This patchset makes it possible to use the kgdb NMI infrastructure on ARM platforms by providing a mutli-arch compatible means for drivers to manage FIQ routings.
First a quick summary of how the mainline kgdb NMI infrastructure (mostly found in drivers/tty/serial/kgdb_nmi.c) works. The kgdb infrastructure will re-route the kgdb console UART's interrupt signal from IRQ to FIQ. Naturally the UART will no longer function normally and will instead be managed by kgdb using the polled I/O functions. Any character delivered to the UART causes the kgdb handler function to be called.
Note that, within this patchset a serial driver explicitly consents (or not) to the abuse outlined by calling the appropriate registration during the .poll_init() callback.
The patch set is structured as follows:
The first six patches modify the interrupt system to make it easier to describe FIQ. The key concept is that a call to enable_fiq() must modify the IRQ/FIQ routing to that the FIQ really is enabled (rather than spuriously delivering the signal on the IRQ). To achieve this each interrupt controller registers two virqs for each hwirq (allowing IRQ and FIQ to be readily distinguished).
The next two patches (7 and 8) provide kgdb with a FIQ handler and a means for serial drivers to register their FIQ with kgdb.
Finally two example serial drivers are modified in order to register their FIQs with kgdb.
Major remaining TODO item is to modify the code to halt the other CPUs; at present this code sends IPIs (which use a normal IRQ) and busy waits for the other CPUs to halt. This means the benefits of invoking the debugger via NMI are not support realized on SMP systems. However I plan to tackle that later (i.e. when there's some consensus on whether this approach is the right way to handle FIQ).
Changes since v1:
* Fully fledged multi-arch support.
* Tested for correct FIQ operation on STiH416/B2020 (Cortex A9), qemu/versatile and qemu/vexpress-a15 (with self-written mods to the GIC model to support FIQ).
* Regression tested (and resulting bugs fixed) on qemu/versatile+DT and qemu/integreatorcp.
Anton Vorontsov (2): ARM: Move some macros from entry-armv to entry-header ARM: Add KGDB/KDB FIQ debugger generic code
Daniel Thompson (8): arm: fiq: Allow EOI to be communicated to the intc irqchip: gic: Provide support for interrupt grouping irqchip: gic: Introduce shadow irqs for FIQ ARM: vexpress: Extend UART with FIQ support ARM: STi: STiH41x: Extend UART with FIQ support. irqchip: vic: Introduce shadow irqs for FIQ serial: amba-pl011: Pass on FIQ information to KGDB. serial: asc: Add support for KGDB's FIQ/NMI mode
arch/arm/Kconfig | 2 + arch/arm/Kconfig.debug | 18 +++ arch/arm/boot/dts/stih415.dtsi | 4 +- arch/arm/boot/dts/stih416.dtsi | 4 +- arch/arm/boot/dts/vexpress-v2m-rs1.dtsi | 8 +- arch/arm/boot/dts/vexpress-v2p-ca15-tc1.dts | 10 +- arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 8 +- arch/arm/boot/dts/vexpress-v2p-ca5s.dts | 10 +- arch/arm/include/asm/fiq.h | 1 + arch/arm/include/asm/kgdb.h | 7 ++ arch/arm/kernel/Makefile | 1 + arch/arm/kernel/entry-armv.S | 151 +------------------------ arch/arm/kernel/entry-header.S | 164 ++++++++++++++++++++++++++++ arch/arm/kernel/fiq.c | 11 ++ arch/arm/kernel/kgdb_fiq.c | 117 ++++++++++++++++++++ arch/arm/kernel/kgdb_fiq_entry.S | 87 +++++++++++++++ arch/arm/mach-ep93xx/core.c | 6 +- arch/arm/mach-netx/generic.c | 3 +- arch/arm/mach-s3c64xx/common.c | 6 +- arch/arm/mach-versatile/core.c | 9 +- arch/arm/mach-versatile/include/mach/irqs.h | 76 ++++++------- arch/arm/plat-samsung/s5p-irq.c | 3 +- drivers/irqchip/irq-gic.c | 81 ++++++++++++-- drivers/irqchip/irq-vic.c | 87 ++++++++++++--- drivers/tty/serial/amba-pl011.c | 101 ++++++++++------- drivers/tty/serial/st-asc.c | 27 +++++ include/linux/irqchip/arm-gic.h | 3 + include/linux/irqchip/arm-vic.h | 8 +- 28 files changed, 733 insertions(+), 280 deletions(-) create mode 100644 arch/arm/kernel/kgdb_fiq.c create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S