The ARM Linux kernel handles the EABI syscall numbers as follows:

  0           - NR_SYSCALLS-1	: Invoke syscall via syscall table
  NR_SYSCALLS - 0xeffff		: -ENOSYS (to be allocated in future)
  0xf0000     - 0xf07ff		: Private syscall or -ENOSYS if not allocated
  > 0xf07ff			: SIGILL

Our compat code gets this wrong and ends up sending SIGILL in response
to all syscalls greater than NR_SYSCALLS which have a value greater
than 0x7ff in the bottom 16 bits.

Fix this by defining the end of the ARM private syscall region and
checking the syscall number against that directly. Update the comment
while we're at it.

Cc: <stable@vger.kernel.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Reported-by: NPi-Hsun Shih <pihsun@chromium.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Currently, <uapi/asm/sigcontext.h> provides common definitions for
describing SVE context structures that are also used by the ptrace
definitions in <uapi/asm/ptrace.h>.

For this reason, a #include of <asm/sigcontext.h> was added in
ptrace.h, but it this turns out that this can interact badly with
userspace code that tries to include ptrace.h on top of the libc
headers (which may provide their own shadow definitions for
sigcontext.h).

To make the headers easier for userspace to consume, this patch
bounces the common definitions into an __SVE_* namespace and moves
them to a backend header <uapi/asm/sve_context.h> that can be
included by the other headers as appropriate.  This should allow
ptrace.h to be used alongside libc's sigcontext.h (if any) without
ill effects.

This should make the situation unambiguous: <asm/sigcontext.h> is
the header to include for the sigframe-specific definitions, while
<asm/ptrace.h> is the header to include for ptrace-specific
definitions.

To avoid conflicting with existing usage, <asm/sigcontext.h>
remains the canonical way to get the common definitions for
SVE_VQ_MIN, sve_vq_from_vl() etc., both in userspace and in the
kernel: relying on these being defined as a side effect of
including just <asm/ptrace.h> was never intended to be safe.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

SVE_PT_REGS_OFFSET is supposed to indicate the offset for skipping
over the ptrace NT_ARM_SVE header (struct user_sve_header) to the
start of the SVE register data proper.

However, currently SVE_PT_REGS_OFFSET is defined in terms of struct
sve_context, which is wrong: that structure describes the SVE
header in the signal frame, not in the ptrace regset.

This patch fixes the definition to use the ptrace header structure
struct user_sve_header instead.

By good fortune, the two structures are the same size anyway, so
there is no functional or ABI change.
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

For DDRC PMU, each PMU counter is fixed-purpose. There is a mismatch
between perf list and driver definition on rw_chg event.
# perf list | grep chg
  hisi_sccl1_ddrc0/rnk_chg/                          [Kernel PMU event]
  hisi_sccl1_ddrc0/rw_chg/                           [Kernel PMU event]
But the register offset of rw_chg event is not defined in the driver,
meanwhile bnk_chg register offset is mis-defined, let's fixup it.

Fixes: 904dcf03 ("perf: hisi: Add support for HiSilicon SoC DDRC PMU driver")
Cc: stable@vger.kernel.org
Cc: John Garry <john.garry@huawei.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reported-by: NWeijian Huang <huangweijian4@hisilicon.com>
Signed-off-by: NShaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Use the standard obj-$(CONFIG_...) syntex. The behavior is still the
same.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When KASLR is enabled (CONFIG_RANDOMIZE_BASE=y), the top 4K of kernel
virtual address space may be mapped to physical addresses despite being
reserved for ERR_PTR values.

Fix the randomization of the linear region so that we avoid mapping the
last page of the virtual address space.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Nliyueyi <liyueyi@live.com>
[will: rewrote commit message; merged in suggestion from Ard]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

It turns out the dt-probing part of this wasn't tested properly after it
was merged. commit 3aa0582f ("of: platform: populate /firmware/ node
from of_platform_default_populate_init()") changed the core-code to
generate the platform devices, meaning the driver's attempt fails, and it
bails out.

Fix this by removing the manual platform-device creation for DT systems,
core code has always done this for us.

CC: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

After finding a "firmware" dt node arm_sdei tries to match it's
compatible string with it. To do so it's calling of_find_matching_node()
which already takes care of decreasing the refcount on the "firmware"
node. We are then incorrectly decreasing the refcount on that node
again.

This patch removes the unwarranted call to of_node_put().
Signed-off-by: NNicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: NJames Morse <james.morse@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

In commit:

  3b714275 ("arm64: convert native/compat syscall entry to C")

... we moved the syscall invocation code from assembly to C, but left
behind a number of register aliases which are now unused.

Let's remove them before they confuse someone.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

For arm64: updates for 4.21, there is a compilation error:
arch/arm64/kernel/head.S: Assembler messages:
arch/arm64/kernel/head.S:824: Error: missing ')'
arch/arm64/kernel/head.S:824: Error: missing ')'
arch/arm64/kernel/head.S:824: Error: missing ')'
arch/arm64/kernel/head.S:824: Error: unexpected characters following instruction at operand 2 -- `mov x2,#(2)|(2U<<(8))'
scripts/Makefile.build:391: recipe for target 'arch/arm64/kernel/head.o' failed
make[1]: *** [arch/arm64/kernel/head.o] Error 1
GCC version is gcc (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.10) 5.4.0 20160609

Let's fix it using the UL() macro.

Fixes: 66f16a24 ("arm64: smp: Rework early feature mismatched detection")
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Tested-by: NJohn Stultz <john.stultz@linaro.org>
Signed-off-by: NShaokun Zhang <zhangshaokun@hisilicon.com>
[will: consistent use of UL() for all shifts in asm constants]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When debug with kaslr, it is sometimes necessary to have PHYS_OFFSET to
perform linear virtual address to physical address translation.
Sometimes we're debugging with only few information such as a kernel log
and a symbol file, print PHYS_OFFSET in dump_kernel_offset() for that case.

Tested by:
echo c > /proc/sysrq-trigger
[   11.996161] SMP: stopping secondary CPUs
[   11.996732] Kernel Offset: 0x2522200000 from 0xffffff8008000000
[   11.996881] PHYS_OFFSET: 0xffffffeb40000000

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NMiles Chen <miles.chen@mediatek.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Using shifts directly is error-prone and can cause inadvertent sign
extensions or build problems with older versions of binutils.

Consistent use of the _BITUL() macro makes these problems disappear.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Open-coding the pointer-auth HWCAPs is a mess and can be avoided by
reusing the multi-cap logic from the CPU errata framework.

Move the multi_entry_cap_matches code to cpufeature.h and reuse it for
the pointer auth HWCAPs.
Reviewed-by: NSuzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

We can easily avoid defining the two meta-capabilities for the address
and generic keys, so remove them and instead just check both of the
architected and impdef capabilities when determining the level of system
support.
Reviewed-by: NSuzuki Poulose <suzuki.poulose@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Now that we've added code to support pointer authentication, add some
documentation so that people can figure out if/how to use it.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: NRamana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Andrew Jones <drjones@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

We don't need to get at the per-thread keys from assembly at all, so
they can live alongside the rest of the per-thread register state in
thread_struct instead of thread_info.

This will also allow straighforward whitelisting of the keys for
hardened usercopy should we expose them via a ptrace request later on.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Now that all the necessary bits are in place for userspace, add the
necessary Kconfig logic to allow this to be enabled.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Add an arm64-specific prctl to allow a thread to reinitialize its
pointer authentication keys to random values. This can be useful when
exec() is not used for starting new processes, to ensure that different
processes still have different keys.
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When the kernel is unwinding userspace callchains, we can't expect that
the userspace consumer of these callchains has the data necessary to
strip the PAC from the stored LR.

This patch has the kernel strip the PAC from user stackframes when the
in-kernel unwinder is used. This only affects the LR value, and not the
FP.

This only affects the in-kernel unwinder. When userspace performs
unwinding, it is up to userspace to strip PACs as necessary (which can
be determined from DWARF information).
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

When pointer authentication is in use, data/instruction pointers have a
number of PAC bits inserted into them. The number and position of these
bits depends on the configured TCR_ELx.TxSZ and whether tagging is
enabled. ARMv8.3 allows tagging to differ for instruction and data
pointers.

For userspace debuggers to unwind the stack and/or to follow pointer
chains, they need to be able to remove the PAC bits before attempting to
use a pointer.

This patch adds a new structure with masks describing the location of
the PAC bits in userspace instruction and data pointers (i.e. those
addressable via TTBR0), which userspace can query via PTRACE_GETREGSET.
By clearing these bits from pointers (and replacing them with the value
of bit 55), userspace can acquire the PAC-less versions.

This new regset is exposed when the kernel is built with (user) pointer
authentication support, and the address authentication feature is
enabled. Otherwise, the regset is hidden.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[will: Fix to use vabits_user instead of VA_BITS and rename macro]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

This patch adds basic support for pointer authentication, allowing
userspace to make use of APIAKey, APIBKey, APDAKey, APDBKey, and
APGAKey. The kernel maintains key values for each process (shared by all
threads within), which are initialised to random values at exec() time.

The ID_AA64ISAR1_EL1.{APA,API,GPA,GPI} fields are exposed to userspace,
to describe that pointer authentication instructions are available and
that the kernel is managing the keys. Two new hwcaps are added for the
same reason: PACA (for address authentication) and PACG (for generic
authentication).
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Tested-by: NAdam Wallis <awallis@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
[will: Fix sizeof() usage and unroll address key initialisation]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

So that we can dynamically handle the presence of pointer authentication
functionality, wire up probing code in cpufeature.c.

From ARMv8.3 onwards, ID_AA64ISAR1 is no longer entirely RES0, and now
has four fields describing the presence of pointer authentication
functionality:

* APA - address authentication present, using an architected algorithm
* API - address authentication present, using an IMP DEF algorithm
* GPA - generic authentication present, using an architected algorithm
* GPI - generic authentication present, using an IMP DEF algorithm

This patch checks for both address and generic authentication,
separately. It is assumed that if all CPUs support an IMP DEF algorithm,
the same algorithm is used across all CPUs.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

To allow EL0 (and/or EL1) to use pointer authentication functionality,
we must ensure that pointer authentication instructions and accesses to
pointer authentication keys are not trapped to EL2.

This patch ensures that HCR_EL2 is configured appropriately when the
kernel is booted at EL2. For non-VHE kernels we set HCR_EL2.{API,APK},
ensuring that EL1 can access keys and permit EL0 use of instructions.
For VHE kernels host EL0 (TGE && E2H) is unaffected by these settings,
and it doesn't matter how we configure HCR_EL2.{API,APK}, so we don't
bother setting them.

This does not enable support for KVM guests, since KVM manages HCR_EL2
itself when running VMs.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Acked-by: NChristoffer Dall <christoffer.dall@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: NWill Deacon <will.deacon@arm.com>

In subsequent patches we're going to expose ptrauth to the host kernel
and userspace, but things are a bit trickier for guest kernels. For the
time being, let's hide ptrauth from KVM guests.

Regardless of how well-behaved the guest kernel is, guest userspace
could attempt to use ptrauth instructions, triggering a trap to EL2,
resulting in noise from kvm_handle_unknown_ec(). So let's write up a
handler for the PAC trap, which silently injects an UNDEF into the
guest, as if the feature were really missing.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: NAndrew Jones <drjones@redhat.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: NWill Deacon <will.deacon@arm.com>

In KVM we define the configuration of HCR_EL2 for a VHE HOST in
HCR_HOST_VHE_FLAGS, but we don't have a similar definition for the
non-VHE host flags, and open-code HCR_RW. Further, in head.S we
open-code the flags for VHE and non-VHE configurations.

In future, we're going to want to configure more flags for the host, so
lets add a HCR_HOST_NVHE_FLAGS defintion, and consistently use both
HCR_HOST_VHE_FLAGS and HCR_HOST_NVHE_FLAGS in the kvm code and head.S.

We now use mov_q to generate the HCR_EL2 value, as we use when
configuring other registers in head.S.
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Reviewed-by: NChristoffer Dall <christoffer.dall@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvmarm@lists.cs.columbia.edu
Signed-off-by: NWill Deacon <will.deacon@arm.com>

The ARMv8.3 pointer authentication extension adds:

* New fields in ID_AA64ISAR1 to report the presence of pointer
  authentication functionality.

* New control bits in SCTLR_ELx to enable this functionality.

* New system registers to hold the keys necessary for this
  functionality.

* A new ESR_ELx.EC code used when the new instructions are affected by
  configurable traps

This patch adds the relevant definitions to <asm/sysreg.h> and
<asm/esr.h> for these, to be used by subsequent patches.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

To make it clear which exceptions can't be taken to EL1 or EL2, add
comments next to the ESR_ELx_EC_* macro definitions.
Reviewed-by: NRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: NKristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Although the upper 32 bits of the PMEVTYPER<n>_EL0 registers are RES0,
we should treat the EXCLUDE_EL* bit definitions as unsigned so that we
avoid accidentally sign-extending the privilege filtering bit (bit 31)
into the upper half of the register.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

While the CSV3 field of the ID_AA64_PFR0 CPU ID register can be checked
to see if a CPU is susceptible to Meltdown and therefore requires kpti
to be enabled, existing CPUs do not implement this field.

We therefore whitelist all unaffected Cortex-A CPUs that do not implement
the CSV3 field.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Merge in arm64 perf and PMU driver updates, including support for the
system/uncore PMU in the ThunderX2 platform.

This enables the use of per-task stack canary values if GCC has
support for emitting the stack canary reference relative to the
value of sp_el0, which holds the task struct pointer in the arm64
kernel.

The $(eval) extends KBUILD_CFLAGS at the moment the make rule is
applied, which means asm-offsets.o (which we rely on for the offset
value) is built without the arguments, and everything built afterwards
has the options set.
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Wire up the basic support for hot-adding memory. Since memory hotplug
is fairly tightly coupled to sparsemem, we tweak pfn_valid() to also
cross-check the presence of a section in the manner of the generic
implementation, before falling back to memblock to check for no-map
regions within a present section as before. By having arch_add_memory(()
create the linear mapping first, this then makes everything work in the
way that __add_section() expects.

We expect hotplug to be ACPI-driven, so the swapper_pg_dir updates
should be safe from races by virtue of the global device hotplug lock.
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Commit 959bf2fd ("arm64: percpu: Rewrite per-cpu ops to allow use of
LSE atomics") introduced alternative code sequences for the arm64 percpu
atomics, so that the LSE instructions can be patched in at runtime if
they are supported by the CPU.

Unfortunately, when patching in the LSE sequence for a value-returning
pcpu atomic, the argument registers are the wrong way round. The
implementation of this_cpu_add_return() therefore ends up adding
uninitialised stack to the percpu variable and returning garbage.

As it turns out, there aren't very many users of the value-returning
percpu atomics in mainline and we only spotted this due to a failure in
the kprobes selftests. In this case, when attempting to single-step over
the out-of-line instruction slot, the debug monitors would not be
enabled because calling this_cpu_inc_return() on the kernel debug
monitor refcount would fail to detect the transition from 0. We would
consequently execute past the slot and take an undefined instruction
exception from the kernel, resulting in a BUG:

 | kernel BUG at arch/arm64/kernel/traps.c:421!
 | PREEMPT SMP
 | pc : do_undefinstr+0x268/0x278
 | lr : do_undefinstr+0x124/0x278
 | Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
 | Call trace:
 |  do_undefinstr+0x268/0x278
 |  el1_undef+0x10/0x78
 |  0xffff00000803c004
 |  init_kprobes+0x150/0x180
 |  do_one_initcall+0x74/0x178
 |  kernel_init_freeable+0x188/0x224
 |  kernel_init+0x10/0x100
 |  ret_from_fork+0x10/0x1c

Fix the argument order to get the value-returning pcpu atomics working
correctly when implemented using the LSE instructions.
Reported-by: NCatalin Marinas <catalin.marinas@arm.com>
Tested-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

While we can export symbols from assembly files, CONFIG_MODVERIONS requires C
declarations of anyhting that's exported.

Let's account for this as other architectures do by placing these declarations
in <asm/asm-prototypes.h>, which kbuild will automatically use to generate
modversion information for assembly files.

Since we already define most prototypes in existing headers, we simply need to
include those headers in <asm/asm-prototypes.h>, and don't need to duplicate
these.
Reviewed-by: NRobin Murphy <robin.murphy@arm.com>
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

With the introduction of 52-bit virtual addressing for userspace, we are
now in a position where the virtual addressing capability of userspace
may exceed that of the kernel. Consequently, the VA_BITS definition
cannot be used blindly, since it reflects only the size of kernel
virtual addresses.

This patch introduces MAX_USER_VA_BITS which is either VA_BITS or 52
depending on whether 52-bit virtual addressing has been configured at
build time, removing a few places where the 52 is open-coded based on
explicit CONFIG_ guards.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

In some randconfig builds, the new CONFIG_ARM64_USER_VA_BITS_52
triggered a build failure:

arch/arm64/mm/proc.S:287: Error: immediate out of range

As it turns out, we were incorrectly setting PGTABLE_LEVELS here,
lacking any other default value.
This fixes the calculation of CONFIG_PGTABLE_LEVELS to consider
all combinations again.

Fixes: 68d23da4 ("arm64: Kconfig: Re-jig CONFIG options for 52-bit VA")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Commit 39624469 ("arm64: preempt: Provide our own implementation of
asm/preempt.h") extended the preempt count field in struct thread_info
to 64 bits, so that it consists of a 32-bit count plus a 32-bit flag
indicating whether or not the current task needs rescheduling.

Whilst the asm-offsets definition of TSK_TI_PREEMPT was updated to point
to this new field, the assembly usage was left untouched meaning that a
32-bit load from TSK_TI_PREEMPT on a big-endian machine actually returns
the reschedule flag instead of the count.

Whilst we could fix this by pointing TSK_TI_PREEMPT at the count field,
we're actually better off reworking the two assembly users so that they
operate on the whole 64-bit value in favour of inspecting the thread
flags separately in order to determine whether a reschedule is needed.
Acked-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Reported-by: N"kernelci.org bot" <bot@kernelci.org>
Tested-by: NKevin Hilman <khilman@baylibre.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

This is needed for compilation in some configurations that don't
include it implicitly:

arch/arm64/kernel/machine_kexec_file.c: In function 'arch_kimage_file_post_load_cleanup':
arch/arm64/kernel/machine_kexec_file.c:37:2: error: implicit declaration of function 'vfree'; did you mean 'kvfree'? [-Werror=implicit-function-declaration]

Fixes: 52b2a8af ("arm64: kexec_file: load initrd and device-tree")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

TASK_SIZE is defined using the vabits_user variable for 64-bit tasks,
so ensure that this variable is exported to modules to avoid the
following build breakage with allmodconfig:

 | ERROR: "vabits_user" [lib/test_user_copy.ko] undefined!
 | ERROR: "vabits_user" [drivers/misc/lkdtm/lkdtm.ko] undefined!
 | ERROR: "vabits_user" [drivers/infiniband/hw/mlx5/mlx5_ib.ko] undefined!
Signed-off-by: NWill Deacon <will.deacon@arm.com>

Merge in kexec_file_load() support from Akashi Takahiro.