Users of the recently proposed extensions to the FIQ infrastructure have reported a problem which causes the interrupt dispatcher in irq-gic.c (running as a normal IRQ handler) to try to acknowledge group 0 interrupts (group 0 should raise FIQ).
The problem occurs because the GICv1 found in Cortex A9 implementations explicitly uses the security state (normal or trusted world) to determine whether the interrupt controller should acknowledge group 0 interrupts. For FIQ to be useful as an NMI on Cortex A9 the kernel must run in in trusted world hence by default the GIC allows the CPU to acknowledge group 0 interrupts.
Two workarounds have been proposed, one which retrospectively corrects the problem if it is observed and one which uses the ARM MMU section flags to ensure the GIC driver can read INTACK from the current security context. The later workaround, which is both more invasive and higher performance[1], is presented in this patchset.
This patchset depends upon my own patchset for ARM providing additional FIQ infrastructure but does contain the changes to the GIC driver required to support FIQ. The effect of this is that workaround code is found primarily in patches 5, 6 and 7.
[1] http://thread.gmane.org/gmane.linux.ports.arm.kernel/331027/focus=1748892
Daniel Thompson (6): irqchip: gic: Provide support for interrupt grouping irqchip: gic: Add support for FIQ management irqchip: gic: Remove spin locks from eoi_irq arm: mm: Avoid ioremap_page_range() for non-secure mappings irqchip: gic: Use non-secure aliased register set when FIQ is enabled arm: imx: non-secure aliased mapping of GIC registers
Marek Vasut (3): ARM: dump the status of NS bit in L1 PTE ARM: Add L1 PTE non-secure mapping ARM: socfpga: Map the GIC CPU registers as MT_DEVICE_NS
arch/arm/include/asm/io.h | 5 +- arch/arm/include/asm/mach/map.h | 4 +- arch/arm/include/asm/pgtable-2level-hwdef.h | 1 + arch/arm/mach-imx/mach-imx6q.c | 11 ++ arch/arm/mach-socfpga/socfpga.c | 8 + arch/arm/mm/dump.c | 5 + arch/arm/mm/ioremap.c | 4 + arch/arm/mm/mmu.c | 13 +- drivers/irqchip/irq-gic.c | 240 ++++++++++++++++++++++++++-- include/linux/irqchip/arm-gic.h | 4 +- 10 files changed, 273 insertions(+), 22 deletions(-)
-- 1.9.3