arm64: reduce stack use in irq_handler

[cascardo/linux.git] / arch / arm64 / include / asm / irq.h

diff --git a/arch/arm64/include/asm/irq.h b/arch/arm64/include/asm/irq.h
index 23eb450..3bece43 100644 (file)
--- a/arch/arm64/include/asm/irq.h
+++ b/arch/arm64/include/asm/irq.h
@@ -1,10 +1,62 @@
 #ifndef __ASM_IRQ_H
 #define __ASM_IRQ_H
 
+#define IRQ_STACK_SIZE                 THREAD_SIZE
+#define IRQ_STACK_START_SP             THREAD_START_SP
+
+#ifndef __ASSEMBLER__
+
+#include <linux/percpu.h>
+
 #include <asm-generic/irq.h>
+#include <asm/thread_info.h>
+
+#define __ARCH_HAS_DO_SOFTIRQ
 
 struct pt_regs;
 
+DECLARE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack);
+
+/*
+ * The highest address on the stack, and the first to be used. Used to
+ * find the dummy-stack frame put down by el?_irq() in entry.S, which
+ * is structured as follows:
+ *
+ *       ------------
+ *       |          |  <- irq_stack_ptr
+ *   top ------------
+ *       |   x19    | <- irq_stack_ptr - 0x08
+ *       ------------
+ *       |   x29    | <- irq_stack_ptr - 0x10
+ *       ------------
+ *
+ * where x19 holds a copy of the task stack pointer where the struct pt_regs
+ * from kernel_entry can be found.
+ *
+ */
+#define IRQ_STACK_PTR(cpu) ((unsigned long)per_cpu(irq_stack, cpu) + IRQ_STACK_START_SP)
+
+/*
+ * The offset from irq_stack_ptr where entry.S will store the original
+ * stack pointer. Used by unwind_frame() and dump_backtrace().
+ */
+#define IRQ_STACK_TO_TASK_STACK(ptr) (*((unsigned long *)((ptr) - 0x08)))
+
 extern void set_handle_irq(void (*handle_irq)(struct pt_regs *));
 
+static inline int nr_legacy_irqs(void)
+{
+       return 0;
+}
+
+static inline bool on_irq_stack(unsigned long sp, int cpu)
+{
+       /* variable names the same as kernel/stacktrace.c */
+       unsigned long low = (unsigned long)per_cpu(irq_stack, cpu);
+       unsigned long high = low + IRQ_STACK_START_SP;
+
+       return (low <= sp && sp <= high);
+}
+
+#endif /* !__ASSEMBLER__ */
 #endif