When FEAT_LPA{,2} are not implemented, the ID_AA64MMFR0_EL1.PARange and
TCR.IPS values corresponding with 52-bit physical addressing are
reserved.
Setting the TCR.IPS field to 0b110 (52-bit physical addressing) has side
effects, such as how the TTBRn_ELx.BADDR fields are interpreted, and so
it is important that disabling FEAT_LPA2 (by overriding the
ID_AA64MMFR0.TGran fields) also presents a PARange field consistent with
that.
So limit the field to 48 bits unless LPA2 is enabled, and update
existing references to use the override consistently.
Fixes: 352b0395b5 ("arm64: Enable 52-bit virtual addressing for 4k and 16k granule configs")
Cc: stable@vger.kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241212081841.2168124-10-ardb+git@google.com
Signed-off-by: Will Deacon <will@kernel.org>
* arm64/for-next/perf:
perf: Switch back to struct platform_driver::remove()
perf: arm_pmuv3: Add support for Samsung Mongoose PMU
dt-bindings: arm: pmu: Add Samsung Mongoose core compatible
perf/dwc_pcie: Fix typos in event names
perf/dwc_pcie: Add support for Ampere SoCs
ARM: pmuv3: Add missing write_pmuacr()
perf/marvell: Marvell PEM performance monitor support
perf/arm_pmuv3: Add PMUv3.9 per counter EL0 access control
perf/dwc_pcie: Convert the events with mixed case to lowercase
perf/cxlpmu: Support missing events in 3.1 spec
perf: imx_perf: add support for i.MX91 platform
dt-bindings: perf: fsl-imx-ddr: Add i.MX91 compatible
drivers perf: remove unused field pmu_node
* for-next/gcs: (42 commits)
: arm64 Guarded Control Stack user-space support
kselftest/arm64: Fix missing printf() argument in gcs/gcs-stress.c
arm64/gcs: Fix outdated ptrace documentation
kselftest/arm64: Ensure stable names for GCS stress test results
kselftest/arm64: Validate that GCS push and write permissions work
kselftest/arm64: Enable GCS for the FP stress tests
kselftest/arm64: Add a GCS stress test
kselftest/arm64: Add GCS signal tests
kselftest/arm64: Add test coverage for GCS mode locking
kselftest/arm64: Add a GCS test program built with the system libc
kselftest/arm64: Add very basic GCS test program
kselftest/arm64: Always run signals tests with GCS enabled
kselftest/arm64: Allow signals tests to specify an expected si_code
kselftest/arm64: Add framework support for GCS to signal handling tests
kselftest/arm64: Add GCS as a detected feature in the signal tests
kselftest/arm64: Verify the GCS hwcap
arm64: Add Kconfig for Guarded Control Stack (GCS)
arm64/ptrace: Expose GCS via ptrace and core files
arm64/signal: Expose GCS state in signal frames
arm64/signal: Set up and restore the GCS context for signal handlers
arm64/mm: Implement map_shadow_stack()
...
* for-next/probes:
: Various arm64 uprobes/kprobes cleanups
arm64: insn: Simulate nop instruction for better uprobe performance
arm64: probes: Remove probe_opcode_t
arm64: probes: Cleanup kprobes endianness conversions
arm64: probes: Move kprobes-specific fields
arm64: probes: Fix uprobes for big-endian kernels
arm64: probes: Fix simulate_ldr*_literal()
arm64: probes: Remove broken LDR (literal) uprobe support
* for-next/asm-offsets:
: arm64 asm-offsets.c cleanup (remove unused offsets)
arm64: asm-offsets: remove PREEMPT_DISABLE_OFFSET
arm64: asm-offsets: remove DMA_{TO,FROM}_DEVICE
arm64: asm-offsets: remove VM_EXEC and PAGE_SZ
arm64: asm-offsets: remove MM_CONTEXT_ID
arm64: asm-offsets: remove COMPAT_{RT_,SIGFRAME_REGS_OFFSET
arm64: asm-offsets: remove VMA_VM_*
arm64: asm-offsets: remove TSK_ACTIVE_MM
* for-next/tlb:
: TLB flushing optimisations
arm64: optimize flush tlb kernel range
arm64: tlbflush: add __flush_tlb_range_limit_excess()
* for-next/misc:
: Miscellaneous patches
arm64: tls: Fix context-switching of tpidrro_el0 when kpti is enabled
arm64/ptrace: Clarify documentation of VL configuration via ptrace
acpi/arm64: remove unnecessary cast
arm64/mm: Change protval as 'pteval_t' in map_range()
arm64: uprobes: Optimize cache flushes for xol slot
acpi/arm64: Adjust error handling procedure in gtdt_parse_timer_block()
arm64: fix .data.rel.ro size assertion when CONFIG_LTO_CLANG
arm64/ptdump: Test both PTE_TABLE_BIT and PTE_VALID for block mappings
arm64/mm: Sanity check PTE address before runtime P4D/PUD folding
arm64/mm: Drop setting PTE_TYPE_PAGE in pte_mkcont()
ACPI: GTDT: Tighten the check for the array of platform timer structures
arm64/fpsimd: Fix a typo
arm64: Expose ID_AA64ISAR1_EL1.XS to sanitised feature consumers
arm64: Return early when break handler is found on linked-list
arm64/mm: Re-organize arch_make_huge_pte()
arm64/mm: Drop _PROT_SECT_DEFAULT
arm64: Add command-line override for ID_AA64MMFR0_EL1.ECV
arm64: head: Drop SWAPPER_TABLE_SHIFT
arm64: cpufeature: add POE to cpucap_is_possible()
arm64/mm: Change pgattr_change_is_safe() arguments as pteval_t
* for-next/mte:
: Various MTE improvements
selftests: arm64: add hugetlb mte tests
hugetlb: arm64: add mte support
* for-next/sysreg:
: arm64 sysreg updates
arm64/sysreg: Update ID_AA64MMFR1_EL1 to DDI0601 2024-09
* for-next/stacktrace:
: arm64 stacktrace improvements
arm64: preserve pt_regs::stackframe during exec*()
arm64: stacktrace: unwind exception boundaries
arm64: stacktrace: split unwind_consume_stack()
arm64: stacktrace: report recovered PCs
arm64: stacktrace: report source of unwind data
arm64: stacktrace: move dump_backtrace() to kunwind_stack_walk()
arm64: use a common struct frame_record
arm64: pt_regs: swap 'unused' and 'pmr' fields
arm64: pt_regs: rename "pmr_save" -> "pmr"
arm64: pt_regs: remove stale big-endian layout
arm64: pt_regs: assert pt_regs is a multiple of 16 bytes
* for-next/hwcap3:
: Add AT_HWCAP3 support for arm64 (also wire up AT_HWCAP4)
arm64: Support AT_HWCAP3
binfmt_elf: Wire up AT_HWCAP3 at AT_HWCAP4
* for-next/kselftest: (30 commits)
: arm64 kselftest fixes/cleanups
kselftest/arm64: Try harder to generate different keys during PAC tests
kselftest/arm64: Don't leak pipe fds in pac.exec_sign_all()
kselftest/arm64: Corrupt P0 in the irritator when testing SSVE
kselftest/arm64: Add FPMR coverage to fp-ptrace
kselftest/arm64: Expand the set of ZA writes fp-ptrace does
kselftets/arm64: Use flag bits for features in fp-ptrace assembler code
kselftest/arm64: Enable build of PAC tests with LLVM=1
kselftest/arm64: Check that SVCR is 0 in signal handlers
kselftest/arm64: Fix printf() compiler warnings in the arm64 syscall-abi.c tests
kselftest/arm64: Fix printf() warning in the arm64 MTE prctl() test
kselftest/arm64: Fix printf() compiler warnings in the arm64 fp tests
kselftest/arm64: Fix build with stricter assemblers
kselftest/arm64: Test signal handler state modification in fp-stress
kselftest/arm64: Provide a SIGUSR1 handler in the kernel mode FP stress test
kselftest/arm64: Implement irritators for ZA and ZT
kselftest/arm64: Remove unused ADRs from irritator handlers
kselftest/arm64: Correct misleading comments on fp-stress irritators
kselftest/arm64: Poll less often while waiting for fp-stress children
kselftest/arm64: Increase frequency of signal delivery in fp-stress
kselftest/arm64: Fix encoding for SVE B16B16 test
...
* for-next/crc32:
: Optimise CRC32 using PMULL instructions
arm64/crc32: Implement 4-way interleave using PMULL
arm64/crc32: Reorganize bit/byte ordering macros
arm64/lib: Handle CRC-32 alternative in C code
* for-next/guest-cca:
: Support for running Linux as a guest in Arm CCA
arm64: Document Arm Confidential Compute
virt: arm-cca-guest: TSM_REPORT support for realms
arm64: Enable memory encrypt for Realms
arm64: mm: Avoid TLBI when marking pages as valid
arm64: Enforce bounce buffers for realm DMA
efi: arm64: Map Device with Prot Shared
arm64: rsi: Map unprotected MMIO as decrypted
arm64: rsi: Add support for checking whether an MMIO is protected
arm64: realm: Query IPA size from the RMM
arm64: Detect if in a realm and set RIPAS RAM
arm64: rsi: Add RSI definitions
* for-next/haft:
: Support for arm64 FEAT_HAFT
arm64: pgtable: Warn unexpected pmdp_test_and_clear_young()
arm64: Enable ARCH_HAS_NONLEAF_PMD_YOUNG
arm64: Add support for FEAT_HAFT
arm64: setup: name 'tcr2' register
arm64/sysreg: Update ID_AA64MMFR1_EL1 register
* for-next/scs:
: Dynamic shadow call stack fixes
arm64/scs: Drop unused prototype __pi_scs_patch_vmlinux()
arm64/scs: Deal with 64-bit relative offsets in FDE frames
arm64/scs: Fix handling of DWARF augmentation data in CIE/FDE frames
pgprot_t has been defined as an encapsulated structure with pteval_t as its
element. Hence it is prudent to use pteval_t as the type instead of via the
size based u64. Besides pteval_t type might be different size later on with
FEAT_D128.
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Link: https://lore.kernel.org/r/20241111075249.609493-1-anshuman.khandual@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In some cases, the compiler may decide to emit DWARF FDE frames with
64-bit signed fields for the code offset and range fields. This may
happen when using the large code model, for instance, which permits
an executable to be spread out over more than 4 GiB of address space.
Whether this is the case can be inferred from the augmentation data in
the CIE frame, so decode this data before processing the FDE frames.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20241106185513.3096442-7-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The dynamic SCS patching code pretends to parse the DWARF augmentation
data in the CIE (header) frame, and handle accordingly when processing
the individual FDE frames based on this CIE frame. However, the boolean
variable is defined inside the loop, and so the parsed value is ignored.
The same applies to the code alignment field, which is also read from
the header but then discarded.
This was never spotted before because Clang is the only compiler that
supports dynamic SCS patching (which is essentially an Android feature),
and the unwind tables it produces are highly uniform, and match the
de facto defaults.
So instead of testing for the 'z' flag in the augmentation data field,
require a fixed augmentation data string of 'zR', and simplify the rest
of the code accordingly.
Also introduce some error codes to specify why the patching failed, and
log it to the kernel console on failure when this happens when loading a
module. (Doing so for vmlinux is infeasible, as the patching is done
extremely early in the boot.)
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20241106185513.3096442-6-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
It appears that relatively popular hardware out there implements
the CNTPOFF_EL2 variant of FEAT_ECV, advertises it via ID_AA64MMFR0_EL1,
but cannot be bothered to set SCR_EL3.ECVEn to 1.
You would probably think that "this is fine, EL3 will take the
trap on access to CNTPOFF_EL2 and flip the ECVEn bit", as that's
what a semi-decent firmware implementation would do.
But no. None of that. This particular implementation takes the trap,
considers its purpose in life, decides that it has none, and *RESETS*
the system.
Yes, x1e001de, I'm talking about you.
In order to allow this machine to be promoted slightly above the
level of a glorified door-stop, add a new "id_aa64mmfr0.ecv" override.
allowing the kernel to pretend this option was never there.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241021181434.1052974-1-maz@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Hook up an override for GCS, allowing it to be disabled from the command
line by specifying arm64.nogcs in case there are problems.
Reviewed-by: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241001-arm64-gcs-v13-17-222b78d87eee@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
In the attempt to clear and recreate the initial ID map for LPA2, we
wrongly use 'start - end' as the map size and make the memset() almost a
nop.
Fix it by passing the correct map size.
Fixes: 9684ec186f ("arm64: Enable LPA2 at boot if supported by the system")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240621092809.162-1-yuzenghui@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
- Avoid 'constexpr', which is a keyword in C23
- Allow 'dtbs_check' and 'dt_compatible_check' run independently of
'dt_binding_check'
- Fix weak references to avoid GOT entries in position-independent
code generation
- Convert the last use of 'optional' property in arch/sh/Kconfig
- Remove support for the 'optional' property in Kconfig
- Remove support for Clang's ThinLTO caching, which does not work with
the .incbin directive
- Change the semantics of $(src) so it always points to the source
directory, which fixes Makefile inconsistencies between upstream and
downstream
- Fix 'make tar-pkg' for RISC-V to produce a consistent package
- Provide reasonable default coverage for objtool, sanitizers, and
profilers
- Remove redundant OBJECT_FILES_NON_STANDARD, KASAN_SANITIZE, etc.
- Remove the last use of tristate choice in drivers/rapidio/Kconfig
- Various cleanups and fixes in Kconfig
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Merge tag 'kbuild-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Avoid 'constexpr', which is a keyword in C23
- Allow 'dtbs_check' and 'dt_compatible_check' run independently of
'dt_binding_check'
- Fix weak references to avoid GOT entries in position-independent code
generation
- Convert the last use of 'optional' property in arch/sh/Kconfig
- Remove support for the 'optional' property in Kconfig
- Remove support for Clang's ThinLTO caching, which does not work with
the .incbin directive
- Change the semantics of $(src) so it always points to the source
directory, which fixes Makefile inconsistencies between upstream and
downstream
- Fix 'make tar-pkg' for RISC-V to produce a consistent package
- Provide reasonable default coverage for objtool, sanitizers, and
profilers
- Remove redundant OBJECT_FILES_NON_STANDARD, KASAN_SANITIZE, etc.
- Remove the last use of tristate choice in drivers/rapidio/Kconfig
- Various cleanups and fixes in Kconfig
* tag 'kbuild-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (46 commits)
kconfig: use sym_get_choice_menu() in sym_check_prop()
rapidio: remove choice for enumeration
kconfig: lxdialog: remove initialization with A_NORMAL
kconfig: m/nconf: merge two item_add_str() calls
kconfig: m/nconf: remove dead code to display value of bool choice
kconfig: m/nconf: remove dead code to display children of choice members
kconfig: gconf: show checkbox for choice correctly
kbuild: use GCOV_PROFILE and KCSAN_SANITIZE in scripts/Makefile.modfinal
Makefile: remove redundant tool coverage variables
kbuild: provide reasonable defaults for tool coverage
modules: Drop the .export_symbol section from the final modules
kconfig: use menu_list_for_each_sym() in sym_check_choice_deps()
kconfig: use sym_get_choice_menu() in conf_write_defconfig()
kconfig: add sym_get_choice_menu() helper
kconfig: turn defaults and additional prompt for choice members into error
kconfig: turn missing prompt for choice members into error
kconfig: turn conf_choice() into void function
kconfig: use linked list in sym_set_changed()
kconfig: gconf: use MENU_CHANGED instead of SYMBOL_CHANGED
kconfig: gconf: remove debug code
...
* Move a lot of state that was previously stored on a per vcpu
basis into a per-CPU area, because it is only pertinent to the
host while the vcpu is loaded. This results in better state
tracking, and a smaller vcpu structure.
* Add full handling of the ERET/ERETAA/ERETAB instructions in
nested virtualisation. The last two instructions also require
emulating part of the pointer authentication extension.
As a result, the trap handling of pointer authentication has
been greatly simplified.
* Turn the global (and not very scalable) LPI translation cache
into a per-ITS, scalable cache, making non directly injected
LPIs much cheaper to make visible to the vcpu.
* A batch of pKVM patches, mostly fixes and cleanups, as the
upstreaming process seems to be resuming. Fingers crossed!
* Allocate PPIs and SGIs outside of the vcpu structure, allowing
for smaller EL2 mapping and some flexibility in implementing
more or less than 32 private IRQs.
* Purge stale mpidr_data if a vcpu is created after the MPIDR
map has been created.
* Preserve vcpu-specific ID registers across a vcpu reset.
* Various minor cleanups and improvements.
LoongArch:
* Add ParaVirt IPI support.
* Add software breakpoint support.
* Add mmio trace events support.
RISC-V:
* Support guest breakpoints using ebreak
* Introduce per-VCPU mp_state_lock and reset_cntx_lock
* Virtualize SBI PMU snapshot and counter overflow interrupts
* New selftests for SBI PMU and Guest ebreak
* Some preparatory work for both TDX and SNP page fault handling.
This also cleans up the page fault path, so that the priorities
of various kinds of fauls (private page, no memory, write
to read-only slot, etc.) are easier to follow.
x86:
* Minimize amount of time that shadow PTEs remain in the special
REMOVED_SPTE state. This is a state where the mmu_lock is held for
reading but concurrent accesses to the PTE have to spin; shortening
its use allows other vCPUs to repopulate the zapped region while
the zapper finishes tearing down the old, defunct page tables.
* Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID field,
which is defined by hardware but left for software use. This lets KVM
communicate its inability to map GPAs that set bits 51:48 on hosts
without 5-level nested page tables. Guest firmware is expected to
use the information when mapping BARs; this avoids that they end up at
a legal, but unmappable, GPA.
* Fixed a bug where KVM would not reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
* As usual, a bunch of code cleanups.
x86 (AMD):
* Implement a new and improved API to initialize SEV and SEV-ES VMs, which
will also be extendable to SEV-SNP. The new API specifies the desired
encryption in KVM_CREATE_VM and then separately initializes the VM.
The new API also allows customizing the desired set of VMSA features;
the features affect the measurement of the VM's initial state, and
therefore enabling them cannot be done tout court by the hypervisor.
While at it, the new API includes two bugfixes that couldn't be
applied to the old one without a flag day in userspace or without
affecting the initial measurement. When a SEV-ES VM is created with
the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are
rejected once the VMSA has been encrypted. Also, the FPU and AVX
state will be synchronized and encrypted too.
* Support for GHCB version 2 as applicable to SEV-ES guests. This, once
more, is only accessible when using the new KVM_SEV_INIT2 flow for
initialization of SEV-ES VMs.
x86 (Intel):
* An initial bunch of prerequisite patches for Intel TDX were merged.
They generally don't do anything interesting. The only somewhat user
visible change is a new debugging mode that checks that KVM's MMU
never triggers a #VE virtualization exception in the guest.
* Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig VM-Exit to
L1, as per the SDM.
Generic:
* Use vfree() instead of kvfree() for allocations that always use vcalloc()
or __vcalloc().
* Remove .change_pte() MMU notifier - the changes to non-KVM code are
small and Andrew Morton asked that I also take those through the KVM
tree. The callback was only ever implemented by KVM (which was also the
original user of MMU notifiers) but it had been nonfunctional ever since
calls to set_pte_at_notify were wrapped with invalidate_range_start
and invalidate_range_end... in 2012.
Selftests:
* Enhance the demand paging test to allow for better reporting and stressing
of UFFD performance.
* Convert the steal time test to generate TAP-friendly output.
* Fix a flaky false positive in the xen_shinfo_test due to comparing elapsed
time across two different clock domains.
* Skip the MONITOR/MWAIT test if the host doesn't actually support MWAIT.
* Avoid unnecessary use of "sudo" in the NX hugepage test wrapper shell
script, to play nice with running in a minimal userspace environment.
* Allow skipping the RSEQ test's sanity check that the vCPU was able to
complete a reasonable number of KVM_RUNs, as the assert can fail on a
completely valid setup. If the test is run on a large-ish system that is
otherwise idle, and the test isn't affined to a low-ish number of CPUs, the
vCPU task can be repeatedly migrated to CPUs that are in deep sleep states,
which results in the vCPU having very little net runtime before the next
migration due to high wakeup latencies.
* Define _GNU_SOURCE for all selftests to fix a warning that was introduced by
a change to kselftest_harness.h late in the 6.9 cycle, and because forcing
every test to #define _GNU_SOURCE is painful.
* Provide a global pseudo-RNG instance for all tests, so that library code can
generate random, but determinstic numbers.
* Use the global pRNG to randomly force emulation of select writes from guest
code on x86, e.g. to help validate KVM's emulation of locked accesses.
* Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception
handlers at VM creation, instead of forcing tests to manually trigger the
related setup.
Documentation:
* Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"ARM:
- Move a lot of state that was previously stored on a per vcpu basis
into a per-CPU area, because it is only pertinent to the host while
the vcpu is loaded. This results in better state tracking, and a
smaller vcpu structure.
- Add full handling of the ERET/ERETAA/ERETAB instructions in nested
virtualisation. The last two instructions also require emulating
part of the pointer authentication extension. As a result, the trap
handling of pointer authentication has been greatly simplified.
- Turn the global (and not very scalable) LPI translation cache into
a per-ITS, scalable cache, making non directly injected LPIs much
cheaper to make visible to the vcpu.
- A batch of pKVM patches, mostly fixes and cleanups, as the
upstreaming process seems to be resuming. Fingers crossed!
- Allocate PPIs and SGIs outside of the vcpu structure, allowing for
smaller EL2 mapping and some flexibility in implementing more or
less than 32 private IRQs.
- Purge stale mpidr_data if a vcpu is created after the MPIDR map has
been created.
- Preserve vcpu-specific ID registers across a vcpu reset.
- Various minor cleanups and improvements.
LoongArch:
- Add ParaVirt IPI support
- Add software breakpoint support
- Add mmio trace events support
RISC-V:
- Support guest breakpoints using ebreak
- Introduce per-VCPU mp_state_lock and reset_cntx_lock
- Virtualize SBI PMU snapshot and counter overflow interrupts
- New selftests for SBI PMU and Guest ebreak
- Some preparatory work for both TDX and SNP page fault handling.
This also cleans up the page fault path, so that the priorities of
various kinds of fauls (private page, no memory, write to read-only
slot, etc.) are easier to follow.
x86:
- Minimize amount of time that shadow PTEs remain in the special
REMOVED_SPTE state.
This is a state where the mmu_lock is held for reading but
concurrent accesses to the PTE have to spin; shortening its use
allows other vCPUs to repopulate the zapped region while the zapper
finishes tearing down the old, defunct page tables.
- Advertise the max mappable GPA in the "guest MAXPHYADDR" CPUID
field, which is defined by hardware but left for software use.
This lets KVM communicate its inability to map GPAs that set bits
51:48 on hosts without 5-level nested page tables. Guest firmware
is expected to use the information when mapping BARs; this avoids
that they end up at a legal, but unmappable, GPA.
- Fixed a bug where KVM would not reject accesses to MSR that aren't
supposed to exist given the vCPU model and/or KVM configuration.
- As usual, a bunch of code cleanups.
x86 (AMD):
- Implement a new and improved API to initialize SEV and SEV-ES VMs,
which will also be extendable to SEV-SNP.
The new API specifies the desired encryption in KVM_CREATE_VM and
then separately initializes the VM. The new API also allows
customizing the desired set of VMSA features; the features affect
the measurement of the VM's initial state, and therefore enabling
them cannot be done tout court by the hypervisor.
While at it, the new API includes two bugfixes that couldn't be
applied to the old one without a flag day in userspace or without
affecting the initial measurement. When a SEV-ES VM is created with
the new VM type, KVM_GET_REGS/KVM_SET_REGS and friends are rejected
once the VMSA has been encrypted. Also, the FPU and AVX state will
be synchronized and encrypted too.
- Support for GHCB version 2 as applicable to SEV-ES guests.
This, once more, is only accessible when using the new
KVM_SEV_INIT2 flow for initialization of SEV-ES VMs.
x86 (Intel):
- An initial bunch of prerequisite patches for Intel TDX were merged.
They generally don't do anything interesting. The only somewhat
user visible change is a new debugging mode that checks that KVM's
MMU never triggers a #VE virtualization exception in the guest.
- Clear vmcs.EXIT_QUALIFICATION when synthesizing an EPT Misconfig
VM-Exit to L1, as per the SDM.
Generic:
- Use vfree() instead of kvfree() for allocations that always use
vcalloc() or __vcalloc().
- Remove .change_pte() MMU notifier - the changes to non-KVM code are
small and Andrew Morton asked that I also take those through the
KVM tree.
The callback was only ever implemented by KVM (which was also the
original user of MMU notifiers) but it had been nonfunctional ever
since calls to set_pte_at_notify were wrapped with
invalidate_range_start and invalidate_range_end... in 2012.
Selftests:
- Enhance the demand paging test to allow for better reporting and
stressing of UFFD performance.
- Convert the steal time test to generate TAP-friendly output.
- Fix a flaky false positive in the xen_shinfo_test due to comparing
elapsed time across two different clock domains.
- Skip the MONITOR/MWAIT test if the host doesn't actually support
MWAIT.
- Avoid unnecessary use of "sudo" in the NX hugepage test wrapper
shell script, to play nice with running in a minimal userspace
environment.
- Allow skipping the RSEQ test's sanity check that the vCPU was able
to complete a reasonable number of KVM_RUNs, as the assert can fail
on a completely valid setup.
If the test is run on a large-ish system that is otherwise idle,
and the test isn't affined to a low-ish number of CPUs, the vCPU
task can be repeatedly migrated to CPUs that are in deep sleep
states, which results in the vCPU having very little net runtime
before the next migration due to high wakeup latencies.
- Define _GNU_SOURCE for all selftests to fix a warning that was
introduced by a change to kselftest_harness.h late in the 6.9
cycle, and because forcing every test to #define _GNU_SOURCE is
painful.
- Provide a global pseudo-RNG instance for all tests, so that library
code can generate random, but determinstic numbers.
- Use the global pRNG to randomly force emulation of select writes
from guest code on x86, e.g. to help validate KVM's emulation of
locked accesses.
- Allocate and initialize x86's GDT, IDT, TSS, segments, and default
exception handlers at VM creation, instead of forcing tests to
manually trigger the related setup.
Documentation:
- Fix a goof in the KVM_CREATE_GUEST_MEMFD documentation"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (225 commits)
selftests/kvm: remove dead file
KVM: selftests: arm64: Test vCPU-scoped feature ID registers
KVM: selftests: arm64: Test that feature ID regs survive a reset
KVM: selftests: arm64: Store expected register value in set_id_regs
KVM: selftests: arm64: Rename helper in set_id_regs to imply VM scope
KVM: arm64: Only reset vCPU-scoped feature ID regs once
KVM: arm64: Reset VM feature ID regs from kvm_reset_sys_regs()
KVM: arm64: Rename is_id_reg() to imply VM scope
KVM: arm64: Destroy mpidr_data for 'late' vCPU creation
KVM: arm64: Use hVHE in pKVM by default on CPUs with VHE support
KVM: arm64: Fix hvhe/nvhe early alias parsing
KVM: SEV: Allow per-guest configuration of GHCB protocol version
KVM: SEV: Add GHCB handling for termination requests
KVM: SEV: Add GHCB handling for Hypervisor Feature Support requests
KVM: SEV: Add support to handle AP reset MSR protocol
KVM: x86: Explicitly zero kvm_caps during vendor module load
KVM: x86: Fully re-initialize supported_mce_cap on vendor module load
KVM: x86: Fully re-initialize supported_vm_types on vendor module load
KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create noslot pfns
KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values
...
Now Kbuild provides reasonable defaults for objtool, sanitizers, and
profilers.
Remove redundant variables.
Note:
This commit changes the coverage for some objects:
- include arch/mips/vdso/vdso-image.o into UBSAN, GCOV, KCOV
- include arch/sparc/vdso/vdso-image-*.o into UBSAN
- include arch/sparc/vdso/vma.o into UBSAN
- include arch/x86/entry/vdso/extable.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso-image-*.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vdso32-setup.o into KASAN, KCSAN, UBSAN, GCOV, KCOV
- include arch/x86/entry/vdso/vma.o into GCOV, KCOV
- include arch/x86/um/vdso/vma.o into KASAN, GCOV, KCOV
I believe these are positive effects because all of them are kernel
space objects.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
The early command line parsing treats "kvm-arm.mode=protected" as an
alias for "id_aa64mmfr1.vh=0", forcing the use of nVHE so that the host
kernel runs at EL1 with the pKVM hypervisor at EL2.
With the introduction of hVHE support in ad744e8cb3 ("arm64: Allow
arm64_sw.hvhe on command line"), the hypervisor can run using the EL2+0
translation regime. This is interesting for unusual CPUs that have VH
stuck to 1, but also because it opens the possibility of a hypervisor
"userspace" in the distant future which could be used to isolate vCPU
contexts in the hypervisor (see Marc's talk from KVM Forum 2022 [1]).
Repaint the "kvm-arm.mode=protected" alias to map to "arm64_sw.hvhe=1",
which will use hVHE on CPUs that support it and remain with nVHE
otherwise.
[1] https://www.youtube.com/watch?v=1F_Mf2j9eIo
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240501163400.15838-3-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Booting a kernel with "arm64_sw.hvhe=1 kvm-arm.mode=nvhe" on the
command-line results in KVM initialising using hVHE, whereas one might
expect the latter option to override the former.
Fix this by adding "arm64_sw.hvhe=0" to the alias expansion for
"kvm-arm.mode=nvhe".
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240501163400.15838-2-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Introducing the field 'el0' to the idreg-override for register
ID_AA64PFR0_EL1. This field is also aliased to the new kernel
command line option 'arm64.no32bit_el0' as a more recognizable
and mnemonic name to disable the execution of 32 bit userspace
applications (i.e. avoid Aarch32 execution state in EL0) from
kernel command line.
Link: https://lore.kernel.org/all/20240207105847.7739-1-andrea.porta@suse.com/
Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
Link: https://lore.kernel.org/r/20240429102833.6426-1-andrea.porta@suse.com
Signed-off-by: Will Deacon <will@kernel.org>
This reverts commit 50e3ed0f93.
The SCTLR_EL1.WXN control forces execute-never when a page has write
permissions. While the idea of hardening such write/exec combinations is
good, with permissions indirection enabled (FEAT_PIE) this control
becomes RES0. FEAT_PIE introduces a slightly different form of WXN which
only has an effect when the base permission is RWX and the write is
toggled by the permission overlay (FEAT_POE, not yet supported by the
arm64 kernel). Revert the patch for now.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/ZfGESD3a91lxH367@arm.com
Add the generated executable for relacheck to the list of ignored files.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20240222210441.33142-1-brgl@bgdev.pl
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The AArch64 virtual memory system supports a global WXN control, which
can be enabled to make all writable mappings implicitly no-exec. This is
a useful hardening feature, as it prevents mistakes in managing page
table permissions from being exploited to attack the system.
When enabled at EL1, the restrictions apply to both EL1 and EL0. EL1 is
completely under our control, and has been cleaned up to allow WXN to be
enabled from boot onwards. EL0 is not under our control, but given that
widely deployed security features such as selinux or PaX already limit
the ability of user space to create mappings that are writable and
executable at the same time, the impact of enabling this for EL0 is
expected to be limited. (For this reason, common user space libraries
that have a legitimate need for manipulating executable code already
carry fallbacks such as [0].)
If enabled at compile time, the feature can still be disabled at boot if
needed, by passing arm64.nowxn on the kernel command line.
[0] https://github.com/libffi/libffi/blob/master/src/closures.c#L440
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-88-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Update the early kernel mapping code to take 52-bit virtual addressing
into account based on the LPA2 feature. This is a bit more involved than
LVA (which is supported with 64k pages only), given that some page table
descriptor bits change meaning in this case.
To keep the handling in asm to a minimum, the initial ID map is still
created with 48-bit virtual addressing, which implies that the kernel
image must be loaded into 48-bit addressable physical memory. This is
currently required by the boot protocol, even though we happen to
support placement outside of that for LVA/64k based configurations.
Enabling LPA2 involves more than setting TCR.T1SZ to a lower value,
there is also a DS bit in TCR that needs to be set, and which changes
the meaning of bits [9:8] in all page table descriptors. Since we cannot
enable DS and every live page table descriptor at the same time, let's
pivot through another temporary mapping. This avoids the need to
reintroduce manipulations of the page tables with the MMU and caches
disabled.
To permit the LPA2 feature to be overridden on the kernel command line,
which may be necessary to work around silicon errata, or to deal with
mismatched features on heterogeneous SoC designs, test for CPU feature
overrides first, and only then enable LPA2.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-78-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add support for overriding the VARange field of the MMFR2 CPU ID
register. This permits the associated LVA feature to be overridden early
enough for the boot code that creates the kernel mapping to take it into
account.
Given that LPA2 implies LVA, disabling the latter should disable the
former as well. So override the ID_AA64MMFR0.TGran field of the current
page size as well if it advertises support for 52-bit addressing.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-71-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently, we detect CPU support for 52-bit virtual addressing (LVA)
extremely early, before creating the kernel page tables or enabling the
MMU. We cannot override the feature this early, and so large virtual
addressing is always enabled on CPUs that implement support for it if
the software support for it was enabled at build time. It also means we
rely on non-trivial code in asm to deal with this feature.
Given that both the ID map and the TTBR1 mapping of the kernel image are
guaranteed to be 48-bit addressable, it is not actually necessary to
enable support this early, and instead, we can model it as a CPU
feature. That way, we can rely on code patching to get the correct
TCR.T1SZ values programmed on secondary boot and resume from suspend.
On the primary boot path, we simply enable the MMU with 48-bit virtual
addressing initially, and update TCR.T1SZ if LVA is supported from C
code, right before creating the kernel mapping. Given that TTBR1 still
points to reserved_pg_dir at this point, updating TCR.T1SZ should be
safe without the need for explicit TLB maintenance.
Since this gets rid of all accesses to the vabits_actual variable from
asm code that occurred before TCR.T1SZ had been programmed, we no longer
have a need for this variable, and we can replace it with a C expression
that produces the correct value directly, based on the value of TCR.T1SZ.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-70-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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>
The asm code that creates the initial ID map is rather intricate and
hard to follow. This is problematic because it makes adding support for
things like LPA2 or WXN more difficult than necessary. Also, it is
parameterized like the rest of the MM code to run with a configurable
number of levels, which is rather pointless, given that all AArch64 CPUs
implement support for 48-bit virtual addressing, and that many systems
exist with DRAM located outside of the 39-bit addressable range, which
is the only smaller VA size that is widely used, and we need additional
tricks to make things work in that combination.
So let's bite the bullet, and rip out all the asm macros, and fiddly
code, and replace it with a C implementation based on the newly added
routines for creating the early kernel VA mappings. And while at it,
create the initial ID map based on 48-bit virtual addressing as well,
regardless of the number of configured levels for the kernel proper.
Note that this code may execute with the MMU and caches disabled, and is
therefore not permitted to make unaligned accesses. This shouldn't
generally happen in any case for the algorithm as implemented, but to be
sure, let's pass -mstrict-align to the compiler just in case.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-66-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The asm version of the kernel mapping code works fine for creating a
coarse grained identity map, but for mapping the kernel down to its
exact boundaries with the right attributes, it is not suitable. This is
why we create a preliminary RWX kernel mapping first, and then rebuild
it from scratch later on.
So let's reimplement this in C, in a way that will make it unnecessary
to create the kernel page tables yet another time in paging_init().
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-63-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Now that we can set BSS variables from the early code running from the
ID map, we can set memstart_offset_seed directly from the C code that
derives the value instead of passing it back and forth between C and asm
code.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-60-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Add rodata=off to the set of kernel command line options that is parsed
early using the CPU feature override detection code, so we can easily
refer to it when creating the kernel mapping.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-57-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The early kaslr code open codes the detection of 'nokaslr' on the kernel
command line, and this is no longer necessary now that the feature
detection code, which also looks for the same string, executes before
this code.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-56-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Once we update the early kernel mapping code to only map the kernel once
with the right permissions, we can no longer perform code patching via
this mapping.
So move this code to an earlier stage of the boot, right after applying
the relocations.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-54-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
We will want to parse the ID register overrides even earlier, so that we
can take them into account before creating the kernel mapping. So
migrate the code and make it work in the context of the early C runtime.
We will move the invocation to an earlier stage in a subsequent patch.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-49-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Now that we have a mini C runtime before the kernel mapping is up, we
can move the non-trivial relocation processing code out of head.S and
reimplement it in C.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-48-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
We will add some code under pi/ that contains global variables that
should not end up in __initdata, as they will not be writable via the
initial ID map. So only rely on objcopy for making the libfdt code
__init, and use explicit annotations for the rest.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-47-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The mini C runtime runs before relocations are processed, and so it
cannot rely on statically initialized pointer variables.
Add a check to ensure that such code does not get introduced by
accident, by going over the relocations in each object, identifying the
ones that operate on data sections that are part of the executable
image, and raising an error if any relocations of type R_AARCH64_ABS64
exist. Note that such relocations are permitted in other places (e.g.,
debug sections) and will never occur in compiler generated code sections
when using the small code model, so only check sections that have
SHF_ALLOC set and SHF_EXECINSTR cleared.
To accommodate cases where statically initialized symbol references are
unavoidable, introduce a special case for ELF input data sections that
have ".rodata.prel64" in their names, and in these cases, instead of
rejecting any encountered ABS64 relocations, convert them into PREL64
relocations, which don't require any runtime fixups. Note that the code
in question must still be modified to deal with this, as it needs to
convert the 64-bit signed offsets into absolute addresses before use.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-46-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Currently, we base the KASLR randomization range on a rough estimate of
the available space in the upper VA region: the lower 1/4th has the
module region and the upper 1/4th has the fixmap, vmemmap and PCI I/O
ranges, and so we pick a random location in the remaining space in the
middle.
Once we enable support for 5-level paging with 4k pages, this no longer
works: the vmemmap region, being dimensioned to cover a 52-bit linear
region, takes up so much space in the upper VA region (the size of which
is based on a 48-bit VA space for compatibility with non-LVA hardware)
that the region above the vmalloc region takes up more than a quarter of
the available space.
So instead of a heuristic, let's derive the randomization range from the
actual boundaries of the vmalloc region.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231213084024.2367360-16-ardb@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
In subsequent patches, mark portions of the early C code will be marked
as __init. Unfortunarely, __init implies __latent_entropy, and this
would result in the early C code being instrumented in an unsafe manner.
Disable the latent entropy plugin for the early C code.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20231129111555.3594833-44-ardb@google.com
Signed-off-by: Will Deacon <will@kernel.org>
Enable asynchronous unwind table generation for both the core kernel as
well as modules, and emit the resulting .eh_frame sections as init code
so we can use the unwind directives for code patching at boot or module
load time.
This will be used by dynamic shadow call stack support, which will rely
on code patching rather than compiler codegen to emit the shadow call
stack push and pop instructions.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20221027155908.1940624-2-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Commit aacd149b62 ("arm64: head: avoid relocating the kernel twice for
KASLR") adds the new file arch/arm64/kernel/pi/kaslr_early.c with a small
code part guarded by '#ifdef CONFIG_ARCH_RANDOM'.
Concurrently, commit 9592eef7c1 ("random: remove CONFIG_ARCH_RANDOM")
removes the config CONFIG_ARCH_RANDOM and turns all '#ifdef
CONFIG_ARCH_RANDOM' code parts into unconditional code parts, which is
generally safe to do.
Remove a needless ifdef guard after the ARCH_RANDOM removal.
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220721100433.18286-1-lukas.bulwahn@gmail.com
Signed-off-by: Will Deacon <will@kernel.org>
Currently, when KASLR is in effect, we set up the kernel virtual address
space twice: the first time, the KASLR seed is looked up in the device
tree, and the kernel virtual mapping is torn down and recreated again,
after which the relocations are applied a second time. The latter step
means that statically initialized global pointer variables will be reset
to their initial values, and to ensure that BSS variables are not set to
values based on the initial translation, they are cleared again as well.
All of this is needed because we need the command line (taken from the
DT) to tell us whether or not to randomize the virtual address space
before entering the kernel proper. However, this code has expanded
little by little and now creates global state unrelated to the virtual
randomization of the kernel before the mapping is torn down and set up
again, and the BSS cleared for a second time. This has created some
issues in the past, and it would be better to avoid this little dance if
possible.
So instead, let's use the temporary mapping of the device tree, and
execute the bare minimum of code to decide whether or not KASLR should
be enabled, and what the seed is. Only then, create the virtual kernel
mapping, clear BSS, etc and proceed as normal. This avoids the issues
around inconsistent global state due to BSS being cleared twice, and is
generally more maintainable, as it permits us to defer all the remaining
DT parsing and KASLR initialization to a later time.
This means the relocation fixup code runs only a single time as well,
allowing us to simplify the RELR handling code too, which is not
idempotent and was therefore required to keep track of the offset that
was applied the first time around.
Note that this means we have to clone a pair of FDT library objects, so
that we can control how they are built - we need the stack protector
and other instrumentation disabled so that the code can tolerate being
called this early. Note that only the kernel page tables and the
temporary stack are mapped read-write at this point, which ensures that
the early code does not modify any global state inadvertently.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-21-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Ard Biesheuvel
Catalin Marinas
Anshuman Khandual
Marc Zyngier
Mark Brown
Zenghui Yu
Linus Torvalds
Masahiro Yamada
Will Deacon
Andrea della Porta
Bartosz Golaszewski
Lukas Bulwahn