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 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 (3): arm: fiq: Replace default FIQ handler arm64: Introduce dummy version of asm/fiq.h irqchip: gic: Add support for IPI FIQ
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 | 137 ++++++++++++++++++++++++++++++--- arch/arm/kernel/setup.c | 8 +- arch/arm/kernel/smp.c | 64 ++++++++++++++++ arch/arm/kernel/traps.c | 32 +++++++- arch/arm64/include/asm/fiq.h | 18 +++++ drivers/irqchip/irq-gic.c | 165 +++++++++++++++++++++++++++++++++++++--- include/linux/irqchip/arm-gic.h | 3 + 9 files changed, 412 insertions(+), 23 deletions(-) create mode 100644 arch/arm64/include/asm/fiq.h
-- 1.9.3