Now that the early kernel mapping is created with all the right
attributes and segment boundaries, there is no longer a need to recreate
it and switch to it. This also means we no longer have to copy the kasan
shadow or some parts of the fixmap from one set of page tables to the
other.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-68-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In preparation for moving the first assignment of arm64_use_ng_mappings
to an earlier stage in the boot, ensure that kaslr_requires_kpti() is
accessible without relying on the core kernel's view on whether or not
KASLR is enabled. So make it a static inline, and move the
kaslr_enabled() check out of it and into the callers, one of which will
disappear in a subsequent patch.
Once/when support for the obsolete ThunderX 1 platform is dropped, this
check reduces to a E0PD feature check on the local CPU.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-61-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In arm64_kernel_unmapped_at_el0() we use cpus_have_const_cap() to check
for ARM64_UNMAP_KERNEL_AT_EL0, but this is only necessary so that
arm64_get_bp_hardening_vector() and this_cpu_set_vectors() can run prior
to alternatives being patched. Otherwise this is not necessary and
alternative_has_cap_*() would be preferable.
For historical reasons, cpus_have_const_cap() is more complicated than
it needs to be. Before cpucaps are finalized, it will perform a bitmap
test of the system_cpucaps bitmap, and once cpucaps are finalized it
will use an alternative branch. This used to be necessary to handle some
race conditions in the window between cpucap detection and the
subsequent patching of alternatives and static branches, where different
branches could be out-of-sync with one another (or w.r.t. alternative
sequences). Now that we use alternative branches instead of static
branches, these are all patched atomically w.r.t. one another, and there
are only a handful of cases that need special care in the window between
cpucap detection and alternative patching.
Due to the above, it would be nice to remove cpus_have_const_cap(), and
migrate callers over to alternative_has_cap_*(), cpus_have_final_cap(),
or cpus_have_cap() depending on when their requirements. This will
remove redundant instructions and improve code generation, and will make
it easier to determine how each callsite will behave before, during, and
after alternative patching.
The ARM64_UNMAP_KERNEL_AT_EL0 cpucap is a system-wide feature that is
detected and patched before any translation tables are created for
userspace. In the window between detecting the ARM64_UNMAP_KERNEL_AT_EL0
cpucap and patching alternatives, most users of
arm64_kernel_unmapped_at_el0() do not need to know that the cpucap has
been detected:
* As KVM is initialized after cpucaps are finalized, no usaef of
arm64_kernel_unmapped_at_el0() in the KVM code is reachable during
this window.
* The arm64_mm_context_get() function in arch/arm64/mm/context.c is only
called after the SMMU driver is brought up after alternatives have
been patched. Thus this can safely use cpus_have_final_cap() or
alternative_has_cap_*().
Similarly the asids_update_limit() function is called after
alternatives have been patched as an arch_initcall, and this can
safely use cpus_have_final_cap() or alternative_has_cap_*().
Similarly we do not expect an ASID rollover to occur between cpucaps
being detected and patching alternatives. Thus
set_reserved_asid_bits() can safely use cpus_have_final_cap() or
alternative_has_cap_*().
* The __tlbi_user() and __tlbi_user_level() macros are not used during
this window, and only need to invalidate additional entries once
userspace translation tables have been active on a CPU. Thus these can
safely use alternative_has_cap_*().
* The xen_kernel_unmapped_at_usr() function is not used during this
window as it is only used in a late_initcall. Thus this can safely use
cpus_have_final_cap() or alternative_has_cap_*().
* The arm64_get_meltdown_state() function is not used during this
window. It only used by arm64_get_meltdown_state() and KVM code, both
of which are only used after cpucaps have been finalized. Thus this
can safely use cpus_have_final_cap() or alternative_has_cap_*().
* The tls_thread_switch() uses arm64_kernel_unmapped_at_el0() as an
optimization to avoid zeroing tpidrro_el0 when KPTI is enabled
and this will be trampled by the KPTI trampoline. It doesn't matter if
this continues to zero the register during the window between
detecting the cpucap and patching alternatives, so this can safely use
alternative_has_cap_*().
* The sdei_arch_get_entry_point() and do_sdei_event() functions aren't
reachable at this time as the SDEI driver is registered later by
acpi_init() -> acpi_ghes_init() -> sdei_init(), where acpi_init is a
subsys_initcall. Thus these can safely use cpus_have_final_cap() or
alternative_has_cap_*().
* The uses under drivers/ aren't reachable at this time as the drivers
are registered later:
- TRBE is registered via module_init()
- SMMUv3 is registred via module_driver()
- SPE is registred via module_init()
* The arm64_get_bp_hardening_vector() and this_cpu_set_vectors()
functions need to run on boot CPUs prior to patching alternatives.
As these are only called during the onlining of a CPU, it's fine to
perform a system_cpucaps bitmap test using cpus_have_cap().
This patch modifies this_cpu_set_vectors() to use cpus_have_cap(), and
replaced all other use of cpus_have_const_cap() with
alternative_has_cap_unlikely(), which will avoid generating code to test
the system_cpucaps bitmap and should be better for all subsequent calls
at runtime. The ARM64_UNMAP_KERNEL_AT_EL0 cpucap is added to
cpucap_is_possible() so that code can be elided entirely when this is
not possible.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Over time, arm64's mm/mmu.c has become increasingly large and painful to
navigate. Move the fixmap code to its own file where it can be understood in
isolation.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20230406152759.4164229-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
asm/mmu.h refers to cpus_have_const_cap() in the definition of
arm64_kernel_unmapped_at_el0() so include asm/cpufeature.h directly
rather than force all users of the header to do it themselves.
Signed-off-by: Will Deacon <will@kernel.org>
Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211202171048.26924-2-will@kernel.org
When switching to an 'mm_struct' for the first time following an ASID
rollover, a new ASID may be allocated and assigned to 'mm->context.id'.
This reassignment can happen concurrently with other operations on the
mm, such as unmapping pages and subsequently issuing TLB invalidation.
Consequently, we need to ensure that (a) accesses to 'mm->context.id'
are atomic and (b) all page-table updates made prior to a TLBI using the
old ASID are guaranteed to be visible to CPUs running with the new ASID.
This was found by inspection after reviewing the VMID changes from
Shameer but it looks like a real (yet hard to hit) bug.
Cc: <stable@vger.kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Jade Alglave <jade.alglave@arm.com>
Cc: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Signed-off-by: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210806113109.2475-2-will@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The BP hardening helpers are an integral part of the Spectre-v2
mitigation, so move them into asm/spectre.h and inline the
arm64_get_bp_hardening_data() function at the same time.
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20201113113847.21619-6-will@kernel.org
Fix and subsequently rewrite Spectre mitigations, including the addition
of support for PR_SPEC_DISABLE_NOEXEC.
(Will Deacon and Marc Zyngier)
* for-next/ghostbusters: (22 commits)
arm64: Add support for PR_SPEC_DISABLE_NOEXEC prctl() option
arm64: Pull in task_stack_page() to Spectre-v4 mitigation code
KVM: arm64: Allow patching EL2 vectors even with KASLR is not enabled
arm64: Get rid of arm64_ssbd_state
KVM: arm64: Convert ARCH_WORKAROUND_2 to arm64_get_spectre_v4_state()
KVM: arm64: Get rid of kvm_arm_have_ssbd()
KVM: arm64: Simplify handling of ARCH_WORKAROUND_2
arm64: Rewrite Spectre-v4 mitigation code
arm64: Move SSBD prctl() handler alongside other spectre mitigation code
arm64: Rename ARM64_SSBD to ARM64_SPECTRE_V4
arm64: Treat SSBS as a non-strict system feature
arm64: Group start_thread() functions together
KVM: arm64: Set CSV2 for guests on hardware unaffected by Spectre-v2
arm64: Rewrite Spectre-v2 mitigation code
arm64: Introduce separate file for spectre mitigations and reporting
arm64: Rename ARM64_HARDEN_BRANCH_PREDICTOR to ARM64_SPECTRE_V2
KVM: arm64: Simplify install_bp_hardening_cb()
KVM: arm64: Replace CONFIG_KVM_INDIRECT_VECTORS with CONFIG_RANDOMIZE_BASE
arm64: Remove Spectre-related CONFIG_* options
arm64: Run ARCH_WORKAROUND_2 enabling code on all CPUs
...
For better or worse, the world knows about "Spectre" and not about
"Branch predictor hardening". Rename ARM64_HARDEN_BRANCH_PREDICTOR to
ARM64_SPECTRE_V2 as part of moving all of the Spectre mitigations into
their own little corner.
Signed-off-by: Will Deacon <will@kernel.org>
The spectre mitigations are too configurable for their own good, leading
to confusing logic trying to figure out when we should mitigate and when
we shouldn't. Although the plethora of command-line options need to stick
around for backwards compatibility, the default-on CONFIG options that
depend on EXPERT can be dropped, as the mitigations only do anything if
the system is vulnerable, a mitigation is available and the command-line
hasn't disabled it.
Remove CONFIG_HARDEN_BRANCH_PREDICTOR and CONFIG_ARM64_SSBD in favour of
enabling this code unconditionally.
Signed-off-by: Will Deacon <will@kernel.org>
To enable address space sharing with the IOMMU, introduce
arm64_mm_context_get() and arm64_mm_context_put(), that pin down a
context and ensure that it will keep its ASID after a rollover. Export
the symbols to let the modular SMMUv3 driver use them.
Pinning is necessary because a device constantly needs a valid ASID,
unlike tasks that only require one when running. Without pinning, we would
need to notify the IOMMU when we're about to use a new ASID for a task,
and it would get complicated when a new task is assigned a shared ASID.
Consider the following scenario with no ASID pinned:
1. Task t1 is running on CPUx with shared ASID (gen=1, asid=1)
2. Task t2 is scheduled on CPUx, gets ASID (1, 2)
3. Task tn is scheduled on CPUy, a rollover occurs, tn gets ASID (2, 1)
We would now have to immediately generate a new ASID for t1, notify
the IOMMU, and finally enable task tn. We are holding the lock during
all that time, since we can't afford having another CPU trigger a
rollover. The IOMMU issues invalidation commands that can take tens of
milliseconds.
It gets needlessly complicated. All we wanted to do was schedule task tn,
that has no business with the IOMMU. By letting the IOMMU pin tasks when
needed, we avoid stalling the slow path, and let the pinning fail when
we're out of shareable ASIDs.
After a rollover, the allocator expects at least one ASID to be available
in addition to the reserved ones (one per CPU). So (NR_ASIDS - NR_CPUS -
1) is the maximum number of ASIDs that can be shared with the IOMMU.
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20200918101852.582559-5-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>
hyp-entry.S contains implementation of KVM hyp vectors. This code is mostly
shared between VHE/nVHE, therefore compile it under both VHE and nVHE build
rules. nVHE-specific host HVC handler is hidden behind __KVM_NVHE_HYPERVISOR__.
Adjust code which selects which KVM hyp vecs to install to choose the correct
VHE/nVHE symbol.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-7-dbrazdil@google.com
In preparation for removing the signal trampoline from the compat vDSO,
allow the sigpage and the compat vDSO to co-exist.
For the moment the vDSO signal trampoline will still be used when built.
Subsequent patches will move to the sigpage consistently.
Acked-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
- In-kernel Pointer Authentication support (previously only offered to
user space).
- ARM Activity Monitors (AMU) extension support allowing better CPU
utilisation numbers for the scheduler (frequency invariance).
- Memory hot-remove support for arm64.
- Lots of asm annotations (SYM_*) in preparation for the in-kernel
Branch Target Identification (BTI) support.
- arm64 perf updates: ARMv8.5-PMU 64-bit counters, refactoring the PMU
init callbacks, support for new DT compatibles.
- IPv6 header checksum optimisation.
- Fixes: SDEI (software delegated exception interface) double-lock on
hibernate with shared events.
- Minor clean-ups and refactoring: cpu_ops accessor, cpu_do_switch_mm()
converted to C, cpufeature finalisation helper.
- sys_mremap() comment explaining the asymmetric address untagging
behaviour.
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
"The bulk is in-kernel pointer authentication, activity monitors and
lots of asm symbol annotations. I also queued the sys_mremap() patch
commenting the asymmetry in the address untagging.
Summary:
- In-kernel Pointer Authentication support (previously only offered
to user space).
- ARM Activity Monitors (AMU) extension support allowing better CPU
utilisation numbers for the scheduler (frequency invariance).
- Memory hot-remove support for arm64.
- Lots of asm annotations (SYM_*) in preparation for the in-kernel
Branch Target Identification (BTI) support.
- arm64 perf updates: ARMv8.5-PMU 64-bit counters, refactoring the
PMU init callbacks, support for new DT compatibles.
- IPv6 header checksum optimisation.
- Fixes: SDEI (software delegated exception interface) double-lock on
hibernate with shared events.
- Minor clean-ups and refactoring: cpu_ops accessor,
cpu_do_switch_mm() converted to C, cpufeature finalisation helper.
- sys_mremap() comment explaining the asymmetric address untagging
behaviour"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (81 commits)
mm/mremap: Add comment explaining the untagging behaviour of mremap()
arm64: head: Convert install_el2_stub to SYM_INNER_LABEL
arm64: Introduce get_cpu_ops() helper function
arm64: Rename cpu_read_ops() to init_cpu_ops()
arm64: Declare ACPI parking protocol CPU operation if needed
arm64: move kimage_vaddr to .rodata
arm64: use mov_q instead of literal ldr
arm64: Kconfig: verify binutils support for ARM64_PTR_AUTH
lkdtm: arm64: test kernel pointer authentication
arm64: compile the kernel with ptrauth return address signing
kconfig: Add support for 'as-option'
arm64: suspend: restore the kernel ptrauth keys
arm64: __show_regs: strip PAC from lr in printk
arm64: unwind: strip PAC from kernel addresses
arm64: mask PAC bits of __builtin_return_address
arm64: initialize ptrauth keys for kernel booting task
arm64: initialize and switch ptrauth kernel keys
arm64: enable ptrauth earlier
arm64: cpufeature: handle conflicts based on capability
arm64: cpufeature: Move cpu capability helpers inside C file
...
* for-next/asm-annotations:
: Modernise arm64 assembly annotations
arm64: head: Convert install_el2_stub to SYM_INNER_LABEL
arm64: Mark call_smc_arch_workaround_1 as __maybe_unused
arm64: entry-ftrace.S: Fix missing argument for CONFIG_FUNCTION_GRAPH_TRACER=y
arm64: vdso32: Convert to modern assembler annotations
arm64: vdso: Convert to modern assembler annotations
arm64: sdei: Annotate SDEI entry points using new style annotations
arm64: kvm: Modernize __smccc_workaround_1_smc_start annotations
arm64: kvm: Modernize annotation for __bp_harden_hyp_vecs
arm64: kvm: Annotate assembly using modern annoations
arm64: kernel: Convert to modern annotations for assembly data
arm64: head: Annotate stext and preserve_boot_args as code
arm64: head.S: Convert to modern annotations for assembly functions
arm64: ftrace: Modernise annotation of return_to_handler
arm64: ftrace: Correct annotation of ftrace_caller assembly
arm64: entry-ftrace.S: Convert to modern annotations for assembly functions
arm64: entry: Additional annotation conversions for entry.S
arm64: entry: Annotate ret_from_fork as code
arm64: entry: Annotate vector table and handlers as code
arm64: crypto: Modernize names for AES function macros
arm64: crypto: Modernize some extra assembly annotations
Enabling KASLR forces the use of non-global page-table entries for kernel
mappings, as this is a decision that we have to make very early on before
mapping the kernel proper. When used in conjunction with the "kpti=off"
command-line option, it is possible to use non-global kernel mappings but
with the kpti trampoline disabled.
Since commit 09e3c22a86 ("arm64: Use a variable to store non-global
mappings decision"), arm64_kernel_unmapped_at_el0() reflects only the use of
non-global mappings and does not take into account whether the kpti
trampoline is enabled. This breaks context switching of the TPIDRRO_EL0
register for 64-bit tasks, where the clearing of the register is deferred to
the ret-to-user code, but it also breaks the ARM SPE PMU driver which
helpfully recommends passing "kpti=off" on the command line!
Report whether or not KPTI is actually enabled in
arm64_kernel_unmapped_at_el0() and check the 'arm64_use_ng_mappings' global
variable directly when determining the protection flags for kernel mappings.
Cc: Mark Brown <broonie@kernel.org>
Reported-by: Hongbo Yao <yaohongbo@huawei.com>
Tested-by: Hongbo Yao <yaohongbo@huawei.com>
Fixes: 09e3c22a86 ("arm64: Use a variable to store non-global mappings decision")
Signed-off-by: Will Deacon <will@kernel.org>
We have recently introduced new macros for annotating assembly symbols
for things that aren't C functions, SYM_CODE_START() and SYM_CODE_END(),
in an effort to clarify and simplify our annotations of assembly files.
Using these for __bp_harden_hyp_vecs is more involved than for most symbols
as this symbol is annotated quite unusually as rather than just have the
explicit symbol we define _start and _end symbols which we then use to
compute the length. This does not play at all nicely with the new style
macros. Since the size of the vectors is a known constant which won't vary
the simplest thing to do is simply to drop the separate _start and _end
symbols and just use a #define for the size.
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Commit 25b92693a1 ("arm64: mm: convert cpu_do_switch_mm() to C") added
a new use of the ASID() macro, so update the comment in asm/mmu.h which
reasons about why an atomic reload of 'mm->context.id.counter' is not
required.
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Refactor the code which checks to see if we need to use non-global
mappings to use a variable instead of checking with the CPU capabilities
each time, doing the initial check for KPTI early in boot before we
start allocating memory so we still avoid transitioning to non-global
mappings in common cases.
Since this variable always matches our decision about non-global
mappings this means we can also combine arm64_kernel_use_ng_mappings()
and arm64_unmap_kernel_at_el0() into a single function, the variable
simply stores the result and the decision code is elsewhere. We could
just have the users check the variable directly but having a function
makes it clear that these uses are read-only.
The result is that we simplify the code a bit and reduces the amount of
code executed at runtime.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Since E0PD is intended to fulfil the same role as KPTI we don't need to
use KPTI on CPUs where E0PD is available, we can rely on E0PD instead.
Change the check that forces KPTI on when KASLR is enabled to check for
E0PD before doing so, CPUs with E0PD are not expected to be affected by
meltdown so should not need to enable KPTI for other reasons.
Since E0PD is a system capability we will still enable KPTI if any of
the CPUs in the system lacks E0PD, this will rewrite any global mappings
that were established in systems where some but not all CPUs support
E0PD. We may transiently have a mix of global and non-global mappings
while booting since we use the local CPU when deciding if KPTI will be
required prior to completing CPU enumeration but any global mappings
will be converted to non-global ones when KPTI is applied.
KPTI can still be forced on from the command line if required.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
In preparation for integrating E0PD support with KASLR factor out the
checks for interaction between KASLR and KPTI done in boot context into
a new function kaslr_requires_kpti(), in the process clarifying the
distinction between what we do in boot context and what we do at
runtime.
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Currently in arm64, FDT is mapped to RO before it's passed to
early_init_dt_scan(). However, there might be some codes
(eg. commit "fdt: add support for rng-seed") that need to modify FDT
during init. Map FDT to RO after early fixups are done.
Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program is
distributed in the hope that it will be useful but without any
warranty without even the implied warranty of merchantability or
fitness for a particular purpose see the gnu general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The arm64 asm/memblock.h header exists only to provide a function
prototype for arm64_memblock_init(), which is called only from
setup_arch().
Move the declaration into mmu.h, where it can live alongside other
init functions such as paging_init() and bootmem_init() without the
need for its own special header file.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Since commit b89d82ef01 ("arm64: kpti: Avoid rewriting early page
tables when KASLR is enabled"), a kernel built with CONFIG_RANDOMIZE_BASE
can decide early whether to use non-global mappings by checking the
kaslr_offset().
A kernel built without CONFIG_RANDOMIZE_BASE, instead checks the
cpufeature static-key.
This leaves a gap where CONFIG_RANDOMIZE_BASE was enabled, no
kaslr seed was provided, but kpti was forced on using the cmdline
option.
When the decision is made late, kpti_install_ng_mappings() will re-write
the page tables, but arm64_kernel_use_ng_mappings()'s value does not
change as it only tests the cpufeature static-key if
CONFIG_RANDOMIZE_BASE is disabled.
This function influences PROT_DEFAULT via PTE_MAYBE_NG, and causes
pgattr_change_is_safe() to catch nG->G transitions when the unchanged
PROT_DEFAULT is used as part of PAGE_KERNEL_RO:
[ 1.942255] alternatives: patching kernel code
[ 1.998288] ------------[ cut here ]------------
[ 2.000693] kernel BUG at arch/arm64/mm/mmu.c:165!
[ 2.019215] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[ 2.020257] Modules linked in:
[ 2.020807] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc2 #51
[ 2.021917] Hardware name: linux,dummy-virt (DT)
[ 2.022790] pstate: 40000005 (nZcv daif -PAN -UAO)
[ 2.023742] pc : __create_pgd_mapping+0x508/0x6d0
[ 2.024671] lr : __create_pgd_mapping+0x500/0x6d0
[ 2.058059] Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
[ 2.059369] Call trace:
[ 2.059845] __create_pgd_mapping+0x508/0x6d0
[ 2.060684] update_mapping_prot+0x48/0xd0
[ 2.061477] mark_linear_text_alias_ro+0xdc/0xe4
[ 2.070502] smp_cpus_done+0x90/0x98
[ 2.071216] smp_init+0x100/0x114
[ 2.071878] kernel_init_freeable+0xd4/0x220
[ 2.072750] kernel_init+0x10/0x100
[ 2.073455] ret_from_fork+0x10/0x18
[ 2.075414] ---[ end trace 3572f3a7782292de ]---
[ 2.076389] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
If arm64_kernel_unmapped_at_el0() is true, arm64_kernel_use_ng_mappings()
should also be true.
Signed-off-by: James Morse <james.morse@arm.com>
CC: Ard Biesheuvel <ard.biesheuvel@linaro.org>
CC: John Garry <john.garry@huawei.com>
CC: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
A side effect of commit c55191e96c ("arm64: mm: apply r/o permissions
of VM areas to its linear alias as well") is that the linear map is
created with page granularity, which means that transitioning the early
page table from global to non-global mappings when enabling kpti can
take a significant amount of time during boot.
Given that most CPU implementations do not require kpti, this mainly
impacts KASLR builds where kpti is forcefully enabled. However, in these
situations we know early on that non-global mappings are required and
can avoid the use of global mappings from the beginning. The only gotcha
is Cavium erratum #27456, which we must detect based on the MIDR value
of the boot CPU.
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reported-by: John Garry <john.garry@huawei.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Since the address of swapper_pg_dir is fixed for a given kernel image,
it is an attractive target for manipulation via an arbitrary write. To
mitigate this we'd like to make it read-only by moving it into the
rodata section.
We require that swapper_pg_dir is at a fixed offset from tramp_pg_dir
and reserved_ttbr0, so these will also need to move into rodata.
However, swapper_pg_dir is allocated along with some transient page
tables used for boot which we do not want to move into rodata.
As a step towards this, this patch separates the boot-time page tables
into a new init_pg_dir, and reduces swapper_pg_dir to the single page it
needs to be. This allows us to retain the relationship between
swapper_pg_dir, tramp_pg_dir, and swapper_pg_dir, while cleanly
separating these from the boot-time page tables.
The init_pg_dir holds all of the pgd/pud/pmd/pte levels needed during
boot, and all of these levels will be freed when we switch to the
swapper_pg_dir, which is initialized by the existing code in
paging_init(). Since we start off on the init_pg_dir, we no longer need
to allocate a transient page table in paging_init() in order to ensure
that swapper_pg_dir isn't live while we initialize it.
There should be no functional change as a result of this patch.
Signed-off-by: Jun Yao <yaojun8558363@gmail.com>
Reviewed-by: James Morse <james.morse@arm.com>
[Mark: place init_pg_dir after BSS, fold mm changes, commit message]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
We're now ready to map our vectors in weird and wonderful locations.
On enabling ARM64_HARDEN_EL2_VECTORS, a vector slot gets allocated
if this hasn't been already done via ARM64_HARDEN_BRANCH_PREDICTOR
and gets mapped outside of the normal RAM region, next to the
idmap.
That way, being able to obtain VBAR_EL2 doesn't reveal the mapping
of the rest of the hypervisor code.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
We're about to need to allocate hardening slots from other parts
of the kernel (in order to support ARM64_HARDEN_EL2_VECTORS).
Turn the counter into an atomic_t and make it available to the
rest of the kernel. Also add BP_HARDEN_EL2_SLOTS as the number of
slots instead of the hardcoded 4...
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
When CONFIG_UNMAP_KERNEL_AT_EL0 is set the SDEI entry point and the rest
of the kernel may be unmapped when we take an event. If this may be the
case, use an entry trampoline that can switch to the kernel page tables.
We can't use the provided PSTATE to determine whether to switch page
tables as we may have interrupted the kernel's entry trampoline, (or a
normal-priority event that interrupted the kernel's entry trampoline).
Instead test for a user ASID in ttbr1_el1.
Save a value in regs->addr_limit to indicate whether we need to restore
the original ASID when returning from this event. This value is only used
by do_page_fault(), which we don't call with the SDEI regs.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Aliasing attacks against CPU branch predictors can allow an attacker to
redirect speculative control flow on some CPUs and potentially divulge
information from one context to another.
This patch adds initial skeleton code behind a new Kconfig option to
enable implementation-specific mitigations against these attacks for
CPUs that are affected.
Co-developed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
There are now a handful of open-coded masks to extract the ASID from a
TTBR value, so introduce a TTBR_ASID_MASK and use that instead.
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Allow explicit disabling of the entry trampoline on the kernel command
line (kpti=off) by adding a fake CPU feature (ARM64_UNMAP_KERNEL_AT_EL0)
that can be used to toggle the alternative sequences in our entry code and
avoid use of the trampoline altogether if desired. This also allows us to
make use of a static key in arm64_kernel_unmapped_at_el0().
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
In order for code such as TLB invalidation to operate efficiently when
the decision to map the kernel at EL0 is determined at runtime, this
patch introduces a helper function, arm64_kernel_unmapped_at_el0, to
determine whether or not the kernel is mapped whilst running in userspace.
Currently, this just reports the value of CONFIG_UNMAP_KERNEL_AT_EL0,
but will later be hooked up to a fake CPU capability using a static key.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
In preparation for separate kernel/user ASIDs, allocate them in pairs
for each mm_struct. The bottom bit distinguishes the two: if it is set,
then the ASID will map only userspace.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Currently mm->context.flags field uses thread_info flags which is not
the best idea for many reasons. For example, mm_context_t doesn't need
most of thread_info flags. And it would be difficult to add new mm-related
flag if needed because it may easily interfere with TIF ones.
To deal with it, the new MMCF_AARCH32 flag is introduced for
mm_context_t->flags, where MMCF prefix stands for mm_context_t flags.
Also, mm_context_t flag doesn't require atomicity and ordering of the
access, so using set/clear_bit() is replaced with simple masks.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
One important rule of thumb when desiging a secure software system is
that memory should never be writable and executable at the same time.
We mostly adhere to this rule in the kernel, except at boot time, when
regions may be mapped RWX until after we are done applying alternatives
or making other one-off changes.
For the alternative patching, we can improve the situation by applying
the fixups via the linear mapping, which is never mapped with executable
permissions. So map the linear alias of .text with RW- permissions
initially, and remove the write permissions as soon as alternative
patching has completed.
Reviewed-by: Laura Abbott <labbott@redhat.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
We need to decide in some cases like uprobe instruction analysis that
whether the current mm context belongs to a 32 bit task or 64 bit.
This patch has introduced an unsigned flag variable in mm_context_t.
Currently, we set and clear TIF_32BIT depending on the condition that
whether an elf binary load sets personality for 32 bit or 64 bit
respectively.
Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In preparation of adding support for contiguous PTE and PMD mappings,
let's replace 'block_mappings_allowed' with 'page_mappings_only', which
will be a more accurate description of the nature of the setting once we
add such contiguous mappings into the mix.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add a bool parameter 'allow_block_mappings' to create_pgd_mapping() and
the various helper functions that it descends into, to give the caller
control over whether block entries may be used to create the mapping.
The UEFI runtime mapping routines will use this to avoid creating block
entries that would need to split up into page entries when applying the
permissions listed in the Memory Attributes firmware table.
This also replaces the block_mappings_allowed() helper function that was
added for DEBUG_PAGEALLOC functionality, but the resulting code is
functionally equivalent (given that debug_page_alloc does not operate on
EFI page table entries anyway)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In order to extract NUMA information from the device tree, we need to
have the tree in its unflattened form.
Move the call to bootmem_init() in the tail of paging_init() into
setup_arch, and adjust header files so that its declaration is
visible.
Move the unflatten_device_tree() call between the calls to
paging_init() and bootmem_init(). Follow on patches add NUMA handling
to bootmem_init().
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Our current switch_mm implementation suffers from a number of problems:
(1) The ASID allocator relies on IPIs to synchronise the CPUs on a
rollover event
(2) Because of (1), we cannot allocate ASIDs with interrupts disabled
and therefore make use of a TIF_SWITCH_MM flag to postpone the
actual switch to finish_arch_post_lock_switch
(3) We run context switch with a reserved (invalid) TTBR0 value, even
though the ASID and pgd are updated atomically
(4) We take a global spinlock (cpu_asid_lock) during context-switch
(5) We use h/w broadcast TLB operations when they are not required
(e.g. in flush_context)
This patch addresses these problems by rewriting the ASID algorithm to
match the bitmap-based arch/arm/ implementation more closely. This in
turn allows us to remove much of the complications surrounding switch_mm,
including the ugly thread flag.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Commit 68234df4ea ("arm64: kill flush_cache_all()") removed
soft_reset() from the kernel. This was the only caller of
setup_mm_for_reboot(), so remove that also.
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Currently, the FDT blob needs to be in the same 512 MB region as
the kernel, so that it can be mapped into the kernel virtual memory
space very early on using a minimal set of statically allocated
translation tables.
Now that we have early fixmap support, we can relax this restriction,
by moving the permanent FDT mapping to the fixmap region instead.
This way, the FDT blob may be anywhere in memory.
This also moves the vetting of the FDT to mmu.c, since the early
init code in head.S does not handle mapping of the FDT anymore.
At the same time, fix up some comments in head.S that have gone stale.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Now that we have moved the call to SetVirtualAddressMap() to the stub,
UEFI has no use for the ID map, so we can drop the code that installs
ID mappings for UEFI memory regions.
Acked-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
For UEFI, we need to install the memory mappings used for Runtime Services
in a dedicated set of page tables. Add create_pgd_mapping(), which allows
us to allocate and install those page table entries early.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Pull ARM64 EFI update from Peter Anvin:
"By agreement with the ARM64 EFI maintainers, we have agreed to make
-tip the upstream for all EFI patches. That is why this patchset
comes from me :)
This patchset enables EFI stub support for ARM64, like we already have
on x86"
* 'arm64-efi-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
arm64: efi: only attempt efi map setup if booting via EFI
efi/arm64: ignore dtb= when UEFI SecureBoot is enabled
doc: arm64: add description of EFI stub support
arm64: efi: add EFI stub
doc: arm: add UEFI support documentation
arm64: add EFI runtime services
efi: Add shared FDT related functions for ARM/ARM64
arm64: Add function to create identity mappings
efi: add helper function to get UEFI params from FDT
doc: efi-stub.txt updates for ARM
lib: add fdt_empty_tree.c
At boot time, before switching to a virtual UEFI memory map, firmware
expects UEFI memory and IO regions to be identity mapped whenever
kernel makes runtime services calls. The existing early boot code
creates an identity map of kernel text/data but this is not sufficient
for UEFI. This patch adds a create_id_mapping() function which reuses
the core code of the existing create_mapping().
Signed-off-by: Mark Salter <msalter@redhat.com>
[ Fixed error message formatting (%pa). ]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Ard Biesheuvel