MRS emulation gets triggered with exception class (0x00 or 0x18) eventually
calling the function emulate_mrs() which fetches the user space instruction
and analyses it's encodings (OP0, OP1, OP2, CRN, CRM, RT). The kernel tries
to emulate the given instruction looking into the encoding details. Going
forward these encodings can also be parsed from ESR_ELx.ISS fields without
requiring to fetch/decode faulting userspace instruction which can improve
performance. This factorizes emulate_mrs() function in a way that it can be
called directly with MRS encodings (OP0, OP1, OP2, CRN, CRM) for any given
target register which can then be used directly from 0x18 exception class.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Extracting target register from ESR.ISS encoding has already been required
at multiple instances. Just make it a macro definition and replace all the
existing use cases.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

There's no need to treat mismatched cache-line sizes reported by CTR_EL0
differently to any other mismatched fields that we treat as "STRICT" in
the cpufeature code. In both cases we need to trap and emulate EL0
accesses to the register, so drop ARM64_MISMATCHED_CACHE_LINE_SIZE and
rely on ARM64_MISMATCHED_CACHE_TYPE instead.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[catalin.marinas@arm.com: move ARM64_HAS_CNP in the empty cpucaps.h slot]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

We rely on cpufeature framework to detect and enable CNP so for KVM we
need to patch hyp to set CNP bit just before TTBR0_EL2 gets written.

For the guest we encode CNP bit while building vttbr, so we don't need
to bother with that in a world switch.
Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Common Not Private (CNP) is a feature of ARMv8.2 extension which
allows translation table entries to be shared between different PEs in
the same inner shareable domain, so the hardware can use this fact to
optimise the caching of such entries in the TLB.

CNP occupies one bit in TTBRx_ELy and VTTBR_EL2, which advertises to
the hardware that the translation table entries pointed to by this
TTBR are the same as every PE in the same inner shareable domain for
which the equivalent TTBR also has CNP bit set. In case CNP bit is set
but TTBR does not point at the same translation table entries for a
given ASID and VMID, then the system is mis-configured, so the results
of translations are UNPREDICTABLE.

For kernel we postpone setting CNP till all cpus are up and rely on
cpufeature framework to 1) patch the code which is sensitive to CNP
and 2) update TTBR1_EL1 with CNP bit set. TTBR1_EL1 can be
reprogrammed as result of hibernation or cpuidle (via __enable_mmu).
For these two cases we restore CnP bit via __cpu_suspend_exit().

There are a few cases we need to care of changes in TTBR0_EL1:
  - a switch to idmap
  - software emulated PAN

we rule out latter via Kconfig options and for the former we make
sure that CNP is set for non-zero ASIDs only.
Reviewed-by: James Morse <james.morse@arm.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
[catalin.marinas@arm.com: default y for CONFIG_ARM64_CNP]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Instructions for modifying the PSTATE fields which were not supported
in the older toolchains (e.g, PAN, UAO) are generated using macros.
We have so far used the normal sys_reg() helper for defining the PSTATE
fields. While this works fine, it is really difficult to correlate the
code with the Arm ARM definition.

As per Arm ARM, the PSTATE fields are defined only using Op1, Op2 fields,
with fixed values for Op0, CRn. Also the CRm field has been reserved
for the Immediate value for the instruction. So using the sys_reg()
looks quite confusing.

This patch cleans up the instruction helpers by bringing them
in line with the Arm ARM definitions to make it easier to correlate
code with the document. No functional changes.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

The bad_mode() handler is called if we encounter an uunknown exception,
with the expectation that the subsequent call to panic() will halt the
system. Unfortunately, if the exception calling bad_mode() is taken from
EL0, then the call to die() can end up killing the current user task and
calling schedule() instead of falling through to panic().

Remove the die() call altogether, since we really want to bring down the
machine in this "impossible" case.
Signed-off-by: Hari Vyas <hari.vyas@broadcom.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

force_signal_inject() is designed to send a fatal signal to userspace,
so WARN if the current pt_regs indicates a kernel context. This can
currently happen for the undefined instruction trap, so patch that up so
we always BUG() if we didn't have a handler.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

The cpu errata and feature enable callbacks are only called via their
respective arm64_cpu_capabilities structure and therefore shouldn't
exist in the global namespace.

Move the PAN, RAS and cache maintenance emulation enable callbacks into
the same files as their corresponding arm64_cpu_capabilities structures,
making them static in the process.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

When running without VHE, it is necessary to set SCTLR_EL2.DSSBS if SSBD
has been forcefully disabled on the kernel command-line.
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

On CPUs with support for PSTATE.SSBS, the kernel can toggle the SSBD
state without needing to call into firmware.

This patch hooks into the existing SSBD infrastructure so that SSBS is
used on CPUs that support it, but it's all made horribly complicated by
the very real possibility of big/little systems that don't uniformly
provide the new capability.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Rather than panic() when taking an undefined instruction exception from
EL1, allow a hook to be registered in case we want to emulate the
instruction, like we will for the SSBS PSTATE manipulation instructions.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Now that we're all merged nicely into mainline, there's no need to check
to see if PR_SPEC_STORE_BYPASS is defined.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Armv8.5 introduces a new PSTATE bit known as Speculative Store Bypass
Safe (SSBS) which can be used as a mitigation against Spectre variant 4.

Additionally, a CPU may provide instructions to manipulate PSTATE.SSBS
directly, so that userspace can toggle the SSBS control without trapping
to the kernel.

This patch probes for the existence of SSBS and advertise the new instructions
to userspace if they exist.
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

I was passing through and figuered I'd fix this up:

	featuer -> feature
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Peter Z asked me to justify the barrier usage in asm/tlbflush.h, but
actually that whole block comment needs to be rewritten.
Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

By selecting HAVE_RCU_TABLE_INVALIDATE, we can rely on tlb_flush() being
called if we fail to batch table pages for freeing. This in turn allows
us to postpone walk-cache invalidation until tlb_finish_mmu(), which
avoids lots of unnecessary DSBs and means we can shoot down the ASID if
the range is large enough.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Now that the core mmu_gather code keeps track of both the levels of page
table cleared and also whether or not these entries correspond to
intermediate entries, we can use this in our tlb_flush() callback to
reduce the number of invalidations we issue as well as their scope.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

If there's one thing the RCU-based table freeing doesn't need, it's more
ifdeffery.

Remove the redundant !CONFIG_HAVE_RCU_TABLE_FREE code, since this option
is unconditionally selected in our Kconfig.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

When we are unmapping intermediate page-table entries or huge pages, we
don't need to issue a TLBI instruction for every PAGE_SIZE chunk in the
VA range being unmapped.

Allow the invalidation stride to be passed to __flush_tlb_range(), and
adjust our "just nuke the ASID" heuristic to take this into account.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Add a comment to explain why we can't get away with last-level
invalidation in flush_tlb_range()
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Now that our walk-cache invalidation routines imply a DSB before the
invalidation, we no longer need one when we are clearing an entry during
unmap.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

__flush_tlb_[kernel_]pgtable() rely on set_pXd() having a DSB after
writing the new table entry and therefore avoid the barrier prior to the
TLBI instruction.

In preparation for delaying our walk-cache invalidation on the unmap()
path, move the DSB into the TLB invalidation routines.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

flush_tlb_kernel_range() is only ever used to invalidate last-level
entries, so we can restrict the scope of the TLB invalidation
instruction.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Current implementation of get/put_user_unsafe default to get/put_user
which toggle PAN before each access, despite having been told by the caller
that multiple accesses to user memory were about to happen.

Provide implementations for user_access_begin/end to turn PAN off/on and
implement unsafe accessors that assume PAN was already turned off.
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Being consistent in our capitalisation for page-table dumps helps when
grepping for things like "end".
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Unlike crc32c(), which is wired up to the crypto API internally so the
optimal driver is selected based on the platform's capabilities,
crc32_le() is implemented as a library function using a slice-by-8 table
based C implementation. Even though few of the call sites may be
bottlenecks, calling a time variant implementation with a non-negligible
D-cache footprint is a bit of a waste, given that ARMv8.1 and up mandates
support for the CRC32 instructions that were optional in ARMv8.0, but are
already widely available, even on the Cortex-A53 based Raspberry Pi.

So implement routines that use these instructions if available, and fall
back to the existing generic routines otherwise. The selection is based
on alternatives patching.

Note that this unconditionally selects CONFIG_CRC32 as a builtin. Since
CRC32 is relied upon by core functionality such as CONFIG_OF_FLATTREE,
this just codifies the status quo.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Add a CRC32 feature bit and wire it up to the CPU id register so we
will be able to use alternatives patching for CRC32 operations.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Allow architectures to drop in accelerated CRC32 routines by making
the crc32_le/__crc32c_le entry points weak, and exposing non-weak
aliases for them that may be used by the accelerated versions as
fallbacks in case the instructions they rely upon are not available.
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

As agreed on the list, merge in the core mmu_gather changes which allow
us to track the levels of page-table being cleared. We'll build on this
in our low-level flushing routines, and Nick and Peter also have plans
for other architectures.
Signed-off-by: Will Deacon <will.deacon@arm.com>

We recently had to debug a TLB invalidation problem on the munmap()
path, which was made more difficult than necessary because:

  (a) The MMU gather code had changed without people realising
  (b) Many people subtly misunderstood the operation of the MMU gather
      code and its interactions with RCU and arch-specific TLB invalidation
  (c) Untangling the intended behaviour involved educated guesswork and
      plenty of discussion

Hopefully, we can avoid getting into this mess again by designating a
cross-arch group of people to look after this code. It is not intended
that they will have a separate tree, but they at least provide a point
of contact for anybody working in this area and can co-ordinate any
proposed future changes to the internal API.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

In preparation for maintaining the mmu_gather code as its own entity,
move the implementation out of memory.c and into its own file.

Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

It is common for architectures with hugepage support to require only a
single TLB invalidation operation per hugepage during unmap(), rather than
iterating through the mapping at a PAGE_SIZE increment. Currently,
however, the level in the page table where the unmap() operation occurs
is not stored in the mmu_gather structure, therefore forcing
architectures to issue additional TLB invalidation operations or to give
up and over-invalidate by e.g. invalidating the entire TLB.

Ideally, we could add an interval rbtree to the mmu_gather structure,
which would allow us to associate the correct mapping granule with the
various sub-mappings within the range being invalidated. However, this
is costly in terms of book-keeping and memory management, so instead we
approximate by keeping track of the page table levels that are cleared
and provide a means to query the smallest granule required for invalidation.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Some architectures require different TLB invalidation instructions
depending on whether it is only the last-level of page table being
changed, or whether there are also changes to the intermediate
(directory) entries higher up the tree.

Add a new bit to the flags bitfield in struct mmu_gather so that the
architecture code can operate accordingly if it's the intermediate
levels being invalidated.
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

The inner workings of the mmu_gather-based TLB invalidation mechanism
are not relevant to nommu configurations, so guard them with an #ifdef.
This allows us to implement future functions using static inlines
without breaking the build.
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

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