/*
* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
*
* This file contains the lowest level x86-specific interrupt
* entry, irq-stacks and irq statistics code. All the remaining
* irq logic is done by the generic kernel/irq/ code and
* by the x86-specific irq controller code. (e.g. i8259.c and
* io_apic.c.)
*/
/*
内核版本号:2.6.25.4
*/
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <asm/apic.h>
#include <asm/uaccess.h>
DEFINE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat);
EXPORT_PER_CPU_SYMBOL(irq_stat);
DEFINE_PER_CPU(struct pt_regs *, irq_regs);
EXPORT_PER_CPU_SYMBOL(irq_regs);
/*
* 'what should we do if we get a hw irq event on an illegal vector'.
* each architecture has to answer this themselves.
*/
void ack_bad_irq(unsigned int irq) //错误处理
{
printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
//APIC附加功能
#ifdef CONFIG_X86_LOCAL_APIC
/*
* Currently unexpected vectors happen only on SMP and APIC.
* We _must_ ack these because every local APIC has only N
* irq slots per priority level, and a 'hanging, unacked' IRQ
* holds up an irq slot - in excessive cases (when multiple
* unexpected vectors occur) that might lock up the APIC
* completely.
* But only ack when the APIC is enabled -AK
*/
if (cpu_has_apic) //在编译条件判断后进行硬件的检测，防错
ack_APIC_irq();
#endif
}
#ifdef CONFIG_4KSTACKS
/*
* per-CPU IRQ handling contexts (thread information and stack)
*/
union irq_ctx { //为CONFIG_4KSTACKS定义
struct thread_info tinfo;
u32 stack[THREAD_SIZE/sizeof(u32)];
};
//实例化软中断和硬件中断
static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
#endif
/*
* do_IRQ handles all normal device IRQ's (the special
* SMP cross-CPU interrupts have their own specific
* handlers).
*/
unsigned int do_IRQ(struct pt_regs *regs) //中断,不包括SMP处理的
{
struct pt_regs *old_regs;
/* high bit used in ret_from_ code */
int irq = ~regs->orig_ax;
struct irq_desc *desc = irq_desc + irq;
#ifdef CONFIG_4KSTACKS
union irq_ctx *curctx, *irqctx;
u32 *isp;
#endif
if (unlikely((unsigned)irq >= NR_IRQS)) { //错误处理
printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
__FUNCTION__, irq);
BUG();
}
old_regs = set_irq_regs(regs); //记录当前中断寄存器
irq_enter(); //进入中断
#ifdef CONFIG_DEBUG_STACKOVERFLOW
/* Debugging check for stack overflow: is there less than 1KB free? */
//对栈溢出的处理
{
long sp;
__asm__ __volatile__("andl %%esp,%0" :
"=r" (sp) : "0" (THREAD_SIZE - 1)); //对sp进行处理
if (unlikely(sp < (sizeof(struct thread_info) + STACK_WARN))) { //判断是否溢出,并进行处理
printk("do_IRQ: stack overflow: %ld\n",
sp - sizeof(struct thread_info)); //输出溢出线程的信息代号
dump_stack(); //中断清除
}
}
#endif
#ifdef CONFIG_4KSTACKS
curctx = (union irq_ctx *) current_thread_info(); //将当前线程的信息赋值给curctx
irqctx = hardirq_ctx[smp_processor_id()]; //切换到中断栈
/*
* this is where we switch to the IRQ stack. However, if we are
* already using the IRQ stack (because we interrupted a hardirq
* handler) we can't do that and just have to keep using the
* current stack (which is the irq stack already after all)
*/
//通常curctx == irqctx.除非中断程序使用独立的4K堆栈.
if (curctx != irqctx) {
int arg1, arg2, bx;
/* build the stack frame on the IRQ stack */
//为curctx != irqctx的情况建立中断栈
isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
irqctx->tinfo.task = curctx->tinfo.task;
irqctx->tinfo.previous_esp = current_stack_pointer;
/*
* Copy the softirq bits in preempt_count so that the
* softirq checks work in the hardirq context.
*/
irqctx->tinfo.preempt_count =
(irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
(curctx->tinfo.preempt_count & SOFTIRQ_MASK);
asm volatile(
" xchgl %%ebx,%%esp \n"
" call *%%edi \n"
" movl %%ebx,%%esp \n"
: "=a" (arg1), "=d" (arg2), "=b" (bx)
: "0" (irq), "1" (desc), "2" (isp),
"D" (desc->handle_irq)
: "memory", "cc"
);
} else
#endif
desc->handle_irq(irq, desc); //struct irq_desc *desc = irq_desc + irq;
irq_exit(); //退出中断
set_irq_regs(old_regs);//还原中断寄存器
return 1;
}
#ifdef CONFIG_4KSTACKS
static char softirq_stack[NR_CPUS * THREAD_SIZE]
__attribute__((__section__(".bss.page_aligned")));
static char hardirq_stack[NR_CPUS * THREAD_SIZE]
__attribute__((__section__(".bss.page_aligned")));
/*
* allocate per-cpu stacks for hardirq and for softirq processing
*/
void irq_ctx_init(int cpu) //对4k中断栈的初始化
{
union irq_ctx *irqctx;
if (hardirq_ctx[cpu])
return;
irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
hardirq_ctx[cpu] = irqctx;
irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
irqctx->tinfo.task = NULL;
irqctx->tinfo.exec_domain = NULL;
irqctx->tinfo.cpu = cpu;
irqctx->tinfo.preempt_count = 0;
irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
softirq_ctx[cpu] = irqctx;
printk("CPU %u irqstacks, hard=%p soft=%p\n",
cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
}
void irq_ctx_exit(int cpu) //设置当前CPU的硬件中断为空
{
hardirq_ctx[cpu] = NULL;
}
extern asmlinkage void __do_softirq(void);
asmlinkage void do_softirq(void) //软件中断处理
{
unsigned long flags;
struct thread_info *curctx;
union irq_ctx *irqctx;
u32 *isp;
if (in_interrupt()) //假如当前存在中断,退出
return;
local_irq_save(flags); //屏蔽中断,并将中断状态保存在flags中
//检测到有 pending 的软中断需要处理的时候，则会显示的调用 do_softirq() 来处理软中断
if (local_softirq_pending()) {
curctx = current_thread_info();
irqctx = softirq_ctx[smp_processor_id()];
irqctx->tinfo.task = curctx->task;
irqctx->tinfo.previous_esp = current_stack_pointer;
/* build the stack frame on the softirq stack */
isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
asm volatile(
" xchgl %%ebx,%%esp \n"
" call __do_softirq \n"
" movl %%ebx,%%esp \n"
: "=b"(isp)
: "0"(isp)
: "memory", "cc", "edx", "ecx", "eax"
);
/*
* Shouldnt happen, we returned above if in_interrupt():
*/
WARN_ON_ONCE(softirq_count());
}
local_irq_restore(flags); //取消中断的屏蔽
}
#endif
/*
* Interrupt statistics:
*/
atomic_t irq_err_count; //定义原子量
/*
* /proc/interrupts printing:
*/
int show_interrupts(struct seq_file *p, void *v)
{
int i = *(loff_t *) v, j;
struct irqaction * action;
unsigned long flags;
if (i == 0) { //当i为0时，输出相关信息
seq_printf(p, " ");
for_each_online_cpu(j)
seq_printf(p, "CPU%-8d",j);
seq_putc(p, '\n');
}
if (i < NR_IRQS) { //当i小于NR_IRQS时
unsigned any_count = 0;
spin_lock_irqsave(&irq_desc[i].lock, flags); //屏蔽自旋锁中断
#ifndef CONFIG_SMP //针对any_count的值增加SMP的处理
any_count = kstat_irqs(i);
#else
for_each_online_cpu(j)
any_count |= kstat_cpu(j).irqs[i];
#endif
action = irq_desc[i].action;
if (!action && !any_count) //当前irq_desc.action != any_count时,跳过
goto skip;
seq_printf(p, "%3d: ",i);
#ifndef CONFIG_SMP
seq_printf(p, "%10u ", kstat_irqs(i));
#else
for_each_online_cpu(j)
seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
seq_printf(p, " %8s", irq_desc[i].chip->name);
seq_printf(p, "-%-8s", irq_desc[i].name);
if (action) {
seq_printf(p, " %s", action->name);
while ((action = action->next) != NULL) //遍历action
seq_printf(p, ", %s", action->name);
}
seq_putc(p, '\n');
skip: //当irq_desc.action != any_count,直接解除屏蔽
spin_unlock_irqrestore(&irq_desc[i].lock, flags);
} else if (i == NR_IRQS) {
seq_printf(p, "NMI: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ", nmi_count(j));
seq_printf(p, " Non-maskable interrupts\n");
#ifdef CONFIG_X86_LOCAL_APIC
seq_printf(p, "LOC: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).apic_timer_irqs);
seq_printf(p, " Local timer interrupts\n");
#endif
#ifdef CONFIG_SMP
seq_printf(p, "RES: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).irq_resched_count);
seq_printf(p, " Rescheduling interrupts\n");
seq_printf(p, "CAL: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).irq_call_count);
seq_printf(p, " function call interrupts\n");
seq_printf(p, "TLB: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).irq_tlb_count);
seq_printf(p, " TLB shootdowns\n");
#endif
seq_printf(p, "TRM: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).irq_thermal_count);
seq_printf(p, " Thermal event interrupts\n");
seq_printf(p, "SPU: ");
for_each_online_cpu(j)
seq_printf(p, "%10u ",
per_cpu(irq_stat,j).irq_spurious_count);
seq_printf(p, " Spurious interrupts\n");
seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
#if defined(CONFIG_X86_IO_APIC)
seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
#endif
}
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
#include <mach_apic.h>
void fixup_irqs(cpumask_t map)
{
unsigned int irq;
static int warned;
for (irq = 0; irq < NR_IRQS; irq++) {
cpumask_t mask;
if (irq == 2) //排除irq=2的情况
continue;
cpus_and(mask, irq_desc[irq].affinity, map);
if (any_online_cpu(mask) == NR_CPUS) {
printk("Breaking affinity for irq %i\n", irq);
mask = map;
}
if (irq_desc[irq].chip->set_affinity)
irq_desc[irq].chip->set_affinity(irq, mask);
else if (irq_desc[irq].action && !(warned++))
printk("Cannot set affinity for irq %i\n", irq);
}
#if 0
barrier();
/* Ingo Molnar says: "after the IO-APIC masks have been redirected
[note the nop - the interrupt-enable boundary on x86 is two
instructions from sti] - to flush out pending hardirqs and
IPIs. After this point nothing is supposed to reach this CPU." */
__asm__ __volatile__("sti; nop; cli");
barrier();
#else
/* That doesn't seem sufficient. Give it 1ms. */
local_irq_enable(); //允许中断
mdelay(1);
local_irq_disable(); //禁止中断
#endif
}
#endif
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