2 * linux/arch/i386/kernel/irq.c
4 * Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
6 * This file contains the lowest level x86-specific interrupt
7 * entry, irq-stacks and irq statistics code. All the remaining
8 * irq logic is done by the generic kernel/irq/ code and
9 * by the x86-specific irq controller code. (e.g. i8259.c and
13 #include <asm/uaccess.h>
14 #include <linux/module.h>
15 #include <linux/seq_file.h>
16 #include <linux/interrupt.h>
17 #include <linux/kernel_stat.h>
18 #include <linux/notifier.h>
19 #include <linux/cpu.h>
20 #include <linux/delay.h>
24 DEFINE_PER_CPU(irq_cpustat_t, irq_stat) ____cacheline_internodealigned_in_smp;
25 EXPORT_PER_CPU_SYMBOL(irq_stat);
27 #ifndef CONFIG_X86_LOCAL_APIC
29 * 'what should we do if we get a hw irq event on an illegal vector'.
30 * each architecture has to answer this themselves.
32 void ack_bad_irq(unsigned int irq)
34 printk("unexpected IRQ trap at vector %02x\n", irq);
38 #ifdef CONFIG_4KSTACKS
40 * per-CPU IRQ handling contexts (thread information and stack)
43 struct thread_info tinfo;
44 u32 stack[THREAD_SIZE/sizeof(u32)];
47 static union irq_ctx *hardirq_ctx[NR_CPUS] __read_mostly;
48 static union irq_ctx *softirq_ctx[NR_CPUS] __read_mostly;
52 * do_IRQ handles all normal device IRQ's (the special
53 * SMP cross-CPU interrupts have their own specific
56 fastcall unsigned int do_IRQ(struct pt_regs *regs)
58 struct pt_regs *old_regs;
59 /* high bit used in ret_from_ code */
60 int irq = ~regs->orig_eax;
61 struct irq_desc *desc = irq_desc + irq;
62 #ifdef CONFIG_4KSTACKS
63 union irq_ctx *curctx, *irqctx;
68 if (unlikely((unsigned)irq >= NR_IRQS)) {
69 printk(KERN_EMERG "%s: cannot handle IRQ %d\n",
74 old_regs = set_irq_regs(regs);
76 #ifdef CONFIG_DEBUG_STACKOVERFLOW
77 /* Debugging check for stack overflow: is there less than 1KB free? */
81 __asm__ __volatile__("andl %%esp,%0" :
82 "=r" (esp) : "0" (THREAD_SIZE - 1));
83 if (unlikely(esp < (sizeof(struct thread_info) + STACK_WARN))) {
84 printk("do_IRQ: stack overflow: %ld\n",
85 esp - sizeof(struct thread_info));
91 #ifdef CONFIG_4KSTACKS
93 curctx = (union irq_ctx *) current_thread_info();
94 irqctx = hardirq_ctx[smp_processor_id()];
97 * this is where we switch to the IRQ stack. However, if we are
98 * already using the IRQ stack (because we interrupted a hardirq
99 * handler) we can't do that and just have to keep using the
100 * current stack (which is the irq stack already after all)
102 if (curctx != irqctx) {
105 /* build the stack frame on the IRQ stack */
106 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
107 irqctx->tinfo.task = curctx->tinfo.task;
108 irqctx->tinfo.previous_esp = current_stack_pointer;
111 * Copy the softirq bits in preempt_count so that the
112 * softirq checks work in the hardirq context.
114 irqctx->tinfo.preempt_count =
115 (irqctx->tinfo.preempt_count & ~SOFTIRQ_MASK) |
116 (curctx->tinfo.preempt_count & SOFTIRQ_MASK);
119 " xchgl %%ebx,%%esp \n"
121 " movl %%ebx,%%esp \n"
122 : "=a" (arg1), "=d" (arg2), "=b" (ebx)
123 : "0" (irq), "1" (desc), "2" (isp),
124 "D" (desc->handle_irq)
129 desc->handle_irq(irq, desc);
132 set_irq_regs(old_regs);
136 #ifdef CONFIG_4KSTACKS
139 * These should really be __section__(".bss.page_aligned") as well, but
140 * gcc's 3.0 and earlier don't handle that correctly.
142 static char softirq_stack[NR_CPUS * THREAD_SIZE]
143 __attribute__((__aligned__(THREAD_SIZE)));
145 static char hardirq_stack[NR_CPUS * THREAD_SIZE]
146 __attribute__((__aligned__(THREAD_SIZE)));
149 * allocate per-cpu stacks for hardirq and for softirq processing
151 void irq_ctx_init(int cpu)
153 union irq_ctx *irqctx;
155 if (hardirq_ctx[cpu])
158 irqctx = (union irq_ctx*) &hardirq_stack[cpu*THREAD_SIZE];
159 irqctx->tinfo.task = NULL;
160 irqctx->tinfo.exec_domain = NULL;
161 irqctx->tinfo.cpu = cpu;
162 irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
163 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
165 hardirq_ctx[cpu] = irqctx;
167 irqctx = (union irq_ctx*) &softirq_stack[cpu*THREAD_SIZE];
168 irqctx->tinfo.task = NULL;
169 irqctx->tinfo.exec_domain = NULL;
170 irqctx->tinfo.cpu = cpu;
171 irqctx->tinfo.preempt_count = 0;
172 irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
174 softirq_ctx[cpu] = irqctx;
176 printk("CPU %u irqstacks, hard=%p soft=%p\n",
177 cpu,hardirq_ctx[cpu],softirq_ctx[cpu]);
180 void irq_ctx_exit(int cpu)
182 hardirq_ctx[cpu] = NULL;
185 extern asmlinkage void __do_softirq(void);
187 asmlinkage void do_softirq(void)
190 struct thread_info *curctx;
191 union irq_ctx *irqctx;
197 local_irq_save(flags);
199 if (local_softirq_pending()) {
200 curctx = current_thread_info();
201 irqctx = softirq_ctx[smp_processor_id()];
202 irqctx->tinfo.task = curctx->task;
203 irqctx->tinfo.previous_esp = current_stack_pointer;
205 /* build the stack frame on the softirq stack */
206 isp = (u32*) ((char*)irqctx + sizeof(*irqctx));
209 " xchgl %%ebx,%%esp \n"
210 " call __do_softirq \n"
211 " movl %%ebx,%%esp \n"
214 : "memory", "cc", "edx", "ecx", "eax"
217 * Shouldnt happen, we returned above if in_interrupt():
219 WARN_ON_ONCE(softirq_count());
222 local_irq_restore(flags);
225 EXPORT_SYMBOL(do_softirq);
229 * Interrupt statistics:
232 atomic_t irq_err_count;
235 * /proc/interrupts printing:
238 int show_interrupts(struct seq_file *p, void *v)
240 int i = *(loff_t *) v, j;
241 struct irqaction * action;
246 for_each_online_cpu(j)
247 seq_printf(p, "CPU%-8d",j);
252 spin_lock_irqsave(&irq_desc[i].lock, flags);
253 action = irq_desc[i].action;
256 seq_printf(p, "%3d: ",i);
258 seq_printf(p, "%10u ", kstat_irqs(i));
260 for_each_online_cpu(j)
261 seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
263 seq_printf(p, " %8s", irq_desc[i].chip->name);
264 seq_printf(p, "-%-8s", irq_desc[i].name);
265 seq_printf(p, " %s", action->name);
267 for (action=action->next; action; action = action->next)
268 seq_printf(p, ", %s", action->name);
272 spin_unlock_irqrestore(&irq_desc[i].lock, flags);
273 } else if (i == NR_IRQS) {
274 seq_printf(p, "NMI: ");
275 for_each_online_cpu(j)
276 seq_printf(p, "%10u ", nmi_count(j));
278 #ifdef CONFIG_X86_LOCAL_APIC
279 seq_printf(p, "LOC: ");
280 for_each_online_cpu(j)
281 seq_printf(p, "%10u ",
282 per_cpu(irq_stat,j).apic_timer_irqs);
285 seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
286 #if defined(CONFIG_X86_IO_APIC)
287 seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
293 #ifdef CONFIG_HOTPLUG_CPU
294 #include <mach_apic.h>
296 void fixup_irqs(cpumask_t map)
301 for (irq = 0; irq < NR_IRQS; irq++) {
306 cpus_and(mask, irq_desc[irq].affinity, map);
307 if (any_online_cpu(mask) == NR_CPUS) {
308 printk("Breaking affinity for irq %i\n", irq);
311 if (irq_desc[irq].chip->set_affinity)
312 irq_desc[irq].chip->set_affinity(irq, mask);
313 else if (irq_desc[irq].action && !(warned++))
314 printk("Cannot set affinity for irq %i\n", irq);
319 /* Ingo Molnar says: "after the IO-APIC masks have been redirected
320 [note the nop - the interrupt-enable boundary on x86 is two
321 instructions from sti] - to flush out pending hardirqs and
322 IPIs. After this point nothing is supposed to reach this CPU." */
323 __asm__ __volatile__("sti; nop; cli");
326 /* That doesn't seem sufficient. Give it 1ms. */