lkml.org 
[lkml]   [2018]   [Feb]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.14 036/195] [Variant 3/Meltdown] arm64: erratum: Work around Falkor erratum #E1003 in trampoline code
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Will Deacon <will.deacon@arm.com>


    Commit d1777e686ad1 upstream.

    We rely on an atomic swizzling of TTBR1 when transitioning from the entry
    trampoline to the kernel proper on an exception. We can't rely on this
    atomicity in the face of Falkor erratum #E1003, so on affected cores we
    can issue a TLB invalidation to invalidate the walk cache prior to
    jumping into the kernel. There is still the possibility of a TLB conflict
    here due to conflicting walk cache entries prior to the invalidation, but
    this doesn't appear to be the case on these CPUs in practice.

    Reviewed-by: Mark Rutland <mark.rutland@arm.com>
    Tested-by: Laura Abbott <labbott@redhat.com>
    Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/arm64/Kconfig | 17 +++++------------
    arch/arm64/kernel/entry.S | 12 ++++++++++++
    2 files changed, 17 insertions(+), 12 deletions(-)

    --- a/arch/arm64/Kconfig
    +++ b/arch/arm64/Kconfig
    @@ -504,20 +504,13 @@ config CAVIUM_ERRATUM_30115
    config QCOM_FALKOR_ERRATUM_1003
    bool "Falkor E1003: Incorrect translation due to ASID change"
    default y
    - select ARM64_PAN if ARM64_SW_TTBR0_PAN
    help
    On Falkor v1, an incorrect ASID may be cached in the TLB when ASID
    - and BADDR are changed together in TTBRx_EL1. The workaround for this
    - issue is to use a reserved ASID in cpu_do_switch_mm() before
    - switching to the new ASID. Saying Y here selects ARM64_PAN if
    - ARM64_SW_TTBR0_PAN is selected. This is done because implementing and
    - maintaining the E1003 workaround in the software PAN emulation code
    - would be an unnecessary complication. The affected Falkor v1 CPU
    - implements ARMv8.1 hardware PAN support and using hardware PAN
    - support versus software PAN emulation is mutually exclusive at
    - runtime.
    -
    - If unsure, say Y.
    + and BADDR are changed together in TTBRx_EL1. Since we keep the ASID
    + in TTBR1_EL1, this situation only occurs in the entry trampoline and
    + then only for entries in the walk cache, since the leaf translation
    + is unchanged. Work around the erratum by invalidating the walk cache
    + entries for the trampoline before entering the kernel proper.

    config QCOM_FALKOR_ERRATUM_1009
    bool "Falkor E1009: Prematurely complete a DSB after a TLBI"
    --- a/arch/arm64/kernel/entry.S
    +++ b/arch/arm64/kernel/entry.S
    @@ -941,6 +941,18 @@ __ni_sys_trace:
    sub \tmp, \tmp, #(SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE)
    bic \tmp, \tmp, #USER_ASID_FLAG
    msr ttbr1_el1, \tmp
    +#ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003
    +alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003
    + /* ASID already in \tmp[63:48] */
    + movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12)
    + movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12)
    + /* 2MB boundary containing the vectors, so we nobble the walk cache */
    + movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12)
    + isb
    + tlbi vae1, \tmp
    + dsb nsh
    +alternative_else_nop_endif
    +#endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */
    .endm

    .macro tramp_unmap_kernel, tmp

    \
     
     \ /
      Last update: 2018-02-15 18:50    [W:3.020 / U:0.516 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site