GICV3中断控制器初始化调用链
/kernel/irq/handle.c:
#ifdef CONFIG_GENERIC_IRQ_MULTI_HANDLER
int __init set_handle_irq(void (*handle_irq)(struct pt_regs *))
{
if (handle_arch_irq)
return -EBUSY;
handle_arch_irq = handle_irq;
return 0;
}
#endif
/drivers/irqchip/irq-gic-v3.c:
static int __init gic_init_bases(void __iomem *dist_base,
struct redist_region *rdist_regs,
u32 nr_redist_regions,
u64 redist_stride,
struct fwnode_handle *handle)
{
... ...
set_handle_irq(gic_handle_irq);
... ...
}
/drivers/irqchip/irq-gic-v3.c:
IRQCHIP_DECLARE(gic_v3, "arm,gic-v3", gic_of_init);
static int __init gic_of_init(struct device_node *node, struct device_node *parent)
{
... ...
err = gic_init_bases(dist_base, rdist_regs, nr_redist_regions,
redist_stride, &node->fwnode);
... ....
}
/include/linux/irqchip.h:
#define IRQCHIP_DECLARE(name, compat, fn) OF_DECLARE_2(irqchip, name, compat, fn)
/include/linux/of.h:
#define OF_DECLARE_2(table, name, compat, fn) \
_OF_DECLARE(table, name, compat, fn, of_init_fn_2)
#define _OF_DECLARE(table, name, compat, fn, fn_type) \
static const struct of_device_id __of_table_##name \
__used __section(__##table##_of_table) \
= { .compatible = compat, \
.data = (fn == (fn_type)NULL) ? fn : fn }
/arch/arm64/kernel/vmlinux.lds:
.init.data : {
... ...
. = ALIGN(8); __irqchip_of_table = .; KEEP(*(__irqchip_of_table)) KEEP(*(__irqchip_of_table_end)) . = ALIGN(8);
... ...
}
/drivers/irqchip/irqchip.c:
void __init irqchip_init(void)
{
of_irq_init(__irqchip_of_table);
acpi_probe_device_table(irqchip);
}
/arch/arm64/kernel/irq.c:
void __init init_IRQ(void)
{
init_irq_stacks();
irqchip_init();
... ...
}
asmlinkage __visible void __init start_kernel(void)
{
... ...
init_IRQ();
... ...
}
中断的处理过程
异常向量表vectors
/arch/arm64/kernel/entry.S:
ENTRY(vectors)
kernel_ventry 1, sync_invalid // Synchronous EL1t
kernel_ventry 1, irq_invalid // IRQ EL1t
kernel_ventry 1, fiq_invalid // FIQ EL1t
kernel_ventry 1, error_invalid // Error EL1t
kernel_ventry 1, sync // Synchronous EL1h
kernel_ventry 1, irq // IRQ EL1h
kernel_ventry 1, fiq_invalid // FIQ EL1h
kernel_ventry 1, error // Error EL1h
kernel_ventry 0, sync // Synchronous 64-bit EL0
kernel_ventry 0, irq // IRQ 64-bit EL0
kernel_ventry 0, fiq_invalid // FIQ 64-bit EL0
kernel_ventry 0, error // Error 64-bit EL0
#ifdef CONFIG_COMPAT
kernel_ventry 0, sync_compat, 32 // Synchronous 32-bit EL0
kernel_ventry 0, irq_compat, 32 // IRQ 32-bit EL0
kernel_ventry 0, fiq_invalid_compat, 32 // FIQ 32-bit EL0
kernel_ventry 0, error_compat, 32 // Error 32-bit EL0
#else
kernel_ventry 0, sync_invalid, 32 // Synchronous 32-bit EL0
kernel_ventry 0, irq_invalid, 32 // IRQ 32-bit EL0
kernel_ventry 0, fiq_invalid, 32 // FIQ 32-bit EL0
kernel_ventry 0, error_invalid, 32 // Error 32-bit EL0
#endif
END(vectors)
el1_irq
/arch/arm64/kernel/entry.S:
.align 6
el1_irq:
kernel_entry 1
gic_prio_irq_setup pmr=x20, tmp=x1
enable_da_f
#ifdef CONFIG_ARM64_PSEUDO_NMI
test_irqs_unmasked res=x0, pmr=x20
cbz x0, 1f
bl asm_nmi_enter
1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
irq_handler
#ifdef CONFIG_PREEMPT
ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
/*
* DA_F were cleared at start of handling. If anything is set in DAIF,
* we come back from an NMI, so skip preemption
*/
mrs x0, daif
orr x24, x24, x0
alternative_else_nop_endif
cbnz x24, 1f // preempt count != 0 || NMI return path
bl arm64_preempt_schedule_irq // irq en/disable is done inside
1:
#endif
#ifdef CONFIG_ARM64_PSEUDO_NMI
/*
* When using IRQ priority masking, we can get spurious interrupts while
* PMR is set to GIC_PRIO_IRQOFF. An NMI might also have occurred in a
* section with interrupts disabled. Skip tracing in those cases.
*/
test_irqs_unmasked res=x0, pmr=x20
cbz x0, 1f
bl asm_nmi_exit
1:
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
#ifdef CONFIG_ARM64_PSEUDO_NMI
test_irqs_unmasked res=x0, pmr=x20
cbnz x0, 1f
#endif
bl trace_hardirqs_on
1:
#endif
kernel_exit 1
ENDPROC(el1_irq)
el0_irq
.align 6
el0_irq:
kernel_entry 0
el0_irq_naked:
gic_prio_irq_setup pmr=x20, tmp=x0
ct_user_exit_irqoff
enable_da_f
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_off
#endif
#ifdef CONFIG_HARDEN_BRANCH_PREDICTOR
tbz x22, #55, 1f
bl do_el0_irq_bp_hardening
1:
#endif
irq_handler
#ifdef CONFIG_TRACE_IRQFLAGS
bl trace_hardirqs_on
#endif
b ret_to_user
ENDPROC(el0_irq)
irq_handler
/arch/arm64/kernel/entry.S:
/*
* Interrupt handling.
*/
.macro irq_handler
ldr_l x1, handle_arch_irq
mov x0, sp
irq_stack_entry
blr x1
irq_stack_exit
.endm
gic_handle_irq
/drivers/irqchip/irq-gic-v3.c:
static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
{
u32 irqnr;
irqnr = gic_read_iar();
... ...
/* Check for special IDs first */
if ((irqnr >= 1020 && irqnr <= 1023))
return;
/* Treat anything but SGIs in a uniform way */
if (likely(irqnr > 15)) {
... ...
err = handle_domain_irq(gic_data.domain, irqnr, regs);
... ...
}
if (irqnr < 16) {
gic_write_eoir(irqnr);
if (static_branch_likely(&supports_deactivate_key))
gic_write_dir(irqnr);
#ifdef CONFIG_SMP
/*
* Unlike GICv2, we don't need an smp_rmb() here.
* The control dependency from gic_read_iar to
* the ISB in gic_write_eoir is enough to ensure
* that any shared data read by handle_IPI will
* be read after the ACK.
*/
handle_IPI(irqnr, regs);
#else
WARN_ONCE(true, "Unexpected SGI received!\n");
#endif
}
}
中断状态
- 硬件触发中断信号，中断assert，GIC标记中断为PENDING状态。
- GIC中distributor选择优先级最高的PENDING中断，发送给CPU interface, CPU interface对优先级进行判定，然后GIC发送中断请求信号给CPU, CPU进入中断异常后，通过GICC_IAR读取硬中断号，中断进入ACTIVE状态。
- 硬件触发新的中断信号，中断assert, GIC标记中断为ACTIVE_AND_PENDING状态
- CPU完成中断处理，发送EIO信号到GIC(写EOIR寄存器)
需要注意的是，INACTIVE PENDING ACTIVE ACTIVE_AND_PENDING，在此例中均属于GIC硬件所标记的中断状态，另外当GIC中断信号处于PENDING状态时，硬件外设无法发送新的中断信号给GIC中断控制器。事实上中断属异步通知并且没有排队的概念。