finish_fault() codepaths

Rework of the workaround for Cortex-A76 erratum 1463225 to fit in better
with the ongoing exception entry cleanups and changes to the detection
code for Cortex-A55 erratum 1024718 since it applies to all revisions of
the silicon.

* for-next/errata:
  arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround
  arm64: Extend workaround for erratum 1024718 to all versions of Cortex-A55

Introduce a new macro to allow yielding the vector unit if preemption
is required. The initial users of this are being merged via the crypto
tree for 5.12.

* for-next/crypto:
  arm64: assembler: add cond_yield macro

Support for overriding CPU ID register fields on the command-line, which
allows us to disable certain features which the kernel would otherwise
use unconditionally when detected.

* for-next/cpufeature: (22 commits)
  arm64: cpufeatures: Allow disabling of Pointer Auth from the command-line
  arm64: Defer enabling pointer authentication on boot core
  arm64: cpufeatures: Allow disabling of BTI from the command-line
  arm64: Move "nokaslr" over to the early cpufeature infrastructure
  KVM: arm64: Document HVC_VHE_RESTART stub hypercall
  arm64: Make kvm-arm.mode={nvhe, protected} an alias of id_aa64mmfr1.vh=0
  arm64: Add an aliasing facility for the idreg override
  arm64: Honor VHE being disabled from the command-line
  arm64: Allow ID_AA64MMFR1_EL1.VH to be overridden from the command line
  arm64: cpufeature: Add an early command-line cpufeature override facility
  arm64: Extract early FDT mapping from kaslr_early_init()
  arm64: cpufeature: Use IDreg override in __read_sysreg_by_encoding()
  arm64: cpufeature: Add global feature override facility
  arm64: Move SCTLR_EL1 initialisation to EL-agnostic code
  arm64: Simplify init_el2_state to be non-VHE only
  arm64: Move VHE-specific SPE setup to mutate_to_vhe()
  arm64: Drop early setting of MDSCR_EL2.TPMS
  arm64: Initialise as nVHE before switching to VHE
  arm64: Provide an 'upgrade to VHE' stub hypercall
  arm64: Turn the MMU-on sequence into a macro
  ...

Cosmetic changes to tidy up stale comments and fix inconsistent
whitespace. No functional changes here!

* for-next/cosmetic:
  mm/arm64: Correct obsolete comment in do_page_fault()
  arm64: improve whitespace

Commit f9ce0be7 ("mm: Cleanup faultaround and finish_fault()
codepaths") added a call to 'update_mmu_cache()' in mm/filemap.c, which
breaks the build for microblaze:

  | mm/filemap.c: In function 'filemap_map_pages':
  | mm/filemap.c:3153:3: error: implicit declaration of function 'update_mmu_cache'; did you mean 'update_mmu_tlb'?

Include asm/tlbflush.h in mm/filemap.c to make sure that the function
(or indeed, macro) is available.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210209202449.GA104837@roeck-us.netSigned-off-by: Will Deacon <will@kernel.org>

In order to be able to disable Pointer Authentication  at runtime,
whether it is for testing purposes, or to work around HW issues,
let's add support for overriding the ID_AA64ISAR1_EL1.{GPI,GPA,API,APA}
fields.

This is further mapped on the arm64.nopauth command-line alias.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Tested-by: Srinivas Ramana <sramana@codeaurora.org>
Link: https://lore.kernel.org/r/20210208095732.3267263-23-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Defer enabling pointer authentication on boot core until
after its required to be enabled by cpufeature framework.
This will help in controlling the feature dynamically
with a boot parameter.
Signed-off-by: Ajay Patil <pajay@qti.qualcomm.com>
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/1610152163-16554-2-git-send-email-sramana@codeaurora.orgReviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-22-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In order to be able to disable BTI at runtime, whether it is
for testing purposes, or to work around HW issues, let's add
support for overriding the ID_AA64PFR1_EL1.BTI field.

This is further mapped on the arm64.nobti command-line alias.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Tested-by: Srinivas Ramana <sramana@codeaurora.org>
Link: https://lore.kernel.org/r/20210208095732.3267263-21-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Given that the early cpufeature infrastructure has borrowed quite
a lot of code from the kaslr implementation, let's reimplement
the matching of the "nokaslr" option with it.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-20-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

For completeness, let's document the HVC_VHE_RESTART stub.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-19-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Admitedly, passing id_aa64mmfr1.vh=0 on the command-line isn't
that easy to understand, and it is likely that users would much
prefer write "kvm-arm.mode=nvhe", or "...=protected".

So here you go. This has the added advantage that we can now
always honor the "kvm-arm.mode=protected" option, even when
booting on a VHE system.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-18-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In order to map the override of idregs to options that a user
can easily understand, let's introduce yet another option
array, which maps an option to the corresponding idreg options.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-17-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Finally we can check whether VHE is disabled on the command line,
and not enable it if that's the user's wish.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-16-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As we want to be able to disable VHE at runtime, let's match
"id_aa64mmfr1.vh=" from the command line as an override.
This doesn't have much effect yet as our boot code doesn't look
at the cpufeature, but only at the HW registers.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-15-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

In order to be able to override CPU features at boot time,
let's add a command line parser that matches options of the
form "cpureg.feature=value", and store the corresponding
value into the override val/mask pair.

No features are currently defined, so no expected change in
functionality.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-14-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As we want to parse more options very early in the kernel lifetime,
let's always map the FDT early. This is achieved by moving that
code out of kaslr_early_init().

No functional change expected.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-13-maz@kernel.org
[will: Ensue KASAN is enabled before running C code]
Signed-off-by: Will Deacon <will@kernel.org>

__read_sysreg_by_encoding() is used by a bunch of cpufeature helpers,
which should take the feature override into account. Let's do that.

For a good measure (and because we are likely to need to further
down the line), make this helper available to the rest of the
non-modular kernel.

Code that needs to know the *real* features of a CPU can still
use read_sysreg_s(), and find the bare, ugly truth.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-12-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Add a facility to globally override a feature, no matter what
the HW says. Yes, this sounds dangerous, but we do respect the
"safe" value for a given feature. This doesn't mean the user
doesn't need to know what they are doing.

Nothing uses this yet, so we are pretty safe. For now.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-11-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

We can now move the initial SCTLR_EL1 setup to be used for both
EL1 and EL2 setup.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-10-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As init_el2_state is now nVHE only, let's simplify it and drop
the VHE setup.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-9-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

There isn't much that a VHE kernel needs on top of whatever has
been done for nVHE, so let's move the little we need to the
VHE stub (the SPE setup), and drop the init_el2_state macro.

No expected functional change.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-8-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

When running VHE, we set MDSCR_EL2.TPMS very early on to force
the trapping of EL1 SPE accesses to EL2.

However:
- we are running with HCR_EL2.{E2H,TGE}={1,1}, meaning that there
  is no EL1 to trap from

- before entering a guest, we call kvm_arm_setup_debug(), which
  sets MDCR_EL2_TPMS in the per-vcpu shadow mdscr_el2, which gets
  applied on entry by __activate_traps_common().

The early setting of MDSCR_EL2.TPMS is therefore useless and can
be dropped.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210208095732.3267263-7-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

As we are aiming to be able to control whether we enable VHE or
not, let's always drop down to EL1 first, and only then upgrade
to VHE if at all possible.

This means that if the kernel is booted at EL2, we always start
with a nVHE init, drop to EL1 to initialise the the kernel, and
only then upgrade the kernel EL to EL2 if possible (the process
is obviously shortened for secondary CPUs).

The resume path is handled similarly to a secondary CPU boot.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-6-maz@kernel.org
[will: Avoid calling switch_to_vhe twice on kaslr path]
Signed-off-by: Will Deacon <will@kernel.org>

The workaround for Cortex-A76 erratum 1463225 is split across the
syscall and debug handlers in separate files. This structure currently
forces us to do some redundant work for debug exceptions from EL0, is a
little difficult to follow, and gets in the way of some future rework of
the exception entry code as it requires exceptions to be unmasked late
in the syscall handling path.

To simplify things, and as a preparatory step for future rework of
exception entry, this patch moves all the workaround logic into
entry-common.c. As the debug handler only needs to run for EL1 debug
exceptions, we no longer call it for EL0 debug exceptions, and no longer
need to check user_mode(regs) as this is always false. For clarity
cortex_a76_erratum_1463225_debug_handler() is changed to return bool.

In the SVC path, the workaround is applied earlier, but this should have
no functional impact as exceptions are still masked. In the debug path
we run the fixup before explicitly disabling preemption, but we will not
attempt to preempt before returning from the exception.

There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210202120341.28858-1-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

As we are about to change the way a VHE system boots, let's
provide the core helper, in the form of a stub hypercall that
enables VHE and replicates the full EL1 context at EL2, thanks
to EL1 and VHE-EL2 being extremely similar.

On exception return, the kernel carries on at EL2. Fancy!

Nothing calls this new hypercall yet, so no functional change.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-5-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

Turning the MMU on is a popular sport in the arm64 kernel, and
we do it more than once, or even twice. As we are about to add
even more, let's turn it into a macro.

No expected functional change.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-4-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

The arm64 kernel has long be able to use more than 39bit VAs.
Since day one, actually. Let's rewrite the offending comment.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-3-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

If someone happens to write the following code:

	b	1f
	init_el2_state	vhe
1:
	[...]

they will be in for a long debugging session, as the label "1f"
will be resolved *inside* the init_el2_state macro instead of
after it. Not really what one expects.

Instead, rewite the EL2 setup macros to use unambiguous labels,
thanks to the usual macro counter trick.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-2-maz@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

The erratum 1024718 affects Cortex-A55 r0p0 to r2p0. However
we apply the work around for r0p0 - r1p0. Unfortunately this
won't be fixed for the future revisions for the CPU. Thus
extend the work around for all versions of A55, to cover
for r2p0 and any future revisions.

Cc: stable@vger.kernel.org
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20210203230057.3961239-1-suzuki.poulose@arm.com
[will: Update Kconfig help text]
Signed-off-by: Will Deacon <will@kernel.org>

commit d8ed45c5 ("mmap locking API: use coccinelle to convert mmap_sem
rwsem call sites") has convertd down_read_trylock() to mmap_read_trylock().
But it forgot to update the relevant comment.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Link: https://lore.kernel.org/r/20210205090919.63382-1-linmiaohe@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

In a few places we don't have whitespace between macro parameters,
which makes them hard to read. This patch adds whitespace to clearly
separate the parameters.

In a few places we have unnecessary whitespace around unary operators,
which is confusing, This patch removes the unnecessary whitespace.
Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn>
Link: https://lore.kernel.org/r/1612403029-5011-1-git-send-email-daizhiyuan@phytium.com.cnSigned-off-by: Will Deacon <will@kernel.org>

Add a macro cond_yield that branches to a specified label when called if
the TIF_NEED_RESCHED flag is set and decreasing the preempt count would
make the task preemptible again, resulting in a schedule to occur. This
can be used by kernel mode SIMD code that keeps a lot of state in SIMD
registers, which would make chunking the input in order to perform the
cond_resched() check from C code disproportionately costly.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20210203113626.220151-2-ardb@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

If CONFIG_MMU is not set (e.g. m68k/m5272c3_defconfig):

    mm/nommu.c:1671:6: error: conflicting types for ‘filemap_map_pages’
     1671 | void filemap_map_pages(struct vm_fault *vmf,
	  |      ^~~~~~~~~~~~~~~~~
    In file included from mm/nommu.c:20:
    ./include/linux/mm.h:2578:19: note: previous declaration of ‘filemap_map_pages’ was here
     2578 | extern vm_fault_t filemap_map_pages(struct vm_fault *vmf,
	  |                   ^~~~~~~~~~~~~~~~~

The signature of filemap_map_pages() was changed, but the nommu
implementation wasn't updated.

Reported-by: noreply@ellerman.id.au
Fixes: f9ce0be7 ("mm: Cleanup faultaround and finish_fault() codepaths")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20210128100626.2257638-1-geert@linux-m68k.orgSigned-off-by: Will Deacon <will@kernel.org>

The fields of this struct are only ever read after being initialised, so
mark it 'const' before somebody tries to modify it again. GCC will then
complain (with an error) about modification of these fields after they
have been initialised, although LLVM currently allows them without even
a warning:

https://bugs.llvm.org/show_bug.cgi?id=48755

Hopefully, future versions of LLVM will emit a warning.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>

In preparation for const-ifying the anonymous struct field of
'struct vm_fault', ensure that it is initialised using designated
initialisers.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Will Deacon <will@kernel.org>

In preparation for const-ifying the anonymous struct field of
'struct vm_fault', rework __collapse_huge_page_swapin() to avoid
continuously updating vmf.address and instead populate a new
'struct vm_fault' on the stack for each page being processed.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>

Rather than modifying the 'address' field of the 'struct vm_fault'
passed to do_set_pte(), leave that to identify the real faulting address
and pass in the virtual address to be mapped by the new pte as a
separate argument.

This makes FAULT_FLAG_PREFAULT redundant, as a prefault entry can be
identified simply by comparing the new address parameter with the
faulting address, so remove the redundant flag at the same time.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>

'struct vm_fault' contains both information about the fault being
serviced alongside mutable fields contributing to the state of the
fault-handling logic. Unfortunately, the distinction between the two is
not clear-cut, and a number of callers end up manipulating the structure
temporarily before restoring it when returning.

Try to clean this up by moving the immutable fault information into an
anonymous struct, which will later be marked as 'const'. Ideally, the
'flags' field would be part of the new structure too, but it seems as
though the ->page_mkwrite() path is not ready for this yet.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/CAHk-=whYs9XsO88iqJzN6NC=D-dp2m0oYXuOoZ=eWnvv=5OA+w@mail.gmail.comSigned-off-by: Will Deacon <will@kernel.org>

On CPUs with hardware AF/DBM, initialising prefaulted PTEs as 'old'
improves vmscan behaviour and does not appear to introduce any overhead
elsewhere.

Implement arch_wants_old_prefaulted_pte() to return 'true' if we detect
hardware access flag support at runtime. This can be extended in future
based on MIDR matching if necessary.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>