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    Subject[PATCH v4 0/6] arm: Implement arch_trigger_all_cpu_backtrace
    Date
    This patchset implements arch_trigger_all_cpu_backtrace for arm.

    Non-maskable signalling relies on the kernel being able to access FIQ
    and therefore, for devices that implement TrustZone, it will work only on
    systems that boot the kernel in secure mode.

    Tested on Freescale iMX.6 (both via SysRq-l and by deliberately locking
    up the kernel with CONFIG_DEBUG_SPINLOCK=y).

    Changes since v3:

    * Replaced push/pop with stmfd/ldmfd respectively (review of Nicolas
    Pitre).

    * Really fix bad pt_regs pointer generation in __fiq_abt.

    * Remove fiq_safe_migration_lock and associated logic in
    gic_raise_softirq() (review of Russell King)

    * Restructured to introduce the default FIQ handler first, before the
    new features (review of Russell King).

    Changes since v2:

    * Removed redundant header guards from arch/arm64/include/asm/fiq.h
    (review of Catalin Marinas).

    * Moved svc_exit_via_fiq macro to entry-header.S (review of Nicolas
    Pitre).

    Changes since v1:

    * Restructured to sit nicely on a similar FYI patchset from Russell
    King. It now effectively replaces the work in progress final patch
    with something much more complete.

    * Implemented (and tested) a Thumb-2 implementation of svc_exit_via_fiq
    (review of Nicolas Pitre)

    * Dropped the GIC group 0 workaround patch. The issue of FIQ interrupts
    being acknowledged by the IRQ handler does still exist but should be
    harmless because the IRQ handler will still wind up calling
    ipi_cpu_backtrace().

    * Removed any dependency on CONFIG_FIQ; all cpu backtrace effectively
    becomes a platform feature (although the use of non-maskable
    interrupts to implement it is best effort rather than guaranteed).

    * Better comments highlighting usage of RAZ/WI registers (and parts of
    registers) in the GIC code.

    Changes *before* v1:

    * This patchset is a hugely cut-down successor to "[PATCH v11 00/19]
    arm: KGDB NMI/FIQ support". Thanks to Thomas Gleixner for suggesting
    the new structure. For historic details see:
    https://lkml.org/lkml/2014/9/2/227

    * Fix bug in __fiq_abt (no longer passes a bad struct pt_regs value).
    In fixing this we also remove the useless indirection previously
    found in the fiq_handler macro.

    * Make default fiq handler "always on" by migrating from fiq.c to
    traps.c and replace do_unexp_fiq with the new handler (review
    of Russell King).

    * Add arm64 version of fiq.h (review of Russell King)

    * Removed conditional branching and code from irq-gic.c, this is
    replaced by much simpler code that relies on the GIC specification's
    heavy use of read-as-zero/write-ignored (review of Russell King)


    Daniel Thompson (4):
    arm: fiq: Replace default FIQ handler
    arm64: Introduce dummy version of asm/fiq.h
    irqchip: gic: Add support for IPI FIQ
    arm: smp: Handle ipi_cpu_backtrace() using FIQ (if available)

    Russell King (2):
    ARM: remove unused do_unexp_fiq() function
    ARM: add basic support for on-demand backtrace of other CPUs

    arch/arm/include/asm/irq.h | 5 ++
    arch/arm/include/asm/smp.h | 3 +
    arch/arm/kernel/entry-armv.S | 95 ++++++++++++++++++++++++---
    arch/arm/kernel/entry-header.S | 47 ++++++++++++++
    arch/arm/kernel/setup.c | 8 ++-
    arch/arm/kernel/smp.c | 65 +++++++++++++++++++
    arch/arm/kernel/traps.c | 32 ++++++++-
    arch/arm64/include/asm/fiq.h | 8 +++
    drivers/irqchip/irq-gic.c | 140 ++++++++++++++++++++++++++++++++++++++--
    include/linux/irqchip/arm-gic.h | 3 +
    10 files changed, 387 insertions(+), 19 deletions(-)
    create mode 100644 arch/arm64/include/asm/fiq.h

    --
    1.9.3



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