296 Commits
Author SHA1 Message Date
Catalin Marinas 480a9e57cc Merge branches 'for-next/misc', 'for-next/tlbflush', 'for-next/ttbr-macros-cleanup', 'for-next/kselftest', 'for-next/feat_lsui', 'for-next/mpam', 'for-next/hotplug-batched-tlbi', 'for-next/bbml2-fixes', 'for-next/sysreg', 'for-next/generic-entry' and 'for-next/acpi', remote-tracking branches 'arm64/for-next/perf' and 'arm64/for-next/read-once' into for-next/core
* arm64/for-next/perf:
  : Perf updates
  perf/arm-cmn: Fix resource_size_t printk specifier in arm_cmn_init_dtc()
  perf/arm-cmn: Fix incorrect error check for devm_ioremap()
  perf: add NVIDIA Tegra410 C2C PMU
  perf: add NVIDIA Tegra410 CPU Memory Latency PMU
  perf/arm_cspmu: nvidia: Add Tegra410 PCIE-TGT PMU
  perf/arm_cspmu: nvidia: Add Tegra410 PCIE PMU
  perf/arm_cspmu: Add arm_cspmu_acpi_dev_get
  perf/arm_cspmu: nvidia: Add Tegra410 UCF PMU
  perf/arm_cspmu: nvidia: Rename doc to Tegra241
  perf/arm-cmn: Stop claiming entire iomem region
  arm64: cpufeature: Use pmuv3_implemented() function
  arm64: cpufeature: Make PMUVer and PerfMon unsigned
  KVM: arm64: Read PMUVer as unsigned

* arm64/for-next/read-once:
  : Fixes for __READ_ONCE() with CONFIG_LTO=y
  arm64, compiler-context-analysis: Permit alias analysis through __READ_ONCE() with CONFIG_LTO=y
  arm64: Optimize __READ_ONCE() with CONFIG_LTO=y

* for-next/misc:
  : Miscellaneous cleanups/fixes
  arm64: rsi: use linear-map alias for realm config buffer
  arm64: Kconfig: fix duplicate word in CMDLINE help text
  arm64: mte: Skip TFSR_EL1 checks and barriers in synchronous tag check mode
  arm64/hwcap: Generate the KERNEL_HWCAP_ definitions for the hwcaps
  arm64: kexec: Remove duplicate allocation for trans_pgd
  arm64: mm: Use generic enum pgtable_level
  arm64: scs: Remove redundant save/restore of SCS SP on entry to/from EL0
  arm64: remove ARCH_INLINE_*

* for-next/tlbflush:
  : Refactor the arm64 TLB invalidation API and implementation
  arm64: mm: __ptep_set_access_flags must hint correct TTL
  arm64: mm: Provide level hint for flush_tlb_page()
  arm64: mm: Wrap flush_tlb_page() around __do_flush_tlb_range()
  arm64: mm: More flags for __flush_tlb_range()
  arm64: mm: Refactor __flush_tlb_range() to take flags
  arm64: mm: Refactor flush_tlb_page() to use __tlbi_level_asid()
  arm64: mm: Simplify __flush_tlb_range_limit_excess()
  arm64: mm: Simplify __TLBI_RANGE_NUM() macro
  arm64: mm: Re-implement the __flush_tlb_range_op macro in C
  arm64: mm: Inline __TLBI_VADDR_RANGE() into __tlbi_range()
  arm64: mm: Push __TLBI_VADDR() into __tlbi_level()
  arm64: mm: Implicitly invalidate user ASID based on TLBI operation
  arm64: mm: Introduce a C wrapper for by-range TLB invalidation
  arm64: mm: Re-implement the __tlbi_level macro as a C function

* for-next/ttbr-macros-cleanup:
  : Cleanups of the TTBR1_* macros
  arm64/mm: Directly use TTBRx_EL1_CnP
  arm64/mm: Directly use TTBRx_EL1_ASID_MASK
  arm64/mm: Describe TTBR1_BADDR_4852_OFFSET

* for-next/kselftest:
  : arm64 kselftest updates
  selftests/arm64: Implement cmpbr_sigill() to hwcap test

* for-next/feat_lsui:
  : Futex support using FEAT_LSUI instructions to avoid toggling PAN
  arm64: armv8_deprecated: Disable swp emulation when FEAT_LSUI present
  arm64: Kconfig: Add support for LSUI
  KVM: arm64: Use CAST instruction for swapping guest descriptor
  arm64: futex: Support futex with FEAT_LSUI
  arm64: futex: Refactor futex atomic operation
  KVM: arm64: kselftest: set_id_regs: Add test for FEAT_LSUI
  KVM: arm64: Expose FEAT_LSUI to guests
  arm64: cpufeature: Add FEAT_LSUI

* for-next/mpam: (40 commits)
  : Expose MPAM to user-space via resctrl:
  :  - Add architecture context-switch and hiding of the feature from KVM.
  :  - Add interface to allow MPAM to be exposed to user-space using resctrl.
  :  - Add errata workaoround for some existing platforms.
  :  - Add documentation for using MPAM and what shape of platforms can use resctrl
  arm64: mpam: Add initial MPAM documentation
  arm_mpam: Quirk CMN-650's CSU NRDY behaviour
  arm_mpam: Add workaround for T241-MPAM-6
  arm_mpam: Add workaround for T241-MPAM-4
  arm_mpam: Add workaround for T241-MPAM-1
  arm_mpam: Add quirk framework
  arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl
  arm64: mpam: Select ARCH_HAS_CPU_RESCTRL
  arm_mpam: resctrl: Add empty definitions for assorted resctrl functions
  arm_mpam: resctrl: Update the rmid reallocation limit
  arm_mpam: resctrl: Add resctrl_arch_rmid_read()
  arm_mpam: resctrl: Allow resctrl to allocate monitors
  arm_mpam: resctrl: Add support for csu counters
  arm_mpam: resctrl: Add monitor initialisation and domain boilerplate
  arm_mpam: resctrl: Add kunit test for control format conversions
  arm_mpam: resctrl: Add support for 'MB' resource
  arm_mpam: resctrl: Wait for cacheinfo to be ready
  arm_mpam: resctrl: Add rmid index helpers
  arm_mpam: resctrl: Convert to/from MPAMs fixed-point formats
  arm_mpam: resctrl: Hide CDP emulation behind CONFIG_EXPERT
  ...

* for-next/hotplug-batched-tlbi:
  : arm64/mm: Enable batched TLB flush in unmap_hotplug_range()
  arm64/mm: Reject memory removal that splits a kernel leaf mapping
  arm64/mm: Enable batched TLB flush in unmap_hotplug_range()

* for-next/bbml2-fixes:
  : Fixes for realm guest and BBML2_NOABORT
  arm64: mm: Remove pmd_sect() and pud_sect()
  arm64: mm: Handle invalid large leaf mappings correctly
  arm64: mm: Fix rodata=full block mapping support for realm guests

* for-next/sysreg:
  : arm64 sysreg updates
  arm64/sysreg: Update ID_AA64SMFR0_EL1 description to DDI0601 2025-12
  arm64/sysreg: Update ID_AA64ZFR0_EL1 description to DDI0601 2025-12
  arm64/sysreg: Update ID_AA64FPFR0_EL1 description to DDI0601 2025-12
  arm64/sysreg: Update ID_AA64ISAR2_EL1 description to DDI0601 2025-12
  arm64/sysreg: Update ID_AA64ISAR0_EL1 description to DDI0601 2025-12
  arm64/sysreg: Update SMIDR_EL1 to DDI0601 2025-06

* for-next/generic-entry:
  : More arm64 refactoring towards using the generic entry code
  arm64: Check DAIF (and PMR) at task-switch time
  arm64: entry: Use split preemption logic
  arm64: entry: Use irqentry_{enter_from,exit_to}_kernel_mode()
  arm64: entry: Consistently prefix arm64-specific wrappers
  arm64: entry: Don't preempt with SError or Debug masked
  entry: Split preemption from irqentry_exit_to_kernel_mode()
  entry: Split kernel mode logic from irqentry_{enter,exit}()
  entry: Move irqentry_enter() prototype later
  entry: Remove local_irq_{enable,disable}_exit_to_user()
  entry: Fix stale comment for irqentry_enter()

* for-next/acpi:
  : arm64 ACPI updates
  ACPI: AGDI: fix missing newline in error message
2026-04-10 14:22:24 +01:00
Anshuman KhandualandCatalin Marinas d989010bbe arm64/mm: Directly use TTBRx_EL1_ASID_MASK
Replace all TTBR_ASID_MASK macro instances with TTBRx_EL1_ASID_MASK which
is a standard field mask from tools sysreg format. Drop the now redundant
custom macro TTBR_ASID_MASK. No functional change.

Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: kvmarm@lists.linux.dev
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2026-03-14 16:12:27 +00:00
Will DeaconandCatalin Marinas 3ce8f5860f arm64: scs: Remove redundant save/restore of SCS SP on entry to/from EL0
When returning to userspace, the SCS is empty and so the SCS SP just
points to the base address of the SCS page.

Rather than saving and restoring this address in the current task, we
can simply restore the SCS SP to point at the base of the stack on entry
to EL1 from EL0.

Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2026-03-13 17:17:58 +00:00
Linus Torvalds 6fb44438a5 Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Catalin Marinas:
 "A quick summary: perf support for Branch Record Buffer Extensions
  (BRBE), typical PMU hardware updates, small additions to MTE for
  store-only tag checking and exposing non-address bits to signal
  handlers, HAVE_LIVEPATCH enabled on arm64, VMAP_STACK forced on.

  There is also a TLBI optimisation on hardware that does not require
  break-before-make when changing the user PTEs between contiguous and
  non-contiguous.

  More details:

  Perf and PMU updates:

   - Add support for new (v3) Hisilicon SLLC and DDRC PMUs

   - Add support for Arm-NI PMU integrations that share interrupts
     between clock domains within a given instance

   - Allow SPE to be configured with a lower sample period than the
     minimum recommendation advertised by PMSIDR_EL1.Interval

   - Add suppport for Arm's "Branch Record Buffer Extension" (BRBE)

   - Adjust the perf watchdog period according to cpu frequency changes

   - Minor driver fixes and cleanups

  Hardware features:

   - Support for MTE store-only checking (FEAT_MTE_STORE_ONLY)

   - Support for reporting the non-address bits during a synchronous MTE
     tag check fault (FEAT_MTE_TAGGED_FAR)

   - Optimise the TLBI when folding/unfolding contiguous PTEs on
     hardware with FEAT_BBM (break-before-make) level 2 and no TLB
     conflict aborts

  Software features:

   - Enable HAVE_LIVEPATCH after implementing arch_stack_walk_reliable()
     and using the text-poke API for late module relocations

   - Force VMAP_STACK always on and change arm64_efi_rt_init() to use
     arch_alloc_vmap_stack() in order to avoid KASAN false positives

  ACPI:

   - Improve SPCR handling and messaging on systems lacking an SPCR
     table

  Debug:

   - Simplify the debug exception entry path

   - Drop redundant DBG_MDSCR_* macros

  Kselftests:

   - Cleanups and improvements for SME, SVE and FPSIMD tests

  Miscellaneous:

   - Optimise loop to reduce redundant operations in contpte_ptep_get()

   - Remove ISB when resetting POR_EL0 during signal handling

   - Mark the kernel as tainted on SEA and SError panic

   - Remove redundant gcs_free() call"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (93 commits)
  arm64/gcs: task_gcs_el0_enable() should use passed task
  arm64: Kconfig: Keep selects somewhat alphabetically ordered
  arm64: signal: Remove ISB when resetting POR_EL0
  kselftest/arm64: Handle attempts to disable SM on SME only systems
  kselftest/arm64: Fix SVE write data generation for SME only systems
  kselftest/arm64: Test SME on SME only systems in fp-ptrace
  kselftest/arm64: Test FPSIMD format data writes via NT_ARM_SVE in fp-ptrace
  kselftest/arm64: Allow sve-ptrace to run on SME only systems
  arm64/mm: Drop redundant addr increment in set_huge_pte_at()
  kselftest/arm4: Provide local defines for AT_HWCAP3
  arm64: Mark kernel as tainted on SAE and SError panic
  arm64/gcs: Don't call gcs_free() when releasing task_struct
  drivers/perf: hisi: Support PMUs with no interrupt
  drivers/perf: hisi: Relax the event number check of v2 PMUs
  drivers/perf: hisi: Add support for HiSilicon SLLC v3 PMU driver
  drivers/perf: hisi: Use ACPI driver_data to retrieve SLLC PMU information
  drivers/perf: hisi: Add support for HiSilicon DDRC v3 PMU driver
  drivers/perf: hisi: Simplify the probe process for each DDRC version
  perf/arm-ni: Support sharing IRQs within an NI instance
  perf/arm-ni: Consolidate CPU affinity handling
  ...
2025-07-29 20:21:54 -07:00
Linus Torvalds 8e736a2eea Merge tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull hardening updates from Kees Cook:

 - Introduce and start using TRAILING_OVERLAP() helper for fixing
   embedded flex array instances (Gustavo A. R. Silva)

 - mux: Convert mux_control_ops to a flex array member in mux_chip
   (Thorsten Blum)

 - string: Group str_has_prefix() and strstarts() (Andy Shevchenko)

 - Remove KCOV instrumentation from __init and __head (Ritesh Harjani,
   Kees Cook)

 - Refactor and rename stackleak feature to support Clang

 - Add KUnit test for seq_buf API

 - Fix KUnit fortify test under LTO

* tag 'hardening-v6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (22 commits)
  sched/task_stack: Add missing const qualifier to end_of_stack()
  kstack_erase: Support Clang stack depth tracking
  kstack_erase: Add -mgeneral-regs-only to silence Clang warnings
  init.h: Disable sanitizer coverage for __init and __head
  kstack_erase: Disable kstack_erase for all of arm compressed boot code
  x86: Handle KCOV __init vs inline mismatches
  arm64: Handle KCOV __init vs inline mismatches
  s390: Handle KCOV __init vs inline mismatches
  arm: Handle KCOV __init vs inline mismatches
  mips: Handle KCOV __init vs inline mismatch
  powerpc/mm/book3s64: Move kfence and debug_pagealloc related calls to __init section
  configs/hardening: Enable CONFIG_INIT_ON_FREE_DEFAULT_ON
  configs/hardening: Enable CONFIG_KSTACK_ERASE
  stackleak: Split KSTACK_ERASE_CFLAGS from GCC_PLUGINS_CFLAGS
  stackleak: Rename stackleak_track_stack to __sanitizer_cov_stack_depth
  stackleak: Rename STACKLEAK to KSTACK_ERASE
  seq_buf: Introduce KUnit tests
  string: Group str_has_prefix() and strstarts()
  kunit/fortify: Add back "volatile" for sizeof() constants
  acpi: nfit: intel: avoid multiple -Wflex-array-member-not-at-end warnings
  ...
2025-07-28 17:16:12 -07:00
Ada Couprie DiazandWill Deacon d42e6c20de arm64/entry: Mask DAIF in cpu_switch_to(), call_on_irq_stack()
`cpu_switch_to()` and `call_on_irq_stack()` manipulate SP to change
to different stacks along with the Shadow Call Stack if it is enabled.
Those two stack changes cannot be done atomically and both functions
can be interrupted by SErrors or Debug Exceptions which, though unlikely,
is very much broken : if interrupted, we can end up with mismatched stacks
and Shadow Call Stack leading to clobbered stacks.

In `cpu_switch_to()`, it can happen when SP_EL0 points to the new task,
but x18 stills points to the old task's SCS. When the interrupt handler
tries to save the task's SCS pointer, it will save the old task
SCS pointer (x18) into the new task struct (pointed to by SP_EL0),
clobbering it.

In `call_on_irq_stack()`, it can happen when switching from the task stack
to the IRQ stack and when switching back. In both cases, we can be
interrupted when the SCS pointer points to the IRQ SCS, but SP points to
the task stack. The nested interrupt handler pushes its return addresses
on the IRQ SCS. It then detects that SP points to the task stack,
calls `call_on_irq_stack()` and clobbers the task SCS pointer with
the IRQ SCS pointer, which it will also use !

This leads to tasks returning to addresses on the wrong SCS,
or even on the IRQ SCS, triggering kernel panics via CONFIG_VMAP_STACK
or FPAC if enabled.

This is possible on a default config, but unlikely.
However, when enabling CONFIG_ARM64_PSEUDO_NMI, DAIF is unmasked and
instead the GIC is responsible for filtering what interrupts the CPU
should receive based on priority.
Given the goal of emulating NMIs, pseudo-NMIs can be received by the CPU
even in `cpu_switch_to()` and `call_on_irq_stack()`, possibly *very*
frequently depending on the system configuration and workload, leading
to unpredictable kernel panics.

Completely mask DAIF in `cpu_switch_to()` and restore it when returning.
Do the same in `call_on_irq_stack()`, but restore and mask around
the branch.
Mask DAIF even if CONFIG_SHADOW_CALL_STACK is not enabled for consistency
of behaviour between all configurations.

Introduce and use an assembly macro for saving and masking DAIF,
as the existing one saves but only masks IF.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Reported-by: Cristian Prundeanu <cpru@amazon.com>
Fixes: 59b37fe52f ("arm64: Stash shadow stack pointer in the task struct on interrupt")
Tested-by: Cristian Prundeanu <cpru@amazon.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20250718142814.133329-1-ada.coupriediaz@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2025-07-22 16:39:30 +01:00
Kees Cook 57fbad15c2 stackleak: Rename STACKLEAK to KSTACK_ERASE
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-21 21:35:01 -07:00
Breno LeitaoandWill Deacon 9d1869f0f5 arm64: remove CONFIG_VMAP_STACK checks from entry code
With VMAP_STACK now always enabled on arm64, remove all CONFIG_VMAP_STACK
conditionals from entry handling in arch/arm64/kernel/entry-common.c and
arch/arm64/kernel/entry.S.

This change unconditionally includes the bad stack handling and overflow
detection logic, simplifying the code and reflecting the mandatory use of
VMAP_STACK for all arm64 kernel builds.

Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20250707-arm64_vmap-v1-8-8de98ca0f91c@debian.org
Signed-off-by: Will Deacon <will@kernel.org>
2025-07-08 13:41:09 +01:00
Mark RutlandandCatalin Marinas c2c6b27b5a arm64: stacktrace: unwind exception boundaries
When arm64's stack unwinder encounters an exception boundary, it uses
the pt_regs::stackframe created by the entry code, which has a copy of
the PC and FP at the time the exception was taken. The unwinder doesn't
know anything about pt_regs, and reports the PC from the stackframe, but
does not report the LR.

The LR is only guaranteed to contain the return address at function call
boundaries, and can be used as a scratch register at other times, so the
LR at an exception boundary may or may not be a legitimate return
address. It would be useful to report the LR value regardless, as it can
be helpful when debugging, and in future it will be helpful for reliable
stacktrace support.

This patch changes the way we unwind across exception boundaries,
allowing both the PC and LR to be reported. The entry code creates a
frame_record_meta structure embedded within pt_regs, which the unwinder
uses to find the pt_regs. The unwinder can then extract pt_regs::pc and
pt_regs::lr as two separate unwind steps before continuing with a
regular walk of frame records.

When a PC is unwound from pt_regs::lr, dump_backtrace() will log this
with an "L" marker so that it can be identified easily. For example,
an unwind across an exception boundary will appear as follows:

|  el1h_64_irq+0x6c/0x70
|  _raw_spin_unlock_irqrestore+0x10/0x60 (P)
|  __aarch64_insn_write+0x6c/0x90 (L)
|  aarch64_insn_patch_text_nosync+0x28/0x80

... with a (P) entry for pt_regs::pc, and an (L) entry for pt_regs:lr.

Note that the LR may be stale at the point of the exception, for example,
shortly after a return:

|  el1h_64_irq+0x6c/0x70
|  default_idle_call+0x34/0x180 (P)
|  default_idle_call+0x28/0x180 (L)
|  do_idle+0x204/0x268

... where the LR points a few instructions before the current PC.

This plays nicely with all the other unwind metadata tracking. With the
ftrace_graph profiler enabled globally, and kretprobes installed on
generic_handle_domain_irq() and do_interrupt_handler(), a backtrace triggered
by magic-sysrq + L reports:

| Call trace:
|  show_stack+0x20/0x40 (CF)
|  dump_stack_lvl+0x60/0x80 (F)
|  dump_stack+0x18/0x28
|  nmi_cpu_backtrace+0xfc/0x140
|  nmi_trigger_cpumask_backtrace+0x1c8/0x200
|  arch_trigger_cpumask_backtrace+0x20/0x40
|  sysrq_handle_showallcpus+0x24/0x38 (F)
|  __handle_sysrq+0xa8/0x1b0 (F)
|  handle_sysrq+0x38/0x50 (F)
|  pl011_int+0x460/0x5a8 (F)
|  __handle_irq_event_percpu+0x60/0x220 (F)
|  handle_irq_event+0x54/0xc0 (F)
|  handle_fasteoi_irq+0xa8/0x1d0 (F)
|  generic_handle_domain_irq+0x34/0x58 (F)
|  gic_handle_irq+0x54/0x140 (FK)
|  call_on_irq_stack+0x24/0x58 (F)
|  do_interrupt_handler+0x88/0xa0
|  el1_interrupt+0x34/0x68 (FK)
|  el1h_64_irq_handler+0x18/0x28
|  el1h_64_irq+0x6c/0x70
|  default_idle_call+0x34/0x180 (P)
|  default_idle_call+0x28/0x180 (L)
|  do_idle+0x204/0x268
|  cpu_startup_entry+0x3c/0x50 (F)
|  rest_init+0xe4/0xf0
|  start_kernel+0x744/0x750
|  __primary_switched+0x88/0x98

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241017092538.1859841-11-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2024-10-17 18:06:25 +01:00
Mark RutlandandCatalin Marinas 1454363098 arm64: pt_regs: swap 'unused' and 'pmr' fields
In subsequent patches we'll want to add an additional u64 to struct
pt_regs. To make space, this patch swaps the 'unused' and 'pmr' fields,
as the 'pmr' value only requires bits[7:0] and can safely fit into a
u32, which frees up a 64-bit unused field.

The 'lockdep_hardirqs' and 'exit_rcu' fields should eventually be moved
out of pt_regs and managed locally within entry-common.c, so I've left
those as-is for the moment.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241017092538.1859841-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2024-10-17 18:06:24 +01:00
Mark RutlandandCatalin Marinas 00d9597903 arm64: pt_regs: rename "pmr_save" -> "pmr"
The pt_regs::pmr_save field is weirdly named relative to all other
pt_regs fields, with a '_save' suffix that doesn't make anything clearer
and only leads to more typing to access the field.

Remove the '_save' suffix.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Puranjay Mohan <puranjay12@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20241017092538.1859841-4-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2024-10-17 18:06:24 +01:00
Mark RutlandandWill Deacon da59f1d051 arm64: entry: simplify kernel_exit logic
For historical reasons, the non-KPTI exception return path is duplicated for
EL1 and EL0, with the structure:

	.if \el == 0
	[ KPTI handling ]
	ldr     lr, [sp, #S_LR]
 	add	sp, sp, #PT_REGS_SIZE		// restore sp
	[ EL0 exception return workaround ]
	eret
	.else
	ldr     lr, [sp, #S_LR]
 	add	sp, sp, #PT_REGS_SIZE		// restore sp
	[ EL1 exception return workaround ]
	eret
	.endif
	sb

This would be simpler and clearer with the common portions factored out,
e.g.

	.if \el == 0
	[ KPTI handling ]
	.endif

	ldr     lr, [sp, #S_LR]
 	add	sp, sp, #PT_REGS_SIZE		// restore sp

	.if \el == 0
	[ EL0 exception return workaround ]
	.else
	[ EL1 exception return workaround ]
	.endif

	eret
	sb

This expands to the same code, but is simpler for a human to follow as
it avoids duplicates the restore of LR+SP, and makes it clear that the
ERET is associated with the SB.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20240116110221.420467-3-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2024-01-18 11:00:09 +00:00
Mark RutlandandWill Deacon 832dd634bd arm64: entry: fix ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
Currently the ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD workaround isn't
quite right, as it is supposed to be applied after the last explicit
memory access, but is immediately followed by an LDR.

The ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD workaround is used to
handle Cortex-A520 erratum 2966298 and Cortex-A510 erratum 3117295,
which are described in:

* https://developer.arm.com/documentation/SDEN2444153/0600/?lang=en
* https://developer.arm.com/documentation/SDEN1873361/1600/?lang=en

In both cases the workaround is described as:

| If pagetable isolation is disabled, the context switch logic in the
| kernel can be updated to execute the following sequence on affected
| cores before exiting to EL0, and after all explicit memory accesses:
|
| 1. A non-shareable TLBI to any context and/or address, including
|    unused contexts or addresses, such as a `TLBI VALE1 Xzr`.
|
| 2. A DSB NSH to guarantee completion of the TLBI.

The important part being that the TLBI+DSB must be placed "after all
explicit memory accesses".

Unfortunately, as-implemented, the TLBI+DSB is immediately followed by
an LDR, as we have:

| alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
| 	tlbi	vale1, xzr
| 	dsb	nsh
| alternative_else_nop_endif
| alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
| 	ldr	lr, [sp, #S_LR]
| 	add	sp, sp, #PT_REGS_SIZE		// restore sp
| 	eret
| alternative_else_nop_endif
|
| [ ... KPTI exception return path ... ]

This patch fixes this by reworking the logic to place the TLBI+DSB
immediately before the ERET, after all explicit memory accesses.

The ERET is currently in a separate alternative block, and alternatives
cannot be nested. To account for this, the alternative block for
ARM64_UNMAP_KERNEL_AT_EL0 is replaced with a single alternative branch
to skip the KPTI logic, with the new shape of the logic being:

| alternative_insn "b .L_skip_tramp_exit_\@", nop, ARM64_UNMAP_KERNEL_AT_EL0
| 	[ ... KPTI exception return path ... ]
| .L_skip_tramp_exit_\@:
|
| 	ldr	lr, [sp, #S_LR]
| 	add	sp, sp, #PT_REGS_SIZE		// restore sp
|
| alternative_if ARM64_WORKAROUND_SPECULATIVE_UNPRIV_LOAD
| 	tlbi	vale1, xzr
| 	dsb	nsh
| alternative_else_nop_endif
| 	eret

The new structure means that the workaround is only applied when KPTI is
not in use; this is fine as noted in the documented implications of the
erratum:

| Pagetable isolation between EL0 and higher level ELs prevents the
| issue from occurring.

... and as per the workaround description quoted above, the workaround
is only necessary "If pagetable isolation is disabled".

Fixes: 471470bc70 ("arm64: errata: Add Cortex-A520 speculative unprivileged load workaround")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20240116110221.420467-2-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2024-01-18 11:00:09 +00:00
Rob HerringandWill Deacon 546b7cde9b arm64: Rename ARM64_WORKAROUND_2966298
In preparation to apply ARM64_WORKAROUND_2966298 for multiple errata,
rename the kconfig and capability. No functional change.

Cc: stable@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20240110-arm-errata-a510-v1-1-d02bc51aeeee@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2024-01-12 12:51:33 +00:00
Rob HerringandWill Deacon 471470bc70 arm64: errata: Add Cortex-A520 speculative unprivileged load workaround
Implement the workaround for ARM Cortex-A520 erratum 2966298. On an
affected Cortex-A520 core, a speculatively executed unprivileged load
might leak data from a privileged load via a cache side channel. The
issue only exists for loads within a translation regime with the same
translation (e.g. same ASID and VMID). Therefore, the issue only affects
the return to EL0.

The workaround is to execute a TLBI before returning to EL0 after all
loads of privileged data. A non-shareable TLBI to any address is
sufficient.

The workaround isn't necessary if page table isolation (KPTI) is
enabled, but for simplicity it will be. Page table isolation should
normally be disabled for Cortex-A520 as it supports the CSV3 feature
and the E0PD feature (used when KASLR is enabled).

Cc: stable@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230921194156.1050055-2-robh@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
2023-09-29 16:31:33 +01:00
D Scott PhillipsandWill Deacon 5cd474e573 arm64: sdei: abort running SDEI handlers during crash
Interrupts are blocked in SDEI context, per the SDEI spec: "The client
interrupts cannot preempt the event handler." If we crashed in the SDEI
handler-running context (as with ACPI's AGDI) then we need to clean up the
SDEI state before proceeding to the crash kernel so that the crash kernel
can have working interrupts.

Track the active SDEI handler per-cpu so that we can COMPLETE_AND_RESUME
the handler, discarding the interrupted context.

Fixes: f5df269618 ("arm64: kernel: Add arch-specific SDEI entry code and CPU masking")
Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>
Cc: stable@vger.kernel.org
Reviewed-by: James Morse <james.morse@arm.com>
Tested-by: Mihai Carabas <mihai.carabas@oracle.com>
Link: https://lore.kernel.org/r/20230627002939.2758-1-scott@os.amperecomputing.com
Signed-off-by: Will Deacon <will@kernel.org>
2023-08-04 17:35:33 +01:00
Ard BiesheuvelandCatalin Marinas 211ceca377 arm64: entry: Simplify tramp_alias macro and tramp_exit routine
The tramp_alias macro constructs the virtual alias of a symbol in the
trampoline text mapping, based on its kernel text address, and does so
in a way that is more convoluted than necessary. So let's simplify that.

Also, now that the address of the vector table is kept in a per-CPU
variable, there is no need to defer the load and the assignment of
VBAR_EL1 to tramp_exit(). This means we can use a PC-relative reference
to the per-CPU variable instead of storing its absolute address in a
global variable in the trampoline rodata.

And given that tramp_alias no longer needs a temp register, this means
we can restore X30 earlier as well, and only leave X29 for tramp_exit()
to restore.

While at it, give some related symbols static linkage, considering that
they are only referenced from the object file that defines them.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230418143604.1176437-3-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-05-25 16:55:19 +01:00
Ard BiesheuvelandCatalin Marinas 0936243cab arm64: entry: Preserve/restore X29 even for compat tasks
Currently, the KPTI trampoline code for returning to user space takes
care to only preserve X29 into FAR_EL1 for native tasks, as compat tasks
don't have access to this register anyway, and so preserving it is not
necessary. It also means it does not need to be restored, and so we have
two code paths for returning back to user space: the native one that
restores X29 from FAR_EL1, and the compat one that leaves X29 clobbered,
containing the value of TTBR1_EL1, which carries a physical address
pointing somewhere into the kernel image.

This is needlessly complex, and given that FAR_EL1 becomes UNKNOWN after
an exception return anway, the only benefit of avoiding the preserve and
restore is that we can skip the system register write and read.

So let's simplify this, and collapse the two code paths into one that
always preserves X29 into FAR_EL1, and always restores it again after
the TTBR switch.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230418143604.1176437-2-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-05-25 16:55:19 +01:00
Catalin Marinas 156010ed9c Merge branches 'for-next/sysreg', 'for-next/sme', 'for-next/kselftest', 'for-next/misc', 'for-next/sme2', 'for-next/tpidr2', 'for-next/scs', 'for-next/compat-hwcap', 'for-next/ftrace', 'for-next/efi-boot-mmu-on', 'for-next/ptrauth' and 'for-next/pseudo-nmi', remote-tracking branch 'arm64/for-next/perf' into for-next/core
* arm64/for-next/perf:
  perf: arm_spe: Print the version of SPE detected
  perf: arm_spe: Add support for SPEv1.2 inverted event filtering
  perf: Add perf_event_attr::config3
  drivers/perf: fsl_imx8_ddr_perf: Remove set-but-not-used variable
  perf: arm_spe: Support new SPEv1.2/v8.7 'not taken' event
  perf: arm_spe: Use new PMSIDR_EL1 register enums
  perf: arm_spe: Drop BIT() and use FIELD_GET/PREP accessors
  arm64/sysreg: Convert SPE registers to automatic generation
  arm64: Drop SYS_ from SPE register defines
  perf: arm_spe: Use feature numbering for PMSEVFR_EL1 defines
  perf/marvell: Add ACPI support to TAD uncore driver
  perf/marvell: Add ACPI support to DDR uncore driver
  perf/arm-cmn: Reset DTM_PMU_CONFIG at probe
  drivers/perf: hisi: Extract initialization of "cpa_pmu->pmu"
  drivers/perf: hisi: Simplify the parameters of hisi_pmu_init()
  drivers/perf: hisi: Advertise the PERF_PMU_CAP_NO_EXCLUDE capability

* for-next/sysreg:
  : arm64 sysreg and cpufeature fixes/updates
  KVM: arm64: Use symbolic definition for ISR_EL1.A
  arm64/sysreg: Add definition of ISR_EL1
  arm64/sysreg: Add definition for ICC_NMIAR1_EL1
  arm64/cpufeature: Remove 4 bit assumption in ARM64_FEATURE_MASK()
  arm64/sysreg: Fix errors in 32 bit enumeration values
  arm64/cpufeature: Fix field sign for DIT hwcap detection

* for-next/sme:
  : SME-related updates
  arm64/sme: Optimise SME exit on syscall entry
  arm64/sme: Don't use streaming mode to probe the maximum SME VL
  arm64/ptrace: Use system_supports_tpidr2() to check for TPIDR2 support

* for-next/kselftest: (23 commits)
  : arm64 kselftest fixes and improvements
  kselftest/arm64: Don't require FA64 for streaming SVE+ZA tests
  kselftest/arm64: Copy whole EXTRA context
  kselftest/arm64: Fix enumeration of systems without 128 bit SME for SSVE+ZA
  kselftest/arm64: Fix enumeration of systems without 128 bit SME
  kselftest/arm64: Don't require FA64 for streaming SVE tests
  kselftest/arm64: Limit the maximum VL we try to set via ptrace
  kselftest/arm64: Correct buffer size for SME ZA storage
  kselftest/arm64: Remove the local NUM_VL definition
  kselftest/arm64: Verify simultaneous SSVE and ZA context generation
  kselftest/arm64: Verify that SSVE signal context has SVE_SIG_FLAG_SM set
  kselftest/arm64: Remove spurious comment from MTE test Makefile
  kselftest/arm64: Support build of MTE tests with clang
  kselftest/arm64: Initialise current at build time in signal tests
  kselftest/arm64: Don't pass headers to the compiler as source
  kselftest/arm64: Remove redundant _start labels from FP tests
  kselftest/arm64: Fix .pushsection for strings in FP tests
  kselftest/arm64: Run BTI selftests on systems without BTI
  kselftest/arm64: Fix test numbering when skipping tests
  kselftest/arm64: Skip non-power of 2 SVE vector lengths in fp-stress
  kselftest/arm64: Only enumerate power of two VLs in syscall-abi
  ...

* for-next/misc:
  : Miscellaneous arm64 updates
  arm64/mm: Intercept pfn changes in set_pte_at()
  Documentation: arm64: correct spelling
  arm64: traps: attempt to dump all instructions
  arm64: Apply dynamic shadow call stack patching in two passes
  arm64: el2_setup.h: fix spelling typo in comments
  arm64: Kconfig: fix spelling
  arm64: cpufeature: Use kstrtobool() instead of strtobool()
  arm64: Avoid repeated AA64MMFR1_EL1 register read on pagefault path
  arm64: make ARCH_FORCE_MAX_ORDER selectable

* for-next/sme2: (23 commits)
  : Support for arm64 SME 2 and 2.1
  arm64/sme: Fix __finalise_el2 SMEver check
  kselftest/arm64: Remove redundant _start labels from zt-test
  kselftest/arm64: Add coverage of SME 2 and 2.1 hwcaps
  kselftest/arm64: Add coverage of the ZT ptrace regset
  kselftest/arm64: Add SME2 coverage to syscall-abi
  kselftest/arm64: Add test coverage for ZT register signal frames
  kselftest/arm64: Teach the generic signal context validation about ZT
  kselftest/arm64: Enumerate SME2 in the signal test utility code
  kselftest/arm64: Cover ZT in the FP stress test
  kselftest/arm64: Add a stress test program for ZT0
  arm64/sme: Add hwcaps for SME 2 and 2.1 features
  arm64/sme: Implement ZT0 ptrace support
  arm64/sme: Implement signal handling for ZT
  arm64/sme: Implement context switching for ZT0
  arm64/sme: Provide storage for ZT0
  arm64/sme: Add basic enumeration for SME2
  arm64/sme: Enable host kernel to access ZT0
  arm64/sme: Manually encode ZT0 load and store instructions
  arm64/esr: Document ISS for ZT0 being disabled
  arm64/sme: Document SME 2 and SME 2.1 ABI
  ...

* for-next/tpidr2:
  : Include TPIDR2 in the signal context
  kselftest/arm64: Add test case for TPIDR2 signal frame records
  kselftest/arm64: Add TPIDR2 to the set of known signal context records
  arm64/signal: Include TPIDR2 in the signal context
  arm64/sme: Document ABI for TPIDR2 signal information

* for-next/scs:
  : arm64: harden shadow call stack pointer handling
  arm64: Stash shadow stack pointer in the task struct on interrupt
  arm64: Always load shadow stack pointer directly from the task struct

* for-next/compat-hwcap:
  : arm64: Expose compat ARMv8 AArch32 features (HWCAPs)
  arm64: Add compat hwcap SSBS
  arm64: Add compat hwcap SB
  arm64: Add compat hwcap I8MM
  arm64: Add compat hwcap ASIMDBF16
  arm64: Add compat hwcap ASIMDFHM
  arm64: Add compat hwcap ASIMDDP
  arm64: Add compat hwcap FPHP and ASIMDHP

* for-next/ftrace:
  : Add arm64 support for DYNAMICE_FTRACE_WITH_CALL_OPS
  arm64: avoid executing padding bytes during kexec / hibernation
  arm64: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
  arm64: ftrace: Update stale comment
  arm64: patching: Add aarch64_insn_write_literal_u64()
  arm64: insn: Add helpers for BTI
  arm64: Extend support for CONFIG_FUNCTION_ALIGNMENT
  ACPI: Don't build ACPICA with '-Os'
  Compiler attributes: GCC cold function alignment workarounds
  ftrace: Add DYNAMIC_FTRACE_WITH_CALL_OPS

* for-next/efi-boot-mmu-on:
  : Permit arm64 EFI boot with MMU and caches on
  arm64: kprobes: Drop ID map text from kprobes blacklist
  arm64: head: Switch endianness before populating the ID map
  efi: arm64: enter with MMU and caches enabled
  arm64: head: Clean the ID map and the HYP text to the PoC if needed
  arm64: head: avoid cache invalidation when entering with the MMU on
  arm64: head: record the MMU state at primary entry
  arm64: kernel: move identity map out of .text mapping
  arm64: head: Move all finalise_el2 calls to after __enable_mmu

* for-next/ptrauth:
  : arm64 pointer authentication cleanup
  arm64: pauth: don't sign leaf functions
  arm64: unify asm-arch manipulation

* for-next/pseudo-nmi:
  : Pseudo-NMI code generation optimisations
  arm64: irqflags: use alternative branches for pseudo-NMI logic
  arm64: add ARM64_HAS_GIC_PRIO_RELAXED_SYNC cpucap
  arm64: make ARM64_HAS_GIC_PRIO_MASKING depend on ARM64_HAS_GIC_CPUIF_SYSREGS
  arm64: rename ARM64_HAS_IRQ_PRIO_MASKING to ARM64_HAS_GIC_PRIO_MASKING
  arm64: rename ARM64_HAS_SYSREG_GIC_CPUIF to ARM64_HAS_GIC_CPUIF_SYSREGS
2023-02-10 18:51:49 +00:00
Mark RutlandandCatalin Marinas 8bf0a8048b arm64: add ARM64_HAS_GIC_PRIO_RELAXED_SYNC cpucap
When Priority Mask Hint Enable (PMHE) == 0b1, the GIC may use the PMR
value to determine whether to signal an IRQ to a PE, and consequently
after a change to the PMR value, a DSB SY may be required to ensure that
interrupts are signalled to a CPU in finite time. When PMHE == 0b0,
interrupts are always signalled to the relevant PE, and all masking
occurs locally, without requiring a DSB SY.

Since commit:

  f226650494 ("arm64: Relax ICC_PMR_EL1 accesses when ICC_CTLR_EL1.PMHE is clear")

... we handle this dynamically: in most cases a static key is used to
determine whether to issue a DSB SY, but the entry code must read from
ICC_CTLR_EL1 as static keys aren't accessible from plain assembly.

It would be much nicer to use an alternative instruction sequence for
the DSB, as this would avoid the need to read from ICC_CTLR_EL1 in the
entry code, and for most other code this will result in simpler code
generation with fewer instructions and fewer branches.

This patch adds a new ARM64_HAS_GIC_PRIO_RELAXED_SYNC cpucap which is
only set when ICC_CTLR_EL1.PMHE == 0b0 (and GIC priority masking is in
use). This allows us to replace the existing users of the
`gic_pmr_sync` static key with alternative sequences which default to a
DSB SY and are relaxed to a NOP when PMHE is not in use.

The entry assembly management of the PMR is slightly restructured to use
a branch (rather than multiple NOPs) when priority masking is not in
use. This is more in keeping with other alternatives in the entry
assembly, and permits the use of a separate alternatives for the
PMHE-dependent DSB SY (and removal of the conditional branch this
currently requires). For consistency I've adjusted both the save and
restore paths.

According to bloat-o-meter, when building defconfig +
CONFIG_ARM64_PSEUDO_NMI=y this shrinks the kernel text by ~4KiB:

| add/remove: 4/2 grow/shrink: 42/310 up/down: 332/-5032 (-4700)

The resulting vmlinux is ~66KiB smaller, though the resulting Image size
is unchanged due to padding and alignment:

| [mark@lakrids:~/src/linux]% ls -al vmlinux-*
| -rwxr-xr-x 1 mark mark 137508344 Jan 17 14:11 vmlinux-after
| -rwxr-xr-x 1 mark mark 137575440 Jan 17 13:49 vmlinux-before
| [mark@lakrids:~/src/linux]% ls -al Image-*
| -rw-r--r-- 1 mark mark 38777344 Jan 17 14:11 Image-after
| -rw-r--r-- 1 mark mark 38777344 Jan 17 13:49 Image-before

Prior to this patch we did not verify the state of ICC_CTLR_EL1.PMHE on
secondary CPUs. As of this patch this is verified by the cpufeature code
when using GIC priority masking (i.e. when using pseudo-NMIs).

Note that since commit:

  7e3a57fa6c ("arm64: Document ICC_CTLR_EL3.PMHE setting requirements")

... Documentation/arm64/booting.rst specifies:

|      - ICC_CTLR_EL3.PMHE (bit 6) must be set to the same value across
|        all CPUs the kernel is executing on, and must stay constant
|        for the lifetime of the kernel.

... so that should not adversely affect any compliant systems, and as
we'll only check for the absense of PMHE when using pseudo-NMIs, this
will only fire when such mismatch will adversely affect the system.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230130145429.903791-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-01-31 16:06:17 +00:00
Mark RutlandandCatalin Marinas c888b7bd91 arm64: rename ARM64_HAS_IRQ_PRIO_MASKING to ARM64_HAS_GIC_PRIO_MASKING
Subsequent patches will add more GIC-related cpucaps. When we do so, it
would be nice to give them a consistent HAS_GIC_* prefix.

In preparation for doing so, this patch renames the existing
ARM64_HAS_IRQ_PRIO_MASKING cap to ARM64_HAS_GIC_PRIO_MASKING.

The cpucaps file was hand-modified; all other changes were scripted
with:

  find . -type f -name '*.[chS]' -print0 | \
    xargs -0 sed -i 's/ARM64_HAS_IRQ_PRIO_MASKING/ARM64_HAS_GIC_PRIO_MASKING/'

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230130145429.903791-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-01-31 16:06:17 +00:00
Ard BiesheuvelandCatalin Marinas 59b37fe52f arm64: Stash shadow stack pointer in the task struct on interrupt
Instead of reloading the shadow call stack pointer from the ordinary
stack, which may be vulnerable to the kind of gadget based attacks
shadow call stacks were designed to prevent, let's store a task's shadow
call stack pointer in the task struct when switching to the shadow IRQ
stack.

Given that currently, the task_struct::scs_sp field is only used to
preserve the shadow call stack pointer while a task is scheduled out or
running in user space, reusing this field to preserve and restore it
while running off the IRQ stack must be safe, as those occurrences are
guaranteed to never overlap. (The stack switching logic only switches
stacks when running from the task stack, and so the value being saved
here always corresponds to the task mode shadow stack)

While at it, fold a mov/add/mov sequence into a single add.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20230109174800.3286265-3-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-01-20 14:26:18 +00:00
Ard BiesheuvelandCatalin Marinas 2198d07c50 arm64: Always load shadow stack pointer directly from the task struct
All occurrences of the scs_load macro load the value of the shadow call
stack pointer from the task which is current at that point. So instead
of taking a task struct register argument in the scs_load macro to
specify the task struct to load from, let's always reference the current
task directly. This should make it much harder to exploit any
instruction sequences reloading the shadow call stack pointer register
from memory.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230109174800.3286265-2-ardb@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-01-20 14:26:18 +00:00
Ard BiesheuvelandWill Deacon 01ab991fc0 arm64: Enable data independent timing (DIT) in the kernel
The ARM architecture revision v8.4 introduces a data independent timing
control (DIT) which can be set at any exception level, and instructs the
CPU to avoid optimizations that may result in a correlation between the
execution time of certain instructions and the value of the data they
operate on.

The DIT bit is part of PSTATE, and is therefore context switched as
usual, given that it becomes part of the saved program state (SPSR) when
taking an exception. We have also defined a hwcap for DIT, and so user
space can discover already whether or nor DIT is available. This means
that, as far as user space is concerned, DIT is wired up and fully
functional.

In the kernel, however, we never bothered with DIT: we disable at it
boot (i.e., INIT_PSTATE_EL1 has DIT cleared) and ignore the fact that we
might run with DIT enabled if user space happened to set it.

Currently, we have no idea whether or not running privileged code with
DIT disabled on a CPU that implements support for it may result in a
side channel that exposes privileged data to unprivileged user space
processes, so let's be cautious and just enable DIT while running in the
kernel if supported by all CPUs.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Adam Langley <agl@google.com>
Link: https://lore.kernel.org/all/YwgCrqutxmX0W72r@gmail.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20221107172400.1851434-1-ardb@kernel.org
[will: Removed cpu_has_dit() as per Mark's suggestion on the list]
Signed-off-by: Will Deacon <will@kernel.org>
2022-11-08 14:55:10 +00:00
Mark RutlandandCatalin Marinas 4c0bd995d7 arm64: alternatives: have callbacks take a cap
Today, callback alternatives are special-cased within
__apply_alternatives(), and are applied alongside patching for system
capabilities as ARM64_NCAPS is not part of the boot_capabilities feature
mask.

This special-casing is less than ideal. Giving special meaning to
ARM64_NCAPS for this requires some structures and loops to use
ARM64_NCAPS + 1 (AKA ARM64_NPATCHABLE), while others use ARM64_NCAPS.
It's also not immediately clear callback alternatives are only applied
when applying alternatives for system-wide features.

To make this a bit clearer, changes the way that callback alternatives
are identified to remove the special-casing of ARM64_NCAPS, and to allow
callback alternatives to be associated with a cpucap as with all other
alternatives.

New cpucaps, ARM64_ALWAYS_BOOT and ARM64_ALWAYS_SYSTEM are added which
are always detected alongside boot cpu capabilities and system
capabilities respectively. All existing callback alternatives are made
to use ARM64_ALWAYS_SYSTEM, and so will be patched at the same point
during the boot flow as before.

Subsequent patches will make more use of these new cpucaps.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220912162210.3626215-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2022-09-16 17:15:03 +01:00