linux.git/arch/arm64/include, branch v5.17

arm64: fix clang warning about TRAMP_VALIAS

2022-03-18T13:48:28+00:00

The newly introduced TRAMP_VALIAS definition causes a build warning
with clang-14:

arch/arm64/include/asm/vectors.h:66:31: error: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Werror,-Wnull-pointer-arithmetic]
                return (char *)TRAMP_VALIAS + SZ_2K * slot;

Change the addition to something clang does not complain about.

Fixes: bd09128d16fa ("arm64: Add percpu vectors for EL1")
Signed-off-by: Arnd Bergmann 
Acked-by: James Morse 
Link: https://lore.kernel.org/r/20220316183833.1563139-1-arnd@kernel.org
Signed-off-by: Catalin Marinas

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2022-03-09T22:30:09+00:00

Pull arm64 build fix from Catalin Marinas:
 "Fix kernel build with clang LTO after the inclusion of the Spectre BHB
  arm64 mitigations"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: Do not include __READ_ONCE() block in assembly files

arm64: Do not include __READ_ONCE() block in assembly files

2022-03-09T21:56:50+00:00

When building arm64 defconfig + CONFIG_LTO_CLANG_{FULL,THIN}=y after
commit 558c303c9734 ("arm64: Mitigate spectre style branch history side
channels"), the following error occurs:

  :4:2: error: invalid fixup for movz/movk instruction
   mov w0, #ARM_SMCCC_ARCH_WORKAROUND_3
   ^

Marc figured out that moving "#include " in
include/linux/arm-smccc.h into a !__ASSEMBLY__ block resolves it. The
full include chain with CONFIG_LTO=y from include/linux/arm-smccc.h:

include/linux/init.h
include/linux/compiler.h
arch/arm64/include/asm/rwonce.h
arch/arm64/include/asm/alternative-macros.h
arch/arm64/include/asm/assembler.h

The asm/alternative-macros.h include in asm/rwonce.h only happens when
CONFIG_LTO is set, which ultimately casues asm/assembler.h to be
included before the definition of ARM_SMCCC_ARCH_WORKAROUND_3. As a
result, the preprocessor does not expand ARM_SMCCC_ARCH_WORKAROUND_3 in
__mitigate_spectre_bhb_fw, which results in the error above.

Avoid this problem by just avoiding the CONFIG_LTO=y __READ_ONCE() block
in asm/rwonce.h with assembly files, as nothing in that block is useful
to assembly files, which allows ARM_SMCCC_ARCH_WORKAROUND_3 to be
properly expanded with CONFIG_LTO=y builds.

Fixes: e35123d83ee3 ("arm64: lto: Strengthen READ_ONCE() to acquire when CONFIG_LTO=y")
Cc:  # 5.11.x
Link: https://lore.kernel.org/r/20220309155716.3988480-1-maz@kernel.org/
Reported-by: Marc Zyngier 
Acked-by: James Morse 
Signed-off-by: Nathan Chancellor 
Link: https://lore.kernel.org/r/20220309191633.2307110-1-nathan@kernel.org
Signed-off-by: Catalin Marinas

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2022-03-09T20:59:21+00:00

Pull arm64 fixes from Catalin Marinas:

 - Fix compilation of eBPF object files that indirectly include
   mte-kasan.h.

 - Fix test for execute-only permissions with EPAN (Enhanced Privileged
   Access Never, ARMv8.7 feature).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: kasan: fix include error in MTE functions
  arm64: Ensure execute-only permissions are not allowed without EPAN

arm64: kasan: fix include error in MTE functions

2022-03-09T15:27:21+00:00

Fix `error: expected string literal in 'asm'`.
This happens when compiling an ebpf object file that includes
`net/net_namespace.h` from linux kernel headers.

Include trace:
     include/net/net_namespace.h:10
     include/linux/workqueue.h:9
     include/linux/timer.h:8
     include/linux/debugobjects.h:6
     include/linux/spinlock.h:90
     include/linux/workqueue.h:9
     arch/arm64/include/asm/spinlock.h:9
     arch/arm64/include/generated/asm/qrwlock.h:1
     include/asm-generic/qrwlock.h:14
     arch/arm64/include/asm/processor.h:33
     arch/arm64/include/asm/kasan.h:9
     arch/arm64/include/asm/mte-kasan.h:45
     arch/arm64/include/asm/mte-def.h:14

Signed-off-by: Paul Semel 
Fixes: 2cb34276427a ("arm64: kasan: simplify and inline MTE functions")
Cc:  # 5.12.x
Link: https://lore.kernel.org/r/bacb5387-2992-97e4-0c48-1ed925905bee@gmail.com
Signed-off-by: Catalin Marinas

Merge tag 'arm64-spectre-bhb-for-v5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2022-03-08T17:27:25+00:00

Pull arm64 spectre fixes from James Morse:
 "ARM64 Spectre-BHB mitigations:

   - Make EL1 vectors per-cpu

   - Add mitigation sequences to the EL1 and EL2 vectors on vulnerble
     CPUs

   - Implement ARCH_WORKAROUND_3 for KVM guests

   - Report Vulnerable when unprivileged eBPF is enabled"

* tag 'arm64-spectre-bhb-for-v5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  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
  arm64: entry.S: Add ventry overflow sanity checks

arm64: Ensure execute-only permissions are not allowed without EPAN

2022-03-08T10:03:51+00:00

Commit 18107f8a2df6 ("arm64: Support execute-only permissions with
Enhanced PAN") re-introduced execute-only permissions when EPAN is
available. When EPAN is not available, arch_filter_pgprot() is supposed
to change a PAGE_EXECONLY permission into PAGE_READONLY_EXEC. However,
if BTI or MTE are present, such check does not detect the execute-only
pgprot in the presence of PTE_GP (BTI) or MT_NORMAL_TAGGED (MTE),
allowing the user to request PROT_EXEC with PROT_BTI or PROT_MTE.

Remove the arch_filter_pgprot() function, change the default VM_EXEC
permissions to PAGE_READONLY_EXEC and update the protection_map[] array
at core_initcall() if EPAN is detected.

Signed-off-by: Catalin Marinas 
Fixes: 18107f8a2df6 ("arm64: Support execute-only permissions with Enhanced PAN")
Cc:  # 5.13.x
Acked-by: Will Deacon 
Reviewed-by: Vladimir Murzin 
Tested-by: Vladimir Murzin

arm64: Use the clearbhb instruction in mitigations

2022-02-24T14:02:44+00:00

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) 
Reviewed-by: Catalin Marinas 
Signed-off-by: James Morse

KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated

2022-02-24T13:58:52+00:00

KVM allows the guest to discover whether the ARCH_WORKAROUND SMCCC are
implemented, and to preserve that state during migration through its
firmware register interface.

Add the necessary boiler plate for SMCCC_ARCH_WORKAROUND_3.

Reviewed-by: Russell King (Oracle) 
Reviewed-by: Catalin Marinas 
Signed-off-by: James Morse

arm64: Mitigate spectre style branch history side channels

2022-02-24T13:58:52+00:00

Speculation attacks against some high-performance processors can
make use of branch history to influence future speculation.
When taking an exception from user-space, a sequence of branches
or a firmware call overwrites or invalidates the branch history.

The sequence of branches is added to the vectors, and should appear
before the first indirect branch. For systems using KPTI the sequence
is added to the kpti trampoline where it has a free register as the exit
from the trampoline is via a 'ret'. For systems not using KPTI, the same
register tricks are used to free up a register in the vectors.

For the firmware call, arch-workaround-3 clobbers 4 registers, so
there is no choice but to save them to the EL1 stack. This only happens
for entry from EL0, so if we take an exception due to the stack access,
it will not become re-entrant.

For KVM, the existing branch-predictor-hardening vectors are used.
When a spectre version of these vectors is in use, the firmware call
is sufficient to mitigate against Spectre-BHB. For the non-spectre
versions, the sequence of branches is added to the indirect vector.

Reviewed-by: Catalin Marinas 
Signed-off-by: James Morse