| Commit message (Collapse) | Author | Age | Files | Lines |
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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>
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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: 471470bc7052 ("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>
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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>
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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>
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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: f5df26961853 ("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>
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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>
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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>
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'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
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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:
f226650494c6aa87 ("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:
7e3a57fa6ca831fa ("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>
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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>
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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>
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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>
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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>
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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>
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Replace wrong 'FIQ EL1h' comment with 'FIQ EL1t'.
Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Link: https://lore.kernel.org/r/20220721030531.21234-1-Kuan-Ying.Lee@mediatek.com
Signed-off-by: Will Deacon <will@kernel.org>
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Get rid of some clunky open coded arithmetic on section addresses, by
emitting the trampoline data variables into a separate, dedicated r/o
data section, and putting it at the next page boundary. This way, we can
access the literals via single LDR instruction.
While at it, get rid of other, implicit literals, and use ADRP/ADD or
MOVZ/MOVK sequences, as appropriate. Note that the latter are only
supported for CONFIG_RELOCATABLE=n (which is usually the case if
CONFIG_RANDOMIZE_BASE=n), so update the CPP conditionals to reflect
this.
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220622161010.3845775-1-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
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On arm64 we always call stackleak_erase() on a task stack, and never
call it on another stack. We can avoid some redundant work by using
stackleak_erase_on_task_stack(), telling the stackleak code that it's
being called on a task stack.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Popov <alex.popov@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220427173128.2603085-14-mark.rutland@arm.com
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Merge in the latest Spectre mess to fix up conflicts with what was
already queued for 5.18 when the embargo finally lifted.
* for-next/spectre-bhb: (21 commits)
arm64: Do not include __READ_ONCE() block in assembly files
arm64: proton-pack: Include unprivileged eBPF status in Spectre v2 mitigation reporting
arm64: Use the clearbhb instruction in mitigations
KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated
arm64: Mitigate spectre style branch history side channels
arm64: proton-pack: Report Spectre-BHB vulnerabilities as part of Spectre-v2
arm64: Add percpu vectors for EL1
arm64: entry: Add macro for reading symbol addresses from the trampoline
arm64: entry: Add vectors that have the bhb mitigation sequences
arm64: entry: Add non-kpti __bp_harden_el1_vectors for mitigations
arm64: entry: Allow the trampoline text to occupy multiple pages
arm64: entry: Make the kpti trampoline's kpti sequence optional
arm64: entry: Move trampoline macros out of ifdef'd section
arm64: entry: Don't assume tramp_vectors is the start of the vectors
arm64: entry: Allow tramp_alias to access symbols after the 4K boundary
arm64: entry: Move the trampoline data page before the text page
arm64: entry: Free up another register on kpti's tramp_exit path
arm64: entry: Make the trampoline cleanup optional
KVM: arm64: Allow indirect vectors to be used without SPECTRE_V3A
arm64: spectre: Rename spectre_v4_patch_fw_mitigation_conduit
...
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Future CPUs may implement a clearbhb instruction that is sufficient
to mitigate SpectreBHB. CPUs that implement this instruction, but
not CSV2.3 must be affected by Spectre-BHB.
Add support to use this instruction as the BHB mitigation on CPUs
that support it. The instruction is in the hint space, so it will
be treated by a NOP as older CPUs.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The Spectre-BHB workaround adds a firmware call to the vectors. This
is needed on some CPUs, but not others. To avoid the unaffected CPU in
a big/little pair from making the firmware call, create per cpu vectors.
The per-cpu vectors only apply when returning from EL0.
Systems using KPTI can use the canonical 'full-fat' vectors directly at
EL1, the trampoline exit code will switch to this_cpu_vector on exit to
EL0. Systems not using KPTI should always use this_cpu_vector.
this_cpu_vector will point at a vector in tramp_vecs or
__bp_harden_el1_vectors, depending on whether KPTI is in use.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The trampoline code needs to use the address of symbols in the wider
kernel, e.g. vectors. PC-relative addressing wouldn't work as the
trampoline code doesn't run at the address the linker expected.
tramp_ventry uses a literal pool, unless CONFIG_RANDOMIZE_BASE is
set, in which case it uses the data page as a literal pool because
the data page can be unmapped when running in user-space, which is
required for CPUs vulnerable to meltdown.
Pull this logic out as a macro, instead of adding a third copy
of it.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Some CPUs affected by Spectre-BHB need a sequence of branches, or a
firmware call to be run before any indirect branch. This needs to go
in the vectors. No CPU needs both.
While this can be patched in, it would run on all CPUs as there is a
single set of vectors. If only one part of a big/little combination is
affected, the unaffected CPUs have to run the mitigation too.
Create extra vectors that include the sequence. Subsequent patches will
allow affected CPUs to select this set of vectors. Later patches will
modify the loop count to match what the CPU requires.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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kpti is an optional feature, for systems not using kpti a set of
vectors for the spectre-bhb mitigations is needed.
Add another set of vectors, __bp_harden_el1_vectors, that will be
used if a mitigation is needed and kpti is not in use.
The EL1 ventries are repeated verbatim as there is no additional
work needed for entry from EL1.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Adding a second set of vectors to .entry.tramp.text will make it
larger than a single 4K page.
Allow the trampoline text to occupy up to three pages by adding two
more fixmap slots. Previous changes to tramp_valias allowed it to reach
beyond a single page.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Spectre-BHB needs to add sequences to the vectors. Having one global
set of vectors is a problem for big/little systems where the sequence
is costly on cpus that are not vulnerable.
Making the vectors per-cpu in the style of KVM's bh_harden_hyp_vecs
requires the vectors to be generated by macros.
Make the kpti re-mapping of the kernel optional, so the macros can be
used without kpti.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The macros for building the kpti trampoline are all behind
CONFIG_UNMAP_KERNEL_AT_EL0, and in a region that outputs to the
.entry.tramp.text section.
Move the macros out so they can be used to generate other kinds of
trampoline. Only the symbols need to be guarded by
CONFIG_UNMAP_KERNEL_AT_EL0 and appear in the .entry.tramp.text section.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The tramp_ventry macro uses tramp_vectors as the address of the vectors
when calculating which ventry in the 'full fat' vectors to branch to.
While there is one set of tramp_vectors, this will be true.
Adding multiple sets of vectors will break this assumption.
Move the generation of the vectors to a macro, and pass the start
of the vectors as an argument to tramp_ventry.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Systems using kpti enter and exit the kernel through a trampoline mapping
that is always mapped, even when the kernel is not. tramp_valias is a macro
to find the address of a symbol in the trampoline mapping.
Adding extra sets of vectors will expand the size of the entry.tramp.text
section to beyond 4K. tramp_valias will be unable to generate addresses
for symbols beyond 4K as it uses the 12 bit immediate of the add
instruction.
As there are now two registers available when tramp_alias is called,
use the extra register to avoid the 4K limit of the 12 bit immediate.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The trampoline code has a data page that holds the address of the vectors,
which is unmapped when running in user-space. This ensures that with
CONFIG_RANDOMIZE_BASE, the randomised address of the kernel can't be
discovered until after the kernel has been mapped.
If the trampoline text page is extended to include multiple sets of
vectors, it will be larger than a single page, making it tricky to
find the data page without knowing the size of the trampoline text
pages, which will vary with PAGE_SIZE.
Move the data page to appear before the text page. This allows the
data page to be found without knowing the size of the trampoline text
pages. 'tramp_vectors' is used to refer to the beginning of the
.entry.tramp.text section, do that explicitly.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Kpti stashes x30 in far_el1 while it uses x30 for all its work.
Making the vectors a per-cpu data structure will require a second
register.
Allow tramp_exit two registers before it unmaps the kernel, by
leaving x30 on the stack, and stashing x29 in far_el1.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Subsequent patches will add additional sets of vectors that use
the same tricks as the kpti vectors to reach the full-fat vectors.
The full-fat vectors contain some cleanup for kpti that is patched
in by alternatives when kpti is in use. Once there are additional
vectors, the cleanup will be needed in more cases.
But on big/little systems, the cleanup would be harmful if no
trampoline vector were in use. Instead of forcing CPUs that don't
need a trampoline vector to use one, make the trampoline cleanup
optional.
Entry at the top of the vectors will skip the cleanup. The trampoline
vectors can then skip the first instruction, triggering the cleanup
to run.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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The spectre-v4 sequence includes an SMC from the assembly entry code.
spectre_v4_patch_fw_mitigation_conduit is the patching callback that
generates an HVC or SMC depending on the SMCCC conduit type.
As this isn't specific to spectre-v4, rename it
smccc_patch_fw_mitigation_conduit so it can be re-used.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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Subsequent patches add even more code to the ventry slots.
Ensure kernels that overflow a ventry slot don't get built.
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
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* for-next/mte:
docs: sysfs-devices-system-cpu: document "asymm" value for mte_tcf_preferred
arm64/mte: Remove asymmetric mode from the prctl() interface
kasan: fix a missing header include of static_keys.h
arm64/mte: Add userspace interface for enabling asymmetric mode
arm64/mte: Add hwcap for asymmetric mode
arm64/mte: Add a little bit of documentation for mte_update_sctlr_user()
arm64/mte: Document ABI for asymmetric mode
arm64: mte: avoid clearing PSTATE.TCO on entry unless necessary
kasan: split kasan_*enabled() functions into a separate header
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On some microarchitectures, clearing PSTATE.TCO is expensive. Clearing
TCO is only necessary if in-kernel MTE is enabled, or if MTE is
enabled in the userspace process in synchronous (or, soon, asymmetric)
mode, because we do not report uaccess faults to userspace in none
or asynchronous modes. Therefore, adjust the kernel entry code to
clear TCO only if necessary.
Because it is now possible to switch to a task in which TCO needs to
be clear from a task in which TCO is set, we also need to do the same
thing on task switch.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I52d82a580bd0500d420be501af2c35fa8c90729e
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20220219012945.894950-2-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>
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Arm64 pseudo-NMI feature code brings some additional nops
when CONFIG_ARM64_PSEUDO_NMI is not set, which is not
necessary. So add necessary ifdeffery to avoid it.
Signed-off-by: He Ying <heying24@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220112032410.29231-1-heying24@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
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Use SDEI_EV_FAILED instead of open coding the 1 to make it clearer how
SDEI_EVENT_COMPLETE vs. SDEI_EVENT_COMPLETE_AND_RESUME is selected.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20211118201811.2974922-1-f.fainelli@gmail.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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It is not necessary to write to GCR_EL1 on every kernel entry and
exit when HW tag-based KASAN is disabled because the kernel will not
execute any IRG instructions in that mode. Since accessing GCR_EL1
can be expensive on some microarchitectures, avoid doing so by moving
the access to task switch when HW tag-based KASAN is disabled.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I78e90d60612a94c24344526f476ac4ff216e10d2
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210924010655.2886918-1-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>
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* for-next/entry:
: More entry.S clean-ups and conversion to C.
arm64: entry: call exit_to_user_mode() from C
arm64: entry: move bulk of ret_to_user to C
arm64: entry: clarify entry/exit helpers
arm64: entry: consolidate entry/exit helpers
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When handling an exception from EL0, we perform the entry work in that
exception's C handler, and once the C handler has finished, we return
back to the entry assembly. Subsequently in the common `ret_to_user`
assembly we perform the exit work that balances with the entry work.
This can be somewhat difficult to follow, and makes it hard to rework
the return paths (e.g. to pass additional context to the exit code, or
to have exception return logic for specific exceptions).
This patch reworks the entry code such that each EL0 C exception handler
is responsible for both the entry and exit work. This clearly balances
the two (and will permit additional variation in future), and avoids an
unnecessary bounce between assembly and C in the common case, leaving
`ret_from_fork` as the only place assembly has to call the exit code.
This means that the exit work is now inlined into the C handler, which
is already the case for the entry work, and allows the compiler to
generate better code (e.g. by immediately returning when there is no
exit work to perform).
To align with other exception entry/exit helpers, enter_from_user_mode()
is updated to take the EL0 pt_regs as a parameter, though this is
currently unused.
There should be no functional change as a result of this patch. However,
this should lead to slightly better backtraces when an error is
encountered within do_notify_resume(), as the C handler should appear in
the backtrace, indicating the specific exception that the kernel was
entered with.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
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: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20210802140733.52716-5-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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In `ret_to_user` we perform some conditional work depending on the
thread flags, then perform some IRQ/context tracking which is intended
to balance with the IRQ/context tracking performed in the entry C code.
For simplicity and consistency, it would be preferable to move this all
to C. As a step towards that, this patch moves the conditional work and
IRQ/context tracking into a C helper function. To aid bisectability,
this is called from the `ret_to_user` assembly, and a subsequent patch
will move the call to C code.
As local_daif_mask() handles all necessary tracing and PMR manipulation,
we no longer need to handle this explicitly. As we call
exit_to_user_mode() directly, the `user_enter_irqoff` macro is no longer
used, and can be removed. As enter_from_user_mode() and
exit_to_user_mode() are no longer called from assembly, these can be
made static, and as these are typically very small, they are marked
__always_inline to avoid the overhead of a function call.
For now, enablement of single-step is left in entry.S, and for this we
still need to read the flags in ret_to_user(). It is safe to read this
separately as TIF_SINGLESTEP is not part of _TIF_WORK_MASK.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
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: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20210802140733.52716-4-mark.rutland@arm.com
[catalin.marinas@arm.com: removed unused gic_prio_kentry_setup macro]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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remote-tracking branch 'arm64/for-next/perf' into for-next/core
* arm64/for-next/perf:
arm64/perf: Replace '0xf' instances with ID_AA64DFR0_PMUVER_IMP_DEF
* for-next/mte:
: Miscellaneous MTE improvements.
arm64/cpufeature: Optionally disable MTE via command-line
arm64: kasan: mte: remove redundant mte_report_once logic
arm64: kasan: mte: use a constant kernel GCR_EL1 value
arm64: avoid double ISB on kernel entry
arm64: mte: optimize GCR_EL1 modification on kernel entry/exit
Documentation: document the preferred tag checking mode feature
arm64: mte: introduce a per-CPU tag checking mode preference
arm64: move preemption disablement to prctl handlers
arm64: mte: change ASYNC and SYNC TCF settings into bitfields
arm64: mte: rename gcr_user_excl to mte_ctrl
arm64: mte: avoid TFSRE0_EL1 related operations unless in async mode
* for-next/misc:
: Miscellaneous updates.
arm64: Do not trap PMSNEVFR_EL1
arm64: mm: fix comment typo of pud_offset_phys()
arm64: signal32: Drop pointless call to sigdelsetmask()
arm64/sve: Better handle failure to allocate SVE register storage
arm64: Document the requirement for SCR_EL3.HCE
arm64: head: avoid over-mapping in map_memory
arm64/sve: Add a comment documenting the binutils needed for SVE asm
arm64/sve: Add some comments for sve_save/load_state()
arm64: replace in_irq() with in_hardirq()
arm64: mm: Fix TLBI vs ASID rollover
arm64: entry: Add SYM_CODE annotation for __bad_stack
arm64: fix typo in a comment
arm64: move the (z)install rules to arch/arm64/Makefile
arm64/sve: Make fpsimd_bind_task_to_cpu() static
arm64: unnecessary end 'return;' in void functions
arm64/sme: Document boot requirements for SME
arm64: use __func__ to get function name in pr_err
arm64: SSBS/DIT: print SSBS and DIT bit when printing PSTATE
arm64: cpufeature: Use defined macro instead of magic numbers
arm64/kexec: Test page size support with new TGRAN range values
* for-next/kselftest:
: Kselftest additions for arm64.
kselftest/arm64: signal: Add a TODO list for signal handling tests
kselftest/arm64: signal: Add test case for SVE register state in signals
kselftest/arm64: signal: Verify that signals can't change the SVE vector length
kselftest/arm64: signal: Check SVE signal frame shows expected vector length
kselftest/arm64: signal: Support signal frames with SVE register data
kselftest/arm64: signal: Add SVE to the set of features we can check for
kselftest/arm64: pac: Fix skipping of tests on systems without PAC
kselftest/arm64: mte: Fix misleading output when skipping tests
kselftest/arm64: Add a TODO list for floating point tests
kselftest/arm64: Add tests for SVE vector configuration
kselftest/arm64: Validate vector lengths are set in sve-probe-vls
kselftest/arm64: Provide a helper binary and "library" for SVE RDVL
kselftest/arm64: Ignore check_gcr_el1_cswitch binary
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When converting arm64 to modern assembler annotations __bad_stack was left
as a raw local label without annotations. While this will have little if
any practical impact at present it may cause issues in the future if we
start using the annotations for things like reliable stack trace. Add
SYM_CODE annotations to fix this.
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210804181710.19059-1-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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When KASAN_HW_TAGS is selected, KASAN is enabled at boot time, and the
hardware supports MTE, we'll initialize `kernel_gcr_excl` with a value
dependent on KASAN_TAG_MAX. While the resulting value is a constant
which depends on KASAN_TAG_MAX, we have to perform some runtime work to
generate the value, and have to read the value from memory during the
exception entry path. It would be better if we could generate this as a
constant at compile-time, and use it as such directly.
Early in boot within __cpu_setup(), we initialize GCR_EL1 to a safe
value, and later override this with the value required by KASAN. If
CONFIG_KASAN_HW_TAGS is not selected, or if KASAN is disabeld at boot
time, the kernel will not use IRG instructions, and so the initial value
of GCR_EL1 is does not matter to the kernel. Thus, we can instead have
__cpu_setup() initialize GCR_EL1 to a value consistent with
KASAN_TAG_MAX, and avoid the need to re-initialize it during hotplug and
resume form suspend.
This patch makes arem64 use a compile-time constant KERNEL_GCR_EL1
value, which is compatible with KASAN_HW_TAGS when this is selected.
This removes the need to re-initialize GCR_EL1 dynamically, and acts as
an optimization to the entry assembly, which no longer needs to load
this value from memory. The redundant initialization hooks are removed.
In order to do this, KASAN_TAG_MAX needs to be visible outside of the
core KASAN code. To do this, I've moved the KASAN_TAG_* values into
<linux/kasan-tags.h>.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20210714143843.56537-3-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Although an ISB is required in order to make the MTE-related system
register update to GCR_EL1 effective, and the same is true for
PAC-related updates to SCTLR_EL1 or APIAKey{Hi,Lo}_EL1, we issue two
ISBs on machines that support both features while we only need to
issue one. To avoid the unnecessary additional ISB, remove the ISBs
from the PAC and MTE-specific alternative blocks and add a couple
of additional blocks that cause us to only execute one ISB if both
features are supported.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Idee7e8114d5ae5a0b171d06220a0eb4bb015a51c
Link: https://lore.kernel.org/r/20210727205439.2557419-1-pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Accessing GCR_EL1 and issuing an ISB can be expensive on some
microarchitectures. Although we must write to GCR_EL1, we can
restructure the code to avoid reading from it because the new value
can be derived entirely from the exclusion mask, which is already in
a GPR. Do so.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/I560a190a74176ca4cc5191dad08f77f6b1577c75
Link: https://lore.kernel.org/r/20210714013638.3995315-1-pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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We are going to use this field to store more data. To prepare for
that, rename it and change the users to rely on the bit position of
gcr_user_excl in mte_ctrl.
Link: https://linux-review.googlesource.com/id/Ie1fd18e480100655f5d22137f5b22f4f3a9f9e2e
Signed-off-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210727205300.2554659-2-pcc@google.com
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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There is no reason to touch TFSRE0_EL1 nor issue a DSB unless our task
is in asynchronous mode. Since these operations (especially the DSB) may
be expensive on certain microarchitectures, only perform them if
necessary.
Furthermore, stop clearing TFSRE0_EL1 on entry because it will be
cleared on exit and it is not necessary to have any particular value in
TFSRE0_EL1 between entry and exit.
Signed-off-by: Peter Collingbourne <pcc@google.com>
Link: https://linux-review.googlesource.com/id/Ib353a63e3d0abc2b0b008e96aa2d9692cfc1b815
Link: https://lore.kernel.org/r/20210709023532.2133673-1-pcc@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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The never-ending entry.S refactoring continues, putting us in a much
better place wrt compiler instrumentation whilst moving more of the code
into C.
* for-next/entry:
arm64: idle: don't instrument idle code with KCOV
arm64: entry: don't instrument entry code with KCOV
arm64: entry: make NMI entry/exit functions static
arm64: entry: split SDEI entry
arm64: entry: split bad stack entry
arm64: entry: fold el1_inv() into el1h_64_sync_handler()
arm64: entry: handle all vectors with C
arm64: entry: template the entry asm functions
arm64: entry: improve bad_mode()
arm64: entry: move bad_mode() to entry-common.c
arm64: entry: consolidate EL1 exception returns
arm64: entry: organise entry vectors consistently
arm64: entry: organise entry handlers consistently
arm64: entry: convert IRQ+FIQ handlers to C
arm64: entry: add a call_on_irq_stack helper
arm64: entry: move NMI preempt logic to C
arm64: entry: move arm64_preempt_schedule_irq to entry-common.c
arm64: entry: convert SError handlers to C
arm64: entry: unmask IRQ+FIQ after EL0 handling
arm64: remove redundant local_daif_mask() in bad_mode()
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We have 16 architectural exception vectors, and depending on kernel
configuration we handle 8 or 12 of these with C code, with the remaining
8 or 4 of these handled as special cases in the entry assembly.
It would be nicer if the entry assembly were uniform for all exceptions,
and we deferred any specific handling of the exceptions to C code. This
way the entry assembly can be more easily templated without ifdeffery or
special cases, and it's easier to modify the handling of these cases in
future (e.g. to dump additional registers other context).
This patch reworks the entry code so that we always have a C handler for
every architectural exception vector, with the entry assembly being
completely uniform. We now have to handle exceptions from EL1t and EL1h,
and also have to handle exceptions from AArch32 even when the kernel is
built without CONFIG_COMPAT. To make this clear and to simplify
templating, we rename the top-level exception handlers with a consistent
naming scheme:
asm: <el+sp>_<regsize>_<type>
c: <el+sp>_<regsize>_<type>_handler
.. where:
<el+sp> is `el1t`, `el1h`, or `el0t`
<regsize> is `64` or `32`
<type> is `sync`, `irq`, `fiq`, or `error`
... e.g.
asm: el1h_64_sync
c: el1h_64_sync_handler
... with lower-level handlers simply using "el1" and "compat" as today.
For unexpected exceptions, this information is passed to
__panic_unhandled(), so it can report the specific vector an unexpected
exception was taken from, e.g.
| Unhandled 64-bit el1t sync exception
For vectors we never expect to enter legitimately, the C code is
generated using a macro to avoid code duplication. The exceptions are
handled via __panic_unhandled(), replacing bad_mode() (which is
removed).
The `kernel_ventry` and `entry_handler` assembly macros are updated to
handle the new naming scheme. In theory it should be possible to
generate the entry functions at the same time as the vectors using a
single table, but this will require reworking the linker script to split
the two into separate sections, so for now we have separate tables.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-15-mark.rutland@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
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