These plt* and .text.ftrace_trampoline sections specified for arm64 have
non-zero addressses. Non-zero section addresses in a relocatable ELF would
confuse GDB when it tries to compute the section offsets and it ends up
printing wrong symbol addresses. Therefore, set them to zero, which mirrors
the change in commit 5d8591bc ("module: set ksymtab/kcrctab* section
addresses to 0x0").
Reported-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Shaoying Xu <shaoyi@amazon.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210216183234.GA23876@amazon.comSigned-off-by: Will Deacon <will@kernel.org>

in function create_dtb(), if fdt_open_into() fails, we need to vfree
buf before return.

Fixes: 52b2a8af ("arm64: kexec_file: load initrd and device-tree")
Cc: stable@vger.kernel.org # v5.0
Signed-off-by: qiuguorui1 <qiuguorui1@huawei.com>
Link: https://lore.kernel.org/r/20210218125900.6810-1-qiuguorui1@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

The Spectre-v4 workaround is re-configured when resuming from suspend,
as the firmware may have re-enabled the mitigation despite the user
previously asking for it to be disabled.

Enabling or disabling the workaround can result in an undefined
instruction exception on CPUs which implement PSTATE.SSBS but only allow
it to be configured by adjusting the SPSR on exception return. We handle
this by installing an 'undef hook' which effectively emulates the access.

Installing this hook requires us to take a couple of spinlocks both to
avoid corrupting the internal list of hooks but also to ensure that we
don't run into an unhandled exception. Unfortunately, when resuming from
suspend, we haven't yet called rcu_idle_exit() and so lockdep gets angry
about "suspicious RCU usage". In doing so, it tries to print a warning,
which leads it to get even more suspicious, this time about itself:

 |  rcu_scheduler_active = 2, debug_locks = 1
 |  RCU used illegally from extended quiescent state!
 |  1 lock held by swapper/0:
 |   #0: (logbuf_lock){-.-.}-{2:2}, at: vprintk_emit+0x88/0x198
 |
 |  Call trace:
 |   dump_backtrace+0x0/0x1d8
 |   show_stack+0x18/0x24
 |   dump_stack+0xe0/0x17c
 |   lockdep_rcu_suspicious+0x11c/0x134
 |   trace_lock_release+0xa0/0x160
 |   lock_release+0x3c/0x290
 |   _raw_spin_unlock+0x44/0x80
 |   vprintk_emit+0xbc/0x198
 |   vprintk_default+0x44/0x6c
 |   vprintk_func+0x1f4/0x1fc
 |   printk+0x54/0x7c
 |   lockdep_rcu_suspicious+0x30/0x134
 |   trace_lock_acquire+0xa0/0x188
 |   lock_acquire+0x50/0x2fc
 |   _raw_spin_lock+0x68/0x80
 |   spectre_v4_enable_mitigation+0xa8/0x30c
 |   __cpu_suspend_exit+0xd4/0x1a8
 |   cpu_suspend+0xa0/0x104
 |   psci_cpu_suspend_enter+0x3c/0x5c
 |   psci_enter_idle_state+0x44/0x74
 |   cpuidle_enter_state+0x148/0x2f8
 |   cpuidle_enter+0x38/0x50
 |   do_idle+0x1f0/0x2b4

Prevent these splats by running __cpu_suspend_exit() with RCU watching.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Suggested-by: "Paul E . McKenney" <paulmck@kernel.org>
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Fixes: c2876207 ("arm64: Rewrite Spectre-v4 mitigation code")
Cc: <stable@vger.kernel.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20210218140346.5224-1-will@kernel.orgSigned-off-by: Will Deacon <will@kernel.org>

vDSO build improvements.

* for-next/vdso:
  arm64: Support running gen_vdso_offsets.sh with BSD userland.
  arm64: do not descend to vdso directories twice

Cleanup to the AMU support code and initialisation rework to support
cpufreq drivers built as modules.

* for-next/topology:
  arm64: topology: Make AMUs work with modular cpufreq drivers
  arm64: topology: Reorder init_amu_fie() a bit
  arm64: topology: Avoid the have_policy check

Remove synthetic frame record from exception stack when entering from
userspace.

* for-next/stacktrace:
  arm64: remove EL0 exception frame record

Trivial cleanup to one of the MTE selftests.

* for-next/selftests:
  arm64: mte: style: Simplify bool comparison

Add support for the TRNG firmware call introduced by Arm spec DEN0098.

* for-next/rng:
  arm64: Add support for SMCCC TRNG entropy source
  firmware: smccc: Introduce SMCCC TRNG framework
  firmware: smccc: Add SMCCC TRNG function call IDs

Avoid calling arch_get_random_seed_long() from add_interrupt_randomness()
as this can result in a firmware call on some arm64 systems.

* for-next/random:
  random: avoid arch_get_random_seed_long() when collecting IRQ randomness

Perf and PMU updates including support for Cortex-A78 and the v8.3 SPE
extensions.

* for-next/perf:
  drivers/perf: Replace spin_lock_irqsave to spin_lock
  dt-bindings: arm: add Cortex-A78 binding
  arm64: perf: add support for Cortex-A78
  arm64: perf: Constify static attribute_group structs
  drivers/perf: Prevent forced unbinding of ARM_DMC620_PMU drivers
  perf/arm-cmn: Move IRQs when migrating context
  perf/arm-cmn: Fix PMU instance naming
  perf: Constify static struct attribute_group
  perf: hisi: Constify static struct attribute_group
  perf/imx_ddr: Constify static struct attribute_group
  perf: qcom: Constify static struct attribute_group
  drivers/perf: Add support for ARMv8.3-SPE

Miscellaneous arm64 changes for 5.12.

* for-next/misc:
  arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+
  arm64: vmlinux.ld.S: add assertion for tramp_pg_dir offset
  arm64: vmlinux.ld.S: add assertion for reserved_pg_dir offset
  arm64/ptdump:display the Linear Mapping start marker
  arm64: ptrace: Fix missing return in hw breakpoint code
  KVM: arm64: Move __hyp_set_vectors out of .hyp.text
  arm64: Include linux/io.h in mm/mmap.c
  arm64: cacheflush: Remove stale comment
  arm64: mm: Remove unused header file
  arm64/sparsemem: reduce SECTION_SIZE_BITS
  arm64/mm: Add warning for outside range requests in vmemmap_populate()
  arm64: Drop workaround for broken 'S' constraint with GCC 4.9

Significant steps along the road to leaving the MMU enabled during kexec
relocation.

* for-next/kexec:
  arm64: hibernate: add __force attribute to gfp_t casting
  arm64: kexec: arm64_relocate_new_kernel don't use x0 as temp
  arm64: kexec: arm64_relocate_new_kernel clean-ups and optimizations
  arm64: kexec: call kexec_image_info only once
  arm64: kexec: move relocation function setup
  arm64: trans_pgd: hibernate: idmap the single page that holds the copy page routines
  arm64: mm: Always update TCR_EL1 from __cpu_set_tcr_t0sz()
  arm64: trans_pgd: pass NULL instead of init_mm to *_populate functions
  arm64: trans_pgd: pass allocator trans_pgd_create_copy
  arm64: trans_pgd: make trans_pgd_map_page generic
  arm64: hibernate: move page handling function to new trans_pgd.c
  arm64: hibernate: variable pudp is used instead of pd4dp
  arm64: kexec: make dtb_mem always enabled

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

There is no need to do spin_lock_irqsave in context of hard IRQ, so
replace them with spin_lock.
Signed-off-by: Qi Liu <liuqi115@huawei.com>
Link: https://lore.kernel.org/r/1612863742-1551-1-git-send-email-liuqi115@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

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>

Similar to commit 28187dc8 ("ARM: 9025/1: Kconfig: CPU_BIG_ENDIAN
depends on !LD_IS_LLD"), ld.lld prior to 13.0.0 does not properly
support aarch64 big endian, leading to the following build error when
CONFIG_CPU_BIG_ENDIAN is selected:

ld.lld: error: unknown emulation: aarch64linuxb

This has been resolved in LLVM 13. To avoid errors like this, only allow
CONFIG_CPU_BIG_ENDIAN to be selected if using ld.bfd or ld.lld 13.0.0
and newer.

While we are here, the indentation of this symbol used spaces since its
introduction in commit a872013d ("arm64: kconfig: allow
CPU_BIG_ENDIAN to be selected"). Change it to tabs to be consistent with
kernel coding style.

Link: https://github.com/ClangBuiltLinux/linux/issues/380
Link: https://github.com/ClangBuiltLinux/linux/issues/1288
Link: https://github.com/llvm/llvm-project/commit/7605a9a009b5fa3bdac07e3131c8d82f6d08feb7
Link: https://github.com/llvm/llvm-project/commit/eea34aae2e74e9b6fbdd5b95f479bc7f397bf387Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20210209005719.803608-1-nathan@kernel.orgSigned-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>