ARM64 el1_irq 处理

.align 6
el1_irq:
 kernel_entry 1
 msr daifclr, #1    //enable fiq
 enable_dbg_if_not_stepping x0
#ifdef CONFIG_TRACE_IRQFLAGS
 bl trace_hardirqs_off
#endif

#ifdef CONFIG_PREEMPT
 get_thread_info tsk
 ldr w24, [tsk, #TI_PREEMPT]  // get preempt count
 add w0, w24, #1   // increment it
 str w0, [tsk, #TI_PREEMPT]
#endif

 
irq_handler 
#ifdef CONFIG_PREEMPT
 str w24, [tsk, #TI_PREEMPT]  // restore preempt count
 cbnz w24, 1f    // preempt count != 0
 ldr x0, [tsk, #TI_FLAGS]  // get flags
 tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
 bl el1_preempt
1:
#endif
 
 
 
#ifdef CONFIG_TRACE_IRQFLAGS
 bl trace_hardirqs_on
#endif
 
 
 
 kernel_exit 1
ENDPROC(el1_irq)
 
 
 
/*
 * Interrupt handling.
 */
 .macro irq_handler
 ldr_l x1, handle_arch_irq

相关栈处理：

.macro irq_stack_entry
 mov x19, sp   // preserve the original sp
 /*
  * Compare sp with the current thread_info, if the top
  * ~(THREAD_SIZE - 1) bits match, we are on a task stack, and
  * should switch to the irq stack.
  */
 and x25, x19, #~(THREAD_SIZE - 1)
 cmp x25, tsk
 b.ne 9998f
 this_cpu_ptr irq_stack, x25, x26
 mov x26, #IRQ_STACK_START_SP
 add x26, x25, x26
 /* switch to the irq stack */
 mov sp, x26
 /*
  * Add a dummy stack frame, this non-standard format is fixed up
  * by unwind_frame()
  */
 stp     x29, x19, [sp, #-16]!
 mov x29, sp
9998:
 .endm
 
 
 
 
 
 /*
  * x19 should be preserved between irq_stack_entry and
  * irq_stack_exit.
  */
 .macro irq_stack_exit
 mov sp, x19
 .endm

初始化处理：

kernel/irq.c
 
void __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
{
 if (handle_arch_irq)
  return;
 handle_arch_irq = handle_irq;
}

需要注意的是，这里设置的handle_irq是主irq_chip下的处理函数，比如对于GIC来说，其设置是：gic_handle_irq。

static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
{
 u32 irqstat, irqnr;
 struct gic_chip_data *gic = &gic_data[0];
 void __iomem *cpu_base = gic_data_cpu_base(gic);
 do {
  irqstat = readl_relaxed(cpu_base + GIC_CPU_INTACK);
  irqnr = irqstat & GICC_IAR_INT_ID_MASK;//#define GICC_IAR_INT_ID_MASK  0x3ff

上面两个操作说明，中断号是中断处理程序去读状态寄存器后得到的。

if (likely(irqnr > 15 && irqnr < 1020)) {
   if (static_key_true(&supports_deactivate))
    writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI);
   handle_domain_irq(gic->domain, irqnr, regs);
   continue;
  }
(irqnr < 16) {
   writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI);
   if (static_key_true(&supports_deactivate))
    writel_relaxed(irqstat, cpu_base + GIC_CPU_DEACTIVATE);
#ifdef CONFIG_SMP
   /*
    * Ensure any shared data written by the CPU sending
    * the IPI is read after we've read the ACK register
    * on the GIC.
    *
    * Pairs with the write barrier in gic_raise_softirq
    */
   smp_rmb();
   handle_IPI(irqnr, regs);
#endif
   continue;
  }
  break;
 } while (1);

}